KR20180033556A - Method and control system for determining offset for crank angle measurement - Google Patents

Abstract

The present invention relates to a method of determining an offset (38) relating to a crank angle measurement in relation to a cylinder (12) of an internal combustion piston engine (10), wherein the engine (10) is rotated and fuel combustion The reference value for the displayed mean effective pressure is determined and the integral value of the in-cylinder indicated mean effective pressure over a range of crank angles is determined while all the gas exchange valves of the cylinder are kept closed, and the dead point of the piston The crank angle position offset value is determined based on the reference value for the determined integral value of the displayed average effective pressure and the displayed average effective pressure.

Description

Method and control system for determining offset for crank angle measurement

The present invention relates to a method for determining an offset relating to a crank angle measurement in relation to a cylinder of an internal combustion engine. The present invention also relates to a control system for determining an offset relating to a crank angle measurement in relation to a cylinder of an internal combustion piston engine.

The environmental problems in the combustion piston sector are playing an increasingly important role in the development of the field. Strict demands on current regulations and expectations call for the use of accurate control systems for the operation of the engine. In order to provide an accurate control system, reliable information on the institutional situation is required as feedback of the control.

One of the most important combustion parameters associated with the internal combustion engine is the indicated average effective pressure (IMEP). Often the IMEP is calculated cylindrically based on the measurement of cylinder pressure.

US-A-4944271 discloses a control device for controlling the combustion of an internal combustion engine. This control device controls the combustion based on specific drive control parameters such as ignition timing and air-fuel ratio to optimize the value of the specific combustion parameter and the fluctuation range in terms of driving performance. The combustion parameters used to control the combustion process in the internal combustion engine include, for example, the maximum combustion pressure, the crank angle when achieving the maximum combustion pressure, the maximum ascent rate of the combustion pressure, and the indicated average effective pressure. These combustion parameters are determined by the control device based on the pressure profile in the cylinder of the engine detected by the pressure sensor.

Since the pressure sensor is attached directly to the engine, it undergoes a significant temperature change and, as a result, tends to deteriorate over time. In view of this, accurate detection of the pressure by the sensor as well as the initial instability is actually cumbersome.

U.S. Patent No. 4,944,271 discloses that the pressure in the cylinder detected by the pressure sensing means when the crank is at the top dead center position detected by the crank angle sensor is multiplied by the manifold pressure detected by the manifold pressure sensor A method of correcting the pressure measurement by the offset of the pressure sensing means determined in comparison with the pressure sensing means is disclosed. Additional procedures for compensating for the effects of temperature are also disclosed.

It is an object of the present invention to provide a method for determining an offset with respect to a crank angle measurement in relation to a cylinder of the engine in accordance with an internal combustion piston engine whose performance is significantly improved over prior art solutions.

It is also an object of the present invention to provide a control system for determining an offset relating to crank angle measurement in relation to a cylinder of an internal combustion piston engine, which significantly improves performance in comparison with prior art solutions.

The object of the present invention can be substantially satisfied as set forth in the independent claims and other claims that describe other embodiments of the invention in further detail.

When implementing a method for determining an offset relative to a crank angle measurement with respect to a cylinder of the engine in accordance with an internal combustion piston engine,

- the engine is rotated and fuel combustion in the cylinder is suppressed,

- the reference value of the displayed mean effective pressure is determined,

The integral value of the displayed mean effective pressure in the cylinder over a range of crank angles is determined while the combustion chamber of the cylinder is closed, the dead point position of the piston is symmetrically located within said range,

- the crank angle position offset value is determined based on the determined integral value of the displayed mean effective pressure and the reference value for the displayed mean effective pressure.

The crank angle position offset value increases the precision that defines the actual IMEP value, thereby further improving the control of the combustion process of the internal combustion engine. Especially the differences between the dynamics of the cylinder pressure sensors.

The step of suppressing fuel combustion in the cylinder may include actively controlling the interruption of the fuel combustion, or using an engine cycle step in which combustion does not occur, as described herein below.

According to one embodiment of the invention, the method is used to calibrate the crank angle position measurement such that the crank angle position offset value is used for correction of the crank angle position measurement value.

According to one embodiment of the present invention, this method is used to diagnose a position offset in a cylinder pressure measurement.

According to one embodiment of the present invention, the dead point position is the top dead center position and during this method the fuel supply and / or combustion start to the cylinder is suppressed.

