JP4317842B2 - Abnormality judgment device for pressure state detection device - Google Patents

Description

  The present invention relates to an abnormality determination device for a pressure state detection device that determines an abnormality of a pressure state detection device that detects a pressure state in a cylinder of an internal combustion engine.

  As a conventional abnormality determination device for an in-cylinder pressure sensor, for example, one disclosed in Patent Document 1 is known. This internal combustion engine is a 4-cylinder gasoline engine, and an in-cylinder pressure sensor is provided in each cylinder. The in-cylinder pressure sensor is attached to the spark plug and detects the pressure in the cylinder (hereinafter referred to as “in-cylinder pressure”). In this abnormality determination device, the abnormality determination of the in-cylinder pressure sensor is performed as follows during the fuel cut of the internal combustion engine. First, the indicated mean effective pressure is calculated based on the in-cylinder pressure detected by the in-cylinder pressure sensor. In parallel with this, the indicated mean effective pressure to be obtained is estimated based on the rotational speed of the internal combustion engine. When the absolute value of the deviation between the two indicated mean effective pressures obtained as described above exceeds a predetermined value, it is determined that an abnormality has occurred in the in-cylinder pressure sensor.

  However, the conventional abnormality determination device may not be able to appropriately determine abnormality of the in-cylinder pressure sensor. For example, in a piezoelectric element type in-cylinder pressure sensor generally used as an in-cylinder pressure sensor, even if the actual in-cylinder pressure is the same, the detected in-cylinder pressure changes according to the tightening degree of the piezoelectric element to the mounting portion, The lower the degree, the smaller. If the detected in-cylinder pressure greatly deviates from the actual in-cylinder pressure due to this, in the conventional abnormality determination device, the indicated mean effective pressure calculated based on the in-cylinder pressure is too small or too large, and is estimated. Since the deviation from the indicated mean effective pressure increases, even if the in-cylinder pressure sensor is normal, it is erroneously determined to be abnormal.

  Such an erroneous determination also occurs when a gain change or drift occurs in the in-cylinder pressure sensor. That is, even if a gain change or drift occurs due to the degree of tightening of the in-cylinder pressure sensor, individual differences, deterioration over time, etc., if the waveform is normal, the true value of the detected in-cylinder pressure is obtained by correction such as learning. Therefore, it is not always necessary to determine that there is an abnormality. However, in the conventional abnormality determination device, the indicated average effective pressure is calculated to be excessively low or excessively based on the detected in-cylinder pressure, so that it is determined as abnormal. In addition, even if there is an abnormal disturbance in the waveform, the indicated mean effective pressure may be calculated as a value that is not different from that in the normal state. It is misjudged that there is. Such a waveform abnormality can be avoided by, for example, using a cylinder pressure sensor with higher detection accuracy and appropriately mounting it, but such a sensor is generally very expensive, Increases manufacturing costs.

  Further, in the conventional abnormality determination device, the indicated mean effective pressure calculated based on the in-cylinder pressure is normal even when an abnormality in which the phase of the output of the in-cylinder pressure sensor is greatly shifted (hereinafter referred to as “offset abnormality”) occurs Unless it deviates greatly with respect to that of time, it is not determined to be abnormal, so that it is not possible to appropriately determine abnormality.

  The present invention has been made to solve such a problem, and provides an abnormality determination device for a pressure state detection device that can appropriately determine an abnormality including a waveform abnormality of the pressure state detection device. Objective.

Japanese Patent Laid-Open No. 8-246941

In order to achieve this object, the invention according to claim 1 is a pressure state detection device that detects a pressure state in the cylinder 3a of the internal combustion engine 3 (in-cylinder pressure PCYL in the embodiment (hereinafter, the same in this section)). In-cylinder pressure sensor 10, ECU 2) abnormality determination device 1, fuel supply stop means (injector 6, ECU 2) for stopping fuel supply to internal combustion engine 3 during operation of internal combustion engine 3, and fuel supply stop means Based on the pressure state detected when the fuel supply to the internal combustion engine 3 is stopped by the above, a plurality of vectors θ each representing the increase / decrease direction and the degree of increase / decrease of the pressure state between the compression stroke and the expansion stroke are continuously provided. a plurality of vectors representing the difference vector calculating means (ECU 2, step 5) and present value of the plurality of vectors calculated θ (n) and the previous value θ and (n-1) for calculating manner Vector deviation calculating means for continuously calculating the difference d [theta] (ECU 2, step 6) and, on the basis of transition of a plurality of vectors θ and vector deviation d [theta] calculated, the detected pressure state first and second inflection Inflection point timing calculating means (ECU2, steps 7, 8, 16, 17) for calculating the timing at which the points IP1 and IP2 are reached, the calculated first and second inflection point timings and predetermined first and first inflection points. An abnormality determining means (ECU2, steps 28 to 30 ) for determining a waveform abnormality of the pressure state detection device by comparing two timings, respectively .

