JP6284018B2 - Combustion pressure sensor - Google Patents

Description

The present invention relates to a combustion pressure sensor capable of calculating a combustion starting point by measuring a pressure in a combustion chamber of an internal combustion engine.

In general, an engine combustion pressure sensor that detects the pressure of a cylinder by inserting it into a combustion chamber of the engine is known, but this kind of combustion pressure sensor is highly airtight in a through hole formed at a predetermined position of a cylinder. It needs to be installed independently depending on the structure. For this reason, the combustion pressure sensor is configured in a ring shape and can be integrally attached to the outer peripheral surface of the tip of the spark plug, which is another functional part attached to the engine, and can be attached to the cylinder together with the spark plug. Such a cylinder combustion pressure sensor is also known.

Conventionally, as a combustion pressure sensor configured in such a ring shape, a spark plug with a built-in pressure sensor disclosed in Patent Document 1 is known. Patent Document 2 discloses a combustion pressure sensor in which a pressure detection element is divided into pressure receiving ring blocks to prevent cracking due to vibration.

The spark plug with a built-in pressure sensor of Patent Document 1 is built in a seat portion facing the plug mounting surface provided in the internal combustion engine when mounted on the internal combustion engine, and is mounted on the inner wall surface of the seat portion. A housing member in which a plurality of piezoelectric elements are held at predetermined intervals in the circumferential direction and a flat plate corresponding to the housing member are formed, and a terminal is formed by bending a cut portion upward. An electrode plate provided on the upper surface of the housing member in a state where the notch formed by the bending does not overlap the piezoelectric element, and a notch is formed in a flat plate shape corresponding to the electrode plate. It is formed and connected to the insulating plate provided on the upper surface of the electrode plate with the terminal of the electrode plate protruding upward from the notch and the terminal protruding from the notch of the insulating plate. And a, and the lead member for taking out the output of the piezoelectric element.

Patent Document 2 discloses a housing unit formed of an outer cylinder part and an inner cylinder part in which an elastic part having axial elasticity is formed in an intermediate part in the sensor casing axial direction, and an outer cylinder positioned in front of the elastic part. A pressure-receiving ring block portion whose front surface is a pressure-receiving surface, and one of the pressure-receiving ring block portions provided on the rear surface of the pressure-receiving ring block portion. The combustion pressure is applied from the pressure receiving ring block portion in contact with the electrode portion, and is fixed between at least one pressure detection element disposed at a predetermined position in the circumferential direction, and the outer cylinder portion and the inner cylinder portion, and A sensor is disclosed in which the front surface is a support surface that supports the pressure detection element, and a support ring block portion that also serves as the other electrode.

JP 2000-277233 A WO2012 / 132450 publication

Conventional gasoline engine SI (Spark Ignition), diesel engine CI (Compression Ignition), and HCCI (Homogenous Charge Compression Ignition), which is considered to be the next generation engine, are cylinders during combustion. The combustion state inside is not always stable, and the combustion starting point that is the point of variation is not constant, and it is constantly changing according to the mixed gas state and air flow state at each cycle. It is known by taking pictures during combustion with a camera.

In the case of the gasoline engine SI, the spatial position of the combustion starting point varies depending on the relative position between the plug gap center of the spark plug and the mixed gas concentration in the vicinity thereof, the moving speed of the mixed gas, and the like. Therefore, the fluctuation of the spatial position of the combustion starting point depends on the fuel injection conditions of the injector, the timing and lift amount of the intake / exhaust valve, and the engine speed. The position does not fluctuate randomly, but fluctuates with a certain period. As a result, the fluctuation of the in-cylinder pressure does not fluctuate up and down randomly every cycle, but fluctuates with a certain long period.

