JPS62199536A - Control method for vehicle drive system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

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

[Conventional technology]

As one of the automatic transmission g1 mechanisms 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 the output shaft, respectively, which consists of a fixed boob and a movable boob and whose effective diameter is variable by a hydraulic servo device. The rotation of the input shaft can be transmitted to the output shaft in a stepless manner by means of a transmission bell 1 which is stretched between the devices. Normally, the oil flow to the hydraulic servo device on the input side is changed by a control valve to control the input side V'l.
! The effective diameter of the boob device is forcibly changed, while the hydraulic pressure of the hydraulic servo device on the output side is changed by a pressure control valve,
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 V-shaped boob device. When using such a continuously variable transmission mechanism in 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 value is adjusted depending on the accelerator opening etc. While determining the output horsepower or target vehicle drive torque, the engine torque and the speed ratio of the continuously variable transmission mechanism (output side rotation speed/input side rotation speed) are controlled in accordance with the target output horsepower or target vehicle drive torque. I have to. In this case, in order to control the speed ratio of the continuously variable transmission mechanism, only the input side rotational speed may be controlled, and as a result, the speed ratio may be controlled. By the way, in the drive system of a vehicle, such a continuously variable transmission 8
One of the major purposes of introducing 14% is to always keep the vehicle at the optimum fuel efficiency line within the engine usage range (line A in Figure 8).
The aim is to improve the fuel efficiency of actual vehicles by running them on the ground. Therefore, the speed ratio is generally controlled so that the smaller the throttle angle is, the larger the speed ratio becomes.
For example, there has been a problem in that engine braking is not very effective when driving downhill with the throttle opening at or close to zero. In order to deal with these problems, conventional methods have been used, for example,
-191360 and 58-19396Ql disclose a technique 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 intentions. 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.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and allows the driver to adjust how the engine brake is applied according to his/her intention, thereby making it easier to drive downhill etc. An object of the present invention is to provide a control device for a vehicle drive system that can drive a vehicle according to the driver's intention. [Means for Solving the Problems] The first invention includes an engine having means for changing the engine torque independently of the accelerator opening, and a continuously variable transmission capable of steplessly adjusting the speed ratio. In a vehicle drive system control method, if the accelerator opening is less than a predetermined value set other than the value equivalent to fully closed, the target output horsepower or target vehicle drive torque determined depending on the accelerator opening etc. is set to a negative value. The above object is achieved by setting the negative value to a value and setting the negative value continuously or stepwise depending on at least the accelerator opening degree. The second invention also provides a method for controlling a vehicle drive system that includes an engine that has means for changing the engine torque independently of the accelerator opening and a continuously variable transmission that can adjust the speed ratio steplessly. , when the accelerator opening is less than a predetermined value set to a value other than the value equivalent to fully closed, the speed ratio is set smaller than the speed ratio determined from the optimum fuel efficiency line, and the value is set to at least the accelerator opening. The above object is likewise achieved by setting the layers successively or in stages, depending on the layer. In addition, in the above configuration, "an engine having a means for changing the engine torque by 1q independently of the accelerator pedal" means that the engine torque is not uniquely determined by the accelerator opening, and even with the same accelerator opening, there are various For example, by changing the amount of intake air depending on the driving conditions, etc.
