JP2002213599A - Speed change control system for vehicle continuously variable transmission with vehicle speed control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of vehicle speed control performance corresponding to a speed reduction request when a downshift is caused in low response corresponding to the speed reduction request while a constant speed running device is in operate. SOLUTION: A speed change ratio command value DRATIOCVT(t) under a normal traveling is normally selected and changed to a constant traveling command value DRATIOLPF(t) for the constant traveling is selected by a flag from a 520 to a broken line position, to determine a final speed change ratio command value DRTO(t) in 71. A NINCOM-ACC in the case of positive (driving) dFC(t) and NIN-COM-DEC is selected in the case of negative (breaking) dFC(t) to determine final transmission input speed command value NIN-COM in 547. Since a block 549 has a time constant Tnc increasing from 0 corresponding to a rise of VA(t) and calculates DRATIOLPF(t) through DRATIO(t), speed change response of a continuously variable transmission under a low vehicle speed condition is quick to prevent deterioration of vehicle speed control performance corresponding to a speed reduction request.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed control device for maintaining the vehicle speed at a set vehicle speed by operating the braking / driving force of a wheel and / or the speed ratio of a continuously variable transmission, particularly during deceleration. The present invention relates to a shift control device for a continuously variable transmission.

[0002]

2. Description of the Related Art A speed change response defined by a follow-up response of an actual speed ratio to a speed ratio command value of a continuously variable transmission greatly affects the speed change characteristics of a continuously variable transmission. On the other hand, it has a sporty shift characteristic with high speed.On the other hand, when sudden acceleration or sudden deceleration is performed, a shift shock may be felt even though it is a continuously variable transmission. Although it has no smooth shifting characteristics, it does not allow for sporty running with a crisp feeling.

[0003] Conventionally, as described in, for example, JP-A-2000-97328, the shift response of a continuously variable transmission is set so as to have a first-order lag of a predetermined time constant, and this time constant is switched according to running conditions. Technologies have been proposed. By the way, in a vehicle provided with a vehicle speed control device (also referred to as a constant speed traveling device) that maintains the vehicle speed at a set vehicle speed by operating the braking / driving force of the wheels and / or the speed ratio of the continuously variable transmission, For driver's command and inter-vehicle distance control,
If it becomes necessary to decelerate the vehicle due to a decrease in the set vehicle speed during the operation of the vehicle speed control device, the required deceleration cannot be obtained only by lowering the output of the prime mover (fully closing the throttle opening). A request may be made to downshift the transmission such that the gear ratio is a lower gear ratio.

At this time, by using the technology described in the above-mentioned document and making the speed change response higher than the speed ratio change indicated by the broken line in FIG. 16 and rapidly changing the speed ratio as indicated by the dashed line, the engine speed is reduced. And the driving torque also changes more abruptly as shown by the dashed line than the change shown by the dashed line at the time of low shift response,
A shift shock occurs. Therefore, conventionally, for example,
As described in JP-A-97327, a technique has been proposed in which the speed change response of a continuously variable transmission is reduced during deceleration during operation of a vehicle speed control device (constant speed traveling device).

[0005]

However, if the speed change response of the continuously variable transmission is unconditionally reduced during deceleration during operation of the vehicle speed control device (constant speed traveling device), the low vehicle speed The problem is that sufficient deceleration cannot be obtained only by reducing the engine output because the deceleration-promoting external force such as running resistance is also small during running on a vehicle, giving the driver a feeling of delay in vehicle deceleration due to downshift delay. Is generated.

According to the first aspect of the present invention, in view of the problem of the shift shock, it is only necessary to reduce the shift response of the continuously variable transmission at a high vehicle speed, and during traveling at a low vehicle speed. Based on the realization that a shift shock would not be a problem due to the inherently low vehicle speed due to a sudden downshift, and to reduce the above-mentioned problem relating to the reduction in vehicle speed control performance, deceleration during operation of the vehicle speed control device Based on the realization that it is better to increase the shift response of the continuously variable transmission even when the vehicle speed is low, the idea is embodied to achieve a vehicle speed that can satisfy all demands during deceleration during operation of the vehicle speed control device. It is an object of the present invention to propose a shift control device for a continuously variable transmission for a vehicle with a control device.

According to a second aspect of the present invention, there is provided a transmission control apparatus for a continuously variable transmission for a vehicle with a vehicle speed control apparatus, wherein the operation and effect of the first aspect are achieved at a low cost using a low-pass filter. The purpose is to propose.

According to a third aspect of the present invention, there is provided a vehicle speed control apparatus wherein the effects of the first aspect of the present invention are more reliably achieved while eliminating the influence of a shift response delay inherent in a continuously variable transmission. It is an object of the present invention to propose a shift control device for a continuously variable transmission for a vehicle with a gear.

According to a fourth aspect of the present invention, the speed ratio command value is not discontinuous according to the second or third aspect of the invention, and deterioration of the speed change characteristics due to a sudden change thereof can be avoided. An object of the present invention is to propose a shift control device for a continuously variable transmission for a vehicle with a vehicle speed control device.

[0010]

SUMMARY OF THE INVENTION To achieve these objects, a shift control device for a vehicle continuously variable transmission with a vehicle speed control device according to a first aspect of the present invention transmits an output from a prime mover to drive wheels via a continuously variable transmission. A vehicle having a vehicle speed control device for controlling the output of a prime mover and / or operating the speed ratio of a continuously variable transmission to maintain a set vehicle speed, wherein the vehicle speed control device is configured to operate during transmission. Set vehicle speed changing means capable of increasing or decreasing the vehicle speed is provided, and at least at the time of a vehicle deceleration request, the shift response of the continuously variable transmission is changed in accordance with the vehicle speed, and the shift response is made higher at low vehicle speeds than at high vehicle speeds. It is characterized by the following.

