JP5601918B2 - Transmission control device - Google Patents

Description

  The present invention relates to a transmission control apparatus for a vehicle having a torque converter including a direct coupling clutch and a transmission.

  Conventionally, a transmission control device for a continuously variable transmission that combines a torque converter having a lock-up clutch on the input side has been proposed (Patent Document 1). According to this, the lockup clutch is released during various transitions, and at that time, the gear ratio of the continuously variable transmission is corrected so as to be on the low speed side (the side where the gear ratio is large). Here, the gear ratio is a ratio expressed by dividing the input rotation speed by the output rotation speed.

  By the way, an electronic control device for a vehicle equipped with a continuously variable automatic transmission (so-called CVT) has an engine rotational speed so that the rotational speed on the input side of the continuously variable automatic transmission becomes a target rotational speed. To control. Therefore, when the direct coupling clutch (lock-up clutch) is released and the transmission efficiency between the input and output of the torque converter decreases, the direct coupling clutch is used to set the rotational speed on the input side of the continuously variable automatic transmission to the target rotational speed. The engine speed is controlled to be higher than when the is engaged. At this time, if the gear ratio becomes larger than the normal gear ratio, the engine speed further increases.

Japanese Patent No. 3187865

  In the technique disclosed in Patent Document 1, when the lock-up clutch is released, the transmission gear ratio is corrected so as to increase regardless of the operation amount of the accelerator pedal.

  However, when the accelerator pedal is operated as in the case of traveling by the driving force of the engine, the fuel consumption (hereinafter referred to as “fuel consumption”) increases as the engine speed increases. Therefore, if the gear ratio is corrected so that the gear ratio is increased when the direct coupling clutch is released, the engine generates a driving force at a higher rotational speed than usual, resulting in an increase in fuel consumption.

  On the other hand, when the accelerator pedal of the vehicle is not operated, in order to reduce fuel consumption when the engine speed is higher than the engine speed (hereinafter referred to as “idling speed”). A so-called fuel cut is performed to stop fuel consumption.

  However, as described above, when the direct coupling clutch is released and the transmission efficiency between the input and output of the torque converter becomes small, the torque that rotates the engine from the rotating wheel through the transmission during the running is engaged with the direct coupling clutch. Compared to when you are. Therefore, it is necessary to use fuel in order to maintain the rotational speed so as not to be lower than the idling rotational speed. This shortens the fuel cut period and increases fuel efficiency.

  Accordingly, an object of the present invention is to provide a transmission control device that can reduce fuel consumption regardless of the amount of operation of an accelerator pedal when a direct coupling clutch is released.

The present invention includes a transmission that shifts and outputs an output of a vehicle drive source input via a torque converter including a direct coupling clutch, and an operation amount detection means that detects an operation amount of an accelerator pedal of the vehicle. A transmission control apparatus for a vehicle, wherein a determination means for determining whether or not the direct coupling clutch is disengaged, and a transmission gear ratio of the transmission to a traveling speed of the vehicle, the operation amount, and a predetermined control pattern Control means based on the control means, and the control means is configured to release the direct coupling clutch by the determining means when the direct coupling clutch is controlled to be engaged when the operation amount is less than a predetermined value. If it is determined to have been estimates that there is an abnormality in the operation of the lockup clutch, than when the direct clutch is determined to have been concluded, the running speed Depending and changes the control pattern so that the rotation speed is increased to be input to the transmission to another control pattern.

According to the present invention, the control means controls the speed ratio of the transmission based on the traveling speed of the vehicle (hereinafter referred to as “vehicle speed”), the operation amount of the accelerator pedal, and a predetermined control pattern (for example, a shift map). To do. Then, when the operation amount of the accelerator pedal is less than a predetermined value, when it is determined by the determination means that the direct coupling clutch is released while the direct coupling clutch is controlled to be engaged, the direct coupling clutch is engaged. Compared to a case where it is determined that the speed is determined, the control pattern is changed to another control pattern in which the rotational speed input to the transmission is increased according to the vehicle speed.

  Here, the case where the operation amount of the accelerator pedal is less than a predetermined value is, for example, a case where it is determined that it is not required to drive the vehicle by outputting the driving force from the driving source of the vehicle.

