JPH04165162A - Shift control device for continuously variable transmission for vehicles - Google Patents

Abstract

PURPOSE:To prevent the generation of discomfort due to speed change delay onto the change gear ratio 'large' side at the time of low speed and the generation of engine speed hunting by computing the change gear ratio change speed as the sum of an element corresponding to the predictive acceleration and an element corresponding to the target change speed of engine speed, and setting this as the control value. CONSTITUTION:A throttle opening sensor 28, an engine speed sensor 29, an intake negative pressure sensor 30, a vehicle speed sensor 31, a cam plate angle sensor 32 for a hydraulic motor 4, and the like are connected to a control means 27, and the control means 27 controls the operation of solenoid valves 24, 26 according to the change gear ratio change speed di/dt computed on the basis of signals inputted from these sensors 28-32 and the like. The change gear ratio change speed di/dt is computed from an expression: di/dt=-Cx(N/V<2>) xdV/dt+Cx(1/V)xdN0/dt (C: constant) on the basis of estimated acceleration dV/dt computed from the excess horsepower of an engine, the target change speed dN0/dt of engine speed obtained from a barometer indicating the accelerating/ decelerating will of a driver, vehicle speed V and engine speed N.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a speed change control method for a continuously variable transmission for a vehicle. [0002]

[Conventional technology]

Conventionally, in such a control method, (a) the engine speed is set to the target value, (b) the rate of change of the engine speed is set to the target value, and (C) the gear ratio is set to the target value. It is common to perform control. [0003]

[Problem to be solved by the invention]

However, the conventional method described above does not take into account the acceleration predicted from the engine's surplus horsepower. For this reason, the amount of change in the gear ratio tends to be more or less than necessary,
At low speeds, (a) when the gear ratio is controlled to the "dog" side, the gear ratio change speed is small, resulting in a shift delay and resulting discomfort (deterioration of responsiveness), or (b) if the gear ratio is "small".
(C) When controlling the gear ratio on the "Dog" side, there may be deterioration in fuel efficiency and discomfort due to the engine speed rising, or (C) When controlling the gear ratio on the "Dog" side, the speed of change in the gear ratio may be low. (d) Deterioration of fuel efficiency due to decreased efficiency due to overshifting during deceleration. [0004] 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 change speed of the engine rotation speed, By using the speed ratio change speed 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 setting accuracy of a target rate of change in engine speed, and improves control accuracy. [0005]

[Means to solve the problem]

According to the first feature of the present invention, the predicted acceleration dV/dt calculated from the spare horsepower of the engine and the target rate of change in engine speed dNo/dt obtained from the index indicating the driver's intention to accelerate or decelerate. , based on the vehicle speed V and the engine rotation speed N, the gear ratio change speed d i / d is calculated from the following formula.
Calculate t, d i / d t = CX (N/V
) X d V / d t + CX (1/ V
) X dNo / d tC: constant The speed change is controlled using the calculated gear ratio changing speed d i / d t as a control value, and the target engine speed changing speed dNo / dt is the target engine speed N. The difference ΔN between the actual engine speed N and the driver's intention to accelerate or decelerate is used as an index indicating the driver's intention to accelerate or decelerate, and the target change rate dN of the engine speed is displayed on a map or table according to the difference ΔN.
o/dt is determined in advance. [0006] According to a second feature of the present invention, in addition to the first feature, when the difference ΔN indicates an acceleration state,
Target change rate d of engine speed when ΔN is outside
When the amount of change of No/dt is outside, and ΔN is medium, the amount of change of target change speed dNo/dt of engine speed is large, Δ
When N is large, the target rate of change in engine speed dN
Set the amount of change in o/dt to a small value. [0007] Furthermore, according to a third feature of the present invention, in addition to the second feature, when the difference ΔN indicates a deceleration state, the target rate of change in engine speed dNo/dt: The amount of change in is set smaller than that in the acceleration state. [0008]