When the dead point position is the top dead center position, this method can be executed while the engine is still stopping, but the engine is still rotating due to its inertia. No special equipment is required in this case. The top dead center is preferably during or between compression and power strokes.

The combustion chamber of the cylinder is closed in the four-stroke engine when all the gas exchange valves of the cylinder are kept closed. The combustion chamber is a space limited by the side wall of the cylinder, the upper wall of the cylinder or the top of the cylinder head and piston.

According to one embodiment of the invention, the dead point position is bottom dead center and all the intake valves of the cylinder are closed, so that during this method all the gas exchange valves are kept closed.

According to one embodiment of the invention, the integral of the displayed mean effective pressure in the cylinder is determined using the following equation:

Here, IMEP = integral value of the displayed average effective pressure

θ1 = Starting angle of the crank angle range

θ2 = End angle of the crank angle range

= 기관이 크랭크 각도 θ1 에서 θ2 까지 회전할 때 피스톤이 지나는 실린더의 부피

= Volume of the cylinder through which the piston passes as the engine rotates from crank angle θ1 to θ2

p = pressure inside the cylinder

= 실린더 부피의 도함수

= Derivative of the cylinder volume

According to one embodiment of the present invention, the crank angle range between the start angle and the end angle is symmetrical with respect to the dead point position. In this way, since the reference value for the display average effective pressure is zero, the offset value can be easily determined.

When the dead point position is the top dead center position, the starting angle? 1 of the angular range is 180 degrees or less before the top dead center, and the end angle? 2 of the angular range is 180 degrees or less after the top dead center. According to a particular embodiment of the present invention, the starting angle [theta] 1 of the angular range is less than 100 degrees before the top dead center, and the end angle [theta] 2 of the angular range is less than 100 degrees after the top dead center.

When the dead point position is the bottom dead center position, the starting angle [theta] 1 of the angular range is not more than 100 degrees before the bottom dead center, and the end angle [theta] 2 of the angular range is not more than 100 degrees after the top dead center. The bottom dead center position is preferably during or between the intake stroke and the compression stroke.

The present invention provides a device with significantly improved performance. Position calibration, that is, phase synchronization between the cylinder pressure and the cylinder volume is usually done according to the position of the flywheel, but this calibration is somewhat accurate. Other factors that can affect the calibration are, for example, the measurement delay in the measurement system. The accuracy can be significantly improved by the present invention.

Hereinafter, the present invention will be described with reference to exemplary schematic drawings.

1 shows a control system of an internal combustion piston engine according to an embodiment of the present invention.
2 shows a control system of an internal combustion engine according to another embodiment of the present invention.
Fig. 3 shows an operational example of the present invention.
Fig. 4 shows another working example of the present invention.

1 and 2 schematically illustrate a control system according to an embodiment of the present invention associated with an internal combustion piston engine 10. The engine 10 is shown in a highly simplified manner with reference to only one of the cylinders of the engine. The present invention provides a method and a control system for determining an offset with respect to a crank angle measurement in connection with an engine combustion control system, which can be used to provide more precise control of the engine.

As is known, the main components of the engine are a piston 14 arranged to reciprocate within the cylinder 12 and one or more cylinders 12. Gas exchange in the cylinder 12 is controlled by a gas exchange valve 22, 24 comprising at least one intake valve 24 and at least one exhaust valve 22. Each piston 14 is connected to a crankshaft 16 by a connecting rod 18. Thus, the mechanical dimensions of the component determine the geometry of the combustion chamber 20 and also define the volume through which the piston travels when the piston moves between top dead center and bottom dead center.

A control system (11) for determining an offset relating to a crank angle measurement in relation to a combustion control system of an engine (10) comprises a cylinder pressure sensor (10) configured to measure a pressure in the combustion chamber (20) (26). The control system is also provided with a crankshaft position sensor, or crank angle sensor 28, which provides a signal indicative of the position of the crankshaft 16.

Further, the control system is provided with a cylinder volumetric determination unit 30 configured to receive a signal indicative of the position of the crankshaft 16 from the crank angle sensor 28. The cylinder volumizing unit 30 includes executable instructions for converting the position signals into respective cylinder volumes. It may be based on a predetermined look-up table or function for numerical computation pertaining to instructions. The cylinder volumizing unit 30 is configured to provide a signal indicative of the volume of the cylinder at each crank angle.

