JPS6060363A - Speed ratio control device of continuously variable transmission for vehicle - Google Patents

Abstract

PURPOSE:To enhance drivability of a vehicle and its economic efficiency of fuel, by suppressing a change of speed of the engine when its actual speed is less than the discriminative control speed of speed change suppression with the vehicle under its decelerated condition. CONSTITUTION:A deceleration condition discriminating means, speed range discriminating means and a rotary speed change suppressing means are provided, and a change of speed of an engine is suppressed when its actual speed is less than the discriminative control speed of rotary speed change suppression with a vehicle under its decelerated condition. In this way, a good characteristic of reacceleration (drivability) and high economic efficiency of fuel are obtained by limiting a decrease of transmission efficiency of a continuously variable transmission when the vehicle is in its reaccelerated condition following the time of deceleration because the speed of the engine is maintained at a relatively high value even under a decelerated condition of the vehicle.

Description

Detailed Description of the Invention Technical Field The present invention relates to a speed ratio control device for a continuously variable transmission for a vehicle, and more particularly to a technology that provides both suitable drivability and fuel economy in a state where the vehicle decelerates (re-accelerates). It is something.

Conventional technology In a continuously variable transmission for a vehicle that continuously changes the rotation of an engine and transmits it to the wheels, a rotation speed detection means for detecting the rotation speed of the engine and a required load amount required for the engine are detected. requested load amount detection means; target rotational speed determination means for sequentially determining a target rotational speed of the engine based on the requested load amount from a predetermined relationship; and a rotational speed of the engine that matches the target rotational speed. A speed ratio control device including speed ratio adjusting means for adjusting the speed ratio of the continuously variable transmission has been considered. If such a speed ratio control device is used, the engine rotation can be made to match the target rotation speed with the best fuel consumption rate, so that favorable fuel economy can be obtained over the entire engine rotation range, especially in steady running conditions. There is a drawback that sufficient drivability and fuel economy cannot be obtained in a re-acceleration state following vehicle deceleration. That is, even when the vehicle is decelerating when the amount of accelerator operation is almost zero, the engine rotation speed is controlled to match the target rotation speed determined to be an extremely low value corresponding to the accelerator operation, and When the vehicle is in a re-acceleration state in which the accelerator operation amount is again increased, the engine rotation speed is made to match the target rotation speed that is largely determined in accordance with the throttle operation amount. The rise range is large and the speed ratio change of the continuously variable transmission is required to be large, which reduces the transmission efficiency of the continuously variable transmission and consumes a lot of vehicle acceleration time, making it difficult to achieve sufficient re-acceleration (drivability).
and fuel economy cannot be achieved.

Purpose of the Invention The present invention has been made against the background of the above circumstances,
The object thereof is to provide a speed ratio control device for a continuously variable transmission for a vehicle that provides high drivability and fuel economy in a state of re-acceleration following vehicle deceleration.

Structure of the Invention In order to achieve the above object, the speed ratio control device of the present invention includes: (1) deceleration state determining means for determining the deceleration state of the vehicle; (2) the actual rotational speed of the engine is determined in advance. (3) the vehicle is in a deceleration state, and the actual rotation speed of the engine is the rotation speed; The present invention is characterized by comprising: a rotational speed change suppressing means for suppressing a change in the rotational speed of the engine when the rotational speed is lower than a change suppression control determination rotational speed.