An engine capable of generating different engine torques. 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 the bypass valve] become [the means that can change the engine torque]. [Effect 1] In the present invention, the accelerator opening degree is selected as information for detecting the driver's intention to apply the engine brake,
When the accelerator opening is below a predetermined value, the target output horsepower or target vehicle drive torque is set to a negative value (first invention), or the speed ratio is set smaller than the optimum fuel efficiency line (second invention), and this negative Since the value or speed ratio is set continuously or stepwise depending on at least the accelerator opening, strong engine braking is applied when the accelerator is fully closed, and strong engine braking is applied when the accelerator is fully closed. This makes it possible to apply weaker engine braking when the vehicle is running, making it possible to drive with engine braking in accordance with the driver's wishes. That is, in the past, the contact point to determine whether the driver intended to apply engine braking was made when the accelerator was fully closed, but in the present invention, this contact point is set at a position where the accelerator is slightly depressed, and the The effectiveness of the engine brake can be adjusted according to the accelerator opening. As a result, engine braking can be applied in accordance with the opening degree of the accelerator pedal even if the accelerator pedal is not fully closed, and problems such as engine braking suddenly being applied only when the accelerator pedal is fully closed can be avoided. It can be resolved. Also, conventionally, fuel is cut when the accelerator is fully closed (when the engine rotates at a predetermined speed or higher).
In the present invention, even when the accelerator is not fully closed, fuel can be cut when a negative target output horsepower or a negative target vehicle drive torque is set, thereby improving fuel efficiency. It also becomes. In a preferred embodiment, the negative value or speed ratio is set depending on the accelerator opening and vehicle speed. [Fruitable Example 1] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 does not show an overall outline of an automobile engine and a continuously variable transmission to which an embodiment of the vehicle drive system 1III system according to the present invention is applied. In the figure, the output shaft 2 of the engine E/G is connected to the clutch IN.
It is connected to a belt-driven continuously variable transmission (hereinafter referred to as CVT) via the transverse 4. This CVT is provided with V-shaped boolean devices ff1lo and 14, each consisting of a fixed pulley 11.15 and a movable pulley 12.16, on the input shaft 6 and the output shaft 8. The input-side fixed pulley 11 is fixed to the input shaft 6, and the input-side movable pulley 12 is fitted on the outer periphery of the input shaft 6 with a spline, a ball bearing, etc. so as to be movable in the axial direction. Similarly, the output side fixed pulley 15 is fixed to the output shaft 8, and the output side movable pulley 16 is fitted on 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 applied at right angles to the output l1416.8. It is. 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. Further, a transmission belt 18 having an isosceles trapezoidal cross section is used as a V-shaped boob device 10.1 on the input side and the output side.
It can be hung between 4. The radial contact position of the transmission belt 18 on the boot surface changes continuously as the clamping force of the fixed and movable boot of each V-shaped boot device 10.14 changes. Input side V
When the contact position of the transmission belt 18 on the type booby device 10 moves radially outward, the contact position of the transmission belt 18 on the output side V-type pulley device moves radially inward, and the speed ratio e (= Rotational speed Nou 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 supplied by an M original gear device for forward/reverse switching, a gear device for deceleration, and a differential gear device (not shown) for forward/reverse switching. It is transmitted to the driving wheel via the first class. 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 input and output rotation angle sensors 20.21 respectively detect the rotation angle of the boot 911.16, resulting in 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 PL 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. Output side movable pulley 1
Line pressure P is supplied to the hydraulic servo device 6 through an oil passage 29.
L is supplied. The flow rate control valve 30 controls the amount of oil flowing into and out of 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 movable pulley 12 is maintained constant, and the speed ratio e is also maintained constant. In addition, in order to increase the speed ratio e, it is necessary to connect the line pressure oil passage 31 to the oil passage 3.
3, oil is supplied into the hydraulic servo device of the input side movable pulley 12. As a result, the clamping force between the input pulleys 11 and 12 is increased, and the input pulley 11
．． The contact position of the transmission belt 18 on the 12th surface moves radially outward, J, and the speed ratio e increases. Conversely, in order to decrease the speed ratio e, the oil in the hydraulic servo device of the input side movable boob 912 is allowed to flow through the drain oil passage 32 to the atmosphere side, and is then pumped between the input side pulleys 11 and 12. to reduce the tightening force. Although the oil pressure in the oil passage 33 is lower 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 is reduced to the output pulley 15.
．． It is possible to increase the tightening force more than 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 device 3B includes a D/A converter 40, an input interface 41, an A/D converter 42, a CPU 43, and a CPU 43, which are connected to each other by an address data bus 39.