According to a second aspect of the present invention, there is provided a transmission control device for a continuously variable transmission for a vehicle with a vehicle speed control device according to the first aspect, wherein the transmission ratio command value of the continuously variable transmission is passed through a low-pass filter to contribute to shift control. The shift response is realized by setting the time constant of the low-pass filter to a small value including 0 at a low vehicle speed and a large value at a high vehicle speed.

According to a third aspect of the present invention, there is provided a shift control device for a continuously variable transmission for a vehicle with a vehicle speed control device according to the first aspect, wherein the filter having a built-in inverse system of a shift control response characteristic inherent to the continuously variable transmission is provided. The gear ratio control command value of the stepped transmission is used to contribute to shift control, and the time constant of the filter is changed so that the shift response of the continuously variable transmission is higher at low vehicle speeds than at high vehicle speeds. It is assumed that.

According to a fourth aspect of the present invention, there is provided a transmission control apparatus for a continuously variable transmission for a vehicle with a vehicle speed control apparatus according to the second or third aspect, wherein the time constant of the filter is continuously changed according to the vehicle speed. It is characterized by the following.

[0014]

The shift control device for a continuously variable transmission according to the first invention is set by controlling the output of a prime mover, operating the speed ratio of the continuously variable transmission, or performing both of them. While maintaining the vehicle speed, at least when there is a request for deceleration of the vehicle, the shift response of the continuously variable transmission is changed according to the vehicle speed, and this shift response is made higher at low vehicle speeds than at high vehicle speeds. Such an effect can be obtained.

That is, the shift of the continuously variable transmission in response to the deceleration request during the operation of the vehicle speed control device is a downshift. However, at low vehicle speed, the shift shock is a problem because the vehicle speed is originally low even with a sudden downshift. Therefore, as described above, even when the speed change response of the continuously variable transmission is increased at the time of the deceleration request during the operation of the vehicle speed control device, no problematic shift shock occurs. By increasing the shift response of the continuously variable transmission at the time of a deceleration request during the operation of the vehicle speed control device, the downshift is performed quickly, and the vehicle is decelerated by the downshift with high response. Thus, the above-described problem relating to the decrease in the vehicle speed control performance can be solved.

According to the first aspect of the present invention, the shift response of the continuously variable transmission is reduced if the vehicle speed is high even at the time of deceleration request during the operation of the same vehicle speed control device. As a result, it is possible to alleviate the shift shock which is a problem when a sudden downshift occurs due to a high vehicle speed. In addition, under high vehicle speeds, the deceleration-promoting external force such as running resistance is large, and the vehicle can be decelerated with a predetermined response even with a slow downshift. Will not occur.

In the second invention, the speed ratio command value of the continuously variable transmission is passed through a low-pass filter so as to contribute to speed change control, and the time constant of the low-pass filter is set to a small value including 0 at a low vehicle speed. At a high vehicle speed, the shift response in the first invention is realized by setting the value to a large value, so that the operation and effect of the first invention can be achieved by an inexpensive method using a low-pass filter.

According to a third aspect of the present invention, a filter having a built-in inverse system of a shift control response characteristic inherent to a continuously variable transmission is used to contribute to shift control by transmitting a speed ratio command value of the continuously variable transmission, and a time constant of the filter is provided. At low vehicle speeds so that the shift response of the continuously variable transmission is higher than at high vehicle speeds, the gear ratio command value after passing through the above filter allows for a shift response delay inherent in the continuously variable transmission. It is a value that can achieve the operation and effect of the first invention, and the operation and effect of the first invention can be more reliably achieved while eliminating the influence of the shift response delay inherent in the continuously variable transmission. .

In the fourth invention, the second invention or the third invention
Since the time constant of the filter in the present invention is continuously changed according to the vehicle speed, the speed ratio command value is not discontinuous even in the second or third invention, and deterioration of the speed change characteristics due to the sudden change is avoided. Can be.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a functional block diagram showing a system configuration of a vehicle speed control device (constant speed traveling device: ASCD) including a shift control device of a continuously variable transmission according to an embodiment of the present invention. This vehicle speed control device mainly includes a vehicle speed control unit 500 enclosed by a broken line that enables a microcomputer, and includes a vehicle speed sensor 10, an ASCD that is a control input component on the left side of the drawing.
Set switch 20, coast (deceleration) switch 30,
The accelerator (acceleration) switch 40 connects the engine rotation sensor 80 and the accelerator pedal sensor 90,
The control output parts on the right side of the figure are constituted by connecting the brake actuator 50, the throttle controller 575 of the throttle actuator 60, and the controller of the continuously variable transmission 70.

The vehicle speed control device shown in FIG. 1 is turned on as a whole when a system switch (not shown) is turned on, and is in a standby state.
When the driver turns on the CD set switch 20, control is started. The vehicle speed control unit 500 will be described below. The vehicle speed command value determination unit 510 repeatedly performs the vehicle speed command value (set vehicle speed) V _COM to be maintained by the vehicle speed control device at every elapse (t) of a predetermined control cycle of 10 ms. (T) is calculated as described below.

