JP2007107506A - Maximum cylinder pressure information detection device for engine and ignition timing control device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a maximum cylinder pressure crank angle detection device capable of detecting timing at which cylinder pressure gets maximum with reducing load on a control system while keeping cost low. <P>SOLUTION: In detection of timing at which cylinder pressure in a cylinder 2 of the engine 1 gets the maximum, cylinder pressure information S from the cylinder pressure detection means 4 detecting pressure in a cylinder is differentiated, timing at which differentiation output crosses zero is detected, number of crank angle pulses in a section L from output of pulse signal SGT output at reference crank angle and detection of zero cross, and crank angle θPmax which is maximum cylinder pressure timing is calculated by a cylinder pressure information process circuit 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to information relating to a state in which the in-cylinder pressure of the engine becomes maximum, and more particularly, to a crank angle detection device that maximizes the in-cylinder pressure of the engine and an ignition timing control device using the same.

  In general, considering the engine efficiency of the engine, it is said that it is better to ignite in the vicinity of the so-called MBT (Minimum Advance For Best Torque), the crank angle at which a good torque can be obtained with the minimum advance angle. MBT control for changing the ignition timing has already been performed. That is, when the ignition timing is optimal (MBT) and the engine torque is maximum, the maximum in-cylinder pressure is known to be a predetermined crank angle (15 ° ATDC). The ignition timing may be controlled so that the in-cylinder pressure becomes maximum at (15 ° ATDC).

  In order to perform this control, it is necessary to detect the pressure in the cylinder. Therefore, the cylinder pressure is detected using an in-cylinder pressure sensor, and the ignition timing is controlled according to the detection result. For example, in Patent Document 1, in order to increase the detection accuracy of the in-cylinder pressure by the in-cylinder pressure sensor, a program is run every 2 ° of crank angle to calculate the crank angle θPmax at which the in-cylinder pressure is maximum, and the calculated crank angle is It is described that the ignition timing is controlled to coincide with a predetermined target crank angle.

JP-A 63-246445

However, in Patent Document 1, the crank angle θPmax at which the in-cylinder pressure is maximized is calculated while the in-cylinder pressure information is processed by running the program every 2 ° of the crank angle, so that the calculation load on the control system is extremely high. In order to further improve the detection accuracy, it is necessary to further reduce the crank angle interval for taking in-cylinder pressure information, and the calculation load on the control system is further increased. For this reason, if it is going to suppress the calculation load to a control system, the crank angle space | interval which takes in cylinder pressure information must be enlarged, and there exists a problem that a detection system falls this time.
The present invention provides an engine maximum in-cylinder pressure information detecting device capable of detecting a crank angle at which in-cylinder pressure is maximized by reducing calculation addition to a control system while suppressing cost, and an ignition timing device using the same. That is the purpose.

  In order to achieve the above object, an engine maximum in-cylinder pressure information detecting device according to the present invention includes an in-cylinder pressure detecting means for detecting a pressure in a cylinder of the engine, and a differentiation circuit for differentiating in-cylinder pressure information from the in-cylinder pressure detecting means. A zero-cross detection circuit that detects the timing at which the differential output from the differentiation circuit crosses zero, a reference timing sensor that detects the timing at which the reference crank angle near the compression top dead center of the engine is reached, and a pulse signal at predetermined crank angle intervals Angle sensor, a logic gate circuit that measures the interval from when the reference timing sensor detects the reference timing until the zero cross detection circuit detects zero cross, and a crank angle sensor in the interval detected by the logic gate circuit Counter circuit for counting the number of pulses of the reference crank angle and the counter circuit Cylinder pressure in the cylinder of the engine based on the force is characterized by detecting a crank angle of maximum.

The maximum in-cylinder pressure information detecting device for an engine according to the present invention is characterized by further having a peak hold circuit for peak-holding the in-cylinder pressure information from the in-cylinder pressure detecting means to detect the maximum in-cylinder pressure.
In the maximum in-cylinder pressure information detecting apparatus for an engine according to the present invention, the engine is multi-cylinder, further includes a multiplexer for synthesizing in-cylinder pressure information from the in-cylinder pressure detecting means of the angular cylinder, and the peak hold circuit is an output from the multiplexer. In response, the maximum in-cylinder pressure of each cylinder is sequentially detected.

  An apparatus for controlling the ignition timing of an ignition means provided in an engine according to the present invention, wherein the basic ignition timing is determined in accordance with a crank angle at which the maximum in-cylinder pressure is detected by any one of the maximum in-cylinder pressure information detecting devices. Is controlled to advance or retard.

