JPS6353344A - Speed change controlling method for continuously variable transmission for vehicle - Google Patents

Abstract

PURPOSE:To improve the calculation accuracy of the estimated acceleration by calculating the transmission gear ratio changing speed as a sum of a component corresponding to the estimated acceleration and a component corresponding to the target changing speed of the engine rotating speed and using this transmission gear ratio changing speed as a control value. CONSTITUTION:The estimated acceleration is calculated from the excess horsepower of an engine calculated based on the engine unit output corrected with the transmission efficiency, and the transmission gear ratio changing speed is calculated based on this estimated acceleration, the target changing speed of the engine rotating speed obtained from the indicator indicating the driver's intention for acceleration or deceleration, the vehicle speed, and the engine rotating speed. Speed change control is performed using this calculated transmission gear ratio changing speed as a control value. Accordingly, the calculating accuracy of the estimated acceleration is improved, and as a result the control accuracy can be improved.

Description

[Detailed description of the invention] A0 Purpose of invention (1) Industrial application field The present invention relates to a speed change control method for a continuously variable transmission for a vehicle.

(2) Conventional technology Conventionally, in such a control method, (a) the tel gear ratio is adjusted to the target value so that the engine rotation speed becomes the target value, (bl the rate of change of the engine rotation speed becomes the target value) It is common to perform control i1D so that

(3) Problems to be Solved by the Invention However, the above-mentioned conventional method does not take into account the acceleration predicted from the surplus horsepower of the engine.

For this reason, the amount of change in the gear ratio tends to be more than or less than necessary, and at low speeds (a) there is a shift delay due to the small gear ratio change speed during shift control on the "large" side of the gear ratio, and the resulting abnormality; feeling (deterioration of responsiveness) or (b
) When controlling the gear ratio on the "small" side, fuel consumption may deteriorate and discomfort may occur as the engine speed increases, or (
c) Hunting of the engine speed occurs due to the small change rate of the gear ratio during shift control on the "large" side of the gear ratio, and (d) deterioration of fuel efficiency due to a drop in efficiency due to overshifting during deceleration. do.

The present invention has been made in view of the above circumstances, and calculates the speed ratio change speed as the sum of a component corresponding to the predicted acceleration and a component corresponding to the target speed change of the engine speed, and calculates the speed change ratio. By using the rate of change as the control value,
It is an object of the present invention to provide a speed change control method for a continuously variable transmission for a vehicle, which solves the above problems, improves the calculation accuracy of predicted acceleration, and improves the control accuracy.

B1 Structure of the Invention fll Means for Solving the Problems According to the method of the present invention, the predicted acceleration 9 is calculated from the engine margin, which is calculated based on the single engine output corrected by the mission efficiency, and the predicted acceleration is The target change speed direction of the engine speed obtained from the acceleration 9 and an index indicating the driver's intention to accelerate or decelerate.

Based on the vehicle speed V and engine rotation speed N, calculate the speed ratio change speed i from the following formula, and
(2) C: Constant The speed change control is performed using the calculated gear ratio changing speed l as a control value.

(2) Effect Since the speed ratio change speed is calculated as the sum of the component corresponding to the predicted acceleration and the component corresponding to the target speed change of the engine speed, the speed ratio change speed becomes appropriate. Moreover, the calculation accuracy is improved because the engine output is corrected by the mission efficiency to calculate the surplus horsepower.

(3) Embodiment Below, an embodiment of the present invention will be explained with reference to the drawings. First, in FIG. A variable displacement hydraulic pump 2 and a variable displacement hydraulic motor 4 having an output shaft 3 for driving wheels W and disposed on the same axis as the hydraulic pump 2 are connected to each other to form a hydraulic closed path 5. consists of being connected. 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 a high pressure oil path 5h, and the discharge port of the hydraulic motor 4 and the suction port of the hydraulic pump 2 are connected to each other by a low pressure oil path 51. connected to.

A short-circuit path 6 is connected to the high-pressure oil path 5h and the low-pressure oil path 512, and a clutch valve 7 is provided in the middle of this short-circuit path 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 5 through check valves 9 and 10.
h, 51, and hydraulic oil pumped up from the oil tank 12 is supplied to the hydraulic closed circuit 5 to replenish the shortage. Furthermore, a relief valve 13 is provided between the suction and discharge ports of the replenishment pump 8.

The clutch valve 7 is controlled to open and close 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.

Control of the gear ratio i is obtained by continuously changing the capacity of the hydraulic motor 4 using the hydraulic cylinder 15, while the hydraulic pump 2 discharges a constant capacity. For example, when the capacity of the hydraulic motor 4 is changed to the "large" side, the gear ratio i changes to "large" (!1!I), and when the capacity of the hydraulic motor 4 is changed to the "small" side, the gear ratio i changes to "large" (!1!I). Changes to the "small" side.

