JPH0621641B2 - Control device for continuously variable transmission for vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control device for a continuously variable transmission for a vehicle, and in particular,
The present invention relates to a technique for improving drivability on an uphill road or a downhill road with many curves.

2. Description of the Related Art A continuously variable transmission for a vehicle that continuously changes the rotation of an engine and transmits it to driving wheels is known. A vehicle equipped with such a continuously variable transmission has a high fuel consumption rate of the engine when traveling. Since the operating conditions can be selected, higher fuel consumption efficiency can be obtained compared to the conventional vehicle equipped with a stepped transmission, and moreover,
Since the speed ratio (output shaft rotation speed / input shaft rotation speed) can be changed steplessly, there is an advantage that speed shock does not occur. Conventionally, many control devices for controlling the speed ratio of such a continuously variable transmission for vehicles have been proposed, and the basic one is, for example, an accelerator operation amount, etc. The target rotation speed or target speed ratio is determined from the relationship obtained in advance to obtain the optimum fuel consumption rate based on the indicated amount, and the target rotation speed or target speed ratio and the actual input shaft rotation speed or speed of the continuously variable transmission are determined. The control is performed so that the ratio matches. In such a continuously variable transmission control device, generally, in consideration of the fuel consumption rate and drivability centering on a flat road, a predetermined change speed is set so that the actual input shaft rotation speed or speed ratio matches the target value. Can be changed at.

In such a conventional control device, the setting of the change speed of the continuously variable transmission is also set centering on a flat road, so that the acceleration responsiveness of the vehicle is poor on a traveling road with many curves and slopes such as mountain roads. In some cases, sufficient drivability could not be obtained.

On the other hand, a technique of applying engine braking when the vehicle is traveling downhill (Japanese Patent Laid-Open No. 58-191359) and a technique of correcting the target speed ratio to be small when the vehicle is climbing (Japanese Patent Laid-open No. 58-180864) are available. Proposed.

Problems to be Solved by the Invention However, even with such a conventional technique, when the vehicle is traveling on a road with many curves such as a mountain road and many uphills and downhills, the acceleration / deceleration operation must be frequently repeated. Then, the speed ratio changing speed at which the speed ratio is changed becomes a problem rather than the correction of the target speed ratio. That is, in the case of traveling on an uphill road accompanied by a curve, as shown in FIG. 6, when the vehicle approaches a curve while traveling uphill (t ₁
Time point) Normally, the driver releases the accelerator pedal. In this case, the speed ratio is varied to a larger direction of relatively fast speed ratio change speed defined assuming a flat road, if the returned followed by traveling uphill (t ₂ time) is a fairly large speed ratio Therefore, the driving force is insufficient, and the driver has to operate the accelerator pedal greatly. Also, t ₂ after the time, because the rate of change of direction to decrease the speed ratio is also too slow in value set on the assumption flat road, t ₂ time to t ₄ time between must keep large throttle opening. On the other hand, FIG. 7 shows the downhill running after around the curve, and releases the accelerator pedal when exiting a curve at t ₅ point, usually the driver to compensate for the deceleration of a curve, Accelerate operation. At this time, for the same reason as the case of FIG. 6, too small speed ratio than necessary, enters the steady running t ₆ time to t
You have to release the accelerator pedal for the _8th time. Therefore, in the conventional control device, it is necessary to frequently operate the accelerator pedal on a traveling road with many curves such as mountain roads and many uphills and downhills, which deteriorates drivability.
Moreover, sufficient fuel consumption efficiency could not be obtained.

First Means for Solving the Problems The present invention has been made in view of the above circumstances, and the gist of the first invention is as shown in the claim correspondence diagram of FIG. In a continuously variable transmission for a vehicle that continuously changes the rotation of an engine and transmits the rotation to a drive wheel, control for adjusting a speed ratio of the continuously variable transmission based on at least an amount that represents a driver's intention to perform an acceleration / deceleration operation. A device,
(1) a road surface gradient detecting means for detecting a traveling road surface gradient of the vehicle, and (2) when the traveling road surface gradient detected by the road surface gradient detecting means is an uphill slope, a change speed in a direction in which the speed ratio becomes smaller is set. And a speed ratio changing speed control means for adjusting the changing speed in the direction in which the speed ratio is higher than that of the flat road and becomes larger than that of the flat road, to be lower than that of the flat road.

