JP2016156362A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide am engine control device which enhances the detection accuracy of operation vibration when controlling an operation state of an engine on the basis of a detection value of the operation vibration which is generated at an engine main body.SOLUTION: An ECU 8 creates map data on an engine rotational speed and a drift value of a detection value from the detection value of operation vibration by a vibration acceleration sensor 3 and a measurement value of an engine rotation sensor 9 at the inertia traveling of a vehicle. The ECU comprises: an injection control part 11 for controlling fuel injection on the basis of an injector characteristic map; a minimum pulse width learning part 12 which outputs an injection command signal in which a pulse width is increased stepwise from a minute width to an injector 4, and when the detection value of the operation vibration which is generated when the injector 4 performs fuel injection exceeds a determination threshold indicating a pre-stored injection start, learns a pulse width outputted at this time as a minimum pulse width; and an injector characteristic correction part 13 which corrects the injector characteristic map at the learnt minimum pulse width. Consequently, the detection value of the operation vibration is corrected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine control device, and more specifically, engine control that improves control results by increasing the detection accuracy of operating vibrations when controlling the operating state of the engine based on detected values of operating vibrations generated in the engine body. Relates to the device.

  2. Description of the Related Art Conventionally, there is known a common rail type fuel injection device that directly injects high pressure fuel pressured on a common rail into each cylinder of an engine from an injector. In general, in a common rail type fuel injection device, pilot injection for injecting a minute amount of fuel is performed before main injection in order to reduce combustion noise and improve exhaust gas performance.

  In order to reduce the combustion noise, etc., it is required to perform pilot injection with a smaller injection amount. However, since the pilot injection has a small injection amount, it is likely to be affected by variations due to individual differences among injectors and aging, and it is necessary to provide a certain amount of allowance for the injection amount.

  As a technique for improving the accuracy of such pilot injection, a learning control device that detects the combustion state of each cylinder by a knock sensor and corrects the pilot injection amount is known (see, for example, Patent Document 1).

  However, in the technique of detecting the combustion state in the micro injection region with the knock sensor as in the above-described technique, the vibration is very small and sufficient S / N cannot be secured, so the pilot injection amount is reduced to a smaller injection amount. There is a possibility that it cannot be corrected.

  The inventor therefore injects fuel into the cylinder of the engine in accordance with the pulse width of the instruction signal, a knock sensor that detects operating vibrations that occur when the injector performs fuel injection, and a fuel injection amount stored in advance. And injection control means for controlling the fuel injection of the injector based on the injector characteristics indicating the relationship between the injection instruction signal and the pulse width of the injection instruction signal, and the injection instruction signal for increasing the pulse width stepwise from the minute width to the injector When the operating vibration detected by the knock sensor exceeds a pre-stored determination threshold value indicating the start of injection by the operation of the injector, the learning means for learning the pulse width output at this time as the minimum pulse width necessary for the minute injection of fuel And a correction method for correcting the pulse width corresponding to the minute injection amount of the injector characteristic with the learned minimum pulse width. It devised a fuel injection control device for an engine with and.

  However, in the detection of engine operating vibration by the knock sensor, there is a problem that the detected value varies because the vibration state of the engine body, for example, the cylinder block, changes due to the difference in engine rotation speed.

Japanese Patent Laid-Open No. 11-173200

  An object of the present invention is to provide an engine control device capable of improving the control result by increasing the detection accuracy of operating vibration when controlling the operating state of the engine based on the detected value of operating vibration generated in the engine body. There is to do.

  An engine control apparatus of the present invention that achieves the above object controls vibration detection means for detecting an operating vibration generated in an engine body formed with a plurality of cylinders, and controls engine operation based on a detection value of the vibration detection means. The control means learns the amount by which the detected value drifts due to the difference in engine rotation speed in the engine body during the inertial running of the engine, and then determines the drift amount. After the completion of learning, injection for learning the minimum injection pulse width is performed.

  According to the engine control device of the present invention, the detected value of the operating vibration generated in the engine main body is corrected based on the map data indicating the relationship between the engine rotation speed learned during the inertia traveling of the vehicle and the drift value of the operating vibration. As a result, the control result of the operating state of the engine can be improved by increasing the detection accuracy of the operating vibration.

It is the schematic of the engine control apparatus which consists of embodiment of this invention. It is a graph which shows the example of an injector characteristic map. It is a time chart explaining learning of the minimum pulse width

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an engine control apparatus according to an embodiment of the present invention.

  This engine control device (hereinafter, referred to as “control device”) is configured by a plurality of cylinders from an injector 4 based on a detection value of a vibration acceleration sensor 3 attached to a cylinder block 2 of a diesel engine 1 mounted on a vehicle. The pilot injection amount of fuel into # 1 to # 4 is controlled.

  In addition, although the in-line 4-cylinder engine provided with four cylinders # 1- # 4 is shown as the diesel engine 1, it is not restricted to this, It is a multi-cylinder engine other than 4 cylinders, or a single cylinder engine, Also good.