This provides continuously variable speed between the engine E and wheels W of the vehicle.

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 link 1.
It is connected to a hydraulic cylinder 15 via 6.

The hydraulic cylinder 15 includes a cylinder body 17 , a piston 20 that is slidably fitted into the cylinder body 17 and partitions the inside of the cylinder body 17 into a head chamber 18 and a rond chamber 19 , and a piston 20 that is integrated with the piston 20 and is connected to the cylinder body 17 . The piston loft 21 is connected to the swash plate 4a of the hydraulic motor 4 via a link 16.

In such a connection structure, when the piston 20 moves to the left in the direction of contracting the volume of the Rondo chamber 19, the swash plate 4a of the hydraulic motor 4 tilts in the direction of "increasing" the capacity, changing the gear ratio i.
changes to the "large" side and the piston 20 moves to the right in the direction of contracting the volume of the head chamber 18, the swash plate 4 of the hydraulic motor 4
A is tilted in the direction to make the capacity "small", and the gear ratio i changes to the "small" side.

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 rond chamber 19. Oil road 22
A solenoid valve 24 is interposed between the oil tank 12 and the oil tank 12 . Further, the oil passage 23 is connected to a supply oil passage 25 that is continuous with the high pressure oil passage 5h of the hydraulic closed circuit 5, and the supply oil passage 25 is connected to the oil passage 22 midway through a solenoid valve 26. The quantity solenoid valves 24 and 26 are duty-controlled by a control means 27 such as a microcomputer, and the duty control controls the operating speed of the hydraulic cylinder 15, that is, the rate of change i of the gear ratio i.

The control means 27 is connected to a throttle opening sensor 28, an engine rotation speed sensor 29, an intake negative pressure sensor 30, a vehicle speed sensor 31, a swash plate angle sensor 32 of the hydraulic motor 4, etc. sensor 28~
The operation of the solenoid valves 24 and 26 is controlled according to the speed ratio change speed i calculated based on the speed change ratio i, which is manually inputted from 32 and the like.

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

=□ ...(1)('xv In equation (1), C' is a constant. Also, by differentiating equation (1) with respect to time t to find the gear ratio change speed i, equation (2) become that way.

di I
Ndt C'XV C'XV
In Equation (2), the direction of change speed of the engine speed is expressed as the target speed of change of the engine speed. When binding and C=1/C', it becomes ■2 ■. That is, the speed ratio change speed i is a component 1a(-CXXy)■2 corresponding to acceleration*.

and the target rate of change in engine speed. It is given by the sum of the component i H (= CX -X Q.) corresponding to . At this time, if Ω is the predicted acceleration, then
The predicted acceleration Ω is obtained from the following (4) 2 to (7) 2.

In other words, the output Pe of the engine E alone is the road resistance R
Pe=Rμ+Ra+Pa=(4) where a, air resistance is Ra, and spare horsepower of engine E is Pa. From this equation (4), the surplus horsepower Pa is calculated as Pa-P
e − (R, c++ Ra) = (5), and the surplus horsepower Pa is also expressed by equation (6), where the vehicle weight is W1 engine rotation & 8 m ffi is ΔW.

g 60” 75 this number (6
)2 and the above equation (5), (W+ΔW)x (Vx
l O').

Therefore, the predicted acceleration 9 is the surplus horsepower P of the engine E.
From a to fJ'1F, it is possible, and the surplus horsepower Pa is the (5th
) can be obtained from the formula. On the other hand, the engine speed is within the target rate of change. calculates an index indicating the driver's intention to accelerate or decelerate, for example, the difference ΔN between the target engine speed N0 and the actual engine speed N, and calculates a target change according to the difference ΔN from the viewpoint of driving feeling and fuel consumption. Direction of speed. This can be obtained by preparing a predetermined table.

Here, the control procedure in the control means 27 will be explained. In FIG. 2, in a first step S1, the engine rotational speed N and the vehicle speed (2) are read. In the next second step S2, the surplus horsepower Pa is calculated. The calculation of this surplus horsepower Pa is performed based on equation (5), and the engine single output PC can be obtained from a map as shown in FIG. 3, for example. That is, in FIG. 3, the horizontal axis is the engine rotation speed N, and the vertical axis is the engine output Pe, using a plurality of intake negative pressures P1 to pH indicated with subscripts 1 to 13 as parameters, 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 determined, and as a result, in the third step S3, the predicted acceleration Ω is calculated from the second step (7).
is obtained. Therefore, in the next fourth step S4, the predicted acceleration component 11 of the gear ratio change speed i is calculated.

