JP2580788B2 - Speed ratio control device for continuously variable transmission for vehicles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a speed ratio control device for a continuously variable transmission for a vehicle.

2. Description of the Related Art There is known a vehicle including a continuously variable transmission that continuously changes the rotation of an engine and transmits the rotation to drive wheels. In such a vehicle, for example, as described in JP-A-59-144850, the target input shaft rotation speed determined based on the throttle valve opening and the vehicle speed of the vehicle and the input of the continuously variable transmission are determined. The speed ratio is controlled so that the shaft rotation speed matches. Thus, the engine is operated along the optimum curve, and a high fuel efficiency is obtained. And
An anti-lock brake device for automatically adjusting a brake fluid pressure in a vehicle having a continuously variable transmission as described above so as to maintain a slip condition in a vehicle theory within a predetermined range in relation to a braking operation of the vehicle. May be provided. However, in such a case, it may be difficult to obtain a sufficient antilock operation when braking the vehicle. That is, in the speed ratio control of the continuously variable transmission, a vehicle speed (hereinafter, referred to as a drive wheel speed) is detected from a rotation speed of a member that rotates together with a drive wheel of the vehicle, and the speed ratio is adjusted based on at least the drive wheel speed. However, when the speed of the driving wheel is rapidly reduced by the braking operation of the vehicle, the speed ratio is rapidly changed to the maximum deceleration side, and an engine braking effect is applied to the driving wheel. For this reason, even when the braking force is reduced by the operation of the anti-lock brake device during the brake operation of the vehicle, the driving theoretical vehicle speed does not return to the vehicle body speed, and the anti-lock effect may be hindered.

In contrast, Japanese Patent Application No. 1-5676 filed earlier by the applicant of the present invention.
As described in No. 7, during the period when the anti-lock brake device (so-called ABS device) is operating, the low friction road surface is used to set the speed ratio used so far to the value on the speed increasing side. There is proposed a speed ratio control device for switching to the relation of. With such a device, when braking on a frozen road or the like where the road surface friction coefficient is significantly low, the anti-lock brake is provided by the engine braking effect caused by the speed ratio being rapidly changed to the deceleration side. There is a feature that the action is prevented from being inhibited.

Problems to be Solved by the Invention Incidentally, the road surface friction coefficient during braking of the vehicle may change, for example, from a frozen road surface to a snow-covered road surface. In such a case, as described above, when the speed ratio is controlled to the speed increasing side based on the relationship for the low friction road surface,
Since the vehicle stops before the speed ratio of the continuously variable transmission returns to the maximum deceleration side, the driving force is insufficient at the time of restart of the vehicle, and it may be difficult to restart.

The present invention has been made in view of the above circumstances, and the object thereof is that even when the road surface friction coefficient changes during the operation of the antilock brake of the vehicle,
When the vehicle stops, the speed ratio of the continuously variable transmission is returned to the maximum deceleration side, and a speed ratio control device for a continuously variable transmission for a vehicle is provided so that a sufficient driving force can be obtained when the vehicle restarts. To provide.

Means for Solving the Problems The gist of the present invention for achieving the above object is to provide a continuously variable transmission for continuously changing the rotation of an engine and transmitting the rotation to drive wheels, and a braking operation for a vehicle. In relation to the vehicle equipped with an anti-lock brake device that adjusts the braking force to maintain the slip state of the theory in a predetermined range,
A speed ratio control device of a type that determines a target value based on at least an actual driving wheel vehicle speed from a relationship stored in advance and adjusts the speed ratio so that the actual engine rotation speed or speed ratio becomes the target value. (A) slip rate detecting means for sequentially detecting the slip rate of the driving wheels; (b) vehicle body deceleration detecting means for sequentially detecting the vehicle body deceleration of the vehicle based on the estimated vehicle speed of the vehicle; (E) first control means for controlling the speed of change of the speed ratio based on the slip ratio; (d) second control means for controlling the speed of change of the speed ratio based on the vehicle body deceleration; During the operation of the anti-lock brake device, it is determined whether the estimated vehicle body speed is in an unstable region or a stable region. If the estimated vehicle speed is in an unstable region, the first control means is selected, and the vehicle is in a stable region. in case of And selection means for selecting the serial second control means is to include.

