JP2008045607A - Continuously variable transmission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent worsening in heat, fuel consumption or power performance due to erroneous protecting control of a CVT based on erroneous determination, by determining off-road run with high accuracy. <P>SOLUTION: A controller 12 performs first off-road determination to determine the process of off-road run in a first road surface condition in accordance with road surface input high frequency components of a secondary pulley rotating speed Nsec, and performs second off-road determination to determine the process of off-road run in a second road surface condition in which the roughness of a road surface is more severe than in the first road surface condition, in accordance with the input or not of sudden torque from a driving wheel to the CVT 1. When determining the process of off-road run in the first road surface condition from the first off-road determination and determining the process of off-road run from the second off-road determination, the controller 12 executes off-road control to protect the CVT 1 from the sudden torque. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for protecting a continuously variable transmission (hereinafter referred to as “CVT”) when traveling on a rough road.

  In a vehicle that transmits engine rotation to drive wheels via a transmission, torque from the engine is input to the transmission while the vehicle is running, and torque is also input from the drive wheels according to the road surface condition. The When driving on rough roads, the torque input from the drive wheels increases, so when the transmission is a belt type CVT, it is necessary to increase the hydraulic pressure supplied to the pulley to prevent the belt from slipping and to protect the CVT. There is.

In this regard, in the technique described in Patent Document 1, the output rotation speed of the CVT is bandpass filtered, and the obtained value is integrated in a time window. The hydraulic pressure to supply to is increased.
Japanese Patent Laid-Open No. 2003-269591

  By the way, as protection control of CVT, in addition to increasing the hydraulic pressure supplied to the pulley, lowering the engine output, releasing or sliding the lockup clutch, or changing the shift line, the torque itself input to the CVT There is also a method of protecting CVT by reducing the above.

  However, any protection control is disadvantageous in terms of heat, fuel consumption, or power performance. For example, when the hydraulic pressure supplied to the pulley is increased, the fuel consumption is deteriorated and the heat is disadvantageous. The same applies when releasing or sliding the lockup clutch or changing the shift line. Further, when the engine output is lowered, the power performance is lowered.

  Therefore, it is necessary to accurately determine whether or not to perform CVT protection control, that is, whether or not the vehicle is traveling on a rough road.

  The present invention has been made in view of such technical problems, and it is possible to determine bad road traveling with high accuracy and to detect heat, fuel consumption, or power performance due to erroneous CVT protection control based on erroneous determination. The purpose is to prevent deterioration.

  The present invention is used in a control device for a continuously variable transmission that continuously changes the output rotation of an engine and transmits it to drive wheels, and controls the belt clamping force of a pair of pulleys that are torque transmission members. The present invention relates to a continuously variable transmission control device that changes the input torque to the torque transmission member by changing the torque capacity of the torque transmission member and controlling the output torque of the engine. First rough road determination means for determining whether the vehicle is traveling on a rough road in the first road surface state based on a high-frequency component by road surface input, and whether or not there is a temporary large sudden torque input from the drive wheel to the transmission Based on the second rough road determination means for determining whether the road surface is rougher than the first road surface condition, and the first rough road determination means 1 bad road condition The continuously variable transmission is protected from the sudden torque when it is determined that the vehicle is traveling and the second rough road determination means determines that the vehicle is traveling on a rough road in the second road surface condition. Off-load control means for executing off-load control for the purpose.

  According to the present invention, the bad road determination is performed twice, and in order to be determined as the bad road traveling in the second road surface state (off-road traveling), it is the rough road traveling in the first road surface state. In addition to this determination, it is necessary to determine that the sudden torque has been input. As a result, the accuracy of determination on off-road driving is improved especially during rough road driving, and the heat, fuel consumption, or fuel consumption caused by erroneous off-road control for protecting the continuously variable transmission in response to erroneous determination. Deterioration of power performance can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification, “good road” refers to a paved road paved with asphalt, concrete, etc., and “the first bad road surface” refers to unpaved roads such as gravel roads and kuriishi roads in general. Point to. “Bad road (off-road) in the second road surface condition” means that, among bad roads, obstacles such as large stones, timber, curbs, etc. and road surface depressions exist in the traveling direction, and the first road surface. The road surface is more uneven than the rough road, and indicates a road surface where sudden torque is input from the drive wheels to the transmission. "Sudden torque" is a sudden large torque that is temporarily input from the drive wheel to the transmission when the vehicle climbs over an obstacle or when the drive wheel that slips after overcoming the obstacle comes into contact with the ground again. Point to.

