JP2011196243A - Engine control unit and fuel pump control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress such a state in which a fuel pump is controlled while using an abnormal pulse signal as it is with noise superposed or the like, in a fuel pump control system outputting a pulse signal representing the drive duty/drive frequency of the fuel pump from an engine control unit to a fuel pump control unit.SOLUTION: In this engine control unit, the drive duty is converted into an instructing duty within an intermediate area excluding at least 0% and 100%, and the drive frequency is converted into a lower instructing frequency and output toward the fuel pump control unit. In the fuel pump control unit, the duty of the pulse signal is converted into the command value of the drive duty, the frequency of the pulse signal is converted into the drive frequency, and drive output is determined based on these drive duty and drive frequency; meanwhile, the presence or absence of the abnormality of the pulse signal is diagnosed based on the duty and frequency of the pulse signal. When occurrence of the abnormality is diagnosed, the drive output is changed over to drive output for a fail.

Description

  The present invention relates to an engine control unit and a fuel pump control system. More specifically, the present invention relates to a fuel pump control system that outputs a signal indicating a drive duty of a fuel pump from the engine control unit to the fuel pump control unit, and the fuel The present invention relates to an engine control unit used in a pump control system.

  In Patent Document 1, a fuel control ECU and a fuel pump control device are individually provided. The fuel pump control device receives a low frequency duty signal from the fuel control ECU, converts it into a high frequency duty signal, and PWMs the fuel pump. A fuel pump control system adapted for control is disclosed.

JP-A-5-296113

By the way, when an analog pulse signal (square wave) instructing the drive duty is transmitted / received between control units, noise may be superimposed on the pulse signal. Conventionally, the fuel is generated by using the pulse signal on which noise is superimposed as it is. There are problems such as the pump being controlled, causing fluctuations in fuel pressure, and the responsiveness of fuel pressure control being reduced.
The present invention has been made in view of the above problems, and provides an engine control unit and a fuel pump control system capable of suppressing the control of the fuel pump using an abnormal pulse signal such as noise superimposed as it is. For the purpose.

  Therefore, the engine control unit according to the present invention is directed to a fuel pump control unit that controls a fuel injection valve of an engine and outputs a drive output for driving a fuel pump that pumps fuel to the fuel injection valve. An engine control unit that outputs a signal that indicates a driving duty of the fuel pump, calculates the driving duty, converts the driving duty into a duty in an intermediate region excluding at least 0% and 100%, and the conversion A pulse signal having a later duty is output to the fuel pump control unit as a signal indicating the drive duty.

  According to the above invention, since the duty of the pulse signal transmitted from the engine control unit to the fuel pump control unit is limited to the duty in the intermediate range, it is possible to easily distinguish the presence or absence of noise superimposition on the pulse signal in the fuel pump control unit, It can be suppressed that the fuel pump control unit controls the fuel pump using the duty of the abnormal pulse signal as it is.

1 is a system configuration diagram of an internal combustion engine in an embodiment. It is a flowchart which shows the pump control process by the side of ECM in embodiment. It is a diagram which shows the characteristic which converts the drive frequency by the side of ECM in embodiment into the cycle T2 for transmission. It is a diagram which shows the characteristic which converts the drive duty by the side of ECM in embodiment into the ON time T1 for transmission. It is a time chart which shows the output form of the instruction | indication pulse signal transmitted to EFP from ECM in embodiment. It is a flowchart which shows the pump control process by the side of the FPCM in embodiment. It is a diagram which shows the characteristic which converts ON time T1 for transmission by the FPCM side in embodiment into a drive duty. It is a diagram which shows the characteristic which converts the cycle T2 for transmission on the FPCM side in the embodiment into a drive cycle (drive frequency). It is a flowchart which shows the abnormality diagnosis process and fail safe process of the instruction | indication pulse signal by the FPCM side in embodiment.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of an internal combustion engine for a vehicle including an engine control unit and a fuel pump control system according to the present invention.
In FIG. 1, an internal combustion engine (engine) 1 includes a fuel injection valve 3 in an intake passage (intake port) 2 thereof, and fuel injection to the internal combustion engine 1 is performed by opening the fuel injection valve 3.

The fuel injected by the fuel injection valve 3 is sucked into the combustion chamber 5 together with air through the intake valve 4 and ignited and burned by spark ignition by the spark plug 6. The combustion gas in the combustion chamber 5 is discharged to the exhaust passage 8 through the exhaust valve 7.
An electronically controlled throttle 10 that is opened and closed by a throttle motor 9 is disposed upstream of the portion of the intake passage 2 where the fuel injection valve 3 is disposed, and the intake of the internal combustion engine 1 is determined by the opening of the electronically controlled throttle 10. Adjust the air volume.