And, when the operation amount of the accelerator pedal is less than a predetermined value, if the direct coupling clutch is released when the direct coupling clutch is controlled to be engaged, the vehicle is not running with the driving force from the driving source. Assuming that the transmission is in a state, the transmission ratio is controlled so that the input rotational speed of the transmission is increased with another control pattern. For this reason, the rotational speed of the drive source increases in conjunction with the input rotational speed of the transmission, and the fuel cut period can be maintained longer, so that fuel consumption can be reduced.

  On the other hand, if the amount of operation of the accelerator pedal is equal to or greater than a predetermined value, it is assumed that the vehicle is running with the driving force from the driving source, so there is no increase in the rotational speed of the driving source due to the change to another control pattern. Fuel consumption can be reduced.

  Therefore, according to the present invention, fuel consumption can be reduced regardless of the amount of operation of the accelerator pedal when the direct clutch is released.

  In the present invention, the speed ratio is a value obtained by dividing the input rotational speed by the output rotational speed, and the other control pattern is compared with a control pattern when it is determined that the direct clutch is engaged. Thus, it is preferable that the control pattern has a large gear ratio.

  According to this, another control pattern is a control pattern in which the gear ratio is larger than the control pattern when it is determined that the operation amount of the accelerator pedal is less than a predetermined value and the direct clutch is engaged.

Therefore, in a situation where it is determined that the vehicle is not required to travel with the driving force output from the vehicle drive source when the direct coupling clutch is released, the transmission from the wheels during the traveling of the vehicle. The number of revolutions of the engine that rotates through can be increased.
In the present invention, the control means is the case where the operation amount of the accelerator pedal detected by the operation amount detection means does not change, and the difference between the actual slip ratio of the direct coupling clutch and the target slip ratio is not less than a predetermined value. It is preferable to estimate that there is an abnormality in the operation of the direct coupling clutch when this state continues for a predetermined time. Thereby, the fuel consumption when it is estimated that the operation of the direct coupling clutch is abnormal can be suppressed.

The figure which shows schematic structure of the vehicle containing the transmission control apparatus of this embodiment. The figure (transmission map) showing the relationship between the vehicle speed Vrr and the drive pulley rotation speed by the state of the lockup clutch 16d. (A) uses a normal shift map, and (b) shows changes over time in the drive pulley rotational speed and engine rotational speed when the lockup clutch 16d is used and the accelerator pedal is off. Figure representing. The flowchart which shows the process sequence of the shift map switching process which ECU54 of FIG. 1 performs.

  FIG. 1 is a diagram illustrating a schematic configuration of a vehicle including a transmission control device according to the present embodiment.

  An internal combustion engine (engine) is mounted on the vehicle as a drive source. The output of the engine 12 is input to a continuously variable transmission (CVT) 14.

  The CVT 14 includes a drive pulley 14a connected to the main shaft MS, a driven pulley 14b connected to the countershaft CS, a metal belt 14c hung between them, and a hydraulic mechanism (see FIG. The output of the engine 12 input from the main shaft MS via the torque converter 16 and the forward clutch 20 is changed at a continuously variable transmission ratio.

  The torque converter 16 is a fluid torque converter that uses a fluid as a driving force transmission medium, and includes a pump impeller 16a, a turbine runner 16b, a stator 16c, and a lock-up clutch 16d as the engine 12 rotates.

  The pump impeller 16a is rotated by the driving force of the engine 12, and power is transmitted to the turbine runner 16b by the flow of the internal fluid output by the centrifugal force of this rotation.

  The stator 16c is disposed between the pump impeller 16a and the turbine runner 16b in order to control the flow of fluid. Further, the stator 16c is provided with a one-way clutch (not shown) so as not to rotate in the reverse direction, and can be fixed so as not to rotate.

  The lock-up clutch 16d is arranged so that the pump impeller 16a and the turbine runner 16b can be mechanically connected. When the lockup clutch 16d is engaged, the power transmission efficiency between the pump impeller 16a and the turbine runner 16b is 1. When the lock-up clutch 16d is released, the power transmission efficiency between the pump impeller 16a and the turbine runner 16b is less than 1, and the energy corresponding to the reduced efficiency is converted into thermal energy.