According to the abnormality determination device of the pressure condition detecting apparatus, based on the detected pressure conditions in a pressure state detection device in the fuel cut stopping the supply of fuel to the internal combustion engine, during the period from the compression stroke to the expansion stroke A plurality of vectors each representing the increase / decrease direction and the degree of increase / decrease of the pressure state in are continuously calculated , and a plurality of vector deviations representing the difference between the current value and the previous value of these vectors are continuously calculated . Further, the timing at which the detected pressure state reaches the first and second inflection points is calculated based on the calculated vector and vector deviation . Then, the waveform abnormality of the pressure state detection device is determined by comparing the calculated first and second inflection point timings with predetermined first and second timings, respectively .

Since the combustion is not performed during the fuel cut, the influence of the pressure fluctuation caused by the combustion is excluded from the pressure state detected at that time. Further, each of the calculated vector and the vector deviation as described above, show the changes direction and decreasing rate of the pressure state for each predetermined period, therefore, the transition of the plurality of vectors and vector deviation is calculated continuously Represents the pressure state waveform.

For this reason, when there is an abnormal disturbance in the waveform, the vector and the vector deviation do not change normally, so that it is possible to appropriately determine that the pressure state detection device is abnormal. Also, when a gain change or drift occurs, the value of the pressure state itself will fluctuate, but as long as the waveform is kept normal, the vector and vector deviation will change normally. Appropriately determined as normal.

As described above, the vector and the vector deviation represent the increase / decrease direction and the degree of increase / decrease of the detected pressure state, and the transition of the vector and vector deviation represents the waveform of the pressure state. Therefore, for example, when the pressure state monotonously increases or decreases between the minimum value and the maximum value of the detected pressure state, the timing at which the vector reaches the maximum value or the minimum value is set to the first value . Alternatively, it can be calculated as the second inflection point timing. Further, during the fuel cut, the timing at which the first and second inflection points in the pressure state actually appear is roughly determined. Thus, for example, and sets such a time as the predetermined first and second timing, largely deviated the first and second inflection point timing calculated for a given first and second timing set In the case where there is an abnormality, the waveform of the pressure state detection device is abnormally disturbed, and it can be determined that the waveform abnormality has occurred. Thus, by comparing the first and second inflection point timings with the predetermined first and second timings, it is possible to quantitatively grasp the transition state between the minimum value and the maximum value of the pressure state. Thus, it is possible to appropriately determine the waveform abnormality.

The invention according to claim 2 is the abnormality determination device 1 of the pressure state detection device according to claim 1, wherein the top dead center timing (reference value CATDCES) at which the piston 3b of the internal combustion engine 3 reaches the top dead center (TDC). further comprising a dead center timing detecting means on detecting (ECU 2), and the abnormality determining means, on the basis of transition of the vector θ and vector deviation d [theta], peak timing a peak of the detected pressure states to calculate the peak timing generated Computation means (ECU2, step 11) is provided, and the offset abnormality of the pressure state detection device is determined by comparing the detected top dead center timing with the calculated peak timing.

  According to this configuration, the abnormality determining means generates the timing at which the piston of the internal combustion engine detected by the top dead center timing detecting means reaches the top dead center and the peak of the pressure state calculated by the peak timing calculating means. By comparing the timing, an offset abnormality is determined.