In addition, a fuel supply device 13 that pressure-feeds the fuel in the fuel tank 11 to the fuel injection valve 3 by the fuel pump 12 is provided.
The fuel supply device 13 includes a fuel tank 11, a fuel pump 12, a pressure adjustment valve 14, an orifice 15, a fuel gallery pipe 16, a fuel supply pipe 17, a fuel return pipe 18, a jet pump 19, and a fuel transfer pipe 20. The

The fuel pump 12 is an electric pump that rotationally drives a pump impeller with a motor, and is disposed in the fuel tank 11.
One end of the fuel supply pipe 17 is connected to the discharge port of the fuel pump 12, the other end of the fuel supply pipe 17 is connected to the fuel gallery pipe 16, and the fuel supply port of the fuel injection valve 3 is connected to the fuel gallery pipe 16. Connected.

In the fuel tank 11, the fuel return pipe 18 branches from the fuel supply pipe 17, and the other end of the fuel return pipe 18 is opened in the fuel tank 11.
In the fuel return pipe 18, a pressure regulating valve 14, an orifice 15, and a jet pump 19 are interposed in order from the upstream side.
The pressure adjustment valve 14 is generally configured by a valve body 14a that opens and closes the fuel return pipe 18 and an elastic member 14b such as a coil spring that presses the valve body 14a toward the valve seat upstream of the fuel return pipe 18. The pressure adjustment valve 14 opens when the fuel pressure supplied to the fuel injection valve 3 exceeds the minimum pressure FPMIN, and closes when the fuel pressure is equal to or lower than the minimum pressure FPMIN.

  As described above, the pressure adjustment valve 14 opens when the fuel pressure supplied to the fuel injection valve 3 becomes higher than the minimum pressure FPMIN, but the fuel return is performed by the orifice 15 provided on the downstream side of the pressure adjustment valve 14. Since the flow rate of fuel returned to the fuel tank 11 through the pipe 18 is reduced, the amount of fuel discharged from the fuel pump 12 is increased beyond the return flow rate so that the pressure exceeds the minimum pressure FPMIN. The fuel pressure can be increased up to.

In other words, by controlling the discharge amount of the fuel pump 12 based on the predetermined minimum pressure FPMIN adjusted by the pressure regulating valve 15, the fuel pressure is set to a target value (target value ≧ The pressure can be increased to FPMIN).
Note that the amount of fuel (relief flow rate) returned to the fuel tank 11 by the fuel return pipe 18 is reduced to such an extent that the fuel pressure exceeding the predetermined minimum pressure FPMIN can be increased by controlling the discharge amount of the fuel pump 12. For example, the pressure regulating valve 14 may have a function of reducing the flow rate without providing the orifice 15.

The jet pump 19 transfers fuel through the fuel transfer pipe 20 by the flow of fuel returned into the fuel tank 11 through the pressure regulating valve 14 and the orifice 15.
The fuel tank 11 is a so-called bowl-shaped fuel tank in which a part of the bottom surface is raised and the bottom space is divided into two regions 11a and 11b, and the suction port of the fuel pump 12 opens into the region 11a. If the fuel in the region 11b is not transferred to the region 11a side, the fuel in the region 11b will remain.

Therefore, the jet pump 19 applies a negative pressure to the fuel transfer pipe 20 by the flow of fuel returned into the region 11a of the fuel tank 11 via the pressure regulating valve 14 and the orifice 15, and the fuel transfer pipe 20 is opened. The fuel in the region 11b to be conducted is guided to the jet pump 19 through the fuel transfer pipe 20, and is discharged into the region 11a together with the return fuel.
An ECM (engine control module) 31 including a microcomputer is provided as an engine control unit that controls fuel injection by the fuel injection valve 3, ignition operation by the spark plug 6, opening of the electronic control throttle 10, and the like.

Further, an FPCM (fuel pump control module) 30 having a microcomputer is provided as a fuel pump control unit for outputting the drive output of the fuel pump 12.
The ECM 31 and the FPCM 30 are configured to be able to communicate with each other. From the ECM 31 to the FPCM 30, a square wave pulse signal PINS, which is an instruction signal of the driving duty and driving frequency of the fuel pump 12, is transmitted from the FPCM 30 to the ECM 31. Thus, diagnostic information such as a communication error is transmitted.