It includes RAM44 and ROM45. The analog output θaC of the accelerator pedal sensor 34 is output from the A/D converter 4.
2 and the pulses of the rotation angle sensor 20.21 are sent to the input interface 41. Control voltages Vth, Vin, and Vout to one throttle actuator, the flow rate control valve 30, and the pressure control valve 24 are sent from the D/A converter 40 through eleven width switches 49.5o 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 e is proportional to the change in the input current of the amplifier 50. Figure 5 (A> shows the relationship between the input voltage and output current of the amplifier 51 for the pressure control valve 24, and Figure 5 (B) shows the relationship between the input current of the pressure control valve 24 and the line pressure PL. Therefore, the line pressure PL changes linearly in response to a change in the input voltage of the amplifier 51.Even if the input current of the pressure control valve 24 is zero, the line pressure PL is maintained at the predetermined value PL1. Even in the unlikely event that a break or a malfunction occurs in the electronic control device 38, a predetermined hydraulic pressure is supplied to the hydraulic servo of the movable pulley 12, 16, ensuring the minimum torque transmission in the CVT. A block diagram of the control system is not shown. In the figure, a block 100 indicates a computing unit that calculates the target output horsepower PS by an equation or a map based on the accelerator opening θaC and the vehicle speed V. An example of the map is shown in FIG. As is clear from the figure, the accelerator opening is at a predetermined value θ1~
When the torque is smaller than θ3, the target output horsepower PS'' is a negative value depending on the accelerator opening degree and the vehicle speed. Block 102 uses a resonator to determine the target input side rotational speed Nin'' from the target output horsepower PS'. It shows. To calculate this, when the target output horsepower PS is positive, set it based on the optimum fuel efficiency line A shown in Fig. 8, for example.When driving performance is important, set it on the higher rotation side (line B). On the other hand, when "target output horsepower PS" is negative,
For example, it is set based on the line when the throttle is fully closed. In this case, the target output horsepower PS° and the target input side rotation speed Ni
The relationship with n'' is as shown in Figure 9.As is clear from the figure, when the target output horsepower PS' is negative, the target input side rotational speed Nin' increases (speed ratio e decreases). As shown in Figure 1, the target output horsepower PS° is set to become negative before the accelerator opening is fully closed, so the target input side rotational speed Nin'' is also set when the accelerator opening is not fully closed. The speed ratio e starts to increase (the speed ratio e decreases) before it is closed. Block 104 is an i-instruction block that controls the speed ratio e of the CVT by feedback-controlling the control 211 voltage V1n of the flow control valve 30 so that the actual input-side rotational speed Nin of the CVT becomes the target input-side rotational speed Nin'. It shows the thread. For this control, an arithmetic expression such as equation (1) is used, for example. Vin=k+(Nin'-Nin)-(1)
It should be noted that in this control, for example, it is possible to make corrections according to the oil temperature, etc., and use a more accurate calculation formula. Block 106 calculates the target engine torque Te'' from the target output horsepower PS'' and the actual input side rotational speed Nin 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 calculation. Te”=k2XPS'/Nin-(
2) Block 108 determines the target throttle opening θ based on the target engine torque Te” and the actual engine rotational speed Ne.
It shows an arithmetic unit that calculates th' using a formula or a map. Block 110 is a control system that performs feedback control of the control voltage vth of the throttle actuator 19 so that the actual throttle angle θth becomes the target throttle opening θth.For example, using equation (3) for this control, Good. V th=k a X (θth'-〇th)...(
3) In the block 100, the target output horsepower is determined by other factors such as the slope of the running road, the weight, and the external switch (
It is also possible to modify or change the economy pattern, power pattern, etc. selection switch) as a parameter. Further, in block 102, the target input side rotational speed Ni
n' may be modified or changed by -5 using other factors such as vehicle speed, engine cooling water temperature, road slope, vehicle weight, external switch, air-fuel ratio, etc. as parameters. Furthermore, in block 108, the target throttle opening θ
th° may be modified or changed using other factors such as the engine cooling water temperature, air-fuel ratio, or the amount of change over time in the input side rotational speed of the CVT as a parameter. Here, it is good to consider the amount of change over time in the input side rotational speed of the CVT.
This is because the actual output torque changes due to the influence of the moment of inertia on the T input side. To correct this, for example, the target engine torque Te° may be replaced by the following equation. Te”=Te’+k4Xd/dt(Ni
n) ++ (4) FIG. 7 shows a flowchart of the above control. First, in step 200, the accelerator opening degree θQC, the vehicle speed ■, the input side rotation speed Nin, the engine rotation speed Ne,
The throttle opening degree θth is read. Next, in step 202, the target output horsepower PS° is determined as a function r1 of the accelerator distance θaC1 and the vehicle speed V. after that,
In step 204, the target input side rotational speed Nin° is determined as the target output horsepower PS' obtained in step 202.
is obtained as a function f2. In step 206, the control voltage v1r of the flow rate control valve 30 is determined using the target input side rotational speed Nin° obtained in step 204.
1 is obtained by calculating the equation k + (Nin''-44 inches). In step 208, the target engine torque Te° is obtained as a function [3] of the input side rotational speed Nin and the target output horsepower PS''. Also, step 21
0, the target throttle opening θth" is determined as a function r4 of the target engine torque Te° determined in step 208 and the engine rotational speed N8. Then, in step 212, the control voltage vsh of one throttle actuator is In the formula, 3(θth”−θth
) is determined by 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. 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. For example, in diesel engines, 6Fi
By replacing the target throttle distance with the target fuel injection port, the same effect as in the above embodiment can be obtained as is. In addition, in the above embodiment, the input side rotational speed of the CVT is compared with the target input side rotational speed to perform feedback control, but this is performed by comparing the speed ratio e of the CVT with the target speed ratio e° and performing feedback control. Even if it is controlled, it is naturally possible to obtain the same effect as in the above embodiment. In this case, the target speed ratio e° is Nout/Nin'
(Nout is the output side rotation speed of the continuously variable transmission), and the control voltage Vin of the flow control valve 30 is 5
It can be obtained as (e'-Q). A second embodiment of the present invention is 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 am trying to find °. FIG. 10 shows a block diagram of a control system of an apparatus to which this second embodiment is applied. The basic logic is similar to the previous embodiment. To explain briefly, in the figure, a block 300 calculates the target vehicle drive torque T based on the accelerator opening θaC and the vehicle speed V.
11 shows an example of this. As is clear from the figure, depending on each vehicle speed, when the accelerator opening θaC is 04 to θc or less, °, the target vehicle drive 1 torque To' is set to a negative value. Block 302 represents a computing unit that calculates the target input side rotational speed Nin'' from the target vehicle drive 1 torque To'. . In this case, the target vehicle drive torque To. A positive endpoint is determined based on the optimum fuel efficiency line, etc., and a negative endpoint is determined based on the line when the throttle is closed. The eye eλ input side rotation speed Nin obtained in this way
An example of " is shown in FIG. 12. As is clear from the figure, when the target vehicle drive torque To' starts to become negative, that is, when the accelerator opening θaC is not yet fully closed, the input side rotational speed Nin" increases (velocity ratio e decreases). Block 304 controls the flow rate control valve 3 so that the actual input side rotational speed Nin of the CVT becomes the target input side rotational speed Nin''.
A control system is shown in which the speed ratio e of the CVT is controlled by feedback-adjusting the control voltage vin of 0. Block 30G represents speed ratio e and 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
'' by a formula or map. Block 310 performs feedback control 2a of control voltage vth of throttle actuator 19 so that actual throttle opening degree 6th becomes target throttle opening degree θth'.
