JP2002213604A - Device for controlling speed change at braking of transmission with infinite gear ratio - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a stall, even when wheels are locked before a transmission with infinite gear ratio completes a gear shift to a neutral position through quick braking. SOLUTION: When a gear ratio reaches a rotation synchronizing point by braking (a brake switch 47 is turned on) at an instant t1 and a command to switch from a direct connection mode to a power circulating mode is generated, a high clutch is made to be released, but a low clutch is prevented from engaging. The transmission is brought to neutral position by prohibiting engagement of the low clutch as well as switching the high clutch from engagement to releasing for preventing engine stall due to gear shift lag to the neutral position, even if the wheels are locked at braking. During this time, a target CVT gear ratio icvto is controlled, such that the relative rotation of the low clutch becomes zero. These controls are completed, when the state becomes accelerator pedal stepped state (after an instant t3) to open a throttle opening TVO. Then the low clutch is allowed to be engaged for preventing re-engagement shock of the low clutch, since the relative rotation of the low clutch becomes zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for preventing engine stall during braking of an infinite speed ratio transmission.

[0002]

2. Description of the Related Art As an infinite speed ratio transmission, for example, one described in Japanese Patent Application Laid-Open No. Hei 10-267116 is known, and an infinite speed ratio transmission is usually provided as shown in FIG. A continuously variable transmission a such as a toroidal type continuously variable transmission or a V-belt type continuously variable transmission is combined with a planetary gear set b. That is, the input rotation to the continuously variable transmission a is transmitted to one of the three elements (the first element: the carrier in FIG. 9) of the planetary gear set b via the constant transmission c and the low power clutch d for power circulation. While circulating power from the output rotary member of the continuously variable transmission a to the input rotary member via another element (the second element: sun gear in FIG. 9) of the planetary gear set b, the circulating power is transmitted to the planetary gear set a. The remaining one element (third element: ring gear in FIG. 9) is taken out and output rotation is performed (power circulation mode), the above-mentioned low clutch d is released, and the high clutch e directly connected to the continuously variable transmission is engaged instead. Thus, the power of the continuously variable transmission from the output rotating member of the continuously variable transmission a is normally directly taken out through the high clutch e (direct connection mode).

In such a configuration, the speed ratio (input speed Nin / output speed Nout) of the infinite speed ratio transmission is
The speed ratio Et (Nout / Nin) of the infinitely variable transmission (IVT), which is the reciprocal of the transmission ratio, and the continuously variable transmission (CV)
As shown in FIG. 8 exemplifying the relationship between T) a and the speed ratio icvt, the speed can be controlled by the speed ratio icvt of the continuously variable transmission a.

[0004] In addition, the mode switching between the power circulating mode and the direct connection mode, which is performed by switching the engagement and disengagement of the low clutch d and the high clutch e, depends on the rotational speed of the drive-side rotating members of both clutches and the driven-side rotation. In the power circulation mode in which the IVT speed ratio Et is set to a lower speed ratio than the rotation synchronization point RSP, the stepless transmission a is executed at the rotation synchronization point RSP where the rotation speed of the member coincides.
Is set to a certain speed ratio, the rotation transmitted to the third element (ring gear) of the planetary gear set b becomes zero, and the output speed Nout of the infinite speed ratio transmission becomes zero (GNP:
(Neutral point), gear ratio (transmission input rotation speed / transmission output rotation speed) with the transmission path mechanically connected
Can create an infinite state and can be stopped.

In this power circulation mode, when the continuously variable transmission a has a higher (higher) gear ratio than the gear ratio at which the rotation of the third element (ring gear) of the planetary gear set b is reduced to zero,
The output rotation of the infinite speed ratio transmission is reversed to enable reverse traveling, and the speed ratio infinite as the speed ratio icvt of the continuously variable transmission a is lower (lower) than the speed ratio. The output rotation of the large transmission is increased in the number of rotations in the forward rotation direction (the transmission ratio of the infinitely variable transmission becomes a higher-speed transmission ratio), thereby enabling forward traveling. During forward running, when the speed ratio icvt of the continuously variable transmission a reaches the certain speed ratio on the low speed side, in the power circulation mode, the rotational speeds of the second and third elements of the planetary gear set e (the drive side of the high clutch) And the number of rotations of the non-drive-side rotary member) coincide with each other to reach the above-mentioned rotation synchronization point RSP. At this time, the high clutch e is engaged by supplying hydraulic pressure, and the low clutch d is released by removing hydraulic pressure. In theory, it is possible to switch from the power circulation mode to the direct connection mode without shock. In the direct connection mode, the shift by only the continuously variable transmission a is reflected on the shift of the infinite speed ratio transmission.