In the case of the diesel engine CI, the spatial position of the combustion starting point varies depending on the mixed gas concentration of the fuel injected from the injector and air and the moving speed of the mixed gas. Therefore, the variation in the spatial position of the combustion starting point depends on the fuel injection conditions of the injector, the timing and lift amount of the intake and exhaust valves, and the engine speed. Also, it does not fluctuate randomly but fluctuates with a certain period. As a result, the fluctuation of the in-cylinder pressure does not rise and fall randomly every cycle, but fluctuates with a certain long period.

In the case of HCCI, the spatial position of the combustion starting point varies depending on the mixed gas concentration of the injected fuel and air from the injector, the uniformity of the gas concentration, and the moving speed of the mixed gas. Therefore, the variation in the spatial position of the combustion starting point depends on the fuel injection conditions of the injector, the timing and lift amount of the intake and exhaust valves, and the engine speed. Also, it does not fluctuate randomly but fluctuates with a certain period. As a result, the fluctuation of the in-cylinder pressure does not fluctuate up and down randomly every cycle, but fluctuates with a certain long period.

In particular, the CI engine is ignited by an increase in pressure and temperature, so the fluctuation range is large in principle. Originally, the state where the combustion starting point is always on the central axis in the piston moving direction of the combustion chamber is the ideal state. However, as described above, the condition of the mixed gas depends on the conditions of combustion injection, that is, injection amount, injection time, timing, injection length, injection direction, nozzle shape and injection pressure, intake / exhaust valve timing, and valve opening / closing amount. Due to the fluctuation of the air flow, a large amount of fuel injected from the injector adheres to the inner surface of the cylinder, or a large amount adheres to the upper surface of the piston, thereby inhibiting the atomization of the fuel. Therefore, the combustion state in the cylinder is uneven and unstable, abnormal combustion occurs frequently, and many unburned components such as carbon monoxide, hydrocarbons, and soot are discharged. I will do. Also, the combustion efficiency is significantly reduced.

In addition, the HCCI engine has a low-temperature combustion mode compared to the combustion of a normal gasoline engine, so it generates almost no NOx and has the maximum thermal efficiency potential of the internal combustion engine. Although it is expected as a generation engine, a stable combustion region is limited, and it is a big problem to expand this region by optimizing the above-mentioned injection parameters and intake / exhaust valve parameters.

In addition, in order to improve the combustion efficiency of injectors, technological innovations such as dual injection systems are advancing today. In order to make full use of these new functions, the combustion state in the cylinder is ascertained, It is very important to detect the spatial position and feed back to the injector injection amount, injection time, timing, injection length, injection direction, injection pressure, intake / exhaust valve timing, and valve opening / closing amount.

Conventional combustion pressure sensors for engines cannot grasp the combustion state, particularly the combustion starting point, and based on the data, optimize the above-mentioned injection parameters and intake / exhaust valve parameters to determine the combustion state. It was not possible to improve, and the above-mentioned combustion problem could not be solved.

The present invention has been made in view of the above, and an object of the present invention is to propose a combustion pressure sensor capable of calculating a combustion starting point in a cylinder of an engine.

In order to solve the above-described problems and achieve the object, the present invention provides at least three or more sensor elements that are arranged at predetermined positions in the circumferential direction with respect to the central axis and each measure the combustion pressure in the cylinder. And an arithmetic circuit for calculating combustion starting point information in the cylinder based on a reference time and a time of a pressure peak output from the three or more sensor elements.

The sensor elements are arranged at predetermined positions in the circumferential direction with respect to the central axis, and at least three sensor elements that measure the combustion pressure in the cylinder are arranged. Combustion start point information can be calculated.
Information on where combustion occurs from the cylinder by providing an arithmetic circuit for calculating combustion start point information in the cylinder based on a reference time and a time of a pressure peak output from the three or more sensor elements Can be obtained.

As a desirable mode of the present invention, it is preferable that the three or more sensor elements are arranged in a fan shape.

If these three or more sensor elements are arranged in a fan shape, when the injector is arranged in the center, not only can the output of the sensor element be maximized, but also the sensor element pressure sensitive area is the central axis. Therefore, a sharp output peak can be obtained due to pressure fluctuation at the combustion starting point in the vicinity of the central axis.