The control system 11 also comprises a display mean effective pressure (IMEP) determination unit 32, hereinafter also referred to as an IMEP-unit. The IMEP-unit 32 is connected to a cylinder pressure sensor 26 and is adapted to receive a pressure signal from the cylinder pressure sensor 26. The IMEP-unit 32 is also connected to the cylinder volumizing unit 30 and is adapted to receive a signal indicative of the cylinder volume. The IMEP-unit 32 is also coupled to a crank angle sensor 28 and is adapted to receive a signal indicative of the position of the crankshaft 16 from the crank angle sensor 28. The IMEP-unit 32 is provided with an executable instruction for determining the integral value of the displayed average effective pressure in the cylinder 12. [ In particular, the instruction includes an instruction to determine an integral value of the displayed mean effective pressure using the following equation:

Here, IMEP = integral value of the displayed average effective pressure

θ1 = Starting angle of the crank angle range

θ2 = End angle of the crank angle range

= 기관이 크랭크 각도 범위 θ1 에서 θ2 에 걸쳐 회전할 때 피스톤이 지나간 실린더의 부피, 실린더 부피 결정 유닛 (30) 으로부터 획득 가능함

= Volume of the cylinder past the piston when the engine rotates over the range of crank angles? 1 to? 2, obtainable from the cylinder volumetric unit 30

p = cylinder internal pressure, obtainable from the cylinder pressure sensor 26

= 실린더 부피의 도함수.

= The derivative of the cylinder volume.

The control system also includes a controller unit 36 and a setpoint unit 34. The set point unit 34 is configured to provide a reference value for the controller unit 36. [ The controller unit 36 is connected to the setpoint unit 34 and the IMEP- The controller unit 36 is configured to receive the integrated value of the displayed mean effective pressure from the IMEP-unit 32 and the reference value provided by the set point unit 34. [ The controller unit 36 is provided with an executable instruction to provide a crank angle position offset value as its output 38. [ The reference value provided by the set point unit represents the target integral value of the displayed mean effective pressure for a given crank angle range and the integral value of the displayed mean effective pressure from the IMEP unit 32 represents the feedback value from the engine.

Figure 1 shows a control system 11 for determining an offset with respect to the crank angle range through which the piston passes the top dead center position. To use the control system when the piston passes the top dead center, the control system is provided with a command to disallow fuel entry into the cylinder 12 during the determination of the offset. According to one embodiment of the present invention, the IMEP-unit 32 is adapted to provide the output signal shown by the line 33 extending from the IMEP-unit to the fuel injector 23, The control system (not shown) omits fuel entry into the combustion chamber and / or ignition in the combustion chamber. This may be achieved by controlling the fuel injector 23 so as not to inject fuel during the cycle. Therefore, when the present method is carried out, the supply of fuel to the cylinder and / or the start of combustion is suppressed.

It is also possible to consider performing this method while the fuel is stopped to stop the engine but the engine is still rotating due to inertia. Thus, the determination of the offset is performed while the intake valve 24 and the exhaust valve 22 are closed at the same time, and no combustion takes place in the method and / or combustion of the fuel is impossible.

Figure 2 shows a control system 11 for determining the offset with respect to the crank angle range through which the piston passes through the bottom dead center position. According to a first embodiment of the present invention, in order to use the control system when the piston passes through the bottom dead center, the control system maintains the closed intake valve 24 while closing the intake valve 24 and determining the offset And the like. The cylinder 12 is now in the intake-compression stroke stage and the exhaust valve (s) 22 are closed in any case based on normal control of the gas exchange valve. According to this embodiment of the present invention, the IMEP-unit 32 is configured to provide the output signal shown in line 33 'extending between the IMEP-unit 32 and the intake valve 24 control system, Based on this, the combustion control system (not shown) of the engine controls that the intake valve 24 is closed while the method is being carried out. Thus, the determination of the offset is performed while the intake valve 24 and the exhaust valve 22, i.e., all of the gas exchange valves are closed at the same time, and no combustion takes place in the process and / or combustion of the fuel is impossible.

According to a second embodiment of the present invention, in order to use the control system when the piston passes through the bottom dead center, the control system performs the determination of the offset while the intake valve 24 and the exhaust valve 22 are simultaneously closed Command. Since the cylinder 12 is in the stage of the intake-compression stroke, the exhaust valve (s) 22 are closed in any case based on normal control of the gas exchange valve. In this embodiment, the intake valve 24 is prematurely closed before bottom dead center for other reasons, and the information that the valve (s) has been closed is communicated to the IMEP-unit via the communication line 33 ' It is used as a signal to allow initiation.