Effects of the Invention With this arrangement, as shown in the claim correspondence diagram of FIG. 1, the deceleration state of the vehicle can be determined by the deceleration state determining means, and the actual rotational speed of the engine can be determined in advance by the rotation range determining means. When it is determined that the rotation speed has decreased to a lower rotation range than the rotation speed change suppression control discrimination determination rotation speed, the rotation speed change suppressing means suppresses the rotation speed change of the engine. In other words, when the vehicle is decelerating and the engine rotational speed is lower than the rotational speed change suppression control determination rotational speed, the engine rotational speed change is suppressed, so the amount of accelerator operation is almost zero, and the amount of accelerator operation is significantly reduced. Compared to the conventional case where the actual engine rotation speed is lowered to follow the target rotation speed determined to be a small value, changes in the engine rotation speed are suppressed, and even in such a deceleration state, the engine rotation remains constant. The speed is maintained at a relatively high value. Therefore, in the reacceleration state that follows such deceleration, the target rotational speed is determined to be a relatively large value according to the amount of accelerator operation, but the engine rotational speed is maintained at a relatively high value during deceleration. Therefore, even during re-acceleration, the range of increase in engine speed and the range of change in the speed ratio of the continuously variable transmission are relatively small, limiting the decrease in transmission efficiency of the continuously variable transmission, resulting in high re-acceleration performance. (drivability) and at the same time, high fuel economy. Furthermore, as a result of suppressing changes in engine rotational speed when the vehicle is decelerating, the engine rotational speed is maintained at a relatively high value, but in such a case, the amount of accelerator operation is essentially zero. Therefore, fuel economy will not be affected by this condition.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 2, a Held type continuously variable transmission 14 is connected to the engine 10 via a clutch 12, and the rotation of the engine 10 is shown after being continuously changed by the Held type continuously variable transmission 14. It is not intended to be transmitted to the wheels. The heald type continuously variable transmission I4 includes an input shaft 16 connected to a clutch 12, a variable pulley 18 with a variable effective diameter attached to the input shaft 16, an output shaft 20, and an effective pulley attached to the output shaft 20. A variable pulley 22 whose diameter is variable, a conduction heald 24 stretched between the variable pulleys 18 and 22, and hydraulic cylinders 26 and 28 which change the effective diameter by changing the groove width of the variable pulleys 18 and 22.
It is equipped with The variable pulleys 18 and 22 have fixed rotating bodies 30 and 32 fixed to the input shaft 16 and the output shaft 20, respectively, and fixed rotary bodies 30 and 32 fixed to the input shaft 16 and the output shaft 20, respectively, and fixed rotary bodies 30 and 32 fixed to the input shaft 16 and the output shaft 20, respectively. I1
It consists of movable rotary bodies 34 and 36, which are rotated by hydraulic cylinders 26 and 2.
The diameter (effective diameter) of the transmission heald 24 can be continuously changed by being driven in the axial direction by hydraulic pressure applied to the space within the transmission heald 8 . Line hydraulic pressure is constantly supplied to the hydraulic cylinder 2B via an oil path 46 (described later), and the amount of hydraulic oil (operating hydraulic pressure) in the hydraulic cylinder 26 is adjusted by a speed ratio control valve 38, so that the movable rotating body The balance of forces applied to 34 and 36 is changed to change the speed ratio of the continuously variable transmission 14. Note that the pressure receiving area of the movable rotary body 34 is set larger than that of the movable rotary body 36.

The line oil pressure is obtained by adjusting the hydraulic oil pressure-fed from the oil tank 40 by the pump 42 by the pressure regulating valve 44, and then passing it through the oil passage 46 to the speed ratio control valve 3.
8 and hydraulic cylinder 28. The pressure regulating valve 44 includes a linear solenoid driven by a pressure regulating signal SP, which will be described later, and a valve element driven by the linear solenoid, and regulates the amount of hydraulic oil pumped from the pump 42 released into the oil tank 40. The line oil pressure is adjusted by changing it according to the signal SP.

The speed ratio control valve 38 includes a linear solenoid driven by a speed ratio signal SS to be described later and a valve element driven by the linear solenoid, and connects an oil passage 48 communicating with the hydraulic cylinder 26 with the oil passage 46. By changing the flow area, the amount of hydraulic oil supplied (hydraulic pressure) to the hydraulic cylinder 26 is adjusted, while the oil passage 48 and oil tank 4
By communicating with the return oil passage 50 to 0 and changing its circulation area, the amount of hydraulic oil discharged in the hydraulic cylinder 26 (
(hydraulic). That is, when the communication between the oil passage 48 and the oil passages 46 and 50 is substantially cut off by the speed ratio control valve 38 and the amount of hydraulic oil in the hydraulic cylinder 26 is kept constant, the speed ratio is fixed. , when the oil passage 48 and the oil passage 46 are in communication with each other, the hydraulic cylinder 2
The amount of hydraulic oil (oil FE) in the variable pulley 6 is increased, the effective diameter of the variable pulley 1B is increased, and the effective diameter of the variable pulley 22 is decreased, and the speed ratio is increased.