Furthermore, in the present invention, it is preferable that three or more sensor elements are arranged in a ring shape in the circumferential direction with respect to the central axis, and a plurality of sensor elements are arranged in the radial direction.

When three or more sensor elements are arranged in a ring shape in the circumferential direction with respect to the central axis, and a plurality of radial sensor elements are arranged in the radial direction, the position information of the combustion starting point near the central axis can be calculated with higher accuracy.

Furthermore, in the present invention, the reference time is preferably the time when the crank angle coincides with the reference angle.

By setting the reference time as the time when the crank angle coincides with the reference angle, the reference time is initialized for each cycle, so that accurate and stable combustion starting point information can be obtained.

Further, in the present invention, the time of the pressure peak and the combustion starting point information are accumulated in a data storage unit, and the fluctuation of the long-period combustion starting point is calculated based on the accumulated time and the combustion starting point information.
By accumulating the pressure peak time and the combustion starting point information, it is possible to grasp long-term pressure peak time fluctuations and combustion starting point fluctuations, and to specify the combustion starting point fluctuation factors. As a result, an injector signal can be output so that the combustion starting point is close to the central axis.

Further, in the present invention, the arithmetic circuit calculates a combustion start direction in a plane normal to the central axis based on the reference time and the time of the pressure peak output from the three or more sensor elements. And the data which shows the said combustion starting point direction as said combustion starting point information are output, It is characterized by the above-mentioned.

This makes it possible to quickly obtain appropriate combustion start direction data, and by controlling the fuel injection so that the combustion start point approaches the central axis based on this combustion start direction data, it is possible to maintain good engine combustion faster. Is obtained.

Further, in the present invention, the arithmetic circuit obtains a flame propagation distance based on the reference time, a time of a pressure peak output from the three or more sensor elements, and a flame propagation speed, and determines the flame propagation distance. Based on this, a combustion start position in the cylinder is calculated, and data indicating the combustion start position is output as the combustion start information.

As a result, if the fuel injection is controlled so that the combustion starting point is brought closer to the central axis on the basis of the more accurate combustion starting point position data, an effect of maintaining good engine combustion can be obtained.

Further, the three or more sensor elements are disposed at rotationally symmetric positions with respect to the central axis.

Since the three or more sensor elements are arranged at rotationally symmetric positions with respect to the central axis, the number of sensor elements is arranged at an equal distance from the central axis, so that the calculation of the combustion start point is easy. Thus, the combustion starting point information can be calculated with higher accuracy.

According to the present invention, a combustion pressure sensor capable of calculating combustion starting point information in an engine cylinder is obtained.

FIG. 1 is a schematic perspective view when a combustion pressure sensor according to the best mode of the present invention is applied to an injector. FIG. 2 is a perspective view of the detection part of the combustion pressure sensor of the present invention. FIG. 3 is a schematic diagram of an enlarged cross section of the element portion of the combustion pressure sensor of the present invention. FIG. 4 is a diagram of an arrangement example 1 of a plurality of sensor elements. FIG. 5 is a diagram of an arrangement example 2 of a plurality of sensor elements. FIG. 6 is a diagram of an arrangement example 3 of a plurality of sensor elements. FIG. 7 is a diagram of an arrangement example 4 of a plurality of sensor elements. FIG. 8 is a schematic diagram of in-cylinder combustion. FIG. 9 is a diagram showing the time change of pressure by three different sensor elements. FIG. 10 is a diagram showing an example of a method for calculating a combustion start point in a plane. FIG. 11 is a perspective view showing an example of a combustion starting point calculation method. FIG. 12 is a block diagram showing the configuration of the combustion pressure sensor according to the present embodiment.

Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings. First, the configuration of the combustion pressure sensor 2 according to the present embodiment will be described with reference to FIGS.

