JP2014237412A - Controller for engine surging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately adjust engine control parameters by accurately detecting an engine surging state without the influence of an irregularity situation of a road surface of a travel road.SOLUTION: A picked-up image is processed to detect an irregularity situation of a road surface of a travel road on which a vehicle travels, and it is determined whether the road surface is a surging triggering road surface from the detected irregularity situation of the road surface (S1, S2). If it is determined that the road surface is the surging triggering surface, a surging prevention control is exerted (S3) to adjust engine control parameters in advance so as to make occurrence of surging difficult. On the other hand, if it is determined that the road surface is not the surging triggering road, a rotational fluctuation amount of an engine is calculated and it is determined whether surging occurs by comparing the calculated rotational fluctuation amount with a threshold (S4, S5). If it is determined that surging occurs, a surging inhibiting process which inhibits surging is performed (S6). By doing so, it is possible to accurately detect a surging state of the engine and appropriately adjust the engine control parameters without influence of the irregularity situation of the road surface of the travel road.

Description

  The present invention relates to an engine surge control apparatus that detects a surge caused by engine combustion fluctuations and adjusts an engine control parameter.

  In general, in an engine mounted on a vehicle such as an automobile, a technique for improving fuel efficiency by EGR, lean burn, or the like is known. However, excessive EGR or excessive lean air-fuel ratio occurs due to individual differences of engines or changes over time. Then, combustion becomes unstable and vibration (surge) due to engine torque fluctuation occurs. Further, this engine surge is transmitted to the drive wheels via the drive system, and may cause rotational fluctuations of the drive wheels to cause longitudinal vibration (vehicle surge) of the vehicle body.

  For this reason, in Patent Document 1, during the steady operation, the difference in rotational fluctuation between the driving wheel and the non-driving wheel is calculated, and if this difference in rotational fluctuation is smaller than a predetermined value, the influence of the road surface When it is determined that the rotational fluctuation amount of the driving wheel is fluctuating, the detection of the vehicle surge level is prohibited. A technique is disclosed in which it is determined that the rotational fluctuation amount of the vehicle is fluctuating, and the level of the vehicle surge is detected based on the rotational fluctuation amount of the drive wheel, and control for suppressing the surge is performed.

JP 2007-113531 A

  However, the transmission of the rotational fluctuation amount between the engine and the tire is complicatedly related to individual differences such as the lock-up state of the automatic transmission, the gear ratio, the torsional characteristics of the drive system, and the backlash amount. It is difficult to accurately separate the engine surge and the vehicle body vibration due to the road surface condition only by detecting the rotational fluctuation amount of the drive system as in 1.

  For this reason, when the vehicle body vibration caused by the unevenness of the road surface is transmitted to the engine and the rotational fluctuation is generated, there is a risk of erroneously determining that the engine has generated a surge. If control parameters such as air-fuel ratio enrichment and ignition timing advance are adjusted, the control parameters are inappropriately adjusted, and the combustion state of the engine is worsened.

  The present invention has been made in view of the above circumstances, and is capable of accurately detecting engine surge conditions and appropriately adjusting engine control parameters without being affected by unevenness on the road surface of the traveling road. An object of the present invention is to provide a surge control device.

  An engine surge control apparatus according to the present invention is an engine surge control apparatus that detects a surge caused by engine combustion fluctuations and adjusts an engine control parameter, and detects a road surface shape detection that detects the undulation state of the road surface ahead of the host vehicle. And the road surface unevenness detected by the road surface shape detector, and based on the road surface unevenness, whether the road surface ahead of the host vehicle is a surge-induced road surface that induces a surge in the engine. A surge induction road surface determination unit that determines whether or not a surge induction road surface is determined by the surge induction road surface determination unit, a surge determination unit that determines whether or not a surge has occurred based on an index indicating an engine combustion fluctuation factor, A surge suppression control unit configured to adjust a control parameter of the engine to suppress the surge when the surge determination unit determines that a surge has occurred; Provided.

