JP2002054731A - Transmission control device of continuously variable transmission with infinite change gear ratio - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission control device of a continuously variable transmission with an infinite change gear ratio capable of surely preventing stalling even if the change gear ratio does not reach GNP when a grip suddenly recovers after the occurrence of slipping of a driving wheel at the starting. SOLUTION: In the transmission control device of the continuously variable transmission with infinite the change gear ratio, a first solving means is to provide a first torque transmission cut-off control means for outputting a command for releasing a power circulating mode clutch to a clutch pressure control means when a driving wheel slip is detected, and a second solving means is to provide a second torque transmission cut-off control means for outputting a command for making zero differential pressure of both members of a servo piston part to the pressure control means when a driving wheel slip is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuously variable transmission (hereinafter referred to as IVT: Infi.
nitely VariableTransmission), and more particularly, to a control technical field for preventing engine stall (hereinafter abbreviated as engine stall) when the grip of the drive wheel recovers from the drive wheel slip state.

[0002]

2. Description of the Related Art Conventionally, as a shift control device for a continuously variable transmission, Japanese Patent Application Laid-Open No. 9-217801 and Japanese Patent Application Laid-Open No.
No. 071 is known.

[0003] Japanese Patent Application Laid-Open No. Hei 9-217801 discloses that
Aiming at avoiding a sudden shift occurring when the drive wheel spins and a slip and a shift shock of the continuously variable transmission associated therewith, a spin detecting means for detecting idling of the drive wheel is provided. A technique for prohibiting control (upshift) of the vehicle is described.

Japanese Patent Application Laid-Open No. 11-94071 discloses that
Stop at the high speed side gear ratio due to the occurrence of wheel spin,
In order to prevent the vehicle from being unable to restart, a technique is described in which when a wheel spin is detected after a start operation, the high speed side gear ratio is limited to a set gear ratio.

[0005]

SUMMARY OF THE INVENTION However, IVT
When the above-described conventional control is applied to the (speed ratio infinitely variable transmission), when the vehicle speed is low when the drive wheel slip is detected and the grip is suddenly recovered, the gear ratio control alone cannot cope. There is a problem that when the driving wheel recovers the grip, it stalls.

That is, in a vehicle with a torque converter, a drive wheel slip occurs at the time of start, and thereafter, the grip of the drive wheel is suddenly recovered on a dry road at a low vehicle speed,
Even when the drive wheels tend to lock, the occurrence of engine stall can be prevented because the torque converter is interposed.

However, in an IVT vehicle that does not use a torque converter, the power transmission path from the engine to the drive wheels is mechanically coupled, so that the above-described drive wheels tend to lock. Tends to cause an engine stall that causes the engine to stop. In order to prevent this engine stall, the engine stall can be prevented by setting the gear ratio to a geared neutral point (GNP). However, in order to set the gear ratio to GNP after the grip of the drive wheels is recovered, a predetermined gear ratio is required. Since it takes time, the engine stalls during this time and is not a solution to the problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the gear ratio to GNP when the grip suddenly recovers after a slip of the driving wheels at the time of starting or the like. SUMMARY OF THE INVENTION It is an object of the present invention to provide a shift control device for a continuously variable transmission with an infinite gear ratio, which can reliably prevent engine stall even if the speed does not change.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a CVT capable of continuously changing a speed ratio is provided between a CVT and an input / output shaft of the CVT. A planetary gear mechanism, a power circulation mode clutch capable of realizing a power circulation mode in which power is transmitted in a speed ratio range including an infinite gear ratio by engaging the clutch, and a direct connection mode in which power is transmitted only by the CVT by engaging the clutch. An IVT comprising a CVT direct-coupled mode clutch which can be realized; a clutch pressure control means for controlling a clutch pressure of the power circulation mode clutch; and a speed ratio servo control means for controlling a speed ratio of the CVT. In a shift control device for a continuously variable transmission with an infinite speed ratio, a drive wheel slip detecting means for detecting a drive wheel slip, A command to release the circulation mode clutch, characterized in that a first torque transmission interruption control means for outputting to said clutch pressure control means.

According to a second aspect of the present invention, in the transmission control device for an infinitely variable speed ratio transmission according to the first aspect, the first torque transmission cutoff control means is provided in a power circulation mode when a drive wheel slip is detected. A means for outputting a command for controlling a clutch pressure to a pressure equivalent to a clutch return spring to the clutch pressure control means is provided.

According to a third aspect of the present invention, in the speed change control device for an infinitely variable speed ratio transmission according to the second aspect, the first torque transmission cutoff control means is provided in a power circulation mode when a drive wheel slip is detected. A command for controlling the clutch pressure to the clutch return spring equivalent pressure is output to the clutch pressure control means, and while the power circulation mode clutch pressure is controlled to the clutch return spring equivalent pressure, the relative rotation difference of the power circulation mode clutch is reduced. A means for outputting a CVT speed change command to be zero to the speed ratio servo control means is provided.