When the pressure state is at a peak, the pressure state does not change, so the vector has a value of zero. Therefore, based on the transition of the vector , the timing at which the value is 0 and the positive value is switched to the negative value can be calculated as the timing at which the detected pressure state peak occurs. Further, as described above, during the fuel cut, the influence of pressure fluctuation caused by combustion is eliminated, so the actual pressure state peaks when the piston of the internal combustion engine reaches top dead center. . Therefore, when the calculated peak timing is largely deviated from the top dead center timing, it can be determined that the phase of the output of the pressure state detection device is largely deviated and an offset abnormality has occurred. . Thus, by comparing the peak timing with the top dead center timing, it is possible to appropriately determine the offset abnormality.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of an abnormality determination device 1 according to an embodiment of the present invention and an internal combustion engine (hereinafter referred to as “engine”) 3 to which the abnormality determination device 1 is applied. The engine 3 is, for example, a diesel engine mounted on a vehicle (not shown), and has four cylinders 3a (only one is shown). A combustion chamber 3e is formed between the piston 3b and the cylinder head 3c of each cylinder 3a.

  An intake pipe 4 and an exhaust pipe 5 are respectively connected to the cylinder head 3c, an intake valve 4a and an exhaust valve 5a are provided, and a fuel injection valve (hereinafter referred to as “injector”) 6 faces the combustion chamber 3e. It is attached. The fuel injection amount and timing of the injector 6 are controlled by a drive signal from the ECU 2 described later. An in-cylinder pressure sensor 10 is integrally attached to the injector 6. The in-cylinder pressure sensor 10 (pressure state detection device) is composed of a piezoelectric element, and outputs a detection signal indicating the amount of change in pressure in the cylinder 3a of the engine 3 to the ECU 2. The ECU 2 calculates a pressure (hereinafter referred to as “in-cylinder pressure”) PCYL (pressure state) in the cylinder 3a based on the detection signal.

  The crankshaft 3 d of the engine 3 is provided with a cylinder discrimination sensor 11 and a crank angle sensor 12. Each of these sensors 11 and 12 includes a magnet rotor and an MRE pickup, and outputs a pulse signal at each predetermined crank angle position. Specifically, the cylinder discrimination sensor 11 generates a cylinder discrimination signal CYL (hereinafter referred to as “CYL signal”) at a predetermined crank angle position of a specific cylinder 3a.

  The crank angle sensor 12 generates a CRK signal and a TDC signal, which are pulse signals, as the crankshaft 3d rotates. The CRK signal is output every predetermined crank angle (for example, 1 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position near the TDC at the start of the intake stroke, and is output at every crank angle of 180 ° in this example of the 4-cylinder type.

  The intake pipe 4 is provided with an intake throttle valve 7 for controlling the intake air amount. The intake throttle valve 7 is connected to an actuator 7a made of, for example, a DC motor. The opening degree of the intake throttle valve 7 is controlled by the ECU 2 controlling the duty ratio of the current supplied to the actuator 7a.

  An intake air temperature sensor 13 and an intake pressure sensor 14 are provided on the intake pipe 4 downstream of the intake throttle valve 7. The intake air temperature sensor 13 detects the temperature of the intake air (hereinafter referred to as “intake air temperature”) TA, the intake pressure sensor 14 detects the intake pressure PBA as an absolute pressure, and these detection signals are output to the ECU 2.

  Further, the ECU 2 receives from the accelerator opening sensor 16 a detection signal indicating the temperature TW (hereinafter referred to as “engine water temperature”) TW of the coolant circulating in the cylinder block (not shown) of the engine 3 from the water temperature sensor 15. , A detection signal representing an operation amount (hereinafter referred to as “accelerator opening degree”) AP of an accelerator pedal (not shown) is output.

In the present embodiment, the ECU 2 is constituted by a microcomputer including an I / O interface, a CPU, a RAM, a ROM, and the like. The detection signals from the various sensors 10 to 16 described above are output to the CPU after A / D conversion and shaping by the I / O interface. In this embodiment, the ECU 2 includes a pressure state detection device, a fuel supply stop unit, a vector calculation unit, a vector deviation calculation unit, an inflection point timing calculation unit, an abnormality determination unit , a top dead center timing detection unit, and a peak timing calculation. Corresponds to means.

  In accordance with these input signals, the CPU determines the operating state of the engine 3 according to a control program stored in the ROM and the like, and executes an abnormality determination process for the in-cylinder pressure sensor 10 according to the determined operating state. This abnormality determination is performed for each cylinder 3a based on the CYL signal. In the following description, the same processing is performed for each cylinder 3a, and therefore, for convenience of description, one cylinder 3a is described.