Conversely, when the mode is switched from the direct connection mode to the power circulation mode, the rotational speeds of the drive side and the non-drive side rotary members of the low clutch d coincide with each other at the above-mentioned rotation synchronization point RSP. By engaging the clutch d and releasing the high clutch e, the mode can be switched theoretically without any shock. Naturally, when both the low clutch d and the high clutch e are released, the transmission input rotational speed N
Since in is not transmitted to the rear of these clutches, the infinite transmission ratio transmission does not perform power transmission (output rotation speed Nout = 0) and enters a neutral state.

[0007]

Here, the shifting operation when stopping the vehicle by operating the brake will be described with reference to FIG. At the time of braking during traveling in the direct connection mode with the high clutch engaged, the rotation synchronization point R
When the shift to SP is completed, the high clutch is disengaged and the low clutch is engaged. The shift from the direct connection mode to the power circulation mode is performed by changing the clutch, and the shift to the neutral point GNP is completed with further deceleration. When you stop, it is possible to stop. Further, during braking in the power circulation mode in which the low clutch is engaged, the vehicle can be stopped when the shift to the neutral point GNP is completed with deceleration.

When the wheels are locked, for example, during sudden braking or traveling on a low-friction road, the output speed Nout of the infinite speed ratio transmission decreases rapidly irrespective of the vehicle speed and finally ends up. The transmission output speed Nout becomes zero before the shift to the neutral point GNP in the power circulation mode is completed because the transmission speed cannot catch up with the decreasing speed of the transmission output speed Nout. In this case, the above-mentioned power circulation becomes impossible, so that a so-called engine stall occurs in which the engine is stopped by being dragged to the transmission output rotational speed Nout = 0.

The first aspect of the present invention is a neutral state in which no wheel driving force is required during braking of the vehicle, and both the low clutch and the high clutch are disengaged and power cannot be transmitted to the infinite speed ratio transmission. In the power circulation mode where the low clutch should be engaged, the braking is prohibited during braking and the infinite transmission ratio transmission is set to the neutral state, so that the wheels are locked during braking. SUMMARY OF THE INVENTION It is an object of the present invention to propose a braking shift control device for a transmission with an infinitely variable gear ratio that solves the above-described problem without causing engine stall.

According to a second aspect of the present invention, when the above-described inhibition of the engagement of the low clutch is released only under the condition that the braking is released, not only the engine brake acts when the low clutch is re-engaged, but also a feeling of strangeness is given. Because the engine stalls during re-braking after the release of braking, the gear ratio is infinitely large, in which not only the release of braking but also the condition that the prime mover is loaded is added as a condition to release the prohibition of engagement of the low clutch. It is an object of the present invention to propose a speed change control device during braking of a high speed machine.

According to a third aspect of the present invention, there is provided a speed change control device for braking an infinitely variable transmission having a low clutch that can reduce an engagement shock when the low clutch is reengaged by releasing the engagement prohibition. The purpose is to propose.

According to a fourth aspect of the present invention, there is provided a speed change ratio in which an engagement shock when the low clutch is re-engaged by canceling the engagement prohibition can be reduced by means different from the third invention. It is an object of the present invention to propose a shift control device during braking of an infinite transmission.

[0013]

SUMMARY OF THE INVENTION For these purposes, the braking shift control device for an infinite transmission ratio transmission according to a first aspect of the present invention provides a continuously variable transmission and a planetary gear set when a low clutch for power circulation is engaged. By the cooperation, it is possible to realize a low-speed gear ratio including an infinite gear ratio, which is lower than a certain gear ratio. A transmission ratio infinite transmission that can realize a transmission ratio higher than the transmission ratio and that is in a neutral state in which power is not transmitted when the low clutch for power circulation and the high clutch for direct connection to a continuously variable transmission is released. At the time of braking of the vehicle, even if the vehicle shifts from an operating region in which the high-speed side gear ratio should be realized to an operating region in which the low-speed side gear ratio should be realized,
It is characterized in that the engagement of the low clutch for power circulation is prohibited.

In the first aspect of the present invention, when the engine is put into a load state after the braking state is released, the power transmission low clutch is engaged. The prohibition is released.

According to a third aspect of the present invention, there is provided a speed change control device for braking an infinite speed ratio transmission according to the first or second aspect.
While the engagement of the power circulation low clutch is prohibited, the speed of the continuously variable transmission is controlled so that the rotation difference between the input / output rotation members of the power circulation low clutch is eliminated.

According to a fourth aspect of the present invention, there is provided a speed change control device for braking an infinitely variable speed ratio transmission according to the first or second aspect.
While the engagement of the power circulation low clutch is prohibited, the output of the prime mover is controlled so that the rotation difference between the input and output rotary members of the power circulation low clutch is eliminated.