【Example】

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, a hydraulic continuously variable transmission T for an automobile is
A constant discharge hydraulic pump 2 having an input shaft 1 driven by an engine E, and a variable displacement hydraulic motor 4 having an output shaft 3 driving wheels W and disposed on the same axis as the hydraulic pump 2 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 a high pressure oil passage 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 passage 5H. are interconnected by [0009] A short-circuit path 6 is connected to the high-pressure oil path 5 and the low-pressure oil path bladder, and a clutch valve 7 is provided in the middle of this short-circuit path 6. In addition, 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 5H1 via check valves 9 and 10.
5L, and hydraulic oil pumped up from the oil tank 12 is supplied to the hydraulic closed path 5 to replenish the shortage. Furthermore, a relief valve 13 is provided between the suction and discharge ports of the replenishment pump 8. [00101] 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. [0011] 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 "dog" side, the gear ratio i changes to the "dog" side, and when the capacity of the hydraulic motor 4 is changed to the "/J1" side, the gear ratio i becomes "small". change to the side. This provides continuously variable speed between the engine E and wheels W of the vehicle. [0012] 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. [0013] 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 rod chamber 19, and is integrated with the piston 20. It consists of a piston rod 21 that oil-tightly and movably penetrates the end wall of the cylinder body 17 on the rod chamber 19 side, and the piston rod 21 is connected to the swash plate 4a of the hydraulic motor 4 via a link 16. [0014] In such a connection 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 tilts in the direction to make the capacity "dog", and the gear ratio i becomes "dog". When the piston 20 moves to the right in the direction of contracting the volume of the head chamber 18, the swash plate 4a of the hydraulic motor 4
is tilted in the direction that makes the capacity r/J1J, and the gear ratio i becomes "
Change to "small" side. [0015] 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. 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 connected to the high pressure oil passage 5I4 of the hydraulic closed circuit 5.
is connected to the middle of the oil passage 22 via a solenoid valve 26. Both solenoid valves 24 and 26 are duty-controlled by a control means 27 such as a microcomputer, and the duty control controls the hydraulic cylinder 15.
, i.e. the speed of change of the gear ratio i, d i / d
t is controlled. [0016] 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. are connected to the control means 27. , are those sensors 28
The operation of the solenoid valves 24 and 26 is controlled according to the gear ratio change speed d i /d t calculated based on signals inputted from the solenoid valves 24 and 32 . [0017]Here, the gear ratio i is expressed by Equation 1, where N is the engine speed and V is the vehicle speed. [0018] i=N/ (C' XV) (1) In the above formula 1, C' is a constant. Further, if Equation 1 is differentiated with respect to time t to determine the gear ratio change speed d i /dt, Equation 2 is obtained. [0019] di/dt-(1/ (C' XV))
dt-(N/(C'XV))xC'Xdv/d
t] (2) In Equation 2, the rate of change in engine speed is dN/dt, and the target change in engine speed d i /
d t=-cx (N/V2) XdV/ d t+
CX (1/V)
/dt corresponding component di/dt (--cx (N
/V2)Xdv/dt), the target change in engine speed is given. At this time, assuming that dV/dt is the predicted acceleration, the predicted acceleration dV/dt can be obtained from Equations 4 to 7. [0020] That is, the output Pe of the engine E alone is equal to the road resistance R
Pe=Rμ+Ra+Pa-(4) where μ is air resistance, Ra is air resistance, and Pa is the spare horsepower of engine E. From this formula 4, the surplus horsepower Pa is calculated as Pa=P
e-(Rμ+Ra) (5). In addition, the spare horsepower Pa of the engine is the energy that can accelerate the entire vehicle at the time of its control cycle, and the total vehicle weight is W, and the engine rotational total weight is △ When W is used, it can also be expressed by Equation 6.