  2 to 4 are flowcharts showing an abnormality determination process of the in-cylinder pressure sensor 10. This process is executed in synchronization with the generation of the CRK signal. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not an abnormality determination execution condition is satisfied. It is determined that this execution condition is satisfied when the detected engine speed NE, intake air temperature TA, engine water temperature TW, and intake air pressure PBA are all within predetermined ranges. If the determination result is NO and the execution condition is not satisfied, the present process is terminated.

  On the other hand, if the determination result in step 1 is YES and the abnormality determination execution condition is satisfied, it is determined whether or not the fuel is being cut during deceleration of the engine 3 (step 2). When the determination result is NO, the present process is terminated as it is without executing the abnormality determination. On the other hand, if the determination result in step 2 is YES and the fuel cut during deceleration is being performed, it is determined whether or not the current crank angle CA is 180 ° or more and 540 ° or less (step 3).

  The crank angle CA is calculated by the calculation process shown in FIG. This process is also executed in synchronization with the generation of the CRK signal. First, in step 51, it is determined whether or not a TDC signal has been generated. If the determination result is YES and a TDC signal is generated, the crank angle CA is reset to 0 (step 52), and this process is terminated. On the other hand, when the determination result in step 51 is NO, a value obtained by adding 1 to the previous crank angle CA is calculated as the current crank angle CA (step 53), and this process is terminated. As described above, the CRK signal is output every 1 °. For this reason, the crank angle CA calculated as described above in synchronism with the occurrence thereof represents the crank angle based on the TDC position at the time of generation of the TDC signal, that is, at the start of the intake stroke, and 0 at this TDC position. °, 180 ° at the BDC position at the start of the compression stroke, 360 ° at the TDC position at the start of the expansion stroke, and 540 ° at the BDC position at the start of the exhaust stroke (see FIG. 6).

Returning to FIG. 2, when the determination result of step 3 is NO and the crank angle CA is less than 180 ° or larger than 540 °, that is, when the engine 3 is in the intake stroke to the intake stroke, this processing is terminated. On the other hand, when the determination result of step 3 is YES and 180 ° ≦ CA ≦ 540 °, that is, when the engine 3 is in the compression stroke to the expansion stroke, the cylinder pressure PCYL is read from the output of the cylinder pressure sensor 10 (step 4). . Next, a vector θ which is a change state parameter of the in-cylinder pressure PCYL is calculated by the following equation (1) (step 5).
θ = tan ^-1 [(PCYL (n) -PCYL (n-1)) / (CA (n) -CA (n-1))] (1)

As is apparent from this equation (1) and FIG. 7, the vector θ is the difference in the crank angle CA between the current time and the previous time (= CA (n) −CA (n−1) = 1 °), that is, the unit. The inclination (inclination angle) of the hypotenuse of a right triangle with the crank angle as the base and the amount of change in the in-cylinder pressure PCYL (= PCYL (n) -PCYL (n-1)) between them, that is, the previous value of the in-cylinder pressure PCYL Represents the slope of the line segment that connects the current value. Therefore, the sign of the vector θ represents the increase / decrease direction of the in-cylinder pressure PCYL at the unit crank angle, and the absolute value represents the degree of increase / decrease of the in-cylinder pressure PCYL.

  Next, a deviation (= θ (n) −θ (n−1)) between the current value θ (n) and the previous value θ (n−1) of the vector θ is calculated as a vector deviation dθ (step 6). .

  FIG. 6 shows changes in in-cylinder pressure PCYL, vector θ, and vector deviation dθ during fuel cut when the in-cylinder pressure sensor 10 is normal. That is, when 180 ° ≦ crank angle CA ≦ 540 ° (compression stroke to expansion stroke), since both the intake valve 4a and the exhaust valve 5a are closed, the in-cylinder pressure PCYL depends on the position of the piston 3b. And increases from the BDC position at the start of the compression stroke (hereinafter referred to as “first BDC1” below (CA = 180 °)) to the TDC position at the start of the expansion stroke ((CA = 360 °)). This decreases until the BDC position at the start of the exhaust stroke (hereinafter referred to as “second BDC2” ((CA = 540 °) or less)), so that the vector θ becomes a positive value between the first BDC1 and TDC, and TDC to second BDC2 In-cylinder pressure PCYL peaks at the TDC position, and the vector θ becomes zero.