The driving duty in the present application is an on-time ratio in one cycle. The larger the driving duty, the higher the applied voltage of the fuel pump 12 and the higher the rotational speed of the fuel pump 12, so that the driving duty is changed. Thus, the discharge amount of the fuel pump 12 is changed, and the fuel pressure supplied to the fuel injection valve 3 is controlled.
The ECM 31 includes a fuel pressure sensor (fuel pressure detection means) 33 for detecting a fuel pressure FUPR (discharge pressure of the fuel pump 12 and fuel supply pressure to the fuel injection valve 3) in the fuel gallery pipe 16, and depression of an accelerator pedal (not shown). An accelerator opening sensor 34 for detecting the amount (accelerator opening) ACC, an air flow sensor 35 for detecting the intake air flow rate QA of the internal combustion engine 1, a rotation sensor 36 for detecting the rotational speed NE of the internal combustion engine 1, and cooling of the internal combustion engine 1 From a water temperature sensor 37 that detects a water temperature TW (engine temperature), an oxygen sensor 38 that detects a rich / lean RL with respect to the stoichiometric air-fuel ratio (target air-fuel ratio) of the air-fuel ratio of the internal combustion engine 1 according to the oxygen concentration in the exhaust gas, etc. The detection signal is input.
Instead of the oxygen sensor 38, an air-fuel ratio sensor that generates an output corresponding to the air-fuel ratio may be provided.

  The ECM 31 calculates the basic injection pulse width TP based on the intake air flow rate QA and the engine speed NE, and corrects the basic injection pulse width TP according to the fuel pressure FUPR at that time, while based on the output of the oxygen sensor 38. The air-fuel ratio feedback correction coefficient LAMBDA for calculating the actual air-fuel ratio close to the target air-fuel ratio is calculated, and the basic injection pulse width TP corrected according to the fuel pressure FUPR is further corrected with the air-fuel ratio feedback correction coefficient LAMBDA. The final injection pulse width TI is calculated.

At the injection timing of each cylinder, an injection pulse signal having an injection pulse width TI is output to the fuel injection valve 3 to control the fuel injection amount and the injection timing by the fuel injection valve 3.
Further, the ECM 31 calculates an ignition timing (ignition advance value) based on the basic injection pulse width TP indicating the load of the internal combustion engine 1 and the engine speed NE, and spark discharge by the spark plug 6 is performed at the ignition timing. In this manner, the energization to the ignition coil (not shown) is controlled.

Further, the ECM 31 calculates the target opening of the electronically controlled throttle 10 from the accelerator opening ACC or the like, and drives and controls the throttle motor 9 so that the actual opening approaches the target opening.
Further, the ECM 31 determines the driving duty and driving frequency of the fuel pump 12 based on the fuel pressure FUPR detected by the fuel pressure sensor 33 and the engine operating conditions, and the duty (duty ratio) corresponding to these driving duty and driving frequency. ) And a square wave pulse signal PINS having a frequency is transmitted to the FPCM 30 as an instruction signal for the driving duty / driving frequency of the fuel pump 12.

The FPCM 30 determines and outputs a drive output of the fuel pump 12 based on the pulse signal PINS received from the ECM 31 side. That is, the ECM 31 and the FPCM 30 constitute a fuel pump control system.
Hereinafter, the fuel pump control function of the ECM 31 and the fuel pump control function of the FPCM 30 will be described in detail.

The routine shown in the flowchart of FIG. 2 shows the fuel pump control function in the ECM 31, and this routine is interrupted at regular intervals.
First, in step S101, in addition to the detection signal of the fuel pressure sensor 33, various sensor signals indicating the operating conditions (engine load, engine speed, engine temperature, etc.) of the internal combustion engine 1 are input.

In the next step S102, the target fuel pressure TGFUPR is calculated based on the engine operating condition input in step S101. For example, the target fuel pressure TGFUPR is set higher as the load becomes higher and the rotation speed is higher, and is set higher than that at the time of cold start when the high temperature restart is performed.
In step S103 (drive duty calculation means), a drive duty DUTY (on-time ratio) in the duty control of the fuel pump 12 is calculated so that the fuel pressure FUPR detected by the fuel pressure sensor 33 approaches the target fuel pressure TGFUPR.

Furthermore, in step S104, the drive frequency f in the duty control of the fuel pump 12 is calculated.
The drive frequency f may be a fixed value, or, for example, as disclosed in Japanese Patent Application Laid-Open No. 2008-2332099, the drive frequency f may be increased (the cycle is shortened) as the drive duty DUTY is decreased. .