[0017]

The infinite speed ratio transmission includes an infinite speed ratio lower than a certain speed ratio due to the cooperative operation of the continuously variable transmission and the planetary gear set when the low clutch for power circulation is engaged. A low-speed side gear ratio is realized, and a high-speed side gear ratio than the above-mentioned certain gear ratio is realized only by the stepless transmission by fastening the high clutch for direct connection to the stepless transmission. The neutral state in which power transmission is not performed by releasing the high clutch directly connected to the transmission.

In the braking shift control device according to the first aspect of the invention, when the vehicle is in the braking state, the operation shifts from the operating region in which the high-speed gear ratio is to be realized to the operating region in which the low-speed gear ratio is to be realized. However, in order to prohibit the engagement of the low clutch for power circulation, not only the high clutch for direct connection to the continuously variable transmission but also the low clutch for power circulation are released during the braking of the vehicle in the operating region where the low speed side gear ratio should be realized. As a result, the infinite transmission ratio transmission is in the neutral state, and even when the wheels are locked during braking, no engine stall occurs due to a delay in shifting to the neutral point. The above-mentioned problem can be solved. When the vehicle is braked, no wheel driving force is required, and there is no practical problem even if the infinite transmission ratio transmission is in the neutral state as described above.

In the second invention, the prohibition of the engagement of the low-power-circulation clutch is released when the prime mover is put into a load state after the release of the braking state. As a condition for releasing, not only the release of the braking but also a condition that the prime mover is put in the load state is added, and when the above-mentioned prohibition of the engagement of the low clutch for power circulation is released only under the condition of releasing the braking state, When the low clutch for power circulation is re-engaged at this time, the engine brake acts to give a sense of incongruity, or an engine stall occurs at the time of re-braking after the braking is released, but these problems can be avoided.

In the third aspect of the present invention, the speed of the continuously variable transmission is controlled so that the rotation difference between the input and output rotary members of the power circulation low clutch is eliminated while the engagement of the power circulation low clutch is prohibited. It is possible to reduce an engagement shock when the low clutch is re-engaged by canceling the engagement prohibition.

In the fourth aspect of the present invention, the output of the prime mover is controlled so that the rotation difference between the input and output rotary members of the power circulation low clutch is eliminated while the engagement of the power circulation low clutch is prohibited. The engagement shock at the time of re-engagement due to cancellation of the engagement prohibition can be reduced by means different from the third invention. Here, when the continuously variable transmission is made to eliminate the rotation difference between the input and output rotating members of the low clutch for power circulation by speed change control as in the third invention, the target is set when returning from the speed change control to the normal speed change control. Although the gear ratio changes in a step-like manner, giving a sense of incompatibility. In the fourth invention, the sudden change in the target gear ratio does not occur, and the incompatibility can be avoided.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an infinite speed ratio transmission including a speed change control device during braking according to an embodiment of the present invention, and a speed change control system thereof. The infinitely variable transmission IVT shown in FIG. 1 is configured as a transaxle for a front engine / front wheel drive vehicle (FF vehicle) in which the engine is mounted horizontally, and a toroidal type transmission disposed on the input shaft 1 is provided. The main components are the step transmission 2 and the planetary gear set 4 on the output shaft 3 arranged in parallel with the step transmission 2.

The toroidal-type continuously variable transmission 2 has two toroidal transmission units 5 and 6, that is, a front toroidal transmission unit 5 and a rear toroidal transmission unit 6 as main components, and these toroidal transmission units 5 and 6 are used. Respectively, an input disk 7 fitted so as to rotate integrally with the input shaft 1, an output disk 8 rotatably supported on the input shaft 1 between these input disks, and an input disk 7 between the corresponding input / output disks 7, 8. It comprises a power roller 9 for transmitting power. Two power rollers 9 are provided for each of the toroidal transmission units 5 and 6, and these are arranged on both sides of the input shaft 1 so as to face each other, and are rotatably supported by individual trunnions (not shown) via a pivot shaft 11. The upshift hydraulic pressure Pup and the downshift hydraulic pressure P
Strokes can be made at the same phase in synchronization with the trunnion axis direction (perpendicular to the direction of FIG. 1) by a piston that responds to the differential pressure between dn.

In FIG. 1, the engine rotation transmitted from the engine ENG to the input shaft 1 via the flywheel 10 reaches both input disks 7, and the engine rotation (input rotation of the transmission) to the input disk 7 is performed by the power roller 9. The power is transmitted to the output disk 8 via a sprocket 12 fixed to both output disks 8. During this transmission, the trunnion is synchronously stroked in the same phase in the direction of the trunnion axis (oscillating axis) orthogonal to the power roller rotation axis by the differential pressure between the upshift oil pressure Pup and the downshift oil pressure Pdn. When the power roller rotation axis is shifted from the equilibrium position (non-transmission position) where the rotation axis crosses the rotation axis of the input / output disks 7 and 8 to the transmission position offset from the rotation axis of the input / output disks 7 and 8, the power roller 9 is moved. It is tilted in phase around the swing axis in synchronization. As a result, the radius of the contact trajectory circle of the power roller 9 with respect to the input / output disks 7 and 8 continuously changes, and the transmission ratio between the input / output disks 7 and 8 (CVT speed ratio i)
cvt) can be changed steplessly.