00February Pa-(W+△W)X (1/g)xav/atx (
VxlO/60 ) x (1/75) (6
) Equation 7 is obtained from Equation 6 above. dV/dt=PaXg x[60/((W+ΔW)x(VxlO))]x75・
(7) Therefore, the predicted acceleration dV/dt can be calculated from the surplus horsepower Pa of the engine E, and the predicted acceleration dV/dt can be calculated from the surplus horsepower Pa of the engine E.
a can be obtained from Equation 5. On the other hand, the target rate of change in engine speed dNo/dt is an index indicating the driver's intention to accelerate or decelerate, for example, the target engine speed N. This can be obtained by calculating the difference ΔN between the actual engine speed N and the actual engine speed N, and preparing a table in which the target rate of change dN/dt is determined in advance according to the difference ΔN from the viewpoint of driving feeling and fuel consumption. [0022] Here, the control procedure in the control means 27 will be explained. In FIG. 2, in the second step S2, the engine speed N and the vehicle speed V are adjusted. 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. The single engine output Pe is 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 a plurality of intake negative pressures P are shown with subscripts 1 to 13.
1 to P13 as parameters, the engine single output Pe is shown on the vertical axis, and the engine single output Pe is determined by the engine rotation speed N and the intake negative pressure. [0023] 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 dV/
dt is obtained. Therefore, in the next fourth step S4, the predicted acceleration component di of the gear ratio change speed di/dt is
/dt is calculated. [0024] In the fifth step S5, a target rate of change in engine speed dNo/dt is determined. That is, as shown in FIG. 4, the target engine speed N and the actual engine speed N
The target shift speed dNo/dt corresponding to the difference ΔN is determined in advance, and the target shift speed dNo/dt corresponding to the difference ΔN is determined in advance.
dt is calculated. [0025] In FIG. 4, when the difference ΔN is "+", that is, in an acceleration state, the amount of change in the target rate of change dNo/dt of the engine speed in the region RPL where ΔN is small is small;
Region R where the amount of change in the target change rate dNo/dt of the engine speed in region -1 where ΔN is medium is large and where ΔN is dog
Target rate of change in engine speed of PH″″r dNo/d
The amount of change in t is set to 1 Jz, and the difference ΔN
is "- [In other words, when in the deceleration state, the amount of change in the target rate of change dNo/dt of the engine rotation speed in the region RII'lL where ΔN is /x is the change in the region R1 when in the acceleration state. In the region R4H where ΔN is medium, the engine rotation speed is set smaller than the amount of change in the region RPM when in the acceleration state, and in the region RMH where ΔN is small. target rate of change d
Region R when the amount of change in No/dt is in the acceleration state
tJX is set smaller than the amount of change at 1. [0026] With this setting, in the acceleration state where the accelerator operation amount is small, that is, in the region R hole, the target change speed dNo/d
Since the amount of change in t is small, the driving condition can be stabilized and a good driving feeling can be obtained even when the unevenness of the road surface or when the accelerator pedal is slightly operated against the will. In other words, in the region RPM, it is necessary to increase the engine output with a linear feeling corresponding to the amount of accelerator operation, and for this purpose, the target rate of change dNo/dt is the amount of change that takes into account the output loss associated with the increase in engine speed, and the amount of change in the region RPH Now you can get a stable feeling of acceleration. [0027] Furthermore, since the accelerator pedal is returned when the need for brake operation arises, in the region R where the deceleration is large, if the amount of change in the target change speed dNo/dt is large, the effectiveness of the engine brake may deteriorate, While it would be troublesome if a large change in engine speed occurred, such a problem does not occur because the amount of change is small [00
28] In the next sixth step S6, the gear ratio change speed d i /
A component dlN/dt corresponding to the engine rotational speed target shift speed dNo/dt of dt is calculated. [0029] Thereafter, in a seventh step S7, the gear ratio changing speed d i /d t is calculated based on Equation 3, and the solenoid valves 24 and 26 are controlled using the calculated value as a control value. [0030] By the way, when calculating the surplus horsepower in the second step S2 of FIG. 2, the engine single output Pe obtained in FIG.
This is determined regardless of mission efficiency, and must be corrected based on mission efficiency to obtain accurate engine output. This mission efficiency is the engine output P
To make it more accurate than the force plate, which is determined by e and the engine rotational speed N, it is necessary to further correct the shift position. That is, the mission efficiency ηM is determined by the engine single output Pe and the engine rotation speed N.
The product of the gear ratio coefficient determined by the gear ratio i and η (77M=η
m×μ), and the mission efficiency ηm
is given in FIG. 5, and the gear ratio coefficient η is given in FIG. [0031] In FIG. 5, the horizontal axis represents the engine speed N, and subscripts 1 to 13
A plurality of engine single outputs Pe −Pe1 shown with
The transmission efficiency ηm is shown on the vertical axis with 3 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. [0032] Therefore, the second step S in the flowchart of FIG.
When calculating step 2, the engine single output Pe is corrected by a subroutine as shown in FIG. That is, in the first step L1, the engine single output Pe is determined using FIG. 3 described above, and in the second step L2, the mission efficiency ηm is determined using the map shown in FIG. In the next third step L3, the gear ratio i obtained by the swash plate angle sensor 32 is read, and in the fourth step L4, the gear ratio coefficient η is calculated using the map shown in FIG. Thereafter, in the fifth step L5, the mission efficiency ηM is calculated, and based on this mission efficiency ηM, the engine output Pe is calculated in the sixth step L6.
Make corrections. Therefore, the surplus horsepower Pa and predicted acceleration dV/dt can be determined more accurately based on more accurate engine output. [0033] Furthermore, assuming that the predicted acceleration dV/dt obtained from Equation 7 based on the surplus horsepower Pa obtained from Equation 5 is based on a flat road, the predicted acceleration component di/ of the gear ratio change speed d i / d t dt may deviate depending on road conditions.
Engine speed N may rise or fall from a scheduled value, resulting in unfavorable driving performance. Therefore, the previous predicted acceleration dVn-1/dt and the result dVn/d
t Which difference determines whether the running resistance is higher or lower than the predicted level, and the difference (d Vll-x / dt
−dV /dt), the predicted acceleration component dia/
Correct dt. [0034] In other words, the previous predicted acceleration dV/dt is expressed by Formula 7
The result dV/n-1n dt is the previous vehicle speed n-1 to the current vehicle speed ■. It is obtained by subtracting the value of Δt and dividing the value by the time Δt. [0035] As a result, the correction value Δ(dV/dt) becomes Δ(dV/dt)
t)=(dVn-1/dt-dVn/dt)xk
k: correction coefficient [0036] Therefore, in the fourth step S4 of the flowchart shown in FIG.
When the predicted acceleration component di/dt is calculated, the predicted acceleration component di/dt is corrected by a subroutine as shown in FIG. [0037] In the first step m1, the engine speed Ne, the current vehicle speed V, and the previous vehicle speed (total 1) are read, the second step m2 calculates dV /dt, and the third step m3 calculates Δ( dV/dt) is calculated, and based on the result, in the fourth step m4, the predicted acceleration component di/dt is calculated as dia/dt=-cx(N/V2)X(dV/dt+
ΔdV/dt). [0038] Furthermore, the target rate of change in engine speed dN obtained in FIG.
If o/dt is based on a flat road surface, the target change speed dN/dt tends to deviate when driving on a slope, when the wind is strong, and due to aging of the transmission. Therefore, based on the difference between the previous predicted target rate of change dNon-1/dt and the result dNon/dt, it is determined whether the running resistance, etc. is higher than the predicted level or 7J>, and the difference (d
Non-1/dt-dNon[0039] That is, the previous predicted target change rate dNon-1/dt
is obtained from the map in FIG. 4, and the result dN/dt is obtained by subtracting the current engine speed n N from the previous engine speed Nn-1 and dividing by time Δt. It is obtained by dN/dt=(Nn, -Nn)/Δtn, and the engine rotational speed target change speed component dIN/dt is corrected using this correction value Δ(dN/dt). [0040] Therefore, in the sixth step S6 of the flowchart shown in FIG.
The engine speed target change speed component d i N / d
When calculating t, a subroutine as shown in FIG. 9 calculates the engine rotational speed target change speed component d i N
/dt correction is performed. [0041] In the first step q1, the previous engine rotation speed N
The current engine speed n-1・N and vehicle speed V are read, and in the second step q2, dN/dt is calculated in line n.

