JPH0721306B2 - Shift control device for continuously variable transmission for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a shift control device for a continuously variable transmission for a vehicle.

(2) Conventional Technology Conventionally, in such a device, (a) the engine speed becomes a target value, (b) the change speed of the engine speed becomes a target value, and (c) the gear ratio is a target. It is general to control the value. In addition, although there is a system that controls the speed change ratio, there is an attempt to roughly estimate the deviation of the engine speed and the speed change ratio.

(3) Problem to be Solved by the Invention In the above-mentioned conventional art, the predicted acceleration predicted from the engine output, the running resistance, the gross vehicle weight, etc. is not taken into consideration at all. Tends to be more or less than necessary, and at low speed, (a) a gear shift delay and a sense of discomfort (deterioration of responsiveness) may occur due to a small gear ratio change speed during gear shift control on the "large" gear ratio side. (B) Deterioration of fuel economy and occurrence of discomfort due to rising engine speed during shift control on the "small" gear ratio side, or (c) Change in gear ratio during shift control on the "high" gear ratio side Hunting of the engine speed may occur due to the low speed, or (d) deterioration of fuel efficiency may occur due to efficiency reduction due to overshifting during deceleration.

The present invention has been made in view of the above circumstances, and calculates a gear ratio change speed as a sum of a component corresponding to a predicted acceleration and a component corresponding to a target change speed of an engine speed, and changes the gear ratio. By using a speed as a control value, it is possible to solve the above problems, and to provide a shift control device for a continuously variable transmission for a vehicle, which improves the calculation accuracy of predicted acceleration, and thus improves the control accuracy. To aim.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the device of the present invention is an engine operation information detecting means for detecting engine operation information including an engine speed N; A vehicle speed sensor for detecting the following; an engine single unit output determining unit that obtains an engine single unit output Pe based on the engine operating information and data of the engine single unit output characteristic; and a correcting unit that corrects the engine single unit output Pe with the mission efficiency; Engine output after correction Pe
A surplus horsepower calculating means for calculating the surplus horsepower Pa of the engine by subtracting the road surface resistance Rμ and the air resistance Ra from the above ;; A predicted acceleration calculation means for calculating the acceleration / deceleration index determination means for determining an index indicating the driver's acceleration / deceleration intention; and a target change speed determination means for determining a target change speed o of the engine speed from the index. the predicted acceleration, the target change rate o of the engine speed, vehicle speed V and = -C × the following equation on the basis of the engine speed ^{N (N / V 2) ×} + C × (1 / V) × o (C: constant ) Gear ratio change speed calculation means for calculating the gear ratio change speed; and operation control means for controlling the operation of the continuously variable transmission so as to change the gear ratio i at the calculated gear ratio change speed. Is characterized by.

(2) Action From the engine characteristics and operating conditions (engine single output corrected by mission efficiency) and vehicle characteristics and running conditions (road surface resistance, air resistance, vehicle speed, total vehicle weight, total engine rotation weight), After calculating the vehicle speed change predicted in the next control cycle, that is, the predicted acceleration, the component corresponding to the predicted acceleration and the target change speed o of the engine speed
The gear ratio change speed is accurately calculated as the sum with the component corresponding to.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, a hydraulic continuously variable transmission T for an automobile.
Is a constant displacement hydraulic pump 2 having an input shaft 1 driven by an engine E, and a variable displacement hydraulic pump having an output shaft 3 for driving wheels W and arranged on the same axis as the hydraulic pump 2. The motor 4 and the motor 4 are connected to each other to form a hydraulic closed circuit 5. That is, the discharge port of the hydraulic pump 2 and the suction port of the hydraulic motor 4 are connected to each other by the high-pressure oil passage 5h, and the discharge port of the hydraulic motor 4 and the hydraulic pump 2 are connected.
The low pressure oil passages 5l mutually connect the suction ports of.

A short circuit 6 is connected to the high pressure oil passage 5h and the low pressure oil passage 5l, and a clutch valve 7 is provided in the middle of the short circuit 6. Further, the discharge port of the replenishment pump 8 driven by the input shaft 1 is connected to the high pressure and low pressure oil passages 5h and 5l via the check valves 9 and 10, and the hydraulic oil pumped from the oil tank 1 supplements the shortage. Therefore, it is supplied to the hydraulic closed circuit 5. Further, a relief valve 13 is provided between the suction and discharge ports of the replenishment pump 8.