In this way, during operation of the anti-lock brake device, the first control means is selected by the selection means when the estimated vehicle body speed is in the unstable area, and when the anti-lock brake device is in the stable area. , The second control means is selected. For this reason, in the early stage of the operation of the anti-lock brake in which the estimated vehicle speed is unstable and the vehicle deceleration calculated therefrom is not accurate, the first control means controls the speed ratio change speed based on the slip ratio. On the other hand, in the stable region of the estimated vehicle body speed, the speed ratio change speed is controlled by the second control means based on the vehicle body deceleration. Therefore, in the early stage of the operation of the anti-lock brake device, that is, in a state where the estimated vehicle body speed is unstable due to a sudden drop and it is difficult to obtain the accuracy of the deceleration derived therefrom, the speed is determined based on the relatively stable slip ratio. When the ratio change speed is controlled, and then the estimated vehicle speed is stably obtained and the accuracy of the deceleration obtained therefrom increases, the speed ratio change speed is controlled based on the deceleration corresponding to the road surface friction. Therefore, stable gear ratio change speed control can be performed from the beginning of braking of the anti-lock brake device, and, for example, during the operation of the anti-lock brake device, when the road surface friction coefficient is significantly lower than the road surface friction coefficient from a frozen road surface that is significantly low. When the vehicle stops, the speed ratio of the continuously variable transmission shifts to the most deceleration side even if the road changes to a snow-covered road with a slightly larger road friction coefficient. It has been, so that the driving force at the time of re-start of the vehicle can be sufficiently obtained.

Here, the first control means preferably determines a target change speed of the speed ratio based on an actual slip ratio from a relationship obtained in advance, and the actual speed ratio change speed becomes the target change speed. Is controlled as follows.

Preferably, the second control means determines a target change speed of the speed ratio based on an actual vehicle deceleration from a relationship obtained in advance, and the actual speed ratio change speed becomes the target change speed. The speed ratio is controlled.

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

In FIG. 1, the rotation of the engine 10 is transmitted to a belt-type continuously variable transmission (CVT) 16 via a fluid coupling 14 having a lock-up clutch 12 arranged in parallel. After the speed is changed steplessly, it is transmitted to left and right drive wheels (front wheels) 22 and 24 via a forward / reverse switching device 18 and a differential gear device 20.

In the fluid coupling 14, the lock-up clutch 12 is released or engaged by changing the flow direction of the hydraulic oil supplied from the CVT hydraulic control circuit 26. The CVT hydraulic control circuit 26 is configured, for example, similarly to the hydraulic control circuit described in Japanese Patent Application Laid-Open No. 61-2957 and the hydraulic control circuit described in Japanese Patent Application Laid-Open No. 64-49749.

Further, the belt-type continuously variable transmission 16 includes an input shaft 28 frozen by the engine 10 via the fluid coupling 14,
An output shaft 30 connected to the left and right drive wheels 22 and 24 via the forward / reverse switching device 18 and the differential gear device 20, and a pair of variable effective diameters provided on the input shaft 28 and the output shaft 30, respectively. Variable pulleys 32 and 34 and a transmission belt 36 wound around the pair of variable pulleys 32 and 34 are provided. For this reason, the hydraulic oil is supplied to one of the pair of hydraulic cylinders that apply the clamping force (thrust) between the pair of variable pulleys 32 and 34 by the CVT hydraulic control circuit 26, and the hydraulic oil is discharged from the other. , Speed ratio e (= rotation speed N _out of output shaft 30 / rotation speed of input shaft 28)
N _in ) can be changed.

