JP4250463B2 - Method of operating adjustment member of crosshead type piston engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This onset Ming relates actuation of the adjusting member of the 2-stroke engine the process is adjusted to be periodically repeated in the engine by the adjusting member.
[0002]
[Prior art]
An example of a regulating member that is actuated is a fuel dosing valve in which the periodically repeated process is fuel injection. The purpose of operating this fuel dosing valve is to adjust the fuel injection so that the fuel injection pressure varies according to a predetermined plan in each operating cycle of the engine and each of the cylinders. This is called pressure adaptation . The fuel injection pressure is assumed to have a known relationship to the injected fuel flow. The purpose of pressure adaptation is to adapt engine operating conditions to different demands such as load conditions and fuel quality, to optimize fuel consumption and to minimize fuel consumption.
[0003]
In a piston engine , it is crucial to the thermodynamic performance of the engine that the maximum and average command injection pressures commanded by the controller are obtained in each cylinder and engine operating cycle. Variations in the mechanical / hydraulic components used in the fuel injector will affect the performance of the control loop that adapts the injection pressure. It is important to obtain the best robustness possible in the control loop.
[0004]
EP 612 920 discloses a fuel injection device that opens or closes when the pressure characteristic with respect to time is determined by the cam tip and rising ramp and the solenoid actuated valve is determined by the processor. The effective part of the ramp can be controlled to adapt the injection pressure.
[0005]
DE 19 726 589 discloses a self-adjusting adjustment device that can achieve a quick adaptation of a reference valve with minimal overswing by stepwise adaptation of the adjustment parameters.
[0006]
DE 3 825 138 discloses a device with a calculation unit that receives both the drive current signal and the resulting position of the adjusting member. The frictional force is calculated and fed back to the adjustment point. Velocity and magnetic driving force are also calculated and fed back to the adjustment point as steady state correction signals for slow changes.
[0007]
US 4 490 791 discloses an apparatus for controlling acceleration, where data from observed surging is stored and used later to avoid surging under similar conditions.
[0008]
GB 2 210 181 discloses an instantaneous adaptive control method for a fuel control valve in which disturbances such as friction in the control valve are reduced.
[0009]
[Patent Document 1]
EP 612 920
[0010]
[Patent Document 2]
DE 19 726 589
[0011]
[Patent Document 3]
DE 3 825 138
[0012]
[Patent Document 4]
US 4 490 791
[0013]
[Patent Document 5]
GB 2 210 181
[0014]
[Problems to be solved by the invention]
Each of the devices in the prior art documents mentioned above does not have any means for automatically compensating for the deviation, so that possible deviations in the position of the adjusting member from the desired position. Suffers the disadvantage of being repeated in each operating cycle. In the case of a piston engine , for example a crosshead type two-stroke engine with such a prior art device for adapting the fuel injection pressure, this results in an engine operating condition and in particular a fuel combustion process. It is not as desired and may not be as expected. Thus, the engine will probably not operate as desired and expected. This can lead to increased fuel consumption or the injection of certain combustion products above acceptable levels.
[0015]
[Means for Solving the Problems]
The present invention solves this problem by an automatic adaptation method that compensates for slow changes in engine component parameters. In accordance with the present invention, in the first operating cycle of the engine, the actual position of the adjusting member is observed and this predefined time at a predefined time related to the timing pulse obtained by rotation of the engine crankshaft. Compared to the desired position in time. The difference between the desired position and the actual position of the adjustment member causes a correction to the drive signal that drives the adjustment member for use at a time corresponding to a predetermined time in the next operating cycle of the engine. Used for. This automatically corrects possible deviations of the position of the adjustment member from the desired position, and in the next operating cycle, the adjustment member will take the desired position at a time corresponding to a predefined time. Let's go. The adjusting member is advantageously a fuel delivery valve with a spool.
[0016]
The method preferably includes such a correction step to be performed at a plurality of predefined times during each operating cycle, preferably at a predefined sampling frequency. This will cause the adjustment member to take virtually the desired position at any time in the cycle, not just one special time in the engine's operating cycle.
[0017]
The method preferably includes such correction steps to be performed in multiple engine operating cycles. Thereby, possible residual errors in the position of the adjustment member will be further reduced and eventually eliminated.
[0018]
In the preferred embodiment of the present invention, the periodically repeated process is fuel injection, but other processes that require correct timing and control in the piston engine can also be adjusted by the method of the present invention. One example is the discharge of combustion products in which a hydraulic actuator is adjusted to open or close a cylinder exhaust valve . The position of the hydraulic actuator can be used as a parameter representing the process to be adjusted. The discharge valve may be closed by an air spring containing a bellows with an enclosed volume of air. The instantaneous air pressure in the bellows is inversely proportional to the bellows volume and is therefore proportional to the position of the exhaust valve . It is therefore also possible to observe the air pressure in the bellows and use the observed pressure as a parameter representing the process to be adjusted. Another example of a process to be regulated is piston lubrication and cylinder lining where correct timing is essential but pressure fit is less important.
[0019]
It may be desirable to inject non-flammable, thermodynamically active material into the engine cylinder simultaneously with fuel injection. Such materials can be used to influence the thermodynamic process and can be injected separately or together with the liquid or gaseous fuel. Advantageously, the water injection can be timed and the injection pressure characteristics can be adapted to follow the predetermined characteristics by the method of the invention.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a fuel injection device controlled by a hydraulic pump for use, for example, in a crosshead type 2-stroke piston engine. The hydraulic apparatus includes a fuel pump 10, which has a first piston 11 and a second piston 12 that is smaller than the first piston 11 and coupled to the first piston 11. The first piston 11 drives the second piston 12. The load 13 represents a traditional device with a high-pressure fuel injection pump having a “load” that includes an injection nozzle mounted in the cylinder of a piston engine to inject fuel into the cylinder. Therefore, in particular, this load represents the pressure drop before and after the fuel injection nozzle and the pressure in the cylinder. Due to the size difference between the first piston 11 and the smaller second piston 12, the fuel injection pressure will be increased by a rate equal to the ratio of the working area of the first piston to the second piston. Let's go.
[0021]
The fuel injection device has a hydraulic pump 14 that pumps hydraulic fluid from the reservoir 15 to the control valve 16. The control valve 16 has, for example, a movable valve spool 17 that is driven by a driver 18 that is driven electrically or hydraulically.
[0022]
The controller 19 receives a crankshaft position signal via line 20 from a crankshaft position sensor (not shown). When the crank position signal is related to the trigger signal, i.e. synchronized to the angular position of the crankshaft, the controller 19 triggers the drive supplied to the driver 18 that drives the spool 17 of the control valve 16. A signal D is generated.
[0023]
The position of the valve spool 17 is assumed to have a known relationship to the fuel injection pressure. By correctly positioning the spool in the control valve, the injection pressure can be controlled with a corresponding accuracy, ie kinetically, at any time. In particular, in each operating cycle of the engine, the injection pressure is adapted to follow any desired characteristics by positioning the spool according to a predetermined setup, whereby the fuel injection pressure is closely related to the crankshaft angle. Can be changed in a controlled manner. Accordingly, the control valve 16 is also referred to as a fuel delivery valve because it controls the delivery of fuel to the engine.
[0024]
An encoder 21 for detecting the position of the spool is provided. The encoder 21 changes position to an electrical signal P, which can be a digital encoder or a potentiometer with a wiping contact coupled to a valve spool. The encoded digital or analog signal P representing the spool position is fed back to the controller 19.
[0025]
FIG. 2 shows an example of a desired value and an actual value of the parameter P representing the injection pressure in the crosshead type 2-stroke piston engine. The parameter P is an output from the encoder 21 and a signal extracted at a predetermined sampling during the engine operation cycle. FIG. 2 shows a desired value P _desired (t _i ) and an actual value P _actual (t _i ) at each sampling time t _i . Due to the drawbacks of the prior art method of adjusting the fuel delivery valve, actual values having deviations from the desired values, which are quite common in the prior art, are shown. Such a deviation is avoided by the present invention described below.
[0026]
The above apparatus operates as follows. In each engine operating cycle, at a predefined time t _i related to the timing pulse obtained by rotation of the engine crankshaft, the spool position is extracted by a sampling frequency that allows an appropriate time resolution of that position. Is done. The actual position P _actual (t _i ) of the valve spool is measured by the encoder 21, and the output signal from the encoder is used as an input to the controller 19. The controller compares the observed _actual position P _actual (t _i ) with the desired position P _desired (t _i ) at the same sampling time t _i and the difference between the desired value and the actual value at time t _i . Calculate the error as P _desired (t _i ) −P _actual (t _i ). The controller then calculates the drive signal D necessary to drive the valve spool 17 to assume the desired position at the next sampling time t _{i + 1} in the same engine operating cycle. This is a quick real-time adjustment of the valve spool position, thereby providing a basic pressure fit in each operating cycle.