According to a fourth aspect of the present invention, in the speed change control device for an infinitely variable speed ratio transmission according to the second aspect, the first torque transmission cut-off control means is provided in a power circulation mode when a drive wheel slip is detected. A command for controlling the clutch pressure to the clutch return spring equivalent pressure is output to the clutch pressure control means, and the power circulation mode clutch pressure is set to the clutch return spring equivalent pressure, and then the relative rotation difference of the power circulation mode clutch is set to zero. A means for outputting a CVT speed change command to the speed ratio servo control means is provided.

According to a fifth aspect of the present invention, in the control device for an infinitely variable speed ratio transmission according to the fourth aspect, an oil temperature detecting means for detecting a transmission oil temperature is provided, and the first torque transmission cutoff control is performed. Means are set such that the time from the time when the power circulation mode clutch pressure is set to the pressure equivalent to the clutch return spring to the time when control for starting the relative rotation difference of the power circulation mode clutch is started to be longer as the oil temperature is lower. It is characterized by the following.

According to the sixth aspect of the present invention, the CVT capable of continuously changing the speed ratio, the planetary gear mechanism interposed between the input and output shafts of the CVT, and the speed ratio infinity are established by engaging the clutch. IVT comprising a power circulation mode clutch capable of realizing a power circulation mode for transmitting power in a gear ratio range including the power transmission mode clutch, and a CVT direct connection mode clutch capable of realizing a direct connection mode for transmitting power only by CVT by engaging the clutch. And a pressure control means for controlling a differential pressure between a servo piston portion having a high-side oil chamber and a low-side oil chamber in accordance with a torque to be transmitted to the CVT. In the control device, a drive wheel slip detecting means for detecting a drive wheel slip, and a command to make a differential pressure between both oil chambers of the servo piston portion zero when the drive wheel slip is detected. Second outputting to the serial pressure control means
A torque transmission cutoff control means is provided.

[0015]

According to the first aspect of the present invention, in the first torque transmission cutoff control means, when the drive wheel slip detection means detects the drive wheel slip, the command to release the power circulation mode clutch is issued by the clutch pressure. Output to control means.

That is, before the detection of the driving wheel slip, the power circulation mode in which the power is transmitted in the speed ratio range including the infinite speed ratio is realized by engaging the power circulation mode clutch, but the driving wheel slip is detected. Then, the power circulation mode clutch is set to the released state in which the power transmission between the engine and the drive wheels is cut off.

Therefore, when the grip is suddenly restored after the occurrence of the slip of the drive wheel at the time of starting or the like, the IVT speed ratio becomes G
The engine stall can be surely prevented even if it is not NP.

According to the second aspect of the present invention, the first torque transmission cutoff control means controls the power circulation mode clutch pressure to the pressure equivalent to the clutch return spring when the drive wheel slip detection means detects the drive wheel slip. Is output to the clutch pressure control means.

Here, the clutch return spring equivalent pressure means a critical pressure for generating or not generating the engaging force of the power circulation mode clutch.

Therefore, by shutting off the transmission of torque to the engine when the grip of the drive wheel is restored, engine stall can be reliably prevented. A clutch fastening force can be obtained.

According to the third aspect of the present invention, the first torque transmission cutoff control means detects when a drive wheel slip is detected.
A command for controlling the power circulation mode clutch pressure to the clutch return spring equivalent pressure is output to the clutch pressure control means, and while the power circulation mode clutch pressure is controlled to the clutch return spring equivalent pressure, the relative position of the power circulation mode clutch is controlled. A CVT shift command for setting the rotation difference to zero is output to the speed ratio servo control means.

Therefore, during the control for releasing the power circulation mode clutch, since the relative rotation difference of the power circulation mode clutch is controlled to be zero, after the drive wheel slip is converged, Even if the power circulation mode clutch is engaged, it is possible to prevent a shock due to the clutch engagement.

According to a fourth aspect of the present invention, in the first torque transmission cut-off control means, when a drive wheel slip is detected, a command for controlling the power circulation mode clutch pressure to a clutch return spring equivalent pressure is issued by the clutch pressure control means. After the power circulation mode clutch pressure is set to the pressure equivalent to the clutch return spring, a CVT shift command to make the relative rotation difference of the power circulation mode clutch zero is output to the speed ratio servo control means.

Therefore, after the power circulation mode clutch is released, the relative rotation difference of the power circulation mode clutch is controlled to be zero. Therefore, before the power circulation mode clutch pressure decreases, the relative rotation difference of the clutch is reduced to zero. , The discomfort given to the occupant due to the change in the gear ratio caused by starting the control can be prevented. Of course, similarly to the invention according to the third aspect, even if the power circulation mode clutch is engaged after the drive wheel slip has converged, a shock due to clutch engagement can be prevented.

According to a fifth aspect of the present invention, in the first torque transmission cutoff control means, the relative rotation difference of the power circulation mode clutch is set to zero from the time when the power circulation mode clutch pressure is set to the pressure equivalent to the clutch return spring. The time until the start of the control to be performed is set to be longer as the detected oil temperature is lower.

Therefore, in addition to the operation and effect of the fourth aspect of the invention, the responsiveness of the hydraulic pressure can be further considered, so that the occupant does not have to feel uncomfortable.

According to a sixth aspect of the present invention, the drive wheel slip detecting means detects the drive wheel slip, and the second torque transmission cutoff control means detects the drive wheel slip when both oils of the servo piston portion are detected. A command to make the differential pressure of the chamber zero is output to the pressure control means.

That is, when the drive side torque is controlled by pressure control, the differential pressure of the servo piston portion is CV
When the passing torque to be transmitted to T is zero, the pressure is controlled according to the passing torque to be transmitted to the CVT such that the differential pressure is zero.

Therefore, when the slip of the drive wheel is detected, the pressure difference between the two oil chambers of the servo piston portion is made zero, so that the torque passing through the CVT becomes zero. When the grip is restored, engine stall can be reliably prevented even if the IVT gear ratio is not at GNP.

[0030]

(Embodiment 1) This embodiment 1 is an example corresponding to claims 1, 2 and 3 in which the engine stall is prevented by a torque transmission cutoff method using a clutch.
The configuration will be described.

FIG. 1 is an overall configuration diagram showing a continuously variable transmission with an infinite speed ratio. Between the IVT input shaft 1 connected to the engine and the IVT output shaft 2 connected to the drive wheels, a double-cavity toroidal-type continuously variable transmission mechanism 4 (hereinafter, referred to as a toroidal CVT4) constituted by a half toroid.
, A constant transmission 5 (constant reduction gear), and a single planetary planetary gear mechanism 6. Note that the I
Differential 3 between VT output shaft 2 and drive wheels
Is interposed.

The toroidal CVT 4 has two sets of input discs 41, 41 connected to the input shaft 1 and two sets of output discs 43, 43 connected to the output belt mechanism 42.
And two power rollers 44, 44 sandwiched between the input / output disks 41, 43, respectively. The power rollers 44, 44 each have a trunnion 4
5, 45 (see FIG. 2), and by slightly displacing the trunnions 45, 45 in the direction of the tilting axis, a tilting force is applied to the power rollers 44, 44, and the tilting according to the control command is performed. The CVT speed ratio determined by the tilt angle of the power rollers 44, 44 is steplessly changed.

The constant transmission 5 is provided with an input gear 51 fixed to the IVT input shaft 1 and meshes with the input gear 51 while the IVT is being driven.
The output gear 52 is rotatably supported on the output shaft 2 and includes a reduction gear mechanism.

The planetary gear mechanism 6 includes a sun gear 61 rotatably supported on the IVT output shaft 2, a pinion carrier 62 supporting a pinion, and a ring gear 63 fixed to the IVT output shaft 2. I have.

The pinion carrier 6 of the planetary gear mechanism 6
A power circulation mode clutch 8 is disposed between the CVT 2 and the output gear 52 of the constant transmission 5, and a CVT direct connection mode clutch 9 is disposed between the output belt mechanism 42 of the toroidal CVT 4 and the IVT output shaft 2. .

The transmission torque of the power circulation mode clutch 8 is controlled by using the solenoid pressure from the low clutch solenoid valve 21 (normally closed duty solenoid valve structure) and the feedback pressure as the operation signal pressure, and the line pressure P
Low clutch control valve 15 based on L
(Spool valve structure).

Transmission torque control of the CVT direct-coupled mode clutch 9 is performed by using the solenoid pressure from the high clutch solenoid valve 22 (normally closed duty solenoid valve structure) and the feedback pressure as an operation signal pressure, and using the line pressure PL as a base pressure. High clutch control valve 16
(Spool valve structure). Note that the clutch pressure characteristic is determined by the solenoid valve 2
This shows a characteristic in which the clutch pressure increases in proportion to the duty ratio of the duty command value for 1 and 22.

A CVT input rotation sensor 10 is disposed at a position close to the teeth of the input gear 51 of the constant transmission 5, and a CVT output rotation sensor 11 is positioned at a position close to the output belt mechanism 42 of the toroidal CVT 4. Placed,
An output rotation sensor 12 (vehicle speed sensor) is provided at a position near a tooth portion of a sensor gear 13 provided on the IVT output shaft 2.
Is arranged.

FIG. 2 is a mechanical configuration diagram of a hydraulic system for managing the shift of the IVT. The power roller 44 is a trunnion 45
Is supported from the back. The speed change in the toroidal CVT 4 is performed by displacing the trunnion 45 up and down from the equilibrium point, and this displacement causes a difference in the rotation direction vector between the power roller 44 and the input / output disks 41 and 43, and the power roller 44 tilts. I do.

The trunnion 45 is connected to the servo piston 31 of the hydraulic servo 30, and
In the Hi-side cylinder 30a and the Low-side cylinder 3
It is displaced by the differential pressure of the oil pressure within 0b. Hi side cylinder 30a
And the hydraulic pressure of the low side cylinder 30b are controlled by the shift control valve 46.

A precess cam 35 is attached to one of the trunnions 45.
5 is grooved. The groove of the precess cam 35 is in contact with one end of the L link 38, and one end of the L link 38 is freely supported by one end of the I link 37. Therefore, the displacement and the tilt angle of the trunnion 45 are fed back to the I-link 37. The other end of the I-link 37 is a step motor 3
The spool 46S of the shift control valve 46 is freely supported on the I-link 37. Therefore, the spool 46S is determined based on the displacement of the step motor 36 and the feedback from the precess cam 35.
Is determined.

The hydraulic circuit for generating the supply pressure to the hydraulic servo 30 includes a directional flow control for controlling the speed ratio of the toroidal CVT 4 and a pressure control for controlling the passing torque of the toroidal CVT 4. A circuit based on a control serial system is employed (corresponding to the speed ratio servo control means of claim 1 and the pressure control means of claim 6).

The shift control valve 46 has a spool 46S whose one end is freely supported on an I-link 37.
And a Hi-side cylinder pressure port 4 formed in a spool hole.
6Hi, Low side cylinder pressure port 46Lo, line pressure port 46L, Hi side drain pressure port 46Hid, and Low side drain pressure port 46Lod.

The Hi-side cylinder pressure port 46Hi is
The low-side cylinder pressure port 46Lo is connected to the low-side cylinder 30b of the hydraulic servo 30 via the low-side cylinder pressure oil passage through the i-side cylinder pressure oil passage and the low-side cylinder pressure port 46Lo. , The line pressure port 46L is communicated with a line pressure oil passage,
The i-side drain pressure port 46Hid is connected to the Hi-side drain pressure oil passage, and is connected to the low-side drain pressure port 46Lod.
Is connected to a Low side drain pressure oil passage.

The line pressure P applied to the line pressure port 46L
L is a pressure regulator valve 14 (a spool valve structure) that uses a solenoid pressure from a line pressure solenoid valve 23 (a normally open duty solenoid valve structure) and a feedback pressure as an operation signal pressure, and uses a pump pressure PO / P as a base pressure. ).

The Hi-side drain pressure PHid to the Hi-side drain pressure port 46Hid operates the solenoid pressure from the Hi-side drain pressure solenoid valve 26 (normally closed duty solenoid valve structure), the feedback pressure, and the line pressure PL. The signal pressure is generated by a Hi-side drain pressure control valve 17 (spool valve structure) having a line pressure PL as a base pressure.

The low-side drain pressure PLod to the low-side drain pressure port 46Lod is determined by the solenoid pressure from the low-side drain pressure solenoid valve 27 (normally closed duty solenoid valve structure), the feedback pressure,
It is generated by a low-side drain pressure control valve 18 (spool valve structure) using the line pressure PL as an operation signal pressure and the line pressure PL as a base pressure.

At the time of the directional flow control, the Low side drain pressure PLod is controlled so as to secure the differential pressure more than necessary. Also, at the time of pressure control in which the drive side torque is controlled by pressure control, an instruction for increasing the IVT from the actual gear ratio is sent to the step motor 36 (low side of the CVT in the power circulation mode), and the differential pressure is applied to the toroidal CVT 4. Control is performed according to the passing torque to be transmitted.

FIG. 3 is a diagram showing an IVT electronic control system.
An IVT controller 20 that outputs a control command based on input information; and an IVT unit 19, in which a step motor 36 as a shift control actuator that operates a trunnion 45 that supports the power roller 44; A low clutch solenoid valve 21, a high clutch solenoid valve 22, a Hi side drain pressure solenoid valve 26, a Low side drain pressure solenoid valve 27, a line pressure solenoid valve 23, and an oil temperature sensor 24 are provided.

The IVT controller 20 receives a range signal from an inhibitor switch (not shown) and the CVT
A CVT input rotation signal from the input rotation sensor 10, a CVT output rotation signal from the CVT output rotation sensor 11, and an output shaft rotation (vehicle speed) from the output rotation sensor 12.
Signal, a throttle opening signal from a throttle opening sensor (not shown), and idle S from an idle switch (not shown).
W signal and brake SW from brake switch (not shown)
A signal, an oil temperature sensor signal from the oil temperature sensor 24, other signals, and information on the target idle speed and the idle control flag from the engine controller 25 are input.

In the IVT controller 20, a power circulation mode in which the power is transmitted including GNP having an infinite IVT gear ratio by engaging the power circulation mode clutch 8;
VT direct connection mode Toroidal CV
A clutch switching control is performed to switch a CVT direct coupling mode (= power direct coupling mode) for transmitting power according to the output of T4 at a rotation synchronization point (RSP; also referred to as a mode switching point) at which the IVT speed ratio matches.

Further, a target IVT input speed determined by the vehicle speed and the throttle opening and a detected output speed (actual IV speed)
The target IVT speed ratio is determined by the (T output speed), and the speed ratio control for controlling the speed ratio of the toroidal CVT 4 so as to achieve the target IVT speed ratio is performed by the directional flow control.

Further, the toroidal CVT is controlled by GNP control or the like.
When it is desired to manage the passing torque of No. 4, the differential pressure control for controlling the differential pressure of the hydraulic servo 30 is implemented by the above-described pressure control so as to realize the torque.

Next, the IVT speed ratio characteristics shown in FIG. 4 (the vertical axis is 1 / IVT speed ratio = output shaft speed / input shaft speed, and the horizontal axis is CVT speed ratio) will be described.

In the case of the power circulation mode, the pinion carrier 62 of the planetary gear mechanism 6 rotates at a constant rotational speed whose IVT input rotational speed is reduced by the constant transmission 5 by the engagement of the power circulation mode clutch 8, and the sun gear 61 changes the CVT speed. The rotation speed changes according to the change in the ratio, and the rotation of the ring gear 63 becomes the output shaft rotation of the continuously variable transmission with an infinite speed ratio. Therefore,
As shown in FIG. 4, in the power circulation mode, the output shaft rotation of the IVT changes from backward to neutral to forward according to the change in the CVT speed ratio from high to low.

In the case of the CVT direct connection mode, the pinion carrier 62 of the planetary gear mechanism 6 can rotate freely by releasing the power circulation mode clutch 8, and the ring gear 63
The VT direct coupling mode clutch 9 is coupled to the sun gear 61 by being engaged, and rotates at the same rotational speed. Therefore, as shown in FIG. 4, in the CVT direct connection mode, the IVT speed ratio changes from low to high in the forward direction in accordance with the change in the CVT speed ratio from low to high.

Next, the operation will be described.

[Slip torque transmission cutoff control processing]
FIG. 5 is a flowchart showing a flow of a torque transmission cutoff control process by the clutch at the time of slip performed by the IVT controller 20, and each step will be described below.

In step 401, a driving wheel slip is detected (driving wheel slip detecting means). This drive wheel slip may be performed by the rotation difference between the drive wheel and the driven wheel, may be performed by the change rate of the input shaft rotation speed, or may be performed by the input / output shaft rotation ratio (speed ratio). Is also good.

In step 402, it is determined whether or not a drive wheel slip has occurred based on whether or not the detected drive wheel slip value is equal to or greater than a set threshold value.

If YES is determined in the step 402, the process proceeds to a step 403, where the flag is set to 1 (indicating that the driving wheel is slipping).

In step 404, the power circulation mode clutch pressure is controlled to a return spring equivalent pressure. In addition,
The return spring equivalent pressure means a critical pressure at which the engagement force of the power circulation mode clutch 8 is generated or not.

In step 405, the step motor 36 is controlled so that the relative rotation speed difference of the power circulation mode clutch 8 becomes zero.

On the other hand, if NO is determined in the step 402, the process proceeds to a step 406.
It is determined whether the flag is 1 or not. If the flag is 1, the process proceeds to step 407, and if the flag is 0, the process directly proceeds to step 410.

In step 407, the input shaft rotation speed is detected by the CVT input rotation sensor 10.

In step 408, it is determined whether or not the input shaft rotation speed detected in step 407 is synchronized with the rotation synchronization input rotation speed of the clutch unit. If NO, the flow returns to step 407 to determine the rotation speed synchronization. The process is repeated, and if it is determined in step 408 that the input shaft rotation speeds are synchronized, the process proceeds to step 409, and the flag is rewritten from 1 to 0.

In step 410, the clutch pressure of the power circulation mode clutch 8 is controlled to a pressure that can maintain a state where there is no relative rotation difference (completely engaged state). This pressure is
It may be calculated from the engine output torque and the gear ratio,
The maximum pressure may be used.

In step 411, a target gear ratio is calculated based on the normal throttle opening TVO and the vehicle speed Vs, and the step motor 36 is controlled so as to realize the target gear ratio.

FIG. 6 shows a time chart when the above control processing is performed. First, from the actual slip start time t0 to the slip detection time t1, the clutch pressure of the power circulation mode clutch 8 is kept at the engagement pressure. The CVT gear ratio changes by controlling the number of steps based on the throttle opening TVO and the vehicle speed Vs.

Next, from the slip detection time t1 to the clutch part rotation synchronization time t3, the power circulation mode clutch 8
Is reduced to the clutch return spring equivalent pressure, and the CVT speed ratio is controlled by the number of steps so that the rotation difference between the input and output days of the power circulation mode clutch 8 becomes zero.

