JP4826220B2 - In-vehicle engine control system - Google Patents

Description

  The present invention relates to an in-vehicle engine control apparatus for suitably controlling generated torque when a vehicle starts.

  When a vehicle stopped on a hill starts, the vehicle may not start as intended by the driver, and problems such as deterioration of drivability may occur. Therefore, conventionally, an in-vehicle engine control device that performs engine control such as increasing the generated torque in order to stabilize the operation of the vehicle has been adopted.

  In addition, since the generated torque necessary for the vehicle to start varies according to the road surface gradient, the driver must perform delicate force adjustment operations to start the vehicle on a slope, such as depressing the accelerator pedal. Don't be. For this reason, when the vehicle starts on a slope, various techniques for keeping the operation of the vehicle stable have been proposed.

  For example, in Patent Document 1, when a vehicle stopped on an uphill starts, a road surface gradient is detected by a gradient sensor, and the fuel supply amount in an idle state is increased even if the driver does not depress the accelerator pedal. As a result, the unstable operation of the vehicle, which is likely to occur when the vehicle starts, can be suppressed, and the engine stop due to the burden on the engine can be avoided.

However, when a vehicle stopped on an uphill starts, the engine rotational speed in the idle state is increased regardless of the amount of depression of the accelerator pedal, and therefore engine control with respect to the road surface gradient and the traveling speed of the vehicle is not suitable. There seems to be something. In this case, the vehicle cannot start properly, and further, after the vehicle starts, a sense of incongruity due to a difference between the driver's sense of accelerator operation and the behavior of the vehicle that actually accelerates occurs, and drivability deteriorates.
JP 11-343888 A

  The present invention can properly start a vehicle on a slope, reduce a sense of incongruity due to a difference between the driver's sense of accelerator operation and the behavior of the vehicle after the start, and suppress deterioration in drivability. The main purpose is to provide a control device for an in-vehicle engine.

In the on-vehicle engine control device of the present invention, the engine control amount (the basic fuel injection amount of the engine) is calculated based on the accelerator operation amount by the driver, and the engine generation torque is controlled based on the engine control amount. To do.

  In particular, in the first aspect of the invention, the gradient calculating means calculates the road surface gradient by detection or estimation, and the correction amount calculating means calculates the gradient correction amount for the engine control amount based on the road surface gradient. The vehicle speed detecting means detects the traveling speed of the vehicle, and the correction amount correcting means corrects the gradient correction amount of the engine control amount in accordance with the change in the traveling speed of the vehicle. Then, the engine control amount is corrected by the corrected gradient correction amount.

The engine control amount is gradient-corrected based on the road surface gradient, and the generated torque is controlled based on the gradient-corrected engine control amount. As a result, it is possible to suppress the occurrence of problems such as the vehicle not starting as intended by the driver when the vehicle starts on a slope, and the vehicle can start properly. After the start of the vehicle, the gradient correction amount is corrected according to the changing vehicle speed, and the generated torque is controlled based on the engine control amount corrected by the corrected gradient correction amount. As a result, it is possible to alleviate the uncomfortable feeling caused by the difference between the driver's sense of accelerator operation and the behavior of the vehicle after the vehicle starts, and to suppress the deterioration of drivability.
Further, the correction amount calculation means calculates a positive gradient correction amount that corrects the engine control amount (the basic fuel injection amount of the engine) to the increase side when the road surface is uphill, and controls the engine when the road surface is downhill A negative gradient correction amount for correcting the amount to the decreasing side is calculated.
When the road surface is uphill, a reverse force is applied to the vehicle, and when the road surface is downhill, the vehicle is applied with a forward force. As a result, the vehicle becomes unstable. In this respect, in the present invention, by calculating the gradient correction amount of the engine control amount suitable for the road surface gradient, the generated torque control suitable for the vehicle start can be performed, and the vehicle can be started appropriately.