Operation and Effects of First Invention According to this configuration, when the traveling road surface has an upward slope, the changing speed in the direction in which the speed ratio decreases is higher than that in the flat road, and the changing speed in the direction in which the speed ratio increases increases. Since it is made lower than that on a flat road, the speed ratio does not become so large even when the accelerator pedal is returned while approaching the curve while climbing uphill, and sufficient driving force can be obtained in the subsequent uphill climbing run. The time required to reach the appropriate speed ratio is shortened, the operation of the accelerator pedal is eased, and the drivability of the vehicle and the fuel consumption efficiency are suitably improved.

Second Means for Solving Problems A gist of a second invention for solving the problems is a control device similar to the first invention, which is (1) a road surface of the vehicle. Road gradient detecting means for detecting the gradient,
(2) When the traveling road surface slope detected by the road surface slope detecting means is a down slope, the change speed in the direction in which the speed ratio decreases becomes lower than that in the flat road, and the change speed in the direction in which the speed ratio increases increases. Speed ratio changing speed control means for adjusting the speed higher than that of a flat road.

Action and Effect of the Second Invention According to this configuration, when the traveling road surface has a downward slope, the changing speed in the direction in which the speed ratio decreases is lower than that in the flat road, and the changing speed in the direction in which the speed ratio increases. Is higher than that on a flat road, the speed ratio does not become so small even when the accelerator pedal is depressed to compensate for the deceleration when going out of a curve while traveling downhill, and the appropriate speed for the subsequent downhill traveling. The time to reach the ratio is shortened, the accelerator pedal operation is eased, and frequent accelerator operation is unnecessary even when the curve is continuous,
The drivability of the vehicle and the fuel consumption efficiency are preferably improved.

The control side of the speed ratio change speed may be determined by adding or subtracting a constant correction value to the speed ratio change speed when the traveling road surface is flat, depending on whether the traveling road surface gradient is positive or negative. The rate of change may be continuously changed according to the magnitude of the road surface gradient.

Further, the speed ratio change speed control means is preferably an amount representing a road surface slope detected by the road surface slope detecting means and an intention of the driver for acceleration / deceleration such as throttle valve opening and accelerator pedal operation amount. The speed ratio change speed is controlled based on at least one of the change speed of the amount, the vehicle speed, the speed ratio of the continuously variable transmission, and the speed ratio change amount.

Further, the road surface slope detecting means obtains an average value of the road surface slope of the vehicle within a certain time period, and determines the average value as the road surface slope. The traveling road surface gradient may be detected using an inclinometer, but may be calculated based on the output torque of the engine of the vehicle and the acceleration of the vehicle from the relationship obtained in advance. Further, the output torque of the engine may be calculated based on the rotational speed change speed of the engine and the rotational speed change speed of the input side of the continuously variable transmission from the relationship obtained in advance.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 2, a belt type continuously variable transmission 14 is connected to the engine 10 via a clutch 12 such as a magnetic powder type electromagnetic clutch and a centrifugal clutch, and the rotation of the engine 10 is continuously controlled by the belt type continuously variable transmission 14. After the speed is changed in stages, it is transmitted to the drive wheels via a differential speed reducer or the like (not shown). The belt type continuously variable transmission 14 is attached to an input shaft 16 connected to the clutch 12, a variable pulley 18 having a variable effective diameter attached to the input shaft 16, an output shaft 20, and an output shaft 20. A variable pulley 22 having a variable effective diameter, a transmission belt 24 stretched between the variable pulleys 18 and 22, and a hydraulic cylinder 26 that changes the V groove width of the variable pulleys 18 and 22 to change the effective diameter.
And 28. Variable pulleys 18 and 22
Fixed rotors 30 and 32 fixed to the input shaft 16 and the output shaft 20, respectively, and the input shaft 16 and the output shaft 2.
0 so as to be movable in the axial direction and non-rotatable around the axis, respectively, and V between the fixed rotating bodies 30 and 32.
It is composed of movable rotating bodies 34 and 36 that form grooves, respectively, and the movable rotating bodies 34 and 36 are driven in the axial direction by the hydraulic pressure applied to the spaces in the hydraulic cylinders 26 and 28, whereby the transmission belt 24 The hanging diameter (effective diameter) can be continuously changed. The hydraulic cylinder 28 is constantly supplied with the line hydraulic pressure, and the hydraulic oil amount (hydraulic pressure) in the hydraulic cylinder 26 is adjusted by the speed ratio control valve 38 so that the movable rotary bodies 34 and 36 are acted upon. The force balance is changed and the input shaft 16 of the continuously variable transmission is changed.
Also, the speed ratio of the output shaft 20 can be changed.