The vehicle speed command maximum value setting unit 520 includes an ASCD
Vehicle speed sensor 1 when set switch 20 is pressed
The vehicle speed _VA (t), which is the detected value of 0, is set to the vehicle speed command maximum value V
Set as _{SM AX} (target vehicle speed). After the vehicle speed command maximum value V _SMAX is set by the ASCD set switch 20 as described above, the vehicle speed command maximum value setting unit 520 outputs the vehicle speed command maximum value V every time the coast switch 30 is pressed once by the driver. _{Reset SMAX} to a lower value by 5 km / h. That is, if the coast switch 30 is pressed n times, n × 5 km / h [if the switch is kept pressed, the pressing time is assumed to be t, for example, t (s) / 1 (s) × 5
(Km / h)].

After the vehicle speed command maximum value _VSMAX is set by the ASCD set switch 20 as described above, the vehicle speed command maximum value setting section 520 sets the vehicle speed command every time the accelerator switch 40 is pressed once by the driver. _{Reset the} command maximum value _VSMAX to a higher value by 5 km / h.
That is, when the accelerator switch 40 is pressed n times, n
× 5 km / h [If pressing is continued, if the pressing time is t, for example, t (s) / 1 (s) × 5 (km / h)]
And reset it to a higher value.

As will be described later in detail with respect to the vehicle speed command value determining unit 510, when acceleration is requested by operation of the accelerator switch 40 and the target vehicle speed increases, the vehicle speed V _A (t) is increased to the current vehicle speed V _A (t). Vehicle speed command value V _COM (t) is calculated by adding vehicle speed command value change amount ΔV _COM (t) determined by command value change amount determining section 590.
Further, when the target vehicle speed is reduced due to a request for deceleration by the operation of the coast switch 30, the current vehicle speed _VA (t)
From calculates a command vehicle speed _{V C} OM (t) by subtracting the vehicle speed command value change amount determined by the vehicle speed command value variation determining section 590 △ _{V COM} (t).

The vehicle speed command value change amount determining section 590 determines the vehicle speed command value change amount に よ り based on the absolute value of the vehicle speed deviation between the host vehicle speed _VA (t) and the vehicle speed command maximum value V _{SM AX} by using a map shown in FIG. Search for V _COM (t). The map shown in FIG. 3 shows that when the absolute value of the vehicle speed deviation is within a certain range (range B in FIG. 3), the larger the absolute value of the vehicle speed deviation is, the larger the absolute value of the vehicle speed deviation becomes. ΔV _COM (t) is increased to accelerate or decelerate as quickly as possible. The smaller the absolute value of the vehicle speed deviation, the smaller the vehicle speed command value change amount within a range where the sense of acceleration is not impaired.
_COM (t) is reduced, and the vehicle speed command maximum value V _{S MAX}
Is determined not to overshoot.

In a range where the absolute value of the vehicle speed deviation is large (range A in FIG. 3), the vehicle speed command value change amount ΔV _COM (t) is set so as to be a constant acceleration (for example, 0.06 G) not exceeding the acceleration limit value α. ) Is a constant value corresponding thereto, and a range in which the absolute value of the vehicle speed deviation is small (a range C in FIG. 3).
In this case, the vehicle speed command value change amount ΔV is set so as to be a constant acceleration (for example, 0.03 G) that does not fall below the acceleration limit value.
_COM (t) is set to a constant value corresponding to this.

The vehicle speed command value determining section 510 determines the vehicle speed V
_A (t), the vehicle speed command value change amount ΔV _COM (t) and the vehicle speed command maximum value V _SMAX are input, and based on these, the vehicle speed command value V _COM (t) is calculated as follows. (1) When the maximum vehicle speed command value V _SMAX is larger than the own vehicle speed V _A (t), that is, when there is an acceleration request by operating the accelerator switch 40, the vehicle speed command value V _COM (t) is obtained by the following equation. . V _COM (t) = min [V _SMAX , _VA (t) + △
V _COM (t)] That is, the vehicle speed command maximum value V _SMAX and _VA (t) + △
The smaller one of V _COM (t) is selected and set as a vehicle speed command value V _COM (t). (2) When the vehicle speed command maximum value V _SMAX is equal to the own vehicle speed _VA (t), that is, when the constant vehicle speed is maintained,
The vehicle speed command value V _COM (t) is obtained by the following equation. V _COM (t) = V _SMAX That is, the vehicle speed command maximum value V _{SMAX is changed} to the vehicle speed command value V
_COM (t). (3) When the vehicle speed command maximum value V _SMAX is smaller than the _host vehicle speed V _A (t), that is, when there is a deceleration request by operating the coast switch 30, the vehicle speed command value V is calculated by the following equation.
_COM (t) is obtained. V _COM (t) = max [V _SMAX , _VA (t) − △
V _COM (t)] That is, the vehicle speed command maximum value V _SMAX and _VA (t) − △
The larger one of V _COM (t) is selected and set as a vehicle speed command value V _COM (t). As described above, the vehicle speed command value V
_COM (t) is determined, and the braking / driving force of the wheels via the throttle actuator 60 or the brake actuator 50 of the engine (motor) so that the own vehicle speed V _A (t) follows the vehicle speed command value V _COM (t). And the speed of the continuously variable transmission 70 is controlled via its controller as necessary. In the present embodiment, an example in which the brake actuator 50 is used has been described. However, the brake force may be obtained only by the engine braking force by downshifting the continuously variable transmission without providing the brake actuator 50. .

The drive torque command value calculation section 530 receives the vehicle speed command value V _COM (t) and the own vehicle speed V _A (t),
Based on these, the driving torque command value d is calculated as follows.
Calculate _FC (t). FIG. 4 is a functional block diagram illustrating an example of the configuration of the drive torque command value calculation unit 530. The vehicle speed command value V _COM (t) is input and the own vehicle speed V _A (t) is input.
Is the output, the transfer characteristic Gv (s) can be expressed by the following equation. Gv (s) = 1 / ( Tv · S + 1) · e (-Lv · S) However, _{T v} is a first-order lag time constant, _{L v} is the dead time due to a delay of the power train system.