  FIG. 1 shows a schematic configuration of a belt type continuously variable transmission (hereinafter referred to as “CVT”) 1. A primary pulley 2 and a secondary pulley 3 that are torque transmission members are arranged so that their V grooves are aligned, and a V belt 4 is stretched over the V grooves of these pulleys 2 and 3. An engine 5 is arranged coaxially with the primary pulley 2, and a torque converter 6 having a lock-up clutch 6c and a forward / reverse switching mechanism 7 are provided between the engine 5 and the primary pulley 2 in this order from the engine 5 side. Yes.

  The forward / reverse switching mechanism 7 includes a double pinion planetary gear set 7 a as a main component, and its sun gear is coupled to the engine 5 via the torque converter 6, and the carrier is coupled to the primary pulley 2. The forward / reverse switching mechanism 7 further includes a forward clutch 7b that directly connects the sun gear and the carrier of the double pinion planetary gear set 7a, and a reverse brake 7c that fixes the ring gear. When the forward clutch 7b is engaged, the input rotation from the engine 5 via the torque converter 6 is directly transmitted to the primary pulley 2, and when the reverse brake 7c is engaged, the input rotation via the torque converter 6 from the engine 5 is reversed. Is transmitted to the primary pulley 2.

  The rotation of the primary pulley 2 is transmitted to the secondary pulley 3 via the V-belt 4, and the rotation of the secondary pulley 3 is transmitted to the driving wheel (not shown) via the output shaft 8, the gear set 9 and the differential gear device 10.

  In order to make it possible to change the gear ratio between the primary pulley 2 and the secondary pulley 3 during the power transmission described above, one of the conical plates forming the V grooves of the primary pulley 2 and the secondary pulley 3 is fixed to the fixed conical plates 2a, 3a. The other conical plates 2b and 3b are movable conical plates that can be displaced in the axial direction.

  These movable conical plates 2b and 3b are directed toward the fixed conical plates 2a and 3a by supplying the primary pulley pressure Ppri and the secondary pulley pressure Psec created using the line pressure as the original pressure to the primary pulley chamber 2c and the secondary pulley chamber 3c. As a result, the V-belt 4 is frictionally engaged with the conical plate, and power is transmitted between the primary pulley 2 and the secondary pulley 3.

  At the time of shifting, the width of the V groove of both pulleys 2 and 3 is changed by the differential pressure between the primary pulley pressure Ppri and the secondary pulley pressure Psec generated corresponding to the target gear ratio, and the V belt 4 for the pulleys 2 and 3 is changed. The target gear ratio is realized by continuously changing the wrapping arc diameter.

  The primary pulley pressure Ppri and the secondary pulley pressure Psec are controlled by the shift control hydraulic circuit 11 together with the engagement hydraulic pressure of the forward clutch 7b that is engaged when the forward travel range is selected and the reverse brake 7c that is engaged when the reverse travel range is selected. The shift control hydraulic circuit 11 performs control in response to a signal from the transmission controller 12.

  The transmission controller 12 includes a signal from the primary pulley rotation sensor 13 that detects the rotation speed Npri of the primary pulley 2, a signal from the secondary pulley rotation sensor 14 that detects the rotation speed Nsec of the secondary pulley 3, and a secondary pulley pressure. A signal from the secondary pulley pressure sensor 15 that detects Psec, a signal from the accelerator operation amount sensor 16 that detects the operation amount APO of the accelerator pedal, a selection range signal from the inhibitor switch 17 that detects the position of the select lever, and CVT1 A signal from the oil temperature sensor 18 for detecting the hydraulic oil temperature TMP, a signal related to the input torque Tp from the engine controller 19 for controlling the engine 5 (engine rotation speed and fuel injection time), and the off-road switch 21 ON / OFF signal is input It is. The off-road switch 21 is a switch that is turned off during normal traveling and is manually turned on by the driver when the driver intends off-road traveling.