  Further, an inflection point of the in-cylinder pressure PCYL appears between the first BDC1 and the TDC (hereinafter referred to as “first inflection point IP1”), and the increase degree of the in-cylinder pressure PCYL gradually increases to the first inflection point IP1. It becomes larger and gradually becomes smaller after the first inflection point IP1. Therefore, at the first inflection point IP1, the vector θ becomes the maximum value, and the vector deviation dθ becomes zero. On the other hand, an inflection point of the in-cylinder pressure PCYL appears between the TDC and the second BDC2 (hereinafter referred to as “second inflection point IP2”), and the degree of decrease in the in-cylinder pressure PCYL gradually increases to the second inflection point IP2. It becomes larger and gradually becomes smaller after the second inflection point IP2. Therefore, at the second inflection point IP2, the vector θ is the minimum value, and the vector deviation dθ is 0.

Returning to FIG. 2, in step 7 following step 6, the current value θ (n) of the vector θ is larger than 0, the previous value dθ (n−1) of the vector deviation dθ is 0 or more, and the current value dθ. It is determined whether (n) is 0 or less. When the determination result is YES, that is, when the in-cylinder pressure PCYL is increasing and the vector deviation dθ is switched from the positive value to the negative value between the previous time and the current time, the in-cylinder pressure PCYL is the first inflection point. Assuming that the timing has reached IP1, the crank angle CA at that time is set as the first inflection point angle CAIP1 (step 8). Next, a value obtained by subtracting 180 (degrees) from the first inflection point angle CAIP1 is calculated as a first angle section CAbtdc ⁺ (step 9). As is clear from this definition, the first angle section CAbtdc ⁺ corresponds to the crank angle section from the first BDC1 to the first inflection point IP1 (see FIG. 6). Next, by adding the calculated first angle section CAbtdc ⁺ to the first angle section integrated value ΣCAbtdc ⁺ up to the previous time, the current first angle section integrated value ΣCAbtdc ⁺ is obtained (step 10), and this processing is performed. finish.

On the other hand, when the determination result of step 7 is NO, the previous value θ (n−1) of the vector is 0 or more, the current value θ (n) is 0 or less, and the current value dθ (n) of the vector deviation is 0. It is discriminated whether or not it is smaller (step 11). If the determination result is YES, it is determined that the in-cylinder pressure PCYL has reached the peak, and the crank angle CA at that time is set as the peak angle CAPEAK (step 12). Next, a value obtained by subtracting the first inflection point angle CAIP1 from the peak angle CAPEAK is calculated as a second angle section CAbtdc ⁻ (step 13). The second angle section CAbtdc ^- corresponds to the crank angle interval between the first inflection point IP1 to the peak angle CAPEAK (see FIG. 6). Then, the calculated second angle section CAbtdc ^- the previous to the second angular interval integration value ShigumaCAbtdc ^- by adding to, this second angle interval integration value ShigumaCAbtdc ^- the obtaining (step 14).

  Next, the current peak angle integrated value ΣCAPEAK is obtained by adding the peak angle CAPEAK to the previous peak angle integrated value ΣCAPEAK (step 15), and this process is terminated.

On the other hand, when the determination result of step 11 is NO, the current value θ (n) of the vector is smaller than 0, the previous value dθ (n−1) of the vector deviation is 0 or less, and the current value dθ (n). Whether or not is greater than or equal to 0 is determined (step 16). When the determination result is YES, that is, when the in-cylinder pressure PCYL is decreasing and the vector deviation dθ is switched from a negative value to a positive value between the previous time and the current time, the in-cylinder pressure PCYL is the second inflection point. Assuming that the timing has reached IP2, the crank angle CA at that time is set as the second inflection point angle CAIP2 (step 17). Next, a value obtained by subtracting the peak angle CAPEAK from the second inflection point angle CAIP2 is calculated as a third angle section CAatdc ⁻ (step 18). The third angle section CAatdc ⁻ corresponds to a crank angle section between the peak angle CAPEAK and the second inflection point IP2. Then, the calculated third angular section CActdc ^- the previous to the third angle interval integrated value ShigumaCAatdc ^- by adding to, this third angular interval integrated value ShigumaCAatdc ^- the calculated (step 19), the present process finish.