The forward / reverse switching device 18 includes a planetary gear mechanism, a forward-use clutch, and a reverse brake. A manual valve 38 mechanically interlocked with a shift lever 37 causes a forward range such as a D range or an R range. By selectively operating the forward clutch or the reverse brake in accordance with the operating oil supplied in response to the operation of the vehicle, the vehicle is allowed to move forward or backward. When the shift lever 37 is operated to the P range or the N range and the forward clutch and the reverse brake cannot be operated together, the forward / reverse switching device 18
The power transmission is interrupted inside.

A signal indicating the engine rotation speed _Ne is output from the engine rotation sensor 40 for detecting the rotation speed of the engine 10, and a signal indicating the throttle valve opening θ is output from the throttle sensor 42 for detecting the required output to the engine 10. , Input shaft
A signal indicating the input shaft rotation speed N _in is output from the first rotation sensor 44 for detecting the rotation speed of the output shaft 28, and the output shaft rotation speed N in output from the second rotation sensor 46 for detecting the rotation speed of the output shaft 30. A signal indicating “ _out” and a signal indicating a brake operation are supplied from a brake sensor 50 for detecting operation of the brake pedal 48 to an ECU (electronic control unit) 51 for CVT. The CVT ECU 51 is a so-called microcomputer including a CPU, a ROM, and a RAM.The CPU processes an input signal in accordance with a program stored in a ROM in advance while utilizing a storage function of the RAM, and executes the hydraulic control for the CVT. The engagement state of the lock-up clutch 12 in the circuit 26, the belt-type continuously variable transmission
16 speed ratio etc. are controlled.

For example, in the CVT ECU 51, regarding the lockup clutch 12, the actual reduction ratio of the forward / reverse switching device 18 and the differential gear device 20, the diameter of the drive wheel, etc., stored in advance, based on the output shaft rotation speed _Nout , are used. Vehicle speed (drive wheel speed) SPD
On the other hand, when the actual vehicle speed SPD exceeds a predetermined comparatively low reference vehicle speed for engagement, for example, 20 km / h, the lock-up clutch 12 is engaged, and the actual vehicle speed SP
D is a relatively low predetermined reference vehicle speed at the time of release,
For example, when the speed falls below 15 km / h, the lock-up clutch 12 is released.

In the CVT ECU 51, regarding the belt-type continuously variable transmission 16, the actual throttle valve opening θ and the actual throttle valve opening θ are determined based on a relationship stored in advance for operating the engine 10 along an optimal curve in consideration of fuel efficiency and driving performance. The target input shaft rotation speed N _in ^* is determined based on the vehicle speed SPD, and the speed of the belt-type continuously variable transmission 16 is adjusted so that the target input shaft rotation speed N _in ^* matches the actual input shaft rotation speed N _in. The ratio is adjusted.
Alternatively, the input shaft rotation speed N _in and the output shaft rotation speed N _out
After the actual speed ratio e of the belt-type continuously variable transmission 16 is calculated from the actual throttle valve opening θ and the vehicle speed SPD based on a relationship stored in advance for operating the engine 10 along the optimal curve. Thus, the target speed ratio e ^* is determined, and the speed ratio e of the belt-type continuously variable transmission 16 is adjusted such that the target speed ratio e ^* matches the actual speed ratio e. Target speed ratio e ^*, the target input shaft rotational speed N _in ^*, and between the output shaft speed N _out corresponding to the vehicle speed _{^{SPD, e * = N out /}} N in *
Therefore, the former control and the latter control are substantially the same. FIG. 2 shows an example of the above relationship.