  The transmission controller 12 extracts a high-frequency component from the road surface input of the output rotational speed of the CVT 1 (in this embodiment, the secondary pulley rotational speed Nsec, the vehicle speed, and the wheel speed may be used), and the magnitude of the high-frequency component. To determine the rough road running in the first road surface condition (first bad road determination). If it is determined by the first rough road determination that the road surface condition is the rough road, a command to increase the secondary pulley pressure Psec to the first pressure P1 is issued to the transmission control hydraulic circuit 11, and the belt 4 The rough road is controlled to prevent slipping.

  According to the increase in the secondary pulley pressure Psec due to this rough road control, the CVT 1 is not completely protected from the sudden torque, but the belt is clamped only enough to protect the CVT 1 against the input of torque smaller than the sudden torque. The force, that is, the torque capacity of the pulley (the maximum torque that can be transmitted) can be obtained.

  When it is determined by the first rough road determination that the road surface is in the first road surface condition, it is possible to perform the second road surface rough road condition (off-road driving) in which the road surface is more uneven than the first road surface condition. There is sex. Therefore, in this case, the rotation deceleration is calculated from the rotation speed Npri of the primary pulley 2 that is the input side rotation speed of the CVT 1 to calculate the deceleration inertia torque. Then, based on the deceleration inertia torque of the primary pulley 2, it is determined whether or not the sudden torque is input from the drive wheel to the CVT 1, and when it is determined that the sudden torque is input, it is determined that the vehicle is off-road driving (second). Bad road judgment). When it is determined that the vehicle is off-road traveling by the second rough road determination, off-road control that further suppresses belt slip is performed.

  In the off-road control, the transmission controller 12 issues a command for increasing the secondary pulley pressure Psec to the second pressure P2 higher than the first pressure P1 to the shift control hydraulic circuit 11 to increase the torque capacity of the pulley. The engine controller 19 issues a command to lower the output torque of the engine 5 (fuel injection amount reduction command, intake air amount reduction command, etc.) to the engine controller 19 so that the input torque to the CVT 1 becomes smaller than the torque capacity of the pulley.

  Due to the increase in the secondary pulley pressure Psec and the decrease in the output torque of the engine 5 due to this off-road control, a belt clamping force is applied to the secondary pulley 3 so that the belt 4 does not slip even if a sudden torque is input, and the torque capacity is increased. In addition, the input torque to the CVT 1 can be reduced, and the CVT 1 can be effectively protected from the sudden torque.

  In this embodiment, a representative example is a method in which the secondary pulley pressure Psec is increased compared to the on-load control that is the normal control in the rough road control, and the output torque of the engine 5 is additionally decreased in the off-road control. As will be described, in addition to the increase in the secondary pulley pressure Psec and the decrease in the output torque of the engine 5, the torque input to the CVT 1 is reduced by releasing or sliding the lock-up clutch 6c or changing the shift line of the CVT 1. By doing so, there is a method for protecting CVT1, and these controls are appropriately performed as necessary.

  On the other hand, when the offload switch 21 is ON, the offload control is performed regardless of the determination, and the CVT 1 is protected.

  2A and 2B are flowcharts showing the contents of CVT protection control performed by the transmission controller 12. The contents of CVT protection control will be described in more detail with reference to this.

  According to this, first, in step S1, a first rough road determination is performed. In this first bad road determination, the bad road running in the first road surface state is determined from the high frequency component due to the road surface input of the secondary pulley rotation speed Nsec, and the bad road running in the first road surface state is judged as bad. When the road travel flag is set to 1 and it is determined that the road is good, the bad road travel flag is set to 0. The first rough road determination is performed according to the flowchart shown in FIG. 3, which will be described later.

  In step S2, it is determined whether the rough road determination flag is 1, and if it is 1, the process proceeds to step S3. If it is 0, the process proceeds to step S8, where the on-road mode is set as the control mode of the transmission controller 12, and the secondary pulley Psec is controlled so as not to slip the belt 4 according to the transmission ratio of the CVT 1 and the input torque. On-load control is executed.

  In step S3, the rough road mode is set as the control mode of the transmission controller 12. The rough road mode is a mode in which the rough road control is executed, and the secondary pulley pressure Psec is increased to the first pressure P1. The first pressure P1 is higher than the secondary pulley Psec set according to the transmission ratio of the CVT 1 and the input torque in the on-road mode.