On the other hand, when the determination result in step 16 is NO, it is determined whether or not both the current value θ (n) of the vector and the current value dθ (n) of the vector deviation are substantially 0 (step 20). When the determination result is NO, this process is terminated. On the other hand, when the determination result in step 20 is YES, it is determined that the in-cylinder pressure PCYL has returned to almost zero, and the crank angle CA at that time is set as the zero point return angle CARE (step 21). Next, a value obtained by subtracting the second inflection point angle CAIP2 from the 0-point return angle CARE is calculated as a fourth angle section CAatdc ⁺ (step 22). The fourth angle section CAatdc ⁺ corresponds to a crank angle section between the second inflection point IP2 and the zero point return angle CARE (see FIG. 6). Next, the fourth angle section integrated value ΣCAatdc ⁺ of this time is obtained by adding the calculated fourth angle section CAatdc ⁺ to the previous fourth angle section integrated value ΣCAatdc ⁺ (step 23). Then, the counter value CSCNT of the counter that counts the number of times of calculation such as the first angle interval integrated value ΣCAbtdc ⁺ in the steps 10, 14, 19, and 23 is incremented (step 24).

Next, it is determined whether or not the counter value CSCNT has reached a predetermined value CSJUD (for example, 50) (step 25). When the determination result is NO, this process is terminated. On the other hand, if the determination result in step 25 is YES and the number of calculations reaches a predetermined value CSJUD, the first to fourth angle interval integrated values ΣCAbtdc ⁺ , ΣCAbtdc ⁻ , ΣCAatdc ⁻ , and ΣCAatdc ⁺ calculated so far are predetermined. By dividing each by the value CSJUD, the average values CAbtdc ⁺ avr, CAbtdc ^- avr, CAatdc ^- avr, CAatdc ⁺ avr of the first to fourth angle intervals are calculated (step 26).

Next, reference values CAES1 to CAES4 of the first to fourth angle sections CAbtdc ⁺ , CAbtdc ⁻ , CAatdc ⁻ , and CAatdc ⁺ are calculated (step 27). These reference values CAES1 to CAES4 are calculated, for example, by searching respective predetermined tables (not shown) according to the engine speed NE.

Next, the difference between the first to fourth average values CAbtdc ⁺ avr, CAbtdc ^- avr, CAatdc ^- avr, CAatdc ⁺ avr calculated in step 26 and the corresponding reference values CAES1-CAES4 calculated in step 27 It is determined whether or not each of the absolute values of these is equal to or smaller than a predetermined angle CALMT (for example, 3 ° to 10 °) (step 28).

When this determination result is NO, since at least one of the first to fourth average values CAbtdc ⁺ avr, CAbtdc ^- avr, CAatdc ^- avr, CAatdc ⁺ avr is largely deviated from the reference values CAES1-CAES4, It is determined that the waveform abnormality of the in-cylinder pressure PCYL has occurred, and in order to express this, the waveform abnormality flag F_SHAPENG is set to “1” (step 30). The first to fourth angle interval integrated values ΣCAbtdc ⁺ , ΣCAbtdc ⁻ , ΣCAatdc ⁻ , ΣCAatdc ⁺ , and the peak angle integrated value ΣCAPEAK are all reset to 0 (step 36), and the counter value CSCNT of the counter is set to 0. After resetting (step 37), this process is terminated. If the in-cylinder pressure sensor 10 determines that the waveform is abnormal, a warning lamp (not shown) is turned on, and thereafter, control using the in-cylinder pressure PCYL is prohibited.

  On the other hand, when the determination result in step 28 is YES, it is determined that the waveform of the in-cylinder pressure sensor 10 is normal, the waveform abnormality flag F_SHAPENG is set to “0” (step 29), and then the process proceeds to step 31.

  In step 31, the peak angle average value CAPEAKavr is calculated by dividing the peak angle integrated value ΣCAPEAK calculated in step 15 by the predetermined value CSJUD. Next, a reference value CATDCES for the peak angle CAPEAK is calculated (step 32). The reference value CATDCES is calculated by correcting the output value according to the model of the in-cylinder pressure sensor to be used, for example, based on TDC (= 360 °).