  The common rail 5 pressure-accumulates high-pressure fuel supplied from a fuel tank (not shown) via a supply pump 6 and distributes the pressure-accumulated high-pressure fuel to the injectors 4. The common rail 5 is provided with a common rail pressure sensor 7 capable of detecting a common rail pressure corresponding to the fuel injection pressure. The detected common rail pressure is supplied to an electrically connected electronic control unit (ECU) 8. Is output.

  The injectors 4 are provided corresponding to the cylinders # 1 to # 4 of the diesel engine 1, respectively, and directly inject high-pressure fuel supplied from the common rail 5 into the combustion chambers of the cylinders # 1 to # 4. The fuel injection amount and injection timing of the injector 4 are controlled by opening and closing the injection hole at the tip of the nozzle by lifting the core valve according to the pulse width (time width) of the injection instruction signal input from the ECU 8 to the electromagnetic solenoid. The

  The vibration acceleration sensor 3 can detect mechanical operating vibration generated when the injector 4 injects fuel, and is attached to each injector 4. As the vibration acceleration sensor 3, a knock sensor used for detecting knocking of a gasoline engine is preferably used. The operating vibration of each injector 4 detected by the vibration acceleration sensor 3 is output to the electrically connected ECU 8.

  The vibration acceleration sensor 3 is attached to the cylinder block 2 of the diesel engine 1. However, the vibration acceleration sensor 3 is not limited to this, and can be attached to other parts such as a cylinder head as long as the vibration can be detected. . Further, it is not necessary to provide each corresponding to each of the cylinders # 1 to # 4. For example, one is provided between the cylinder # 1 and the cylinder # 2, and one is provided between the cylinder # 2 and the cylinder # 3. A total of two vibration acceleration sensors 3 can be attached.

  The ECU 8 performs various controls of the diesel engine 1 and includes a known CPU, ROM, RAM, input port, output port, and the like. In order to perform these various controls, output signals from the vibration acceleration sensor 3, the common rail pressure sensor 7, the engine rotation sensor 9, the accelerator opening sensor 10, and the like are input to the ECU 8.

  Further, the ECU 8 includes an injection control unit 11 that is an injection control unit, a minimum pulse width learning unit 12 that is a learning unit, and an injector characteristic correction unit 13 that is a correction unit as part of functional elements. Here, each of these functional elements 11, 12, 13 is assumed to be included in the ECU 8. However, any one of them may be provided in separate hardware.

The injection control unit 11 controls the fuel injection of each injector 4 based on the operating state of the diesel engine 1. In the memory of the ECU 8, for example, as shown in FIG. 2, the injector characteristics indicating the relationship between the pulse width PW of the injection instruction signal input to the injector 4 and the fuel injection amount Q for each predetermined common rail pressure AC. A map is stored in advance. This injector characteristic map is created separately for each injector 4. Further, the memory of the ECU 8 stores a target injection amount setting map (not shown) indicating the relationship between the operation state of the diesel engine 1 and the fuel target injection amount Q _T.

When performing the injection control, first, the target injection amount Q _T corresponding to the operation state using the engine speed and the accelerator opening as parameters is read from the target injection amount setting map. Then, a pulse width PW corresponding to the target injection amount Q _T is read from the injector characteristic map, and an injection instruction signal having this pulse width PW is input to the electromagnetic solenoid of the injector 4. This will lift the core valve of the injector 4 only the pulse width PW (time width), and is configured so that the fuel injection according to the target injection amount Q _T is performed.

The minimum pulse width learning unit 12 learns the minimum pulse width PW _MIN of the injection instruction signal necessary for causing each injector 4 to start micro injection such as pilot injection. In the memory of the ECU 8, an integrated value (or peak value) of mechanical operating vibration generated when the injector 4 measured in advance by an experiment or the like starts fuel injection is stored as a determination threshold value _FTH .

When learning the minimum pulse width PW _MIN , for example, as shown in FIG. 3, first, at a predetermined common rail pressure A, each injector 4 is cycled with an injection instruction signal in which the pulse width PW is gradually increased from a very small width. (In the illustrated example, the first cycle is 0.1 msec, the second cycle is 0.2 msec, and the third cycle is 0.3 msec). When the integrated value (or peak value) F of the operating vibration detected by the vibration acceleration sensor 3 exceeds the determination threshold F _TH (F> F _TH ), the pulse width of the injection instruction signal output at this time (illustrated example) Then, the pulse width of the third cycle) is learned (stored in the memory of the ECU 8) as the minimum pulse width PW _MIN necessary for the start of minute injection (for example, pilot injection) at a predetermined common rail pressure A. Thereafter, the other common rail pressures B and C (see FIG. 2) are also configured to learn the minimum pulse width PW _{MIN in} the same procedure.