On the other hand, the vehicle of the present embodiment is provided with an anti-lock brake device that automatically adjusts the brake fluid pressure so as to maintain the slip state of the wheels within a predetermined range in relation to the braking operation. That is, the left and right front wheels 22 and
24 and left and right rear wheels 52 and 54 are provided with wheel rotation sensors 56, 58, 60 and 62 for detecting respective rotation speeds, and the wheel rotation sensors 56, 58 and 6 are respectively provided.
From 0 and 62, signals representing the rotational speeds of the wheels 22, 24, 52 and 54 are supplied to an ABS ECU (electronic control unit) 64. Further, a signal indicating a brake operation from the brake sensor 50 is supplied to the ABS ECU 64. ECU64 for ABS
Is a so-called microcomputer including a CPU, a ROM, and a RAM.
Processes the input signal according to the program stored in the
It controls the S hydraulic pressure control circuit 66 and the like. For example, on the condition that the braking operation is started, the estimated vehicle speed _VSO is calculated from the rotational speed of the wheel that is not slipping the most, and the estimated vehicle speed _VSO and the actual rotational speed of each wheel during braking are calculated. The slip ratio S [= (V _SO −V _Wmean ) / V _SO ] of the drive wheel is calculated based on the vehicle speed V _Wmean from the (average value), and if the slip ratio S is larger than a predetermined value, ABS The control is started to output the ABS operation signal A _ABS, and the slip ratio S is set within a predetermined range.
The ABS hydraulic control circuit 66 controls the braking force of each wheel.
The predetermined range is a predetermined region in which a large road surface friction coefficient μ can be maintained and a cornering force can be secured. As is well known, an ABS hydraulic control circuit 66 is provided between a master cylinder 68 having pumps, dampers, reservoirs, control valves, and the like, and wheel cylinders 70, 72, 74, 76 provided on each wheel. And controls the braking force of each wheel by reducing, increasing, or holding the hydraulic pressure to each of the wheel cylinders 70, 72, 74, 76 in accordance with a command from the ABS ECU 64.

The operation of the ECU 51 for the CVT and the ECU 64 for the ABS will be described below with reference to the flowcharts of FIGS.

FIG. 3 shows a predetermined time, for example, 8 m in the ECU 64 for ABS.
9 shows an interrupt routine that is repeatedly executed every s. First, in step SA1, for example with the estimated vehicle speed V _SO it is calculated from the four rotational speeds of the most slip little wheel among the wheels, calculated vehicle speed V _Wmean from the actual rotational speed of each wheel (average value) Is done. Then, in step SA2, the slip ratio of the driving wheels based on the vehicle speed V _Wmean from the actual rotational speed of the estimated vehicle speed V _SO and the wheels S _{[= (V SO -V Wmean) /} V SO ] is calculated At the same time, the slip ratio S is output from the ECU 64 for ABS to the ECU 51 for CVT. In step SA3, the difference ΔV _(i) between the previous estimated vehicle speed V _{SO (i-1)} and the current estimated vehicle speed V _{SO (i)} is obtained from the following equation (1). N times (for example, 3 to 4 ₎ before the difference ΔV _(i)
The vehicle deceleration G is obtained by calculating the average value from the value ΔV _{(i-1) of the} previous rotation ₎ to the current value ΔV _{SO (i} ) according to the following equation (2). ECU64 to CV for ABS
Output to ECU 51 for T.

ΔV _(i) = ΔVSO _(i) −VSO _(i-1) (1) Here, Δt is an interrupt cycle of this routine, and C is a constant.

In the present embodiment, the ABS ECU 64 functions as slip ratio detecting means and vehicle body deceleration detecting means.

FIG. 4 shows a predetermined time, for example, 8 m, in the ECU 51 for CVT.
9 shows an interrupt routine repeatedly executed every s.
First, whether or not the ABS operation of the antilock brake system is determined based on the ABS operation signal A _ABS from the ABS ECU64 at Step SB1. In step SB1, after being contents of the speed ratio change velocity V _c is at its maximum value at step SB2, if it is determined that it is not in ABS operation, the present interrupt routine is terminated, the ABS operation If it is determined that
It is determined whether or not the elapsed time from the start of the BS operation (the turning on of the ABS operation signal _ABS ) is larger than a predetermined reference value α. This determination reference value α is for determining whether or not the estimated vehicle speed _VSO is within an unstable range,
This is a value obtained experimentally in advance.