n is called out. Furthermore, in the third step q3, Δ(dN/dt)=(dNn,/dt
-dN/dt) is calculated, and based on the result, in the fourth step q4, the engine rotational speed target change rate dI
N / d t is d I N / d t = CX (
1/V) X (dN/dt+Δd
N/dt). [0042] Next, to explain the operation of this embodiment, the gear ratio change speed d i / d t is the predicted acceleration component di/dt, and the engine rotational speed target change speed component d I N / d
t, and its speed ratio change speed d i
/dt is controlled as a control value, so the amount of change in the gear ratio can be appropriately controlled. For example, dN/
d l N / d t when dt is constant is shown by curve A in Figure 10, and di/d when dV/dt is constant.
t is shown by curve B in FIG. 10, and d i /d t is shown by curve C. [0043] As is clear from FIG. 10, the predicted acceleration component di/
Compared to conventional systems that do not take dt into consideration, the gear ratio change speed di/dt on the "dog" side of the gear ratio is not too small at low speeds, and therefore a shift delay and the resulting strange feeling may occur. Hunting of engine speed does 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. [0044] Furthermore, since the engine single output Pe used when calculating the predicted acceleration component di/dt is corrected by the mission efficiency η4, the predicted acceleration component di/dt can be calculated using a more accurate engine single output Pe. [0045] The predicted acceleration dV/dt is equal to the previous predicted value dvn-1.
Since it is corrected by the difference between /dt and the resulting dVn/dt, the predicted acceleration component dia/dt according to the road surface condition
It is possible to obtain excellent driving performance by avoiding deviation of the engine rotational speed N from the planned value. [0046] Furthermore, the engine rotational speed target change rate dN /dt is
Previous target value dNon, -11dt and result dN
/dt, the speed of change dN approaching the target engine speed N regardless of the driving conditions.
/dt can be prevented from deviating from the preset paOO turn, and the target engine speed N can be reached. [0047] Moreover, regarding the target rate of change dN /dt, the difference ΔN between the target engine speed No. and the actual engine speed N is used as an index indicating the driver's intention to accelerate or decelerate, and the difference Δ
Since the target rate of change dNo/dt of the engine speed is predetermined on a map or table according to N, the optimum d i / dt can be obtained depending on the acceleration and deceleration state, improving drivability. can be improved. [0048] Effects of the Invention As described above, according to the first feature of the present invention, the delay in shifting to the "dog" gear ratio at low speeds and the resulting discomfort, and the reduction in engine speed. It is possible to prevent the occurrence of hunting, and also to prevent the deterioration of fuel efficiency and the occurrence of discomfort when changing gear ratios to the "lower" side, and also to prevent the deterioration of fuel economy during deceleration, and furthermore, to prevent the deterioration of fuel consumption during deceleration. [0049] According to the second feature of the present invention, it is possible to obtain an appropriate transmission ratio change speed according to the deceleration state and improve drivability. It is possible to obtain a target change rate of 100% and obtain a better driving feeling under acceleration. [0050]Furthermore, according to the third feature of the present invention, it is possible to obtain a target rate of change in engine speed that appropriately corresponds to the deceleration state, and to obtain a better driving feeling in the deceleration state.

