JP4237350B2 - Lean combustion control method of gas engine in gas filling device - Google Patents

Description

【００９３】
この第２マップでは、スロットル開度が低い領域で運転性を優先させ（Ａ領域）、中間開度では排気ガス（ＮＯｘ）低減を優先（Ｂ領域）あるいは運転効率を優先させ（Ｄ領域）、高開度では出力確保を優先させている（Ｃ領域）。
【００９４】
図１０（Ａ）（Ｂ）は、気筒判別用波形および失火判別用波形のデータ例を示すグラフである。
図１０（Ａ）に示すように、カム軸の回転を検出するパルサーコイルからのパルサー信号ａがクランク軸の２回転（７２０度）ごとに入力される。このパルサー信号ａに同期してクランク角センサからのクランク角パルス信号ｂが入力される。このクランク角信号は、例えば１２０枚の歯を有するリングギヤの各歯を検出するごとに出力されるものであり、パルサー信号が得られる２回転では２４０個のパルス信号となり、クランク角３度ごとに１個のパルスが入力される。このパルサー信号の検出位置を例えば＃１気筒のＢＴＤＣ９０度に設定しておく。これにより、例えば＃１→＃３→＃４→＃２の順で点火される４気筒エンジンで、例えば９０度ごとに排圧が検出される４気筒の各々についてパルサー信号の検出位置からのクランク角度により気筒番号が判別される。
【００９５】
各気筒の燃焼条件はそれぞれ微妙に異なるため各気筒の排圧波形も異なる。本発明では、このように気筒を判別して気筒ごとに失火を判定することにより、各気筒の排圧波形に対応してそれぞれ最適なフィードバック制御が可能になる。
【００９６】
図１０（Ｂ）は４気筒の排圧検出データである。実線のグラフｃが正常時の排圧波形であり、点線のグラフｄが失火時の排圧波形である。このような波形検出データから、各気筒のごとに波形の面積を算出し、この波形面積に基づいて失火を判別する。この場合、各気筒の波形データにおいて、圧縮上死点後の積算開始クランク角ｔ１と積算終了クランク角ｔ２を設定しておく。
【００９７】
所定のクランク角で所定気筒に点火され、爆発、排気行程を経て排気管途中の排圧センサ部に排気ガスが到達する。この排気ガス到達までのクランク角（エンジン速度により異なる）を考慮して排圧波形のピークを挟んで排圧データを取込めるように、気筒ごとの点火タイミングに対応して気筒別にｔ１およびｔ２を定めておく。
【００９８】
各気筒ごとにクランク角ｔ１〜ｔ２間の波形面積を算出して、これと直前の所定サイクルの移動平均値と比較する。この波形面積の平均値に対する比率Ｒをマップに格納された基準値と比較して失火を判別する。この基準値は、運転領域に対応したマップの座標ごとに異なる。
【００９９】
図１１は、失火判定の基準値のマップを示す立体図である。
図示したように、スロットル開度とエンジン回転数に応じたマップ座標位置により、失火判定基準（％）を異ならせている。この例では高回転でスロットル高開度側では失火判定基準が低く、低回転低スロットル開度側では基準が高い。したがって、高回転高負荷側では、前述の排圧波形面積が平均値に比べ大きく減少して例えば２０００ｒｐｍ以上の高負荷領域では前記比率Ｒが２０％以下まで小さくならないと失火と判定されず、リーン化が続行される。これに対し、低回転低負荷側では、排圧波形面積の比率Ｒが３０〜４０％になると失火と判定されリーン化が停止される。
【０１００】
このように、失火判定基準を運転領域に応じて変えることにより、前述の第２マップを運転領域ごとに所望の優先特性に応じて形成したことと相まって、運転領域全体にわたって最適な運転状態が得られる。
【０１０１】
なお、排圧波形面積の平均値に対する比Ｒを求めてこれを基準値と比較する方法に代えて、排圧波形面積と平均値との差を求めてこの差を予め定めた所定の基準値（この基準値も運転領域に応じて異なる）と比較することにより失火を判定してもよい。
【０１０２】
本実施の形態においては、燃料制御弁２９を経た燃料ガスがミキサー２４内で空気と混合され、混合器がミキサー２４内で流量調整されたのち、エンジン４に吸引される。このため、燃料制御弁２９による燃料ガス量の調整により空燃比が制御される。このため多気筒エンジンの場合、気筒別失火判定の結果の失火気筒の失火回復は、空燃比制御に加え個別気筒毎の点火時期制御を組み合わせることにより、有効に達成可能である。
【０１０３】
また、吸気マニホールドの各気筒への分配管にそれぞれミキサーを配置し、このそれぞれのミキサーに別個の燃料制御弁を介して燃料ガスを導くようにし、吸気マニホールドの内分配管の上流部に吸入空気量を制御するスロットル弁を配置する場合には、気筒別失火判定の結果の失火気筒の失火回復は、失火気筒に対応する燃料制御弁の開度を大きくする方向に微調整することにより達成可能である。この場合さらに個別気筒毎の点火時期制御を組み合わせてもよい。
【０１０４】
【発明の効果】
以上説明したように、本発明では、圧縮機吐出側のガスタンクの圧力に応じて、ガスエンジンまたは圧縮機の回転数が制御されるため、圧力に応じた最適効率でガスエンジンの出力制御を行うことができる。
【０１０５】
また、希薄燃焼制御のベースマップとして、例えば予め分っている失火が起きない燃料供給量データを設定するとともに、このベースマップよりリーン側に設定した第２マップを備え、ベースマップによる燃料供給量から失火するまで燃料を徐々にリーン化し、失火した時点の燃料供給量または失火する前に第２マップに達した場合には、その第２マップの燃料供給量にベースマップが書き換えられる。これにより失火限界と第２マップの組合せによるマップが学習により形成され、失火限界のマップに対し予め設定した所望特性が得られる第２マップを加味して燃料制御マップを形成することができる。このような失火学習制御により、エンジン負荷やエンジン回転数の急激な変化に素速く追従できるとともに、運転状態に応じた最適な希薄燃焼が達成され、有効なＮＯｘの低減および燃費の改善が図られる。
【０１０６】
この場合、第２マップとして、エンジン回転数とスロットル開度に応じたマップ形成領域ごとに異なる運転特性を優先させて、その運転特性が得られる最もリーン側の燃料供給量となるように設定すれば、この第２マップに、エンジン回転数とスロットル開度に応じた運転領域ごとにその領域で要求される運転特性に合った燃料供給量データが設定されるため、失火限界の範囲内で運転領域に応じた最適な運転特性で燃料制御が行われる。
【図面の簡単な説明】
【図１】 本発明が適用されるガス充填装置の構成図。
【図２】 図１のガス充填装置の充填圧力とエンジン回転数の関係のグラフ。
【図３】 図１のガス充填装置の制御系の構成図。
【図４】 本発明の実施の形態に係る燃料制御弁の動作制御プログラムのフローチャート。
【図５】 本発明の燃料制御方法のメインプログラムのフローチャート。
【図６】 図５のフローチャートにおける学習プログラムのフローチャート。
【図７】 図６のフローチャートにおける書換プログラムのフローチャート。
【図８】 本発明の失火判定プログラムのフローチャート。
【図９】 エンジンの運転領域のグラフ。
【図１０】 気筒判別及び失火判定のための波形データのグラフ。
【図１１】 失火判定基準のマップを示す立体図。
【符号の説明】
１：ガス充填装置、２：ガス吸入口、３：ケーシング、４：エンジン、
５：圧縮機、６：ガス冷却器、８：排気口、１０：主換気ファン、
１３：クランク軸、２１：エアクリーナ、２３：スロットル弁、
２４：ミキサー、２５：スロットル弁開閉駆動モータ、
２６：燃料ガス供給用配管、２８：減圧調整弁、
２９：燃料ガス流量制御弁（燃料制御弁）、３４：ラジエータ、
３５：冷却水ポンプ、４２：圧縮機出口管、４３：ガス供給元弁、
４４：全ガス流量計、４５：逆止弁、４６：除湿装置、
４８：第１の圧力センサ、５１：充填カプラソケット、
５２：充填ホース接続確認用センサ、５４：オイルフィルター、
５５：第２の圧力センサ、５６：ブローダウン弁、
５７：ブローダウンタンク、５８：リリーフ弁、５９：放出口、
６１：加熱装置、６３：空気加熱用パイプ、６４：吸引用パイプ、
６５：エアクリーナ、７１：制御装置、７２：運転切換えスイッチ、
７３：第１の温度センサ、７４：第２の温度センサ、
７５：第３の温度センサ、７６：第４の温度センサ、
７７：第５の温度センサ、７８：ガス洩れ検知器、
８０：スロットル弁開度センサ、８２：メモリ、１１０：一方向クラッチ、
１１１：ファン駆動軸、１１２：変速装置、１１３：回転機、
１１４：プーリ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas filling device for filling a gas tank of a gas tank such as a vehicle or various devices using gas fuel, and more particularly, to a lean combustion control method for leaning fuel while judging misfire of the gas engine. It is.
[0002]
[Prior art]
As a gas filling device, a gas filling device comprising a compressor that compresses fuel gas and a gas engine that drives the compressor has been developed. In this gas filling device, the gas inlet of the compressor is connected to a fuel gas supply source, the gas outlet is connected to a gas tank of a vehicle or various devices by a filling hose, and the compressor is driven by the gas engine. Then, the fuel gas is pressurized to a predetermined high pressure and filled in a gas tank of a vehicle or the like.