The pressure difference between the upshift oil pressure Pup and the downshift oil pressure Pdn is determined by the step motor 22 in the control valve body 21 which is set at the target CVT speed ratio i.
It is generated by operating a shift control valve (not shown) from a neutral position by stroke to a position corresponding to cvto. Then, the shift progress state by the differential pressure is determined by the servo system 23.
Feedback to the speed change control valve by the CVT speed ratio i
When the cvt reaches the target CVT gear ratio icvto, the shift control valve is returned to the neutral position, and the power roller 9 is returned to the non-shift position where the offset is 0, thereby obtaining the CVT.
The gear ratio icvt can be maintained at the target gear ratio icvto.

Next, the construction of the planetary gear set 4 provided on the output shaft 3 of FIG. 1 and the above-described toroidal-type continuously variable transmission 2 will be described. A low clutch 31 as a power circulating clutch is disposed adjacent to the front side of the planetary gear set 4 near the engine, and a sprocket 32 and a high clutch 33 as a directly-coupled continuously variable transmission clutch are sequentially arranged at the rear side far from the engine of the planetary gear set 4. Arrange adjacently. The sprocket 32 is rotatably supported on the output shaft 3, and a chain 34 extends between the sprockets 12 and 32.

The planetary gear set 4 is a simple planetary gear set including a sun gear 4s, a carrier 4c, and a ring gear 4r. The sun gear 4s is rotatably supported on the output shaft 3 and is connected to a sprocket 32. The carrier 4c has an input shaft 1
The input gear of the transmission is input through the reduction gear set 35 and the low clutch 31, the ring gear 4r is connected to the output shaft 3, and the sprocket 32 is connected to the high clutch 33.
Can be connected to the output shaft 3. And on the output shaft 3,
A differential gear device 37 is drivingly connected via a final drive gear set 36.

The operation of the thus-configured infinite speed ratio transmission IVT shown in FIG. 1 will now be described. In the control valve body 21, in addition to the step motor 22, a low clutch solenoid 24 for engaging and disengaging the low clutch 31 and a high clutch solenoid 25 for engaging and releasing the high clutch 33 are provided. The low clutch solenoid 24 is turned on. At this time, the low clutch 31 is engaged by the generation of the low clutch pressure Po, and the high clutch 33 is engaged by the generation of the high clutch pressure Ph when the high clutch solenoid 25 is ON.

When the low clutch solenoid 24 is turned on, the low clutch 31 is engaged, and the high clutch solenoid 2
When the high clutch 33 is released by turning off the gear 5, the transmission input rotation to the input shaft 1 is transmitted to the carrier 4c of the planetary gear set 4 via the reduction gear set 35 and the low clutch 31. The transmission input rotation transmitted to the carrier 4c is distributed to the sun gear 4s and the ring gear 4r.
s is circulated through the chain 34 from the output disks 8 of the toroidal transmission units 5 and 6 to the input disk 7 and the input shaft 1, and the circulating power is transmitted to the ring gear 4.
This enables power transmission in the power circulation mode for transmitting power from the motor r to the output shaft 3.

When the low clutch 31 is released by turning off the low clutch solenoid 24 and the high clutch 33 is engaged by turning on the high clutch solenoid 25, the input disk 7 of the two toroidal transmission units 5, 6 , And the output rotation of the toroidal continuously variable transmission 2 that reaches the chain 34 via the output disk 8 reaches the output shaft 3 via the high clutch 33, and the output rotation of the toroidal continuously variable transmission 2 is directly controlled. Power transmission in the direct connection mode taken out from the output shaft 3 becomes possible.

The rotation to the output shaft 3 reaches the drive wheels 38 via the final drive gear set 36 and the differential gear device 37, and causes the vehicle to run.

In the power circulation mode with the low clutch 31 engaged, as shown in FIG. 8, the CVT speed ratio icvt of the toroidal type continuously variable transmission 2 is set to a speed ratio at which the rotation of the ring gear 4r becomes zero. As a result, the output rotation Nout of the infinite speed ratio transmission becomes 0 (referred to as a neutral point GNP), and the IVT speed ratio Et ( Transmission output rotation speed Nout / transmission input rotation speed Nin) is 0 (Nin /
A state (stop state) in which the speed ratio represented by Nout is infinite) can be created. In the power circulation mode, when the toroidal type continuously variable transmission 2 has a higher (higher) side gear ratio than the gear ratio at which the rotation to the ring gear 4r is set to 0, the output of the infinite gear ratio transmission is obtained. Rotation Nout
In the reverse direction to enable reverse travel, and the output rotation of the infinitely variable transmission becomes larger as the CVT transmission ratio icvt of the toroidal continuously variable transmission 2 is lower (lower) than the transmission ratio. Nout is increased in the number of revolutions in the normal rotation direction to enable forward traveling.