Although an embodiment for determining an offset value near the top dead center and near the bottom dead center is separately disclosed, it may be considered to provide two alternatives to the engine. In this case, the determination of the offset value may be carried out using one of the means depending on, for example, the operating environment of the engine. For example, early closing of the intake valve is more appropriate than providing misfire in the cylinder at the high load of the engine.

The control system operates as disclosed in the method for determining the offset relating to the crank angle measurement in relation to the cylinder of the internal combustion piston engine described below. A method for determining an offset relating to a crank angle measurement with respect to a cylinder of an internal combustion piston engine includes the following steps. First, it is essential that at least the cylinder in which the method is implemented is such that fuel combustion is suppressed during the practice of the present method, and that the engine rotates or rotates the engine over at least a predetermined crank angle range. To implement this method, a reference value for the displayed average effective pressure is determined by the set point unit 34. [ The integrated value of the displayed mean effective pressure in the cylinder is determined over a range of crank angles where the combustion chamber is closed, that is, all of the gas exchange valves of the cylinder are kept closed (the dead point position of the piston is located within this range) The position offset value is determined based on the determined integral value of the displayed average effective pressure and the reference value of the displayed average effective pressure.

The basic principle of the method is described below with reference to Fig. In this case, the method is performed over a range in which the TDC of the piston is located. 3 shows a chart in which the abscissa represents the crank angle CA indicated by the abscissa and the ordinate represents the normalized value of the variables, the variables being the difference between the derivative of the cylinder volume 42 and the fuel combustion during the practice of the method Represents three different situations of a specific pressure in the cylinders 40.1, 40.2, 40.3. In other words, the engine is so-called motorized. For example, the starting angle θ1 of this range is 180 degrees before the top dead center, and the end angle θ2 of this range is 180 degrees after the top dead center. It should be noted that the range used may vary as long as the combustion chamber is closed by a gas exchange valve. However, if the range is too narrow, the sensitivity of the calculation to the misalignment increases. The integral of the displayed mean effective pressure is determined by the equation shown above.

This method is carried out when the crank angle range is symmetrical with respect to the dead point position. In this case, the start crank angle is before the dead point position as the end crank angle is behind the dead point position, and the reference value is zero. Therefore, the deviation of the integral value of the display average effective pressure from 0 represents the offset state. It can be seen that this equation can be interpreted as the sum of the product of the cylinder pressure and the derivative of the cylinder volume and zero IMEP can only be obtained when the volume is at the same phase as the pressure (40.1). The phase shift that moves pressure to the left (40.2) suggests a negative IMEP, and in the case of 40.3 it is reversed.

The range may also be selected differently. For example, when the range is near TD, the range can be substantially wide due to the valve timing of the four-stroke engine during the compression and power stroke phases while motoring the engine. For proper and accurate calculation, the starting angle [theta] 1 was found to be at least 100 degrees before the top dead center, and the end angle [theta] 2 of the range was at least 100 degrees after the top dead center.

Fig. 4 shows a chart similar to Fig. 3, wherein the angular range is near the BDC of the cylinder during the intake-compression phase of a four-stroke engine. The abscissa represents the crank angle CA indicated on the road and the ordinate represents the normalized value of the variables which are the three conditions of the differential pressure of the cylinder volume 42 and the measured pressures in the cylinders 40.1, 40.2, 40.3.

In this case, the method is also carried out when the crank angle range is symmetrical with respect to the dead point position. In this case, the start crank angle is before the dead point position as the end crank angle is behind the dead point position, and the reference value is zero. Therefore, the deviation from zero and the integrated value of the display average effective pressure indicates the offset state. This equation can be interpreted as the sum of the product of the cylinder pressure and the derivative of the cylinder volume, and zero IMEP can only be obtained when the volume is at the same volume as pressure (40.1). The phase shift that moves the pressure to the left side (40.2) implies the negative IMEP and reverses in the case of 40.3.

The range may also be selected differently. For example, when the range is near the bottom dead center, the usable range is largely limited by the time required for the intake valve to open during the intake stroke. However, particularly when the engine is supercharged, the intake valve can be closed well before the bottom dead center, in which case the raised charge pressure compensates for a shorter intake valve opening time, i.e. a faster closing timing. For proper and accurate calculation, the starting angle? 1 was found to be at least 100 degrees before the bottom dead center, and the end angle? 2 of the range was at least 100 degrees after the bottom dead center. It should be noted that the range used in this embodiment can be changed as long as the combustion chamber is closed by the gas exchange valve. However, if the range is too narrow, it is inevitable to greatly increase the sensitivity of the calculation to misalignment, so the intake valve should actually be opened as soon as possible.

