JP2015502483A - Diesel engine apparatus and method for varnish deposition control - Google Patents

Abstract

The present invention relates to a method for controlling varnish deposition in a variable geometry turbine (VGT) of a diesel engine turbocharger. In accordance with the present invention, it is determined whether the operating parameters are at a predetermined level for initiating a varnish deposition control sequence. When it is determined that the operating parameter is at a predetermined level, the varnish deposition control sequence is started. The sequence increases the exhaust temperature upstream of the VGT to a first exhaust temperature, and increases the exhaust temperature to the first exhaust temperature. Vary between large aperture diameters. In addition, a diesel engine device is also provided. [Selection] Figure 1

Description

  The present invention relates to a method for varnish deposition control and a diesel engine apparatus in a variable form turbine (VGT) of a diesel engine turbocharger.

  Varnishes are undesired, usually glossy films, consisting primarily of unburned hydrocarbons. In turbocharged diesel engines, this condition is often caused by incomplete combustion in a relatively cold engine cylinder. Semi-burning fuel tends to harden and stick on the turbocharger nozzle and usually requires replacement of the turbocharger.

  In conventional diesel engines, it is known that VGT nozzles circulate periodically through open and closed positions to facilitate the removal of accumulated soot. Also, perform “heating mode” operation aimed at facilitating cleaning, regeneration, or heating of exhaust aftertreatment system components such as diesel oxidation catalyst and diesel particulate filter by raising exhaust temperature. Is also known. It has also been found that soot deposits are likely to be generated during idling for a long time at a low temperature, and it is effective to heat the exhaust gas periodically to facilitate soot removal. However, these operations usually do not prevent or remove varnish buildup.

  Accordingly, it is desirable to provide a method for controlling varnish deposition. It would also be desirable to provide a diesel engine arrangement that facilitates control of varnish deposition.

  According to one aspect of the invention, a method is provided for controlling varnish deposition in a variable geometry turbine (VGT) of a diesel engine turbocharger. According to the method, it is determined whether the operating parameter is at a level defined to initiate the varnish deposition control sequence. If it is determined that the operating parameters are at a predetermined level, a varnish deposition control sequence is initiated. The sequence relates to the steps of increasing the exhaust temperature upstream of the VGT to the first exhaust temperature and increasing the exhaust temperature to the first exhaust temperature, and the opening diameter of the VGT nozzle is changed to a small opening diameter and a large opening diameter. And the steps to change between.

  In accordance with another aspect of the present invention, a diesel engine apparatus includes a diesel engine, a turbocharger including a variable form turbine (VGT) downstream of the engine, and a varnish for operating parameters to control varnish deposition on the VGT. A means for determining whether the level is a predetermined level for starting the deposition control sequence, and a configuration for starting the varnish deposition control sequence when the determination means determines that the operating parameter is at a predetermined level. Control device. The varnish deposition control sequence includes the steps of increasing the exhaust temperature upstream of the VGT to the first exhaust temperature and increasing the exhaust temperature to the first exhaust temperature. And a step of changing between the large opening diameters.

  The features and advantages of the present invention will be better understood by reading the following detailed description in conjunction with the drawings in which like numerals represent like elements.

1 is a schematic view of a diesel engine device according to an aspect of the present invention. It is a flowchart which shows the step in the deposition control method of the varnish by another aspect of this invention.

  FIG. 1 schematically shows a diesel engine device 21 according to one embodiment of the present invention. The apparatus 21 consists of a diesel engine 23 and a turbocharger 25 including a variable form turbine (VGT) 27 downstream of the engine. Means are provided for determining whether the operating parameter is at a defined level for initiating a varnish deposition control sequence to control varnish deposition on the VGT 27. The detailed means depends on what the operating parameters are. The operating parameters may be a function of some specific parameters, such as engine operating parameters or modeling based parameters, and may involve several specific sensors, estimates, or decisions. The controller 29 is configured to start the varnish deposition control sequence when the determining means determines that the operating parameter is at a predetermined level.

  In the varnish deposition control sequence, the nozzle opening of the VGT nozzle 33 is slightly opened in relation to the steps of increasing the exhaust temperature upstream of the VGT 27 to the first exhaust temperature and increasing the exhaust temperature to the first exhaust temperature. Between the caliber and the large aperture (schematically indicated by the dotted line in FIG. 1), for example, the VGT wing is between the maximum open aperture (100%) and the maximum closed aperture (0%), or from maximum open to maximum The step of changing by moving between several positions until closure. By describing the change in nozzle opening diameter as “in relation to” an increase in exhaust temperature, the change in nozzle opening diameter is performed simultaneously with the temperature increase, or at different times, for example after each temperature increase or total temperature increase. In particular, it is intended to convey the relationship between the change in nozzle opening diameter and the rise in exhaust temperature, particularly with respect to the varnish deposition control sequence.

  In addition, the change in nozzle opening diameter and the increase in exhaust temperature performed during the “varnish deposition control sequence” may occur randomly in relation to each other during engine operation, or may be varnished in relation to each other. It is also intended to contrast with changes in nozzle opening diameter and exhaust temperature rise, which are not associated with a specific sequence for deposition control. For example, closing the VGT nozzle opening will increase the exhaust temperature upstream of the VGT, but these two steps are at a level where the operating parameters are set to initiate the varnish deposition control sequence. Except when executed in response to such determination, they are not executed in conjunction with each other as steps of the varnish deposition control sequence.

  While not intending to be bound by theory, changing the aperture diameter, usually performed at least in connection with a type of VGT having movable wings, usually rubs the surface of the VGT, causing varnish or soot deposits to There is an effect to remove. Increasing the temperature upstream of the VGT promotes further combustion of the hydrocarbons in the exhaust stream, depending on the temperature, thereby allowing the hydrocarbons to form varnish deposits on the VGT components. The varnish deposit can be turned into a soot that can be more easily removed from the VGT components by preventing or moving the VGT components such as wings. The increase in temperature is a “heating mode” of the type conventionally used to heat, regenerate, or wash a diesel oxidation catalyst (DOC), diesel particulate filter (DPF), or selective catalytic reduction device (SCR). It can be performed using the same equipment and the same techniques conventionally used during operation. Increasing the temperature upstream of the VGT to at least about 175 ° C. has been found to be effective in promoting prevention of varnish deposits, and increasing the temperature to at least about 350 ° C. Has been found to be effective in promoting the removal of varnish deposits in other ways.

  The operating parameters usually consist of one or more parameters indicating the varnish deposition or the potential for varnish deposition, depending on which varnish deposition control sequence is performed. Examples of operating parameters include estimated varnish deposition level, actual varnish deposition level, force required to change VGT nozzle opening diameter, engine operation period, engine idle operation period, ambient temperature, engine coolant temperature Faulty hardware detection, cylinder temperature, intake manifold temperature, and injection pressure. Operating parameters such as the force required to change the nozzle opening diameter of the VGT will represent the effect of varnish deposition and determine whether the operating parameters are at a defined level to initiate the varnish deposition control sequence. The means for determining is an electrical sensor 35 such as an ammeter, voltmeter, or other sensor conventionally used to measure the power drawn by the motor 37 in an attempt to move the VGT wing. It may be. Operating parameters such as engine operating period, engine idle operating period, ambient temperature, and engine coolant temperature are parameters that tend to act as causes or factors related to varnish deposition, and the operating parameters start the varnish deposition control sequence The means for determining whether the level is a predetermined level may be a thermometer or a sensor such as a temperature sensitive switch 39 and a timer 41. Operating parameters, such as actual varnish deposition level, are based on direct observation or measurement, and means for determining whether the operating parameters are at a defined level for initiating the varnish deposition control sequence is the camera 43. It may be a device that enables direct or indirect measurement or observation. Operating parameters, such as estimated varnish deposition levels, can be actual, measured parameters, such as parameters that tend to cause varnish deposition or are related to varnish deposition. Based on a model that calculates varnish deposition as a function, the means for determining whether the operating parameter is at a defined level for initiating the varnish deposition control sequence, determines the level of the actual parameter. Can be any of the means used (e.g., electrical sensors, thermometers, temperature switches, timers, sensors that provide different signals when the sensors are covered with different amounts of varnish, and / or cameras) . Operating parameters such as faulty hardware include parameters that tend to be related to “fuel contamination”, such as faulty fuel injectors and faulty sensors. Operating parameters such as cylinder temperature include a determination that the cylinder is relatively cold, which is a situation that can cause or represent varnish. Operating parameters such as low intake manifold temperature and low injection pressure are also parameters that can cause or represent varnish.

  The controller 29 can be configured to increase the exhaust temperature to the first exhaust temperature by one or more techniques. The control device 29 may, for example, reduce the VGT nozzle opening diameter, delay the fuel injection timing (for example, by controlling the operation of the fuel injection nozzle 45), or (for example, by controlling the operation of the fuel injection pump 47). The exhaust temperature can be increased by lowering the fuel injection pressure, increasing the speed of the engine 23, and injection by a seventh injector 49.

  The varnish deposition control sequence functions for the purpose of reducing or removing the resulting varnish deposition, for the purpose of preventing varnish deposition, or for both reducing or removing varnish deposition and preventing varnish deposition. be able to. The varnish deposition control sequence that will be performed to prevent varnish deposition is to a different extent, a different speed, or a different cycle than the varnish deposition control sequence that will be performed to reduce or eliminate varnish deposition. In relation to the steps of increasing the exhaust temperature upstream of the VGT 27 to a different first exhaust temperature and increasing the exhaust temperature to the first exhaust temperature, the nozzle opening of the VGT nozzle is opened with a small opening diameter and a large opening. Changing between calibers. Thus, under certain circumstances, varnish deposition control sequences aimed at preventing varnish deposition may result in varnish deposition, in which case varnish deposition may be reduced or eliminated. It may be necessary to initiate the intended varnish deposition control sequence.

  As will be described, the determination means such as the electric sensor 35 may constantly monitor the force required to change the opening diameter of the nozzle 33 of the VGT 27. The controller 29 passes the exhaust temperature through a sufficient number of temperature cycles, including maintaining the exhaust temperature at the first exhaust temperature for at least a predetermined amount of time between each cycle. The opening diameter of the nozzle 33 of the VGT 27 is made small so that the force required to change the nozzle opening diameter of the VGT from the low exhaust temperature to the first exhaust temperature or to keep the force required to change the nozzle opening diameter of the VGT below a predetermined value. It can be configured to change a sufficient number of times between the aperture and the large aperture. If the varnish deposition results in the force required to change the nozzle opening diameter of the VGT 27 still exceed a predetermined value, the varnish deposition control sequence can function in a deposition reduction or removal mode. In the deposition reduction or removal mode, the controller 29, after at least a sufficient number of temperature cycles, increases the exhaust temperature to the first exhaust temperature (the first exhaust temperature that has increased the exhaust gas to prevent varnish deposition). Between the first exhaust temperature and the second lower exhaust temperature, or the force required to change the nozzle opening diameter of the VGT changes to a value below a predetermined value. Thus, the nozzle opening of the VGT can be configured to change a sufficient number of times between the small opening diameter and the large opening diameter.

  FIG. 2 is a flowchart showing the basic steps of the method for controlling varnish deposition in the VGT 27 of the diesel engine turbocharger 25. The first step 100 consists of determining whether the operating parameters are at a level set to initiate the varnish deposition control sequence. If the operating parameter is not at a predetermined level (ie, “No”), the operating parameter is continuously or periodically monitored to determine whether the operating parameter has changed and is at a predetermined level (ie, “Yes”). Determine whether or not. The second step 200 comprises the step of starting a varnish deposition control sequence accordingly when it is determined that the operating parameter is at a predetermined level. This sequence is related to the steps of increasing the exhaust temperature upstream of the VGT 27 to the first exhaust temperature and increasing the exhaust temperature to the first exhaust temperature, and the nozzle opening of the VGT nozzle 33 has a small opening diameter. Varying between large aperture diameters.

  The operating parameters usually consist of one or more parameters indicating the varnish deposition or the possibility of varnish deposition, depending on which varnish deposition control sequence is performed, for example, the estimated varnish deposition level, One or more of the actual varnish deposition level, the force required to change the nozzle opening diameter of the VGT, the engine operation period, the engine idle operation period, the ambient temperature, and the engine coolant temperature.

  The method typically includes circulating the exhaust temperature between a first exhaust temperature and a second lower exhaust temperature through a plurality of temperature cycles. The first exhaust temperature is usually the temperature selected for the purpose of preventing varnish deposits (currently considered to be at least about 175 ° C.) or, for example, turning the varnish deposits into pieces. To a temperature selected for the purpose of removing varnish deposits (currently considered to be at least about 350 ° C.). The second low exhaust temperature is usually a particular engine operating mode that is a problem under certain ambient conditions (e.g., engine under high engine load or idle, and / or at high or low ambient temperature and pressure). Exhaust temperature generated by operation). The exhaust temperature is known by equipment conventionally used to perform “heating mode” operations used to heat, regenerate or wash engine exhaust aftertreatment system components, or by raising the exhaust temperature. It can be raised by other techniques that are used.

  During any continuous cycle, the length of time that the temperature is maintained at the first temperature and the length of time that the temperature is maintained at the lower second temperature is determined in a particular operating mode under certain ambient conditions. Depending on factors including the length of time required for effective varnish deposition control at a given engine operation. The effect of any heating cycle on other exhaust systems or engine operation will also typically be considered in selecting the length of time that the temperature is maintained at the first temperature or the second temperature.

  The opening diameter of the nozzle 33 of the VGT 27 is changed between the small opening diameter and the large opening diameter during the temperature cycle or during the temperature rise period after the exhaust gas temperature is circulated through a plurality of temperature cycles. The opening diameter of the nozzle 33 can be circulated between the small opening diameter and the large opening diameter through a plurality of nozzle opening / closing cycles. The opening diameter of the nozzle 33 of the VGT 27 can be varied between 0% and 100% opening diameter (and vice versa, if appropriate), but the opening diameter may be other than the fully closed or fully open. The diameter may be changed.

  A varnish deposition control sequence that has been found to be particularly effective in preventing varnish deposition includes maintaining the opening diameter of the nozzle 33 at a predetermined opening diameter when the engine cooling water temperature is equal to or higher than a predetermined engine cooling water temperature. For example, in certain types of engines, when the coolant temperature is 60 ° C. or higher, the VGT can be left open until the coolant temperature reaches a high temperature (eg, 80 ° C.) to facilitate engine warm-up. . However, especially at low ambient temperatures, if the VGT is open, the cooling water temperature can only be high or can only be reached slowly, and the exhaust temperature is relatively low leading to the formation of varnish deposits. Tend. The present inventor maintains the opening diameter of the nozzle of such a vehicle at an opening diameter of 3.6% of the maximum opening diameter when the cooling water temperature is 60 ° C. or more and less than 80 ° C. to prevent varnish accumulation. We found that promotion is effective. The most effective opening diameter and coolant temperature to prevent varnish buildup are expected to vary with various engine types, operating modes, and ambient operating conditions.

  Other varnish deposition control sequences that have been found to be particularly effective in preventing varnish deposition include operating parameters that include a predetermined ambient temperature at or below ambient temperature and a predetermined length of time that exceeds or exceeds the operating period. Is related. For example, certain engine types of operation at ambient temperatures of -15 ° C for extended periods of time have been found to result in varnish deposition. The inventor has discovered that it is effective to initiate a varnish deposition control sequence to prevent varnish deposition after these low temperature operations after a certain length of time (eg, 4 hours). did. The varnish deposition control sequence can include circulating the exhaust temperature between a first exhaust temperature and a second lower exhaust temperature through a plurality of temperature cycles.

  Another varnish deposition control sequence that has been found to be particularly effective in preventing varnish deposition involves operating parameters including long idle operation of a predetermined length of engine. For example, for some engine types, the inventor can effectively prevent varnish accumulation by starting the varnish deposition control sequence when it is determined that the engine has been idle for an extended period of 30 minutes. I found out that it could be. In contrast, in this same type of engine, as a soot accumulation control strategy, the algorithm automatically starts circulating VGT (without increasing the temperature) after a long idle period of 1 hour.

  The ultimate goal of the varnish deposition control sequence to control the varnish in the VGT is to ensure proper operation of the VGT, particularly the ability of the VGT blades to open and close the nozzles, without being affected by varnish deposition. is there. In certain circumstances, the varnish deposition control sequence typically goes through a sufficient number of temperature cycles to circulate the exhaust temperature between the first exhaust temperature and the second lower exhaust temperature, and the nozzle opening diameter of the VGT. One or both of the steps of changing the nozzle opening of the VGT a sufficient number of times between the small opening diameter and the large opening diameter are included so that the force required to change the pressure is less than a predetermined value. This includes, for example, measuring the required force by means of an electrical sensor 35 and starting the varnish deposition control sequence when the required force rises above the normal level, until the required force returns to the normal level. Repeat heating and / or opening diameter change cycle as part of prevention mode, or start varnish deposition control sequence when required force rises above acceptable level until required force returns to acceptable level Repeating the heating and / or opening diameter change cycle as part of a varnish deposition reduction or removal mode.

  In this application, the use of terms such as “including” is non-limiting and is intended to have the same meaning as terms such as “comprising” and excludes the presence of other structures, materials, or acts. Not what you want. Similarly, the use of terms such as “can be” or “may be” is also non-limiting and is intended to indicate that a structure, material, or act is not essential, Not using such terms does not indicate that a structure, material, or action is essential. If the structure, material, or action is considered currently essential, it will be identified as such.

  While the invention has been illustrated and described in accordance with preferred embodiments, it will be appreciated that variations and modifications can be made to the invention without departing from the invention as set forth in the appended claims.

Claims (20)