In step SB3, if the elapsed time from the ABS operation start is not greater than the determination reference value α, so is the unstable region of the estimated vehicle speed V _SO, in step SB4, the previously stored The speed ratio change speed _Vc is obtained from the relationship of FIG. 5, but if it is determined that the elapsed time from the start of the ABS operation is larger than the determination reference value α, the stable region of the estimated vehicle speed _VSO is determined. Therefore, in step SB5, the speed ratio change speed _Vc is obtained from the relationship previously stored in FIG. The relationship between FIG. 5 and FIG. 6 is obtained in advance in order to surely change the speed ratio e toward the maximum deceleration side without generating the feeling of engine braking when the vehicle stops.

FIG. 7 also shows a predetermined time, for example, 8 m, in the ECU 51 for CVT.
9 shows an interrupt routine repeatedly executed every s.
In the figure, in step SC1, the target speed ratio e ^* is determined based on the actual throttle valve opening θ and the driving wheel vehicle speed SPD from the relationship stored in advance shown in FIG. 2, and in step SC2, the target speed ratio e ^* is stored in advance. speed ratio changing speed V _n is determined based on the actual speed ratio e and the target speed ratio e ^* and the deviation Δe from the relationship. As the above relationship, for example, a proportional expression V _n = K · Δe is used.

In the following step SC3, the speed ratio change velocity V _c determined in routine of FIG. 4 is whether or not the determined speed ratio change velocity V _n or more in step SC2 is determined. In step SC3, when it is determined that V _c ≧ V _n is the contents of the target speed ratio changing speed V _cvt is the speed ratio change velocity V _n on the basis of the deviation Δe in step SC4, V _c <If it is determined that V _n is the step SB2, SB4, SB5 speed ratio changing speed V _c determined in the contents of the target speed ratio changing speed V _cvt said Figure 4 in step SC5 You. And step SC
In 6, the actual speed ratio changing speed V _c is the speed change control valve apparatus of a CVT hydraulic control circuit 26 so that the target speed ratio changing speed V _cvt determined as described above is adjusted. As described above, in the present embodiment, the ECU 51 for CVT uses the slip ratio S
First control means for controlling the change speed of the speed ratio e based on the vehicle speed; second control means for controlling the change speed of the speed ratio e based on the vehicle body deceleration G; It is determined whether the speed _VSO is in an unstable region or a stable region. If the speed _VSO is in the unstable region, the first control means is selected. If the speed _VSO is in the stable region, the second control means is selected. Each functions as a means.

As described above, according to the vehicle of the present embodiment, during the operation of the antilock brake device, the speed ratio changing speed is controlled based on the relationship in FIG. Since the vehicle body deceleration G corresponds to the road surface friction coefficient, by controlling the speed ratio changing speed based on the vehicle body deceleration G as described above, for example, during operation of the antilock brake device, When the vehicle stops, the speed ratio of the continuously variable transmission is returned to the most decelerating side even if the vehicle changes from a frozen road surface with a significantly low friction coefficient to a snow-covered road surface with a road surface friction coefficient slightly larger than the road surface friction coefficient. Thus, a sufficient driving force can be obtained when the vehicle restarts. In short, during ABS control, since the slip rate is controlled so that the friction coefficient of the wheel becomes the maximum, the maximum deceleration on the road surface can be obtained, so it is possible to respond to the road surface friction resistance based on the vehicle deceleration G during ABS control The speed ratio e can be changed at the changed speed ratio changing speed.

Further, according to the vehicle of the present embodiment, during the operation of the antilock brake system, in step SB3 that functions as a selection unit, when it is determined that the unstable region of the estimated vehicle speed V _SO, first control means Step SB functioning as
4 is selected, but if it is determined that the region is a stable region, the second
Step SB5 functioning as control means is selected. For this reason, in the early stage of the operation of the antilock brake in which the estimated vehicle speed _VSO is unstable and the vehicle body deceleration G calculated therefrom is not accurate, the fifth step SB4 is performed.
Speed ratio change speed based on the relationship in the figure and the slip ratio S
While V _c is controlled in a stable region of the estimated vehicle speed V _SO is the speed ratio change velocity V _c is controlled based on the first six view relationships and vehicle deceleration G in step SB5. Therefore, in the early stage of the operation of the anti-lock brake device, that is, in a state where the estimated vehicle speed _VSO is unstable and the accuracy of the deceleration G derived therefrom is difficult to obtain, the speed ratio is determined based on the slip ratio S which is relatively stable. When the change speed _Vc is controlled, and then the estimated vehicle speed _VSO is stably obtained and the accuracy of the deceleration G obtained from the speed becomes higher, the speed ratio change speed V is determined based on the deceleration corresponding to the road surface friction. _{Since c} is controlled, the speed ratio change speed _Vc is stably controlled even during the initial period of operation of the antilock brake device.