The line oil pressure is obtained by adjusting the pressure of hydraulic oil pumped from the oil tank 40 by the pump 42 by the line oil pressure adjusting valve 44, and is supplied to the speed ratio control valve 38 and the hydraulic cylinder 28 via the line oil passage 46. ing. The line hydraulic pressure regulating valve 44 includes a linear solenoid driven by a pressure regulating signal SP described later, and a valve element driven by the linear solenoid, and releases the hydraulic fluid pressure-fed from the pump 42 to the oil tank 40. Is adjusted according to the pressure adjusting signal SP to adjust the line hydraulic pressure. The speed ratio control valve 38 is composed of an inflow side flow rate control servo valve 38A and an outflow side flow rate control servo valve 38B. The servo valves 38A and 38B are linear solenoids driven by speed ratio signals SS1 and SS2 described later, respectively, and their linear solenoids. And a valve element driven by a linear solenoid. The inflow side flow rate control servo valve 38A adjusts the amount of hydraulic oil to the hydraulic cylinder 26 by connecting the oil passage 48 communicating with the hydraulic cylinder 26 and the line oil passage 46 to change the flow area. On the other hand, the outflow side flow rate control servo valve 38B communicates the oil passage 48 with the return oil passage 50 to the oil tank 40 to change the flow area thereof, thereby adjusting the amount of hydraulic oil discharged in the hydraulic cylinder 26. That is, the communication between the oil passage 48 and the line oil passage 46 and the oil passage 50 is blocked by the inflow side flow rate control servo valve 38A and the outflow side flow rate control servo valve 38B, so that the amount of hydraulic oil in the hydraulic cylinder 26 becomes constant. In this state, the speed ratio is fixed, while in the state where the oil passage 48 and the line oil passage 46 are communicated with each other by the inflow side flow rate control servo valve 38A, the amount of hydraulic oil in the hydraulic cylinder 26 is increased. As a result, the effective diameter of the variable pulley 18 is increased and the effective diameter of the variable pulley 22 is decreased.
The speed ratio is increased at a changing speed according to the size of S1. On the contrary, when the oil passage 48 and the return oil passage 50 are communicated with each other by the outflow side flow rate control servo valve 38B, the speed ratio is reduced at a changing speed according to the magnitude of the speed ratio signal SS2.

The intake pipe of the engine 10 is provided with a throttle valve 54 that opens and closes in conjunction with the operation of the accelerator pedal 52, and a throttle sensor 56 attached to the throttle valve 54 opens an opening θ of the throttle valve 54.
_A throttle signal TH, which is a voltage corresponding to TH, is supplied to the microcomputer 58. Further, the vehicle is provided with an inclinometer 60 for detecting the traveling road surface gradient, and the inclination signal SK representing the traveling road surface gradient θ is supplied to the microcomputer 58. The input shaft 16 and the output shaft 20 are provided with rotation sensors 62 and 64 for detecting their rotation speeds, respectively. The rotation sensors 62 and 64 detect the rotation of the input shaft 16 and the output shaft 20, respectively. Corresponding pulsed rotation signals SI and S
O is supplied to each of the microcomputers 58.

The microcomputer 58 includes a CPU, RAM, RO
Equipped with M, A / D converter, interface, etc., the CPU processes the input signal supplied while utilizing the storage function of RAM according to the program stored in ROM in advance, and matches the actual speed ratio with the target speed ratio. The speed ratio signals SS1 and SS2 for controlling the flow rate control servo valve 3
It outputs to 8A and 38B, and also outputs the pressure regulation signal SP which shows the pressure of line hydraulic pressure to the line hydraulic pressure regulating valve 44. The speed ratio signals SS1 and SS2 are voltage signals representing the speed ratio changing direction and the speed ratio changing speed, respectively, and become 0 when they match the target speed ratio of the actual speed ratio. Further, the pressure adjusting signal SP supplied to the line hydraulic pressure adjusting valve 44 is determined based on the output torque Te of the engine 10 and the actual speed ratio e from the relationship obtained in advance,
The line oil pressure is required and fully controlled within a range where slippage does not occur between the transmission belt 24 and the variable pulleys 18 and 22, and power loss is reduced as much as possible.

The operation of this embodiment will be described below with reference to the flowchart of FIG. The routine shown in FIG. 3 is executed by interruption at regular time intervals determined along the control cycle, and by executing step SW1 first, an amount representing the running state of the vehicle, for example, The throttle valve opening θ _TH and the vehicle speed v are read according to the throttle signal TH and the rotation signal SO. Next, by executing SW2, the target input shaft shaft rotation speed N ^O _{in of} the belt type continuously variable transmission 14 is obtained based on the throttle valve opening θ _TH and the vehicle speed v from the relation obtained in advance. The relationship used in this step SW2 is that which is obtained in advance so as to obtain high fuel consumption efficiency and drivability of the vehicle, and is stored in advance in the ROM in the microcomputer 58 in the form of a data map or a function. . In step SW3, the road surface gradient α on which the vehicle is actually traveling is read by the tilt signal SK, and in steps SW4 and SW5, the downshift coefficient K ^D and the shift up coefficient are calculated based on the vehicle speed v and the road surface gradient α. K ^U is determined respectively. In steps SW4 and SW5, when the road surface gradient α is a value (positive) indicating an uphill slope, that is, an uphill slope, the shift-down coefficient K ^D is made larger than the value of a normal flat road and the shift-up coefficient K ^U is made smaller. Further, when the road surface slope α is a down slope, that is, a value (negative) indicating a downhill, the downshift coefficient K ^D is made smaller than the value on a normal flat road, and the upshift coefficient K ^U is made larger. Such a calculation is calculated by adding or subtracting a predetermined fixed correction value ΔK to the value of a normal flat road. Here, the shift-down coefficient K ^D and the shift-up coefficient K ^U may increase the change amount as the vehicle speed v increases, and may decrease when the vehicle speed is low. For example, the correction value ΔK is changed according to the relationship shown in FIG. Further, other state quantities such as the current speed ratio e or its changing speed e and the rotation speed N of the input shaft 16 are also included.
_in , accelerator pedal operation amount or change speed thereof, throttle valve opening θ _TH , change speed of throttle valve opening
The correction value ΔK may be corrected by _TH , the vehicle speed v or its acceleration, the steering wheel turning angle, or the like.

In step SW6, the actual rotation speed N _in of the input shaft 16 or the input side variable pulley 18 is read,
In step SW7, it is determined whether the actual rotation speed N _in is higher than the target rotation speed N ^O _in . S
When the determination of W7 is affirmative, step SW8 is executed, and the control value V _{A of} the inflow side flow rate control servo valve 38A is calculated according to the following equation (1).

^{_{V A = K U | N in}} -N O in | ...... (1) and in step SW9 is executed is a control value _{V B} are 0 outflow side flow rate control servo valve 38B. However, if the determination in step SW7 is negative, step SW
10 is executed and the control value V _{B of the} outflow side flow rate control servo valve is
Is calculated according to the following equation (2): V _B = K ^D | N _in −N ^O _in | (2) and the control value V of the inflow side flow control servo valve 38A
_A is set to 0. The control values V _A and V _B thus determined are output to the speed ratio control valve 38 as speed ratio signals SS1 and SS2 in predetermined steps of a main routine (not shown).

By repeatedly executing the above steps, the speed ratio change speed is optimally adjusted according to the road surface gradient, and it is reduced by the accelerator pedal operation on the uphill or downhill road with many curves, which is the initial purpose, and the drivability and fuel economy are reduced. The quality is enhanced. That is, on an uphill road, B in FIG.
As shown in, the speed ratio changing speed in the direction of increasing the speed ratio is reduced, while the speed ratio changing speed in the direction of decreasing the speed ratio is increased. The amount of change in is suppressed. As a result, when the curve is continuous on an uphill road, frequent accelerator operation is eliminated, and at the same time, the drivability and fuel economy of the vehicle are improved. Further, when the vehicle is descending a slope, the rate of change in the direction of decreasing the speed ratio is reduced and the rate of change in the direction of increasing the speed ratio is increased, so that the accelerator operation is eased as shown in FIG. 7B. In addition, the amount of change in speed ratio is also suppressed. As a result, even when the curve is continuous on a downhill road, frequent accelerator operation is eliminated and the drivability and fuel economy of the vehicle are improved.

