JPH03149458A - Controller of continuously variable transmission for car - Google Patents

Abstract

PURPOSE:To reduce change gear shock by successively determining an aimed value during transition that continuously changes from a first aimed value determined based on the relationship before switching, to a second aimed value determined based on the new relationship after the switching, according to the difference between it and the second aimed value. CONSTITUTION:The relationship for determining an aimed value for control is switched based on the operation of running characteristic selection of a car by a running mode selection switch 68, in a change gear ratio control means 50 of a belt type continuously variable transmission 16. An aimed value during transition that continuously changes from a first aimed value determined based on the relationship before switching, to a second aimed value determined based on the new relationship after the switching, is successively determined according to the aimed value during transition and the second aimed value, so as to control a gear change ratio of the continuously variable transmission 16. The gear change ratio of the non-stage transmission is slowly controlled so as to achieve the aimed value during transition that continuously changes, and the generation of gear change shock is prevented thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a control device for a continuously variable transmission for a vehicle.

BACKGROUND OF THE INVENTION Vehicles equipped with a continuously variable transmission in which the gear ratio can be changed steplessly are known. In such a vehicle, the target value determined based on the driving state of the vehicle is realized from one relationship selected based on the driver's selection operation from among multiple types of relationships stored in advance. The transmission ratio is adjusted. For example, multiple types of relationships are stored in advance, corresponding to the selection operation positions of low range, second range, and drive range with the shift shooting lever, and the selection operation positions of power driving and economy driving with the driveability selection switch. A target gear ratio or target which is a control target value is determined based on the required output amount such as the actual throttle valve opening and the vehicle speed based on the relationship specified corresponding to the operating position of the vehicle running performance selection operation among multiple types of relationships. The input shaft rotational speed is determined, and the gear ratio is adjusted so that the actual gear ratio or input shaft rotational speed matches the target value, thereby achieving favorable fuel efficiency and driving performance. There is. For example, the control device described in Japanese Patent Application Laid-Open No. 5-138556 is one example.

Problems to be Solved by the Invention By the way, in the control device for a continuously variable transmission for a vehicle as described above, when a new relationship is specified with the vehicle running performance selection operation, the Since the control target value is suddenly changed according to the difference between the control target value determined from the previous relationship and the new control target value determined from the new relationship, sudden changes in the gear ratio of the continuously variable transmission are possible. As a result, a shift shock may occur while the vehicle is running, which may impair running performance. Further, when the above-mentioned relationship is changed in response to a D→L downshift operation, for example, while driving on a frozen road, the engine braking action suddenly becomes thicker, causing the driving wheels to easily slip.

The present invention has been made against the background of the above circumstances,
The purpose of this is to reduce the shift shock caused by the change in the gear ratio of the continuously variable transmission, even if the relationship for determining the control target is switched in connection with the driveability selection operation. An object of the present invention is to provide a control device for a step-change transmission.

Means for Solving the Problems The gist of the present invention to achieve the object is to provide a continuously variable transmission for a vehicle in which the gear ratio is changed steplessly. Control of a continuously variable transmission for a vehicle in which the gear ratio is adjusted so that a target value determined based on a running state of the vehicle is realized based on a relationship corresponding to a running performance selection operation state. (a) When switching the relationship in accordance with the vehicle driveability selection operation, the device continuously changes from a first target value determined from the relationship before switching to a second target value determined from the new relationship after switching. a transition target value determining means for sequentially determining a transition target value that changes to a second target value according to the difference between the transition target value and the second target value; and a gear ratio control means for controlling the gear ratio of the continuously variable transmission.

In this manner, when the relationship for determining the control target value is switched in connection with the vehicle driveability selection operation, the transition target value determining means calculates the value from the relationship before switching. The transition target value that continuously changes from the first target value determined by the change to the second target value determined from the new relationship after switching is determined sequentially according to the difference between the transition target value and the second target value. At the same time, the gear ratio control means controls the gear ratio of the continuously variable transmission so that the target value at the time of transition is realized. For this reason, the gear ratio of the continuously variable transmission is controlled slowly to achieve the continuously changing target value during transition, so sudden changes in the gear ratio of the continuously variable transmission cause a shift shock while the vehicle is running. This prevents the running performance from being impaired due to the occurrence of this problem.