  According to the present invention, it is possible to accurately detect the surge state of the engine and appropriately adjust the engine control parameters without being affected by the unevenness of the road surface of the traveling road.

Overall configuration diagram of vehicle control system Explanatory drawing showing the monitoring area of the road surface condition Flow chart showing engine surge control processing

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an engine disposed in the front portion of the vehicle, and the driving force of the engine 1 is transmitted to a subsequent vehicle drive system via an automatic transmission 2 behind the engine 1. In the present embodiment, the automatic transmission device 2 includes a torque mechanism 3 that includes a clutch mechanism including a variety of hydraulic clutches and various hydraulic brakes for switching between forward and reverse, and a gear change, a planetary gear, and the like. An automatic transmission 5 having a main transmission mechanism is connected to the main transmission mechanism.

  The torque converter 3 includes a lock-up clutch 4 that engages the impeller and the turbine to transmit the driving force of the engine 1 directly to the automatic transmission 5. Further, the automatic transmission 5 is provided with a hydraulic control unit 5a integrally formed with various control valves for controlling the line pressure and pilot pressure to each mechanism unit.

  The driving force from the automatic transmission 5 is transmitted to the center differential device 6 and further inputted to the rear wheel final reduction device 10 via the rear drive shaft 7, the propeller shaft 8, and the drive pinion shaft portion 9, It is input to the front wheel final reduction gear 12 via the front drive shaft 11. The driving force input to the front wheel final reduction gear 12 is transmitted to the left front wheel 14FL via the front wheel left drive shaft 13FL, and is also transmitted to the right front wheel 14FR via the front wheel right drive shaft 13FR. On the other hand, the driving force input to the rear wheel final reduction gear 10 is transmitted from the rear wheel left drive shaft 15RL to the left rear wheel 16RL and from the rear wheel right drive shaft 15RR to the right rear wheel 16RR.

  Next, the vehicle electronic control system will be described. The vehicle electronic control system is configured by a plurality of control units connected to an in-vehicle network 100 formed via a communication bus such as a CAN (Controller Area Network). Each of the plurality of control units is configured around a microcomputer, and exchanges control parameter information based on various control information and signals from various sensors and switches via the in-vehicle network 100 to drive the vehicle. Control cooperatively.

  If it consists of such a plurality of control units, the electronic control system typically comprises an engine control unit (ECU) 50 for controlling the engine 1 and a transmission control unit (TCU) 60 for controlling the automatic transmission 2. Furthermore, a preview control unit (PCU) 70 is provided for acquiring driving environment information (preview information) outside the vehicle. The PCU 70 includes devices for sensing the environment outside the vehicle, such as a laser radar device, an ultrasonic sensor, and an image sensor.

  In the present embodiment, an imaging device is provided as an image sensor, and an image captured by the imaging device is processed to acquire driving environment information outside the vehicle. As the imaging device, a monocular camera or a stereo camera that captures an image of an object from different viewpoints can be used. In the following, the imaging device is composed of two cameras 80a and 80b having image sensors such as a CCD and a CMOS. The stereo camera 80 will be described as an example. The stereo camera 80 is mechanically fixed as a unit with a predetermined base line length (optical axis interval) so that the optical axes of the two cameras 80a and 80b are substantially parallel to each other. It is fixed and attached to.

  The ECU 50 includes a crank angle sensor 51 for detecting the crank angle provided on the outer periphery of the crank rotor 1a connected to the output shaft (crank shaft) of the engine, and an accelerator pedal depression amount (accelerator opening) of the driver. Signals from various sensors and switches such as an accelerator sensor 52 to detect and a vehicle speed sensor 53 to detect the speed of the vehicle are input. The ECU 50 controls the air-fuel ratio of the engine 1 (intake air amount control via an electronic control throttle, fuel injection control via an injector) based on information from these sensors and switches and control information from other control units. ), Engine control such as ignition timing control and EGR control is executed.