On the contrary, the speed ratio is reduced by making the oil passage 48 and the oil passage 50 communicate with each other.

A throttle valve 54 connected to an accelerator pedal 52 is attached to the intake pipe of the engine 10, and the opening degree θ of the throttle valve 54 is corresponded to by a throttle sensor 56, which is attached to the throttle valve 54 and serves as a required load detection means. The throttle signal TH, which is the voltage
It is supplied to the I10 boat 59 via the D converter 58. Further, a rotation sensor 60 as a rotation speed detection means and a rotation sensor 62 as a vehicle speed detection means are attached to the human power shaft 16 and the output shaft 20, respectively. I/F circuit 64 sends a pulsed rotation signal SE corresponding to
Meanwhile, the rotation sensor 62 supplies a pulsed rotation signal SC corresponding to the vehicle speed to the T/F circuit 64. I/
The F circuit 64 converts the rotation signals SE and SC into a code signal representing the number of pulses per unit time, and supplies the code signal to the I10 boat 59. The I10 port 59 is connected to the CPU 66, RAM 68° ROM 70 via a data bus line, and the CPU 66 has 1. RAM according to the programmed
68, the signal supplied to the I10 boat 59 is processed, and the speed ratio signal SS, which commands the speed ratio and its change speed, is sent to the speed ratio via the D/A converter 72 and the drive circuit 74. While supplying the pressure regulating signal SP to the control valve 38, the pressure regulating signal SP which commands the pressure of the line hydraulic pressure is sent to the pressure regulating valve 4 via the D/A converter 72 and the drive circuit 74.
Supply to 4. The drive circuit 74 is a so-called power amplifier, which amplifies the power of the speed ratio signal SS and the pressure adjustment signal '1tSP outputted from the D/A converter 72 with a predetermined gain, and controls the speed ratio control valve 38 and pressure adjustment. valve 4
It supplies the 4th linear solenoid.

FIG. 3 is a control block diagram of this embodiment.

The target rotational speed determining means 76 determines the required load amount from the throttle valve 5 based on the pre-stored relationship shown in FIG.
4, the target rotational speed Ne' is determined based on the opening degree θ.

The target rotational speed Ne' is a predetermined value so that the required horsepower corresponding to the throttle valve opening θ can be obtained at a minimum fuel consumption rate of 1. In the deceleration state determination means 7B, the actual rotational speed Ne of the engine 10 detected by the rotational speed detection means 80 is set to be continuously variable to make the actual rotational speed Ne of the engine 10 smaller than the target rotational speed Ne'. The direction of change in the speed ratio of the engine 14, in other words, the deceleration line of the vehicle is determined. The rotation range determining means 82 determines that the actual rotation speed Ne of the engine 10 is in a rotation range smaller than a predetermined rotation speed change suppression control determination rotation speed Ne. In the rotational speed change suppressing means 84, the actual rotational speed N of the engine 10 is detected by the rotational range determining means 82.
In a state where it is determined that e is larger than the rotation speed change suppression control determination rotation speed Ne, the target rotation speed Ne' in the speed ratio control control means 86 is set to the actual engine 1
By setting the value Ne-α close to 00 rotation speed Ne, changes in the rotation speed of the engine 10 are suppressed to an extremely small value. In the speed ratio control control means 86, the second speed V of the vehicle detected by the vehicle speed detection means 88, in other words, the rotational speed N of the output shaft of the continuously variable transmission 14 is determined.
O and the actual rotational speed Ne of the engine 10 (continuously variable transmission 1
The actual speed ratio e is determined based on the rotational speed Ni) of the input shaft of No. 4, while the target rotational speed ratio e' for making the actual rotational speed Ne match the target rotational speed Ne' is determined, The speed ratio of the continuously variable transmission 14 is changed by the speed ratio adjusting means 90 so that the difference between e and e' becomes zero. The speed ratio adjusting means 90 supplies a speed ratio signal SS to the speed ratio control valve 38 to change the speed ratio e of the belt type continuously variable transmission 14.