  According to the present invention, the differential output of the in-cylinder pressure information is zero-crossed from the reference crank angle near the compression top dead center of the engine by organically combining the differential circuit, the zero cross detection circuit, the logic gate circuit, and the counter circuit. The crank angle at which the in-cylinder pressure is maximized is calculated based on the number of pulses of the crank angle sensor in the section and the reference crank angle, eliminating the need for special software and large-capacity calculation control processing capability, while reducing costs It is possible to reduce the load on the control system and detect the crank angle at the maximum in-cylinder pressure.

  According to the present invention, the basic ignition timing is advanced or retarded in accordance with the crank angle that is the maximum in-cylinder pressure detected by the maximum in-cylinder pressure information detecting device of the engine, so that the engine torque can be obtained efficiently. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The overall configuration will be described with reference to FIG. A spark plug 3 and an in-cylinder pressure sensor 4 as in-cylinder pressure detecting means are mounted on the upper portion of the cylinder 2 of the engine indicated by reference numeral 1 in FIG. 1 so as to face the combustion chamber 5. In the present embodiment, the in-cylinder pressure sensor 4 is disposed in the vicinity of the intake valve 6. The in-cylinder pressure sensor 4 converts the combustion pressure in the cylinder into charges by a piezoelectric element, and outputs a charge output S to the charge amplifier 7. The charge amplifier 7 is a so-called charge-voltage conversion amplifier, converts the charge output S into a signal, and outputs the signal to the in-cylinder pressure information processing circuit 30 configured by an electric circuit. As will be described later, the in-cylinder pressure information processing circuit 30 calculates the maximum in-cylinder pressure and the crank angle at which the maximum in-cylinder pressure is obtained, and outputs it to an engine control unit (hereinafter referred to as “ECU”) 10 serving as control means. The voltage signal S is pressure information detected by the in-cylinder pressure sensor 4.

  The ECU 10 is a known computer including a CPU 21, a ROM 22, a RAM 23, and an I / O port 24, which are connected to each other by a common bus 25. The ECU 10 includes a timer (not shown) for measurement. The CPU 11 fetches necessary external data from the I / O port 24 in accordance with a program written in the ROM 12 in advance, and calculates necessary processing values and the like while exchanging data with the RAM 23. In response, the processed data is output to the I / O port 24. The I / O port 24 receives signals from various sensors such as the intake air flow rate Qa detected by the airflow sensor 11 and the crank angle signal Ca of the engine 1 detected by the crank angle sensor 12. From the I / O port 24, the ignition signal Sp is output to the ignition plug 3, and the injection signal Si is output to the injector 14 for fuel injection. The ROM 22 stores basic ignition timing and basic fuel injection amount data (not shown) from the engine speed Ne and the intake air flow rate Qa serving as load information. That is, the ECU 10 has a function of performing ignition timing and fuel supply control based on the input sensor information.

  An in-cylinder pressure information processing circuit 30 is connected to the ECU 10 via an I / O port 24. The in-cylinder pressure information processing circuit 30 calculates the maximum in-cylinder pressure (Pmax) in the combustion chamber 5 and the crank angle (θPmax) that is the maximum in-cylinder pressure. In-cylinder pressure information processing circuit 30 includes pressure information S (voltage signal S) detected by pressure detection sensor 4, reference timing signal SGT detected by reference timing sensor 8, and engine detected by crank angle sensor 12. 1 crank angle signal Ca and a reset signal are input. In this embodiment, the injection signal Si output from the ECU 10 is used as the reset signal.

  Reference timing sensor 8 From the [H] level at a predetermined position before compression top dead center (TDC) of each cylinder at every explosion interval (crank angle is 120 degrees for a 6-cylinder engine and 180 degrees for a 4-cylinder engine), for example, BTDC 5 ° [L] A reference timing signal SGT that is a pulse falling to the level is output. The crank angle sensor 12 outputs a unit signal Ca that becomes a pulse of (H) level for every unit angle (for example, 1 °) of the crank angle. Note that the engine speed Ne can be known by counting the pulses of the unit signal Ca, and this process is performed by the ECU 10.

The in-cylinder pressure information processing circuit 30 includes a peak hold circuit 31, a differentiation circuit 32, a zero point detection circuit 33, a logic gate 34, and a counter circuit 35, as shown in FIGS. The peak hold circuit 31 holds the pressure information S until the reset signal is input by inputting the pressure information S in the cylinder detected by the in-cylinder pressure detection sensor 4 and the injection signal Si as a reset signal. When the maximum in-cylinder pressure (Pmax) is detected and a reset signal is input, the held value is reset. The differentiating circuit 32 receives the pressure information (in-cylinder pressure signal) S detected by the in-cylinder pressure detection sensor 4 and differentiates the in-cylinder pressure signal. The zero point detection circuit 33 receives the differential output from the differentiation circuit 32, and detects the zero cross timing at which the differential output becomes zero. The logic gate 34 receives the SGT signal, the zero cross timing signal, and the crank angle signal Ca, and extracts only the section L indicated by hatching in FIG. In this embodiment, the logic gate 34 is composed of a NOR circuit as shown in FIG. The counter circuit 35 receives the crank angle signal Ca and the reset signal in the section L signal extracted by the logic gate 34, and counts the crank angle signal Ca by the section L. That is, only the number of pulses of the crank angle signal Ca from the reference crank angle (BTDC 5 °) to the maximum in-cylinder pressure (Pmax) is counted, and when the reset signal is input, the count is reset.
Thus, the crank angle difference between the reference crank angle and the crank angle at which the maximum in-cylinder pressure is reached can be calculated, and the crank angle at which the maximum in-cylinder pressure is reached is calculated based on this angle difference and the reference crank angle. be able to.