  In step S4, it is determined whether or not the offload switch 21 is ON. When the off-road switch 21 is ON, the process proceeds to step S9, and the off-road mode is set as the control mode of the transmission controller 12. This off-road mode is a mode in which the off-road control is executed, and the secondary pulley pressure Psec is increased to a second pressure P2 that is higher than the first pressure P1 to increase the torque capacity of the pulley, and The output torque of the engine 5 is reduced so that the input torque to the CVT 1 becomes smaller than the torque capacity of the pulley.

  When the off-road switch 21 is OFF, the process proceeds to step S5 and subsequent steps, and second rough road determination (steps S5 to S7) is performed.

  First, in step S5, the deceleration inertia torque TS of the primary pulley 2 is calculated. Specifically, the deceleration inertia torque TS is calculated by obtaining the rotational deceleration of the rotational speed of the primary pulley 2 that is the input side rotational speed of the CVT 1 and multiplying this by the inertia coefficient. The sign of the rotational deceleration of the primary pulley 2 is such that the deceleration side is positive, the acceleration side is negative, and the deceleration inertia torque TS is calculated as a positive value. When the lock-up clutch 6c is engaged, the inertia corresponding to the engine 5 increases compared to when the lock-up clutch 6c is engaged. Therefore, when the lock-up clutch 6c is engaged, the inertia coefficient includes the lock-up clutch 6c. Set a larger value than when not fastened.

In step S6, the sudden torque threshold value TM is expressed by the following formula:
TM = −1 / k × {Tp−Tt / (ip × if)}
Tp: Input torque from engine 5 side k: Coupling state of lock-up clutch 6c, gear ratio of CVT1, coefficient determined by vehicle drive system (2WD / 4WD) Tt: Road surface input torque that changes according to vehicle speed ip: CVT1 Gear ratio if: Calculated from the gear ratio of the final gear.

  The input torque Tp from the engine 5 side is equal to the torque of the engine 5 when the lock-up clutch 6c is engaged, and can be calculated by referring to a predetermined engine torque map. When the lockup clutch 6c is released, the torque becomes the value obtained by multiplying the torque of the engine 5 by the torque ratio t of the torque converter 6. The sudden torque that can be generated differs depending on the gear ratio, the engagement state of the lock-up clutch 6c, the drive system, and the vehicle speed. Therefore, the sudden torque threshold TM is made variable according to these, so that the occurrence of the sudden torque is accurately determined. can do.

  In step S7, it is determined whether the deceleration inertia torque TS calculated in step S5 exceeds the sudden torque threshold TM calculated in step S6. If not exceeded, the process returns to step S1, and when it is determined again by the first bad road determination that the road condition is the first road surface condition, the rough road mode is set as the control mode of the transmission controller 12, Rough road control is executed (steps S2 and S3).

  On the other hand, if it exceeds the sudden torque threshold TM, it is determined that the vehicle is traveling off-road, and the process proceeds to step S9, where the off-road mode is set as the control mode of the transmission controller 12. In the off-road mode, as described above, the output of the engine 5 is increased so that the secondary pulley pressure Psec is increased to the second pressure P2 to increase the torque capacity of the pulley, and the input torque to the CVT 1 is smaller than the torque capacity of the pulley. Off-road control for reducing torque is executed.

  When the off-road mode is set as the control mode of the transmission controller 12 in step S9, the process proceeds to an off-road mode canceling process after step S10 in FIG. 2B.

  In step S10, the timer T1 is reset to zero. This timer T1 is a timer used for measuring a time interval in which no sudden torque is input.

  In step S11, the deceleration inertia torque TS of the primary pulley 2 is calculated in the same manner as in step S5. In step S12, the sudden torque threshold TM is calculated in the same manner as in step S6.

  In step S13, it is determined whether the deceleration inertia torque TS has exceeded the sudden torque threshold value TM. If so, the process returns to step S10, and the off-road mode set in step S9 is set as the control mode of the transmission controller 12. Maintain and continue offload control.

  If the deceleration inertia torque TS does not exceed the sudden torque threshold value TM, it is determined that there is no new sudden torque input, the process proceeds to step S14, and the timer T1 is increased by ΔT.