  That is, when a difference occurs in the rotation speed between the pump impeller 16a and the turbine runner 16b, the difference in the rotation speed can be absorbed by opening the lockup clutch 16d. Further, in a normal traveling state, the lockup clutch 16d is fastened to prevent a decrease in transmission efficiency.

  The lock-up clutch 16d corresponds to the direct coupling clutch in the present invention.

  The output of the engine 12 shifted by the CVT 14 is transmitted from the counter shaft CS to the front wheels 30FL and 30FR via the reduction gear 22 and the front differential mechanism 26. Thus, the vehicle shifts the output of the engine 12 with the CVT 14 to drive the front wheels 30FL and 30FR.

  In the CVT 14, an NDR sensor 40 is provided in the vicinity of the drive pulley to generate an output corresponding to the input rotational speed of the CVT 14, and an NDN sensor 42 is provided in the vicinity of the driven pulley to output in accordance with the output rotational speed of the CVT 14. Produce.

  Wheel speed sensors 44 are provided in the vicinity of the drive shafts (not shown) of the left and right front wheels 30FL and 30FR, respectively, and generate outputs corresponding to the rotational speeds (wheel speeds) of the left and right front wheels 30FL and 30FR.

  An accelerator opening sensor 46 is provided in the vicinity of an accelerator pedal (not shown) on the driver's seat floor of the vehicle, and outputs a value corresponding to the accelerator opening (depressing amount of the accelerator pedal by the driver) AP. When the accelerator pedal of the vehicle is not operated (hereinafter referred to as “accelerator pedal off”), the value is 0. When the accelerator pedal is operated, the value output from the accelerator opening sensor 46 increases according to the amount of operation. To do.

  In the present embodiment, the accelerator opening sensor 46 corresponds to the operation amount detection means in the present invention.

  An electronic control unit (ECU) 54 is a storage device (memory) including a CPU 54a that executes various arithmetic processes, various arithmetic programs executed by the CPU 54a, various tables, and ROM and RAM that store arithmetic results. 54b, and inputs various electric signals such as the output of the sensor, and outputs a drive signal to the outside based on the calculation result. Further, the ECU 54 controls operations of the CVT 14 and the torque converter 16.

  The ECU 54 is supplied with the outputs of the accelerator opening sensor 46, the NDR sensor 40, and the NDN sensor 42. Further, the rotational speed of the pump impeller 16a and the rotational speed of the turbine runner 16b are supplied to the ECU 54 from a rotational speed sensor (not shown) that detects the rotational speed of the pump impeller 16a and the rotational speed of the turbine runner 16b.

  Further, since the accelerator opening AP may become a value larger than 0 due to a measurement error or an erroneous operation of the accelerator pedal, the ECU 54 determines that the accelerator pedal is less than a value (predetermined value) estimated to be a measurement error or an erroneous operation. It is off. This predetermined value is determined in advance by experiments or the like and stored in the memory 54b of the ECU 54.

  In the present embodiment, the CPU 54a of the ECU 54 functions as the determination unit 54a1 and the control unit 54a2 in the present invention.

  In the present embodiment, a continuously variable transmission (CVT) is used as the transmission, but an automatic stepped transmission may be used.

  The release or engagement of the lockup clutch 16d is controlled by the ECU 54 in accordance with the state of the vehicle. For example, the lock-up clutch 16d is released when the vehicle starts or stops.

  Further, the ECU 54 controls the engagement transient state of the lockup clutch 16d so that the slip rate of the torque converter 16 becomes a target slip rate. The slip ratio is determined by dividing the rotational speed of the turbine runner 16b by the rotational speed of the pump impeller 16a. The target slip ratio is determined by searching a map from the driving state of the vehicle (the amount of change in the vehicle speed Vrr and the accelerator pedal opening AP). This map is determined in advance by experiments or the like and stored in the memory 54b.

  However, the lock-up clutch 16d may be released regardless of the control of the ECU 54. For example, when there is an abnormality in a hydraulic circuit (not shown) that controls the operation of the torque converter 16, the lockup clutch 16d may be released. Therefore, it is necessary to be able to determine whether or not the lockup clutch 16d is released.