[0003]
[Problems to be solved by the invention]
However, in the conventional gas filling device, the filling pressure increases at the end of filling, the amount of gas (filling flow rate) filled from the compressor to the gas tank of the vehicle decreases, and it takes a long filling time. There was a problem.
[0004]
On the other hand, in a gas engine of such a gas filling device, it is conceivable to drive the engine by a lean combustion method in order to reduce NOx and improve fuel consumption. In this case, for example, when lean combustion control is performed using a misfire limit base map set according to the engine speed and throttle opening, if misfire occurs and this is not dealt with, the next time Misfire occurs again in the operation region, and as a result, unburned gas is discharged and fuel consumption is also deteriorated.
[0005]
A lean combustion control method for a gas engine used in the field of general vehicles and air conditioning systems is disclosed in Japanese Patent Laid-Open No. 10-131895. The publicly known technology described in this publication is provided with a map of the opening data of the gas flow control valve, and is intended to maintain a lean combustion state close to the misfire limit by rewriting the map to the lean side within a range that does not misfire by the learning step. is there. Such lean combustion improves the fuel consumption and measures for NOx exhaust gas.
[0006]
On the other hand, when the engine is operated, various operating characteristics such as engine output, combustion efficiency or drivability, as well as fuel efficiency and exhaust gas countermeasures, depending on the operating range according to the engine speed and throttle valve opening, for each region. The best operating characteristics for that area are required.
[0007]
However, in the fuel control method described in the above publication, since the map data is rewritten to a value close to the misfire limit for the entire operation region, the final map data after learning is almost the entire misfire limit regardless of the operation region. This is the fuel control valve opening. For this reason, fuel is always maximized when it is desired to obtain the best operating condition for each region in preference to lean combustion, especially in high-load operation regions where it is desired to secure output and where combustion efficiency is desired. Since the fuel is diluted near the misfire limit, desired operation characteristics cannot be obtained, and a combustion state having optimum operation characteristics required according to the operation region cannot be obtained.
[0008]
The present invention takes the above-mentioned conventional technology into consideration, and enhances gas filling efficiency, which is a problem specific to the gas filling device, to shorten the filling time, and performs sufficient lean combustion to sufficiently reduce NOx and fuel consumption. In addition, an object of the present invention is to provide a lean combustion control method in a gas filling device that can achieve optimum operation characteristics for each region according to the operation region.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in a lean combustion control method for a gas engine in a gas filling machine comprising a compressor for compressing a fuel gas and filling a gas tank, and a gas engine for driving the compressor. The gas pressure sent from the compressor to the gas tank is detected, and based on this, the rotational speed of the gas engine or the compressor is controlled, and a map based on a preset engine rotational speed and throttle opening is used. The map has a base map and a second map in which the fuel supply amount is set to a leaner side than the base map. During the fuel supply controlled by the base map, the fuel is gradually increased while determining misfire. Leaning, when misfiring or when reaching the second map, stop leaning and learn the fuel supply amount and rewrite the base map Providing lean burn control method for a gas engine in the gas filling device and controls the fuel supply amount in accordance with the rewritten basemap.