FIG. 1 is a schematic perspective view when a combustion pressure sensor 2 according to the best mode is applied to an injector 1. A combustion pressure sensor 2 is installed at the tip of the injector 1 and inserted into the cylinder to detect the combustion pressure. FIG. 2 is a perspective view of a detection part of the combustion pressure sensor.

FIG. 3 is a schematic diagram of an enlarged cross section of the element portion of the combustion pressure sensor. An electrode 21 as a lower electrode is formed on the back surface of the pressure receiving surface of the diaphragm 6 that is directly exposed to the in-cylinder combustion gas, a piezoelectric thin film 22 is formed thereon, and an electrode 23 as an upper electrode is further formed thereon. The The piezoelectric thin film 22 and the electrode 21 or the electrode 23 are repeatedly formed, and a plurality of sensor elements 24 each made of a laminated piezoelectric thin film are produced. The sensor element shape may be circular, square, or fan-shaped. A combination of these shapes may also be used. Further, the crystallinity of each thin film between the back surface of the pressure receiving surface of the diaphragm 6 and the electrode 21 as the lower electrode, or between the electrode 21 and the piezoelectric thin film 22, or between the piezoelectric thin film 22 and the electrode 23 as the upper electrode is improved. A buffer layer may be formed.
FIG. 3 shows a piezoelectric thin film three-layer structure, but it may be a single layer or a multilayer. These are accommodated in the housing 3 and hermetically sealed.

In these sensor elements 24, the diaphragm 6 is distorted with respect to the pressure in the direction of the central axis 5 received during combustion of the engine, and at the same time, the sensor element 24 on the back surface is similarly distorted, and charges corresponding to the distortion amount are generated. The generated electric charge is amplified and output by an amplifier circuit provided on the injector top 4 through the lead wire 7.
A reference time is set based on crank angle information from the engine ECU, and a time difference between outputs from the sensor elements 24 is calculated by an arithmetic circuit described later.

4 to 7 are diagrams showing examples of element arrangement of the combustion pressure sensor. 4 shows three fan-shaped sensor elements 24 arranged at rotationally symmetric positions with respect to the central axis 5, and FIG. 5 shows eight fan-shaped sensor elements 24 arranged at rotationally symmetric positions with respect to the central axis 5. It is.
FIG. 6 is a diagram in which eight sensor elements 24 are arranged at rotationally symmetric positions with respect to the central axis 5 and are also arranged in the radial direction with respect to the central axis. Specifically, eight sensor elements 24 are arranged in a ring shape in the circumferential direction with the central axis 5 as a reference, and a plurality (double in this example) are arranged in the radial direction. By arranging a plurality of sensor elements 24, the combustion starting point information can be calculated with higher accuracy. In particular, by arranging a plurality in the radial direction, it is possible to calculate with higher accuracy when the combustion starting point is in the vicinity of the central axis 5.
FIG. 7 is a diagram in which three circular sensor elements 24 are arranged at rotationally symmetric positions with respect to the central axis 5. The sensor element shape is not limited to a fan shape or a ring shape.

In order to increase the sensitivity of the sensor element, the area occupied by the sensor element 24 with respect to the diaphragm 6 may be increased. Further, in order to increase the measurement accuracy of the combustion start point information, it is also effective to make each sensor element shape a circle and increase the interval as shown in FIG.

By disposing the plurality of sensor elements 24 on the back surface of the diaphragm 6 as shown in the drawings, the combustion starting point can be specified. That is, the flame propagation speed varies greatly depending on the engine speed. Table 1 is a table showing the relationship between the general engine speed and the flame propagation speed.