Accordingly, the CV of the toroidal type continuously variable transmission 2
When the T speed ratio icvt reaches a certain speed ratio on the low speed side,
In the power circulation mode, the rotational speeds of the sun gear 4s and the ring gear 4r (the rotational speeds of the driving side and the non-driving side rotating members of the high clutch 33) match each other (shown as a rotation synchronization point RSP in FIG. 8). 33 by the supply of the hydraulic pressure Ph and the low clutch 31
Is released by eliminating the hydraulic pressure Po, it is theoretically possible to switch from the power circulation mode to the direct connection mode without any shock.

In the direct connection mode with the high clutch 33 engaged, as shown in FIG. 8, the CVT speed ratio icvt of the toroidal type continuously variable transmission 2 is set to a speed ratio higher than the rotation synchronization point RSP. Transmission ratio infinite transmission IV
The T speed ratio Et can be directly controlled. When switching from the direct connection mode to the power circulation mode,
At the above-mentioned rotation synchronization point RSP, the rotational speeds of the driving side and the non-driving side rotating members of the low clutch 31 coincide with each other. At this time, by engaging the low clutch 31 and releasing the high clutch 33, there is theoretically no shock. The mode can be switched during the operation.

The drive control of the step motor 22, the ON / OFF control of the low clutch solenoid 24, and the ON / OFF control of the high clutch solenoid 25 are performed by the controller together with the additional torque control of the engine ENG which is the object of the present invention. 41. For this purpose, a signal from a transmission input rotation sensor 42 for detecting the rotation speed Nin of the input shaft 1 and a transmission output rotation for detecting the rotation speed Nout of the output shaft 3 are provided to the controller 41 for this purpose. Sensor 4
3, a signal from a CVT output rotation sensor 44 for detecting an output rotation speed Ncvt of the toroidal type continuously variable transmission 2, a signal from a throttle opening sensor 45 for detecting an engine throttle opening TVO, and a signal from the engine. Revolution N
e, a signal from an engine rotation sensor 46, a signal from a brake / brake switch 47 that is turned on when the brake pedal is depressed, and a signal from an idle switch 48 that is turned on when the accelerator pedal is released.

The controller 41 of FIG. 1 performs a normal shift control by a program not shown based on the various input information described above, and executes the control program shown in FIGS. 2 and 3 to achieve the present invention. The speed change control during braking of the infinite speed ratio transmission is performed. First, a general shift control will be briefly described. A transmission input rotation speed Nin to be a target based on a vehicle speed VSP calculated from the transmission output rotation speed Nout and a throttle opening TVO based on a planned shift map illustrated in FIG. ^The target CVT speed ratio icvto is searched for by assigning the target IVT speed ratio Et ^* obtained by dividing the transmission output rotation speed Nout to the vertical axis in FIG. 22. When the target IVT speed ratio Et ^* reaches the rotation synchronization point RSP in FIG. 8, the mode switching between the power circulation mode and the direct connection mode by changing the clutches 31 and 33 is performed by the solenoids 24 and 25 in FIG. Also command.

Next, a description will be given of the shift control during braking which is aimed at by the present invention as shown in FIGS. 2 and 3. First, in step Sl of FIG. 2, the transmission input rotation speed Nin and the transmission output rotation speed Nout are set. , The CVT output speed Ncvt, the throttle opening TVO, the engine speed Ne, the signal from the brake / brake switch 47, and the signal from the idle switch 48, and in step S2, the vehicle speed VSP is calculated from the transmission output speed Nout. I do. In step S3, it is checked whether or not there is a mode switching command between the power circulation mode and the direct connection mode by changing the clutches 31, 33, and if there is a mode switching command, step S4 is performed.
It is determined whether or not the mode switching command is a command for switching from the direct connection mode to the power circulation mode.

If it is determined in step S4 that the mode switching command is a command for switching from the power circulation mode to the direct connection mode, the shift control for preventing engine stall at the time of sudden braking, which is the object of the present invention, is not necessary. Then, the solenoids 24 and 25 in FIG. 1 are instructed to switch from the power circulation mode to the direct connection mode as usual. Also,
Even if it is determined in step S4 that the mode switching command is a switching command from the direct connection mode to the power circulation mode, if it is determined in step S6 that the brake switch 47 is OFF and the vehicle is not braking, the present invention is aimed at. Since it is not necessary to perform a shift control for preventing engine stall during sudden braking,
At 7, the solenoids 24 and 25 of FIG. 1 are commanded to switch from the direct connection mode to the power circulation mode as usual.

However, if it is determined in step S4 that the mode switching command is a switching command from the direct connection mode to the power circulation mode, and if it is determined in step S6 that the brake switch 47 is ON, braking is being performed. Since the mode switching is performed from the direct connection mode during braking to the power circulation mode which requires the shift control for engine stall prevention at the time of the intended sudden braking, the engagement of the low clutch 31 required in the mode switching is prohibited in step S8. As shown in FIG. 1, the solenoid 24 of FIG. 1 is kept turned off, and only the release of the high clutch 33 is executed by turning off the solenoid 25 of FIG.
Is performed so that the relative rotation difference between the input and output rotary members becomes zero. Hereinafter, the engagement prohibition of the low clutch 31 and the relative rotation difference 0 control in step S8 of FIG. 2 are collectively referred to as braking neutral control.

The operation time chart of the neutral control at the time of braking is as shown in FIG. 4, and the speed ratio reaches the rotation synchronization point RSP (see FIG. 8) at the instant t1 due to the braking (ON of the brake switch 47) and is directly connected. When the switching command from the mode to the power circulation mode is issued, the high clutch 33 is released by switching the high clutch solenoid 25 from ON to OFF.
The engagement of the low clutch 31 by switching OFF → ON of No. 4 is prohibited. Due to the engagement prohibition control of the low clutch 31 in the neutral control at the time of braking, the transmission IVT is set to a neutral state in which power transmission is not performed, in conjunction with the engagement → disengagement switching of the high clutch 33. Even if the wheels are locked, engine stall due to a delay in shifting to the neutral point GNP (see FIG. 8) does not occur, and the above-mentioned problem of the conventional infinite speed ratio transmission can be solved. When the vehicle is braked, no wheel driving force is required, and there is no practical problem even if the infinite transmission ratio transmission is in the neutral state as described above.

Here, the control of the relative rotation difference 0 of the low clutch 31 shown in FIG. 3 will be described.
The T speed ratio icvt = Nin / Ncvt is calculated, and the IVT speed ratio Et = Nout / Nin is calculated in step S22. Next, in step S23, a CVT gear ratio is determined such that the relative rotation speed between the input and output rotation members of the low clutch 31 becomes 0 in the power circulation mode. Incidentally, the line indicating the relationship between the CVT speed ratio icvt and the IVT speed ratio Et in the power circulation mode in FIG. 8 is where the relative rotation speed between the input / output rotation members of the low clutch 31 is set to 0 in the power circulation mode. And therefore step S23
Then, the IVT speed ratio Et obtained in step S22
From the target CVT gear ratio icvto based on FIG.
This is defined as a target CVT speed ratio icvto at which the relative rotation speed between the input and output rotation members of the low clutch 31 becomes 0 in the power circulation mode as after the instant t1 in FIG. In step S24, the target CVT speed ratio icv
CV between to and the current CVT gear ratio icvt
Calculate the T gear ratio deviation e (= icvto-icvt),
In step S25, the CVT speed ratio is feedback-controlled so that this deviation is eliminated.

After the control of step S5 or S7 or S8 in FIG. 2 is started as described above in response to the mode switching command, step S3 determines that there is no mode switching command. In step S9, it is determined whether the neutral control during braking is being performed, in step S10, whether the brake switch 47 is ON or OFF, and in step S11, the idle switch 48
Check whether is ON or OFF. If it is determined in step S9 that the neutral control during braking is not being performed, or if the neutral control during braking is being performed, step S9 is executed.
When the brake switch 47 is determined to be ON with the brake switch 47 at step 10, or as long as the idle switch 48 is determined to be in the ON state of the accelerator pedal released at step S11, the control is terminated as it is.
Alternatively, the control in S8 is continuously executed to complete each control.

When the neutral control during braking is started in step S8 and it is determined in step S9 that the neutral control during braking is being performed, the brake switch 47 is turned off in non-braking in step S10 (at instant t in FIG. 4).
2) and the accelerator pedal is depressed with the idle switch 48 turned off in step S11 (FIG. 4).
The control proceeds to step S12 for the first time (after the prime mover is put in the load state) when it is determined that the instant is after the instant t3, and the braking neutral control started in step S8 is terminated. Therefore, after the braking state is released (instantaneous t2 in FIG. 4), the engine E is depressed by depressing the accelerator pedal.
When the NG (motor) is loaded (the instant t in FIG. 4)
3) For the first time, the engagement prohibition of the low clutch 31 and the relative rotation difference 0 control are released to enable the transmission in the power circulation mode by the engagement of the low clutch 31, and the relative rotation difference of the low clutch 31 is reduced to 0. Is returned to the normal shift control, and the following operation and effect can be obtained.