[0010]
According to this configuration, since the rotation speed of the gas engine or the compressor is controlled according to the pressure of the gas tank on the discharge side of the compressor, the output control of the gas engine can be performed with the optimum efficiency according to the pressure. As the rotation speed control in this case, for example, the rotation speed of the compressor is gradually decreased as the gas pressure in the gas tank increases, or the engine rotation speed is increased when the pressure at the initial stage of charging is low, and rapid filling is performed. You may control so that it may aim.
[0011]
In addition, as a base map for lean combustion control, for example, fuel supply amount data that does not cause misfire, which is known in advance, is set, and a second map that is set leaner than the base map is provided. The fuel is gradually leaned until the misfire, and the base map is rewritten with the fuel supply amount at the time of misfire or when the second map is reached before the misfire. As a result, a map based on the combination of the misfire limit and the second map is formed by learning, and the fuel control map can be formed by taking into account the second map that provides the preset desired characteristics with respect to the misfire limit map. In this case, a rewrite map is provided in addition to the base map, and the rewrite map can be rewritten in order to perform learning by rewriting the base map substantially while leaving the original base map.
[0012]
In a preferred configuration example, the second map is the leanest fuel supply amount that gives priority to different operating characteristics for each map formation region corresponding to the engine speed and the throttle opening, and obtains the operating characteristics. It is characterized by being set as follows.
[0013]
According to this configuration, since the fuel supply amount data that matches the operation characteristics required in each operation region corresponding to the engine speed and the throttle opening is set in the second map, the misfire limit range The fuel control is performed with the optimum operation characteristics corresponding to the operation region.
[0014]
In a more preferable configuration example, when the base map is rewritten, the same offset amount is rewritten in a richer range than the second map in other areas as well as the controlled area.
[0015]
According to this configuration, while learning the fuel control in a certain area, the base map is rewritten uniformly in the other areas by the offset amount to the same lean side, so that the learning operation is performed efficiently.
[0016]
In a further preferred configuration example, when the misfire is determined, leaning is performed step by step, and when misfire is detected, the rich map is returned to the rich side by a predetermined step within a range on the lean side from the base map.
[0017]
According to this configuration, the lean fuel can be made closer to the misfire limit while maintaining the set amount of the leanest base map in which it is guaranteed that misfire does not occur in advance.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of a gas filling device according to an embodiment of the present invention. FIG. 2 is a graph showing the relationship between the charging pressure and the rotational speed of the main ventilation fan.
[0019]
The gas filling device 1 of this embodiment compresses, for example, natural gas (hereinafter simply referred to as gas) supplied from a gas inlet indicated by reference numeral 2 in FIG. In order to fill, a single casing 3 accommodates an engine 4, a compressor 5, a gas cooler 6 and the like which will be described later.
[0020]
The gas cooler 6 of the gas filling device 1 according to this embodiment employs a water-cooled type. The heat exchanger 6a of the gas cooler 6 is interposed on the downstream side of the radiator in the engine cooling water system, and adopts a structure for cooling the gas with the engine cooling water cooled by the radiator 34. In this embodiment, the radiator 34 is disposed at the exhaust port 8 of the casing 3. The cooling water pump 35 is of a structure that is driven by the engine 4.
[0021]
According to the gas filling device 1 configured as described above, the gas can be cooled by using the engine cooling water of the water-cooled engine 4, so that the gas cooler is compared with a case where an air-cooled gas cooler is used. The freedom degree of the position which arrange | positions 6 in the casing 3 can be increased. For this reason, the gas cooler 6 can be arranged in a dead space formed in the casing 3.
[0022]
A pulley for driving the cooling water pump 35 is connected to the crankshaft 13 and a fan drive shaft 111 is connected to the end of the crankshaft via a one-way clutch 110. The fan drive shaft 111 has a variable fan speed relative to the engine speed. And a pulley 114 that is belt-connected to a rotating machine 113 that also serves as a generator and an electric motor. During the operation of the engine 4, part of the engine power is transmitted to the transmission 112 and the pulley 114 via the one-way clutch 110, and the rotating machine 113 functions as a generator and the transmission 112 matches the required cooling performance. The main ventilation fan 10 is driven at the selected gear ratio.
[0023]
At the time of ventilation operation while the engine 4 is stopped, for example, when the gas leak detector 78 detects gas, the rotating machine 113 receives power supply from a battery (not shown) and functions as an electric motor via the transmission 112. The ventilation fan 10 is driven. At this time, the rotational force of the electric motor is not transmitted to the crankshaft 13 side with a large load by the one-way clutch 110.
[0024]
In order to increase the cooling performance of the water-cooled gas cooler 6, the transmission 112 is controlled so that the rotational speed of the main ventilation fan 10 is higher than the engine rotational speed to increase the heat radiation amount of the radiator 34. Do. By improving the cooling performance of the gas cooler 6 in this way, the temperature rise of the gas is mitigated at the end of gas filling, and the density of the gas discharged from the compressor 5 can be kept high.
[0025]
This is shown in FIG. The compressor 5 increases the pressure of the substantially constant gas supply source detected by the first pressure sensor 48 to the discharge pressure detected by the second pressure sensor 55. That is, as the filling proceeds, the total compression ratio increases and the calorific value increases, but as the discharge pressure, that is, the filling pressure increases, the rotational speed of the main ventilation fan increases, and the filling efficiency decreases. Is preventing.
[0026]
In FIG. 1, what is shown by the code | symbol 91 interposed in the engine cooling water system is a thermostat valve. The reference numeral 92 connected in the vicinity of the coolant outlet of the gas cooler 6 is a coolant reserve tank.
In the dehumidifying device 46 of the gas filling device 1 according to this embodiment, the heat source of the heating device 61 is engine cooling water that has absorbed the waste heat of the engine 4. More specifically, a heat exchanger 93 having a structure in which the air heating pipe 63 of the dehumidifying device 46 is heated with relatively high-temperature engine cooling water is interposed between the engine outlet and the radiator inlet. is doing.
[0027]
In this embodiment, the compression parts # 2 to # 4 of the compressor 5 and the compressor outlet rod 42 are communicated with the blowdown tank 57 via the safety valve 94, respectively. Further, an emergency separation coupler 95 is interposed on the upstream side of the filling coupler socket 51.
The compressor 5 employs a structure in which oil is pumped to the mechanical portion of the compression section # 4 where the load is greatest. The oil pump is indicated by reference numeral 96, the oil filter is indicated by reference numeral 97, and the oil pressure regulating valve is indicated by reference numeral 98.
[0028]
What are indicated by reference numerals 120 and 121 are oil drain valves that are simultaneously opened when the blow-down valve 96 is opened and circulate the oil captured by the oil filter 54 to the blow-down tank 57.
[0029]
Reference numeral 21 denotes an air cleaner, 23 denotes a throttle valve, 24 denotes a mixer, 25 denotes a throttle valve opening / closing drive motor, and 26 denotes a fuel gas supply pipe. On the fuel gas supply pipe 26, there are provided a pressure reducing adjustment valve 28 and a fuel gas flow rate control valve 29 for controlling the pressure of the fuel gas supplied to the engine 4 to be reduced to substantially atmospheric pressure. Reference numeral 43 is a gas supply source valve, 44 is a total gas flow meter, and 45 is a check valve.
[0030]
The compressor outlet pipe 42 passes through the casing 3 and is led out of the casing 3, and a filling coupler socket 51 is connected to the tip portion. By connecting the filling coupler socket 51 to a tank-side coupler socket of a vehicle (not shown), the compressor 5 is communicated with a gas tank of the vehicle. The filling coupler socket 51 includes a filling hose connection confirmation sensor 52 that detects that the tank side coupler socket is connected.
[0031]
The blow-down tank 57 is used to reduce the pressure of the gas filling system by discharging the gas remaining in the compression system at the start of filling and before connecting the filling coupler socket 51 to the vehicle. That is, by opening the blow-down valve 56 and reducing the residual pressure in the compressor 5, the filling coupler socket 51 can be easily connected to the tank side coupler socket manually. When the blow-down valve 56 is opened, if the pressure in the blow-down tank 57 becomes abnormally high, the relief valve 58 is opened and gas is released from the discharge port 59 to the outside. In addition, since the pressure abnormality can be prevented by taking a sufficient volume of the blowdown tank 57, the relief valve 58 and the discharge port 59 can be omitted in that case.
[0032]
The heating device 61 includes a suction pipe 64 having a downstream end connected to an intake passage on the downstream side of the throttle valve 23. An air cleaner 65 is provided at the upstream end of the air heating pipe 63 and takes in the air in the casing 3.
[0033]
Reference numeral 71 denotes a control device. As shown in FIG. 3, the control device 71 is connected to various sensors on the input side, and is connected to an actuator such as a valve or a motor on the output side to control driving of electronic components and the like.
[0034]
The sensors on the input side include a first pressure sensor 48 for detecting the pressure of the supply gas, a second pressure sensor 55 for detecting the filling pressure, and an operation switching switch 72 for switching the operation mode (see FIG. 1). A suction flow meter 44, a discharge flow meter, a first temperature sensor 73 for detecting the outside air temperature, a second temperature sensor 74 for detecting the temperature in the casing 3, and engine cooling water A third temperature sensor 75 for detecting the temperature at the engine outlet, a fourth temperature sensor 76 for detecting the temperature of the compressor 5, and a temperature of gas discharged from the compressor 5 A fifth temperature sensor 77, a gas detector 78 disposed in the upper part of the casing 3, an engine speed sensor, a throttle valve opening sensor 80, and a filling hose connection confirmation sensor 52. and For example, an exhaust pressure sensor.
[0035]
The output-side actuator includes an ignition control circuit for controlling the ignition timing of the engine 4, a throttle valve opening / closing drive motor 25, a fuel control valve 29, a relief valve 58, a blow-down valve 56, and an intake cutoff valve. , A three-way valve for the dehumidifying device, a rotating machine 113 connected to the main ventilation fan 10, an electromagnetic clutch interposed between the engine 4 and the compressor 5, a cooling water pump 35, and a linear three-way for cooling water valve And a gas supply source valve 43 and an electric motor for driving the auxiliary ventilation fan. Note that some sensors and actuators in FIG. 3 are not shown in FIG. 1, and some sensors and actuators are not provided in the gas filling device in FIG. The power source of the control device 71 and each electronic component is a battery (not shown) so that the actuator can be driven to perform various controls even when the engine 4 is stopped. The battery is charged by the generator while the engine 4 is operating.
[0036]
In addition, the control device 71 has a configuration in which the operation mode of the engine 4 is switched by the operation changeover switch 72. The operation modes are (1) operation stop mode, (2) low-speed filling mode, (3) normal filling mode, and (4) rapid filling mode. At the time of gas filling, the difference between the target engine speed R1 determined for each operation mode and the actual engine speed R2 is obtained, and the throttle valve opening is controlled by feedback control so that the difference in the engine speed is eliminated. . The target engine speed is stored in a memory denoted by reference numeral 82 in FIG.
[0037]
Further, the control device 71 can drive the engine speed to a predetermined speed (the compressor 5) as the difference between the actual gas filling pressure and the predetermined final filling pressure (target pressure) decreases. It is configured to gradually decrease to the minimum speed). In order to decrease the engine speed, the throttle valve opening is decreased with a predetermined function. As this function, a fuzzy function can be used in addition to the proportional function.
[0038]
FIG. 4 is a flowchart of the drive control program for the fuel control valve in the gas filling apparatus according to the embodiment of the present invention.
In this example, a pressure sensor is provided in the exhaust path, a misfire is detected based on the exhaust pressure detected by the pressure sensor, and feedback control is performed to control the fuel control valve according to the presence or absence of misfire. In such control, if the engine load and the engine speed change rapidly, the feedback control cannot follow the engine change, and exhaust emission and fuel consumption deteriorate.
[0039]
In order to cope with this problem, in the present embodiment, a learning step of storing in a memory a control amount of the fuel control valve corresponding to a detected value of at least one of the engine load and the engine speed when the lean combustion state is achieved by feedback control. From then on, by executing the learning steps stored in this memory, the wait time due to feedback is eliminated, and rapid changes in engine load and engine speed are followed quickly, so that exhaust gas emissions and fuel consumption are reduced. Can be improved.
[0040]
The operation in the flowchart of FIG. 4 is as follows.
Step S101: It is determined whether the engine is operating or stopped.
[0041]
Step S102: A fuel control valve opening calculation and setting operation program is executed. The fuel control valve opening is calculated on the basis of the engine speed and the throttle opening at this time, and the stepping motor is driven based on this, and the opening of the fuel control valve is set to the calculated value.
[0042]
Step S103: A misfire control program is executed when the difference between the engine speed and the target engine speed becomes equal to or less than a predetermined value after the engine is started. In this misfire control program, the following processing is executed.
[0043]
(1) Decrease the fuel control valve by a predetermined minute amount from the detected value.
[0044]
(2) The presence or absence of misfire is determined based on the exhaust pipe pressure detected by the exhaust pressure sensor.
[0045]
(3) If there is no misfire, the process of (1) is continued, and if there is a misfire, proceed to the next (4).
[0046]
(4) Increase the fuel control valve by another predetermined minute amount.
[0047]
(5) After the minute amount of fuel is increased, the presence or absence of misfire is determined based on the exhaust pipe pressure detected by the exhaust pressure sensor.
[0048]
(6) If there is a misfire, continue the process of (4) and increase the fuel by a minute amount. If there is no misfire, the process proceeds to the next step S104, and the data map of the fuel control valve opening is rewritten.
[0049]
Step S104: This step is executed under the following conditions.
[0050]
(A) The data map uses the engine speed and the throttle opening as axes.
[0051]
(B) Fuel control valve opening data capable of predetermined lean combustion is set in advance for all component data on the matrix at the time of factory shipment.
[0052]
(C) Similarly, it has a flag map for data management (the same size as the data map and the initial value is 0).
[0053]
The operation in this step is subsequent to the above item (6).
[0054]
(7) The fuel control valve opening data map data is rewritten to the opening data of (4). At this time, the difference S between the opening degree data before the rewriting and the rewriting value is calculated and stored in the memory.
[0055]
(8) The flag corresponding to the data map rewritten in (7) is set to 1 on the flag map. Thereafter, when the flag map is 1, the corresponding data on the data map is not rewritten.
[0056]
{Circle around (9)} The data on the data map corresponding to the point where the flag is 0 is rewritten to a value obtained by uniformly subtracting S. Here, when the value of S is negative, the fuel control valve opening increases. Therefore, even when the misfire is immediately caused by setting the opening degree data deducted by S uniformly by the operations (3) to (6), it is possible to return to the opening range where no misfire occurs. .
[0057]
FIG. 5 is a flowchart of the main program of the fuel control valve feedback control method in the gas engine of the gas filling device according to the embodiment of the present invention.
When the operation is started, first, initial setting of each valve and actuator is performed (step S1). It is determined whether or not the engine has started (step S2). When the start is completed, the target engine speed is calculated (step S3).
[0058]
Subsequently, a misfire determination program is executed (step S4). This is a misfire monitoring program that is always performed during engine operation, apart from misfire control by fuel control valve feedback control, which will be described later.
[0059]
Next, the throttle opening for obtaining the target engine speed calculated in step S3 is calculated, and the throttle valve 23 (FIG. 1) is feedback-controlled (step S5). Next, whether or not feedback control of the fuel control valve 29 (FIG. 1) described later according to the present invention is being performed is determined based on the presence or absence of a feedback control flag (step S6). If not, the opening degree of the fuel control valve is calculated on the basis of a map (base map described later) and set as a target value for feedback control (step S7).
[0060]
Next, a misfire control program for rewriting the base map by learning is performed as described later (step S8). When the misfire determination is completed, it is determined whether or not there is an engine stop command (step S9). If the engine is not stopped, the routine from step S2 is repeated. If the engine is stopped, the devices are stopped in a predetermined order. The engine stop program to be executed is executed (step S10).
[0061]
FIG. 6 is a flowchart of the fuel control valve feedback control for diluting the fuel for the NOx countermeasure by the learning program.
When a subroutine called from the main routine every unit time is started, first, the current position in the map and the surface-complemented value are calculated from the detected data of the throttle valve opening and the engine speed (step S11). At this time, the calculation is performed using both the base map of the fuel control valve and the rewritten map by learning. This value is compared with the value of the previous cycle (step S12). If the difference is larger than the predetermined value, the FB execution flag is turned off and both timer A and timer B described later are turned off without performing fine step-by-step lean control by feedback (FB) control described later (step S22). .
[0062]
If the difference is less than or equal to a predetermined value, it is determined whether or not to execute the FB control from the detection data of the cooling water temperature and the operating state (step S13). For example, if the engine is warming up, the FB control is not executed. Next, it is checked whether the FB control is actually started (step S14). If not started, a one-step lean operation is immediately performed to establish an execution flag. If the FB is being executed, it is determined whether or not the lean operation is currently being performed (step S15).
[0063]
If the lean operation is not in progress, it is determined that a later-described stabilization waiting time is in progress, and the process proceeds to step S23 to determine whether or not the stabilization time has expired based on whether or not a later-described timer B set time has been reached. If the timer set time has not been reached, the routine is repeated until it reaches. When the timer set time is reached and the stabilization time is over, map rewriting processing is performed (step S24).
[0064]
When the lean operation is being performed in step S15, a misfire determination program is executed (step S16). In this misfire determination program, misfire is detected (step S17). This misfire determination is performed, for example, by analyzing a detection waveform from an engine exhaust pressure sensor.
[0065]
If no misfire is detected, it is checked whether the lean time has elapsed (step S18). This lean time check is judged by whether or not the set time of the timer A set in the subsequent lean process (step S19) has been reached. When the lean time has elapsed, the fuel control valve is set to one step lean (step S19). At the same time, the timer A is set to a predetermined lean time. Subsequently, an FB execution flag is set to indicate that the FB is being executed (step S20).
[0066]
Next, it is checked whether the number of steps after leaning is greater than the value of the second map (whether it is leaner than the second map) (step S21). If so, the routine is repeated and the fuel control valve is gradually leaned one step at a time. When the value of the second map is reached without leaning by one step and misfiring, a stabilization time process is performed (step S27). In this stabilization time process, the timer B is set to a predetermined stabilization time and the stabilization process starts.
[0067]
When this stabilization time is over, it is determined that the stabilization time is awaited in step S15, and after the set time by the timer B is over, the value of the base map is rewritten with the value of the second map that has been confirmed not to misfire.
[0068]
On the other hand, if a misfire is detected in the middle of leaning step by step, in step S17 described above, the enrichment operation is immediately performed and the fuel is enriched by a predetermined N steps. This is to recover misfire. This enrichment amount is calculated based on the enrichment map (step S25). After calculating the enrichment amount, it is determined whether the value is below the base map (lean side) (step S26). If it is larger than the base map, the current FB control is invalidated and the FB execution flag is lowered (step S28). This is to avoid rewriting to the rich side of the base map that is known not to misfire.
[0069]
Subsequently, the gas flow control valve opening value corresponding to the map value is returned to the base map value, and a permanent flag is set to the map value (step S29). As a result, when the control is performed in the driving state at this map position thereafter, the fuel control is immediately performed based on the original base map in which the permanent flag is set without performing rewriting by learning for leaning.
[0070]
If the calculated value is equal to or less than the base map in step S26, the stabilization time is set and the stable control mode is entered (step S27). This stabilization time is held for a predetermined time by starting the timer B. When the stabilization time ends, this is determined in step S23 described above, and the base map is rewritten with a misfire value (or a value on the rich side by N steps from the misfire value).
[0071]
In this rewriting process, not only the map position but the entire map area is rewritten by the number of steps lower than the base map at the map position being controlled. In this case, when the second map is reached when the number of rewriting steps is lowered to the lean side at another position, the value is rewritten to the value of the second map without being lowered below the second map at that position.
[0072]
Further, the original base map is stored as it is, and a rewrite map is prepared, and learned values are sequentially written in the rewrite map and used as a new base map.
[0073]
FIG. 7 is a flowchart of the map rewriting process. This is the flow of the map rewriting step S24 of FIG.
First, as in step S11 of FIG. 6 described above, the current map position is calculated from the engine speed and the throttle opening (step S30). A permanent flag is set at the current position (step S31). Next, the current fuel control valve opening is subtracted from the base map calculation value, and the value is set as an offset value (step S32).
[0074]
In step S33, when the entire rewrite map is rewritten, a rewrite counter is prepared and this counter is cleared. The map coordinates in this counter are (x, y), and are initialized to (0, 0) in this process.
[0075]
In step S34, it is checked whether a permanent flag is set in the rewrite map of (x, y) coordinates. If there is a permanent flag, the data at this coordinate position is not rewritten.
In step S35, it is checked whether or not an out-of-target flag that is a region not subjected to feedback control is set in the rewrite map of the (x, y) coordinates. If there is an out-of-target flag, the data at this coordinate position is not rewritten.
In step S36, the offset value is subtracted from the base map value of the (x, y) coordinate. It is checked whether the subtracted value is greater than or equal to the second map value of (x, y) coordinates (step S37).
[0076]
If the offset subtraction value is greater than or equal to the second map value (richer than the second map value), the offset subtraction value is written into the (x, y) coordinates of the rewrite map (step S38).
[0077]
On the other hand, if the offset subtraction value is less than the second map value (lean side from the second map value), the rewritten map value at the (x, y) coordinate is rewritten to the second map value. (Step S39).
When the number of map counters reaches the total number of maps, the rewriting work is finished (step S40).
[0078]
FIG. 8 is a flowchart of misfire determination.
First, the current map position is calculated from the engine speed and throttle opening data (step S41).
[0079]
Next, in step S42, cylinder discrimination processing is performed. This cylinder discrimination process is performed to discriminate the misfire state for each cylinder. As will be described later, this cylinder discrimination is performed based on a pulsar signal from the camshaft sensor and a pulse signal corresponding to the crank angle from the crank angle sensor.
[0080]
In step S43, the waveform data from the exhaust pressure sensor is taken and the area of the waveform between the predetermined crank angles t1 and t2 is calculated.
In step S44, it is checked whether the waveform area is equal to or smaller than a predetermined value. This predetermined value is for checking the abnormality of the sensor. For example, it is set to a value that is small enough to exceed the amount of area reduction due to misfire.
[0081]
If the waveform area is equal to or smaller than the predetermined value, a timer or a cycle number counter is set in step S45.
In step S46, it is checked whether waveform data equal to or smaller than a predetermined value of the same small area is input during a predetermined time by the timer or a predetermined number of times by the counter. After the predetermined time has passed or the predetermined number of times has been detected, if the exhaust pressure waveform area is not more than the predetermined value, it is determined that the exhaust pressure sensor is abnormal, and a warning display of the exhaust pressure sensor abnormality is displayed (step S47).
[0082]
Subsequently, an emergency operation flag is set in step S48, and the engine is driven with the fuel control valve fixed to the original base map operation program without FB control (step S49).
[0083]
If the area value is not less than the predetermined value in step S44 and there is no abnormality in the sensor, the area moving average value of the waveform from the exhaust pressure sensor at the crank angles t1 to t2 is calculated for each cylinder (step S50).
[0084]
In step S51, the ratio R of the waveform area of the exhaust pressure sensor to the cylinder moving average area is calculated.
In step S52, it is checked whether the ratio R to the average value of each waveform area data is equal to or less than the reference value. This reference value varies depending on the operation region, and misfire is determined for each cylinder based on this reference value. If no misfire has occurred, in step S53, the current waveform data is added and the waveform moving average value of the cylinder-specific exhaust pressure sensor is rewritten.
[0085]
If the waveform area ratio R is equal to or less than the reference value, it is determined in step S54 that misfire has occurred. This misfire determination is performed for each cylinder.
[0086]
Step S55 checks the number of cylinders that misfired. For example, if two or more of the four cylinders misfire, it is determined that the engine is abnormal and the engine is forcibly stopped (step S59). Thereafter, an engine abnormality is displayed (step S60).
[0087]
If the number of misfire cylinders is one, it is checked in step S56 whether the FB control operation is in progress. If the FB control is being performed, the process returns to the routine of the misfire detection step S17 after the aforementioned misfire determination program (step S16) of FIG.
[0088]
If the number of misfire cylinders is one and the FB operation is not in progress, an emergency flag is set in step S57. Subsequently, in step S58, misfire recovery control operation is performed. This is performed, for example, by enriching the opening map of the fuel control valve or changing the ignition timing of the misfire cylinder.
[0089]
FIG. 9 is an explanatory diagram of an engine operation region according to the throttle opening and the engine speed.
In order to obtain an optimum operating state in the entire engine operating region, it is desirable to change the fuel control method according to the operating region. For example, in the region I on the low load side where the throttle opening is small, leaning is suppressed to ensure stable combustion. In the middle region II, priority is given to measures against exhaust gas or combustion efficiency, and fuel control valve feedback control for misfire determination is performed. In the high load region III, fuel control valve feedback control is not performed to ensure output.
[0090]
In the present invention, the second map is provided together with the base map of the fuel control valve opening, and the base map is rewritten while making the fuel lean by learning.
[0091]
Table 1 shows an example of a second map setting method in consideration of the operation characteristics required according to such an operation region.
[0092]
[Table 1]

[0093]
In this second map, priority is given to drivability in a region where the throttle opening is low (A region), and exhaust gas (NOx) reduction is prioritized (B region) or operation efficiency is prioritized (D region) at an intermediate opening. At high opening, priority is given to securing output (C region).
[0094]
FIGS. 10A and 10B are graphs showing data examples of the cylinder discrimination waveform and the misfire discrimination waveform.
As shown in FIG. 10A, a pulsar signal a from a pulsar coil that detects the rotation of the camshaft is input every two rotations (720 degrees) of the crankshaft. A crank angle pulse signal b from the crank angle sensor is input in synchronization with the pulsar signal a. This crank angle signal is output every time when each tooth of a ring gear having 120 teeth is detected, for example, becomes 240 pulse signals in two rotations where a pulsar signal is obtained, and every three crank angles. One pulse is input. The detection position of this pulsar signal is set to BTDC 90 degrees for the # 1 cylinder, for example. Thus, for example, in a four-cylinder engine that is ignited in the order of # 1 → # 3 → # 4 → # 2, for example, the crank from the detection position of the pulsar signal for each of the four cylinders whose exhaust pressure is detected every 90 degrees. The cylinder number is determined by the angle.
[0095]
Since the combustion conditions of each cylinder are slightly different, the exhaust pressure waveform of each cylinder is also different. In the present invention, by determining the cylinder and determining misfire for each cylinder in this way, it is possible to perform optimum feedback control corresponding to the exhaust pressure waveform of each cylinder.
[0096]
FIG. 10B shows exhaust pressure detection data for four cylinders. A solid line graph c is a normal exhaust pressure waveform, and a dotted line graph d is a misfire exhaust pressure waveform. From such waveform detection data, the area of the waveform is calculated for each cylinder, and misfire is determined based on this waveform area. In this case, the integration start crank angle t1 and the integration end crank angle t2 after compression top dead center are set in the waveform data of each cylinder.
[0097]
A predetermined cylinder is ignited at a predetermined crank angle, and exhaust gas reaches an exhaust pressure sensor part in the middle of the exhaust pipe through an explosion and exhaust stroke. In consideration of the crank angle until the exhaust gas reaches (depending on the engine speed), t1 and t2 are set for each cylinder corresponding to the ignition timing for each cylinder so that the exhaust pressure data can be taken in across the peak of the exhaust pressure waveform. It is decided.
[0098]
The waveform area between the crank angles t1 and t2 is calculated for each cylinder, and this is compared with the moving average value of the immediately preceding predetermined cycle. The ratio R with respect to the average value of the waveform area is compared with the reference value stored in the map to determine misfire. This reference value differs for each map coordinate corresponding to the driving region.
[0099]
FIG. 11 is a three-dimensional view showing a map of reference values for misfire determination.
As shown in the figure, the misfire determination criterion (%) is varied depending on the map coordinate position corresponding to the throttle opening and the engine speed. In this example, the misfire determination criterion is low on the high rotation and high throttle opening side, and the reference is high on the low rotation and low throttle opening side. Therefore, on the high rotation and high load side, the exhaust pressure waveform area described above is greatly reduced compared to the average value, and for example, in a high load region of 2000 rpm or more, the ratio R is not determined to be less than 20%. Will continue. On the other hand, on the low rotation and low load side, when the ratio R of the exhaust pressure waveform area becomes 30 to 40%, it is determined that misfire has occurred and leaning is stopped.
[0100]
In this way, by changing the misfire determination criterion according to the operation region, an optimal operation state can be obtained over the entire operation region in combination with the formation of the second map according to the desired priority characteristic for each operation region. It is done.
[0101]
Instead of obtaining a ratio R to the average value of the exhaust pressure waveform area and comparing it with a reference value, a difference between the exhaust pressure waveform area and the average value is obtained and this difference is determined in advance as a predetermined reference value. Misfire may be determined by comparing with (this reference value also varies depending on the operation region).
