JPS62199540A - Control method for vehicle drive system - Google Patents

Abstract

PURPOSE:To obtain an appropriate engine brake condition, by setting the desired horse power to a negative value in accordance with the opening degree of an accelerator and the amount of depression of a brake pedal if the opening degree of the accelerator is below a predeter mined value when the desired output horse power is computed in accordance with the opening degree of the accelerator sensor and the speed of the vehicle. CONSTITUTION:During running of a vehicle, at first a computer 100 computes a desired horse power PS deg. in accordance with an accelerator opening degree thetaac, a brake depression amount and a vehicle speed V. In this case, when the accelerator opening degree is below a predeter mined value which is other than a value corresponding to the full close position of the accelera tor, the desired horse power PS deg. is set to a negative value is accordance with the accelerator opening degree, the brake depression amount and the vehicle speed. Then, a computing unit 102 computes a desired input side rotational speed Nin deg. for a continuously variable transmission in accordance with the desired horse power PS deg., and a control system 104 controls a flow control valve in a hydraulic circuit for the continuously variable transmission in accordance with the thus computed value. Further, a desired opening degree for a throttle valve is obtained in accordance with an desired engine torque Te deg. and an actual torque Te which are computed by a computing unit 106 in accordance with the above-mentioned data PS deg. and an actual input side rotational speed Nin.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling a vehicle drive system, and in particular, the present invention includes an engine having means for changing the engine torque by 1q independently of the accelerator opening, and a continuously variable transmission capable of steplessly adjusting the speed ratio. This invention relates to improvements in control methods for vehicle drive systems.

[Prior Art 1] As one type of automatic transmission mechanism for vehicles, there is a continuously variable transmission mechanism driven by a belt or the like. This continuously variable transmission mechanism generally has a V-shaped boob device on the input shaft and output shaft, respectively, which consists of a fixed boob and a movable boob and whose effective diameter is variable by a hydraulic servo device. Between the devices!
) The rotation of the input shaft can be transmitted to the output shaft in a stepless manner by means of the twisted transmission belt. Normally, the oil flow to the hydraulic servo device on the input side is changed by a side control valve to forcibly change the effective diameter of the input side type boob device, while the oil flow to the hydraulic servo device on the output side is The oil pressure is changed by a pressure control valve, and the structure is such that torque can be transmitted without the transmission belt slipping in accordance with the change in the effective diameter of the input-side {circle around (2)} type boob device. When introducing such a continuously variable transmission mechanism into a vehicle's drive system, a means is generally provided to control the engine torque to a target value independently of the accelerator pedal, and the target output is adjusted depending on the accelerator opening, etc. The horsepower or target vehicle drive torque is determined, and the engine torque and the speed ratio (output side rotation speed/input side rotation speed) of the continuously variable transmission mechanism are controlled in accordance with the target output horsepower or target vehicle drive torque. ing. In this case, in order to control the lateral speed ratio of the continuously variable transmission i, only the input side rotational speed may be controlled, and as a result, the speed ratio may be controlled. By the way, one of the major purposes of introducing such a continuously variable transmission mechanism in the drive system of the 11 cars is to ensure that the vehicle always runs on the optimum fuel efficiency line (line A in Figure 8) within the engine usage range. , it's a joke to improve fuel efficiency. Therefore,
In general, the speed ratio is controlled to become larger when the throttle opening is small, so for example, engine braking is applied to a platform traveling downhill with the throttle opening at or close to zero. The problem was that it wasn't very effective. To address these issues,
Conventionally, for example, Japanese Patent Application Laid-open No. 58-191359 and Japanese Patent Application Laid-Open No. 58-1919
No. 1360, No. 58-193960, etc., disclose techniques for applying engine braking. [Problems to be Solved by the Invention] However, the above-mentioned disclosed technologies all focus on control when the accelerator is fully closed, and there is a problem in that they may not always be able to respond flexibly to the driver's wishes. there were. That is, the conventional technology disclosed regarding engine braking has a problem in that the driver cannot freely adjust whether he wants the engine brake to be applied fully or lightly. According to the conventional disclosed technology, when the accelerator is depressed even slightly, the speed ratio is controlled based on the optimum fuel efficiency line, so engine braking is hardly applied, and therefore engine braking is applied every time the accelerator is slightly depressed or released. There was a problem where it would turn on and off. In order to eliminate these problems, the applicant disclosed a technology in a patent application dated the same date that allows the driver to adjust the effect of engine braking according to his or her intention via the accelerator pedal. However, information on only the accelerator opening is not necessarily sufficient to more accurately grasp the driver's intention.