In step S105 (conversion means, instruction output means), based on the drive duty DUTY and the drive frequency f, the output waveform (ON time T1, period of the pulse signal PINS for instructing the drive duty DUTY and the drive frequency f to the FPCM 30 side. T2) is determined, and the pulse signal PINS having the determined output waveform is transmitted to the FPCM 30.
The processing content in step S105 will be described in detail with reference to FIGS.

FIG. 3 shows a table for converting the drive frequency f into the cycle T2 (ms) of the instruction pulse signal PINS, and the drive frequency f is selected from any of the three types (5 kHz, 10 kHz, 20 kHz). Is illustrated.
The drive frequency f is a frequency required when the fuel pump 12 is duty-controlled, and the instruction pulse signal PINS does not need to be a signal having the same frequency as the drive frequency f, and the instruction pulse signal PINS When the frequency becomes higher, it becomes difficult to determine the presence or absence of noise influence on the pulse signal PINS.

Therefore, the conversion characteristics between the drive frequency f and the cycle T2 are set so that the cycle T2 longer than the cycle corresponding to the drive frequency f is set. In other words, the drive frequency f of the fuel pump 12 is converted to a lower frequency, and the frequency after the conversion is used as the frequency of the pulse signal PINS transmitted from the ECM 31 to the FPCM 30.
Specifically, when the driving frequency f = 5 kHz, the cycle T2 = 2.0 ms, when the driving frequency f = 10 kHz, the cycle T2 = 1.8 ms, and when the frequency f = 20 kHz, the cycle T2 = 1.6 ms.
Although FIG. 3 shows a conversion table, the drive frequency f can be converted into the cycle T2 by an arithmetic expression.

  The numerical values of the driving frequency f and the period T2 are examples, and can be changed as appropriate. The period T2 may be increased as the driving frequency f increases, and the period T2 increases uniformly with changes in the driving frequency f. -It is not necessary to decrease, and it may be converted to a different cycle T2 for each drive frequency f.

On the FPCM 30 side, as will be described later, a table / calculation formula that converts the drive frequency f on the ECM 31 side into the cycle T2 and converts the cycle T2 of the transmitted pulse signal PINS back to the drive frequency f. The indication value of the pump drive frequency f can be detected from the cycle T2 of the pulse signal PINS sent from the ECM 31 side.
FIG. 4 shows a table for converting the drive duty DUTY into the ON time T1 (duty) of the instruction pulse signal PINS.

In the conversion table of FIG. 4, the drive duty DUTY = 0% is converted to the on time T1 = 0.16 ms, the drive duty DUTY = 100% is converted to the on time T1 = 1.44 ms, and the drive between 0% and 100% is performed. With respect to the duty DUTY, the ON time T1 increases and decreases proportionally between 0.16 ms and 1.44 ms.
The on time T1 = 1.44 ms corresponding to the drive duty DUTY = 100% is set to a time shorter than the cycle (minimum cycle) at the maximum frequency of the instruction pulse signal PINS.

  That is, by converting the drive duty DUTY = 0% to the on time T1 longer than 0, the instruction pulse signal PINS does not become a low level sticking state (off-continuation state) at normal time, and the drive By setting the ON time T1 corresponding to the duty DUTY = 100% to a time shorter than the cycle (minimum cycle) at the maximum frequency of the instruction pulse signal PINS, the pulse signal PINS is in a high level sticking state ( The pulse wave (square wave) always repeats on and off.

In other words, the conversion of FIG. 4 is to convert the driving duty DUTY of the fuel pump 12 set to 0% ≦ DUTY ≦ 100% into a duty of 0% <DUTY <100%. For example, the duty of PINS is set to 20% ≦ instruction pulse signal PINS duty ≦ 80%.
Here, the minimum value of the duty (ON time T1) of the instruction pulse signal PINS and the maximum value of the duty (ON time T1) of the instruction pulse signal PINS, that is, the variable range of the duty of the instruction pulse signal PINS is: The sampling cycle (resolution) in the FPCM 30 that inputs the instruction pulse signal PINS after A / D conversion, the signal characteristics when noise is superimposed on the instruction pulse signal PINS, and the drive duty of the fuel pump 12 are required. Based on the minimum resolution or the like, it is previously adapted to a value that can transmit information on the pump drive duty to the FPCM 30 and can diagnose a duty abnormality due to noise superposition or the like.