[0027]
However, the above pressure adaptation presupposes a complete or nearly complete model of the process to be tuned, and in particular assumes that the values of the engine components will ultimately remain constant. . The above method does not take into account slow changes such as wear and deterioration of engine components, and any observed difference P _desired (t _i ) between the desired and actual values of the parameter. -P _{actual (t i)} remains constant from one cycle to the next. After all, this method requires improvement.
[0028]
In accordance with the present invention, in addition to the above, an adaptation process is performed, which compensates for both possible deviations of the spool position from the desired position (due to incomplete adjustments and possible slow changes). The
[0029]
In accordance with the present invention, the adaptation process corrects such observed differences (or errors) in the next operating cycle, which is done as follows. Based on the calculated difference P _desired (t _i ) −P _actual (t _i ) between the desired value and the actual value at time t _i in the first operating cycle C 1, the controller calculating a correction .DELTA.DT _i to the drive signal D is used to drive the valve spool 17 in one operation cycle. The corrected drive signal D + ΔDt _i is used in the next operation cycle, and in the next operation cycle C2, the valve spool 17 is set to take a desired position at the time of sampling corresponding to the sampling time t _i in the first operation cycle C1. Expected to drive. If the difference between the desired value and the actual value of the parameter P is still present in cycle C2, the adaptation process is further corrected in another next operating cycle or the like. Will do so.
[0030]
In each engine operating cycle, fuel injection is synchronized to crankshaft rotation by a crankshaft position signal received via line 20. Fuel injection is initiated at an angular position of the crankshaft that is independent of each of the engine's cylinders and depending on the actual operating conditions of the engine. In each operating cycle, the timing is referred to as a crankshaft position signal.
[0031]
In particular, the moving parts, including driver 18, valve spool 17, hydraulic fluid, pump pistons 11 and 12, and pumped fuel, each have a physical mass that represents some kind of inertia. Due to the inertial force, the drive signal D must be applied to the driver 18 at some time before the desired injection pressure represented by the parameter P is achieved. This time depends on several factors such as the dynamic mass or inertia of the moving part, the “distance” to which the dynamic mass is to be moved and the force applied. Those skilled in the art will know how to take such factors into account. Here, the time t _i is used to indicate when to associated event occurs. Thus, when the corrected drive signal D + ΔDt _i is adapted at the appropriate time, it drives the valve spool 17 to its desired position at a time t _i that is not in the time applied to the driver 18 but in the cycle C2. Drive signal.
[0032]
The engine power is adjusted by changing the fuel injection phase period. This is done by interrupting the fuel injection at various times and by causing the injection pressure to essentially follow the same injection pressure characteristics until the injection is interrupted. When high engine power is required, fuel injection is interrupted at a later time, thereby extending the fuel injection time and injecting a greater amount of fuel. Similarly, when low engine power is required, fuel injection is interrupted earlier, thereby shortening the fuel injection time and injecting a smaller amount of fuel. The time when fuel injection is interrupted is referred to as an “index”. Thus, a higher index value corresponds to a high engine power and a low index value corresponds to a low engine power.
[0033]
When the engine power is reduced, the index is reduced from one engine cycle C _i to the next engine cycle C _{i + 1} and the adaptation process for the next engine cycle described above is the first engine to be repeated in cycle C _{i + 1} . It is performed only for the desired position of the fuel metering valve spool in the cycle C _i. Since the next injection stage IP _{i + 1} is shorter than the previous injection stage IP _i, all the desired valve spool positions in the next injection stage IP _{i + 1} except those in the valve closing stage are those in the previous stage IP _i . The adaptation process as described above is carried out until a new (ie, earlier) interruption time at which the closure phase is initiated.
[0034]
When the engine power is increased, the fuel injection phase is extended from one engine cycle C _i to the next engine cycle C _{i + 1} . Since the next injection stage IP _{i + 1} is now longer than the first injection stage IP _i , the desired new valve spool at a later time than during the interruption of fuel injection in the first engine cycle is the first injection stage IP _{i + 1.} They will not have their desired response time in stage IP _i . For such a new open position of the valve spool, there is no correction ΔD for the drive signal D stored from the first engine cycle. Instead, the stored correction from the previous engine cycle is used. Such a previous engine cycle is preferably the last cycle in which the engine has been operated under the new operating conditions. Typically, such engine cycles will typically be “old” cycles, ranging from minutes or hours to perhaps days or more.