[Purpose of the invention]

The present invention was made in view of these problems, and it is possible to accurately grasp the driver's intention, and then adjust the way the engine brake is applied according to the driver's intention. An object of the present invention is to provide a control device for a vehicle drive system that allows the vehicle to travel more in accordance with the driver's intention when traveling downhill or the like.

[Means to solve the problem]

The first invention is a method for controlling a vehicle drive system, which is equipped with an engine having means for changing the engine torque independently of the accelerator opening, and a continuously variable transmission capable of changing the speed ratio steplessly. When the accelerator opening is less than a predetermined value set other than the fully closed equivalent value, the target output horsepower or target vehicle drive torque determined depending on the accelerator opening, etc. is set to a negative value, and The above object is achieved by setting the negative value continuously or stepwise depending on at least the accelerator opening degree and the brake depression amount. Further, the second invention provides a method for controlling a vehicle drive system that includes an engine that has means for changing engine torque independently of the accelerator opening and a continuously variable transmission that can control the speed 1a ratio steplessly. In the above, when the accelerator opening is less than a predetermined value set other than the value equivalent to fully closed, the speed ratio is set smaller than the speed 1a ratio determined from the optimum fuel economy line, and the value is set at least as low as the accelerator opening. The above objective can also be achieved by setting the pressure continuously or stepwise depending on the degree of braking and the amount of depression of the brake. In addition, in the above configuration, "an engine having a means for changing the engine torque independently of the accelerator pedal" means:
[Engine torque is not determined to some degree by the accelerator opening, and even with the same accelerator opening, different engine torques can be generated by changing the intake air depending on various driving conditions, etc.] means "engine". Therefore, some of these types of engines include so-called linkless engines in which the accelerator pedal and the means to actually change the engine torque, such as the throttle valve, are completely independent, as well as engines in which the accelerator pedal and the throttle valve are linked, for example. Even if it is classified as a type, it also includes a type of engine in which the engine torque can be changed even with the same accelerator opening degree by opening or closing a bypass valve or the like depending on driving conditions. In this case, the "throttle valve and bypass valve" become "means that can change the engine torque." [Function] According to the third aspect of the present invention, the accelerator opening degree is first selected as information for detecting the driver's intention to apply the engine brake, and when the accelerator opening degree is below a predetermined value set other than the fully closed value, Then, the target output horsepower or the target vehicle drive torque is set to a negative value (first invention), or the speed ratio is set smaller than the Q optimum fuel consumption line (second invention), and this negative value or speed Since the ratio is set continuously or stepwise depending on at least the accelerator opening degree and the amount of brake depression, strong engine braking is applied when the accelerator is fully closed, and strong engine braking is applied when the accelerator is slightly depressed. In addition to being able to apply a weaker engine brake to the vehicle, it is also possible to change the way the engine brake is applied depending on the amount of brake pedal depression, which allows the engine brake to be applied in accordance with the driver's intentions. You will be able to run. That is, in the past, the contact point for determining whether or not the driver intended to apply engine braking was set at the time when the accelerator was fully depressed, but in the present invention, this contact point is set at a position where the accelerator is depressed slightly, and when The effectiveness of the engine brake is adjusted by 1q depending on the accelerator opening at the time. As a result, the engine brake can be applied according to the opening degree of the accelerator pedal even if the accelerator pedal is not fully closed, and problems such as when the engine brake is suddenly applied only when the accelerator pedal is fully closed can be avoided. It can be resolved. Furthermore, since the way the engine brake is applied can be changed depending on the amount of brake depression, engine braking can be performed according to the driver's intention even when the accelerator pedal is not pressed. In addition, conventionally, fuel cut is performed when the accelerator is fully closed (when the engine rotates at a predetermined speed or higher), but in the present invention, even when the accelerator is not fully closed, the negative target output horsepower or negative target Once the vehicle drive torque is set, fuel can be cut off, thereby improving fuel efficiency. In a preferred embodiment, the negative value or speed ratio is set depending on the accelerator opening, brake depression, and vehicle speed. Also, preferably, when the brake depression ω is zero, the accelerator opening is determined, and when the accelerator opening is zero, the brake depression amount is