[0102]
In the present embodiment, the fuel gas that has passed through the fuel control valve 29 is mixed with air in the mixer 24, and after the flow rate of the mixer is adjusted in the mixer 24, the fuel gas is sucked into the engine 4. For this reason, the air-fuel ratio is controlled by adjusting the amount of fuel gas by the fuel control valve 29. Therefore, in the case of a multi-cylinder engine, the misfire recovery of the misfire cylinder as a result of the misfire determination for each cylinder can be effectively achieved by combining the ignition timing control for each individual cylinder in addition to the air-fuel ratio control.
[0103]
In addition, a mixer is arranged in each distribution pipe to each cylinder of the intake manifold, and fuel gas is guided to each of the mixers via a separate fuel control valve, and intake air is introduced upstream of the internal distribution pipe of the intake manifold. When a throttle valve that controls the amount is installed, the misfire recovery of the misfire cylinder as a result of the misfire determination for each cylinder can be achieved by finely adjusting the opening degree of the fuel control valve corresponding to the misfire cylinder. It is. In this case, ignition timing control for each individual cylinder may be combined.
[0104]
【The invention's effect】
As described above, in the present invention, since the rotation speed of the gas engine or the compressor is controlled according to the pressure of the gas tank on the compressor discharge side, the output control of the gas engine is performed with the optimum efficiency according to the pressure. be able to.
[0105]
In addition, as a base map for lean combustion control, for example, fuel supply amount data that does not cause misfire, which is known in advance, is set, and a second map that is set leaner than the base map is provided. The fuel is gradually leaned until misfire, and if the fuel supply amount at the time of misfire or the second map is reached before the misfire, the base map is rewritten with the fuel supply amount of the second map. As a result, a map based on the combination of the misfire limit and the second map is formed by learning, and the fuel control map can be formed by taking into account the second map that provides the preset desired characteristics with respect to the misfire limit map. Such misfire learning control can quickly follow rapid changes in engine load and engine speed, achieve optimal lean combustion according to the operating state, and can effectively reduce NOx and improve fuel efficiency. .
[0106]
In this case, the second map is set so as to give priority to the different operating characteristics for each map formation region corresponding to the engine speed and the throttle opening, and to obtain the leanest fuel supply amount that can obtain the operating characteristics. For example, in this second map, fuel supply amount data that matches the operating characteristics required in each operating region corresponding to the engine speed and throttle opening is set, so that operation within the misfire limit range is possible. Fuel control is performed with optimum operation characteristics according to the region.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a gas filling apparatus to which the present invention is applied.
FIG. 2 is a graph showing the relationship between the filling pressure of the gas filling device of FIG. 1 and the engine speed.
FIG. 3 is a configuration diagram of a control system of the gas filling device in FIG. 1;
FIG. 4 is a flowchart of an operation control program for a fuel control valve according to an embodiment of the present invention.
FIG. 5 is a flowchart of a main program of the fuel control method of the present invention.
6 is a flowchart of a learning program in the flowchart of FIG.
7 is a flowchart of a rewrite program in the flowchart of FIG.
FIG. 8 is a flowchart of a misfire determination program according to the present invention.
FIG. 9 is a graph of an engine operating region.
FIG. 10 is a graph of waveform data for cylinder discrimination and misfire determination.
FIG. 11 is a three-dimensional view showing a map of misfire determination criteria.
[Explanation of symbols]
1: gas filling device, 2: gas inlet, 3: casing, 4: engine,
5: Compressor, 6: Gas cooler, 8: Exhaust port, 10: Main ventilation fan,
13: Crankshaft, 21: Air cleaner, 23: Throttle valve,
24: mixer, 25: throttle valve opening / closing drive motor,
26: piping for fuel gas supply, 28: pressure reducing adjustment valve,
29: Fuel gas flow rate control valve (fuel control valve), 34: Radiator,
35: Cooling water pump, 42: Compressor outlet pipe, 43: Gas supply source valve,
44: Total gas flow meter, 45: Check valve, 46: Dehumidifier
48: first pressure sensor, 51: filling coupler socket,
52: Sensor for checking filling hose connection, 54: Oil filter,
55: Second pressure sensor, 56: Blowdown valve,
57: blowdown tank, 58: relief valve, 59: discharge port,
61: heating device, 63: air heating pipe, 64: suction pipe,
65: Air cleaner, 71: Control device, 72: Operation changeover switch,
73: 1st temperature sensor, 74: 2nd temperature sensor,
75: Third temperature sensor, 76: Fourth temperature sensor,
77: Fifth temperature sensor, 78: Gas leak detector,
80: throttle valve opening sensor, 82: memory, 110: one-way clutch,
111: Fan drive shaft, 112: Transmission, 113: Rotating machine,
114: pulley

Claims (4)

In a lean combustion control method of a gas engine in a gas filling machine comprising a compressor that compresses fuel gas and fills a gas tank, and a gas engine that drives the compressor,
Detecting the gas pressure sent from the compressor to the gas tank, and controlling the rotational speed of the gas engine or the compressor based on this,
Using a map based on the preset engine speed and throttle opening,
The map has a base map and a second map in which the fuel supply amount is set on the lean side from the base map,
During fuel supply controlled by the base map, the fuel is gradually leaned while judging misfire,
Gas filling, wherein leaning is stopped when the misfire or the second map is reached, the fuel supply amount is learned, the base map is rewritten, and the fuel supply amount is controlled according to the rewritten base map A lean combustion control method for a gas engine in an apparatus. The second map is set to give the leanest fuel supply amount that gives priority to the different driving characteristics for each map formation region corresponding to the engine speed and the throttle opening, and obtains the driving characteristics. The lean combustion control method for a gas engine in the gas filling device according to claim 1. 3. The gas filling device according to claim 1, wherein when the base map is rewritten, the same offset amount is rewritten in a richer range than the second map in other regions as well as the controlled region. A lean combustion control method for a gas engine. 4. The gas in the gas filling device according to claim 1, wherein when the misfire is determined, lean is performed step by step, and when misfire is detected, the gas is returned to the rich side by a predetermined step within a range on the lean side from the base map. Engine lean combustion control method.

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