JP3975524B2 - Vehicle driving force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a transient characteristic by setting a command value for constraining driving point, determining a transient value to be timewisely shifted of a driving force command value and a command value for constraining engine driving point and determining an engine torque command value and a gear ratio command value for making the command values follow actual values. SOLUTION: A driving force command value for speed control for matching actual speed with a speed command value is calculated in a speed control controller and this command value is distributed to an engine and a continuously variable transmission, during the driving of a vehicle. At this time, an estimation calculation D is performed for driving force and engine speed of an output of a control object to follow the command value. Next, a calculation E is performed for a second command value for constraining engine driving point based on an engine torque command value and an engine constraining condition and continuously, a calculation A is performed for a normative model characteristic for the driving force command value and the second command value. Further, an estimation calculation C is performed for engine speed and a gear ratio by using a linear model of the control object. Each command value of engine torque and the gear ratio is calculated from the above arithmetic results.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving force control device for a vehicle including a continuously variable transmission.
[0002]
[Prior art]
In a vehicle equipped with a continuously variable transmission, select a combination that can achieve optimal fuel consumption from the combination of engine torque and gear ratio that realizes the driving force to match the vehicle speed to its command value, and A driving force control method for controlling a transmission is known (see, for example, the Journal of the Society of Automotive Engineers of Japan (vol. 48, No. 10, 1994)).
According to this driving force control method, the optimum fuel efficiency driving characteristic of the engine is defined by the engine torque and the engine speed, and the horsepower command value is calculated from the driving force command value and the vehicle speed to obtain the horsepower command value on the optimum fuel efficiency driving line. The corresponding operating point is determined.
[0003]
[Problems to be solved by the invention]
However, since the conventional driving force control method considers only steady characteristics, the driving force command is affected by the delay between the engine torque control system and the transmission control system, and the inertia torque depending on the shift speed. There is a problem that the actual driving force does not follow quickly when the value changes. In particular, when downshifting or upshifting is performed in the positive driving force region, a phenomenon occurs in which the actual driving force once swings to the reverse side due to the influence of inertia torque as shown in FIG. Further, when downshifting or upshifting is performed in the negative driving force region (engine braking region), the actual driving force overshoots due to the influence of inertia torque as shown in FIG.
[0004]
An object of the present invention is to improve the response to a driving force command value.
[0005]
[Means for Solving the Problems]
(1) The invention according to claim 1 is a vehicle driving force control device for controlling the driving force of a vehicle including a continuously variable transmission, and is a driving force command value for normal travel according to an accelerator operation amount of a passenger. Or based on driving force command value determining means for determining a driving force command value for vehicle speed control for making the actual vehicle speed coincide with the vehicle speed command value, and an engine restraint condition considering the engine torque command value and optimum fuel consumption , An operating point restraining command value calculating means for calculating an engine speed command value for restraining the engine operating point, and a driving force command value and an engine when the driving force command value and the engine speed command value change Transient value determining means for determining a transient value of the rotational speed command value to be changed with time, rotational speed detecting means for detecting engine rotational speed, driving force detecting means for detecting driving force of the vehicle, and engine rotational speed Detection value and drive Calculation control means for calculating an engine torque command value and a gear ratio command value for matching the force detection value with the engine speed command value, the driving force command value, and their transient values , respectively, and an engine torque command value The engine drive control means for controlling the drive of the engine according to the above, and the continuously variable transmission drive control means for controlling the drive of the continuously variable transmission according to the gear ratio command value.
(2) The vehicle driving force control apparatus according to claim 2 includes vehicle speed detection means for detecting the vehicle speed, and the engine speed detection means and the driving force detection means include the engine torque command value, the transmission ratio command value, and the vehicle speed detection value. Based on the above, the engine speed and the driving force are estimated .