On the other hand, in the engine torque detection means 92, the actual rotational speed of the engine 10 is determined based on the pre-stored relationship shown in FIG. The output torque T of is detected. In the line pressure determination means 94, from a predetermined relationship, the actual torque T9 of the engine 10, the actual rotational speed Ne of the engine 10 detected by the rotational speed detection means 80, the actual rotational speed Ne of the engine 10 detected by the vehicle speed detection means 88, and the The line pressure of the oil passage 46 is determined based on the output shaft rotational speed NO of the step-change transmission 14. The pressure regulating valve adjusting means 96 receives a pressure regulating signal sp which is a control voltage for maintaining the line oil pressure determined by the line pressure determining means 94.
is supplied to the pressure regulating valve 44. As a result, the line oil pressure is maintained at a minimum pressure within a range where the transmission belt 24 does not slip, thereby preventing power loss and deterioration of the durability of the transmission belt 24 due to excessive line oil pressure.

The operation of this embodiment will be explained below according to the flowchart of FIG.

First, step S1 is executed, and the throttle valve 540 function θ and the actual rotational speed Ne of the engine 10 are determined by the signal T.
It is read based on H and SE and stored in the RAM 68. Then, step S2 corresponding to the target rotational speed determining means 76 is executed, and the target rotational speed Ne' is calculated based on the opening degree θ of the throttle valve 54 from the predetermined relationship shown in FIG. Then, step S3 corresponding to the deceleration 4 state determining means 78 is executed,
It is determined whether the actual rotational speed Ne is smaller than the target rotational speed Ne'. If the target rotational speed Ne' is larger than the actual rotational speed Ne, the vehicle is not in a deceleration state, so the speed ratio control routine of step S6 is executed.
If the actual rotational speed Ne is larger than the target rotational speed Ne', the vehicle is in a deceleration state, so step S4 corresponding to the rotational region determining means 82 is executed, and the actual rotational speed Ne is predetermined. It is determined whether the rotation speed Ne is smaller than a certain rotation speed change suppression control determination rotation speed Ne. The rotational speed change suppression control discrimination rotational speed Ne□ is set as shown in FIG. 7 with respect to the target rotational speed Ne'. That is, if Ne1 is too large, drivability and fuel *1 economy during re-acceleration are improved, but on the other hand, Ne becomes too large during deceleration, causing problems such as excessive engine braking and noise. Furthermore, if NO is set to a small value, drivability and fuel economy during re-acceleration are likely to be impaired, so Ne1 is set at a point where these two are balanced. In step S4,
If the actual rotational speed Ne is larger than Ne, the speed ratio control routine of step S6 is executed, but if the actual rotational speed Ne is smaller than Ne□, it corresponds to the rotational speed change suppressing means 84. Step S5 is executed, and the contents of the target rotational speed Ne' are replaced with a value Ne-α that is slightly smaller than the actual rotational speed Ne. As a result of the content of the target rotation speed Ne' being set to a value Ne-α that is slightly smaller than the actual engine rotation speed Ne, the rotation of the engine 10 is changed in the speed ratio control routine of step S6 that is executed following step S5. Changes in speed will be suppressed to an extremely small level.

The speed ratio control routine described above is executed as shown in FIG.

That is, step SRI is first executed, and the rotation signal S
Based on E and SC, the rotational speed Ni of the input shaft 16 and the rotational speed No of the output shaft 20 of the continuously variable transmission 14 are calculated. Then, step SR2 is executed, and the actual speed ratio e (=No/Ni) of the continuously variable transmission 14 is calculated based on the rotational speed N6j of the input shaft I6 and the rotational speed No of the output shaft 20. At the same time, step SR3 is executed, and the target speed ratio e
'(=No/N i ') is calculated. Next, step SR4 is executed, and the target speed ratio e' becomes the minimum speed ratio e.
It is determined whether or not the target speed ratio e' is smaller than min. If it is smaller, step SR5 is executed and the content of the target speed ratio e' is set as the minimum speed ratio emin, but if it is not smaller, step SR6 is executed and the target speed ratio e' is set as the minimum speed ratio emin. It is determined whether the speed ratio e' is smaller than the maximum speed ratio emax. If the target speed ratio e' is not smaller than the maximum speed ratio emax, step SR7 is executed and the content of the target speed ratio e' is set to the maximum speed ratio emax, but if it is smaller, the next step SR8 is executed. executed.