  By determining a reference speed for ending the engine control amount correction process, the engine control amount is corrected only in a speed region in which drivability deterioration is likely to occur in a vehicle started on a slope. When the vehicle speed reaches the reference speed, the gradient correction amount of the engine control amount is set to zero, so that the generated torque can be controlled continuously and smoothly. Therefore, torque shock can be reduced and drivability deterioration can be suppressed.

  By correcting the gradient correction amount based on the speed difference, the gradient correction amount is gradually reduced in accordance with a decrease in the speed difference as the vehicle speed increases. Further, since the speed difference immediately before the vehicle speed reaches the reference speed becomes zero after becoming small, the gradient correction amount is made zero after being made minute accordingly. For this reason, the gradient correction amount smoothly becomes zero, and it is possible to smoothly shift from the engine control amount in which the gradient correction is performed to the engine control amount in which the gradient correction is not performed.

According to a second aspect of the present invention, the on-vehicle engine control device includes a brake operation detecting means for detecting a brake operation by the driver. The gradient calculating means calculates the road surface gradient from the time required for the traveling vehicle to stop from the start of the brake operation and the vehicle speed at the start of the brake operation.

  When the running vehicle stops, the time until it stops depends on the road gradient. Further, the time required for the stop depends on the vehicle speed at the start of the brake operation. Therefore, the required time from the start of the brake operation to the stop and the vehicle speed at the start of the brake operation are used as calculation parameters, and the road surface gradient is estimated and calculated based on the calculation parameters. Thereby, even if it is a vehicle which is not equipped with a gradient sensor, a road surface gradient can be calculated. That is, the road surface gradient can be calculated using a general parameter that can be detected by a sensor or the like as a calculation parameter.

According to a third aspect of the present invention, the brake operation detecting means detects a brake operation amount, and the gradient calculating means uses a calculation parameter of a time required for the vehicle to stop from the start of the brake operation and a vehicle speed at the start of the brake operation. The road gradient is calculated by adding the operation amount.

  When a running vehicle stops, the time required from the start of brake operation to stop depends on the amount of brake operation in addition to the vehicle speed at the start of brake operation. The road slope can be calculated with high accuracy.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. The present embodiment embodies a control device for satisfactorily controlling the operating state of the engine when the vehicle starts on a slope with a diesel engine mounted on the vehicle as a control target. Is described below.

  FIG. 1 shows the overall configuration of the engine system. In FIG. 1, an engine system is mounted on a vehicle 10, and a multi-cylinder diesel engine (hereinafter referred to as an engine) 11 is provided with a fuel injection valve 12 for each cylinder, and fuel supplied from a fuel tank (not shown) is used for these fuels. The fuel is injected from the injection valve 12. Since the configuration of the engine 11 is well known, the detailed configuration of the engine 11 is not shown.

  This control device is provided with various sensors for detecting the state of the engine 11 and the vehicle 10. Specifically, an accelerator sensor 21 that detects an accelerator pedal operation amount (depression amount), a vehicle speed sensor 22 that detects a traveling speed of the vehicle 10, a brake sensor 23 that detects an operation of a brake pedal, and the like are provided.

  The ECU 20 is an electronic control unit mainly composed of a well-known microcomputer comprising a CPU, a ROM, a RAM, and the like. By executing various control programs stored in the ROM, the ECU 20 corresponds to the engine operating state each time. Various controls of the engine 11 are performed. That is, detection signals are input to the ECU 20 from the various sensors described above. The ECU 20 calculates an engine control amount based on various detection signals that are input as needed, and controls the generated torque of the engine 11 based on the engine control amount. In the present embodiment, the ECU 20 calculates a fuel injection amount based on an accelerator pedal operation amount by the driver as an engine control amount, and outputs an injection control signal corresponding to the fuel injection amount to the fuel injection valve 12. Control the generated torque. In this way, the ECU 20 performs fuel injection control from the fuel injection valve 12 to the engine 11.

  By the way, when the traveling vehicle 10 stops, the required time (hereinafter referred to as brake time) from the start of the depression operation of the brake pedal (hereinafter referred to as brake start) to the stop of the vehicle 10 changes according to the road gradient. . Also, the braking time varies depending on the vehicle speed at the start of braking. Therefore, in the present control device, the braking time and the vehicle speed at the start of braking are used as calculation parameters, and the road surface gradient is calculated based on the calculation parameters.