In the vehicle model to be controlled, the driving torque command value d _FC (t) is used as an operation amount, and the own vehicle speed _{VA is used.}
By modeling (t) as a control amount, the behavior of the vehicle power train can be represented by a simple linear model represented by the following equation. _{V A (t) = 1 /} (m v · Rt · S) e (-Lv · S)
· _D FC (t) However, Rt is the effective radius of rotation of the tire, _{m v} is the vehicle mass. As described above, a vehicle model that receives the drive torque command value d _FC (t) and outputs the own vehicle speed _VA (t) has a 1 / s form, and thus has an integral characteristic.

[0030] Incidentally, the dead time due to the delay L _v powertrain system to the characteristics of the controlled object is also included, also for non-linear characteristics that change the value of the dead time L _v, such later approximation by an actuator and engine used By using the disturbance estimator based on the zeroing method, a vehicle model that receives the drive torque command value d _FC (t) and outputs the own vehicle speed _VA (t) can be represented by the same equation as above.

Here, when the vehicle speed command value V _COM (t) is input and the own vehicle speed _VA (t) is output, the response characteristic of the control object is determined by a predetermined primary delay _Tv and a dead time _Lv. When matching the transfer characteristics G _v (s) having the elements, C _l (s), C ₂ (s) and C ₂ (s) as shown in FIG.
₃ (s), it can be determined as follows.
Here, C ₁ (s) and C ₂ (s) indicate disturbance estimators based on the approximate zeroing method, and are compensators that work to suppress the influence of disturbances and modeling errors, and C ₃ (s) is model matching. 3 shows a compensator based on the technique. Compensator ^{_{C l (s) = e (}} -Lv · S) / (T H · S +
1) the compensator _{C 2 (s) = (m} v · Rt · S) / (T H · S +
1) In this case, the estimated disturbance value _d v (t) _{is, d v (t) = C} 2 (s) · V A (t) -C l (s) · d
_FC (t).

If the reference model G _v (s) is a first-order low-pass filter with a time constant T _v ignoring the dead time of the control object, the compensator C ₃ (s) has the following constant. With the compensator C ₁ (s), C ₂ (s), and C ₃ (s) that is equal to or greater than the compensator C ₃ (s) = m _v · Rt / T _v , the drive torque command value d _FC (t) becomes It is calculated by the formula. d _FC (t) = C ₃ (s) · ΔV _COM (t) −V
_A (t)｝-｛C ₂ (s) · V _A (t) -C ₁ (s) ·
d _FC (t)｝

By controlling the drive torque as follows based on the drive torque command value d _FC (t) calculated as described above, the vehicle speed _VA (t) is changed to the vehicle speed command value V
_COM (t). That is, a throttle opening command value that matches the actual driving torque d _FA (t) with the driving torque command value d _FC (t) is calculated based on a previously measured engine non-linear steady-state characteristic map as shown in FIG. If there is a deceleration request that is not sufficient with the negative driving torque of the engine, the shortage is distributed so as to be supplemented by the downshift of the continuously variable transmission or the operation of the brake.
As described above, by controlling the throttle opening, the speed ratio of the continuously variable transmission, and the brake operation, the engine non-linear steady-state characteristics can be linearized.

The actual speed ratio calculating section 550 of FIG. 1 calculates the engine speed N detected by the engine speed sensor 80.
_E (t) and the own vehicle speed V detected by the sensor 10
_A (t), the continuously variable transmission 70 according to the following equation:
Of the actual speed ratio RATIO (t) is calculated. _{RATIO (t) = N E (} t) / _[V A (t) · Gf ·
2π · Rt] where Gf is the final drive gear ratio, and Rt
Is the tire effective radius. The engine torque command value calculation unit 560 calculates the drive torque command value d _FC (t) and the actual gear ratio R
From ATIO (t), an engine torque command value TE _COM (t) is calculated according to the following equation. TE _COM (t) = d _FC (t) / [Gf · RATIO
(T)]

The target throttle opening calculating section 570 calculates the engine torque command value TE _COM (t) and the engine speed N
_{Based on E} (t), a target throttle idleness TVO _COM is calculated from an engine full performance map as shown in FIG. 6, and this is output to the throttle controller 575.
The throttle controller 575 receives the target throttle opening TVO _COM (t) and determines a drive signal command value Duty (t) to the throttle actuator 60 based on the target throttle opening TVO _COM (t) as follows.

The throttle controller 575 is as shown in the block diagram of each function shown in FIG. 7, and the control model of the throttle actuator 60 to be controlled includes a pre-compensation drive signal (duty ratio) command value Duty-R (t). By modeling the manipulated variable and the throttle opening equivalent value TVO (t) as a control variable, it can be represented by a simple linear model represented by the following equation. TVO (t) = (ka / s) · e− ^{La · s} · Duty
R (t) where ka is an integral gain (opening / closing speed at Duty 00%), and La is a dead time. As described above, the control model that receives the pre-compensation drive signal (duty ratio) command value Duty_R (t) and outputs the throttle opening equivalent value TVO (t) has a 1 / s form, and thus has an integral characteristic. You can see that.

The characteristic of the control object has a non-linear characteristic in which the dead time La changes depending on the actuator used. However, by using a disturbance estimator based on the approximate zeroing method described later, the drive signal (duty ratio) command value before compensation is obtained. A control model in which Duty_R (t) is input and the throttle opening equivalent value TVO (t) is output can be expressed by the same equation as the above equation.

Here, the response characteristic of the control target when the pre-compensation drive signal (duty ratio) command value Duty_R (t) is input and the throttle opening equivalent value TVO (t) is output is a predetermined primary characteristic. When matched with the characteristics of the transfer characteristic Ga (s) having the elements of the delay Ta and the dead time La, C ₄ (s), C ₅ (s) and C
_{6 Using} (s), it can be determined as follows.
Here, C ₄ (s) and C ₅ (s) indicate disturbance estimators based on the approximate zeroing method, which are compensators that work to suppress the influence of disturbances and modeling errors, and C ₆ (s) is model matching. 3 shows a compensator based on the technique. Compensator C ₄ (s) = e− ^{La · s} / (Ta · S + 1) Compensator C ₅ (s) = S / {ka · (Ta · S + 1)}

At this time, the estimated disturbance value d _va (t) is given by: d _va (t) = C ₅ (s) · TVO (t) −C ₄ (s)
Duty_R (t) When the reference model is a first-order low-pass filter with a time constant Tb, ignoring the dead time of the control object,
The compensator C ₆ (S) has the following constants. Compensator C ₆ (S) = (ka · Tb) The above-described compensator of C ₄ (s), C ₅ (s), and C ₆ (s) allows the pre-compensation drive signal (duty ratio) command value Duty_
R (t) is calculated by the following equation. Duty_R (t) = C ₆ (s) · ｛TVO
_COM (t) -TVO (t)｝-｛C ₅ (s) · TVO
(T) −C ₄ (s) · Duty_R (t))｝

When a negative pressure type actuator is used as the throttle actuator 60 instead of the above, compensation is likely to be caused by non-linear factors such as friction at the time of ON / OFF of a vacuum motor for generating a negative pressure and at opening / closing of a vent valve. Previous drive signal (duty ratio) command value Duty_R (t)
In response to this, a throttle opening vacuum (VAC) / throttle closing vent (VENT) drive signal Duty (t), which has been subjected to nonlinear compensation using a map as shown in FIG. Here, from the pre-compensation drive signal (duty ratio) command value Duty_R (t) to V
The non-linear compensation map for calculating the AC / VENT drive signal Duty (t) has a duty_R (t) as shown in FIG.
If ≧ 0, it is like a VAC (valve) drive signal, and if Duty_R (t) <0, it is like a VENT (valve) drive signal.

It should be noted that the negative pressure type actuator operates using a negative pressure as a power source, and the negative pressure therefor may be generated by driving a vacuum motor or may be a negative pressure of an intake pipe. Note that the negative pressure actuator is driven so that the throttle is opened at the time of vacuum (VAC) and the throttle is closed at the time of vent (VENT).

The brake pressure command value calculation section 630 of FIG.
Based on the engine rotational speed _N E (t), 'seek, the engine brake torque _{TE C OM'} throttle opening (TVO) is fully closed in the engine brake torque _{TE COM} from the engine performance map shown in FIG. 6 and the engine A brake pressure command value REF _PBRK (t) is calculated from the torque command value TE _COM (t) according to the following equation, and is output to the brake actuator 50. REF _PBRK (t) = (TE _COM −TE _COM ')
· Gm · Gf / {4 · (2 · AB · RB · µB)] where Gm is the gear ratio of the continuously variable transmission, AB is the wheel cylinder force (cylinder pressure x area), RB is the effective radius of the disks rotor, and µB is Pad friction coefficient.

The gear ratio command value calculating section 540 in FIG.
FIG. 2 also shows a shift control unit in the transmission 70.
The speed change of the continuously variable transmission 70 shown in FIG.
First, the control unit will be described. Shift control for continuously variable transmission 70
The shift map 73 in the control unit is as shown in FIG.
So, based on this map,_A(T) and
Accelerator pedal depression detected by cell pedal sensor 90
The transmission input rotation speed command value to be targeted from the displacement APO
N_{IN COM}Ask for. The rotation speed limiting unit 74
Rotational speed command value N obtained as follows_{IN COM}Against
To limit engine speed to protect the engine (for example,
If N_{IN COM DEC}≦ 6400 [rpm])
The transmission input rotation speed command value N after the restriction_IN
COMCVTIs output to the gear ratio command value calculation unit 75.

The gear ratio command value calculation unit 75 calculates the vehicle speed V
_A (t) and transmission input rotational speed command value N _IN after restriction
_COMMCVT and the speed ratio command value DRATI during normal running while the vehicle speed is not controlled by the following equation.
Obtain O _CVT (t). DRATIO _CVT (t) = N _{IN COMCVT}・ 2
π · Rt / (60 · V _A (t) · Gf)

The changeover switch 71 is normally set to a changeover position indicated by a solid line, and the speed ratio command value DRATIO during normal running calculated in the continuously variable transmission 70 as described above.
Select and output _CVT (t). However, the AS in FIG.
When the CD set switch 20 is pressed to switch from the normal running to the constant speed running by the vehicle speed control, the changeover switch 71 is changed from the solid line position to the broken line position by the setting of the vehicle speed control flag set in the vehicle speed command maximum value setting unit 520. During the constant speed traveling, the speed ratio command value DRATIO _LPF (t) at the time of constant speed traveling obtained by the speed ratio command value calculating unit 540 in the vehicle speed control unit 500 is output as described later.

The filter unit 72 receives the above-mentioned vehicle speed control flag from the vehicle speed command maximum value setting unit 520 and the accelerator pedal depression amount APO, and switches the filter time constant according to the running state. Switch 71 to the filter unit 72 having the specified time constant
DRTO after passing the gear ratio command value from
(T) is sent to the shift control servo unit 76 to control the shift of the continuously variable transmission as is well known.