Also, even when the D-L shift down operation is performed and the relationship is changed while driving on a low-friction road surface such as a frozen road,
The engine braking action acts gently, and slipping of the driving wheels is suitably prevented.

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

In FIG. 2, a crankshaft 12 of an engine 10 is connected to a belt type continuously variable transmission 16 via a fluid coupling 14.
is connected to the input shaft 18 of the belt type continuously variable transmission 1.
The output shaft 20 of No. 6 is connected to the drive wheels of the vehicle via a differential gear device (not shown) or the like. Thereby, the rotational force of the engine IO is transmitted to the drive wheels.

The input shaft 18 and output shaft 20 of the belt type continuously variable transmission 16 are provided with variable pulleys 22 and 24 whose effective diameters are variable, and a transmission belt 26 is wound between the variable pulleys 22 and 24. ing. Variable pulley 22
and 24 are fixed rotary bodies 28 and 30 fixed to the input shaft 18 and output shaft 20, and a movable rotary body 32 provided to the input shaft 18 and output shaft 20 so as to be movable in the axial direction but not rotatable around the axes. and 34. By changing the thrust applied from the hydraulic cylinders 36 and 38 to the movable rotors 32 and 34, the groove width formed between the fixed rotors 28 and 30 and the movable rotors 32 and 34; And the diameter of the belt can be changed.

The hydraulic oil collected in the oil tank 40 is fed under pressure by an oil bomb 42, and its pressure is regulated to line oil pressure by a pressure regulating valve 44 controlled by an electronic control device 50, which will be described later. This line oil pressure is supplied via a line oil passage 46 to a secondary hydraulic cylinder 38 that applies thrust to the secondary variable pulley 24 . Normally, the line oil pressure is calculated from a relational expression (not shown) as the output torque T of the engine 10, the gear ratio r of the belt type continuously variable transmission 16 (=rotational speed Ni of the input shaft 18/rotational speed N of the output shaft 20,... ), and the clamping force on the transmission belt 26, in other words, the tension of the transmission belt 26, is maintained at a necessary and sufficient value within a range that does not cause slippage.

The flow rate control valve 48 is a switching valve controlled by the electronic control device 50, and supplies the hydraulic oil in the line oil passage 46 to the primary side hydraulic cylinder 36 to reduce the gear ratio T, or The hydraulic oil in the cylinder 36 is discharged to the drain to increase the gear ratio T.

The intake pipe of the engine IO includes a throttle valve 54 that is opened and closed by an accelerator pedal 52, and a throttle sensor 56 that detects the opening THR of the throttle valve 54.
is provided. The engine 10 is provided with an engine rotation sensor 58 for detecting the engine rotation speed N based on a signal from an ignition circuit or the like. Continuously variable transmission 1
The rotational speeds Ni and N of the input shaft 18 and the output shaft 20 are located near the fixed rotary body 28 on the primary side and the fixed rotary body 30 on the secondary side of 6. A first rotation sensor 60 and a second rotation sensor 62 are provided for detecting uL. A shift lever 64 provided near the seat is provided with a shift sensor 66 for detecting its operating position SHI. The shift lever 64 has a low (L) range;
It is operated to the second (S) range, drive (D) range, neutral (N) range, reverse (R) range, and parking (P) range. A driving mode selection switch 68 is provided in the vehicle interior for manually selecting between a power driving mode and an economy driving mode. In this embodiment, the driving mode selection switch 68 and the shift lever 64 function as vehicle driving performance selection operation means.

Note that the above-mentioned power driving mode is a mode in which the vehicle can run with emphasis on the driving performance of the vehicle, and the above-mentioned economy driving mode is a mode in which driving can be performed with emphasis on economy.