  For example, when the duty of the instruction pulse signal PINS input by the FPCM 30 exceeds the maximum setting value of the instruction pulse signal PINS due to noise superposition, the noise component is generated during the ON period of the instruction pulse signal PINS. It can be presumed that the ON period has been extended due to the overlap, and the smaller the maximum duty of the instruction pulse signal PINS, the easier it is to exceed the maximum duty when noise components overlap, and the detection accuracy of noise superposition increases. By reducing the maximum duty of the instruction pulse signal PINS, the variable range of the duty of the instruction pulse signal PINS is narrowed, and the resolution of the pump drive duty on the FPCM 30 side is reduced.

  In addition, when the duty of the instruction pulse signal PINS input by the FPCM 30 is lower than the minimum setting value of the instruction pulse signal PINS, the minimum value of the instruction pulse signal PINS is set during the OFF period of the instruction pulse signal PINS. It can be estimated that on-time noise below the on-time is superimposed, and the larger the minimum duty of the instruction pulse signal PINS, the easier it is to detect the occurrence of the ON period with the noise component alone, but the instruction pulse signal PINS By increasing the minimum duty, the variable range of the duty of the instruction pulse signal PINS is narrowed, and the resolution of the pump driving duty on the FPCM 30 side is reduced.

Therefore, the minimum value of the duty of the instruction pulse signal PINS (ON time T1) and the duty of the instruction pulse signal PINS (ON time T1) are set so that both the diagnostic accuracy of noise superimposition and the resolution of the pump drive duty are compatible. ) Maximum value is adapted.
Although FIG. 4 shows a conversion table, the drive duty DUTY can be converted into the on-time T1 by an arithmetic expression.

When the ON time T1 indicating the duty of the instruction pulse signal PINS and the cycle T2 of the instruction pulse signal PINS are determined as described above, a square wave having the ON time T1 and the cycle T2 is driven as shown in FIG. The signal is transmitted to the FPCM 30 as an instruction pulse signal PINS indicating the duty and the driving frequency.
The routine shown in the flowchart of FIG. 6 shows the fuel pump control function in the FPCM 30. This routine is interrupted for each A / D input of the instruction pulse signal PINS, for example.

First, in step S201, the A / D conversion value of the analog instruction pulse signal PINS transmitted from the ECM 31 is read and converted into a digital signal.
In step S202 (duty calculation means, reconversion means), the on time T1 and cycle T2 of the digitized instruction pulse signal PINS are calculated, and the on time T1 and cycle T2 are calculated as the drive duty and drive frequency of the fuel pump 12. The process of returning to (reconversion process) is performed.

The process of converting the digitized on-time T1 of the instruction pulse signal PINS into the on-time T3 indicating the fuel pump drive duty is performed by a conversion table as shown in FIG. 7 (an arithmetic expression having the conversion characteristics shown in the conversion table). Based on.
As described above, the maximum value of the on-time T1 of the instruction pulse signal PINS is set to a constant value (T1 = 1.44 ms) regardless of the cycle T2, and T1 = 1.44 ms is the fuel pump driving duty = 100%. The on-time T3 corresponding to the fuel pump driving duty = 100% differs depending on the fuel pump driving frequency. When T1 = 1.44 ms, the fuel pump driving cycle is set to the on-time T3. There is a need.

On the other hand, when the ON time T1 of the instruction pulse signal PINS is the minimum value (ON time T1 = 0.16 ms), 0% is instructed as the fuel pump driving duty regardless of the fuel pump driving frequency. Will be.
Therefore, the conversion table converts T1 = 1.44 ms to an on time T3 that matches the fuel pump driving cycle, converts T1 = 0.16 ms to an on time T3 = 0, and T1 = 0.16 ms to T1 = 1.44 ms. Until the ON time T3 is proportionally increased or decreased.

A plurality of conversion tables (calculation formulas) for converting the on-time T1 to the on-time T3 are prepared in advance for each driving frequency, and according to the fuel pump driving frequency f determined from the cycle T2 of the instruction pulse signal PINS. A conversion table (arithmetic expression) used for conversion is selected, and the on-time T1 is converted into the on-time T3 using the selected conversion table (arithmetic expression).
Further, the process of converting the digitized period T2 of the instruction pulse signal PINS into the fuel pump driving period T4 is based on a conversion table as shown in FIG. 8 (an arithmetic expression having the conversion characteristics shown in the conversion table). Done.

  As described above, on the ECM 31 side, any one of 5 kHz, 10 kHz, and 20 kHz is selected as the fuel pump drive frequency. Is set to 1.8 ms, and the period T2 of the pulse signal PINS is set to 1.6 ms when the frequency is 20 kHz. Therefore, it is determined whether the cycle T2 of the pulse signal PINS is 2.0 ms, 1.8 ms, or 1.6 ms. It can be determined which of 5 kHz, 10 kHz, and 20 kHz is designated as the pump driving frequency.