When both the brake depression amount and the accelerator opening degree are not zero, the accelerator opening degree is given priority and the speed ratio is set to the negative value or the predetermined value or less, and when both the brake depression amount and the accelerator opening degree are zero, This is to set the negative values or speed ratios to match. During normal driving, when the accelerator pedal is depressed, the amount of brake depression is zero. Further, when the brake is depressed, the accelerator opening is zero. Therefore,
When either of them is depressed, the target output LG force or target vehicle drive torque may be set according to the opening degree or amount of depression of the depressed side. In this case, the brake should be depressed first (if both 1 and the accelerator opening are not zero, the accelerator opening should be 0). Furthermore, if the speed ratio is made to match the negative value or a predetermined value or less when both the amount of brake depression and the degree of accelerator opening are zero, each state of accelerator on-accelerator off and brake off-brake on can be changed. This allows for smooth continuity. [Examples] Examples of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows the control of the vehicle drive system according to the present invention. The overall outline of an automobile engine and a continuously variable transmission to which an embodiment of the device is applied is not shown. 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. This CVT includes V-shaped pulley devices 10 and 14 on the input shaft 6 and on the output shaft 8, respectively, each consisting of a fixed pulley 11.15 and a movable pulley 12.16. The input-side fixed pulley 11 is fixed to the input shaft 6, and the input-side movable pulley 12 is fitted to the outer periphery of the input shaft 6 with a spline, a ball bearing, etc. so that it can move ωJ in the axial direction. Similarly, the output side fixed boob 915 is fixed to the output shaft width, and the output side movable pulley 16 is fitted to the outer periphery of the output shaft 8 with a spline, a ball bearing, etc. so as to be movable in the axial direction. The pressure-receiving area of each movable pulley 12.16 is set such that input side>output side, and the effective diameter can be forcibly changed to change the speed ratio on the input side. Further, the axial arrangement of the fixed pulley 11.15 and the movable pulley 12.16 on the input side and the output side is reversed to each other, so that the transmission belt 18 is always engaged and hung at right angles to the output shaft 6.8. It's Nishide. The opposing surfaces of the fixed pulley 11.15 and the movable pulley 12.16 are formed on tapered surfaces that increase their distance from each other radially outwards. In addition, a transmission belt 18 having an isosceles trapezoidal cross section is connected to the ■-shaped boolean devices 10 and 1 on the input side and the output side.
It can be hung between 4. The contact position of the transmission belt 18 in the radial direction on the boot surface changes continuously as the clamping force of the fixed and movable boots of each square-shaped boot device 10.14 changes. Input side■
When the contact position of the transmission belt 18 on the mold boom table 10 moves radially outward, the contact position of the transmission belt 1-18 on the output side V-gift device moves radially inward, CVT speed ratio C (-rotational speed N0U of output shaft 8
t/rotational speed N in of the input shaft 6) increases, and in the opposite case the speed ratio e decreases. The power of the output shaft 8 is transmitted to the driving wheels via a forward/reverse 17) changeover 'T1 star gear system, a gear gear system for deceleration, a differential gear system, etc. (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. Also, the opening degree of the engine E/G intake throttle is
It is controlled by a throttle actuator 19 independent of the accelerator pedal 36. The brake sensor 22 is located at y21 of the brake pedal 22A.
Detect Komidai. The input and output rotation angle sensors 20.21 detect the rotation angle of the pulley 11.16, respectively, and as a result the rotation speed (
Vehicle speed V) is detected and converted from the rotational speed on the output side. The pressure control valve 24 is connected to the reservoir 2 by the oil pump 25.
The line pressure PL8 of the oil passage 29 is regulated by controlling the release of oil as a hydraulic medium sent from 6 through the oil passage 27 to the oil passage 28. 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 inflow and outflow of oil to the input movable pulley 12. In order to maintain the speed ratio e of the CVT constant, the oil passage 33 is disconnected from the line pressure oil passage 31 and the drain oil passage 32 that branch from the oil passage 29. As a result, the axial position of the input end open pulley 12 is maintained constant, and the speed ratio e is also maintained 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 clamping force between the input pulleys 11 and 12 is increased, and the input pulley 1
The contact position of the transmission belt 18 on the 1.12 plane moves radially outward, increasing the speed ratio e. Conversely, in order to reduce the speed ratio e, the oil in the hydraulic servo device of the input movable pulley 12 is drained to the atmosphere through the drain oil passage 32, and the tightness between the input pulleys 11 and 12 is reduced. Try to reduce the applied force. Although the oil pressure in the oil passage 313 is below the line pressure PL,
+irj As mentioned above, since the piston pressure receiving area of the hydraulic servo device of the input side movable pulley 12 is set larger than the piston pressure receiving area of the hydraulic servo device of the output side movable pulley 16, the tightening of the input side pulley 11. It is possible to make the biasing force greater than the clamping force of the output pulley 15,16. By changing the tightening force of the input pulley 11.12 with the flow control valve 30, the effective diameter between the input pulleys 11.12 is changed, while the output pulley 15.16
The transmission belt 18 follows the change in the effective diameter on the input side.
The line pressure PL is regulated by the pressure control valve 24 so that a tightening force is generated that ensures torque transmission without slipping. The electronic control unit 38 includes a D/A converter 401 interface 4, an A/D converter 42, and a CPU 4, which are connected to each other by an address data bus 39.
3. Includes RAM44 and ROM45. The analog output θaC1 of the accelerator pedal sensor 34 and the analog output θbr of the brake sensor 22 are output from the A/D converter 4.
The pulses of the rotation angle sensors 20 and 21 are sent to the input interface 41. Control tll'F pressures Vth, Vin, and Vout to the throttle actuator 19, flow control valve 30, and pressure control valve 24 are sent from the D/A converter 40 via amplifiers 49, 50, and 51, respectively. FIG. 3 (A> shows the relationship between the input voltage and output current of the amplifier 49 for the throttle actuator 19, and FIG.
B) shows the relationship between the input current of the throttle actuator 19 and the intake throttle opening. Therefore amplifier 4
The throttle opening increases in proportion to the input voltage of 9. 4(A) shows the relationship between the input voltage and output current of the amplifier 50 for the flow control valve 30, and FIG. 4(B) shows the relationship between the input current of the flow control valve 30 and the input side hydraulic servo of the movable pulley 12. It shows the relationship with the outlet. Therefore, the speed ratio C is proportional to the change in the input current of the amplifier 50. FIG. 5A shows the relationship between the input voltage and output current of the amplifier 51 for the pressure control valve 24, and FIG. 5B shows the relationship between the input current of the pressure control valve 24 and the line pressure PL. ing. Therefore, the line pressure PL changes linearly with changes in the input voltage of the amplifier 51. Even if the input current to the pressure control valve 24 is zero, the line pressure PL is maintained at the predetermined level flu P L +. A predetermined oil pressure is supplied to the hydraulic servo to ensure minimum torque transmission in the CVT. A block diagram of the control system of this device is not shown in FIG. In the figure, a block 100 represents a target output horsepower P based on the accelerator opening θaC, the brake depression amount θbr, and the vehicle speed ■.
This figure shows an arithmetic unit that calculates S' using a formula or a map. An example of the map is shown in Figure 1.As is clear from the 1° diagram,
When the accelerator opening degree is smaller than a predetermined value θ1 to θ3 (depending on the vehicle speed), the target output horsepower PS is set to a negative value according to the accelerator opening degree and the vehicle speed.
The target output horsepower when C and maximum brake depression θbr are both zero is set to a value PS+° to PS3°, which is the same at each vehicle speed. Note that unless both the accelerator pedal stroke θaC and the brake pedal depression pitch θbr are not zero, the target output horsepower PS° is determined by the accelerator pedal stroke θaC. Block 102 represents a computing unit that calculates the target input side rotational speed 1'Jin' from the target output horsepower PS°. For example, when the target output horsepower PS is positive,
It is set based on the optimum fuel efficiency line A as shown in the figure. When driving performance is important, it may be set to a higher rotation side (line B). On the other hand, if the target output horsepower PS" is negative, set it based on the line when the throttle is closed, for example. In this case, the target output horsepower PS" and the target input side rotation speed N
The relationship with in' is as shown in FIG. As is clear from the figure, the setting is such that when the target output horsepower PS' is negative, the target input side rotational speed Nin' increases (the speed ratio e decreases). From Fig. 1, the target output horsepower PS' is set to become negative before the accelerator opening is fully closed, and the negative value is determined by the accelerator opening, brake depression amount, and engineering ↑f speed. As a result, the target input side rotational speed N in'' also starts to increase (the speed ratio e decreases) before the accelerator opening is fully closed, and the degree of increase depends on the accelerator opening and This depends on the brake depression amount l and the vehicle speed.Block 104 controls the flow fu1 so that the actual input side rotational speed Nin of the CVT becomes the target input side rotational speed Nin'.
1 Control voltage Vin of control valve 30 is controlled by feedback control 61
1-! This shows a control system that controls the speed ratio e of the CVT by controlling the speed ratio e of the CVT. For this control, an arithmetic expression such as equation (1) is used, for example. Vin=k + (N in' - N in) - (
1) When controlling J3, it is up to you to make corrections according to oil temperature, etc., and use a more accurate calculation formula. Block 106 calculates the target engine torque Te° based on the target output horsepower PS° and the actual input side rotational speed N1n of the CVT.
This figure shows an arithmetic unit that calculates by a formula or a map. For example, equation (2) is used for this derivation. Te"=to, 2 X PS"/N :n・(2
) Block 108 is the target engine torque Te. and the actual engine rotational speed N (4) indicate a table calculator that calculates the target throttle opening θ[1° by a formula or a map.Block 110 indicates that the actual throttle opening θth is This is a control system that performs feedback control of the control voltage vth of the thrower 1 to the actuator 1 so that the voltage Vth becomes θth''.For example, it is preferable to use equation (3) for this control.Vth=ks ...(3
) In the block 100, the target output horsepower may be modified or changed using other factors such as road slope, vehicle weight, external switch (economy pattern or power pattern selection switch), etc. as parameters. Further, in block 102, the target input side rotational speed Ni
n'' may be modified or changed using other factors such as vehicle speed, engine cooling water temperature, running road gradient, vehicle weight, external switch, air-fuel ratio, etc. as parameters.Furthermore, in block 108, target slots 1 to 1 are determined. The lulami θth' may be modified or changed using other factors, such as engine cooling water (crystal), air-fuel ratio, or the amount of change over time in the input side rotational speed of the CVT.Here, the input side of the CVT It is best to consider the amount of change in rotational speed over time when changing gears in a CvT: engine-clutch-
This is because the actual output torque changes due to the influence of the ttq moment on the CVT input side. To correct this, for example, the target engine torque Te' may be replaced by the following equation. Tc”=Te’+k4xd/dt(Ni
n) - (4) FIG. 7 shows a flowchart of the above control. First, in step 200, the accelerator opening θaC, the brake depression θbr, the vehicle speed ■, and the input side rotation speed 11Nin
1 Engine rotational speed Ne and throttle opening θth are read. Next, in step 202, the target output horsepower PS'' is obtained as a function f1 of the accelerator opening θaC, the brake pedal opening θb'', and the vehicle speed V. Thereafter, in step 204, the target input side rotation 1[fNin' is obtained in step 202. The target output horsepower PS' is determined as a function "2. In step 206, the target input side rotational speed Nin" determined in step 204 is used to calculate the flow Ei ul
The control voltage Vin of the 1211 valve 30 is expressed by the formula k, (Nin
”-Nin). Step 20
8, the target engine torque Te" is E? of the input side rotational speed Nin and the target output horsepower PS". It is determined as 1lf3. In addition, in step 210, the target throttle opening θth'' is determined based on the target engine 1˜lux Te'' obtained in step 208 and the engine rotational speed N.
It is obtained as a function r4 with e. And step 21
2, the control U++ of the throttle actuator 19
The voltage V[11 is found by the formula 3(θth'-θ(i)). According to the above embodiment, the accelerator opening degree θaC is the predetermined value θ1.
- θ3 (depending on vehicle speed) or less, the strength of the engine brake can be arbitrarily controlled by pressing the accelerator and the brake. Further, the throttle opening degree is properly controlled to a predetermined value regardless of whether it is in a steady state or in a transient state, and the output torque of the engine is controlled accordingly. In a J5, for example, a J3 in a diesel engine, the same effect as in the above embodiment can be obtained by replacing the target throttle opening with the target fuel injection ratio (■). Furthermore, in the above embodiment, the input side rotational speed of the CVT was compared with the target input side rotational speed for feedback control, but this is done by changing the CVT speed ratio e to the target speed ratio e.
Naturally, the same effect as the above embodiment can be obtained even if the feedback control is performed in comparison with the angle .degree. In this case, the target speed ratio e° is Nout /Nin” (No
ut can be determined as the output side rotational speed of the continuously variable transmission), and the control voltage Vin of the flow rate control valve 30 is 5
It can be obtained as (Q'-e). The second embodiment of the present invention is not shown in FIGS. 10 to 13. In the previous embodiment, an example was shown in which the target output horsepower PS' was determined as the target output, but in this embodiment, the target vehicle drive torque T is determined as the target output. I'm trying to find 0. FIG. 10 does not show a block diagram of the control system of the apparatus to which this second embodiment is applied. The basic logic is similar to the previous embodiment. To explain briefly, in the figure, block 300 determines target vehicle drive 1-lux T based on accelerator opening θaC, brake pedal depression loss θbr, and vehicle speed V. 6 is shown using a formula or map. An example of this is shown in FIG. As is clear from the figure, when the accelerator opening θaC is 04 to θG or less, the target vehicle drive torque To'' is set to a negative value according to each vehicle speed. The target vehicle drive torque when both the pedal depressions θbr are zero is set to 1 straight TD4° to Toe°, which are the same at each vehicle speed.In addition, when the accelerator pedal stroke θaC1 and the brake pedal stroke lθbr are both not zero, the accelerator opening Eye 8 by θaC
F, the vehicle drive torque To'' is determined. Block 302 represents a computing unit that calculates the target input side rotational speed Nin' from the target vehicle drive torque To''. In this case, a positive edge of the target vehicle drive torque To' is determined based on the optimum fuel efficiency line, etc., and a negative edge is determined based on the line when the throttle is fully closed. An example of the target input side rotational speed Nin' determined in this manner is not shown in FIG. As is clear from the figure, the target vehicle drive torque To
When ' starts to become Ω, that is, when the accelerator opening degree θaC is not yet fully closed, the input side rotational speed N in' increases (the speed ratio e decreases). As is clear from FIG. 11, the target vehicle drive torque To' is set depending on the accelerator opening, the amount of brake depression, and the vehicle speed, so the target human power [1111 rotation speed Nir+' also depends on these. This will continue to increase. Block 304 shows a control system that controls the speed ratio C of the CVT by feedback adjusting the control voltage V10 of the flow rate control valve 30 so that the actual input side rotational speed Nin of the CVT becomes the target input side rotational speed Nin'. ing. Block 306 includes the speed ratio e and the target vehicle drive torque To
`` indicates a computing unit that calculates the target engine torque Te'' using a formula or a map. For example, equation (2) is used for this calculation. Te °=k 2 xe
1 calculator is shown. Block 310 shows a control system that performs feedback control of the control voltage vth of one throttle actuator so that the actual throttle distance 6th becomes the target throttle opening θth. The vehicle drive torque To'', the target input side rotational speed Nin' in block 302, and the target throttle opening θth' in block 308 may be modified or changed using other factors as parameters, as in the first embodiment. good. FIG. 13 does not show a flowchart of the above control. First, in step 400, accelerator rotation θaC, brake depression mθbr, vehicle speed ■, input side rotation speed N111
, engine rotational speed Ne, speed ratio e, throttle opening θ
th is read. Next, in step 402, the target vehicle drive torque To' is set to θaC,
The brake depression amount and the vehicle speed V are determined as a function "5. Then, in step 404, the target input side rotational speed Nin" is determined as the function '1llf6 of the target vehicle drive torque To° and vehicle speed ■ determined in step 202. . In step 406, the control 211 lightning pressure Vin of the flow rate control valve 30 is calculated using the target input side rotational speed Ni0° obtained in step a3 in step 404, using the formula (Nino-
It is determined by the end of the performance of Nin). In step 408, the target engine torque Te'' is determined as a function [7] of the speed ratio e and the vehicle drive torque To'. 21 degrees θth” is the target engine torque TO” obtained in step 408 and the engine rotational speed 1.
It is determined as the function "8" of mNe.Then, in step 412, J-3 selects the throttle actuator 1.
The two control voltages [[) are determined by 2 and 3 (Otllo-θth). This second embodiment can also achieve the same effect as the previous embodiment. (Effect of the invention 1 As explained above, according to the present invention, even if the accelerator opening is not in the fully closed state, a weak engine brake or a strong engine brake can be applied as necessary. -When the brake is further depressed,
A stronger engine brake can be applied in accordance with the amount of depression, and an excellent effect can be obtained in that it is possible to travel more stably and smoothly than before on downhill slopes and the like.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the accelerator opening degree and the target output horsepower in the first embodiment of the vehicle drive system control method according to the present invention, and FIG. The skeleton diagram shown in Figure 3 <A) showing the overall outline of the automobile engine and automatic transmission is based on the above-mentioned implementation 1? A diagram showing the input/output characteristics of the throttle actuator amplifier used in I,
Figure 3 <B) is a diagram that similarly shows the relationship between throttle actuator input and throttle opening, and Figure 4 (A)
Figure 4 (B) shows the input/output characteristics of the amplifier for the flow control valve, and Figure 4 (B) shows the input and output characteristics of the amplifier for the flow control valve.
Figure 5 (A) is a diagram showing the relationship between the speed ratio of
B) is a V diagram showing the relationship between the input of the pressure control valve and the line pressure, FIG. 6 is a block diagram of the control system, FIG. 7 is a flow chart showing the control routine, and FIG. Similarly, FIG. 9 is a diagram showing the relationship between engine rotation speed 1 and output torque, and FIG. 9 is a diagram showing the relationship between target output horsepower and target input side rotation speed. 6 and 13 show a second embodiment of the present invention, respectively.
This is a diagram corresponding to FIG. 1, FIG. 9, and FIG. 7. E/G...engine, 6...input shaft, 8...output shaft, θaC...accelerator opening, θbr...brake depression, ■...vehicle speed, Nin...input side Rotation speed, 1"Jin'...Target input side rotation speed, PS"...
Target output horsepower, Teo...Target engine torque, θ(h...Throttle opening, θth'...Target throttle opening, e...Speed ratio, eo...Target speed ratio.

Claims (6)

[Claims] (1) In a method for controlling a vehicle drive system comprising an engine having a means for changing engine torque independently of the accelerator opening and a continuously variable transmission capable of steplessly controlling a speed ratio, the accelerator opening is as follows: is less than a predetermined value other than the fully closed equivalent value, the target output horsepower or target vehicle drive torque determined depending on the accelerator opening degree etc. is set to a negative value, and the negative value is at least A method for controlling a vehicle drive system, characterized in that setting is performed continuously or stepwise depending on an accelerator opening degree and a brake depression amount. (2) The method of controlling a vehicle drive system according to claim 1, wherein the negative value is set depending on the accelerator opening, the amount of brake depression, and the vehicle speed. (3) Prioritizes the accelerator opening when the amount of brake depression is zero, the amount of brake depression when the accelerator opening is zero, and the accelerator opening when both the amount of brake depression and the accelerator opening are not zero. According to claim 1 or 2, the negative value is set to match the negative value when both the brake depression amount and the accelerator opening amount are zero. The described method for controlling a vehicle drive system. (4) A method for controlling a vehicle drive system comprising an engine having a means for changing engine torque independently of the accelerator opening and a continuously variable transmission capable of steplessly controlling the speed ratio, wherein the accelerator opening is as follows: is less than a predetermined value other than the fully closed equivalent value, the speed ratio is set smaller than the speed ratio determined from the optimum fuel economy line, and the value is made dependent on at least the accelerator opening and the amount of brake depression. A method for controlling a vehicle drive system, characterized in that the control method is set continuously or stepwise. (5) The method for controlling a vehicle drive system according to claim 4, wherein the speed ratio below the predetermined value is set depending on the accelerator opening, the amount of brake depression, and the vehicle speed. (6) Prioritizes the accelerator opening when the amount of brake depression is zero, the amount of brake depression when the accelerator opening is zero, and the accelerator opening when both the amount of brake depression and the accelerator opening are not zero. The speed ratio is set to be equal to or less than the predetermined value, and the speed ratio is set to match the speed ratio when both the brake depression amount and the accelerator opening amount are zero. A method for controlling a vehicle drive system as described in .