  The TCU 60 receives signals from various sensors and switches such as a shift position sensor 61 that detects the shift position of the automatic transmission 2 and a rotation sensor 62 that detects the rotation speed of the transmission output shaft. The TCU 60 controls the hydraulic pressure of the automatic transmission 2 via the hydraulic pressure control unit 5a based on information from these sensors and control information from other control units, and automatically shifts according to a preset shift characteristic. The apparatus 2 is controlled.

  In addition to the image signal from the stereo camera 80, various information such as the yaw rate, the vehicle speed, and the steering angle are input to the PCU 70 via the in-vehicle network 100. The PCU 70 processes the image captured by the stereo camera 80 to acquire distance information from the own vehicle to an object outside the vehicle, and this distance information and information from various sensors and switches input via the in-vehicle network 100. And the traveling environment ahead of the host vehicle is recognized based on the control information from the other control unit.

  In recognition of the environment outside the vehicle by the PCU 70, first, distance information is acquired from a stereo image captured by the stereo camera 80, and the environment outside the vehicle is recognized using this distance information. The distance information from the stereo image is obtained when one image (for example, the right image) of the pair of images captured in stereo is used as a reference image and the other image (for example, the left image) is used as a comparison image. For example, the image is divided into 4 × 4 pixel areas, and the luminance or color pattern of each area is compared with the comparison image to perform a matching process to search for the corresponding area. Obtained by determining the amount (parallax).

  From the pixel shift amount obtained by the stereo image matching process, an image (distance image) showing the distribution of distance information is generated, and the point on the distance image indicates the vehicle width direction of the host vehicle, that is, the left-right direction from the principle of triangulation. The coordinates are converted to a point in real space with the X axis, the vehicle height direction as the Y axis, and the vehicle length direction, that is, the distance direction as the Z axis. The PCU 70 recognizes a white line, a side wall, a three-dimensional object, etc. of the road ahead of the host vehicle based on the captured image and its distance information, assigns a different ID to each recognized data, and assigns each ID between frames. By continuously monitoring, traveling environment information in front of the host vehicle is acquired.

  Here, in the engine control by the ECU 50, a surge generated from torque fluctuation due to deterioration of the combustion state of the engine is detected, and control parameters such as an air-fuel ratio, an EGR amount, and an ignition timing are corrected according to the state of occurrence of the surge. By doing so, surge is suppressed. However, if vehicle body vibration due to the unevenness of the road surface on the road is transmitted to the engine via the drive system, and the engine fluctuation due to the transmitted vibration occurs, this is erroneously determined as a surge. there's a possibility that. If the control parameter of the engine is adjusted by erroneously determining that a surge has occurred, the adjustment of the control parameter is inappropriately performed, and conversely, the combustion state of the engine is worsened.

  For this reason, in the present embodiment, as in the prior art, a surge control device that determines and controls the surge of the engine by adding the PCU 70 without determining and controlling the surge only by the ECU 50 (or the ECU 50 and the TCU 60). Is configured. Prior to the engine surge determination by the ECU 50, the PCU 70 detects the road surface unevenness from the image of the road ahead of the host vehicle imaged by the stereo camera 80, and determines whether the road surface is a road surface (surge-induced road surface) that induces a vehicle surge. Determine. When it is determined by the PCU 70 that the road surface is not a surge-induced road surface, the ECU 50 performs engine surge determination and adjusts engine control parameters according to the determination result.

  When the PCU 70 determines that the road surface is a surge-induced road surface, that is, when it is predicted that the vibration transmitted from the road surface through the drive system by driving on the uneven road surface will induce an engine surge, the ECU 50 Adjusts the control parameters of the engine in a direction in which a surge is unlikely to occur in advance to prevent a surge from being generated due to running on an uneven road surface.

  As shown in FIG. 1, as a function related to surge detection, the PCU 70 includes a road surface shape detection unit 90 that detects road surface undulation (unevenness) from image data in front of the host vehicle imaged by the stereo camera 80, a road surface A surge-induced road surface determination unit 91 is provided for determining whether the road surface is a surge-induced road surface that induces a vehicle surge from the uneven state. Further, when it is determined that the road surface is not a surge-induced road surface, the ECU 50 suppresses the surge or prevents the occurrence of the surge by adjusting the engine determination parameter 92 for determining whether or not the engine has a surge. A surge controller 93 is provided.