The transmission characteristic of the gear ratio control when the gear ratio command value DRTO (t) is input to the gear shift control servo unit 76 and the actual gear ratio is output is as follows: It can be represented by a transfer characteristic Gr (s). Gr (s) = 1 / ( _TCVT · S + 1) where _TCVT is a time constant (variable value within a predetermined range) that determines a response characteristic of the continuously variable transmission 70 during shifting, and this shift control time constant _TCVT Is switched in accordance with the traveling state, it is possible to provide a shift characteristic suitable for the driver's feeling.

Next, the gear ratio command value calculation section 540 in the vehicle speed control section 500 including the gist of the present invention will be described in detail with reference to FIG. This gear ratio command value calculation unit 540
Is the driving torque command value d _FC (t), the own vehicle speed V
_A (t) and the accelerator pedal depression amount APO are input, and the gear ratio command value DRA at the time of constant speed traveling is input as follows.
The TIO _LPF (t) is calculated and output to the changeover switch 71.

First, the throttle opening degree estimation map 541,
Drive by shift map 544 and rotation speed limiter 545
Transmission input rotation speed command value N_{IN COM ACC}Performance
The arithmetic processing will be described. The throttle opening estimation map 541 is
Own vehicle speed V_A(T) and drive torque command value d_{F C}(T) and
The driving throttle shown in FIG.
Throttle opening estimated value TVO based on opening estimation map
_ESTIIs calculated. The shift map 544 is
Estimated torque opening TVO_ESTIAnd own vehicle speed V_A(T)
9 based on the shift map shown in FIG.
Command value N_{IN COM ACC}Ask for.

The rotation speed limiter 545 is provided for the drive speed change.
Machine input rotation speed command value N_{IN COM ACC}Against
Limit processing for protecting the gin (for example, N_{IN
COM ACC}≦ 6400 [rpm])
Drive transmission input rotation speed command value N after rotation speed processing_{IN
COM ACC}Is output to the changeover switch 547.

Next, calculation of the input value of the rotational speed of the braking transmission
Brake change by the map 542 and the rotation speed limiter 546
Speed input speed command value N_{IN COM DEC}Arithmetic processing of
Will be explained. Input speed command value calculation map for braking transmission
542 is the vehicle speed V_A(T) and drive torque command value d
_FCFrom (t), the engine when the throttle is fully closed
The driving mask shown in FIG. 10 was created based on the characteristics.
Input speed command value calculation map for braking transmission separate from top
Input speed command value N for braking transmission based on_{IN COM
D EC}Search for. The rotation speed limiter 546 is used for this braking.
Transmission input speed command value N_{IN COM DEC}Against
Upper limit rotation speed restriction processing (for example, N_{IN COM DEC}
≤ 5000 [rpm]) and the control after the upper limit rotation speed processing.
Driving transmission input rotation speed command value N_{I N COM DEC}To
Calculated, and this braking transmission input rotation speed command value N_{IN
CO M DEC}Is output to the changeover switch 547.

Next, the gear ratio command value DRATI by the changeover switch 547 and the gear ratio command value calculation unit 548.
The calculation processing of O (t) will be described. Changeover switch 54
When the sign is positive (driving) in accordance with the sign of the drive torque command value d _FC (t), the drive transmission input rotation speed command value N _IN after the upper limit processing is set to the solid line position. _{COM
When ACC} is selected and the sign of the driving torque command value d _FC (t) is negative (braking), the changeover switch 547 is set to the position indicated by the broken line, and the braking transmission input rotation speed command value N _IN after the upper limit processing is performed. _{COM DEC} is selected, and the final transmission input rotation speed command value N _{IN COM} .

The gear ratio command value calculation section 548 calculates the own vehicle speed _VA.
(T) and the final transmission input rotational speed command value N _{IN
From COM} , a gear ratio command value DRATIO (t) is calculated by the following equation. DRATIO (t) = N _{IN COM}・ 2π ・ Rt /
[60 VA (t) Gf]

Finally, a description will be given of the filtering process of the gear ratio command value DRATIO (t) by the filter unit 549.
The filter unit 549 controls the vehicle speed V _A (t) in FIG.
As shown in FIG. 1, a low-pass filter having a time constant T _nc that continuously changes between 0 and 0.35 seconds is filtered through the above-described speed ratio command value DRATIO (t) to change the speed at the time of constant speed running. Ratio command value DRATIO
_LPF (t) DRATIO _LPF (t) = DRATIO (t) / (T
_nc · S + 1) is obtained and input to the changeover switch 71 to contribute to the above-described shift control.

Incidentally, the time constant T _{nc of} the filter unit (low-pass filter) 549 changes as shown in FIG. 11 according to the vehicle speed V _A (t), and becomes 0 sec at a low vehicle speed.
As the vehicle speed V _A (t) increases, the speed continuously increases from 0 sec to 0.35 sec. Therefore, in a low vehicle speed range, the state becomes the same as that without the low-pass filter 649, and the shift response of the continuously variable transmission becomes faster. As the vehicle speed increases, the shift response of the continuously variable transmission decreases. Therefore, the vehicle speed control unit 500 operates to maintain the set vehicle speed by the engine output control via the throttle actuator 60, the wheel braking / driving force control by braking via the brake actuator 50, and the shift control of the continuously variable transmission 70. During this period, the shift response of the continuously variable transmission is made higher at low vehicle speeds than at high vehicle speeds, and the following operational effects can be obtained.