In the fifth step S5, the target change speed direction of the engine speed is determined. is required. That is, as shown in FIG. 4, the target speed change direction corresponds to the difference ΔN between the target engine speed N0 and the actual engine speed N. is determined in advance, and the target change speed direction corresponds to the difference ΔN. is calculated. Based on this, in the sixth step S6, the engine rotational speed target gear change speed direction of the gear ratio change speed i is determined. component j N corresponding to
is calculated.

Thereafter, in the seventh step S7, the gear ratio change speed i is calculated based on equation (3), and the calculated value is used as the control value.
Control of solenoid valves 24,26 is provided.

By the way, when calculating the surplus horsepower in the second step S2 of FIG. 2, the engine single output Pe obtained in FIG.
is determined regardless of mission efficiency, and must be corrected based on mission efficiency to obtain accurate engine output. This mission efficiency is determined by the engine output Pe and the engine rotational speed N, but to make it more accurate, it is necessary to further correct it by the shift position. In other words, the mission efficiency η9 is the product (η7-
ηmXKμ), and the mission efficiency η
m is given in FIG. 5, and the gear ratio coefficient η is given in FIG.

In Fig. 5, the horizontal axis is the engine speed N, and subscripts 1 to 1
Multiple engine single outputs shown with 3 Pet-PeB
The transmission efficiency ηm is shown on the vertical axis as a parameter, and in FIG. 6, the transmission ratio coefficient η is shown on the vertical axis with the transmission ratio i on the horizontal axis. The maps shown in FIGS. 5 and 6 are prepared in advance.

Therefore, during the calculation at the second step S2 in the flowchart of FIG. 2, the engine output Pe is corrected by a subroutine as shown in FIG. In other words, the first step! In step 1, the engine single output Pe is determined using the above-mentioned FIG. 3, and in the second step 12, the mission efficiency ηm is determined using the map shown in FIG. Next third step! ! 3, the gear ratio i obtained by the swash plate angle sensor 32 is read, and the fourth step l! In step 4, η is calculated as the gear ratio coefficient using the map shown in FIG. Then the fifth
In step 15, the mission efficiency η8 is calculated, and in a sixth step 16, the engine output Pe is corrected based on this mission efficiency η. Therefore, the surplus horsepower Pa and the predicted acceleration Ω can be determined more accurately based on a more accurate engine output.

In addition, the equation (
Assuming that the predicted acceleration 9 obtained from equation 7) is based on a flat road, the predicted acceleration component 11 of the gear ratio change speed i may deviate depending on the road surface conditions, and the engine speed N may rise or fall from the expected value. Unfavorable driving performance may occur. Therefore, the previous predicted acceleration 9fl-5
Based on the difference between the result and the result *7, it is determined whether the running resistance is greater or less than the predicted level, and the difference (*-+
y, , ), the predicted acceleration component i is corrected.

That is, the previous predicted acceleration Q. -3 is obtained from equation <7), and the result 99 is obtained by subtracting the current vehicle speed ■1 from the previous vehicle speed ■7-1 and dividing it by the time Δt.

Vn, -V.

fi 2 Δt As a result, the correction value Δ* is obtained by Δ<Qh−+ −Qn ) xk (k: correction coefficient), and the predicted acceleration component i is corrected using this correction value Δ9.

Therefore, in the fourth step S of the flowchart shown in FIG.
4, when one predicted acceleration component is calculated, the predicted acceleration component i is calculated by a subroutine as shown in FIG.
, are corrected.

In the first step m1, the engine speed Ne, the current vehicle speed Vll, and the previous vehicle speed v7-1 are read, and in the second step m2, 9. , and the third step m
3, Δv= (>, , -+ Qfi) is calculated,
Based on the result, the predicted acceleration component i is corrected as ',1I=-Cx-x(Ω+Δ0)z in the fourth step m4.

Furthermore, the target change speeds of the engine speed obtained in Fig. 4 are shown. Assuming that is based on a flat road surface, when driving on a slope or when the wind is strong, the change speed is within the target speed.

tends to shift. Therefore, the previous predicted target change speed direction. , , -1 and the resulting direction. 7, it is determined whether the running resistance is larger or smaller than the predicted level, and the engine rotational speed target change speed component j N is corrected in accordance with the difference .

In other words, the previous predicted target change speed direction. , , -1 is obtained from the map of FIG. 4, and the result direction. . is obtained by subtracting the current engine speed N1 from the previous engine speed N, , and dividing it by time Δt.