  Therefore, in the present embodiment, the determination unit 54a1 of the ECU 54 determines that the lockup clutch 16d is engaged when the difference between the rotational speed of the pump impeller 16a and the rotational speed of the turbine runner 16b is equal to or less than a predetermined value. If it is greater than the predetermined value, it is determined that the lockup clutch 16d is released.

  The predetermined value may be set to 0, or may be set in consideration of a measurement error of the rotation speed sensor. This predetermined value is determined in advance by experiments or the like and stored in the memory 54b.

  The determination of whether or not the lock-up clutch 16d is released corresponds to the determination of whether or not the direct coupling clutch is released by the determination unit 54a1 in the present invention.

  In addition, when the ECU 54 controls the lockup clutch 16d to be engaged, if the determination unit 54a1 determines that the direct coupling clutch is released, the operation of the lockup clutch 16d is abnormal. Can be estimated. In addition, when the change amount of the accelerator pedal opening AP is stable (during so-called cruise driving), when the state in which the difference between the actual slip rate and the target slip rate is equal to or greater than a predetermined value continues for a predetermined time. Also, it is estimated that there is an abnormality in the operation of the lockup clutch 16d.

  For the predetermined value and the predetermined time, a value capable of sufficiently estimating the abnormality of the operation of the lockup clutch 16d is determined in advance by experiments or the like and stored in the memory 54b.

  Next, the control of the gear ratio in a state where the lockup clutch 16d is released will be described.

  In the state where the lock-up clutch 16d is released, the transmission efficiency between the drive pulley 14a and the driven pulley 14b decreases.

  When the accelerator pedal is off, the rotation of each wheel while the vehicle is traveling is transmitted to the engine 12 via the countershaft CS, the driven pulley 14b, the belt 14c, the drive pulley 14a, and the torque converter 16. When the transmission efficiency is lowered due to the release of the lock-up clutch 16d, the rotational speed of the engine 12 due to the rotation of the wheels (hereinafter referred to as “engine rotational speed”) decreases.

  As described above, when the engine speed is equal to or higher than a certain value, fuel cut is performed to improve fuel consumption. When the lock-up clutch 16d is released, the engine speed decreases as described above, so that it becomes lower than the idling speed NID, fuel cut is stopped, and fuel consumption may increase.

  Therefore, when the lock-up clutch 16d is disengaged and the accelerator pedal is off, the control means 54a2 has a rotational speed input to the CVT 14 (the rotational speed of the drive pulley 14a, hereinafter referred to as “drive pulley rotational speed”). By changing to a control pattern (shift map) that increases, the gear ratio of the CVT 14 is controlled to reduce fuel consumption.

  Even when the lockup clutch 16d is released, when the accelerator pedal is operated, that is, when the vehicle is required to travel by the driving force of the engine 12, the rotation of the engine 12 is higher than necessary. When driving force is generated by a number, fuel consumption increases.

  The ECU 54 controls the engine rotational speed so that the rotational speed input to the CVT 14 becomes the target rotational speed. Therefore, when the lockup clutch 16d is released and the transmission efficiency of the torque converter 16 decreases, the engine speed is increased so that the rotation speed input to the CVT 14 does not decrease. And it drive | works with the driving force of the engine 12 with the increased engine speed.

  At this time, as in the case where the accelerator pedal is off, if the shift map is changed so that the rotation speed input to the CVT 14 is increased, the engine rotation speed is further increased. Therefore, when the accelerator pedal is operated and the vehicle is driven by the driving force of the engine, the engine speed is increased by reducing the transmission efficiency of the torque converter 16 by controlling the transmission ratio of the CVT 14 using the normal shift map. Prevents an increase in the number of revolutions other than that and suppresses fuel consumption.

  FIG. 2 shows an example of a relationship (shift map) between the vehicle speed Vrr and the drive pulley rotation speed at a predetermined accelerator opening AP. The horizontal axis is the vehicle speed Vrr, and the vertical axis is the drive pulley rotational speed.