That is, the shift of the continuously variable transmission 70 in response to the deceleration request during the operation of the vehicle speed control device is a downshift, but at low vehicle speed, the vehicle speed is inherently low even by a sudden downshift, so that the shift shock is performed. As described above, even if the speed change response of the continuously variable transmission is increased at the time of a deceleration request during the operation of the vehicle speed control device, no problematic shift shock occurs. By increasing the shift response of the continuously variable transmission at the time of a deceleration request during the operation of the vehicle speed control device, the downshift is performed quickly, and the vehicle is decelerated by the downshift with high response. Thus, the above-described problem relating to the decrease in the vehicle speed control performance can be solved.

Even when a deceleration request is made during the operation of the same vehicle speed control device, the shift response of the continuously variable transmission is reduced if the vehicle speed is high, so that the downshift is performed slowly at a high vehicle speed. It is possible to alleviate a shift shock which is a problem when a sudden downshift occurs due to the vehicle speed, and also to prevent generation of noise due to a sudden increase in the input speed of the transmission. In addition, under high vehicle speeds, the deceleration-promoting external force such as running resistance is large, and the vehicle can be decelerated with a predetermined response even with a slow downshift. Will not occur.

Further, the speed ratio command value DRA of the continuously variable transmission
After passing the TIO (t) through the low-pass filter 549, the low-pass filter 549 is used.
The time constant T _nc is set to a small value including 0 at a low vehicle speed and a large value at a high vehicle speed to realize the above-mentioned shift response. Therefore, the above-described operation and effect are realized by an inexpensive method using a low-pass filter 549. Can be achieved.

In the above description, not only when deceleration is requested during operation of the vehicle speed control device but also when deceleration is not requested,
The time constant T _nc (shift response of the continuously variable transmission) of the low-pass filter 549 is similarly changed in accordance with the vehicle speed. Therefore, in order to simplify the control, the time constant T _nc of the low-pass filter 549 is changed in a case other than the deceleration request in the same manner as in the case of the deceleration request. However, when it is necessary to control the time constant T _nc of the low-pass filter 549 differently from when the deceleration request is made, as shown in FIG. 2, the filter unit 549 supplies the drive torque command value d _FC (t) to the filter unit 549 as shown in FIG. A code is input, and it is determined whether the vehicle is in a deceleration request or other than a deceleration request during operation of the vehicle speed control device. According to the determination result, the time constant of the low-pass filter 549 is different from that in the deceleration request except in the deceleration request. T _nc may be controlled.

Further, instead of using a low-pass filter as described above, the filter section 549 previously has an inverse system ( _TCVT · S +) of the shift control response characteristic inherent to the continuously variable transmission.
1), and a filter having a time constant T _nc that continuously changes between 0.15 and 0.5 seconds as shown in FIG. 12 according to the own vehicle speed V _A (t). In this case, the above-described gear ratio command value DRAT
Gear ratio command value DRATIO at the time of constant speed traveling obtained by filtering through IO (t)
_LPF (t) is DRATIO _LPF (t) = DRATIO (t) · (T
_CVT · S + 1) / (T _nc · S + 1)

[0061] In this embodiment, the continuously variable transmission to specific shift control response characteristic inverse system _{(T C VT · S + 1} ) to the filter unit 549 with a built-in continuously variable transmission gear ratio command value DRatio (t ), And to change the time constant T _nc of the filter 549 so that the shift response of the continuously variable transmission is higher at low vehicle speeds than at high vehicle speeds as shown in FIG. 549
Ratio command value DRAT during constant speed running after passing through
IO _LPF (t) is a value anticipating the shift response delay inherent in the continuously variable transmission and a value capable of achieving the same operation and effect as in the above-described embodiment. The above effects can be achieved more reliably while eliminating the effects of the response delay.

In any of the embodiments, the time constant T _nc of the filter section 549 is continuously changed according to the vehicle speed V _A (t) as shown in FIGS. Ratio command value DRATIO
_LPF (t) does not become discontinuous, and deterioration of the shift characteristic due to the sudden change can be avoided.

When the vehicle speed control unit 500 and the shift control unit in the continuously variable transmission 70 shown in the functional block diagram in FIG. 2 are constituted by microcomputers, the control programs are the same as those shown in FIGS. Become. FIG.
Is the gear ratio command value DR when the vehicle speed control unit 500 is traveling at a constant speed.
In the control program for obtaining the ATIO _LPF (t), step S541 is executed in the throttle opening estimation map 54.
1 is performed, step S544 performs a process in the shift map 544, and step S542 performs a process in the brake transmission input rotation speed command value calculation map 542. Steps S547a, 547b, 547
c performs the processing in the changeover switch 547, step S548 performs the processing in the gear ratio command value calculation unit 548, and step S549 performs the processing in the filter unit 549.

FIG. 14 is a flowchart showing step S54 in FIG.
9 shows the processing in step S549a in detail.
Find the filter time constant _{T nc} based on FIG. 11 from the vehicle speed _V A (t) in the next step speed change ratio command value to the low pass filter of the time constant at S549b DRATI
O (t) is filtered and the speed ratio command value DRATIO _LPF (t) at constant speed traveling DRATIO _LPF (t) = DRATIO (t) / (T
_nc · S + 1).

FIG. 15 shows that the speed change control unit of the continuously variable transmission 70 shown in FIG. 2 has a final speed ratio command value DRTO (t).
In step S75, the processing in the shift map 73 and the gear ratio command value calculating unit 75 is performed, and steps S71a, S71b, and S71c perform the processing in the changeover switch 71, and step S7 is performed.
2 obtains the final gear ratio command value DRTO (t) by performing processing in the filter section 72, and performs processing in the gear shift control servo 76 in step S76.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating an entire configuration of a vehicle speed control device including a shift control device of a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a functional block diagram showing details of a gear ratio command value calculation unit 540 and a gear change control unit in the continuously variable transmission 70 in FIG.