[Brief explanation of drawings]

[Figure 1] FIG. 2 is a circuit diagram showing the configuration of a continuously variable transmission.

[Figure 2] It is a flowchart which shows a control procedure.

[Figure 3] FIG. 3 is a diagram showing a map for determining engine output.

FIG. 4 is a diagram showing a map for determining the engine rotational speed target rate of change.

[Figure 5] FIG. 3 is a diagram showing a map for determining mission efficiency.

[Figure 6] FIG. 3 is a diagram showing a map for determining a speed change coefficient.

FIG. 7 is a flowchart I of a subroutine for correcting engine output.

FIG. 8 is a flowchart of a subroutine for correcting predicted acceleration.

FIG. 9 is a flowchart of a subroutine for correcting the engine rotational speed target rate of change.

[Figure 10] It is a graph which shows an example of the speed ratio change speed.

[Explanation of symbols]

Continuously variable transmission

[Document core]

drawing

[Figure 1]

[Figure 5] x 1 o'

[Figure 6]

Claims (3)

[Claims] Claim 1: Predicted acceleration dV/dt calculated from engine surplus horsepower and target rate of change in engine speed dN_0/d obtained from an index indicating the driver's intention to accelerate or decelerate.
t, vehicle speed V, and engine rotation speed N, calculate the gear ratio change speed di/dt from the following formula, and calculate di/dt
=-C×(N/V^2)×dV/dt+C×(1/V)
×dN_0/dtC: constant The speed change is controlled using the calculated gear ratio change rate di/dt as a control value, and the target change rate of engine speed dN_0/dt is as follows:
The difference ΔN between the target engine speed N_0 and the actual engine speed N is used as an index indicating the driver's intention to accelerate or decelerate, and the target engine speed change rate dN_0/dt is displayed on a map or table according to the difference ΔN. 1. A method for controlling a speed change of a continuously variable transmission for a vehicle, characterized in that: is determined in advance. 2. When the difference ΔN indicates an acceleration state, when ΔN is small, the amount of change in the target rate of change dN_0/dt of the engine speed is small, and when ΔN is medium, the amount of change in the target rate of change dN_0/dt is small; 2. The apparatus according to claim 1, wherein the amount of change in the target rate of change dN_0/dt of the engine speed is set to be large, and when ΔN is large, the amount of change in the target rate of change dN_0/dt of the engine speed is set to be small. A method for controlling the speed change of a continuously variable transmission for a vehicle. 3. When the difference ΔN indicates a deceleration state, the amount of change in the target rate of change dN_0/dt of the engine rotational speed is set to be smaller than when the engine speed is in an acceleration state. Item 2. A method for controlling a continuously variable transmission for a vehicle according to item 2.