The control system is shown. Note that the target vehicle drive torque TD° in block 300, the target input side rotational speed 1'4'' in block 302, and the target throttle opening θth' in block 308 are determined by other variables as in the first embodiment. The factors may be modified or changed as parameters. Fig. 13 shows a flowchart of the above control. First, in step 400, accelerator opening θaC1 vehicle speed V, input side rotational speed Nin, engine rotational speed Ne,
The speed ratio e1 throttle distance θth is read. Next, in step 402, the target engine torque To
" is determined as a function f5 of the accelerator opening degree θaC and the vehicle speed V. Thereafter, in step 404, the target input side rotational speed Nin" is determined as a function f6 of the target vehicle drive torque To" determined in step 202 and the vehicle speed V. In step 406, step 4
The control voltage Vin of the flow control valve 30 is set to 1 (N
in' - N in). In step 408, the target engine torque Tc'
is determined as a function r7 of the speed ratio e and the target vehicle drive torque To''.In addition, in step 410, the target throttle opening θth' is determined by the target engine torque Te'' determined in step 408 and the engine rotational speed N.
It is obtained as a function f8 with e. and step 41
In 2, the control voltage vth of the throttle actuator 19 is obtained by the formula 3(θth''-θth). This second embodiment also provides the same effect as the previous embodiment. [Advantageous Effects of the Invention] 1. As explained above, according to the present invention, weak engine braking or strong engine braking can be applied as needed even if the accelerator opening is not in the closed state, resulting in more stable driving on downhill slopes, etc. In addition, the excellent effect of being able to run smoothly can be obtained.

[Brief explanation of drawings]

° Figure 1 shows the first method of controlling a vehicle drive system according to the present invention.
FIG. 2 is a diagram showing the relationship between the accelerator opening degree and the target output horsepower in the embodiment; FIG.
FIG. 3(A) is a diagram showing the input/output characteristics of the throttle actuator amplifier used in the above embodiment, and FIG. 3(B) is a diagram showing the relationship between the throttle actuator input and throttle opening. The diagram shown in FIG. 4 (A) also shows the input/output characteristics of the flow control well amplifier.
Fig. 4 (B) is a diagram showing the relationship between the input of the flow control valve and the speed ratio of the CVT, and Fig. 5 (A) is a diagram showing the input/output characteristics of the amplifier for the pressure regulating valve. , Figure 5(B)
is a 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, and FIG.
Similarly, FIG. 8 is a flowchart showing the control routine, and FIG. 9 is a diagram showing the relationship between engine speed and output torque.
Similarly, the diagrams do not show the relationship between the target output horsepower and the target input side rotation speed, and the diagrams, FIGS. 10, 11, 12, and 13 do not show the second embodiment of the present invention, but each 6, FIG. 1, FIG. 9, and FIG. 7. E/G...Engine, 6...Input shaft, 8...Output shaft, θaC...Accelerator opening, ■...Vehicle speed, N1'1...Input side rotation speed 1 stand, N10 °...Target input side rotation speed, PS'...Target output horsepower, Teo...Target engine torque, θlb...Storage angle, θ[11°...Target throttle opening, e...Speed ratio, eo...Target speed ratio.

Claims (4)

[Claims] (1) A method for controlling a vehicle drive system equipped with an engine having means for changing engine torque independently of the accelerator opening and a continuously variable transmission capable of steplessly adjusting the speed ratio, comprising: the accelerator opening; 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. (2) The method for controlling a vehicle drive system according to claim 1, wherein the negative value is set depending on an accelerator opening degree and a vehicle speed. (3) 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 adjusting the speed ratio, 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 consumption line, and the value is changed continuously or continuously at least depending on the accelerator opening. A method for controlling a vehicle drive system characterized by stepwise setting. (4) The method for controlling a vehicle drive system according to claim 3, wherein the speed ratio is set to be less than or equal to the predetermined value depending on the accelerator opening and the vehicle speed.