Even if the pulse width PW increased stepwise exceeds a predetermined upper limit width (for example, 1.0 msec), the integrated value (or peak value) F of the operating vibration detected by the vibration acceleration sensor 3 is the determination threshold value. If not exceeding F _TH, since the mechanical failure of the injector 4 can be considered, to prohibit learning of the minimum pulse width PW _MIN. In order not to affect the operation state of the diesel engine 1, learning of the minimum pulse width PW _MIN accompanying fuel injection is preferably performed only during no-load operation such as when the engine brake is operated.

The injector characteristic correction unit 13 corrects the injector characteristic map of each injector 4 based on the minimum pulse width PW _MIN learned by the minimum pulse width learning unit 12. For example, as shown in FIG. 3, 3 when the pulse width PW outputted to cycle the (0.3 msec) learned as the minimum pulse width PW _MIN, see injector characteristic map (FIG. 2 at this minimum pulse width PW _MIN ) Is corrected. Thereby, the control accuracy of the fuel injection in the micro injection region of the injection control unit 11 is improved, and a smaller amount of pilot injection becomes possible.

  In such a control device, the ECU 8 performs the processing described below with respect to the operating vibration of each injector 4 detected by the vibration acceleration sensor 3.

  In this example of processing, the case where the vehicle decelerates due to inertia traveling and the engine rotation speed gradually decreases is targeted, but the case where the vehicle speed increases on a downhill or the like is also targeted. The numerical values related to the engine rotation speed are typical examples, and are set as appropriate depending on the specifications and operating conditions of the diesel engine 1.

  First, when the ECU 8 detects from the signal value of the accelerator opening sensor 10 that the accelerator opening has become zero, the ECU 8 determines that the vehicle is in inertial traveling and inputs the signal value of the engine rotation sensor 9. .

  Next, the ECU 8 inputs the operation vibrations of the cylinders # 1 to # 4 when the engine rotation speed is 3000 to 2800 rpm from the vibration acceleration sensor 3 and averages them, and represents the engine rotation speed of 2900 rpm which is a median value. Learning as a drift value.

  Subsequently, the ECU 8 inputs the operation vibrations of the cylinders # 1 to # 4 when the engine rotation speed is 2800 to 2600 rpm from the vibration acceleration sensor 3 and averages them, and represents the engine rotation speed of 2700 rpm which is a median value. Learning as a drift value.

  By repeating the learning process as described above until the engine speed is reduced to 1000 rpm, map data indicating the relationship between the engine speed and the drift value is created. In addition, although the numerical range of the engine rotation speed at the time of inputting and averaging the operating vibration is set to 200 rpm in this example, it is not limited to this and may be further subdivided.

  This learning of the drift value is performed and completed before the above-described means for learning during deceleration (the pulse width is gradually increased). That is, the drift learning and the minimum injection pulse width learning are not performed simultaneously.

And the correction | amendment which deducts the drift amount is performed with respect to the operation vibration of the vibration acceleration sensor 3 detected according to the pulse width which increased gradually at the time of the driving | operation which learns the above-mentioned minimum injection pulse width. When this corrected value exceeds a preset threshold value (for example, determination threshold value F _TH ), it is determined that fuel has been injected, and the minimum injection pulse width is learned.

  By performing such processing, the influence of the change in the vibration state of the cylinder block 2 due to the difference in the engine rotation speed can be eliminated, so that the detection accuracy of the operation vibration is improved and the control result of the injection control is improved. It can be done.

  The object of the control device of the present invention is not limited to the fuel injection in the diesel engine 1, but is widely applied to the overall control of the operating state of the engine based on the operating vibration generated in the engine body. As such control, detection of misfire in cylinders # 1 to # 4, determination of misfire and premature ignition, and the like are preferably exemplified.

1 Diesel Engine 2 Cylinder Block 3 Vibration Acceleration Sensor 4 Injector 8 ECU
9 Engine rotation sensor 10 Accelerator opening sensor 11 Injection control unit 12 Minimum pulse width learning unit 13 Injector characteristic correction unit

Claims (2)

In an engine control device comprising: vibration detecting means for detecting an operating vibration generated in an engine body formed with a plurality of cylinders; and control means for controlling operation of the engine based on a detection value of the vibration detecting means.
The control means learns the amount by which the detected value drifts due to a difference in engine rotation speed in the engine body while the engine is traveling inertia, and then learns the minimum injection pulse width after the learning of the drift amount is completed. An engine control device that performs injection. The operation vibration generated in the engine body occurs when the injector performs fuel injection into the plurality of cylinders according to the pulse width of the input injection instruction signal.
Injection control means for controlling the fuel injection of the injector based on the injector characteristics indicating the relationship between the fuel injection amount stored in advance and the pulse width of the injection instruction signal;
An injection instruction signal whose pulse width is gradually increased from a minute width is output to the injector, and the operation vibration detected by the vibration detection means has a determination threshold value indicating the start of injection due to the operation of the injector stored in advance. If it exceeds, learning means for learning the pulse width output at this time as the minimum pulse width necessary for micro injection of fuel,
The engine control apparatus according to claim 1, further comprising: a correcting unit that corrects a pulse width corresponding to the minute injection amount of the injector characteristics with the learned minimum pulse width.

Images