  In this embodiment, since the transmission is CVT, the gear ratio is changed so that the drive pulley rotational speed hardly changes with respect to the change in the vehicle speed Vrr. That is, the control means 54a2 controls the transmission ratio of the CVT 14 from the vehicle speed Vrr and the drive pulley rotational speed in accordance with the shift map as shown in FIG. If the vehicle speed (wheel rotation speed) Vrr and the drive pulley rotation speed are determined, the gear ratio between the drive pulley 14a and the wheel can be determined. A speed ratio obtained by removing a fixed speed ratio (for example, the speed ratio of the final gear) from the speed ratio is determined as the speed ratio of the transmission, and the control unit 54a2 controls the speed ratio of the CVT 14 so as to be the speed ratio.

  The shift map for releasing the lockup clutch 16d and when the accelerator pedal is off (solid line in FIG. 2) is such that the drive pulley rotational speed is larger than the normal shift map (broken line in FIG. 2). It is a shift map.

  When the lock-up clutch 16d is released and the accelerator pedal is off, the transmission efficiency from the turbine runner 16b on the wheel side to the pump impeller 16a on the engine side decreases, so the gear ratio is increased and the drive pulley rotates. By increasing the number, the rotational speed of the pump impeller 16a (same as the engine rotational speed) is increased.

  The shift map corresponds to the control pattern in the present invention. Further, when it is determined that the lockup clutch 16d is released and the accelerator pedal is turned off, the shift map is changed from the normal shift map (broken line in FIG. 2) when the lockup clutch is released and the accelerator pedal is turned off. Changing to the shift map (solid line in FIG. 2) corresponds to changing to another control pattern in the present invention. Although omitted in FIG. 2, a shift map is prepared for each accelerator opening AP.

  Further, when it is estimated that there is an abnormality in the operation of the lockup clutch 16d, when the accelerator pedal is turned off, the shift map is changed to a map for releasing the lockup clutch and turning off the accelerator pedal (solid line in FIG. 2). May be.

  Here, when it is estimated that there is an abnormality in the operation of the lockup clutch 16d, as described above, the direct coupling clutch is released when the ECU 54 controls to lock the lockup clutch 16d. Or when the change amount of the accelerator pedal opening AP is stable, the state where the difference between the actual slip rate of the torque converter 16d and the target slip rate is a predetermined value or more continues for a predetermined time. Is the case.

  That is, when it is estimated that there is an abnormality in the operation of the lockup clutch 16d, it is the same as the state in which the lockup clutch 16d is released, so the shift map used when the lockup clutch is released and the accelerator pedal is off is displayed. change. Thereby, the fuel consumption when it is estimated that there is an abnormality in the operation of the lockup clutch 16d can be suppressed.

  FIG. 3 shows an example of temporal changes in the engine speed and the drive pulley speed when the lock-up clutch 16d is opened and the accelerator pedal is off.

  FIG. 3A shows the change over time when the normal shift map is used, and FIG. 3B shows the shift map when the lockup clutch 16d is released and the accelerator pedal is off. Shows the time change during use. 3A and 3B, the horizontal axis represents time, and the vertical axis represents the rotation speed. i represents the drive pulley rotational speed, and j represents the engine rotational speed. NID represents the idling speed. When the engine speed becomes less than this speed, fuel is used to maintain the idling speed NID.

  3A and 3B, the lockup clutch 16d is released and the accelerator pedal is turned off, so that the engine 12 is rotated by the rotation of each wheel while the vehicle is traveling. Therefore, the engine speed is smaller than the drive pulley speed. Further, because the accelerator pedal is off, the vehicle speed gradually decreases as time passes. Therefore, the drive pulley rotational speed and the engine rotational speed also gradually decrease as time passes.

  In FIG. 3A, fuel cut is performed before the time ta because the engine speed is equal to or higher than the idling speed NID. However, after the time ta, the fuel is discharged because the engine speed is lower than the idling speed NID. Is consumed.

  The control means 54a2 uses the shift map when the lock-up clutch 16d is disengaged and the accelerator pedal is off, and controls the CVT 14 so as to increase the drive pulley rotational speed. As shown, the engine speed is equal to or higher than the idling speed NID even after time ta. Therefore, the fuel cut period can be lengthened, and fuel consumption can be reduced.