The clutch valve 7 is controlled to be opened / closed by an opening / closing control device (not shown), and power transmission between the input shaft 1 and the output shaft 3 is controlled according to the opening degree of the clutch valve 7.

The control of the gear ratio i is obtained by continuously changing the displacement of the hydraulic motor 4 by the hydraulic cylinder 15 for the hydraulic pump 2 that discharges a constant displacement. For example, when the capacity of the hydraulic motor 4 is changed to the "large" side, the gear ratio i is changed to the "large" side, and when the capacity of the hydraulic motor 4 is changed to the "small" side, the gear ratio i is changed to the "small" side. Changes to. As a result, a continuously variable shift between the engine E and the wheels W of the vehicle can be obtained.

The hydraulic motor 4 changes the capacity by changing the inclination angle of the swash plate 4a, and the swash plate 4a is connected to the hydraulic cylinder 15 via the link 16.

The hydraulic cylinder 15 includes a cylinder body 17, a piston 20 slidably fitted into the cylinder body 17 to partition the interior of the cylinder body 17 into a head chamber 18 and a rod chamber 19, and the cylinder body 17 integrated with the piston 20. And a piston rod 21 penetrating an end wall on the rod chamber 19 side of the hydraulic motor 4 in an oil-tight and movable manner.
Is connected to the swash plate 4a.

In such a connecting structure, when the piston 20 moves to the left in the direction of contracting the volume of the rod chamber 19, the swash plate 4a of the hydraulic motor 4 is moved.
Is tilted in the direction of making the capacity "large" and the gear ratio i becomes "large".
When the piston 20 moves to the right in the direction in which the volume of the head chamber 18 is contracted, the swash plate 4a of the hydraulic motor 4 tilts in the direction in which the capacity is "small" and the gear ratio i is in the "small" side. Changes to.

An oil passage 22 is connected to the head chamber 18 of the hydraulic cylinder 15, and an oil passage 23 is connected to the rod chamber 19. A solenoid valve 24 is interposed between the oil passage 22 and the oil tank 12. Oil passage 23
Is connected to a supply oil passage 25 connected to the high pressure oil passage 5h of the hydraulic closed circuit 5, and the supply oil passage 25 is connected to the middle of the oil passage 22 via a solenoid valve 26. The quantity solenoid valves 24, 26 are
The duty is controlled by the control means 27 such as a microcomputer, and the operating speed of the hydraulic cylinder 15, that is, the changing speed of the gear ratio i is controlled by the duty control.

The control means 27 is connected to an engine speed sensor 29 and an intake negative pressure sensor 30 as an engine operation information detection means for detecting engine operation information, and a throttle opening sensor 28, a vehicle speed sensor 31 and a hydraulic motor 4 are connected. The swash plate angle sensor 32 and the like are connected. Thus the control means 27
Is an engine single unit output determination means for obtaining the engine single unit output Pe based on the engine operation information and the data of the engine single unit output characteristics, a correction unit for correcting the engine single unit output Pe with the mission efficiency, and a corrected engine single unit output.
A surplus horsepower calculation means for calculating the surplus horsepower Pa of the engine by subtracting the road surface resistance Rμ and the air resistance Ra from Pe, and the prediction of the vehicle based on the surplus horsepower Pa, the vehicle speed V, the total vehicle weight W, and the total engine rotation weight ΔW. Predictive acceleration calculation means for calculating acceleration, acceleration / deceleration index determination means for determining an index indicating acceleration / deceleration intention of the driver, and target change speed determination means for determining a target change speed o of the engine speed from the index. , A speed change ratio change speed calculation means for calculating a speed change ratio change speed based on the predicted acceleration, a target speed change o of the engine speed, a vehicle speed V and an engine speed N, and a solenoid according to the calculated speed change ratio change speed. It has a function as an operation control means for controlling the operation of the valves 24 and 26.

Here, the gear ratio i is represented by the equation (1) when the engine speed is N and the vehicle speed is V.

In the equation (1), C'is a constant. Further, the equation (1) is differentiated with respect to time t to obtain the speed change ratio, and the equation (2) is obtained.

If the change speed of the engine speed in the equation (2) is the target change speed _O of the engine speed and C = 1 / C ′, Becomes That is, the speed change ratio is the component corresponding to the acceleration. And a component corresponding to the target change speed o of the engine speed Will be given as the sum of and. At this time, assuming that is the predicted acceleration, the predicted acceleration is obtained from the following equations (4) to (7).