As mentioned above, although one Example of this invention was described based on drawing, this invention is applied also in another aspect.

For example, in the above-described embodiment, when the estimated vehicle speed _VSO is unstable in the early stage of the operation of the antilock brake device, the speed ratio changing speed is controlled based on the slip ratio S from the relationship shown in FIG. However, when the estimated vehicle speed _VSO is unstable, the speed ratio change speed control is not executed by fixing the speed ratio change speed to a predetermined speed, and the anti-lock brake operation is not performed. After a time has elapsed from the start, the speed ratio change speed control may be executed based on the actual vehicle deceleration from the relationship shown in FIG.
In such a case, the step SB4 becomes unnecessary.

In the above-described embodiment, a signal representing the slip rate S and a signal representing the vehicle body deceleration G are output from the ABS ECU 64 functioning as the slip rate detecting means and the vehicle body deceleration detecting means.
It is configured to be transmitted to the CVT ECU 51, but the CVT
A signal from the wheel rotation sensors 56, 58, 60, 62 may be supplied to the ECU 51, and the slip ratio S and the vehicle body deceleration G may be calculated in the CVT ECU 51.

In the above-described embodiment, the belt-type continuously variable transmission 16
However, other types of continuously variable transmissions may be used.

Further, in the above-described embodiment, the case of the FF vehicle is used, but the present invention can be applied to the case of an FR vehicle.

The above 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 the drawings]

FIG. 1 is a block diagram showing a power transmission control mechanism and a brake control mechanism of a vehicle including an embodiment of the present invention. FIG. 2 is a diagram showing a relationship used for the speed ratio control of FIG. FIG. 3, FIG. 4 and FIG.
It is a flowchart which shows the principal part of the control operation | movement in the Example of a figure, respectively. FIG. 5 and FIG. 6 are diagrams showing the relationship used in the operation of the flowchart of FIG. 10: Engine 16: Belt-type continuously variable transmission (Continuously variable transmission) 22: Left front wheel (drive wheel) 24: Right front wheel (drive wheel) 51: ECU for CVT (first control means, second control means, selection Means) 64: ABS ECU (Slip rate detecting means, vehicle body deceleration detecting means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display F16H 59:44 59:48 59:54

Claims (1)

(57) [Claims] 1. A continuously variable transmission for continuously changing the rotation of an engine and transmitting the rotation to drive wheels, and a braking force for maintaining a slip state of wheels in a predetermined range in relation to a braking operation of the vehicle. In a vehicle equipped with an anti-lock brake device for adjusting, a target value is determined based on at least the actual driving wheel speed from a relationship stored in advance, and the actual engine speed or speed ratio is set to the target value. A speed ratio control device for adjusting a speed ratio, comprising: a slip ratio detecting means for sequentially detecting a slip ratio of a drive wheel; and a vehicle body for sequentially detecting a vehicle body deceleration of the vehicle based on an estimated vehicle speed of the vehicle. Deceleration detecting means, first control means for controlling the speed of change of the speed ratio based on the slip ratio, second control means for controlling the speed of change of the speed ratio based on the vehicle body deceleration, During the operation of the anti-lock brake device, it is determined whether the estimated vehicle speed is in an unstable region or a stable region. If the estimated vehicle speed is in the unstable region, the first control means is selected. A speed ratio control device for a continuously variable transmission for a vehicle, comprising: selecting means for selecting the second control means when the area is the area.