  Specifically, the surge control unit 93 adjusts the engine control parameters to suppress the surge when it is determined that a surge has occurred, and the surge control unit 93a determines that it is a surge-induced road surface. A surge prevention control unit 93b that preliminarily adjusts control parameters of the engine so as not to occur easily is configured. The surge inducing road surface determination unit 91 may be provided as a functional unit of the ECU 50 or the TCU 60.

  Detection of the road surface unevenness by the road surface shape detection unit 90 acquires data such as the position, height (depth), and shape of the road surface unevenness based on the three-dimensional information obtained by processing the stereo image. . The height information of each point on the road surface can be calculated, for example, by estimating a plane from a stereo image and using the plane as a reference. At this time, when information such as the center line, white line, road sign, etc. of the road surface recognized from the image can be used, the measurement accuracy of the road surface shape can be improved by using these information.

  When calculating height information using the estimated plane as a reference, extract at least three feature points on the road surface in the image, and coordinate the feature points in real space using the principle of triangulation from the parallax of each feature point A value is obtained, and a plane equation is calculated using a statistical process such as a least square method or a Hough transform. Then, the distance between the reference plane indicated by the plane equation and each point is calculated as the height of each point on the road surface.

  Note that the height of each point on the road surface can be detected without using a stereo image, for example, by recognizing a luminance distribution of an image obtained by imaging the road surface or a projection pattern projected onto the road surface. In addition, the height of each point on the road surface may be detected by a road surface sensor using ultrasonic waves or infrared rays without using an image from the camera, and the slip generation interval calculated from the difference between the vehicle speed and the wheel speed. It is also possible to calculate the height of each point on the road surface. Furthermore, when it is possible to acquire road gradient and unevenness information from the navigation device, these information may be used.

  Surge-induced road surface determination unit 91 is a road surface on which the vehicle will travel from now on, such as unpaved rough terrain, gravel roads, rough roads, etc. It is determined whether or not (surge-induced road surface). Specifically, a road surface monitoring area is set on the road surface ahead of the host vehicle, and the amount of variation with respect to the average height of each point in the monitoring area is calculated as the road surface unevenness degree. The surge-induced road surface is determined from the degree.

  For example, as shown in FIG. 2, the traveling path P of the host vehicle C is estimated based on the yaw rate, the vehicle speed, the steering angle, and the like, and the forward position separated by a set distance (for example, several meters) along the traveling path P In addition, a monitoring area R having a predetermined area in consideration of the size of the host vehicle and the vehicle speed is set. The monitoring region R is set by changing its position dynamically as the host vehicle C moves.

  In addition, as shown with a broken line in FIG. 2, when a travel lane can be recognized from the white line etc. of a road surface, you may make it set a monitoring area | region with respect to this travel lane.

  Further, the surge inducing road surface determination unit 91 obtains an average height by averaging the heights of the points in the monitoring region R, and examines variations in the heights of the points with respect to the average height. Then, the standard deviation σh in the height distribution of each point is calculated as the road surface unevenness degree (road surface height fluctuation amount), and compared with a preset threshold value Hd1. The threshold value Hd1 is a road surface height fluctuation amount that induces a surge by vibrations transmitted from the road surface to the engine via the drive system, and is set in advance through experiments or simulations in consideration of vehicle characteristics.

  As a result of the comparison between the road surface unevenness degree σh and the threshold value Hd1, when the state of σh ≧ Hd1 continues for a set time or more, it is determined that the road surface ahead of the host vehicle is a surge-induced road surface. In addition, in order to deal with the case where there is a large unevenness locally on the road surface, if a state exceeding the threshold value Hd1 and exceeding the threshold value Hd2 (Hd2> Hd1) is experienced, the range of the set distance (time) thereafter is also set. Judged as a surge-induced road surface.