And, in the input port 0 of the electronic control device 50,
A signal representing the throttle opening THR of the throttle valve 54 from the throttle sensor 56 (i.e., a signal representing the required output amount for the engine IO), an engine rotation sensor 58
, a signal representing the engine rotation speed N from the first rotation sensor 60 and the second rotation sensor 62, a signal representing the input shaft rotation speed Ni and the output shaft rotation speed N081 from the shift sensor 66, and a shift operation position SHj from the shift sensor 66. signal representing,
A signal representing the actually selected driving mode S is supplied from the driving mode selection switch 68.

The electronic control device 50 includes a CPU 72, a ROM 74, and a RAM 7.
6, and an output port 8, the CPU 72 processes input signals according to a program stored in advance in the ROM 74 while utilizing the storage function of the RAM 76, and generates a signal for changing the gear ratio T. It outputs to the flow rate control valve 48 via the output port 8, and also outputs a signal for changing the line oil pressure to the pressure regulating valve 44 via the output port 8. In this embodiment, the ROM 74 includes a plurality of W! corresponding to the operation of the shift lever 64 to the low (L) range, second (S) range, and drive (D) range, and the operation of the driving mode selection switch 68 to the power driving mode and the economy driving mode. Data maps representing six types of relationships are stored in advance. The above data map is an optimal curve for operating the engine 10 to achieve fuel efficiency and driving performance. The CPU 72, for example,
The target rotational speed N in'' is determined based on the actual throttle valve opening THR and vehicle speed SPD from one data map selected according to the operation of the shift lever 64 and driving mode selection switch 68, and the actual input shaft rotational speed N1 is determined. The flow rate control valve 48 is driven so as to change the gear ratio T so as to match the target rotational speed N is''.

Next, the main part of the gear ratio control operation of the electronic control device 50 will be explained according to the flowchart of FIG. In this embodiment, the shift lever 64 or the driving mode selection switch 6
Only when the data map is switched in response to the operation 8 and the target rotational speed N iat becomes higher, the transitional target rotational speed N, , 1, which changes gradually, is used.

In step 31, the vehicle speed SPD is calculated based on the output shaft rotational speed N, the reduction ratio of a differential gear device or the like disposed downstream of the belt-type continuously variable transmission 16, the driving wheel radius, etc. At the same time, the shift operation position by the shift lever 64 and the driving mode selection switch 68-
A character variable R representing the driving mode S- selected by
The NG value is determined as shown in FIG. This RNG value is a 3-bit binary number from 0 to 2 in lO base.
, and six types of numerical values representing 3 to 6, which correspond to the data map representing the six types of relationships described above. Then, in this step S1, one relationship corresponding to the RNG value is selected from the six types of relationships previously stored in the ROM 74, and a target value is determined based on the actual throttle opening THR and vehicle speed SPD. The rotational speed Nint'' is determined.

In step S2, it is determined whether the content of the switching flag XMSD is "1" to indicate that the gear ratio control using the transition target rotational speed N i * s' that changes gradually when changing the data map is in progress. be done.

If it is determined in step S2 that the content of the switching flag XMSD is "1", steps 35 and subsequent steps described below are executed to sequentially obtain the target rotational speed N i *m1 at the time of transition. However, if it is determined in step S2 that the contents of SD in the switching flag In other words, it is determined whether the data map for speed ratio control has been switched. If it is determined in step S3 that the data map has not been switched, the target rotational speed N i is determined in step Stt.
The target rotational speed N i e t '' determined in step Sl is adopted as *''. However, step S3
If it is determined that the data map has been switched in step S4, the content of the switching flag XMSD is set to "1", and then in step S5,
The target rotational speed value (first target value) Ni*1' obtained from the data map immediately before switching and the target rotational speed value (second target value) Ni obtained from the new data map after switching.
Target value difference ΔN i e″″ at the time of switching, which is the difference from at′
(=N iat "N ial'") is calculated. In Fig. 4, a data map immediately before switching at a predetermined (for example, 50%) throttle opening THR (for example, a data map for drive range: shown in a dashed line) and a data map immediately before switching at a predetermined (for example, 50%) throttle opening TIR are shown. Data map (e.g. data map for second range:
) is entered in the shift lever 64.
The target value difference ΔN ill of the switching Ii when the drive range is switched from the drive range to the second range is shown.

