WO2006112414A1

WO2006112414A1 - Diesel engine fuel injection amount control device

Info

Publication number: WO2006112414A1
Application number: PCT/JP2006/307978
Authority: WO
Inventors: Masato Takeuchi; Hitoshi Hosaki
Original assignee: Kabushiki Kaisha Toyota Jidoshokki; Toyota Jidosha Kabushiki Kaisha
Priority date: 2005-04-15
Filing date: 2006-04-14
Publication date: 2006-10-26
Also published as: EP1870587A4; EP1870587B1; EP1870587A1; JP2006299833A

Abstract

A control computer (C) contains a map shown in Fig. 1(b). Curve (h1) expresses a part of a map set corresponding to a transient state. Curve (h2) expresses a part of a map set corresponding to a non-transient state. The map as a set of a plenty of curves including the curve (h1) is first injection amount upper limit information predetermined in accordance with an oxygen amount-associated value and the transient state. The map as a set of a plenty of curves including the curve (h2) is second injection amount upper limit information predetermined in accordance with an oxygen amount-associated value and the non-transient state. By using these maps, the control computer (C) specifies the injection amount upper limit value appropriate for each of the transient state and the non-transient state.

Description

Specification

Fuel injection amount control device for diesel engine

Technical field

[0001] The present invention relates to a fuel injection amount control device applied to a diesel engine.

Background art

[0002] Patent Document 1 discloses a fuel injection in which a specific control pattern is selected from a plurality of maximum injection amount control patterns according to the shift position of the transmission, and the maximum injection amount is controlled according to the selected control pattern. A quantity control device is disclosed.

[0003] Patent Document 2 discloses a fuel injection amount control device including a first calculation means for calculating the intake air amount during steady operation and a second calculation means for calculating the intake air amount during acceleration operation. ing. The first calculating means calculates the intake air amount during steady operation based on the intake air amount detected by an air flow meter or the like. The second calculating means calculates the intake air amount during acceleration operation based on the throttle opening and the engine speed. Then, when the engine operating state is switched from steady operation to acceleration operation, the larger one of the intake air amount obtained by the first calculating means and the intake air amount obtained by the second calculating means is selected. The fuel injection amount is determined based on the selected intake air amount and the engine speed.

Patent Document 1: Japanese Utility Model Publication No. 1 118143

Patent Document 2: Japanese Patent Laid-Open No. 4-365943

Disclosure of the invention

[0004] Increasing the fuel injection amount is advantageous for increasing torque, but tends to generate black smoke.

For this reason, the upper limit value of the fuel injection amount is an important factor in considering avoidance of black smoke generation and higher torque.

[0005] The upper limit value of the fuel injection amount is set based on the amount of oxygen taken into the combustion chamber. The amount of oxygen in the combustion chamber is measured, for example, by detecting the intake pressure, but there is a response delay in the intake during transition from steady operation to acceleration operation (transient state). Intake pressure tends to be low. At high places, the air pressure is lower than that on flat ground, so the intake pressure during steady operation tends to be low. In this way, intake air varies depending on the vehicle running conditions and driving environment. Since the pressure changes, the upper limit of the fuel injection amount may be different even at the same engine speed and engine load.

[0006] Furthermore, fuel may be injected at different injection timings during steady operation and acceleration operation. In this case, the upper limit value of the fuel injection amount is maintained even with the same intake pressure (oxygen amount). Is different.

[0007] However, Patent Document 1 discloses the idea of! / ヽぅ when the injection amount upper limit value is determined that is appropriate for the same intake pressure, during steady operation, that is, a non-transient state and a transient state, respectively. !

[0008] Further, in Patent Document 2, fuel is injected based on the larger intake amount of the intake air amounts calculated by the pair of calculating means in the transient state, but the same intake pressure is maintained. When the injection amount upper limit value suitable for the non-transient state and the transient state is determined, the idea is not disclosed.

An object of the present invention is to provide a fuel injection amount control device for a diesel engine that determines an injection amount upper limit value suitable for each of a non-transient state and a transient state.

In order to solve the above-described problem, according to the first aspect of the present invention, in a diesel engine equipped with a fuel injection device, it is detected whether the operating state of the engine is a transient state or a non-transient state. The state detection means, the value related to the amount of oxygen sucked into the cylinder, the first injection amount upper limit information determined in advance corresponding to the transient state, and the value related to the amount of oxygen sucked into the cylinder And second injection amount upper limit information determined in advance corresponding to the non-transient state, and when the engine operating state is in a transient state, fuel injection is performed using the first injection amount upper limit information. A specific means for specifying the fuel injection amount upper limit value using the second injection amount upper limit value information when the engine operating state is in a non-transient state, and specifying means. The fuel injection amount is less than the upper limit of the injection amount And control means.