That is, the output Pe of the engine E alone is the road surface resistance R
When μ, air resistance is Ra, and engine E's surplus horsepower is Pa, Pe = Rμ + Ra + Pa (4) From this equation (4), the surplus horsepower Pa becomes Pa = Pe− (Rμ + Ra) (5). The engine horsepower Pa is energy that can accelerate the entire vehicle at the time of its control cycle. The total vehicle weight is W, and the total engine rotation weight corresponding to the energy used for inertial rotation when the engine is rotating. Is also expressed by the equation (6).

From this equation (6) Is.

Therefore, the predicted acceleration is the horsepower Pa of the engine E.
The surplus horsepower Pa can be calculated from the equation (5). On the other hand, the target change speed o of the engine speed is
An index indicating the driver's intention to accelerate or decelerate, for example, a difference ΔN between the target engine speed No and the actual engine speed N is calculated, and a target change speed o according to the difference ΔN from the viewpoint of driving feeling and fuel consumption. It is obtained by preparing a predetermined table.

Here, the control procedure in the control means 27 will be described. In FIG. 2, in the first step S1, the engine speed N and the vehicle speed V are read. Next second step
In S2, the surplus horsepower Pa is calculated. The calculation of the surplus horsepower Pa is performed based on the equation (5), and the engine unit output Pe is obtained by a map as shown in FIG. 3, for example. That is, in FIG. 3, a plurality of intake negative pressures P _{1 to} P are shown with the engine speed N as the horizontal axis and suffixes 1 to 13.
_The engine output Pe is shown on the vertical axis with ₁₃ as a parameter, and the engine output Pe is determined by the engine speed N and the intake negative pressure.

As a result, the surplus horsepower Pa of the engine E is obtained, and as a result, the predicted acceleration is obtained from the equation (7) in the third step S3. Therefore, in the next fourth step S4, the predicted acceleration component a of the speed change ratio is calculated.

In the fifth step S5, the target change speed o of the engine speed is obtained. That is, as shown in FIG. 4, the difference ΔN between the target engine speed No and the actual engine speed N
The target shift speed o corresponding to is calculated in advance, and the target change speed o corresponding to the difference ΔN is calculated. Based on this, in the sixth step S6, the component _{N of} the gear ratio change speed corresponding to the engine speed target gear change speed o is calculated.

Thereafter, in a seventh step S7, the speed change ratio is calculated based on the equation (3), and the solenoid valves 24, 26 are controlled using the calculated value as a control value.

By the way, when the surplus horsepower is obtained in the second step S2 of FIG. 2, the engine unit output Pe obtained in FIG.
It is determined independently of the mission efficiency, and it is necessary to correct it with the mission efficiency to obtain an accurate engine output. This mission efficiency is based on the engine output Pe
Is determined by the engine rotation speed N, but to be more accurate, it is necessary to further correct the shift position.
That is, the mission efficiency η _M is the engine output Pe
The product of the mission efficiency [eta] m determined by the engine speed N and the gear ratio factor Kη determined by the speed ratio i (η _{M =} ηm × K
μ) and the mission efficiency ηm is
The gear ratio coefficient Kη is given in FIG.

In FIG. 5, the engine speed N is taken as the horizontal axis, and subscripts 1 to 13 are used.
The transmission efficiency ηm is shown on the vertical axis with a plurality of single engine outputs Pe _{1 to} Pe ₁₃ shown with symbols as parameters, and in FIG. 6, the transmission ratio i is shown on the horizontal axis and the transmission ratio coefficient Kη is shown on the vertical axis. Has been done. The maps shown in FIGS. 5 and 6 are prepared in advance.

Therefore, the second step in the flowchart of FIG.
During the calculation of S2, the engine unit output Pe is corrected by the subroutine shown in FIG. That is, in the first step l1, the engine unit output Pe in FIG.
Then, in the second step l2, the mission efficiency ηm is calculated from the map shown in FIG. In the next third step l3,
Read the gear ratio i obtained by the swash plate angle sensor 32,
In the fourth step l4, the gear ratio coefficient Kη is calculated from the map shown in FIG. After that, the mission efficiency η _M is calculated in the fifth step l5, and the engine output Pe is corrected in the sixth step l6 by this mission efficiency η _M. Therefore, the surplus horsepower Pa and the predicted acceleration are more accurately obtained based on the more accurate engine output.