  It is determined whether or not the absolute value (= | CAPEAKAvr−CATDCES |) of the difference between the average value CAPEAKAvr calculated as described above and the reference value CATDCES is equal to or less than a predetermined angle CATDLMMT (for example, 3 ° to 10 °) ( Step 33). When this determination result is NO, the average value CAPEAKavr is greatly deviated from the reference value CATDCES, and it is determined that an offset abnormality in which the phase of the output of the in-cylinder pressure sensor 10 is largely shifted has occurred, and this is indicated. In addition, after the offset abnormality flag F_OFFSETNG is set to “1” (step 35), the process proceeds to step 36 and the subsequent steps, and this process is terminated. When it is determined that the in-cylinder pressure sensor 10 is abnormal in offset, the fuel injection timing may be corrected in accordance with the degree of the phase shift, thereby burning while compensating for the phase shift of the in-cylinder pressure PCYL. The injection timing can be appropriately controlled.

  On the other hand, when the determination result in step 33 is YES, it is determined that no offset abnormality has occurred, and the offset abnormality flag F_OFFSETNG is set to “0” (step 34), and then the process proceeds to step 36 and subsequent steps. Exit.

As described above, according to the present embodiment, the vector θ of the in-cylinder pressure PCYL at the unit crank angle and its vector deviation dθ are continuously calculated based on the in-cylinder pressure PCYL detected during the fuel cut during deceleration. . Further, based on the vector θ and the vector deviation dθ, the first inflection point IP1, the peak angle CAPEAK, the second inflection point IP2, and the zero point return angle CARE are calculated, and the first BDC1 to IP1 to CAPEAK to IP2 are calculated. Average values CAbtdc ⁺ avr, CAbtdc ^- avr, CAatdc ^- avr, and CAatdc ⁺ avr of the first to fourth angle sections that are the respective angle sections of CARE are calculated. Then, it is determined whether or not any of the calculated average values CAbtdc ⁺ avr, CAbtdc ⁻ avr, CAatdc ⁻ avr, CAatdc ⁺ avr and the absolute value of the deviation between the reference values CAES1 to CAES4 is equal to or smaller than the predetermined angle CALMT. By doing (step 28), the waveform abnormality of the in-cylinder pressure sensor 10 is determined.

When the waveform has an abnormal disturbance as shown in FIG. 7A, the generation timing of the first or second inflection point IP1, IP2 is shifted, and the first to fourth angle sections CAbtdc ⁺ , CAbtdc ⁻ , Since at least one of CAatdc ⁻ and CAatdc ⁺ deviates greatly from the corresponding reference values CAES1 to CAES4, it is possible to appropriately determine that a waveform abnormality has occurred when the determination result in step 28 is NO. it can. Further, even when the gain change or drift occurs and the value of the in-cylinder pressure PCYL itself fluctuates, the first and second inflection points IP1 and IP2 are generated as long as the waveform changes normally. Since the timing does not change, it is possible to appropriately determine that the in-cylinder pressure sensor 10 is normal when the determination result in step 28 is YES.

  As described above, the first and second inflection points IP1 and IP2 are obtained based on the vector θ and the vector deviation dθ, and abnormality determination is performed based on the first and second inflection points IP1 and IP2, and therefore, the peak angle CAPEAK and the peak angle CAPEAK of the in-cylinder pressure PCYL are determined. It is possible to appropriately determine the waveform abnormality while quantitatively grasping the state of transition from.

  Further, by comparing the peak angle CAPEAK calculated based on the vector θ and the vector deviation dθ with the reference value CATDCES calculated based on the TDC timing, it is possible to appropriately determine the offset abnormality of the in-cylinder pressure sensor 10. .

Further, since the average values CAbtdc ⁺ avr, CAbtdc ^- avr, CAatdc ^- avr, CAatdc ⁺ avr of a predetermined number of times are used as the first to fourth angle sections to be compared with the reference values CAES1 to CAES4, the in-cylinder pressure sensor 10 is normal. In some cases, even when the generation timing of the first or second inflection point IP1 or IP2 is temporarily shifted, it is possible to reliably avoid erroneously determining that the waveform is abnormal while eliminating the influence. The reliability of determination can be improved. The same applies to the determination of the offset abnormality.

In addition, this invention can be implemented in a various aspect, without being limited to embodiment described. For example, in the embodiment, the vector θ is used as the change state parameter of the in-cylinder pressure PCYL. However, the present invention is not limited to this. For example, a deviation between the current value and the previous value of the in-cylinder pressure PCYL may be used. In the embodiment, the average value CAbtdc ⁺ avr of the first angle section for determining the waveform abnormality of the in-cylinder pressure sensor 10 is compared with the reference value CAES1, etc. using the deviation between the two. For example, the ratio between the two may be used. The same applies to the comparison between the average value CAPEAKavr of the peak angle and the reference value CATDCES when determining the offset abnormality. Furthermore, in the embodiment, four angle sections including the first angle section CAbtdc ⁺ are used as parameters representing the inflection point timing. However, the first and second inflections calculated in Step 8 and Step 17 are used. Point angles CAIP1 and CAIP2 may be used. In this case, these values are compared with predetermined crank angles corresponding to the first and second inflection points.

Further, the calculation interval (= 1 °) of the vector θ and the number of integrations (= 50) such as the first angle section CAbtdc ^{+ in the} embodiment are merely examples, and can be arbitrarily changed.

  Furthermore, although embodiment is an example which applied this invention to the diesel engine, this invention is not limited to this, Various engines other than a diesel engine, for example, the ship which arrange | positioned the gasoline engine and the crankshaft in the perpendicular direction It can be applied to an engine for a marine propulsion device such as an external unit. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 is a diagram illustrating a schematic configuration of an abnormality determination device of the present invention and an internal combustion engine to which the abnormality determination device is applied. It is a flowchart which shows a part of main flow of the abnormality determination process of a cylinder pressure sensor. It is a flowchart which shows the remainder of FIG. It is a flowchart which shows the remainder of FIG. It is a flowchart of the calculation process of a crank angle. It is a figure which shows transition of a cylinder pressure, a vector, and a vector deviation when a cylinder pressure sensor is normal. (A) It is a figure for demonstrating the definition of vector (theta) while showing an example of the waveform of a cylinder pressure sensor, and expanding and showing the arrow A part of (b) and (a).

Explanation of symbols

1 Abnormality judgment device
2 ECU (pressure-state detecting device, a fuel supply stopping means, vector calculating means, base
Couttle deviation calculating means, inflection point timing calculating means, abnormality determining means , top dead
Point timing detection means and peak timing calculation means)
3 Engine
3a cylinder
3b piston
6 Injector (fuel supply stop means)
10 In-cylinder pressure sensor (pressure state detection device)
IP1 1st inflection point IP2 2nd inflection point PCYL In-cylinder pressure (pressure state)
θ vector
dθ vector deviation
The current value of θ (n) vector
θ (n−1) vector previous value CATDCES reference value (top dead center timing)

Claims (2)

An abnormality determination device for a pressure state detection device for detecting a pressure state in a cylinder of an internal combustion engine,
Fuel supply stop means for stopping the supply of fuel to the internal combustion engine during operation of the internal combustion engine;
Based on the pressure state detected when the fuel supply to the internal combustion engine is stopped by the fuel supply stop means, the increasing / decreasing direction and the increasing / decreasing degree of the pressure state between the compression stroke and the expansion stroke are respectively determined. Vector calculating means for continuously calculating a plurality of vectors to be represented;
A vector deviation calculating means for continuously calculating a plurality of vector deviations representing a difference between the current value and the previous value of the calculated vectors;
On the basis of transition of a plurality of vectors and vector deviation the calculated, and the detected pressure states first and second inflection point timing calculating means for calculating the timing of reaching the inflection point,
An abnormality determination means for determining a waveform abnormality of the pressure state detection device by comparing the calculated first and second inflection point timings with predetermined first and second timings, respectively ;
An abnormality determination device for a pressure state detection device, comprising: A top dead center timing detection means for detecting a top dead center timing at which the piston of the internal combustion engine has reached top dead center;
The abnormality determining means includes
Peak timing calculation means for calculating a peak timing at which a peak of the detected pressure state occurs based on the transition of the vector and the vector deviation ,
2. The abnormality of the pressure state detection device according to claim 1 , wherein an offset abnormality of the pressure state detection device is determined by comparing the detected top dead center timing with the calculated peak timing. Judgment device.

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