That is, when the prohibition of the engagement of the low clutch 31 is released only under the condition that the braking state is released, the engine brake acts upon the re-engagement of the low clutch 31 when the braking state is released, giving an uncomfortable feeling or braking. An engine stall will occur at the time of re-braking after the release, but in the present embodiment, not only the release of the braking but also the condition of putting the prime mover in a load state is set as the condition for releasing the prohibition of engagement of the low clutch 31. With the addition, these problems can be avoided.

In the present embodiment, the relative rotation difference 0 control of the low clutch 31 is further added to the neutral control during braking, so that the rotation difference between the input / output rotation members of the low clutch 31 while the engagement of the low clutch 31 is prohibited. When the low clutch 31 is re-engaged by releasing the engagement prohibition in order to control the speed of the toroidal type continuously variable transmission 2 so that
The engagement shock at the instant t3) can be reduced or theoretically eliminated.

When the rotation difference between the input and output rotary members of the low clutch 31 becomes zero while the engagement of the low clutch 31 is prohibited in the neutral control during braking, as described above, the toroidal-type continuously variable transmission 2 is used. Instead of achieving this object by controlling the transmission speed, the same object can be achieved by feedback control of the IVT speed ratio by engine torque control as shown in FIGS. In step S31 of FIG. 5, the engine speed Ne is detected, in step S32 the vehicle speed VSP is calculated from the transmission output speed Nout, in step S33 the IVT speed ratio Et = Nout / Nin is calculated, and in step S34 the throttle is opened. The degree TVO is detected.

Next, in step S35, the transmission output rotation speed No. is calculated based on the target input rotation speed Nin ^* retrieved from the throttle opening TVO and the vehicle speed VSP based on FIG.
ut by dividing the target IVT speed ratio Et ^* = N
out / Nin ^* is calculated. In the next step S36, the target IVT speed ratio Et ^* and the actual IVT speed ratio Et
IVT speed ratio deviation Err = Et ^* −Et
Is calculated, and in step S37, the IVT speed ratio deviation Er
The engine torque increase / decrease ΔT for setting r to 0 is a constant K
Is calculated using ΔT = Err × K.

Further, at step S38, the target engine torque tTe = Te + ΔT is obtained by adding the above-mentioned engine torque increase / decrease amount ΔT to the actual engine torque Te. As is well known, the actual engine torque Te can be obtained from the engine speed Ne in step S31 and the throttle opening TVO in step S34 based on an engine performance diagram. Then, in step S39, as shown in FIG. 1, an instruction is given to the engine ENG to control the throttle opening so that the engine torque becomes the target engine torque tTe.

The operation time chart of the neutral control during braking in this embodiment is as shown in FIG.
Braking (brake switch 4
7), the speed ratio is instantaneously changed to the rotation synchronization point RSP at the instant t1.
(See FIG. 8), when a command to switch from the direct connection mode to the power circulation mode is issued, the high clutch 33 is switched by switching the high clutch solenoid 25 from ON to OFF.
Is released, but the low clutch solenoid 24 is turned off.
→ Prohibiting the engagement of the low clutch 31 by switching ON. With the engagement prohibition control of the low clutch 31 in the neutral control during braking, the engagement of the high clutch 33 is switched from the engagement to the disengagement, and the infinitely variable transmission IVT.
Is in a neutral state in which power is not transmitted, and the neutral point GNP is set even if the wheels are locked during braking.
An engine stall due to a gear shift delay (see FIG. 8) does not occur, and the above-described problem of a conventional infinite speed ratio transmission can be solved.

At the instant t1 for switching from the direct connection mode to the power circulation mode, feedback control of the IVT speed ratio Et by the engine torque control described above with reference to FIG. 5 is started. This control is performed after the instant t2 for releasing the braking. At the instant t3 when the accelerator pedal is depressed, the low clutch 31 is released together with the engagement prohibition.
Meanwhile, the feedback control of the IVT speed ratio Et by the engine torque control described above with reference to FIG. 5 is an engine torque control that maintains the IVT speed ratio Et at the target IVT speed ratio Et ^* , that is, the CV in the power circulation mode of FIG.
This corresponds to control for maintaining the relationship between the T speed ratio icvt and the IVT speed ratio Et on a line. As a result, the low clutch 3
It is possible to theoretically eliminate the engagement shock at the time of releasing the engagement prohibition of the low clutch 31 by maintaining the relative rotation speed between the input / output rotation members of the low clutch 31 at 0 while the engagement prohibition of 1 is prohibited. it can.