Further, assuming that the predicted acceleration obtained by the expression (7) based on the surplus horsepower Pa calculated by the expression (5) is a flat road reference, the predicted acceleration component a of the gear ratio change speed may deviate depending on the road surface condition. Therefore, it is possible that the engine speed N rises or falls below a planned value and is unfavorable for driving performance. Therefore, the previous predicted acceleration n
_-1 and the result n, it is determined whether the running resistance is larger or smaller than the predicted level, and the difference (n ₋₁ −
The predicted acceleration component a is corrected corresponding to n).

That is, the previous predicted acceleration n ₋₁ is obtained by the equation (7), and the result n is obtained by subtracting the current vehicle speed Vn from the previous vehicle speed n ₋₁ and dividing by the time Δt. is there.

As a result, the correction value Δ is obtained by Δ = (n ₋₁ −n) × k (k: correction coefficient), and the predicted acceleration component a is corrected by this correction value Δ.

Therefore, the fourth step S4 of the flowchart shown in FIG.
When the predicted acceleration component a is calculated,
Predicted acceleration component a by a subroutine as shown in the figure
Is corrected.

In the first step m1, the engine speed Ne and the current vehicle speed V
n, the previous vehicle speed Vn _-1 is read, n is calculated in the second step m2, and Δ = (in the third step m3.
n ₋₁ −n) is calculated, and the predicted acceleration component a is calculated in the fourth step m4 based on the result. Is corrected as.

Further, assuming that the target change speed o of the engine speed obtained in FIG. 4 is a flat road surface reference, the target change speed o tends to shift when traveling on a slope or when wind is strong.
Therefore, the previous predicted target change rate on _-1 and the result
Based on the difference from on, it is determined whether the running resistance is higher or lower than the predicted level, and the engine speed target change speed component _N is corrected according to the difference (on ₋₁ −on).

That is, the previous predicted target change speed on _-1 is obtained from the map in FIG. 4, and the result on is the previous engine speed Nn.
_{-1 minus the} current engine speed Nn is the time Δ
It is obtained by dividing by t.

Thus, the correction value ΔΔ = (n ₋₁ −n) is obtained, and the engine speed target change speed component _N is corrected by this correction value Δ.

Therefore, the sixth step S6 of the flowchart shown in FIG.
When the engine speed target change speed component _N is calculated, the engine speed target change speed component _N is corrected by a subroutine as shown in FIG.

In the first step q1, the previous engine speed Nn _-1 , the current engine speed Nn and the vehicle speed V are read, and in the second step q2, n is calculated. Further, in the third step q3, Δ = ( _N-1 −n) is calculated, and based on the result, the engine speed target change speed _N is calculated in the fourth step q4. Is corrected as.

Next, the operation of this embodiment will be described. The speed ratio change speed is calculated as the sum of the predicted acceleration component a and the engine speed target change speed component _N, and the speed ratio change speed is controlled as a control value. The amount of change in the gear ratio is properly controlled. For example, _N when o is constant is shown by curve A in FIG. 10, a when it is constant is shown by curve B in FIG. 10, and is shown by curve C.

As is clear from FIG. 10, as compared with the conventional one in which the predicted acceleration component a is not taken into consideration, the gear ratio change speed on the “gear” side of the gear ratio is not too small at the time of low speed, and therefore the gear delay Also, there is no discomfort associated therewith and no hunting of the engine speed occurs. Further, the engine speed does not rise up during the shift control on the “small” gear ratio side, it is possible to avoid the deterioration of fuel efficiency and the occurrence of unpleasant sensation, and there is also a case where the efficiency is reduced due to overshifting during deceleration. Absent.

Moreover, since the engine unit output Pe used when calculating the predicted acceleration component a is corrected by the mission efficiency η _M ,
The predicted acceleration component a can be calculated using the more accurate engine unit output Pe, and the control accuracy is improved.

Since the predicted acceleration is corrected by the difference between the previous predicted value n _-1 and the result n, the predicted acceleration component a corresponding to the road surface condition can be obtained, and the engine speed N deviates from the planned value. Excellent driving performance can be avoided.

Further, the engine speed target change speed o is corrected by the difference between the previous target value on ₋₁ and the result n, so that the change speed o approaching the target engine speed No is set in advance regardless of the running condition. It is possible to avoid the deviation from the pattern and reach the target engine speed No.