In the following step S6, it is determined whether the target value difference ΔN 1 n '' at the time of data map switching is zero or negative, in other words, whether or not it is an upshift.

If it is determined in step S6 that it is an upshift, the contents of the flag After that, the target rotation speed N is set in step Stl.
The target rotational speed N in □1 obtained in step S1 is adopted as *n''. Then, in step 312
, the RNG value in the current cycle is RNG, - in preparation for the next cycle. It is said that When steps 311 to S12 are performed in this manner, the target rotational speed is the same as in conventional gear ratio control.

If it is determined in step S6 that it is not an upshift, the target rotational speed N, □8 at the time of transition is determined in step S7 according to the following equation (1), (1
) formula is the target rotational speed N i a *' at the time of transition
'' is a coefficient for determining the speed of approach from N i a 11 to N i n R1, and may be a constant value, but
It may also be a function of vehicle speed SPD. Also, the constant 02 in equation (1)
is, the target rotational speed N i a s″ at the time of transition is N i
n t'', and a relatively small constant value is usually used. If the above constant Ct is zero, the target rotational speed at the time of transition N = a
Since ΔN i becomes smaller as @′ approaches N1.8, it becomes an asymptote and is hardly reached.

N i as """ N i□" +c, ・8 Ni, "10 ct... (1) When the target rotational speed N, □' at the time of transition is determined as described above, N in step S8 , □' is N i n
It is determined whether or not the target rotational speed N i a s''' at the time of transition has reached R8 or more, in other words, whether the target rotational speed N i a s''' at the time of transition has reached N i n '. If the judgment in step S8 is affirmative In this case, the transition of the target rotational speed in the downshift associated with data map switching has been completed, so
Step 39 and subsequent steps are executed. However, if the determination in step S8 is negative, the target rotational speed is in transition during a downshift due to data map switching, so in step SIO the target rotational speed N i R, which is the control target, is set as the target rotational speed at the time of transition. Rotational speed N, □
' is adopted, and the following step S12 is executed.

In this embodiment, by repeatedly executing the above cycle, it is determined in step S3 that the data map has been switched, and that it is determined in step S3 that the switching is a downshift in which the target value difference ΔNi2 becomes positive. If it is determined in S6, in step S7, the target rotational speed N=*s1 at the time of transition is calculated sequentially according to equation (1), and the target rotational speed N, □1 and the actual input shaft rotational speed N are calculated in step S7.
The entrainment speed ratio T is adjusted so that in coincides with in. The target rotational speed N i n sl at the time of the above transition is calculated from equation (1), and as shown in the time chart of FIG. 5, it can be smoothly changed in a logarithmic curve. This effectively prevents a sudden change in the gear ratio γ of the engine 16 from causing a gear change shock due to engine braking while the vehicle is running, thereby impairing running performance. Also, when driving on a low-friction road surface such as an icy road, the shift lever may
Even if 64 is switched from the D range to the L range, and the relationship is switched from the drive range relationship to the low range relationship, the engine braking action is gradually increased and the occurrence of slip in the drive wheels is suitably suppressed. .

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, in the above-mentioned embodiment, the data map is switched in response to the operation of the shift lever 64 or the driving mode selection switch 68, so that the target value difference Δ at the time of switching is
N in” (=N 1+51 ”N is♂)
is positive, in other words, only when the target value is changed in the downshift direction by switching the data map, the target rotational speed Nimm at the time of transition is adopted, and the control target value changes smoothly. However, in addition to or in place of this, the target rotational speed Nias''' at the time of transition is also adopted when the target value is changed in the upshift direction by switching the data map. It is also good.