  Furthermore, since the period T4 at the frequency = 5 kHz is 200 μs, the period T4 at the frequency = 10 kHz is 100 μs, and the period T4 at the frequency = 10 kHz is 50 μs. Therefore, if the period T2 is 2.0 ms, the period T4 is set to 200 μs, and the period T2 The conversion table (calculation formula) is set so that the period T4 is 100 μs if the period T2 is 1.8 ms, and the time T4 is 50 μs if the period T2 is 1.6 ms.

  T2 = 2.0 ms, 1.8 ms, and 1.6 ms in the conversion table (calculation formula) includes a case where the error is within an allowable error, and the time T4 can be normally set for a pulse signal PINS that has no abnormality such as noise superposition. As described above, the allowable range is adapted based on the A / D conversion period of the pulse signal PINS, and specifically, for example, the standard value +0.1 ms and the standard value minus 0.1 ms are set within the allowable range.

  By the way, when the ON time T1 of the pulse signal PINS is out of the setting range of 0.16 ms to 1.44 ms, in other words, the duty of the pulse signal PINS deviates from the setting range and includes 0% below the setting range. When it corresponds to a region or a region including 100% exceeding the set range, and furthermore, when the period T2 of the pulse signal PINS does not correspond to any of the vicinity of 2.0 ms, 1.8 ms, or 1.6 ms In the process of being transmitted from the ECM 31 to the FPCM 30, a problem such as noise being superimposed on the pulse signal PINS occurs, so that it can be estimated that the duty and / or cycle of the pulse signal PINS deviates from the set value.

Therefore, in step S202, the presence / absence of an abnormality in the pulse signal PINS is diagnosed. When the occurrence of the abnormality is diagnosed, a predetermined fail-safe process is executed.
Details of the abnormality diagnosis and fail-safe processing will be described with reference to the flowchart of FIG.
First, in step S301 (diagnostic means), it is determined whether or not the on-time T1 of the digitized pulse signal PINS is normal.

As described above, since the setting range of the on time T1 is 0.16 ms to 1.44 ms, when it deviates from this range by a predetermined value or more, as a result of noise being superimposed on the pulse signal PINS, the on time T1 (duty ) Deviates from the set range.
The amount of deviation from the set range (0.16 ms to 1.44 ms) is determined to be abnormal, so that it is adapted not to be diagnosed as abnormal due to a measurement error due to the A / D conversion period of the pulse signal PINS, for example, An allowable range of 0.1ms is set before and after the set range (0.16ms to 1.44ms), and if the on time T1 is within 0.06ms to 1.54ms (0.06ms ≤ T1 ≤ 1.54ms), it is judged normal and the on time If T1 is outside 0.06 ms to 1.54 ms (0.06 ms> T1 or T1> 1.54 ms), it is determined as abnormal.

For example, when a pulse having an ON time that is less than the minimum time (0.16 ms) of the time T1 is generated as a noise component in the OFF period of the pulse signal PINS, the ON time due to the noise is measured as the ON time T1, and this ON time T1 Is smaller than the minimum time (0.16ms), it is judged as abnormal.
In addition, noise is superimposed near the rise or fall of the ON period of the pulse signal PINS, so that the pulse signal PINS rises before the original rise position or falls after the original fall position. Since the ON period of the pulse signal PINS is longer than the setting, when the ON time T1 longer than the maximum of the ON time T1 is measured, the extension of the ON time T1 is the noise superposition. It can be determined that

  If the on-duty of the pulse signal PINS is set in the range of 0% to 100%, it is impossible to detect the on-time T1 due to noise superposition and the short on-time T1 due to noise superposition. By limiting the on-duty of the signal PINS to a range (0.16 to 1.44 ms) narrower than 0% (0 ms) to 100% (1.6 to 2.0 ms), it is possible to detect noise superposition as described above.

If it is determined that the on-time T1 is normal, the process proceeds to step S302, and it is determined whether the cycle T2 of the digitized pulse signal PINS, that is, the frequency of the pulse signal PINS is normal.
In step S302, as described above, when the period T2 does not correspond to any of the vicinity of 2.0 ms, the vicinity of 1.8 ms, and the vicinity of 1.6 ms, noise is superimposed, which is different from the original rising / falling positions. It is estimated that a rise or fall has occurred at the position, and it is determined that the pulse signal PINS is abnormal.