  The stopped vehicle 10 starts when the driver depresses the accelerator pedal. When the vehicle 10 starts uphill, a force in the backward direction works, and the required torque for the vehicle 10 to start is larger than when the vehicle 10 starts on a flat road surface. On the other hand, when the vehicle 10 starts on a downhill, a forward force acts, and the required torque for starting the vehicle 10 is smaller than when the vehicle 10 starts on a flat road surface. Therefore, the vehicle 10 stopped on the slope may not start properly. Therefore, it is conceivable to correct the fuel injection amount according to the road surface gradient. However, when the fuel injection amount is simply corrected according to the road surface gradient at the time of starting the vehicle, a sense of incongruity may occur due to a difference between the driver's feeling of depressing the accelerator pedal and the behavior of the vehicle that actually accelerates. .

  In other words, the fuel injection amount is corrected according to the road gradient at the time of starting the vehicle and immediately thereafter, so that the vehicle starts properly even if the driver performs the accelerator operation as usual regardless of the road surface gradient. If the vehicle speed increases to some extent, it is considered that the driver naturally performs the accelerator operation according to the road surface gradient. Therefore, there is a sense of incongruity due to the difference between the driver's feeling of depressing the accelerator pedal and the behavior of the vehicle that actually accelerates.

  Therefore, in the present control device, when the vehicle 10 stopped on the slope starts and after the start, the difference between the reference speed and the vehicle speed (hereinafter referred to as the speed), which is set in advance with the starting correction amount calculated based on the road gradient. The starting correction amount is gradually reduced according to the difference. At this time, by correcting the fuel injection amount according to the vehicle speed, it is possible to alleviate a sense of incongruity due to a difference between the driver's sense of depressing the accelerator pedal and the behavior of the vehicle. The reference speed is set to a speed within a speed region in which drivability is likely to deteriorate, for example, about 20 km / h.

  Next, the procedure of the road surface gradient calculation process executed by the ECU 20 will be described. FIG. 2 is a flowchart showing a road surface gradient calculation process.

  In FIG. 2, first, in step S101, it is determined whether or not the brake pedal of the traveling vehicle 10 is depressed. If the determination is NO, the present process is terminated as is. If the determination is YES, the process proceeds to step S102, and the vehicle speed detected by the vehicle speed sensor 22 at the start of braking is read. In step S103, the time elapsed from the start of braking is measured. Specifically, the elapsed time is counted by a gradient counter. The gradient counter is for calculating the road surface gradient from the count value.

  In step S104, it is determined whether the vehicle 10 has stopped. If the vehicle stops, the process proceeds to step S105, where the braking time and the vehicle speed at the start of the braking are read as calculation parameters. In the subsequent step S106, the road surface gradient is calculated from the calculation parameters read in step S105, and then this process is terminated. To do. If step S104 is NO, the process is terminated as it is.

  The above road surface gradient calculation processing will be described more specifically based on the timing chart of FIG. 3, (a) shows a change in brake pedal operation, (b) shows a change in speed until the running vehicle 10 stops, and (c) shows a change in gradient counter. A1, A2, and A3 indicate speed changes from the start of braking to the stop of the vehicle 10 traveling on an uphill, a flat road surface, and a downhill, respectively. The vehicle speeds at the start of these brakes are all the same.

  In the case of traveling uphill after operating the brake pedal, the vehicle stops at timing t1, and the value of the gradient counter at that time is C1. In the case of traveling on a flat road, the vehicle stops at timing t2, and the value of the gradient counter at that time is C2. In the case of traveling downhill, the vehicle stops at timing t3, and the value of the gradient counter at that time is C3.