  In step S15, it is determined whether or not the timer T1 has exceeded the predetermined time Ta. If the timer T1 has exceeded the predetermined time Ta, the routine proceeds to step S16, assuming that the predetermined time Ta has not been input. If not, the process returns to step S11. Continue to monitor sudden torque. The predetermined time Ta is set to a time during which it can be determined that the off-road driving is finished, and is set to a value of about 10 to 20 seconds, for example.

  In step S16, the first rough road determination is executed as in step S1. As described above, the first rough road determination is performed according to the flowchart shown in FIG. 3, which will be described later.

  In step S17, it is determined whether the rough road determination flag is 1, and if it is 1, the process proceeds to step S18, the off road mode is canceled as the control mode of the transmission controller 12, the rough road mode is set, and the secondary pulley pressure Psec is set. The rough road control for increasing the pressure to the first pressure P1 is executed. On the other hand, if the rough road determination flag is 0, the process proceeds to step S19 to cancel the off-road mode as the control mode of the transmission controller 12 and set the on-road mode, and according to the transmission ratio of the CVT 1 and the input torque. On-load control is performed in which the secondary pulley Psec is controlled to be low enough that the belt does not slip. Thereafter, the process returns to step S1 and the above control is repeatedly executed.

  Next, the contents of the first rough road determination executed in steps S1 and S16 of the flowchart will be described with reference to the flowchart shown in FIG.

  According to this, first, in step S21, it is determined whether the rough road determination flag is 1. If it is 1, the process proceeds to step S29, and if it is 0, the process proceeds to step S22.

  In step S22, timer T2 is reset to zero. The timer T2 is a timer for measuring the time during which the high frequency component due to the road surface input at the secondary pulley rotation speed Nsec of the CVT1 exceeds an entry determination threshold value to be described later.

  In step S23, the high frequency component by the road surface input of the output side rotational speed of CVT1 is extracted. Specifically, the secondary pulley rotation speed Nsec is passed through a low-pass filter that removes fluctuations in the rotation speed caused by a change in vehicle speed, converted to an absolute value, and further passed through a high-pass filter that removes high-frequency components caused by signal noise, Extracts only high-frequency components from road surface input.

  In step S24, the entry determination threshold value used for determining that the vehicle has entered the rough road in the first road surface condition is calculated with reference to the table shown in FIG. As shown in FIG. 4, the entry determination threshold value is set to a larger value as the vehicle speed increases. This is because even if the road surface is the same, the higher the vehicle speed, the shorter the fluctuation of the secondary pulley rotation speed Nsec occurs at shorter intervals. This is because it is impossible to accurately determine the road.

  In step S25, it is determined whether the high-frequency component due to the road surface input extracted in step S23 exceeds the entrance determination threshold value calculated in step S24. If so, the process proceeds to step S26 to increase the timer T2 by ΔT. When not exceeding, it progresses to step S35 and sets 0 to a rough road determination flag.

  In step S27, it is determined whether the timer T2 has exceeded a predetermined time Tb. When exceeding, it progresses to step S28, 1 is set to a bad road determination flag, and when that is not right, it progresses to step S23, and the monitoring of the high frequency component by road surface input is continued. A value of about several seconds is set as the predetermined time Tb, and it may be set to a shorter time if priority is given to the determination speed, and to a longer time if priority is given to determination accuracy.

  Therefore, if the time T2 when the high-frequency component due to road surface input exceeds the on-line determination threshold that changes momentarily according to the vehicle speed becomes longer than the predetermined time Tb, the vehicle travels on a bad road in the first road surface state. 1 is set to the rough road determination flag.

  Steps S29 to S35 are processes for determining that the vehicle has entered a good road from a bad road in the first road surface condition, and is substantially the same as the processes of steps S22 to S28.

  That is, the high-frequency component of the wheel rotation speed is extracted, and the time during which it falls below the missing determination threshold value obtained by referring to the table shown in FIG. 4 is measured by the timer T3. When Tc is exceeded, it is determined that the vehicle has entered the good road from the bad road in the first road surface state, and 0 is set to the bad road determination flag.

  The omission determination threshold value is set to a larger value as the vehicle speed becomes higher, as is the case determination threshold value. The reason why the drop determination threshold is set lower than the entry determination threshold at the same vehicle speed is to prevent frequent switching between the entry determination and the exit determination. In addition, a value of several seconds is set as the predetermined time Tc, and it may be set to a shorter time if priority is given to the determination speed, and to a longer time if priority is given to determination accuracy.