表１に示す様にエンジン回転数に比例して火炎伝搬速度は速くなる。このことは、燃焼はマクロ的には直進性が高いことを意味する。そのため、非常に短い時間で圧力を測定することにより、燃焼起点からセンサ素子までの時間差をすなわち経路差を測定することができる。圧力測定箇所を３個以上にすることにより、中心軸を法線とする面内の燃焼起点方向を算出することができる。また、エンジンの回転数から火炎伝搬速度を割り出すことにより、気筒内の燃焼起点をより精度良く、３次元的に特定することができる。
なお、回転数と火炎伝搬速度との関係情報は、後述するデータ格納部に記憶されており、回転数情報から火炎伝搬速度が求められるようになされている。

As shown in Table 1, the flame propagation speed increases in proportion to the engine speed. This means that combustion is highly linear in macro. Therefore, by measuring the pressure in a very short time, the time difference from the combustion starting point to the sensor element, that is, the path difference can be measured. By setting the number of pressure measurement points to three or more, the in-plane combustion starting direction with the central axis as the normal line can be calculated. Further, by calculating the flame propagation speed from the engine speed, the combustion starting point in the cylinder can be specified in a three-dimensional manner with higher accuracy.
Note that the relationship information between the rotational speed and the flame propagation speed is stored in a data storage unit, which will be described later, and the flame propagation speed can be obtained from the rotational speed information.

FIG. 8 is a diagram schematically showing combustion in a cylinder. The cylinder 8, the piston 9, the intake valve 10, the exhaust valve 11, and the injector 1 attached to the central shaft. A combustion pressure sensor 2 is attached to the tip of the injector 1. For example, in the case of a diesel engine, combustion is injected in a compression stroke, and temperature and pressure increase, and ignition is performed. At this time, when the position A in FIG. 8 becomes the combustion start point, the pressure change between the plurality of sensor elements attached to the tip of the injector 1 is delayed by the difference between the path B1 and the path B2 from the combustion start point.

FIG. 9 is a diagram showing a change with time of pressure detected by three sensor elements 24 having different arrangements. The output C1 of the combustion pressure sensor element closer to the combustion starting point, the output C2 of the sensor element at a position with a longer path, and the output C3 of the sensor element at a position with a longer path. Calculate the peak time from the time when the crank angle coincides with the reference angle, that is, the reference time (at time zero in the figure) to the peak where the pressure is maximum, and the plane with the central axis as the normal from each peak time difference The combustion start direction can be calculated. Further, if the flame propagation speed is obtained from the engine speed, the combustion starting point can be calculated three-dimensionally in three dimensions.

FIG. 10 is a diagram showing a method of calculating the combustion starting point direction when the number of sensor elements 24 is three. As shown in FIG. 9, the time t1, t2, t3 from the reference point of the crank angle to the peak value of the output C1, output C2, and output C3 of each sensor element is calculated. Parameters k · t1, k · t2, and k · t3. Here, the reason for using the time parameter is that if there is no information on the engine speed from the engine ECU, the flame propagation speed is unknown and the flame propagation path distance from the combustion starting point cannot be calculated. Multiply and use time parameters.

A circle D1, a circle D2, and a circle D3 having the respective time parameters k · t1, k · t2, and k · t3 as radii are drawn around the coordinates of the mounting position (center of gravity) of each combustion sensor element 24, and the intersections of the circles are drawn. Find the coordinates of. A line segment connecting A ′ and the central axis 5 is defined as an intersection when the intersections of the circle D1 and the circle D2, the circle D2 and the circle D3, and the circle D3 and the circle D1 are joined by the lines E1, E2, and E3. F is the in-plane combustion start direction with the central axis as the normal.

FIG. 11 is a perspective view showing a combustion starting point calculation method when three sensor elements are used. As shown in FIG. 9, the time t1, t2, and t3 from the reference point of the crank angle to the output C1, output C2, and output C3 peak values of each sensor element are calculated, and the flame propagation speed is obtained from the engine speed. The flame propagation distances L1, L2, and L3 (not shown) are obtained from the time and the flame propagation speed. A sphere G1, a sphere G2, and a sphere G3 are drawn with the flame propagation distances L1, L2, and L3 as radii around the coordinates of the mounting position (center of gravity) of each sensor element. The intersection of the spheres when these three spheres are drawn is the combustion starting point A.