  In this case, the value of the gradient counter when the vehicle is stopped corresponds to the brake time, and the brake time corresponds to the road surface gradient. In addition, the brake time varies depending on the vehicle speed at the start of the brake, and the brake time becomes longer as the vehicle speed is higher and shorter as the vehicle speed is lower. Accordingly, the road surface gradient can be calculated from the brake time and the vehicle speed at the start of the brake.

  The starting correction amount ΔQ0 is calculated based on the road surface gradient calculated from the braking time in this way. FIG. 4 shows the relationship between the road surface gradient and the starting correction amount ΔQ0. According to FIG. 4, the start correction amount ΔQ0 is increased to the positive side as the uphill gradient is increased, and the start correction amount ΔQ0 is increased to the negative side as the downhill gradient is increased. When the road surface is flat, the starting correction amount ΔQ0 is set to zero.

  FIG. 5 shows a flowchart of the slope start assist process. This processing is performed when the vehicle 10 stopped on a slope starts, and otherwise normal fuel injection amount control is performed without performing this processing.

  In FIG. 5, in step S201, the road gradient already calculated in the gradient calculation process is read. In step S202, it is determined whether or not the fuel injection amount needs to be corrected based on the road surface gradient. If the road surface is flat, a NO determination is made, and the present process ends. If the road surface is a hill, step S202 is determined as YES, the process proceeds to step S203, and the starting correction amount ΔQ0 is calculated based on the road surface gradient that has already been read. In step S204, the actual vehicle speed detected by the vehicle speed sensor is read.

  In step S205, a speed difference ΔSPD is calculated from the difference between the actual vehicle speed and the reference speed at that time (ΔSPD = reference speed−actual vehicle speed). In step S206, it is determined whether or not the speed difference ΔSPD is zero. In the case of YES determination, the present process is terminated as it is, and in the case of NO determination, the process proceeds to step S207, and the basic fuel injection amount Qbase is calculated based on the accelerator pedal operation amount by the driver. In step S208, the correction coefficient Ki is calculated based on the correction coefficient characteristics shown in FIG.

  According to FIG. 6, the correction coefficient Ki is calculated according to the speed difference ΔSPD. When the vehicle speed is zero, the speed difference ΔSPD is the same as the reference speed, and in that case, the correction coefficient Ki = 1. Then, the value of the speed difference ΔSPD is decreased and the correction coefficient Ki is decreased. When the vehicle speed reaches the reference speed, the speed difference ΔSPD is zero and the correction coefficient Ki is zero.

  In FIG. 5, in step S209, a correction correction amount ΔQi is calculated (ΔQi = Ki × ΔQ0). The correction correction amount ΔQi is obtained by correcting the starting correction amount ΔQ0 by the correction coefficient Ki. Finally, in step S210, a corrected fuel injection amount Qi is calculated (Qi = Qbase + ΔQi).

  FIG. 7 shows a timing chart of processing for correcting the basic fuel injection amount Qbase when the vehicle starts on an uphill. 7A shows a change in the operation of the accelerator pedal, FIG. 7B shows a change in the speed of the vehicle 10, and FIG. 7C shows a change in the fuel injection amount.

  At timing t10, the accelerator pedal is depressed (ON). At this time, the basic fuel injection amount Qbase indicated by the alternate long and short dash line has a magnitude based on the accelerator pedal operation amount, and the corrected fuel injection amount Qi indicated by the solid line is corrected by the start time correction amount ΔQ0. It becomes size. As the vehicle speed increases, the speed difference ΔSPD decreases. The correction correction amount ΔQi decreases according to the speed difference ΔSPD, and the correction fuel injection amount Qi gradually approaches the basic fuel injection amount Qbase.

  At timing t11, the vehicle speed reaches the reference speed, and the speed difference ΔSPD becomes zero. Further, the correction correction amount ΔQi becomes zero, and the correction fuel injection amount Qi becomes the same value as the basic fuel injection amount Qbase. For this reason, there is no quantitative step between the corrected fuel injection amount Qi and the basic fuel injection amount Qbase at the timing t11, and the correction of the basic fuel injection amount Qbase can be completed continuously and smoothly. Thereby, a torque shock can be reduced and deterioration of drivability can be suppressed.