While the present invention has been described by way of example with reference to what are presently considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various combinations and modifications of the features as defined in the appended claims, But should be understood to include some other applications that are included within the scope of the present invention. Details referred to in connection with any of the above embodiments may also be used in connection with other embodiments where technically feasible.

Claims (12)

A method of determining an offset (38) with respect to a crank angle measurement in relation to a cylinder (12) of an internal combustion piston engine (10)
The engine 10 is rotated, fuel combustion in the cylinder is suppressed during the method,
A reference value for the displayed average effective pressure is determined (34)
The integral value of the in-cylinder indicated mean effective pressure is determined (32) through the crank angle range while the combustion chamber of the cylinder is closed (32), the dead point position of the piston is symmetrically located within the crank angle range,
Wherein the crank angle position offset value is determined based on the determined integrated value of the displayed mean effective pressure and the reference value for the displayed mean effective pressure. The method according to claim 1,
Is used to calibrate the crank angle position measurement such that the crank angle position offset value is used for correction of the crank angle position measurement value. The method according to claim 1,
And wherein the method is used to diagnose a position offset in a cylinder pressure measurement. The method according to claim 1,
Characterized in that the dead point position is a top dead center position and fuel supply and / or combustion initiation to the cylinder during the method is inhibited. 5. The method of claim 4,
Characterized in that the method is carried out while the engine is still rotating due to inertia of the engine during the stopping of the engine. The method according to claim 1,
Wherein the dead point position is a bottom dead center position and the intake valves of the cylinder are closed such that all gas exchange valves remain closed during the method. The method according to claim 1,
Wherein the integral of the displayed average effective pressure in the cylinder is determined using the following equation:

Here, IMEP = integral value of the displayed average effective pressure
θ1 = Starting angle of the crank angle range
θ2 = End angle of the crank angle range

= The volume of the cylinder past the piston as it rotates from crank angle θ1 to θ2
p = pressure inside the cylinder

= Derivative of the cylinder volume 8. The method according to claim 4 or 7,
Wherein the starting angle of the range is less than 180 degrees before the top dead center and the end angle of the range is less than 180 degrees after the top dead center. 9. The method of claim 8,
Wherein the starting angle of the range is less than 100 degrees before the top dead center and the end angle of the range is less than 100 degrees after the top dead center. 8. The method according to claim 6 or 7,
Wherein the starting angle of the range is less than 100 degrees before the bottom dead center and the end angle of the range is less than 100 degrees after the bottom dead center. A control system for determining an offset relating to a crank angle measurement in relation to a cylinder of an internal combustion piston engine (10)
- a cylinder pressure sensor (26) adapted to measure the pressure in the combustion chamber (20) of the cylinder (12) and to provide a pressure signal,
- a crankshaft position sensor (28) providing a signal indicative of the position of the crankshaft (16) of the engine (10)
A cylinder volume determining unit (30) adapted to receive a signal indicative of the position of the crankshaft (16) from a crank angle sensor (28) and to provide a signal indicative of the volume of the cylinder at each crank angle, The determining unit 30 includes a cylinder volume determining unit 30 including executable instructions for converting a position signal to a respective cylinder volume,
- an indicator connected to the cylinder pressure sensor (26) and the cylinder volumetric unit (30) and adapted to receive a pressure signal from the cylinder pressure sensor (26) and to receive a signal indicative of the volume of the cylinder (IMEP) determining unit 32 is further connected to the crank angle sensor 28 and receives a signal indicative of the position of the crankshaft 16 (IMEP) determining unit 32, which is adapted to determine an integral of the displayed mean effective pressure within the cylinder 12,
A controller unit 36 and a set point unit 34,
The set point unit is adapted to provide a reference value for the controller unit (36) connected to the set point unit (34) and the display mean effective pressure (IMEP) determination unit (32)
The controller unit 36 is adapted to receive an integrated value of the displayed mean effective pressure from the display mean effective pressure (IMEP) determining unit 32 and a reference value provided from the set point unit 34, 36) is provided with an executable instruction for providing a crank angle position offset value. 12. The method of claim 11,
11. A control system according to any one of the preceding claims, wherein the control system is arranged to perform the method according to any one of claims 1 to 10.

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