  FIG. 4 is a flowchart showing the procedure of the shift map switching process of the present invention executed by the CPU 54a. The control processing program shown in this flowchart is called and executed every predetermined time (for example, 10 msec).

  In the first step ST1, as described above, it is determined whether or not the lockup clutch 16d is released. When the determination result in step ST1 is YES, the process proceeds to step ST2. The process of step ST1 corresponds to the determination by the determination unit 54a1 in the present invention.

  In step ST2, it is determined whether or not the accelerator pedal is off. When the accelerator pedal depression amount detected by the accelerator opening sensor (operation amount detection means) 46 is less than a predetermined value, it is determined that the accelerator pedal is off. By determining whether or not the accelerator pedal is off, it is determined whether or not there is no need to output a driving force from the engine 12.

  If the decision result in the step ST2 is YES, the process proceeds to a step ST3 to switch to a shift map for releasing the lockup clutch that suppresses a decrease in the engine speed and for turning off the accelerator pedal as described above. .

  If the determination result in step ST1 or ST2 is NO, the process proceeds to step ST4, and the normal shift map is switched.

  When the processes of steps ST3 and ST4 are completed, this control process ends.

  As described above, when it is determined that the lock-up clutch is disengaged (step ST1) and when the accelerator pedal is off (step ST2), the lock-up clutch is disengaged to suppress a decrease in engine speed. And the shift map for when the accelerator pedal is off (step ST3).

  As a result, when the engine 12 does not need to output driving force (when the accelerator pedal is off), the gear ratio is controlled by a gear shift map that increases the gear ratio, so that the vehicle can travel from the wheels while the vehicle is traveling. The number of revolutions of the engine that is rotated via the transmission can be increased, and the fuel cut period can be kept longer to reduce fuel consumption. Further, when the engine 12 needs to output a driving force (when the accelerator pedal is not off), the gear ratio is controlled by a normal shift map to suppress the increase in the rotational speed of the engine 12 and to improve the fuel efficiency. Can be reduced.

  Therefore, it is possible to provide a transmission control device that can reduce fuel consumption regardless of the operation amount of the accelerator pedal even when the direct coupling clutch is released.

  DESCRIPTION OF SYMBOLS 12 ... Engine (drive source), 14 ... CVT (transmission), 16 ... Torque converter, 16d ... Lock-up clutch (direct coupling clutch), 44 ... Wheel speed sensor, 46 ... Accelerator opening sensor (operation amount detection means), 54 ... ECU, 54a ... CPU, 54a1 ... determination means, 54a2 ... control means, 54b ... memory.

Claims (3)

A transmission for a vehicle having a transmission for shifting and outputting an output of a vehicle drive source input via a torque converter having a direct coupling clutch, and an operation amount detection means for detecting an operation amount of an accelerator pedal of the vehicle. A control device,
Determining means for determining whether or not the direct clutch is disengaged;
Control means for controlling the speed ratio of the transmission based on the traveling speed of the vehicle, the operation amount, and a predetermined control pattern;
Wherein when the operation amount is smaller than the predetermined value, when the direct clutch is determined to be opened by said determining means when and are controlled so as to enter into the direct clutch, the It is estimated that there is an abnormality in the operation of the direct coupling clutch, and the rotational speed input to the transmission is increased according to the traveling speed as compared to when it is determined that the direct coupling clutch is engaged. A transmission control device, wherein a control pattern is changed to another control pattern. The transmission control device according to claim 1,
The speed ratio is a value obtained by dividing the input rotation speed by the output rotation speed,
The transmission control apparatus according to claim 1, wherein the another control pattern is a control pattern having a larger speed ratio than a control pattern when it is determined that the direct coupling clutch is engaged. 3. The transmission control apparatus according to claim 1 or 2, wherein the control means is an actual slip ratio and a target of the direct clutch when the operation amount of the accelerator pedal detected by the operation amount detection means does not change. A transmission control device characterized in that it is estimated that there is an abnormality in the operation of the direct coupling clutch when a state in which the difference from the slip ratio is equal to or greater than a predetermined value continues for a predetermined time.

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