[0006]
【The invention's effect】
(1) According to the invention of claim 1, in addition to the driving force command value, the engine speed command value for constraining the operating point of the engine based on the engine torque command value and the engine restraint condition considering the optimum fuel efficiency. Is calculated, and a transient value to be temporally shifted between the driving force command value and the engine speed command value is determined, and an engine torque command value and a gear ratio command value for causing the actual value to follow these command values are determined. As a result, the drive control of the engine and continuously variable transmission is achieved, so that the desired driving force can be obtained and the transient characteristics when the driving force command value changes can be improved , thereby achieving the minimum fuel consumption performance. However, the responsiveness to the driving force command value can be improved.
(2) According to the invention of claim 2 , the engine speed and the driving force are estimated based on the engine torque command value, the gear ratio command value, and the vehicle speed detection value. Stability is not hindered by deterioration over time.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the configuration of an embodiment.
The set switch 1 is a switch for setting the current vehicle speed to the vehicle speed command value and starting the vehicle speed control. The acceleration switch 2 is a switch for increasing the set vehicle speed, and the coast switch 3 is a switch for reducing the set vehicle speed. The cancel switch 4 is a switch for canceling the vehicle speed control, and the brake switch 5 is a switch that operates when the foot brake is operated. When the brake switch 5 is actuated, the vehicle speed control is canceled in the same manner as when the cancel switch 4 is operated.
[0008]
The crank angle sensor 6 outputs a pulse train signal having a cycle proportional to the engine speed, and the vehicle speed sensor 7 outputs a pulse train signal having a cycle proportional to the vehicle speed. By measuring the period of these pulse train signals, the engine speed and the vehicle speed can be detected. The accelerator sensor 8 detects the opening of the accelerator pedal. This is used for normal control when the vehicle speed control is cancelled.
[0009]
The lean combustion engine 9 is controlled so that the engine torque matches the command value by intake air control by the throttle actuator 9a, fuel injection control by the injector 9b, and ignition timing control by the spark plug 9c. In the lean combustion engine 9, when the ideal air-fuel ratio (stoichiometric) state and the lean combustion air-fuel ratio state are switched as shown in FIG. The opening and closing timings of the intake and exhaust valves are discontinuously switched by switching the cam.
[0010]
The belt type continuously variable transmission 10 is controlled so that the gear ratio matches the command value by changing the radii of the primary pulley and the secondary pulley by hydraulic control. The belt type continuously variable transmission 10 includes a torque converter 11 with a lockup clutch for starting.
[0011]
Each of the vehicle speed control controller 12, the engine torque controller 13, and the transmission ratio controller 14 includes a microcomputer and its peripheral components, various actuator drive circuits, and the like, and communicates with each other via a communication circuit. The vehicle speed controller 12 performs setting and changing of the vehicle speed command value, calculation of a torque command value and a gear ratio command value, and the like. The torque controller 13 performs throttle opening degree control based on the engine torque command value of the engine 9 and switching control of engine operating states such as air-fuel ratio, intake / exhaust valve opening / closing timing, fuel cut / recovery, and the like. Further, the gear ratio controller 14 controls the gear ratio of the continuously variable transmission 10 based on the gear ratio command value.
[0012]
FIG. 4 is a flowchart showing a driving force control program. The operation of the embodiment will be described with reference to this flowchart.
The vehicle speed controller 12 executes this driving force control program every 10 ms, for example. In step 1, the accelerator opening is measured by the accelerator sensor 8, and in the subsequent step 2, the vehicle speed is measured by the vehicle speed sensor 7. In step 3, based on the measured accelerator opening, a normal driving force command value when the vehicle speed control is released is calculated. Specifically, a driving force characteristic that can realize an ideal acceleration feeling is stored in advance as a map, and a driving force command value corresponding to the accelerator opening measurement value is subjected to a table calculation.
[0013]
Further, in step 4, a driving force command value for vehicle speed control for making the actual vehicle speed coincide with the vehicle speed command value set by the occupant is calculated by a well-known PID control or robust control method. The vehicle speed control driving force command value includes a driving force command value for following the vehicle while maintaining a predetermined inter-vehicle distance from the preceding vehicle. In step 5, the normal driving force command value and the vehicle speed control driving force command value are compared, and the larger one is selected as the final driving force command value.