On the other hand, if the period T2 is in the vicinity of 2.0 ms, 1.8 ms, or 1.6 ms, it is determined that the FPCM 30 has received the pulse signal PINS with the set period (frequency), and the pulse signal It is determined that PINS is normal.
As described above, by diagnosing whether or not the duty and frequency of the pulse signal PINS are normal, even if the frequency (period T2) is normal, the ON time T1 is increased due to noise superposition, the pulse signal PINS The abnormality of the pulse signal PINS can be diagnosed from the occurrence of the on-time T1 due to a noise component that is less than the minimum on-time, and even if the on-time T1 is normal, the change in the cycle T2 caused by noise superimposition is diagnosed as abnormal The state affected by noise can be diagnosed with high accuracy.

If both the on-time T1 and the cycle T2 are normal, the process proceeds to step S303, and T1 and T2 are converted into the fuel pump drive duty T3 and the drive cycle T4 according to the conversion tables (calculation formulas) shown in FIGS. To do.
On the other hand, if it is determined in step S301 that the on-time T1 is abnormal, the process proceeds to step S304, and if it is determined in step S302 (diagnostic means) that the period T2 is abnormal, the process proceeds to step S304. . In other words, if at least one of the on-time T1 (duty) and the cycle T2 (frequency) is abnormal, the process proceeds to step S304.

In step S304, it is determined whether or not the continuation time TCO in which at least one of the on-time T1 and the cycle T2 is abnormal exceeds the upper limit time TMAX.
The upper limit time TMAX is a maximum allowable time for continuing the clamping process of an on-time T3 and a period T4, which will be described later. For example, if the clamping process is excessively long, the fuel pressure is changed due to a change in engine load and engine speed during that period. May become insufficient and may lead to insufficient injection amount. Therefore, the maximum time that does not cause insufficient injection amount even if there is a change in engine load / engine speed, in other words, for the first time, the abnormality of the pulse signal PINS The upper limit time TMAX is preliminarily adapted as the maximum time during which the operation amount of the fuel pump 12 at the determined time can be maintained as it is.

If the time TCO during which the abnormality of the pulse signal PINS continues is within the upper limit time TMAX, the process proceeds to step S305 (failure means), and T1, T2 immediately before abnormality diagnosis, in other words, normal determination is made. T3 and T4 obtained by converting the latest values of the times T1 and T2 are set as the drive duty and drive cycle used for drive control of the fuel pump 12.
Therefore, if the abnormal continuation time is within the upper limit time TMAX, it is clamped at T1 and T2 (T3 and T4 converted from T1 and T2) immediately before the abnormality diagnosis, and during that time, the operation amount of the fuel pump 12 is constant. Will be retained.

If the abnormality of the pulse signal PINS due to noise or the like is temporary, and the pulse signal PINS (T1, T2) returns to normal within the upper limit time TMAX, the process proceeds from step S301 to step S303 again. Based on the latest ON time T1 and period T2 of the pulse signal PINS, the pump drive duty and the pump drive frequency are updated.
On the other hand, if the abnormality of the pulse signal PINS (T1, T2) continues beyond the upper limit time TMAX, the process proceeds from step S304 to step S306 (fail means), and the drive duty and drive frequency of the fuel pump 12 are changed. When the abnormality is detected in the pulse signal PINS (T1, T2) after that, the drive duty T3FS and the drive frequency T4FS for failsafe are continuously used. Like that.

That is, if the abnormality (such as noise superimposition) of the pulse signal PINS continues beyond the upper limit time TMAX, the fuel pump 12 is driven at a fixed operation amount with the drive duty and drive frequency of the fuel pump 12 as fixed values stored in advance. To do.
In step S305, the clamping process is a process of clamping to the on-time T1 and the period T2 immediately before the occurrence of an abnormality. For example, an operating condition (for example, a low load / low rotation range) in which a low value is set as the driving duty immediately before the occurrence of an abnormality. ), If the transient operation toward the high load / high rotation side is performed while the abnormality continues, the retained drive duty becomes lower than the drive duty that can maintain the target fuel pressure, and the injection amount is insufficient. Will be generated.

Therefore, when the abnormality of the pulse signal PINS (T1, T2) continues beyond the upper limit time TMAX, a driving duty that is adapted in advance so as to ensure an injection amount in a region that allows operation in a fail-safe state. Switch to T3FS and drive frequency T4FS to ensure minimum drivability.
When an abnormality of the pulse signal PINS is detected, the process may be uniformly advanced to step S306 to fix the drive duty T3FS and the drive frequency T4FS for fail-safe in advance. Even when the operation returns to normal, there may be a case where the drive duty / drive frequency set on the ECM 31 side is switched to a value with a large difference, and fuel pressure fluctuations and the like are unnecessarily generated. .