However, in the present embodiment, the target CVT speed ratio icvto is set to the normal control value corresponding to the target IVT speed ratio Et ^* even during the braking neutral control, so that the step shown in FIG. It is possible to avoid the uncomfortable feeling that the target CVT speed ratio icvto changes stepwise at the end of the braking neutral control without having.

When the relative rotation difference is reduced to zero while the engagement of the low clutch 31 is prohibited, regardless of whether the shift control as shown in FIG. 3 or the engine torque control as shown in FIG. If the re-engagement due to the release of the prohibition of the engagement of the low clutch 31 seems to be delayed with respect to the end of the control, and the relative rotation difference 0 cannot be guaranteed at the time of the re-engagement, and a shock occurs, FIG. As shown by the dashed line, the end of the shift control or the engine torque control for the relative rotation difference 0 is preferably delayed after the low clutch 31 is re-engaged.

In any of the above embodiments, the neutral control during braking ends when the accelerator pedal is depressed after the braking release instant t2, as shown in FIG. 4 or FIG. Needless to say, the neutral control during braking may be immediately terminated at the braking release instant t2.

In the above description, the case where the continuously variable transmission is the toroidal type continuously variable transmission 2 has been described. However, the present invention is applied to the case where the continuously variable transmission is a V-belt type continuously variable transmission. It is needless to say that the same operation and effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a power transmission path of a transmission with an infinite speed ratio having a speed change control device during braking according to an embodiment of the present invention, and a speed change control system thereof.

FIG. 2 is a flowchart illustrating a main routine of a braking shift control program executed by a controller in the shift control device.

FIG. 3 is a flowchart showing a subroutine relating to a shift control for controlling a relative rotation difference of a low clutch to zero in the braking shift control program.

FIG. 4 is an operation time chart showing a shift control operation during braking according to the embodiment.

FIG. 5 is a flowchart illustrating a subroutine relating to engine torque control for controlling a relative rotation difference of a low clutch to zero in a braking shift control device according to another embodiment of the present invention.

FIG. 6 is an operation time chart showing a shift control operation during braking according to the embodiment.

FIG. 7 is a speed change diagram illustrating a speed change pattern of an infinite speed ratio transmission.

FIG. 8 is a diagram illustrating a relationship between the speed ratio of the infinite speed ratio transmission and the speed ratio of the toroidal-type continuously variable transmission.

FIG. 9 is a schematic diagram schematically showing a power transmission path of a conventional transmission with an infinite transmission ratio.

[Explanation of symbols]

 ENG engine (motor) 1 input shaft 2 toroidal type continuously variable transmission 3 output shaft 4 planetary gear set 5 toroidal transmission unit 6 toroidal transmission unit 7 input disk 8 output disk 9 power roller 10 flywheel 11 pivot shaft 12 sprocket 21 control valve Body 22 Step motor 23 Hydraulic servo system 24 Low clutch solenoid 25 High clutch solenoid 31 Low clutch for power circulation 32 Sprocket 33 High clutch for direct connection to continuously variable transmission 34 Chain 35 Reduction gear set 36 Final drive gear set 37 Differential gear device 38 Drive Wheel 41 Controller 42 Transmission input rotation sensor 43 Transmission output rotation sensor 44 CVT output rotation sensor 45 Throttle opening sensor 46 Engine rotation sensor 47 Brake switch 48 Idle switch

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Claims (4)

[Claims] A low-speed gear ratio including an infinite gear ratio, which is lower than a certain gear ratio, can be realized by the cooperation of the continuously variable transmission and the planetary gear set when the power-circulating low clutch is engaged. When the high clutch for directly linking a continuously variable transmission is engaged, a speed ratio higher than the certain speed ratio can be realized only by the continuously variable transmission, and the low clutch for power circulation and the high clutch for directly connecting a continuously variable transmission can be realized. In a transmission with an infinite transmission ratio in which a power transmission is not performed when the clutch is disengaged and a power transmission is not performed. A shift control device for braking a transmission with an infinitely variable gear ratio, wherein the engagement of the low clutch for power circulation is prohibited even when the range shifts to a range. 2. The infinite speed change ratio according to claim 1, wherein the prohibition of engagement of the low clutch for power circulation is released when the motor is put into a load state after the release of the braking state. Speed change control device during braking of high speed gear. 3. The speed change control of the continuously variable transmission according to claim 1, wherein while the engagement of the power circulation low clutch is prohibited, the rotation difference between the input / output rotation members of the power circulation low clutch is eliminated. A shift control device during braking of an infinitely variable transmission ratio transmission having the above-mentioned configuration. 4. The motor according to claim 1, wherein the output of the prime mover is controlled such that a rotation difference between the input / output rotary members of the power circulation low clutch is eliminated while the engagement of the power circulation low clutch is prohibited. A shift control device during braking of an infinitely variable transmission ratio transmission.