  According to the embodiment described above in detail, the following excellent effects can be obtained.

  When the vehicle 10 starts on a slope, the basic fuel injection amount Qbase is corrected by the start correction amount ΔQ0 calculated based on the road surface gradient. Specifically, if the road surface is uphill, the basic fuel injection amount Qbase is corrected to the increase side, and if it is downhill, it is corrected to the decrease side. By correcting the basic fuel injection amount Qbase in this way, the generated torque can be suitably controlled according to the road surface gradient. Therefore, it is possible to suppress the occurrence of problems such as the vehicle 10 not starting as intended by the driver when the vehicle starts on a slope, and the vehicle 10 can be started properly.

  Further, the generated torque can be suitably controlled according to the vehicle speed by decreasing the starting correction amount ΔQ0 according to the increase in the vehicle speed. Thereby, after the vehicle 10 starts, the uncomfortable feeling due to the difference between the driver's sense of depressing the accelerator pedal and the behavior of the vehicle 10 can be alleviated, and deterioration of drivability can be suppressed.

  By reducing the correction coefficient Ki according to the decrease in the speed difference ΔSPD, the correction correction amount ΔQi decreases. When the speed difference ΔSPD becomes zero, the correction correction amount ΔQi becomes zero, and the correction fuel injection amount Qi becomes the same value as the basic fuel injection amount Qbase. Thereby, when the vehicle speed reaches the reference speed, the correction correction amount ΔQi can be made zero smoothly, so that the generated torque can be controlled continuously and smoothly. Therefore, torque shock can be reduced and drivability deterioration can be suppressed.

  Since the road surface gradient is calculated based on the brake time and the vehicle speed at the start of the brake, the road surface gradient can be calculated even for the vehicle 10 not equipped with a gradient sensor. That is, the road surface gradient can be calculated by using a parameter that can be detected by a sensor or the like mounted on the normal vehicle 10 as a road surface gradient calculation parameter.

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  In the above embodiment, the basic fuel injection amount Qbase is corrected by adding the starting correction amount ΔQ0 to the basic fuel injection amount Qbase. However, by changing this, the basic fuel injection amount Qbase is multiplied by a coefficient. The basic fuel injection amount Qbase may be corrected. For example, the correction coefficient Li is calculated based on the road surface gradient, and the correction coefficient Li is corrected according to the vehicle speed after the vehicle starts. Then, the basic fuel injection amount Qbase is corrected by the corrected correction coefficient Li, and the generated torque is controlled based on the corrected basic fuel injection amount Qbase. Accordingly, it is possible to further suppress the occurrence of inconvenience such as the vehicle 10 not starting as intended by the driver when the vehicle starts on a slope. And even after the vehicle starts, it is possible to alleviate the uncomfortable feeling caused by the difference between the driver's sense of accelerator operation and the behavior of the vehicle 10, and the drivability can be prevented from deteriorating.

  In the above embodiment, the relationship between the speed difference ΔSPD and the correction coefficient Ki is linear as in the correction coefficient characteristic of the basic fuel injection amount Qbase shown in FIG. 6, but the present invention is not limited to this. For example, when the speed difference ΔSPD is small, the degree of change of the correction coefficient Ki may be reduced, and when the speed difference ΔSPD is large, the degree of change of the correction coefficient Ki may be increased. As a result, when the vehicle speed approaches the reference speed, the change in the correction correction amount ΔQi corresponding to the change in the speed difference ΔSPD is reduced, and at the same time, the change in the corrected fuel injection amount Qi is reduced. Therefore, the generated torque can be controlled more smoothly when the vehicle 10 reaches the reference speed. Therefore, torque shock can be further reduced and drivability deterioration can be further suppressed.

  In the above embodiment, the road surface gradient is calculated from the braking time and the vehicle speed at the start of the brake operation. However, the road surface gradient may be calculated by changing this and adding the brake pedal operation amount to these calculation parameters. This is because the brake time varies depending on the road surface gradient and the vehicle speed at the start of the brake operation, and also varies depending on the brake pedal operation amount.