In FIG. 12, the pressure detection signal 19 from the sensor element 24 is amplified by the amplifier circuit 12, the peak time difference and the combustion start direction are calculated by the arithmetic circuit 13, and the peak time difference and the combustion start point information are sent to the data storage unit 14. FIG. 4 is a series of block diagrams from when the optimum injector condition is calculated by the injector ECU 15 until the injector signal 30 is output.
Each sensor element 24 having a different arrangement position in the combustion pressure sensor 2 detects a pressure increase caused by combustion generated in the cylinder during the engine compression stroke, generates a charge, generates a detection signal 19, and amplifies the circuit board through the lead wire 7. The voltage is converted and amplified by the circuit 12 and the amplified signal 20 is output.

Further, based on the crank angle signal 26 and the amplified signal 20 calculated by the engine ECU 16 based on the crankshaft position signal 25 from the crankshaft position sensor 17, the arithmetic circuit 13 in the circuit board uses the peak time, reference time and Each peak time difference with respect to the reference time is calculated, and data in the combustion start direction is calculated. This peak time and combustion start direction data are recorded in the data storage unit 14 as a combustion start information signal 27.

The combustion starting point information signal 27 is read from the data storage unit 14 as necessary and is read as a combustion starting point information signal 28 and used in the calculation circuit 13 to calculate the fluctuation of the long-period combustion starting point. Fluctuations can be grasped.

Data in the direction of the combustion starting point in consideration of the long-term fluctuation of the combustion starting point is output as the combustion starting point direction signal 29. The combustion start direction signal 29 is sent to the injector ECU 15, where the injector ECU 15 calculates the optimum injector condition so that the combustion start point is on the central axis, and sends the injector signal 30 back to the injector for feedback.

Further, each sensor element is calculated by the arithmetic circuit 13 in the circuit board based on the crank angle signal 26, the rotation speed signal 31 and the amplification signal 20 calculated by the engine ECU 16 based on the crankshaft position signal 25 from the crankshaft position sensor 17. The pressure peak time, the reference time, the flame propagation speed, and the respective peak time differences with respect to the reference time are calculated. From these, the flame propagation distance is obtained, the position data of the combustion starting point is calculated, and the combustion starting point signal 32 is output. The combustion start signal 32 is sent to the injector ECU 15, where the injector ECU 15 calculates the optimal injector condition so that the combustion start point is on the central axis, and sends the injector signal 30 to the injector.

The combustion start signal 32 may be sent to the engine ECU 16. The engine ECU grasps the engine state based on the combustion start signal 32, the crankshaft position signal 25 from the crankshaft position sensor 17 and the camshaft position signal 33 from the camshaft position sensor 18, and sends the engine state signal 34 to the injector ECU15. send. The injector ECU 15 calculates the optimal fuel injection timing, injection time, injection angle, and injection pressure, and transmits an injector signal 30 that brings the combustion starting point closer to the central axis. In addition, the camshaft signal 35 for sending the optimum intake / exhaust valve opening / closing timing is transmitted or fed back.

It goes without saying that the sensor element can be a thin film or a bulk.

As described above, in the combustion pressure sensor 2, at least three sensor elements 24, which are arranged at predetermined positions in the circumferential direction with respect to the central axis 5 and each measure the combustion pressure in the cylinder, and the reference time, And an arithmetic circuit 13 that calculates combustion start point information in the cylinder based on the time of the pressure peak output from the three or more sensor elements 24. This makes it possible to calculate the combustion starting point in the cylinder.

The combustion pressure sensor 2 has three or more sensor elements 24, and the arithmetic circuit 13 determines the central axis 5 based on the reference time and the time of the pressure peak output from the three or more sensor elements 24. The in-plane combustion start direction as a normal line is calculated, and data indicating the combustion start direction is output as combustion start information. This makes it possible to quickly obtain appropriate combustion starting point data.