  As described above, when a predetermined time Tb elapses when a high-frequency component due to road surface input enters and exceeds the determination threshold value, the road is determined to be a bad road in the first road surface state, and a state below the missing determination threshold value is predetermined. By determining that the road is a good road when the time Tc has elapsed, it is possible to prevent frequent switching of bad road / good road determination (= value of the bad road determination flag) by picking up instantaneous rotational fluctuations. .

  FIG. 5 is a time chart showing how the rough road traveling in the first road surface state is determined by the first bad road determination.

  As shown in this, even if a high-frequency component exceeding the entry determination threshold is input, if it is instantaneous, it is not determined that the road surface is in a bad road condition, and the determination flag is 0. It remains (time t1). Only when the state in which the high frequency component enters and exceeds the determination threshold value continues for a predetermined time Tb or longer is determined to be the rough road traveling in the first road surface state, the rough road determination flag is set to 1 (time t2 to t3).

  The same applies when the vehicle enters the good road from the bad road in the first road surface state and sets the bad road determination flag to 0, and the state where the high-frequency component falls out and falls below the determination threshold continues for a predetermined time Tc or longer. It is determined that the vehicle is traveling on a good road for the first time, and a bad road determination flag is set to 0 (time t4 to t5).

  The control contents of the transmission controller 12 have been described above. The operational effects of the present invention by performing the above control are summarized as follows.

  According to the present invention, it is determined whether the vehicle is traveling on a rough road in the first road surface state based on the high-frequency component of the output side rotational speed (secondary pulley rotational speed Nsec) of the CVT 1 (first rough road determination, (S1 in FIG. 2A, FIG. 3), traveling on a bad road in a second road surface state where the road surface is more uneven than the first road surface state based on the presence or absence of a temporarily large sudden torque from the drive wheel to the CVT 1 ( Off-road driving) (second bad road determination, S5 to S7 in FIG. 2A), it is determined by the first rough road determination that the vehicle is traveling on a bad road in the first road surface state, and When it is determined by the second rough road determination that the vehicle is traveling off-road, off-road control for protecting CVT 1 from the sudden torque is executed (S9 in FIG. 2A).

  Thus, in order to determine the off-road driving by making the bad road determination double, it is determined that there is an input of the sudden torque in addition to the determination of the rough road driving in the first road surface state. In particular, even on rough roads, the accuracy of judgment on off-road driving is improved, and the deterioration of heat, fuel consumption or power performance due to erroneous off-road control based on misjudgment is prevented. (Effect of the invention described in claim 1).

  Further, in the second rough road determination, the deceleration inertia torque TS is calculated from the rotational deceleration of the input side rotational speed of the CVT 1, and in the above embodiment, from the rotational deceleration of the primary pulley 2 (S5 in FIG. 2A), and the shift of the CVT 1 is performed. The sudden torque determination threshold TM is calculated based on at least one of the ratio, the vehicle speed, the engagement state of the lock-up clutch 6c, and the vehicle drive system (2WD / 4WD) (S6 in FIG. 2A), and the deceleration inertia torque TS suddenly When the torque determination threshold value TM is exceeded, it is determined that the sudden torque has been input (S7 in FIG. 2A). The sudden torque that can be generated varies depending on the transmission ratio of the CVT 1, the vehicle speed, the engagement state of the lock-up clutch 6c, and the drive system. Therefore, the sudden torque threshold TM is made variable according to these, thereby generating the sudden torque. It is possible to make an accurate determination (effect of the invention according to claim 2).

  Further, the off-road control is canceled when a state in which no sudden torque is input continues for a predetermined time or longer (S15 in FIG. 2B). As a result, the off-road control is canceled at the end of the off-road driving, so that deterioration of heat, fuel consumption or power performance due to the unnecessarily continuing off-road control can be prevented. The invention's effect).

  In the above embodiment, when the state where no sudden torque is input continues for a predetermined time or more, it is further determined whether the vehicle is traveling on a rough road by the first rough road determination (S16 in FIG. 2B), and the vehicle is traveling on a rough road. If it is determined that the vehicle is traveling on a rough road, the on-road control is performed (S19 in FIG. 2B).