FIG. 3 is a vehicle speed _VA (t) and a vehicle speed command maximum value V;
FIG. 9 is a change characteristic diagram showing a relationship between an absolute value of a vehicle speed deviation from _SMAX and a vehicle speed command value change amount ΔV _COM (t).

4 is a driving torque command value calculation unit 530 in FIG.
FIG. 3 is a block diagram showing the configuration of FIG.

FIG. 5 is a diagram showing an example of an engine non-linear steady-state characteristic map.

FIG. 6 is a diagram showing an example of an entire engine performance map.

FIG. 7 shows a throttle controller 575 in FIG.
FIG. 3 is a block diagram showing the configuration of FIG.

FIG. 8 shows a throttle actuator 60 shown in FIG.
FIG. 7 is a characteristic diagram used for obtaining a vacuum (VAC) / vent (VENT) drive signal Duty (t).

FIG. 9 is a shift map diagram illustrating shift characteristics of a continuously variable transmission.

FIG. 10 is a diagram showing an example of a throttle opening degree estimation map.

FIG. 11 is a diagram showing a change characteristic of a time constant of a low-pass filter determined for controlling a shift response.

FIG. 12 is a diagram showing a change characteristic of a time constant of another type of filter determined to control a shift response.

FIG. 13 is a flowchart showing a control program executed when a vehicle speed control unit obtains a gear ratio command value during constant speed traveling.

FIG. 14 is a flowchart showing a control program related to a filter process of a gear ratio command value in the same program.

FIG. 15 is a flowchart illustrating a control program executed when a shift control unit in the continuously variable transmission obtains a final gear ratio command value.

FIG. 16 is a shift operation time chart used to explain how a shift shock occurs due to a difference in shift response of the continuously variable transmission.

[Explanation of symbols]

 10 Vehicle speed sensor 20 ASCD set switch 30 Coast switch 40 Accelerate switch 50 Brake actuator 60 Throttle actuator 70 Continuously variable transmission 71 Changeover switch 72 Low-pass filter unit 73 Shift map 74 Rotation limit unit 75 Gear ratio command value calculation unit 76 Shift control servo Unit 80 Engine rotation sensor 90 Accelerator pedal sensor 500 Vehicle speed control unit 510 Vehicle speed command value determination unit 520 Vehicle speed command maximum value setting unit 530 Drive torque command value calculation unit 540 Gear ratio command value calculation unit 541 Throttle opening estimation map 542 Braking shift Engine input speed command value calculation map 545 Speed limiter 546 Speed limiter 547 Changeover switch 548 Gear ratio command value calculator 549 Filter unit 560 Engine torque command value calculator 570 Target throttle opening calculator 575 Throttle controller 550 Actual Gear ratio calculator 590 Vehicle speed command value change amount determiner 630 Brake pressure command value calculator

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 29/00 F02D 29/00 H 29/02 301 29/02 301C F16H 9/00 F16H 9/00 J // F16H 59 : 24 59:24 59:42 59:42 59:44 59:44 63:06 63:06 F term (reference) 3D041 AA31 AA53 AA66 AA76 AB01 AC01 AC19 AC26 AD02 AD04 AD31 AD39 AD51 AE04 AE31 AE40 AE41 3D044 AA04 AA42 AA45 AB01 AC05 AC15 AC24 AC26 AC39 AD04 AD16 AD21 AE15 AE19 AE27 3G093 AA06 BA03 BA15 BA23 CB07 DA01 DA06 DB05 DB11 EA09 EB03 EB04 EC02 EC04 FA08 FA10 FA12 3J552 MA06 NA01 NB01 PA02 PA20 PA33 PA39 RB06 TB03 TB03 RB06 TB07 RB06 TB03 RB07 UA09 VA32Z VA74Z VB01W VB04Z VC01Z VC03Z VD02Z VD11Z VD16Z VD17Z VE03Z

Claims (4)

[Claims] 1. A vehicle for transmitting an output from a prime mover to drive wheels via a continuously variable transmission, wherein the vehicle speed is controlled by controlling the output of the prime mover and / or operating the speed ratio of the continuously variable transmission. In a vehicle equipped with a vehicle speed control device to be maintained, a setting vehicle speed changing means capable of increasing or decreasing a set vehicle speed during operation of the vehicle speed control device is provided, and at least at the time of a vehicle deceleration request, a shift response of the continuously variable transmission changes according to the vehicle speed. A shift control device for a continuously variable transmission for a vehicle with a vehicle speed control device, wherein the shift response is made higher at a low vehicle speed than at a high vehicle speed. 2. The low-pass filter according to claim 1, wherein the transmission ratio command value of the continuously variable transmission is passed through a low-pass filter to contribute to speed change control, and the time constant of the low-pass filter is set to a small value including 0 at a low vehicle speed. A shift control device for a continuously variable transmission for a vehicle with a vehicle speed control device, wherein the shift response is realized by setting a large value at a high vehicle speed. 3. The filter according to claim 1, wherein a filter having a built-in inverse system of a shift control response characteristic inherent to the continuously variable transmission is used to contribute to shift control through a speed ratio command value of the continuously variable transmission. Wherein the time constant of the stepless transmission is changed so that the shift response of the continuously variable transmission becomes higher at low vehicle speeds than at high vehicle speed. 4. The shift control device for a vehicle continuously variable transmission with a vehicle speed control device according to claim 2, wherein the time constant of the filter is continuously changed according to the vehicle speed.