  FIG. 8 is a time chart showing changes in the vehicle speed depending on the brake pedal operation amount. In FIG. 8, (a) shows a change in the operation of the brake pedal, and (b) shows a change in the vehicle speed. When the brake operation amount is large (A21 in the figure) and the brake operation amount is small (A22 in the figure), the time from the start of braking until the vehicle stops (brake time) is different. Therefore, the road surface gradient can be calculated with higher accuracy by adding the brake pedal operation amount to the calculation parameter.

  Further, vehicle weight detection means (for example, a vehicle weight sensor) may be provided to detect the vehicle weight, and the vehicle weight detected by the vehicle weight detection means may be added to the road surface gradient calculation parameter. Further, a road surface state detection unit (for example, a raindrop sensor) for detecting a wet state of the road surface may be provided, and the road surface wet state detected by the road surface state detection unit may be added to the calculation parameter of the road surface gradient.

  In the above embodiment, the diesel engine mounted on the vehicle 10 is the control target. However, the gasoline engine mounted on the vehicle 10 may be controlled by changing this. In a gasoline engine, a required intake air amount is calculated based on an accelerator pedal operation amount, and a generated torque of the engine is controlled based on the required intake air amount. Therefore, the required intake air amount is corrected based on the road surface gradient, and the required intake air amount correction amount is corrected based on the vehicle speed. Thereby, even if it is the vehicle 10 by which the gasoline engine is mounted, the generation | occurrence | production torque can be controlled suitably at the time of the start on a slope.

It is a lineblock diagram showing an outline of an engine system in an embodiment of the invention. It is a flowchart which shows a road surface gradient calculation process. It is a time chart for demonstrating a road surface gradient calculation process. It is a figure which shows the relationship between a road surface gradient and the correction amount at the time of start. It is a flowchart which shows a slope start assistance process. It is a figure which shows the correction coefficient characteristic of the basic fuel injection amount. It is a time chart which shows a slope start assistance process. It is a time chart which shows the difference in the change of the vehicle speed by the amount of brake pedal operations.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11 ... Engine, 12 ... Fuel injection valve, 20 ... ECU, 22 ... Vehicle speed sensor, 23 ... Brake sensor.

Claims (3)

In the on-vehicle engine control device that calculates the basic fuel injection amount of the engine based on the accelerator operation amount by the driver and controls the generated torque of the engine based on the basic fuel injection amount.
A slope calculating means for calculating the road slope by detection or estimation;
Vehicle speed detecting means for detecting the traveling speed of the vehicle;
When the vehicle starts, based on the road surface gradient calculated by the gradient calculation means, if the road surface is an uphill, a gradient correction amount for correcting the basic fuel injection amount to the increasing side is calculated, and the road surface is a downhill vehicle. A correction amount calculating means for calculating a gradient correction amount for correcting the basic fuel injection amount to the decrease side,
Correction amount correction means for correcting the gradient correction amount according to a change in vehicle speed detected by the vehicle speed detection means,
The correction amount correcting means predetermines a reference speed within a speed region where drivability is likely to deteriorate , and reduces a speed difference that is a difference between the vehicle speed and the reference speed when the vehicle starts. Correspondingly, gradually with decreasing the gradient correction amount calculated by the correction amount calculating means, the gradient correction amount you modify the gradient correction amount so as to be zero when the vehicle speed reaches the reference speed control device for a vehicle-mounted engine, wherein the this. In the on-board engine control device provided with the brake operation detecting means for detecting the brake operation by the driver,
The vehicle-mounted vehicle according to claim 1 , wherein the gradient calculating means calculates the road surface gradient based on a time required for the traveling vehicle to stop from a brake operation start and a vehicle speed at the start of the brake operation. Engine control device. 3. The on-vehicle engine control device according to claim 2 , wherein the brake operation detecting unit detects a brake operation amount, and the gradient calculating unit adds the brake operation amount as a calculation parameter to calculate a road surface gradient.

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