C. Effects of the Invention As described above, the device of the present invention includes an engine operation information detection unit that detects engine operation information including the engine speed N; a vehicle speed sensor that detects a vehicle speed V; the engine operation information and the engine. Engine single unit output determining means for obtaining engine single unit output Pe based on single unit output characteristic data; Correction unit for correcting engine single unit output Pe with mission efficiency; Road surface resistance R from corrected engine single unit output Pe
a marginal horsepower calculating means for calculating a margin horsepower Pa of the engine by subtracting μ and air resistance Ra; a predicted acceleration of the vehicle is calculated based on the margin horsepower Pa, a vehicle speed V, a total vehicle weight W and a total engine rotation weight ΔW. Predictive acceleration calculating means; acceleration / deceleration index determining means for determining an index indicating acceleration / deceleration intention of the driver; target change speed determining means for determining a target change speed o of the engine speed from the index; , the target change rate o of the engine speed, vehicle speed V and = -C × the following equation on the basis of the engine speed ^{N (N / V 2) ×} + C × (1 / V) × o (C: constant) speed ratio The gear ratio change speed calculation means for calculating the change speed; and the operation control means for controlling the operation of the continuously variable transmission so as to change the gear ratio i at the calculated gear ratio change speed; Characteristics and operating conditions (engine Body speed), vehicle characteristics and running conditions (road surface resistance, vehicle speed, total vehicle weight, total engine rotation weight), the vehicle speed change predicted in the next control cycle, that is, the predicted acceleration is calculated, and this prediction is calculated. The gear ratio change speed can be accurately calculated while taking into consideration both the acceleration and the target change speed o of the engine speed. As a result, the gear change delay to the "large" gear ratio side at low speed and It prevents the occurrence of discomfort and hunting of the engine speed, and also prevents the deterioration of fuel economy and the occurrence of discomfort during the shift control to the "small" gear ratio side. It is possible to prevent the deterioration.

Further, in particular, since the engine single unit output Pe is corrected by the mission efficiency, the calculation accuracy of the predicted acceleration calculated based on the output Pe and the like, and consequently the calculation accuracy of the speed change ratio, is improved, and the control accuracy is improved as a whole. Can be further enhanced.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a circuit diagram showing the configuration of a continuously variable transmission, FIG. 2 is a flowchart showing a control procedure, and FIG. 3 is a map for obtaining an engine output. Fig. 4 is a diagram showing a map for obtaining a target engine speed change rate, Fig. 5 is a map for obtaining a mission efficiency, and Fig. 6 is a map for obtaining a transmission coefficient. FIG. 7 is a flowchart of a subroutine for correcting the engine output, FIG. 8 is a flowchart of a subroutine for correcting the predicted acceleration, and FIG. 9 is a flowchart of a subroutine for correcting the engine speed target change speed. FIG. 10 is a graph showing an example of the speed change ratio. 29 ... Engine speed sensor as engine operating information detecting means, 30 ... Intake negative pressure sensor as engine operating information detecting means, 31 ... Vehicle speed sensor, T ... Continuously variable transmission

Claims (1)

[Claims] 1. Engine operating information detecting means (29, 30) for detecting engine operating information including engine speed N;
A vehicle speed sensor (31) for detecting a vehicle speed V; an engine single unit output determining means for obtaining an engine single unit output Pe based on the engine operating information and output characteristic data of the single engine; Compensation means for :; subtracting road surface resistance Rμ and air resistance Ra from the corrected engine unit output Pe, and the engine surplus horsepower Pa
And a predicted acceleration calculation means for calculating a predicted acceleration of the vehicle based on the surplus horsepower Pa, the vehicle speed V, the total vehicle weight W, and the total engine rotation weight ΔW; Acceleration / deceleration index determining means for determining an index indicating the above; target change speed determining means for determining a target change speed o of the engine speed from the index; and the predicted acceleration, target change speed o of the engine speed, vehicle speed V and based on the engine rotational speed N from the following formula ^{= -C × (N / V 2} ) × + C × (1 / V) × o (C: constant) and the gear ratio change rate calculating means for calculating the speed ratio changing speed; An operation control means for controlling the operation of the continuously variable transmission (T) so as to change the gear ratio i at the calculated gear ratio change speed; apparatus.