In step SR8, the deviation Δe between the target speed ratio e' and the actual speed ratio e is calculated, and in step SR9, the flow rate control voltage Vf, which is the control amount to make the deviation Δe zero, is calculated by the following formula ( ]), and a speed ratio signal SS representing the flow rate control voltage Vf7 is supplied to the speed ratio control valve 38 to adjust the speed ratio e of the continuously variable transmission 14.

That is, steps SRI to SR8 correspond to the speed ratio control means 86, and step SR9 corresponds to the speed ratio adjustment means 90.

Vf=, -e + 2-Δe --fil However, K1.
2 is a constant.

Next, step 5RIO is executed, which corresponds to the engine torque detection means 92, and the actual torque T of the engine 10 is calculated from the predetermined relationship shown in FIG. Then, step 5 corresponds to the line pressure determining means 94 and the pressure regulating valve adjusting means 96.
RII is executed, and the pressure regulating valve control voltage Vp, which is a control amount for controlling the line pressure, is calculated according to the following formula (2) stored in advance, and the pressure regulating signal SP representing the voltage Vp is applied to the pressure regulating valve. 44.

8 Vp=f (T, Ni, No) -121 Thus,
According to this embodiment, when the vehicle is decelerating, the engine 1
When the actual rotational speed Ne of 0 becomes lower than the rotational speed change suppression control determination rotational speed Ne, the contents of the target rotational speed Ne' are set to Ne-α in step 85.
The deviation Δe calculated in step SR8 is an extremely small value. Therefore, the control amount Vf calculated in step SR9 is almost enough to maintain the current speed ratio [the first term in equation (1)], so that the change in the rotational speed of the engine 10 is kept at an extremely small value. suppressed.

Therefore, as shown by the solid line in FIG. 9, the actual engine rotational speed Ne during vehicle deceleration is maintained relatively high. Section A in FIG. 9 shows this state. As a result, during the subsequent re-acceleration, the range of increase in the rotational speed Ne and the range of change in the speed ratio e for making the engine rotational speed Ne match the target rotational speed Ne' are reduced, and the continuously variable transmission 1
Since the speed ratio change speed of No. 4 and the speed ratio change time of No. 4 are reduced, a decrease in the transmission efficiency of the continuously variable transmission 14 is significantly suppressed compared to the conventional case shown by the broken line in FIG. Drivability (re-acceleration performance) and fuel economy when the vehicle is re-accelerated are significantly improved. Furthermore, even if the engine speed Ne is maintained higher than before when the vehicle is decelerating, the accelerator operation amount is essentially zero in such a case, so this will not impair fuel economy. be. Furthermore, in a continuously variable transmission, the more the speed ratio is changed, the more the transmission efficiency inevitably decreases in the process.

Next, another embodiment of the present invention will be described. In the following description, parts common to those in the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 10, steps S7 and S8 may be inserted between the aforementioned steps S3 and 84 so that the rotational speed change suppression control discrimination rotational speed Ne1 is determined in advance according to the vehicle speed. It's good. That is, in step S7, the actual vehicle speed V is determined based on the signal 0 SC, and in step S8, the rotation speed change suppression control discrimination rotation speed Nei corresponding to the vehicle speed V is determined based on the predetermined relationship shown in FIG. is determined. Note that the two-dot chain line in FIG. 11 is the optimum value during road loading (during an experiment in which running resistance is applied using a dynamometer).