By configuring as described above, the specifying means specifies the fuel injection amount upper limit value using the first injection amount upper limit value information when the engine operating state is in a transient state, and the engine The fuel injection amount upper limit value is specified by using the second injection amount upper limit value information when the operation state is non-transient. The first injection amount upper limit value information is information on the injection amount upper limit value determined in advance corresponding to the oxygen amount related value and the transient state, and the injection amount upper limit value is the fuel injection amount suitable for the transient state. This is the limit value. The second injection amount upper limit information is oxygen amount It is information on the injection amount upper limit value determined in advance corresponding to the related value and the non-transient state, and the injection amount upper limit value is a limit value of the fuel injection amount suitable for the non-transient state. In this case, it is possible to specify an injection amount upper limit value that is suitable for each of the non-transient state and the transient state, and it is possible to inject fuel corresponding to each injection amount upper limit value.

[0012] The fuel injection amount control apparatus includes a detection unit that detects a value related to the amount of oxygen sucked into the cylinder, and the first injection amount upper limit information includes a first value related to the oxygen amount related value. The calculation formula for the first injection amount upper limit value having the correction coefficient, and the second injection amount upper limit value information is the calculation formula for the second injection amount upper limit value having the second correction coefficient for the oxygen amount related value. When the engine operating state is in a transient state, the specifying means determines the first oxygen amount related value in the first injection amount upper limit information based on the oxygen amount related value detected by the detecting means. When the engine operating state is a non-transient state, the specifying means determines the oxygen amount related value in the second injection amount upper limit information based on the oxygen amount related value detected by the detecting means. It is desirable to specify the second correction factor. According to this configuration, by specifying the first and second correction coefficients for the oxygen amount related value, it is possible to easily determine the injection amount upper limit value that is suitable for each of the non-transient state and the transient state.

[0013] In the fuel injection amount control device described above, it is desirable that the detection means is intake pressure detection means for detecting intake pressure. According to this configuration, the oxygen pressure related value can be detected with high accuracy by the intake pressure detecting means.

[0014] In the fuel injection amount control device described above, it is desirable that the diesel engine performs the nozzle injection prior to the main injection. In the fuel injection amount control apparatus described above, it is preferable that the control means controls the fuel injection amount by changing the injection period of pilot injection. In the above fuel injection amount control apparatus, it is desirable that the control means controls the fuel injection amount by changing the start timing of the nozzle injection. According to these configurations, it is possible to improve fuel efficiency and reduce noise generated during combustion. Brief Description of Drawings

FIG. 1 (a) is a schematic diagram showing the overall configuration of a diesel engine and a fuel injection amount control device. (B) is a map showing the relationship between the intake pressure and the intake pressure correction coefficient.

FIG. 2 is a flowchart for explaining control for specifying an intake pressure correction coefficient. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment in which the fuel injection device of the present invention is applied to a vehicle diesel engine will be described with reference to FIG. 1 and FIG.

As shown in FIG. 1 (a), the diesel engine 10 includes a plurality of cylinders 11 and a cylinder head 12. A plurality of fuel injection nozzles 13 are attached to the cylinder head 12 so as to correspond to the respective cylinders 11. Each fuel injection nozzle 13 injects fuel (light oil) into each cylinder 11. In the present embodiment, fuel is supplied from each fuel injection nozzle 13 into each cylinder 11 by pilot injection and main injection performed after pilot injection. Specifically, the main injection is started after the piston in the cylinder 11 reaches the compression top dead center, and the pilot injection is started before the piston in the cylinder 11 reaches the compression top dead center.

An intake bear-hold 14 is connected to the cylinder head 12. The intake manifold 14 is connected to an intake passage 15, and the intake passage 15 is connected to an air cleaner 17. A throttle valve 18 is provided in the intake passage 15. The opening of the throttle valve 18 is adjusted according to the engine speed and the engine load. By controlling the opening degree of the throttle valve 18, the flow rate (intake amount) of air introduced into the intake bear hold 14 via the air cleaner 17 and the intake passage 15 is adjusted. The vehicle is also provided with an accelerator opening detector 19 that detects the depression angle (accelerator opening) of the accelerator pedal and a crank angle detector 20 that detects the rotation angle (crank angle) of the crankshaft of the engine. . Both the accelerator opening detector 19 and the crank angle detector 20 are connected to a control computer C that controls various controls of the vehicle, and the accelerator opening detector 19 receives information on the accelerator opening. Information on the crank angle is taken into the control computer C from the angle detector 20. The control computer C calculates the engine speed based on the time change of the crank angle, and calculates the engine load F based on the accelerator opening.