[0014]
In steps 6 to 10, a driving force distribution control calculation is performed by “model following control” which is one of multivariable control theories.
[0015]
FIG. 5 is a control block diagram for distributing the driving force command value to the engine 9 and the continuously variable transmission 10 and calculating the engine torque command value and the gear ratio command value. The driving force distribution control calculation will be described with reference to this control block diagram.
[0016]
In step 6, the driving force and the engine speed of the control target output to be made to follow the command value are estimated and calculated using the engine torque command value, the gear ratio command value and the vehicle speed, which are control target operation amounts (block) D). In this estimation calculation, a non-linear model to be controlled is used to increase calculation accuracy.
[0017]
In step 7, an engine operating point restraining second command value (engine speed command value) is calculated based on the engine torque command value that is the operation amount and the engine restraint condition (control block E). For example, as shown in FIG. 6, the engine restraint condition is determined by an optimal fuel efficiency operation line A, a fuel cut & throttle fully closed line B, and an engine speed limit line C (also depending on the vehicle speed). The optimum fuel consumption line A and the fuel cut & throttle fully closed line B are stored in advance as a map, and the operating point corresponding to the engine torque command value is calculated by a table calculation. However, it is limited by the upper and lower limits of the engine speed depending on the vehicle speed.
[0018]
In step 8, the normative model characteristic for the driving force command value and the second command value for restricting the engine operating point (engine speed command value) is calculated (control block A). In this embodiment, the reference model is composed of a simple digital filter such as a first-order lag, and the response to the driving force command value and the second command value for restricting the engine operating point (engine speed command value) is filtered. Adjust with a constant. Then, the normative model characteristics that should be changed with time in the driving force command value and the second command value for engine operating point restraint are set not only in the steady state but also in the transition time when the command value changes.
[0019]
In step 9, a state quantity used for state feedback, that is, an engine speed and a gear ratio are estimated and calculated using a linear model to be controlled (control block C).
[0020]
In step 10, the optimal regulator theory is applied to six variables including a state estimation value (engine speed, gear ratio), a reference model characteristic (driving force, engine speed), and an integrated value of output deviation (driving force, engine speed). Are multiplied by the state feedback gain matrix K derived from the above, and two operation amounts, that is, an engine torque command value and a gear ratio command value are calculated. That is, the driving force estimated value and the engine speed estimated value estimated by the control block D are changed to the driving force command value and the engine operating point restraining second command value (engine speed command value) calculated by the control block A. An engine torque command value and a gear ratio command value for matching are calculated.
[0021]
In step 11, the engine torque command value is output to the engine torque controller 13, and the gear ratio command value is output to the gear ratio controller 14.
[0022]
7 and 8 are diagrams showing the driving force control results according to the embodiment. FIG. 7 shows changes in the actual driving force, engine torque command value, and gear ratio command value when downshifting or upshifting is performed in the positive driving force region. FIG. 8 shows changes in actual driving force, engine torque command value, and gear ratio command value when downshifting or upshifting is performed in a negative driving force region.
As is clear from these driving force control results, when downshifting or upshifting as in the past, the actual driving force once swings to the opposite side and returns, and overshoot and undershoot do not occur. Responsiveness to changes in the driving force command value is improved.
[0023]
In this way, in addition to the driving force command value, the engine operating point constraint condition for realizing the optimum fuel efficiency is defined as the second command value, and the type 1 servo system (control system in which the steady deviation is 0) is configured. In a steady state, the driving force command value and the constraint condition can be achieved. Furthermore, because the driving force distribution control unit is designed using “model following control”, which is one of the multivariable control theories, it is possible to set the tracking performance to each command value relatively easily. is there. That is, since it is designed using a control target model that represents the influence of inertia torque, it is possible to cause the driving force to follow the command value in accordance with the preset reference model characteristics without being affected by the influence.