  The surge determination unit 92 determines the presence or absence of occurrence of a surge based on various fluctuation factors generated due to a surge, such as engine combustion pressure fluctuation and rotation fluctuation. The surge determination in the surge determination unit 92 is performed only when the surge induction road surface determination unit 91 does not determine the surge induction road surface, that is, when there is no possibility that a surge is induced in the engine due to vibration from the road surface. In the present embodiment, a variation amount (rotational variation amount) ΔNe of the engine speed Ne based on a signal from the crank angle sensor 51 is used as an index indicating an engine combustion variation factor for determination.

  The surge determination unit 92 compares the rotation variation amount ΔNe with the surge determination threshold value Hs, and determines that no surge has occurred when the rotation variation amount ΔNe is equal to or less than the surge determination threshold value Hs, and the rotation variation amount ΔNe is determined as a surge determination. When the threshold value Hs is exceeded, it is determined that a surge has occurred. In this embodiment, the surge determination threshold value Hs is set at least according to the lockup state by the lockup clutch 4 of the automatic transmission 2 and further set in advance for each gear stage (gear ratio) of the automatic transmission 5. Has been.

  When the lock-up clutch 4 is slip-controlled in the releasing direction, the vibration transmitted from the road surface to the engine via the drive system is attenuated by the torque converter 3, so that the surge determination threshold value Hs is relatively small. Is set to the direction. Further, since the influence of vibration transmitted from the road surface via the drive system on the engine becomes smaller as the transmission gear ratio becomes larger, the surge determination threshold value Hs is set to be relatively smaller.

  When the surge determination unit 92 determines that a surge has occurred, the surge suppression control unit 93a controls the engine such as the EGR amount, the air-fuel ratio, and the ignition timing until the fluctuation of the engine speed reaches a level at which the surge determination is canceled. Adjust the parameters. For example, when adjusting the EGR amount, the surge is suppressed by reducing the EGR amount and stabilizing the combustion, and when adjusting the air-fuel ratio and ignition timing, the fuel injection amount is corrected to be increased. By enriching the air-fuel ratio and advancing the ignition timing, the engine torque is increased and surge is suppressed.

  On the other hand, the surge prevention control unit 93b is unlikely to generate a surge when the surge induction road surface determination unit 91 determines that it is a surge induction road surface, that is, when there is a possibility that a surge is induced in the engine due to vibration from the road surface. As described above, the control parameters of the engine are adjusted in advance preventively. The adjustment of the control parameter by the surge prevention control unit 93b is a gradual adjustment with respect to the adjustment of the control parameter by the surge suppression control unit 93a. For example, the amount of EGR reduction, the degree of air-fuel ratio enrichment, and the ignition timing advance amount Is adjusted in a smaller direction.

  Next, surge control processing by the PCU 70 and the ECU 50 will be described using the flowchart of FIG.

  The first steps S1 and S2 in this surge control process indicate the process in the PCU 70, and the steps after S3 indicate the process in the ECU 50. First, in the first step S1, an image picked up by the stereo camera 80 is processed to detect the unevenness state of the road surface of the vehicle traveling road (road surface shape detection unit 90). In the following step S2, it is determined whether or not the road surface is a surge-induced road surface from the detected uneven surface condition (surge-induced road surface determination unit 91).

  As a result, if it is determined that the road surface is a surge-induced road surface, the process proceeds from step S2 to step S3 to implement surge prevention control (surge prevention control unit 93b), so that the engine control parameter is less likely to generate a surge. Adjust in advance. On the other hand, if the road surface is not a surge-induced road surface, the process proceeds from step S2 to step S4 and subsequent steps to make a surge determination (surge determination unit 92), and when it is determined that a surge has occurred, a surge suppression process is performed to suppress the surge (surge suppression). Control unit 93a).