  Next, the basic principle of ignition timing control using maximum in-cylinder pressure information will be described. The ECU 10 calculates the ignition timing and the fuel injection amount based on the intake air flow rate Qa and the engine speed Ne. At this time, the timing (crank angle θPmax) at which the in-cylinder pressure becomes the maximum in-cylinder pressure (Pmax) is a predetermined target. MBT can be achieved by adjusting the ignition timing so as to coincide with the value θ1 (15 ° ATDC).

  That is, when the engine 1 is started, signals from the air flow sensor 11, the crank angle sensor 12, and the in-cylinder pressure detection sensor 4 are fetched, and the engine speed Ne is obtained from the crank angle signal Ca. Then, the ECU 10 calculates the basic ignition timing from the intake air flow rate Qa and the engine speed Ne. The pressure information S from the in-cylinder pressure detection sensor 4 is input to the peak hold circuit 31 and the differentiation circuit 32. The peak hold circuit 31 detects the maximum in-cylinder pressure (Pmax), the differentiation circuit 32 differentiates it, and the zero point is detected. The circuit 33 detects the zero cross timing regarded as the maximum in-cylinder pressure timing. Then, the logic gate 34 extracts only the section L (see FIG. 4) from the fall of the SGT signal, which is the reference crank angle timing, to the zero cross timing, and the counter circuit 35 counts the crank angle signal Ca every one degree. Thus, the crank angle (θPmax) that is the maximum in-cylinder pressure timing is calculated.

  The calculated maximum in-cylinder pressure (Pmax) and the crank angle (θPmax) serving as the maximum in-cylinder pressure timing are input to the ECU 10. The ECU 10 compares a predetermined target value θ1 after compression top dead center stored in advance in the ROM 22 with θPmax. In this embodiment, the target value θ1 is 15 ° ATDC. When the target value θ1 = θPmax, the ignition signal Sp is output so that a spark is emitted from the spark plug 3 without correcting the basic ignition timing because the ignition timing is MBT.

  On the other hand, if the condition of target value θ1 = θPmax is not satisfied, the difference between target value θ1 and θPmax is determined. When θPmax is retarded from the target value θ1, the basic ignition timing is advanced, and an ignition signal Sp is output so that a spark is emitted from the spark plug 3 at the advanced angle. If the target value θ1 <θPmax is not satisfied, that is, if θPmax is advanced from the target value θ1, the basic ignition timing is retarded, and an ignition signal is emitted so that sparks fly from the spark plug 3 at the retarded timing. Sp is output.

  In this way, the in-cylinder pressure information S detected by the in-cylinder pressure detection sensor 3 is differentiated to detect the timing at which the differential output zero-crosses, and the output of the pulse signal (SGT) output at 5 degrees before compression top dead center Since the crank angle (θPmax) that is the maximum in-cylinder pressure timing is calculated by measuring the number of pulses of the crank signal in the section L from when the zero cross pulse is detected, special software and large capacity calculation control processing capability This eliminates the need for high cost, and it is possible to detect the timing when the maximum in-cylinder pressure is reached by reducing the load on the control system while reducing the cost.

  5 and 6 show another embodiment of the present invention. In this embodiment, an in-cylinder pressure information processing circuit 40 is connected to the ECU 10. Since the in-cylinder pressure information processing circuit 40 has basically the same configuration as the in-cylinder pressure information processing circuit 30, only the differences will be described. The in-cylinder pressure information processing circuit 40 is characterized in that it includes a multiplexer 50 and a logic gate 51. That is, in this embodiment, the in-cylinder pressure signal (pressure information S) output from the in-cylinder pressure detection sensor 3 provided in each cylinder 2 and the extraction signal corresponding to each cylinder are input to the multiplexer 50, and from any cylinder. A period during which the in-cylinder pressure signal (pressure information S) does not enter is provided. An extraction signal is also input to the logic gate 51, and a period during which this in-cylinder pressure signal (pressure information S) does not enter is extracted and used as a reset signal for each cylinder. The multiplexer 50 combines the input in-cylinder pressure signal (pressure information S) and inputs it to the peak hold circuit 31. The synthesized in-cylinder pressure signal (pressure information S) is also input to the differentiating circuit 32.