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

In the above-described embodiment, the road surface gradient is detected by using the inclinometer 60, but instead of the inclinometer 60, it may be provided instead of the above-mentioned step SW3 of steps ST1 and ST2 for calculating the road surface gradient α. Good. That is, the fifth
In step ST1 of FIG determines the actual output torque T of the engine 10 based on the following equation (3) to the speed change speed _in the speed change speed _e and the input shaft 16 of the engine 10, in step ST2, the From the following equation (4), the actual output torque T of the engine 10 and the vehicle acceleration β
The road surface gradient α is calculated based on

T = Te−Ie · e−Icvt · _in (3) where Ie: engine inertia e: engine speed change speed Icvt: inertia of input side rotating body of belt type continuously variable transmission _in : variable pulley speed Rate of change However, γ: radius of driving wheel T: detected torque η: transmission efficiency γ _G : gear ratio of differential reduction gear e: speed ratio μ γ: rolling resistance coefficient W: vehicle weight μ _a : wind loss coefficient A: vehicle front projection Area v: Vehicle speed α Road surface gradient β: Vehicle acceleration g: Gravitational acceleration As described above, this embodiment has the advantage that the inclinometer 60 is not necessary in addition to the same effect as that of the above-described embodiment.

The embodiment of the present invention has been described above with reference to the drawings.
The present invention also applies to other aspects.

For example, in the above embodiment, the target input shaft rotation speed N
^O _in is determined, and the speed ratio is controlled so that the actual input shaft rotational speed N _in coincides with it. However, the target input shaft rotational speed N ^O _in is optimally the speed ratio of the belt type continuously variable transmission 14. The target engine rotation speed or the target speed ratio is determined in place of the target input shaft rotation speed N ^O _in , and the actual engine rotation speed or the speed ratio is It may be controlled so as to match.

Further, in the above-described embodiment, the target input shaft rotation speed N ^O
_While the throttle valve opening is used to determine in, other amounts such as the accelerator pedal operation amount and the intake pipe negative pressure that indicate the driver's intention of the acceleration / deceleration operation may be used.

The above description is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention. FIG. 2 is an explanatory diagram illustrating the configuration of an embodiment of the present invention. FIG. 3 is a flow chart for explaining the operation of the apparatus shown in FIG.
FIG. 4 is a diagram showing the relationship used in the flow chart of FIG. FIG. 5 is a diagram showing a main part of a flow chart in another embodiment of the present invention. FIGS. 6 and 7 are diagrams for explaining the operation of the embodiment of FIG. 1 in comparison with the conventional case. FIG. 6 shows an uphill slope and FIG. 7 shows a downhill slope. 10: engine 14: belt type continuously variable transmission (continuously variable transmission) 60: inclinometer (road surface gradient detection means) step ST1: (road surface gradient detection means) ST2: (road surface gradient detection means) step SW4: (speed ratio Change speed control means) SW5: (speed ratio change speed control means) SW7: (speed ratio change speed control means) SW8: (speed ratio change speed control means) SW10: (speed ratio change speed control means)

Claims (2)

[Claims] 1. A continuously variable transmission for a vehicle, which continuously changes the rotation of an engine and transmits it to driving wheels, based on at least an amount representing a driver's intention to perform an acceleration / deceleration operation. And a road surface gradient detecting means for detecting a traveling road surface gradient of the vehicle, and when the traveling road surface gradient detected by the road surface gradient detecting means is an upward gradient, Continuously variable transmission for a vehicle, comprising: a speed ratio changing speed control means for adjusting a changing speed higher than that of a flat road and a changing speed in a direction in which a speed ratio increases becomes lower than that of a flat road. Control device. 2. A continuously variable transmission for a vehicle, which continuously changes the rotation of an engine and transmits it to driving wheels, based on at least an amount representing a driver's intention to perform an acceleration / deceleration operation. And a road surface slope detecting means for detecting a traveling road surface slope of the vehicle, and a traveling road surface slope detected by the road surface slope detecting means is a downward slope, a speed ratio in a direction in which the speed ratio becomes smaller. And a speed ratio changing speed control means for adjusting the changing speed lower than that of a flat road and increasing the changing speed in the direction in which the speed ratio becomes larger than that of a flat road. Control device.