Further, in the above-mentioned embodiment, the target rotational speed N i at the time of transition
Although a *1 was determined according to equation (1) and was changed exponentially, it may also be changed linearly at a constant rate of change. In short, when changing from N,1'' to N i n Zl, it is only necessary to change continuously rather than abruptly in steps.

Further, in the above-mentioned embodiment, a plurality of types of relationships are stored in advance in accordance with the operating states of the shift lever 64 and the driving mode selection switch 68, and the data map is stored in accordance with the operation of the shift lever 64 and the driving mode selection switch 68. However, the present invention can be applied to a vehicle in which the driving mode selection switch 68 is removed, and even if the driving mode selection switch 68 is provided, the driving mode selection switch 68 can be changed to a position corresponding to the operating position of the shift lever 64. The present invention can also be applied to vehicles in which only numerical data maps are stored.

In addition, in the above-mentioned embodiment, the target rotational speed N ielK was determined from the data map as the control target for the gear ratio control, but the actual belt rotational speed N e w t was determined from the input shaft rotational speed Nm and the output shaft rotational speed N After the gear ratio T of the continuously variable transmission 16 is calculated, the engine l is adjusted along the optimum curve.
A target gear change pressure T1 is determined based on the actual throttle valve opening THR and vehicle speed SPD from a pre-stored data map for operating the engine, and this target gear ratio TI'
The gear ratio T of the belt-type continuously variable gear ratio 16 may be adjusted so that the actual gear ratio T matches the target gear ratio T''', target rotational speed Nin'', and vehicle speed SP.
Output shaft rotation speed N corresponding to D. Between 1%, T'''
=Nout/Nt," Therefore, the speed ratio control described above and the speed ratio control of the above-described embodiment are substantially the same.

Further, in the above embodiment, the opening degree THR of the throttle valve 54 for adjusting the output of the engine 10 was used as a parameter for determining the target rotational speed N i a 9, but instead of that, the accelerator pedal , the operation amount of a fuel injection amount adjustment lever, etc., the intake pipe negative pressure, and the fuel injection amount may be used as the amount representing the engine output amount.

Furthermore, although the belt-type continuously variable transmission a16 was employed in the above-mentioned embodiment, other types such as a traction type continuously variable transmission may be used.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the main part of the gear ratio control operation in the embodiment shown in FIG. FIG. 2 is a block diagram showing a power transmission mechanism and a gear ratio control mechanism of a vehicle according to an embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the RNG value used to explain the operation of FIG. 1 and the operating states of the shift lever and the driving mode selection switch. FIG. 4 is a diagram illustrating a change in the target value accompanying a downshift operation of the shift lever in the explanation of the operation in FIG. 1. FIG. 5 is a time chart illustrating the operation of the embodiment shown in FIG. lO: Engine 16: Belt type continuously variable transmission 50: Electronic control unit (gear ratio control means) Step S Ani transition target value determination means N! sa,”:Target rotational speed at transition NAl”:
1st target value N i @□1: 2nd target value Applicant Toyota Motor Corporation 111m1 No. 3111 1 RNGla 11114! S & car detour

Claims (1)

[Scope of Claims] In a continuously variable transmission for a vehicle in which the gear ratio is changed steplessly, the running performance of the vehicle is determined based on one relation corresponding to a vehicle running performance selection operation state among a plurality of pre-stored relations. A control device for a continuously variable transmission for a vehicle in which the gear ratio is adjusted so that a target value determined based on a state is realized, the control device being a control device for a continuously variable transmission for a vehicle, the control device being a control device for a continuously variable transmission for a vehicle in which the gear ratio is adjusted so that a target value determined based on a state is realized, , the transition target value that continuously changes from the first target value determined from the relationship before switching to the second target value determined from the new relationship after switching, is calculated by combining the transition target value and the second target value.
A transition target value determining unit that sequentially determines the target value according to the difference from the target value, and a gear ratio control unit that controls the gear ratio of the continuously variable transmission so that the transition target value is realized. A control device for a continuously variable transmission for a vehicle, characterized by: