JP2805061B2 - Control system for vehicle drive train - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a vehicle drive system, and more particularly, to an engine having means capable of changing engine torque independently of an accelerator opening and a speed ratio. The present invention relates to an improvement of a control device for a vehicle drive system including a continuously variable transmission capable of continuously controlling the vehicle. 2. Description of the Related Art As one of automatic transmission mechanisms for vehicles, there is a continuously variable transmission mechanism driven by a belt or the like. This continuously variable transmission mechanism generally has, on an input shaft and an output shaft, a V-type pulley device comprising a fixed pulley and a movable pulley, the effective diameter of which is variable by a hydraulic servo device. The rotation of the input shaft side can be transmitted to the output shaft side by changing the speed in a stepless manner by the transmission belt stretched therebetween. Usually, the flow rate of the oil to the input side hydraulic servo device is changed by a flow control valve to forcibly change the effective diameter of the input side V-type pulley device, while the hydraulic pressure of the output side hydraulic servo device is changed. The torque is changed by the pressure control valve so that the transmission belt can transmit torque without slipping following the change of the effective diameter of the input-side V-shaped pulley device. When such a continuously variable transmission mechanism is introduced in the drive system of the vehicle, the vehicle can always be driven on the optimal fuel consumption line in the engine use area, and the fuel efficiency of the actual vehicle can be improved. However, the fact is that any of the techniques disclosed in the related art still has room for improvement. For example, Japanese Patent Application Laid-Open No. 59-32642 discloses a method in which an engine is always operated on an optimum fuel efficiency line even during a transition in running a vehicle. However, in this method, output torque is insufficient during a shift transition. Therefore, there is a problem that running performance, especially acceleration performance, is deteriorated. In Japanese Patent Application Laid-Open No. 58-39870, the vehicle travels on the optimal fuel consumption line in a steady state, while the shift response of the continuously variable transmission mechanism is slower than that of the throttle actuator during the shift transition. The operation shown by the dashed line in the figure results in a departure from the optimum fuel economy line and the running performance is reduced as described in
A method is disclosed that is superior to -32642.
However, this method results in the operation as shown by the broken line in FIG. 6 during the shift transition, and cannot control the output during the shift transition arbitrarily. On the other hand, in Japanese Patent Application Laid-Open No. 58-160661, in claim 6, an engine torque that achieves a target output horsepower at an actual engine rotation speed is defined as a target engine torque. A method of performing feedback control is disclosed. According to this method, the output can be set to a predetermined value during a shift transition. However, the "engine torque to achieve the target output horsepower" set in Japanese Patent Application Laid-Open No. 58-160661 was set only on the optimal fuel consumption line, that is, it is assumed that the minimum fuel consumption rate is achieved. Therefore, the target value to be set at the time of shift transition is not always appropriate, and there is a problem that the driver's acceleration demand cannot be sufficiently satisfied. SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has as its object to provide a control device for a vehicle drive system capable of achieving both excellent fuel efficiency and good running characteristics. Aim. Means for Solving the Problems The first invention comprises an engine having means for changing the engine torque independently of the accelerator opening, and a continuously variable transmission capable of continuously controlling the speed ratio. Means for determining a target output horsepower based on the accelerator opening, means for determining an actual rotational speed of the engine, and an engine for operating the engine near an optimal fuel economy line. Means for determining the torque as a basic target engine torque based on the determined actual engine rotational speed; and setting the target output horsepower or a required engine torque for achieving the target output horsepower as a target output value, Means for detecting a difference between the target output value and an actual output value corresponding to the target output value; and a means for detecting the basic target engine torque based on the difference between the target output value and the actual output value. Means for determining the correction value, the means for calculating the sum of the basic target value and the correction value, and the means for changing the engine torque using the obtained sum as the final target engine torque. And means for performing feedback control so that the engine torque and the engine torque coincide with each other. According to a second aspect of the present invention, there is provided a control system for a vehicle drive system including an engine having means for changing an engine torque independently of an accelerator opening and a continuously variable transmission capable of controlling a speed ratio in a stepless manner. Means for determining the target drive torque based on the accelerator opening, means for determining the actual rotational speed of the engine, and engine torque for operating the engine near the optimal fuel economy line as a basic target engine torque. Means for determining based on the determined actual engine rotation speed, and the target output horsepower or the required engine torque for achieving the target drive torque as a target output value, the target output value and the target output value Means for detecting a difference between the corresponding actual output value, and means for determining a correction value for the basic target engine torque based on the difference between the target output value and the actual output value. Means for calculating the sum of the basic target engine torque and the correction value; and means for changing the engine torque using the obtained sum as the final target engine torque. And a means for controlling the feedback as described above. According to the first aspect of the present invention (the first aspect of the present invention), the target output horsepower (which is considered to be desired by the driver) is determined based on the accelerator opening and the engine is operated. First, the engine torque for driving near the optimal fuel efficiency line is determined based on the actual engine speed as the basic target engine torque, while achieving the target output horsepower or the target output horsepower determined based on the accelerator opening. The required engine torque for performing this operation is defined as a “target output value”, and the actual output value corresponding to the target output value (the actual output horsepower when the target output value is the target output horsepower, and the actual output horsepower when the target output value is the required engine torque). A difference (deviation) from the target engine torque is detected, and a correction value of the basic target engine torque is determined based on the difference between the target output value and the actual output value. Then, a "sum" of the basic target engine torque and the correction value including the concept of the difference is obtained, and the obtained "sum" is used as a final target engine torque, and by means capable of changing the engine torque. Feedback control is performed so that the actual engine torque becomes the target engine torque. Therefore, the engine is controlled based on the target value obtained based on the optimal fuel efficiency line when the vehicle is running close to the so-called steady state, and when the traveling state becomes more transient, the driver's request is made. The target value itself can be continuously varied and controlled in consideration of the output value to be performed and the actual output value. Therefore, it is possible to satisfactorily achieve both improvement in fuel efficiency and improvement in power characteristics. When a target value (which is considered to be desired by the driver) is determined in accordance with the accelerator opening, the target value is not set to the "target output horsepower" as described above but to the "target (vehicle)". It is also possible to use "drive torque". Also in this case, the same function and effect can be obtained (second invention: Claim 2). Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows an overall outline of an automobile engine and a continuously variable transmission to which an embodiment of a vehicle drive system control device according to the present invention is applied. In the figure, an output shaft 2 of an engine E / G is connected to a belt-driven continuously variable transmission (hereinafter referred to as CVT) via a clutch mechanism 4. The CTV includes V-type pulley devices 10 and 14 including fixed pulleys 11 and 15 and movable pulleys 12 and 16 on an input shaft 6 and an output shaft 8, respectively. Input side fixed pulley 11 is input shaft 6
The input side movable pulley 12 is fitted to the outer periphery of the input shaft 6 by a spline or a ball bearing or the like so as to be movable in the axial direction. Similarly, the output-side fixed pulley 15 is
The output side movable pulley 16 is fitted to the outer periphery of the output shaft 8 by a spline or a ball bearing so as to be movable in the axial direction. The pressure receiving areas of the movable pulleys 12 and 16 are set so that the input side is greater than the output side, so that the effective diameter can be forcibly changed for changing the speed ratio on the input side. In addition, the arrangement of the fixed pulleys 11 and 15 and the movable pulleys 12 and 16 in the axial direction on the input side and the output side is reversed with each other, so that the transmission belt 18 always enters, and the transmission belt 18 hangs at right angles to the output shafts 6 and 8. It is. The opposing surfaces of the fixed pulleys 11 and 15 and the movable pulleys 12 and 16 are formed on tapered surfaces that increase the distance from each other in a radially outward direction. A transmission belt 18 with a trapezoidal cross section
Is hooked between the V-type pulley devices 10 and 14 on the input side and the output side. In the power transmission belt 18, the radial contact position on the pulley surface continuously changes as the V-type pulley devices 10 and 14 are fixed and the tightening force of the movable pulley changes. Input side V
When the contact position of the transmission belt 18 in the pulley device 10 moves outward in the radial direction, the contact position of the transmission belt 18 in the output V-type pulley device moves inward in the radial direction, and the CVT
Speed ratio e (= rotation speed Nout of output shaft 8 / rotation speed Nin of input shaft 6) increases, and conversely, speed ratio e decreases. The power of the output shaft 8 is transmitted to the drive wheels via a planetary gear unit for switching between forward and backward movement, a gear unit for reduction, a differential gear unit, and the like (not shown). On the other hand, the accelerator pedal sensor 34 detects the opening degree θac of the accelerator pedal 36 depressed by the driver's foot 35.
The opening of the intake throttle of the engine E / G is controlled by a throttle actuator 19 independent of the accelerator pedal 36. The input-side and output-side rotation angle sensors 20 and 21 detect the rotation angles of the pulleys 11 and 16, respectively. As a result, the rotation speed (the vehicle speed V from the output-side rotation speed) is detected and converted. The pressure control valve 24 controls the line pressure PL of the oil passage 29 by controlling the amount of oil as a hydraulic medium sent from the reservoir 26 via the oil passage 27 to the oil passage 28 by the oil pump 25. Regulate pressure. The line pressure PL is supplied to the hydraulic servo device of the output side movable pulley 16 via an oil passage 29. The flow control valve 30 controls the amount of oil flowing into and out of the input-side movable pulley 12. In order to maintain the speed ratio e of the CVT constant, a line pressure oil passage branched from the oil passage 33 and the oil passage 29 is required.
The connection with 31 and the drain oil passage 32 is disconnected. As a result, the position of the input side movable pulley 12 in the axial direction is kept constant, and the speed ratio e is also kept constant. Further, in order to increase the speed ratio e, oil is supplied from the line pressure oil passage 31 to the hydraulic servo device of the input side movable pulley 12 via the oil passage 33. As a result, the tightening force between the input pulleys 11 and 12 is increased, and the transmission belt on the input pulleys 11 and 12 faces.
The contact position 18 moves radially outward, and the speed ratio e is increased. Conversely, in order to reduce the speed ratio e, the oil in the hydraulic servo device of the input side movable pulley 12 is
It is connected to the atmosphere side via 32 to reduce the tightening force between the input side pulleys 11 and 12. Although the oil pressure in the oil passage 33 is equal to or less than the line pressure PL, as described above, the piston pressure receiving area of the hydraulic servo device of the input side movable pulley 12 is set to be larger than the piston pressure receiving area of the hydraulic servo device of the output side movable pulley 16. Therefore, the tightening force of the input pulleys 11 and 12 can be made larger than the tightening force of the output pulleys 15 and 16. The effective diameter between the input pulleys 11 and 12 is changed by changing the tightening force of the input pulleys 11 and 12 by the flow control valve 30, while the effective diameter of the input pulleys 15 and 16 on the input side is changed. The line pressure PL is regulated by the pressure control valve 24 so as to generate a tightening force following the diameter change so that the transmission belt 18 does not slip and the torque transmission is secured. The electronic control unit 38 includes a D / A converter 40, an input interface 41, an A / D converter 42, a CPU 43, a RAM 44, and a ROM 45, which are connected to each other by an address data bus 39. The analog output θac of the accelerator pedal sensor 34 is
The pulses are sent to the A / D converter 42 and the pulses of the rotation angle sensors 20 and 21 are sent to the input interface 41. Control voltages Vth, Vin, and Vout to the throttle actuator 19, the flow control valve 30, and the pressure control valve 24 are sent from the D / A converter 40 via amplifiers 49, 50, and 51, respectively. The throttle actuator 19 is controlled in accordance with the change in the input voltage to the amplifier 49, so that the intake throttle opening changes. Further, the flow control valve 30 is controlled in accordance with the change in the input voltage to the amplifier 50, so that the flow of the movable pulley 12 to the input hydraulic servo changes. As a result, the speed ratio e changes in accordance with the change in the input current of the amplifier 50. Further, the force control valve 24 is controlled in accordance with a change in the input voltage to the amplifier 51, so that the line pressure PL changes. Filed even line pressure PL input current is zero the pressure control valve 24 is summer so as to maintain a predetermined value PL _1, even when event defective disconnection or the electronic control unit 38, the movable pulley 12, The predetermined hydraulic pressure is supplied to the 16 hydraulic servos, and the minimum torque transmission in the CVT is ensured. FIG. 3 is a block diagram of a control system of the apparatus. In the figure, a block 100 indicates a computing unit for obtaining the target output horsepower PS ゜ from the accelerator opening θac and the vehicle speed V by an equation or a map in a known manner. A block 102 indicates an arithmetic unit for obtaining a target input side rotational speed Nin # from a target output horsepower PS #. This method is set, for example, to the optimum fuel penetration line A as shown in FIG. In FIG. 5, the solid line is the constant fuel efficiency rate line (g /
PS · H), and the dashed line indicates the equal horsepower factor line (PS). The block 104 controls the CVT speed ratio e by feedback-controlling the control voltage Vin of the flow control valve 30 so that the actual input-side rotation speed Nin of the CVT becomes the target input-side rotation speed Nin ゜. Is shown. For this control, for example, an arithmetic expression such as Expression (1) is used. Vin = k ₁ (Nin−Nin ゜) (1) In this control, it is free to make a correction according to, for example, the oil temperature or the like, and use a more accurate arithmetic expression. A block 106 indicates a calculator for calculating the target engine torque Te ゜. This arithmetic unit will be described later in detail. A block 108 indicates an arithmetic unit for calculating the target throttle opening θth ゜ from the target engine torque Te ゜ and the actual engine rotation speed Ne by using an equation or a map. Block 110 indicates a control system for feedback-controlling the control voltage Vth of the throttle actuator 19 so that the actual throttle opening θth becomes the target throttle opening θth ゜. For example, equation (3) may be used for this control. Vth = k ₃ × (θth ゜ −θth) (3) In the block 100, the target output horsepower PS ゜ is determined by other factors, such as a running road gradient, a vehicle weight, an external switch (economy pattern or power pattern, etc.). May be corrected or changed as a parameter. Further, in the block 102, the target input-side rotation speed Nin よ い may be corrected or changed by using other factors such as a vehicle speed, an engine cooling water temperature, a running road gradient, a vehicle weight, an external switch, and an air-fuel ratio as parameters. . Further, at block 108, the target throttle opening θt
h ゜ depends on other factors, such as engine coolant temperature, air-fuel ratio,
Alternatively, the amount of temporal change in the input-side rotation speed of the CVT may be corrected or changed as a parameter. Next, the details of each device in the block 106 will be described. Block 106-1: The basic target engine torque Te ゜ 1 is obtained as a function of the engine speed Ne by the following equation. Te ゜ 1 = g ₁ (Ne) (4) Equation (4) is determined on the optimal fuel consumption line A as shown in FIG. 5, for example. Block 106-3: Change Δ in output torque due to inertia moment I on the input side of engine, clutch, and continuously variable transmission
Tei is obtained by the following equation. ΔTei = I · dNe / dt (5) Since Ne = Nin (the input-side rotation speed of the continuously variable transmission) except for the half-clutch state, Nin may be used instead of Ne. In the case of a half-clutch, ΔTei = I ₁ · dNe / dt + I ₂ dNin / dt (6) Where I ₁ is the moment of inertia on the engine side,
I ₂ is the input side the moment of inertia of the continuously variable transmission. In addition,
In speed ratio control of a continuously variable transmission, for example, Japanese Patent Application No. 60-11
In a method of controlling the shift speed to become the target value dNin ゜, such as 5055, ΔTei may be obtained as ΔTei = I · dNin ゜ (7). When the equation (7) is used, it is not necessary to calculate the differential value of the rotation speed. Block 106-5: An estimated value Te of the engine torque is calculated from the throttle opening θth and the engine speed Ne by the following equation. Te = g ₂ (Ne, θth) (8) Block 106-7: Engine torque required from target output horsepower PS ゜ (necessary engine torque) Te ^* (equivalent to “target output value” in claims) ) Is calculated by the following equation. Te ^* = PS ゜ / Ne (9) Block 106-9: The difference ΔTe between the required engine torque Te ^* and the actual torque is obtained by the following equation. ΔTe = Te ^* − (Te−ΔTei) (10) This (Te−ΔTei) corresponds to the “corresponding actual output value” in the claims. This actual output value (Te−ΔTei) is
The engine is in charge of the value of the potential torque Te minus the inertia torque ΔTei. That is, even when the value of the inertia torque ΔTei necessary for increasing the engine rotation speed is large, such as when shifting during acceleration, the actual output value that is actually occurring is accurately indicated. Block 106-11: The correction value ΔTe ゜ 2 of the basic target engine torque Te ゜ 1 is obtained by the following equation in relation to the torque difference ΔTe obtained in block 106-9. Incidentally, it shows a characteristic example of the g ₃ in the block 106-11 in FIG. ΔTe ゜ 2 = g ₃ (ΔTe) (11) Plot 106-13: A target engine torque (final target value of engine torque) Te ゜ is obtained by the following equation. The characteristics of the function g ₃ of Te ° = Te ° 1 + .DELTA.Te ° 2 ... (12) block 106-11, the torque difference ΔT
When e is small, the correction value ΔTe ゜ 2 is made small or zero, and when ΔTe is large, ΔTe ゜ 2 is made large, so that when the difference between the target output and the actual output is small, the correction value ΔTeΔ2 is reversed. When the difference between the target output and the actual output is large, it is possible to remove the vehicle from the optimal fuel consumption line and secure the traveling performance, thereby achieving both the fuel consumption and the traveling performance. FIG. 4 shows a flowchart corresponding to FIG.
As is clear from the figure, Te ゜ 1, ΔTei, Te, Te ^* ,
The operations are performed in the order of ΔTe, ΔTe {2, Te}. Since the contents of the arithmetic expression in each step have already been described in detail, a duplicate description will be omitted. In the above embodiment, the correction value ΔTe ゜ 2 of the basic target engine torque Te ゜ 1 is the required engine torque Te ^*.