  Specifically, in step S4, the rotational fluctuation amount ΔNe is calculated from the signal of the crank angle sensor 51, and in step S5, the rotational fluctuation amount ΔNe is compared with the surge determination threshold value Hs. As a result, in the case of ΔNe ≦ Hs, it is determined that no surge has occurred and the present process is exited. In the case of ΔNe> Hs, it is determined that a surge has occurred and the surge suppression control is performed in step S6, and the EGR amount Surge is suppressed by reduction, enrichment of air-fuel ratio, ignition timing advance, etc. This surge suppression control is continued until ΔNe ≦ Hs.

  As described above, in the present embodiment, it is determined whether or not the road surface is a road surface that induces a surge by detecting the unevenness of the road surface ahead of which the host vehicle will travel, and it is determined that the road surface is not a surge-induced road surface. Only do engine surge judgment. This makes it possible to accurately detect the surge state of the engine without being affected by the unevenness of the road surface of the traveling road, and appropriately adjust the engine control parameters to suppress the surge and prevent deterioration of fuel consumption. be able to. In addition, if it is determined that the road surface is a surge-induced road surface, it is possible to prevent the occurrence of a surge by adjusting the engine control parameters in advance to avoid the deterioration of the combustion state of the engine, thereby preventing the deterioration of fuel consumption. In addition, it is possible to prevent the drivability from deteriorating.

  In the present embodiment, the rotational fluctuation amount ΔNe is calculated from the signal of the crank angle sensor 51, and it is determined whether or not a surge has occurred based on the rotational fluctuation amount ΔNe. The method is not limited to this. For example, the standard deviation σ of the engine speed Ne is calculated based on a signal from the signal of the crank angle sensor 51, and it is determined whether or not a surge is generated based on the standard deviation σ. A known method may be applied.

DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Torque converter 4 Lock-up clutch 50 Engine control unit 60 Transmission control unit 70 Preview control unit 80 Stereo camera 90 Road surface shape detection part 91 Surge induction road surface determination part 92 Surge determination part 93 Surge control part 93a Surge suppression Control unit 93b Surge prevention control unit Hd1, Hd2 threshold Hs surge judgment threshold R monitoring area σh degree of road surface unevenness

Claims (5)

In an engine surge control device that detects a surge caused by engine combustion fluctuations and adjusts an engine control parameter,
A road surface shape detection unit for detecting the undulation state of the road surface ahead of the host vehicle;
The road surface unevenness degree is calculated from the road surface undulation state detected by the road surface shape detection unit, and based on the road surface unevenness degree, it is determined whether the road surface ahead of the host vehicle is a surge-induced road surface that induces a surge in the engine. A surge-induced road surface determination unit;
If the surge-induced road surface determination unit is not determined to be a surge-induced road surface, a surge determination unit that determines the presence or absence of occurrence of a surge based on an index indicating an engine combustion fluctuation factor;
A surge suppression device for an engine, comprising: a surge suppression control unit that adjusts an engine control parameter to suppress the surge when the surge determination unit determines that a surge has occurred.   A surge prevention control unit that adjusts the engine control parameters in advance in a direction in which a surge is unlikely to occur before the vehicle passes the forward surge induction road surface when the surge induction road surface determination unit determines that it is a surge induction road surface; A surge control device for an engine, further comprising:   The surge-induced road surface determination unit sets a road surface state monitoring area on the road surface in front of the host vehicle, calculates a fluctuation amount with respect to the average height of each point in the monitoring area as a road surface unevenness degree, and calculates the road surface unevenness degree. The engine surge control device according to claim 1 or 2, wherein it is determined whether or not the surface is a surge-induced road surface by comparing with a preset threshold value.   The surge determination unit compares the index indicating a combustion variation factor of the engine with a surge determination threshold set according to at least a lock-up state of the automatic transmission, and when the index exceeds the surge determination threshold, The engine surge control apparatus according to any one of claims 1 to 3, wherein it is determined that a surge has occurred.   The road surface shape detection unit detects the undulation state of the road surface based on three-dimensional information obtained by processing a stereo image captured by a vehicle-mounted camera. The engine surge control device described.

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