  Off roads and bad roads in the first road surface condition often exist in succession, and it is unlikely that a good road immediately passes after the off road. Therefore, even if the state in which the sudden torque is not input continues, it does not immediately shift to the on-road control, and once it is determined whether the road condition is the first road surface condition, the first road surface condition is the bad road condition. In some cases, the rough road control is performed, and the on-road control is executed for the first time when the vehicle is not traveling on the rough road in the first road surface condition, so that the CVT 1 can be protected more reliably. Effects of the described invention).

  In off-road control, the secondary pulley pressure Psec is increased to increase the torque capacity of the pulley, and the output torque of the engine 5 is decreased so that the input torque to the CVT 1 is less than the torque capacity of the pulley. Thereby, the belt slip of CVT1 can be suppressed more reliably (the effect of the invention according to claim 5).

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

It is a schematic block diagram of the belt-type continuously variable transmission to which this invention is applied. It is the flowchart which showed the content of the CVT protection control which a transmission controller performs. It is the flowchart which showed the content of the CVT protection control which a transmission controller similarly performs. It is the flowchart which showed the content of the 1st rough road determination which a transmission controller performs. It is a setting table of an entry determination threshold value and an omission determination threshold value. It is the time chart which showed a mode that the bad road driving | running | working of a 1st road surface state was determined by 1st bad road determination.

Explanation of symbols

1 Belt type continuously variable transmission 2 Primary pulley (torque transmission member)
3 Secondary pulley (torque transmission member)
4 Belt 11 Transmission Control Hydraulic Circuit 12 Transmission Controller 21 Off-Road Switch

Claims (5)

It is used in a continuously variable transmission that continuously changes the output rotation of an engine and transmits it to drive wheels. By controlling the belt clamping force of a pair of pulleys that are torque transmitting members, the torque capacity of the torque transmitting member is increased. In the control device for continuously variable transmission that changes and changes the input torque to the torque transmission member by controlling the output torque of the engine,
First rough road determination means for determining whether the vehicle is traveling on a rough road in a first road surface state based on a high-frequency component due to a road surface input of the output side rotational speed of the transmission;
A first judgment is made as to whether or not the vehicle is running on a bad road in a second road surface state where the road surface is more uneven than the first road surface state based on whether or not a suddenly large sudden torque is input from the drive wheel to the transmission. 2 rough road judging means,
The first rough road determination means determines that the vehicle is traveling on a rough road in the first road surface condition, and the second rough road determination means determines that the vehicle is traveling on a rough road in the second road surface state. Offload control means for executing offload control for protecting the continuously variable transmission from the sudden torque when it is determined that,
A control device for a continuously variable transmission.   The second rough road judging means calculates a deceleration inertia torque from the rotational deceleration of the input side rotational speed of the transmission, and calculates a speed ratio of the continuously variable transmission, a vehicle speed, a torque converter of the continuously variable transmission. An abrupt torque determination threshold value is calculated based on at least one of a lockup clutch engagement state and a vehicle driving method, and when the deceleration inertia torque exceeds the abrupt torque determination threshold value, there is an input of the abrupt torque. The control device for continuously variable transmission according to claim 1 or 2, wherein the controller is determined to have met.   3. The offload control is canceled when the offload control is performed by the offload control means and the state in which no sudden torque is input continues for a predetermined time or longer. Control device for continuously variable transmission.   When the off-road control is performed by the off-road control means and the state where the sudden torque is not input continues for a predetermined time or longer, the first rough road determination means travels on the rough road in the first road surface state. A rough road traveling control for protecting the continuously variable transmission from an input of torque smaller than the sudden torque when it is determined that the vehicle is traveling on a rough road in the first road surface state. The continuously variable transmission according to any one of claims 1 to 3, wherein the on-road control is executed when it is determined that the vehicle is not traveling on a bad road in the first road surface traveling state. Machine control device.   The off-road control increases the torque capacity of the torque transmission member by controlling the belt clamping force of the pair of pulleys, which are the torque transmission members, higher than during on-road traveling, and applies the torque transmission member to the torque transmission member. 5. The continuously variable transmission control device according to claim 1, wherein an output torque of the engine is controlled so that an input torque is equal to or less than the torque capacity. 6.