Further, the combustion pressure sensor 2 has three or more sensor elements 24, and the arithmetic circuit 13 is based on the reference time, the time of the pressure peak output from the three or more sensor elements 24, and the flame propagation speed. A flame propagation distance is obtained, a combustion start position in the cylinder is calculated based on the flame propagation distance, and data indicating the combustion start position is output as combustion start information. Thereby, the position data of the combustion starting point can be easily obtained.

  As described above, the cylinder combustion pressure sensor according to the present invention is useful when detecting the combustion pressure of the cylinders constituting the internal combustion engine in various other applications including the internal combustion engine represented by the engine of the automobile.

DESCRIPTION OF SYMBOLS 1 Injector 2 Combustion pressure sensor 21 Lower electrode 22 Piezoelectric thin film 23 Upper electrode 24 Sensor element 24A Sensor element 24B Sensor element 24C Sensor element 3 Housing 4 Injector top part 5 Center axis 6 Diaphragm 7 Lead wire 8 Cylinder 9 Piston 10 Intake valve 11 Exhaust Valve A Combustion start point A ′ Intersection B1 of lines E1, E2, E3 Flame propagation path B2 from combustion start point A Flame propagation path C1 from combustion start point A Output C2 of sensor element 24A Output C3 of sensor element 24B Output of sensor element 24C D1 Circle D2 centered on sensor element 24A with radius of time parameter k · t1 D2 Circle centered on sensor element 24B and radius of time parameter k · t2 D3 Centered on sensor element 24C and radius of time parameter k · t3 Circle E1 Sensor element 24A center circle and sensor element 24 A straight line E2 connecting the intersection of the center circles A straight line E3 connecting the intersection of the center circle of the sensor element 24B and the center circle of the sensor element 24C. A straight line F connecting the intersection of the center circle of the sensor element 24C and the center circle of the sensor element 24A. A sphere G2 having a flame propagation distance as a center and a sphere G3 having a flame propagation distance as a center and a sphere G3 having a radius as a flame propagation distance from the center. Time t2 until the peak value of the output C1 of the sensor element 24A Time t3 from the reference point of the crank angle to the peak value of the output C2 of the sensor element 24B Time from the reference point of the crank angle to the peak value of the output C3 of the sensor element 24C 12 amplifying circuit 13 arithmetic circuit 14 data storage unit 15 injector ECU
16 Engine ECU
17 Crankshaft position sensor 18 Camshaft position sensor 19 Detection signal 20 Amplified signal 25 Crankshaft position signal 26 Crank angle signal 27 Combustion starting point information signal 28 Reading combustion starting point information signal 29 Combustion starting point direction signal 30 Injector signal 31 Rotational speed signal 32 Combustion Origin signal 33 Camshaft position signal 34 Engine information signal 35 Camshaft signal

Claims (2)

At least three sensor elements arranged at predetermined positions in the circumferential direction with respect to the central axis, each of which measures the combustion pressure in the cylinder;
An arithmetic circuit that calculates combustion start point information in the cylinder based on a reference time and a time of a pressure peak output from the three or more sensor elements;
The combustion starting point information is a combustion starting point direction in a plane with the central axis as a normal line,
The arithmetic circuit calculates time differences t1, t2, and t3 between the reference time and the pressure peaks, and calculates arbitrary time parameters k · t1, k · t2, and k · t3 with k being an arbitrary coefficient. A circle D1, a circle D2, and a circle D3 having the respective time parameters k · t1, k · t2, and k · t3 as radii are drawn with the coordinates of the mounting position (center of gravity) of the sensor element as the center, and the coordinates of the intersection of each circle are drawn. The intersection of the circle D1 and the circle D2, the circle D2 and the circle D3, the circle D3 and the circle D1 connected by the lines E1, E2, and E3 is defined as A ′, and the line that connects A ′ and the central axis. A combustion pressure sensor , wherein the minute F is calculated as the combustion starting point direction . The three or more sensor elements, a combustion pressure sensor according to claim 1, characterized in that a fan shape.

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