  In the ignition control circuit 40 having such a configuration, the ECU 10 calculates the basic ignition timing from the intake air flow rate Qa and the engine speed Ne, and pressure information S from the in-cylinder pressure detection sensor 4 of each cylinder passes through the multiplexer 50. The peak hold circuit 31 and the differentiation circuit 32 are input as combined values, the peak hold circuit 31 detects the maximum in-cylinder pressure (Pmax) of each cylinder, and the differentiation circuit 32 differentiates each cylinder value. The zero point detection circuit 33 detects the zero cross position of each cylinder regarded as the maximum in-cylinder pressure. Then, using the logic gate 34, only the section L1 (hatched area in FIG. 6) from the falling edge of the SGT signal, which is a pulse signal output at 5 degrees before compression top dead center, to the zero cross position is extracted, and the counter circuit 35 Thus, by counting the crank angle signal Ca every one degree, it is possible to calculate the crank angle (θPmax) as the maximum in-cylinder pressure timing of each cylinder.

  When receiving in-cylinder pressure signals (pressure information S) from a plurality of cylinders in this way, by providing the multiplexer 50, the maximum in-cylinder pressure (Pmax) of each cylinder is shared while sharing a circuit downstream from the peak hold circuit and the differentiation circuit. In addition, the crank angle (θPmax) that is the maximum in-cylinder pressure timing of each cylinder can be accurately detected, and the cost can be more effectively suppressed.

1 is a configuration diagram of an engine system for realizing an engine maximum in-cylinder pressure information detection device and an ignition timing control device using the same according to an embodiment of the present invention. It is a conceptual diagram explaining the logic which detects the crank angle used as the maximum in-cylinder pressure of a cylinder and the maximum in-cylinder pressure timing by this invention. It is a block diagram which shows one structural example of an ignition control circuit. FIG. 4 is a timing chart showing a concept of control for detecting a maximum in-cylinder pressure and a crank angle as a maximum in-cylinder pressure timing by the in-cylinder pressure information processing circuit shown in FIG. 3. It is a block diagram which shows another structural example of an in-cylinder pressure information processing circuit. 6 is a timing chart showing a concept of control for detecting a maximum in-cylinder pressure and a crank angle as a maximum in-cylinder pressure timing by the in-cylinder pressure information processing circuit shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 In-cylinder 4 In-cylinder pressure detection means S In-cylinder pressure information 30, 40 In-cylinder pressure information processing circuit 31 Peak hold circuit 50 Multiplexer L, L1 Section Pmax Maximum in-cylinder pressure θPmax Crank angle that becomes the maximum in-cylinder pressure timing

Claims (4)

In-cylinder pressure detecting means for detecting the pressure in the cylinder of the engine;
A differentiating circuit for differentiating in-cylinder pressure information from the in-cylinder pressure detecting means;
A zero-cross detection circuit that detects the timing at which the differential output from the differentiation circuit zero-crosses;
A reference timing sensor for detecting a timing at which a reference crank angle near the compression top dead center of the engine is reached;
A crank angle sensor that outputs a pulse signal at predetermined crank angle intervals;
A logic gate circuit for measuring a period from when the reference timing sensor detects the reference timing to when the zero cross detection circuit detects the zero cross;
A counter circuit that counts the number of pulses of the crank angle sensor in a section detected by the logic gate circuit;
An engine maximum in-cylinder pressure information detecting device for detecting a crank angle at which an in-cylinder pressure in an engine cylinder is maximum based on the reference crank angle and an output of the counter circuit. The maximum in-cylinder pressure information detecting device for an engine according to claim 1,
A maximum in-cylinder pressure information detecting apparatus for an engine, further comprising a peak hold circuit for peak-holding in-cylinder pressure information from the in-cylinder pressure detecting means to detect a maximum in-cylinder pressure. The maximum in-cylinder pressure information detecting device for an engine according to claim 2,
The engine is multi-cylinder and further includes a multiplexer that synthesizes in-cylinder pressure information from the in-cylinder in-cylinder pressure detecting means, and the peak hold circuit receives the output from the multiplexer and sequentially increases the maximum in-cylinder pressure of each cylinder. A maximum in-cylinder pressure information detecting device for an engine characterized by detecting. An apparatus for controlling the ignition timing of ignition means provided in an engine,
An ignition timing control, wherein the basic ignition timing is advanced or retarded in accordance with a crank angle that is a maximum in-cylinder pressure detected by the maximum in-cylinder pressure information detecting device according to any one of claims 1 to 3. apparatus.

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