A method for controlling varnish deposition in a variable geometry turbine (VGT) of a diesel engine turbocharger, comprising:
Determining whether the operating parameter is at a defined level to initiate a varnish deposition control sequence;
If it is determined that the operating parameter is at a predetermined level, the method comprises the step of starting the varnish deposition control sequence, the sequence comprising:
Increasing the exhaust temperature upstream of the VGT to a first exhaust temperature;
A varnish deposition control method comprising: changing the opening diameter of the VGT nozzle between a small opening diameter and a large opening diameter in association with the step of raising the exhaust temperature to the first exhaust temperature.   The operating parameters are estimated varnish deposition level, actual varnish deposition level, force required to change the nozzle opening diameter of the VGT, engine operation period, engine idle operation period, ambient temperature, engine coolant temperature, The varnish deposition control method of claim 1, comprising one or more of faulty hardware detection, cylinder temperature, intake manifold temperature, and injection pressure.   The varnish deposition control method according to claim 1 or 2, comprising a step of circulating the exhaust temperature between the first exhaust temperature and a second low exhaust temperature through a plurality of temperature cycles.   4. The method according to claim 1, further comprising a step of changing the opening diameter of the VGT nozzle between the small opening diameter and the large opening diameter after the exhaust temperature circulating step through the plurality of temperature cycles. The varnish deposition control method as described.   Changing the opening diameter of the VGT nozzle between the small opening diameter and the large opening diameter by circulating the nozzle between the small opening diameter and the large opening diameter through a plurality of nozzle opening / closing cycles. The varnish deposition control method according to any one of claims 1 to 4.   The varnish deposition control method according to any one of claims 1 to 5, wherein the first exhaust temperature is a temperature sufficient to change the varnish accumulated in the VGT into a splinter.   The varnish deposition control method according to claim 1, wherein the first exhaust temperature is about 175 ° C. or higher.   The varnish deposition control method according to claim 1, wherein the first exhaust temperature is about 350 ° C. or higher.   The varnish deposition control method according to any one of claims 1 to 8, comprising a step of maintaining the exhaust temperature at the first exhaust temperature for a predetermined length of time.   The varnish deposition control method according to any one of claims 1 to 9, comprising a step of changing the opening diameter of the VGT between an opening diameter of 0% and 100%.   The varnish deposition control method according to any one of claims 1 to 10, comprising a step of maintaining the opening diameter of the VGT nozzle at a predetermined opening diameter when the engine cooling water temperature is equal to or higher than a predetermined engine cooling water temperature.   The operating parameters include a predetermined ambient temperature at or below ambient temperature and a predetermined length of time that exceeds or exceeds the operating period, and the varnish deposition control sequence undergoes a plurality of temperature cycles through the exhaust temperature. The varnish deposition control method according to any one of claims 1 to 11, further comprising the step of circulating between the first exhaust temperature and the second low exhaust temperature.   The operating parameter includes long idle operation of the engine, and the varnish deposition control sequence is initiated when it is determined that the engine has been idle for a long time for a predetermined length of time. The varnish deposition control method according to any one of 1 to 12.   Increasing the exhaust temperature to the first exhaust temperature by one or more of reducing the VGT nozzle opening diameter, delaying injection timing, decreasing fuel injection pressure, increasing engine speed, and injection by a seventh injector. The varnish deposition control method according to any one of claims 1 to 13.   Circulating the exhaust temperature between the first exhaust temperature and the second lower exhaust temperature through a sufficient number of temperature cycles; and a force required to change the opening diameter of the VGT is a predetermined value. The varnish deposition control method according to claim 1, comprising one or both of steps of changing the opening diameter of the VGT nozzle a sufficient number of times between the small opening diameter and the large opening diameter so as to be equal to or less than a value. . A diesel engine device,
A diesel engine,
A turbocharger including a variable form turbine (VGT) downstream of the engine;
Means for determining whether the operating parameter is at a defined level for initiating a varnish deposition control sequence to control varnish deposition on the VGT;
When the determination means determines that the operating parameter is at a predetermined level, the control unit is configured to start the varnish deposition control sequence, the varnish deposition control sequence,
Increasing the exhaust temperature upstream of the VGT to a first exhaust temperature;
A diesel engine device comprising a step of changing the opening diameter of the VGT nozzle between a small opening diameter and a large opening diameter in association with the step of raising the exhaust temperature to the first exhaust temperature.   The operating parameters include estimated varnish deposition level, actual varnish deposition level, force required to change the VGT nozzle opening diameter, engine operation period, engine idle operation period, ambient temperature, and engine coolant temperature. The diesel engine device of claim 16, comprising one or more of:   The control device may reduce the exhaust temperature to the first exhaust temperature by one or more of a decrease in VGT nozzle opening diameter, a delay in injection timing, a decrease in fuel injection pressure, an increase in engine speed, and injection by a seventh injector. 18. A diesel engine device according to claim 16 or 17 configured to be raised.   The determination means determines whether or not a force necessary to change the opening diameter of the VGT nozzle exceeds a predetermined value, and the control device determines the exhaust temperature through at least a sufficient number of temperature cycles. The force required to circulate between the first exhaust temperature and the second lower exhaust temperature or to change the opening diameter of the VGT nozzle is changed to a value equal to or less than the predetermined value. The diesel engine device according to any one of claims 16 to 18, further configured to change the opening diameter of the VGT nozzle between the small opening diameter and the large opening diameter.   The control device increases the exhaust temperature from the second low exhaust temperature to the first exhaust temperature through at least a sufficient number of temperature cycles, or changes the opening diameter of the VGT nozzle. The opening diameter of the VGT nozzle is configured to be changed a sufficient number of times between the small opening diameter and the large opening diameter so as to maintain a force required for the rotation below a predetermined value. The diesel engine apparatus in any one.

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