Since there is no clutch engagement force of the power circulation mode clutch 8 from the slip detection time t1 to the clutch portion rotation synchronization time t3, the servo piston differential pressure ΔP basically becomes zero. , A slight pressure difference ΔP is generated. Further, the input shaft speed is highest at the actual slip end time t2, and the clutch unit rotation synchronization time t3 is reached from the actual slip end time t2.
Up to this point, the CVT ratio is shifted down in the downshift direction (the IVT ratio is upshifted) by the control of the step motor 36 to reduce the input shaft speed to the synchronous speed.

At the time point t3 when the rotation of the clutch unit is synchronized, a command is issued to set the clutch pressure of the power circulation mode clutch 8 to a non-slip engagement pressure, and the CVT speed ratio is set based on the throttle opening TVO and the vehicle speed Vs. Ratio is calculated, and the stepping motor 3 is driven to achieve the target gear ratio.
6 is returned to the normal step number control.

Next, the effects will be described. (1) When the drive wheel slip is detected, the power circulation mode clutch 8 is set to the released state in which the power transmission between the engine and the drive wheel is cut off. When the grip is restored, the IVT gear ratio becomes G
The engine stall can be surely prevented even if it is not NP. (2) When a drive wheel slip is detected, the power circulation mode clutch pressure is controlled to the pressure equivalent to the clutch return spring. And the power circulation mode clutch 8
, The clutch engagement force can be obtained with good response. (3) When the drive wheel slip is detected, the power circulation mode clutch pressure is controlled to the clutch return spring equivalent pressure and the power circulation mode clutch 8 is controlled while the power circulation mode clutch pressure is controlled to the clutch return spring equivalent pressure. Since the CVT shift control that makes the relative rotation difference zero is performed, even if the power circulation mode clutch 8 is engaged after the drive wheel slip has converged, a shock due to clutch engagement can be prevented.

In the first embodiment, an example is shown in which CVT shift control is performed in which the relative rotation difference of the power circulation mode clutch 8 is made zero while the power circulation mode clutch pressure is controlled to the pressure equivalent to the clutch return spring. However, when the drive wheel slip is detected, the power circulation mode clutch pressure is controlled to the clutch return spring equivalent pressure, the power circulation mode clutch pressure is set to the clutch return spring equivalent pressure, and then the relative rotation difference of the power circulation mode clutch 8 is reduced to zero. (Claim 4).
In this case, it is possible to prevent the occupant from feeling uncomfortable due to a change in the gear ratio caused by starting the control for reducing the relative rotation difference of the clutch before the clutch pressure in the power circulation mode decreases.

The waiting time from the time when the power circulation mode clutch pressure is set to the pressure equivalent to the clutch return spring to the time when the control for making the relative rotation difference of the power circulation mode clutch zero is started is determined by the time when the detected oil temperature is low. An example in which the time is set as long as possible may be adopted (claim 5). In this case, the responsiveness of the hydraulic pressure can be further considered, so that the occupant does not have to feel uncomfortable.

Further, in the first embodiment, an example has been described in which the rotation of the clutch portion is synchronized by the speed ratio control by the step motor 36. However, the speed ratio control and the method of temporarily lowering the engine torque are described. May be used together.

(Embodiment 2) Next, Embodiment 2 will be described. The second embodiment is an example corresponding to claim 6 in which the engine stall prevention is performed by a torque transmission cutoff system using a differential pressure.
Since the configuration is the same as that described above, illustration and description are omitted.

Next, the operation will be described.

[Slip torque transmission cutoff control processing]
FIG. 7 is a flowchart showing the flow of the torque transmission cutoff control process by the differential pressure at the time of slip performed by the IVT controller 20, and each step will be described below.

In step 501, similarly to step 401, a drive wheel slip is detected (drive wheel slip detecting means).

In step 502, as in step 402, it is determined whether or not a drive wheel slip has occurred based on whether or not the detected drive wheel slip value is equal to or greater than a set threshold value.

If YES is determined in step 502, the process proceeds to step 503, and in step 503, the flag is set to 1 (indicating that the driving wheel is slipping).

In step 504, the Hi-side cylinder 30
The hydraulic pressure PHi in a is set to the line pressure PL, the hydraulic pressure PLo in the low side cylinder 30b is set to the line pressure PL, and the servo piston differential pressure ΔP, which is the hydraulic pressure difference between the two cylinders, is controlled to zero. That is, the drain pressure is reduced to the line pressure PL by turning off the solenoid valves 26 and 27.
So that the Hi-side cylinder pressure PHi is
The L, Low side cylinder pressure PLo also becomes the line pressure PL.

In step 505, the throttle opening TV
The gear ratio feedback control for the step motor 36 is performed so that the gear ratio is based on O and the vehicle speed Vs.