Therefore, as in the above-described embodiment, it is clamped to a value immediately before the occurrence of the abnormality to determine whether or not the abnormality of the pulse signal PINS converges, and if the abnormality continues, if the abnormality continues, the drive duty T3FS for fail safe, It is preferable to fix the driving frequency to T4FS.
When the abnormality of the pulse signal PINS (T1, T2) is diagnosed as described above and the drive duty (ON time T3) and the drive frequency (cycle T4) are determined according to the diagnosis, step S203 (pump output means) Then, whether the drive signal (drive output) of this drive duty and drive frequency is output to a drive circuit (switching element) separate from the FPCM 30 that drives the fuel pump 12, and the power supply to the fuel pump 12 is duty controlled. Alternatively, when the FPCM 30 includes the drive circuit, the drive voltage (drive output) obtained by driving the switching element with the drive signal having the drive duty and drive frequency is output to the fuel pump 12.

  When the FPCM 30 determines an abnormality in the pulse signal PINS (an abnormality that continues beyond the upper limit time TMAX), the FPCM 30 transmits an abnormality determination result to the ECM 31 side. A process of limiting the driving range of 1 to a predetermined low / medium load range, a process of warning the driver of the occurrence of an abnormality by lighting a warning lamp, or the like is performed. The limitation of the operation region can be realized by limiting the opening of the electronic control throttle 10 or the like.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) an engine control unit for controlling a fuel injection valve of the engine and calculating an indication value of a drive duty and a drive frequency in a drive control of a fuel pump that pumps fuel to the fuel injection valve; and the drive duty and the drive frequency A fuel pump control system including a fuel pump control unit that receives the indicated value from the engine control unit and outputs a drive output of the fuel pump,
The engine control unit converts the drive duty to an instruction duty in an intermediate range excluding at least 0% and 100%, and converts the drive frequency to a lower instruction frequency. The instruction duty and the instruction frequency Is output to the fuel pump control unit as an instruction signal of the drive duty and drive frequency,
The fuel pump control unit converts the duty of the pulse signal into an indication value of the driving duty, converts the frequency of the pulse signal into the driving frequency, and based on the driving duty and the driving frequency obtained by the conversion, A fuel pump that determines the drive output and switches the drive output to the drive output for fail when the presence or absence of abnormality of the pulse signal is diagnosed based on the duty and frequency of the pulse signal. Control system.

  According to the above configuration, since the duty of the pulse signal transmitted from the engine control unit to the fuel pump control unit is limited to the duty in the intermediate range, the presence or absence of noise superimposition on the pulse signal in the fuel pump control unit can be easily distinguished, When an abnormality occurs in the pulse signal, the drive output is switched to the drive output for fail to suppress outputting an abnormal drive output.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 3 ... Fuel injection valve, 11 ... Fuel tank, 12 ... Fuel pump, 14 ... Pressure regulator, 15 ... Fuel gallery piping, 16 ... Fuel supply piping, 17 ... Fuel return piping, 30 ... FPCM (fuel * Pump control module), 31 ... ECM (engine control module), 33 ... Fuel pressure sensor

Claims (3)

A signal indicating a drive duty of the fuel pump is sent to a fuel pump control unit that controls a fuel injection valve of the engine and outputs a drive output for driving a fuel pump that pumps fuel to the fuel injection valve. An engine control unit for output,
Driving duty calculating means for calculating the driving duty;
Conversion means for converting the drive duty into a duty in an intermediate region excluding at least 0% and 100%;
An instruction output means for outputting the converted pulse signal of the duty to the fuel pump control unit as a signal indicating the drive duty;
Engine control unit with A fuel pump control system comprising: the engine control unit according to claim 1; and a fuel pump control unit that inputs a pulse signal output from the engine control unit and outputs a drive output for driving the fuel pump. ,
The fuel pump control unit comprises:
Duty calculating means for calculating the duty of the input pulse signal;
Re-converting means for converting the duty calculated by the duty calculating means into drive duty;
A pump output means for outputting a drive output of the fuel pump based on a drive duty obtained by the conversion by the reconversion means;
A fuel pump control system comprising: The fuel pump control unit comprises:
A diagnostic means for determining normality / abnormality of the pulse signal by comparing the duty and frequency of the input pulse signal and their normal ranges;
Fail means for clamping the drive output output by the pump output means to a fail output when the diagnostic means determines that the pulse signal is abnormal,
The fuel pump control system according to claim 2, further comprising:

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