N□, -N, 1 NOfi=Δt This gives the correction value ΔselfΔ勺=IJA-1-direction・), and the engine rotational speed target change speed component 19 is corrected by this correction value 6t .

Therefore, in the sixth step S of the flowchart shown in FIG.
When calculating the engine speed target change rate component 12 in step 6, the engine speed target change rate component 'IN is corrected by a subroutine as shown in FIG.

In the first step q1, the previous engine speed Nfi-
1. The current engine speed N7 and vehicle speed V are read, and in the second step q2, an OK calculation is performed. Further, in the third step q3, Δauto-(auto, -mei.) is calculated, and based on the result, in the fourth step q4, the engine rotational speed target rate of change! 9 is corrected as ■ 1N=cx -x (self+Δmeat) ■.

Next, to explain the operation of this embodiment, the gear ratio change speed i is calculated as the sum of the predicted acceleration component i and the engine rotational speed target change speed component IN, and the speed change ratio i is controlled as a control value. Therefore, the amount of change in the gear ratio can be appropriately controlled. For example, good. When is constant, iN is the song &? in Figure 10. 1 when 1 is constant. is shown by curve B in FIG. 10, and i is shown by curve C.

As is clear from FIG. 10, the predicted acceleration component i,
Compared to conventional systems that do not take into account the gear ratio change speed i on the "large" gear ratio side at low speeds, the gear ratio change speed i on the "large" side is not too small. Hunting will not occur. In addition, when controlling the gear ratio on the "small" side, the engine speed does not jump up, making it possible to avoid deterioration of fuel efficiency and discomfort, as well as preventing a drop in efficiency due to overshifting during deceleration. do not have.

Moreover, since the engine single output Pe used when calculating the predicted acceleration component 1□ is corrected by the mission efficiency η9, the predicted acceleration component 11 can be calculated using a more accurate engine single output Pe, improving control accuracy. improves.

In addition, the predicted acceleration 9 is corrected by the difference between the previous predicted value 94-6 and the result *1, so the predicted acceleration component 11 can be determined according to the road surface condition, and the engine speed N can be changed from the planned value. Avoid misalignment and enjoy excellent driving performance.

Furthermore, the engine speed target change speed direction. is within the previous target la. ,, Since it is corrected by the difference between -1 and the resulting 1, the target engine rotation speed N0
The rate of change approaches . It is possible to reach the target engine rotation speed N0 while avoiding deviation from the preset pattern.

C0 Effects of the Invention As described above, the method of the present invention calculates the predicted acceleration 9 calculated from the engine's surplus horsepower and the target rate of change in engine speed obtained from the index indicating the driver's intention to accelerate or decelerate.
0, the vehicle speed V, and the engine rotation speed N, the speed ratio change speed i is calculated from the following formula, and C: constant.The speed change control is performed using the calculated speed ratio change i as a control value , prevents the delay in shifting to the "large" gear ratio side at low speeds and the accompanying discomfort, and the occurrence of hunting in the engine speed, and also reduces fuel consumption when controlling the shift to the "small" gear ratio side. It is possible to prevent deterioration and discomfort from occurring, and also to prevent deterioration of fuel efficiency during deceleration.

Further, since the predicted acceleration 9 is calculated from the engine surplus horsepower calculated based on the engine single output corrected by the mission efficiency, the calculation accuracy can be improved, and the control accuracy can be improved.

[Brief explanation of the drawing]

The drawings show one 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 the control procedure, and Fig. 3 is a map for determining the engine output. Figure 4 is a map for determining the engine speed target rate of change, Figure 5 is a map for determining mission efficiency, and Figure 6 is a map for determining the gear change coefficient. Figure 7 is a flowchart of a subroutine for correcting engine output, Figure 8 is a flowchart of a subroutine for correcting predicted acceleration, and Figure 9 is a flowchart of a subroutine for correcting a target rate of change in engine speed. , FIG. 10 is a graph showing an example of the change speed of the gear ratio. T: Continuously variable transmission

Claims (1)

[Claims] A predicted acceleration ■ is calculated from the spare horsepower of the engine calculated based on the single engine output corrected by the mission efficiency, and is obtained from the predicted acceleration ■ and an index indicating the driver's intention to accelerate or decelerate. Target rate of change in engine speed ■＿0
Based on the vehicle speed V and engine rotation speed N, calculate the gear ratio change speed ■ from the following formula, ■=-C×(N/V^2)×■+C×(1/V)×■ ＿
0C: Constant A method for controlling a continuously variable transmission for a vehicle, characterized in that the calculated speed ratio change speed ■ is used as a control value to control the speed change.