According to this embodiment, since the rotational speed change suppression control determination rotational speed Ne□ is determined to be a large value in accordance with the increase in the actual vehicle speed, favorable fuel economy is achieved in the re-acceleration state that follows the vehicle deceleration. There is an advantage that the re-acceleration performance can be further improved while maintaining the same. FIG. 12 is a block diagram of this embodiment, and steps S7 and S8 correspond to the rotation speed change suppression control discrimination rotation speed determination means 98.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, although the belt-type continuously variable transmission 14 has been described in the above-described embodiment, other types of continuously variable transmissions may be used.

Further, in the above embodiment, the opening degree θ of the throttle valve 54 is used to detect the required load of the engine 10, but the operating amount θ of the accelerator pedal 52 is -operated amount engine 1
It may be an amount such as zero intake pipe negative pressure. In short, any amount that represents the required load amount of the engine 10 may be used.

Further, in step S5 of the above-described embodiment, the contents of the target rotational speed Ne' are replaced with a value Ne-α that is slightly smaller than the actual engine rotational speed Ne, but the actual rotational speed Ne or the target rotational speed Ne' is the target rotational speed Ne
′ and the actual rotational speed Ne may be added to the value β, which is Ne+β.

Further, in the above embodiment, the deceleration state determining means 78 determines the deceleration state of the vehicle based on the fact that the actual rotational speed Ne is larger than the target rotational speed Ne'. The deceleration state of the vehicle may be determined based on the fact that the value subtracted from the previous vehicle speed (2) is positive.

The above-mentioned embodiment is merely an embodiment of the present invention, and various modifications may be made to the present invention without departing from its scope.

[Brief explanation of the drawing]

FIG. 1 shows the claim I1 of the present invention. FIG. 2 is a configuration diagram of a continuously variable transmission for a vehicle to which an embodiment of the present invention is applied. FIG. 3 is a control block diagram of the embodiment of FIG. 2. FIG. 4 is a diagram showing the relationship between the target rotational speed and the I knob opening degree by λ·1). FIG. 5 is a diagram showing output torque characteristics with respect to engine rotational speed using number 5, 1 slot, and torque valve opening as parameters. Figures 6 and 8 are 2I\! This is a flowchart 1 for explaining the operation of the embodiment I. Figure 7: Throttle valve opening θ and engine speed N
FIG. 3 is a diagram showing the relative relationship between the rotational speed change suppression control discrimination rotational speed Ne□ and the 1'1 standard rotational speed Ne' in a two-dimensional chart with e. FIG. 9 is a time chart showing the operation of the embodiment shown in FIG. FIGS. 10 and 12 are diagrams and control block diagrams showing essential parts of a feature 30-1 in another embodiment of the present invention. FIG. 11 is a diagram showing the relationship between the vehicle speed and the rotation speed for determining rotation speed change suppression control. 10: Engine 14: (Hell 1 set) Continuously variable transmission 56: Throat sensor (required load amount detection means) 60:
Rotation sensor (rotation speed detection means) 76: Target rotation speed determination means 78 - Deceleration state determination means 82: Rotation region determination means 84 - Rotation speed change suppression means 90: Speed ratio adjustment means Applicant: Toyota Motor Corporation 4 FIG. Figure 5 Engine rotation l Good Figure 6 Figure 10 Slot 7mm hakama koto (θ

Claims (1)

[Scope of Claims] A continuously variable transmission for a vehicle that continuously changes the rotation of an engine and transmits the same to wheels, comprising a rotation speed detection means for detecting the rotation of the engine, and a required load amount required for the engine. a target rotation speed determining means that sequentially determines a target rotation speed of the engine based on the required load amount from a predetermined relationship; a speed ratio adjusting means for adjusting the speed ratio of the continuously variable transmission so as to match the speed ratio of the continuously variable transmission, comprising: a deceleration state determining means for determining a deceleration state of the vehicle; and a deceleration state determining means for determining the deceleration state of the vehicle; a rotation range determining means for determining that the actual rotation speed is in a rotation range lower than a predetermined rotation speed change suppression control determination rotation speed; and when the vehicle is in a deceleration state and the actual rotation speed of the engine is is lower than the rotational speed change suppression control determination rotational speed, the engine ratio control device.