The diesel engine 10 is equipped with a variable nozzle turbocharger (hereinafter referred to as a supercharger) 16 that operates using exhaust gas discharged from each cylinder 11. In the intake passage 15, a compressor section 161 of the supercharger 16 is provided. In intake passage 15 The throttle valve 18 is provided between the compressor section 161 of the supercharger 16 and the intake bear-hold 14. The air sent out from the compressor unit 161 passes through the intake passage 15 and the intake bear-hold 14 and is supplied to each cylinder 11.

[0020] The intake bear hold 14 has an intake air temperature detector 23 that detects the temperature of the air supplied to each cylinder 11 (intake air temperature), and a pressure that detects the pressure in the intake bear hold 14 (intake air pressure). A detector 24 is provided. The intake air temperature detector 23 and the pressure detector 24 are both connected to the control computer C. Information on the intake air temperature detected by the intake air temperature detector 23 and information on the intake air pressure detected by the pressure detector 24 are taken into the control computer C, respectively.

In the cylinder head 12, an exhaust motor hold 21 is connected to the side opposite to the intake bear hold 14. The exhaust motor hold 21 is connected to the exhaust passage 22. A turbine section 162 of the supercharger 16 is provided in the exhaust passage 22. Exhaust gas generated in each cylinder 11 passes through an exhaust motor hold 21 and is discharged into an exhaust passage 22.

[0022] The control computer C calculates the injection amount upper limit value Q1 based on the following calculation formula [1] of the first injection amount upper limit value, or calculates the second injection amount upper limit value [ Based on 2), calculate the injection quantity upper limit Q2.

[0023] Ql = Hl XTX Qo---[1]

Q2 = H2 XTX Qo-"[2]

Qo is the upper limit of injection amount at standard atmospheric pressure (= 1 atm), HI and H2 are the first and second intake pressure correction factors, respectively, and T is the intake air temperature. Here, the first intake pressure correction coefficient HI is a first correction coefficient for the oxygen amount related value, and the second intake pressure correction coefficient H2 is a second correction coefficient for the oxygen amount related value.

The control computer C stores the map shown in FIG. 1 (b). The curve hi in Fig. 1 (b) represents a part of the map of the first intake pressure correction coefficient HI in the transient state (hereinafter referred to as map Ml), and the curve h2 represents the second intake pressure correction coefficient in the non-transient state. This represents a part of the H2 map (hereinafter referred to as map M2). Curves hi and h2 are set according to the intake pressure and the engine speed. In other words, the map Ml shows the intake pressure and the first This represents the relationship with the atmospheric pressure correction coefficient HI, and also represents the collective power of the curve set for each engine speed. Similarly, the map M2 represents the relationship between the intake pressure in the non-transient state and the second intake pressure correction coefficient H2, and consists of a set of curves set for each engine speed. In the present embodiment, the map Ml including the curve hi and the map M2 including the curve h2 are information of the first and second intake pressure correction coefficients HI and H2, respectively, and are determined in advance according to the intake pressure. .

As shown in FIG. 1 (b), the first and second intake pressure correction coefficients HI and H2 are set to increase as the intake pressure increases. This is because the amount of oxygen increases as the intake pressure increases. Further, the first and second intake pressure correction coefficients HI and H2 are set to increase as the engine speed increases.

Next, control for specifying the intake pressure correction coefficient by the control computer C will be described with reference to the flowchart of FIG. This control is repeatedly executed by the control computer C at a predetermined cycle.

[0027] First, the control computer C captures various detection information such as the engine speed Nx, the accelerator opening Kx, the intake pressure Ρχ, and the engine load F (step S1). Based on the engine speed Nx and the engine load F, the control computer C determines the target intake pressure Po during steady operation (step S2). Then, the control computer C controls the vane opening of the turbine section 162 of the supercharger 16 so that the current intake pressure Px matches the target intake pressure Po.

[0028] The control computer C compares the current accelerator opening Kx with a preset accelerator opening Ko (step S3). If the current accelerator opening Kx is greater than or equal to the accelerator opening Ko (YES in step S3), the control computer C predetermines the difference between the detected intake pressure Px and the target intake pressure Po, I Px—Po I, in advance. The set reference value α is compared (step S4).

[0029] When difference I Px-Po I is a reference value (when X is greater than or equal to X (YES in step S4)), control computer C determines that the engine operating state is a transient state, and based on the determination result, The engine speed Nx, the intake pressure Px, and the map Ml are used to identify the first intake pressure correction coefficient HI (step S5), and the control computer C calculates the determined first intake pressure correction coefficient HI and the formula [1]. Are used to calculate the injection amount upper limit value Q 1 (step S6).

[0030] The current accelerator opening Kx does not reach the accelerator opening Ko! /, If (NO in step S3), Or if the difference I Px—Po I does not reach the reference value a (NO in step S4), the control converter C determines that the engine operating state is a non-transient state, and based on the determination result. Then, the second intake pressure correction coefficient H2 is specified using the engine speed Nx, the intake pressure Px and the map M2 (step S7). The control computer C calculates the injection amount upper limit value Q2 using the specified second intake pressure correction coefficient H2 and the calculation formula [2] (step S8).

[0031] After the process of step S8, the control computer C specifies the basic fuel injection mode to be performed during the steady operation based on the engine speed Nx, the accelerator opening KX, and the like (step S9). The basic fuel injection mode includes a main injection start timing and injection period, a pilot injection start timing and injection period, and a fuel injection amount determined by the injection period. At this time, when the fuel injection amount becomes equal to or greater than the injection amount upper limit value Q2, the basic fuel injection mode is changed so that the fuel injection amount value becomes Q2. The fuel injection amount in the basic fuel injection mode specified in this way is set to the injection amount upper limit value Q2 or less obtained in step S8.

[0032] On the other hand, after the processing of step S6, the control computer C specifies the basic fuel injection mode to be performed during steady operation based on the engine speed Nx (step S10). Then, after specifying the basic fuel injection mode, the control computer C corrects the start timing and injection period of main injection and the start timing and injection period of no-lot injection (step Sl 1). The transient fuel injection amount corrected in this way is set to the injection amount upper limit value Q1 or less obtained in step S6 by the same operation as in step S9. In this step S11, the basic fuel injection mode obtained in step S10 is corrected so that the pilot injection start timing is earlier than that in the steady operation. By this correction, the injection period of pilot injection (pilot injection amount) is extended compared to that during steady operation.

[0033] The control computer C performs pilot injection at the start timing and the injection period thus determined. After the pilot injection is completed, the control computer C performs the main injection amount at the determined start timing and injection period. By performing such advance angle control, the generation of black smoke is avoided and the maximum fuel injection amount is increased while achieving high torque. Conventionally, the maximum fuel injection amount is specified based on the intake pressure related to the engine operating state. Compared with this method, it is possible to increase the fuel injection amount by extending the injection period during the transient operation, thereby improving the acceleration response.

[0034] The accelerator opening detector 19 is an engine load detecting means. The crank angle detector 20 and the control computer C constitute engine speed detecting means for detecting the engine speed. The pressure detector 24 is intake pressure detection means as detection means. The control computer C, together with the pressure detector 24 and the engine speed detection means, constitutes state detection means for detecting whether the engine operating state is a transient state or a non-transient state. Further, the control computer C specifies the injection amount upper limit value using the first injection amount upper limit value information (calculation formula [1]) when the engine operating state is in a transient state, and the engine operating state is not determined. It is also a specifying means for specifying the injection amount upper limit value using the second injection amount upper limit information (calculation formula [2]) in the transient state. Furthermore, the control computer C is also a control means for performing fuel injection within a range that is equal to or less than the specified first and second injection amount upper limit values.

According to the present embodiment, the following effects can be obtained.

(1) When the engine operating state is in a transient state, the control computer C specifies the injection amount upper limit value Q1 using the calculation formula [1], and the engine operating state is in a non-transient state. In this case, the injection amount upper limit value Q2 is specified using the calculation formula [2]. The calculation formula [1] is information on the injection amount upper limit value Q1 determined in advance corresponding to the oxygen amount related value and the transient state (first injection amount upper limit value information), and the injection amount upper limit value Q1 is This is the upper limit of the fuel injection amount suitable for the transient state. The calculation formula [2] is information (second injection amount upper limit value information) of the injection amount upper limit value Q2 determined in advance corresponding to the oxygen amount related value and the transient state, and the injection amount upper limit value Q 2 Is the upper limit value of the fuel injection amount adapted to the non-transient state. In this case, it is possible to specify the injection amount upper limit value that is suitable for each of the non-transient state and the transient state, and it is possible to cause the fuel to be injected in accordance with each injection amount upper limit value. As a result, generation of black smoke can be avoided and torque can be improved.

[0037] (2) When the engine operating state is a transient state, the control computer C specifies the first intake pressure correction coefficient HI of the calculation formula [1] based on the intake pressure from the pressure detector 24. . On the other hand, when the engine operating state is a non-transient state, the control computer C specifies the second intake pressure correction coefficient H2 in the calculation formula [2] based on the intake pressure from the pressure detector 24. . Thus, by specifying the respective intake pressure correction coefficients HI and H2, it is possible to easily determine the upper limit value of the injection amount suitable for the non-transient state and the transient state.

(3) The pressure detector 24 detects a value (intake pressure) related to the amount of oxygen sucked into the cylinder 11. The pressure detector 24 can detect the amount of oxygen with high accuracy.

(4) In the present embodiment, fuel is supplied from each fuel injection nozzle 13 into each cylinder 11 by pilot injection and main injection performed after pilot injection. In this case, the small amount of fuel injected by the pilot injection is not burned immediately but can be burned gently together with the fuel injected at the beginning of the main injection. As a result, the combustion pressure and the combustion temperature can be kept low, so that fuel efficiency can be improved and noise generated during combustion can be reduced.

[0040] (5) In the transient state, the control computer C corrects the pilot injection start timing earlier than during steady operation. By this correction, the injection period of pilot injection is extended from that during steady operation. As a result, fuel efficiency can be improved, noise generated during combustion can be reduced, and torque can be improved.

[0041] The present embodiment may be modified as follows! /.

In the present embodiment, an air flow meter that detects the flow rate of the air flowing through the intake passage 15 may be used as the detection means.

In this embodiment, pilot injection may not be used as a method of supplying fuel from each fuel injection nozzle 13 into each cylinder 11.

[0044] 'In the present embodiment, the turbocharger 16 may not be mounted on the diesel engine 10.

[0045] 'In this embodiment, when determining the operating state of the engine, the control computer C determines that the current accelerator opening Kx is greater than or equal to the preset accelerator opening Ko, and the unit time of the accelerator opening Κχ. If the amount of change per hit is greater than or equal to a predetermined value, it may be determined that the transition is in half.

[0046] In this embodiment, the control computer C calculates the injection amount upper limit Q1 with the first intake pressure correction coefficient HI of the calculation formula [1] being 1, and the second intake pressure correction of the calculation formula [2]. The injection amount upper limit value Q2 may be calculated with a coefficient Η2 of 1.

Claims

The scope of the claims

[1] In a diesel engine equipped with a fuel injection device, state detecting means for detecting whether the engine operating state is a transient state or a non-transient state;

First injection amount upper limit information determined in advance corresponding to a value related to the amount of oxygen sucked into the cylinder and a transient state, and a value related to the amount of oxygen sucked into the cylinder and a non-transient state The second injection amount upper limit value information determined in advance corresponding to is stored, and when the engine operating state is in a transient state, the fuel injection amount using the first injection amount upper limit value information is stored. A specifying unit that specifies an upper limit value, and specifies the fuel injection amount upper limit value using the second injection amount upper limit value information when the engine operating state is a non-transient state; Control means for injecting fuel with an injection amount less than or equal to the upper limit of the injection amount;

A fuel injection amount control device for a diesel engine comprising:

[2] comprising detection means for detecting a value related to the amount of oxygen sucked into the cylinder;

The first injection amount upper limit value information is a calculation formula for a first injection amount upper limit value having a first correction coefficient for an oxygen amount related value, and the second injection amount upper limit information is related to an oxygen amount related value. When the engine operating state is in a transient state, the specifying means is an oxygen amount related value detected by the detecting means. The first correction coefficient of the oxygen amount related value in the first injection amount upper limit value information is specified based on the first injection amount upper limit value information, and when the engine operating state is a non-transient state, the specifying unit is detected by the detecting unit 2. The fuel injection amount control device for a diesel engine according to claim 1, wherein a second correction coefficient of the oxygen amount related value in the second injection amount upper limit value information is specified based on the determined oxygen amount related value.

3. The fuel injection amount control device for a diesel engine according to claim 2, wherein the detection means is intake pressure detection means for detecting intake pressure.

4. The fuel injection amount control device for a diesel engine according to any one of claims 1 to 3, wherein pilot injection is performed prior to main injection in the diesel engine.

[5] The control means controls the fuel injection amount by changing an injection period of the pilot injection. The fuel injection amount control device for a diesel engine according to claim 4.

6. The fuel injection amount control device for a diesel engine according to claim 5, wherein the control means controls a fuel injection amount by changing a start timing of the pilot injection.