Although only the difference ΔTe between the actual output value Te and the actual output value Te−ΔTei is used as the function, this ΔTe may be combined with another signal corresponding to the use area. For example, ΔTe ゜ 2 = g ₃₁ (ΔTe, PS) PS = Ne × Te (13-1) ΔTe ゜ 2 = g ₃₂ (ΔTe, Te) (13-2) ΔTe ゜ 2 = g ₃₃ (ΔTe, Ne) (13-3) ΔTe ゜ 2 = g ₃₄ (ΔTe, Ne, Te) (13-4) The meaning of these equations is to change the correction torque ΔTe ゜ 2 with respect to the torque difference ΔTe with PS, Te, Ne, etc. representing the engine operating range at that time. This makes it possible to change the correction value of the target engine torque according to the engine usage range. Further, block 106-11 replaces torque difference ΔTe with
Another signal representing the difference from the target output value may be used. That is, ΔPS = PS ゜ −PS (14) In the above embodiment, the CVT is set with the output horsepower as the target. However, the present invention is applied to a method of controlling the vehicle drive torque T _D゜ as the target value (for example, Japanese Patent Application No. 60-248397). You can also. FIG. 7 and FIG. 8 are block diagrams thereof. FIGS. 7 and 8 correspond to FIGS. 3 and 1, respectively, of the previous embodiment. Since the basic principle itself of the portion according to the present invention is common, it is only shown in the drawings, and detailed description is omitted. In carrying out the present invention, it is needless to say that various corrections in consideration of other signals or elements are effective in terms of controllability and accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a part of the configuration of an embodiment of a vehicle drive system control apparatus according to the present invention, and FIG. 2 is an automobile engine to which the above embodiment is applied. FIG. 3 is an overall block diagram showing the configuration of an embodiment of a vehicle drive system control apparatus according to the present invention, and FIG. 4 is a control routine in the above embodiment apparatus. FIG. 5 is a flowchart showing a relationship between an engine rotation speed and an output torque for showing an optimal fuel economy line, and FIG.
FIGS. 7A and 7B are diagrams showing the relationship between the engine rotation speed and the output torque for explaining the technology disclosed in Japanese Patent Application Laid-Open No. 58-39870. FIGS. 7 and 8 show a second embodiment of the present invention. FIG. 3 is a block diagram corresponding to FIG. 3 and FIG. 1, respectively. E / G: Engine, θac: Accelerator opening, Nin: Input side rotation speed, Nin ゜: Target input side rotation speed, PS ゜: Target output horsepower, Te ゜ 1: On the optimal fuel efficiency line Basic target engine torque that can be run (basic target value), ΔTe ゜ 2: Correction value, Te ^*: Required engine torque (target output value), Te: Estimated value of engine torque ΔTei: Moment of inertia Te目標: target engine torque (target value), θth: throttle opening, θth ゜: target throttle opening.

Claims (1)

(57) [Claims] In a control device for a vehicle drive system including an engine having a means capable of changing an engine torque independently of an accelerator opening and a continuously variable transmission capable of controlling a speed ratio in a stepless manner, a target output horsepower is controlled by the accelerator opening. Means for determining the actual rotation speed of the engine, means for determining the actual rotation speed of the engine, and the actual engine rotation determined using the engine torque for operating the engine near the optimal fuel economy line as the basic target engine torque. Means for determining based on speed; and a difference between the target output value and an actual output value corresponding to the target output value, wherein the target output horsepower or a required engine torque for achieving the target output horsepower is set as a target output value. And a means for determining a correction value of the basic target engine torque based on a difference between the target output value and the actual output value; Means for calculating a sum of the target value and the correction value, and means for performing feedback control on the means for changing the engine torque using the obtained sum as a final target engine torque so that the target engine torque and the engine torque coincide with each other. A control device for a vehicle drive system, comprising: 2. In a control system for a vehicle drive system including an engine having means capable of changing an engine torque independently of an accelerator opening and a continuously variable transmission capable of controlling a speed ratio in a stepless manner, a target drive torque is controlled by the accelerator opening. Means for determining the actual rotation speed of the engine, means for determining the actual rotation speed of the engine, and the actual engine rotation determined using the engine torque for operating the engine near the optimal fuel economy line as the basic target engine torque. Means for determining based on speed, and a difference between the target output value and an actual output value corresponding to the target output value, wherein the target output horsepower or a required engine torque for achieving the target drive torque is set as a target output value. Means for detecting a correction value of the basic target engine torque based on a difference between the target output value and the actual output value; and Means for calculating the sum of the reference value engine torque and the correction value; and means for changing the obtained engine torque as the final target engine torque so that the target engine torque and the engine torque match. A control device for a vehicle drive system, comprising: means for performing feedback control.