On the other hand, if NO is determined in step 502, the process proceeds to step 506, and in step 506,
It is determined whether or not the flag is 1. When the flag is 1, the flag is set to 0 in step 507, and when the flag is 0, the process directly proceeds to step 508.

At step 508, the Hi-side cylinder pressure P
The solenoid valves 26 and 27 are energized so that Hi becomes a drain and Low-side cylinder pressure PLo becomes a drain, and the pressure control for reducing the servo piston differential pressure ΔP to zero is released.

At step 509, the throttle opening TV
The gear ratio feedback control for the step motor 36 is performed so that the gear ratio is based on O and the vehicle speed Vs.

FIG. 8 shows a time chart when the above control processing is performed. First, from the actual slip start time t0 to the slip detection time t1
Until then, the clutch pressure of the power circulation mode clutch 8 is kept at the engagement pressure. The CVT gear ratio changes by controlling the number of steps based on the throttle opening TVO and the vehicle speed Vs.

Next, from the slip detection time t1 to the actual slip end time t2, the clutch pressure of the power circulation mode clutch 8 is maintained at the engagement pressure, and the servo piston differential pressure △
Pressure control for making P zero is performed.

The actual slip end time t at which the grip recovers
When the pressure becomes 2, the pressure control for reducing the servo piston differential pressure ΔP to zero is released, and the step number control for controlling the step motor 36 so as to obtain a gear ratio based on the throttle opening TVO and the vehicle speed Vs is performed, and the IVT is performed. The gear is shifted in a direction where the gear ratio becomes geared neutral.

Although the number of steps increases from the slip detection time t1 to the actual slip end time t2 in the step number characteristic of FIG. 8 and the CVT ratio changes, this pressure control is performed. In the interval, CV by step number control
There is no change in the T speed ratio, and the CVT speed ratio changes so that the passing torque of the toroidal CVT becomes zero.

[Pressure Control] Now, the pressure control method will be described with reference to a basic configuration diagram shown in FIG.
The force F acting on the power roller at the point of contact with the input disk is F = Ti / (Ri · n1 · n2), and the force F acting on the power roller at the point of contact with the output disk is F = To / (Ro · n1 · n2). When balanced, ΔP = PHi−PLo = 2 · Ti / (S · Ri · n1 · n2) = 2 · To / (S · Ro · n1 · n2) Therefore, the passing torque of the toroidal CVT can be made zero by setting the servo piston differential pressure ΔP to zero. Further, by controlling the servo piston differential pressure ΔP, the passing torque of the toroidal CVT can be changed. That is, the servo piston differential pressure △ P
, The speed changes rapidly due to the occurrence of Y displacement (the amount of displacement between the rotation axis of the power roller and the disk rotation axis), and the torque approaches the toroidal CVT passing torque corresponding to the magnitude of the servo piston differential pressure ΔP.

Next, the effects will be described.

In the second embodiment, the differential pressure ΔP between the two cylinders 30a and 30b of the hydraulic servo 30 is kept at zero when the driving wheel slip is detected, so that the torque passing through the toroidal CVT becomes zero and the vehicle starts. When the grip suddenly recovers after the occurrence of a slip of the drive wheels, for example, the engine stall is reliably prevented without releasing the power circulation mode clutch 8 even if the IVT gear ratio is not at GNP. can do.

In the second embodiment, the line pressure P
The example in which the servo piston differential pressure ΔP is made zero by adding L has been described.
It is not always the line pressure PL.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an example of a continuously variable transmission with an infinite gear ratio to which a shift control device according to a first embodiment is applied.

FIG. 2 is a diagram illustrating a hydraulic control system of a toroidal CVT used in the infinitely variable speed ratio transmission according to the first embodiment.

FIG. 3 is a control block diagram illustrating an electronic speed change control system in the continuously variable transmission with an infinite speed ratio according to the first embodiment.

FIG. 4 is a diagram illustrating an IVT speed ratio characteristic of the infinitely variable speed ratio continuously variable transmission according to the first embodiment;

FIG. 5 is a flowchart showing a flow of a torque transmission cutoff control process by the clutch at the time of slip performed by the IVT controller according to the first embodiment;

FIG. 6 is a time chart showing a torque transmission cutoff operation by a clutch during a slip in the first embodiment.

FIG. 7 is a flowchart showing a flow of a torque transmission cutoff control process based on a differential pressure at the time of slip performed by the IVT controller according to the second embodiment.

FIG. 8 is a time chart showing a torque transmission cutoff effect due to a differential pressure at the time of slip in the second embodiment.

FIG. 9 is a basic configuration diagram for explaining a pressure control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 IVT input shaft 2 IVT output shaft 3 Differential 4 Toroidal type continuously variable transmission mechanism 5 Constant transmission 6 Planetary gear mechanism 8 Power circulation mode clutch 9 Direct connection mode clutch 10 CVT input rotation sensor 11 CVT output rotation sensor 12 Output rotation (vehicle speed) Sensor 13 Sensor gear 14 Pressure regulator valve 15 Low clutch control valve 16 High clutch control valve 17 Hi side drain pressure control valve 18 Low side drain pressure control valve 19 IVT unit 20 IVT controller 21 Low clutch solenoid valve 22 High clutch solenoid valve 23 Line Pressure solenoid valve 24 Oil temperature sensor 25 Engine control controller 26 Hi side drain pressure solenoid valve 27 Low side Lane pressure solenoid valve 30 Hydraulic servo 30a Hi side cylinder 30b Low side cylinder 31 Servo piston 35 Precess cam 36 Step motor 37 I link 38 L link 41 Input disk 42 Output belt mechanism 43 Output disk 44 Power roller 45 Trunnion 46 Shift control valve 46S spool 46Hi Hi side cylinder pressure port 46Lo Low side cylinder pressure port 46L Line pressure port 46Hid Hi side drain pressure port 46Lod Low side drain pressure port 51 Input gear 52 Output gear 61 Sun gear 62 Pinion carrier 63 Ring gear

Claims (6)

[Claims] 1. A continuously variable transmission mechanism (hereinafter, referred to as a CVT) capable of continuously changing a speed ratio, a planetary gear mechanism interposed between input and output shafts of the CVT, and a clutch engaged to change a speed. A power circulation mode clutch capable of realizing a power circulation mode for transmitting power in a speed ratio range including an infinite ratio, and a CVT direct connection mode clutch capable of realizing a direct connection mode for transmitting power only by CVT by engaging the clutch. An infinitely variable speed ratio transmission (hereinafter referred to as IVT), clutch pressure control means for controlling the clutch pressure of the power circulation mode clutch, and speed ratio servo control means for controlling the speed ratio of the CVT And a drive wheel slip detecting means for detecting a drive wheel slip; and a drive wheel slip detection. , The shift control device of the IVT, characterized in that a first torque transmission interruption control means for outputting a command to release the power recirculation mode clutch to the clutch pressure control means. 2. The speed change control device for an infinitely variable speed ratio transmission according to claim 1, wherein the first torque transmission cut-off control means controls a power return mode clutch pressure when a drive wheel slip is detected. A shift control device for a continuously variable transmission with an infinite gear ratio, wherein the shift control device outputs a command to control the equivalent pressure to the clutch pressure control unit. 3. The transmission control device for a continuously variable transmission with an infinitely variable gear ratio according to claim 2, wherein the first torque transmission cutoff control means controls a power circulation mode clutch pressure when a drive wheel slip is detected. A CVT shift command that outputs a command to control the equivalent pressure to the clutch pressure control means and sets the relative rotation difference of the power circulation mode clutch to zero while controlling the power circulation mode clutch pressure to the clutch return spring equivalent pressure. A transmission control device for a continuously variable transmission with an infinite transmission ratio, wherein the transmission control device outputs the output to the transmission ratio servo control unit. 4. The transmission control apparatus for an infinitely variable speed ratio continuously variable transmission according to claim 2, wherein the first torque transmission cutoff control means controls a power circulation mode clutch pressure when a drive wheel slip is detected. After outputting a command to control the equivalent pressure to the clutch pressure control means and setting the power circulation mode clutch pressure to a clutch return spring equivalent pressure, the CVT shift command for setting the relative rotation difference of the power circulation mode clutch to zero is transmitted to the gear shift. A transmission control device for a continuously variable transmission with an infinite transmission ratio, characterized in that the transmission is output to a ratio servo control unit. 5. The control device for a continuously variable transmission with an infinite gear ratio according to claim 4, further comprising an oil temperature detecting means for detecting a transmission oil temperature, wherein the first torque transmission cutoff control means is provided in a power circulation mode. A shift from a point in time when the clutch pressure is made equivalent to the clutch return spring to a point in time when control for starting the relative rotation difference of the power circulation mode clutch is started is set to be longer as the oil temperature is lower. Transmission control device for a continuously variable transmission with infinite ratio. 6. A CVT capable of continuously changing a speed ratio, a planetary gear mechanism interposed between input and output shafts of the CVT, and power in a speed ratio range including an infinite speed ratio by engaging a clutch. IVT comprising a power circulation mode clutch capable of realizing a power circulation mode for transmitting power and a CVT direct connection mode clutch capable of realizing a direct connection mode for transmitting power only by CVT by engaging the clutch.
And a pressure control means for controlling a differential pressure between a servo piston portion having a high-side oil chamber and a low-side oil chamber in accordance with a torque to be transmitted to the CVT. In the control device, a drive wheel slip detecting means for detecting a drive wheel slip, and a second torque for outputting to the pressure control means a command to make the differential pressure between both oil chambers of the servo piston portion zero when the drive wheel slip is detected. A transmission control device for a continuously variable transmission with an infinite transmission ratio, comprising transmission interruption control means.