[0024]
Also, feed-forward control is performed using the value calculated by using the manipulated variable to the control target, without directly measuring the output or state quantity of the control target. Stability is not disturbed.
[0025]
In the above-described embodiment, the example in which the second command value for constraint condition (engine speed command value) is obtained based on the engine torque command value is shown. Conversely, the gear ratio command value (or engine speed) The second command value for constraint conditions (engine torque command value) may be obtained based on (numerical command value).
[0026]
In the above-described embodiment, the control block D uses the engine torque command value, the gear ratio command value, and the vehicle speed, which are manipulated variables, to estimate the driving force and the engine speed, which are outputs to be controlled. Although the engine speed is detected by the rotation sensor, the driving force may be calculated based on the detected engine speed and the engine torque command value of the operation amount.
[0027]
In the configuration of the above embodiment, the vehicle speed controller 12 is the driving force command value determining means, the transient value determining means, the rotation speed detecting means, the driving force detecting means and the arithmetic control means, and the engine controller 13 is the engine driving control means. The speed ratio controller 14 constitutes a continuously variable transmission drive control means, and the vehicle speed sensor 7 constitutes a vehicle speed detection means.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment.
FIG. 2 is a diagram showing switching between an ideal air-fuel ratio state and a lean combustion air-fuel ratio state.
FIG. 3 is a diagram illustrating switching between a low rotation cam and a high rotation cam.
FIG. 4 is a flowchart showing a driving force control program.
FIG. 5 is a control block diagram for distributing a driving force command value to an engine and a continuously variable transmission and calculating an engine torque command value and a gear ratio command value.
FIG. 6 is a diagram for determining engine restraint conditions.
FIG. 7 is a diagram illustrating a driving force control characteristic when downshifting or upshifting is performed in a positive driving force region by the driving force control apparatus according to the embodiment;
FIG. 8 is a diagram showing a driving force control characteristic when downshifting or upshifting is performed in a negative driving force region by the driving force control apparatus according to the embodiment;
FIG. 9 is a diagram showing a driving force control characteristic when downshifting or upshifting is performed in a positive driving force region by a conventional driving force control device.
FIG. 10 is a diagram showing a driving force control characteristic when downshifting or upshifting is performed in a negative driving force region by a conventional driving force control device.
[Explanation of symbols]
1 set switch 2 acceleration switch 3 coast switch 4 cancel switch 5 brake switch 6 crank angle sensor 7 vehicle speed sensor 8 accelerator sensor 9 lean combustion engine 9a throttle actuator 9b injector 9c spark plug 10 belt type continuously variable transmission 11 torque converter

Claims (2)

A vehicle driving force control device for controlling the driving force of a vehicle equipped with a continuously variable transmission,
A driving force command value determining means for determining a driving force command value for normal traveling according to the accelerator operation amount of the occupant, or a driving force command value for vehicle speed control for making the actual vehicle speed coincide with the vehicle speed command value;
Based on the engine torque command value described later and the engine restraint condition in consideration of the optimum fuel efficiency, operating point restraint command value computing means for computing an engine speed command value for restraining the engine operating point;
When the said driving force command value engine rotation speed command value is changed, the transient value determining means for determining a transient value to be temporally changes in the engine rotation speed command value and the driving force command value,
A rotational speed detecting means for detecting the engine rotational speed;
Driving force detecting means for detecting the driving force of the vehicle;
An engine torque command value and a gear ratio command value for making the engine speed detection value and the driving force detection value coincide with the engine speed command value, the driving force command value, and their transient values , respectively. Calculation control means for calculating;
Engine drive control means for controlling the drive of the engine according to the engine torque command value;
A vehicular driving force control device comprising: a continuously variable transmission drive control means for driving and controlling the continuously variable transmission according to the gear ratio command value. The vehicle driving force control device according to claim 1,
Vehicle speed detection means for detecting the vehicle speed,
The engine speed detecting means and the driving force detecting means estimate the engine speed and driving force based on the engine torque command value, the transmission ratio command value, and the vehicle speed detection value . Driving force control device.

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