[0035]
The fitting process is an automatic correction process whereby the device senses deviations from the desired position of the valve spool. The adaptation process is preferably performed at each operating cycle of the engine. If complete correction is not obtained in the first run of the adaptation process, this process will be repeated and will converge after only 2-3 runs. If the engine components included in the process to be calibrated are worn and deteriorated, for example, if the above adaptation process is not used, the result is that further degradation from the desired value due to engine performance deterioration. Deviations will occur. According to the adaptation process of the present invention, such variations will be compensated.
[0036]
Although the present invention has been described above with respect to the fuel injection device under pump control, it will be apparent to those skilled in the art that the present invention can also be applied to an accumulator injection system with appropriate modifications.
[0037]
【The invention's effect】
In this way, the method of the present invention can compensate for slowly occurring changes such as engine component degradation and wear.
[0038]
[Industrial applicability]
The method of the present invention may also be applied to the adjustment of periodically repeated processes other than piston engines. With a few suitable adaptations, the method of the invention can be applied to periodically repeated processes such as injection of melt molding material in an automatic injection molding machine. Industrially, many automated processes are repeated periodically, and those skilled in the art can apply the method of the present invention to many such processes.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a hydraulic apparatus controlled by a pump for fuel injection according to the present invention.
FIG. 2 is a diagram showing a desired value and an actual value of a parameter P representing fuel injection pressure in a crosshead type 2-stroke piston engine.
[Explanation of symbols]
10 fuel pump, 11 first piston,
12 second piston, 13 load, 14 hydraulic pump,
15 reservoir, 16 control valve, 17 valve spool,
18 drivers, 19 controllers, 21 encoders

Claims (11)

The adjustment member is driven by the drive signal (D), adjusts the process that is repeated periodically in the engine, determines a monitorable parameter (P) that represents the _actual value of the process (P _actual ), and _sets the desired parameter A method of operating a regulating member of a crosshead type piston engine, which is compared with a value of (P _desired ),
In the first operating cycle of the engine (C1), using the drive signal _{D ti, C1} for driving the adjusting member, the actual value _P actual are to be eventually obtained the parameters representing the process _{(t i, C1} ) At time t _{i, C1} and comparing the actual value of the determined parameter with the desired value P _desired (t _{i, C1} ) of the parameter at time t _{i, C1} ;
The difference between the desired value and the actual value of the parameter P _desired (t _{i, C1} ) −P _actual (t _{i, C1} ) and the desired value of the parameter at the next time t _{i + 1} in the first operating cycle of the engine. Based on the value, a drive signal (D _{t + 1, C1} ) is generated for driving the adjusting member to achieve the desired value of the parameter at the next time t _{i + 1} in the first operating cycle of the engine. And including steps,
Based on the difference P _desired (t _{i, C1} ) −P _actual (t _{i, C1} ) between the desired value and the actual value of the parameter determined in the first operating cycle of the engine To achieve the desired value of the parameter at time t _{i, C2} corresponding to time t _{i, C1} in the first operation cycle of the engine in the second operation cycle (C2) of the engine following the first operation cycle of Then, a correction ΔDt _{i, C2} for the drive signal for driving the adjusting member is generated, and the corrected drive signal Dt _{i, C2} = Dt _{i, C1 at the} time t _{i, C2} in the second operation cycle of the engine. + ΔDt _{i, C2} is used to drive the adjusting member. The method of claim 1, comprising:
The method wherein the periodically repeated process is fuel injection and the adjustment member is a fuel delivery valve . 3. The method of claim 2, wherein the parameter representing the actual value is a position of a spool within the fuel delivery valve. The method of claim 1, wherein the represented actual value is a fuel injection pressure. 5. A method as claimed in any one of claims 1 to 4, wherein the method is repeated a plurality of times in the first and second operating cycles. 6. A method according to any one of the preceding claims, wherein the method is repeated over a plurality of operating cycles. 2. The method of claim 1, wherein the periodically repeated process is combustion product discharge and the adjustment member is an exhaust valve actuator. 2. The method of claim 1, wherein the periodically repeated process is piston lubrication and cylinder lining, and the adjustment member is a lubricant dosing valve. 2. The method of claim 1, wherein the periodically repeated process is injection of a non-flammable thermodynamically active material into a combustion chamber of an engine. The method of claim 1, comprising:
  The period of the periodically repeated process varies between one operating cycle of the engine and another operating cycle, each time t in the second operating cycle. _i , The correction ΔDt for the drive signal _{i, C2} The method is taken from each previous operating cycle. The method of claim 10, comprising:
  The process in which each previous operating cycle is repeated periodically is time t. _i The method, which is the last operating cycle performed in

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