JP6264571B2 - Control device for power transmission mechanism - Google Patents

Description

  The present invention relates to a control device for a power transmission mechanism.

  A vehicle is generally driven by transmitting power from a power source such as an internal combustion engine to drive wheels via a power transmission mechanism. When such a vehicle is stopped by a braking mechanism such as a brake, the power source is still loaded with power being transmitted from the power source to the drive wheels via the power transmission mechanism, For example, it may lead to problems such as deterioration of fuel consumption and engine stall. For example, in the case of a vehicle having a power transmission mechanism having an automatic transmission mechanism such as a continuously variable transmission (CVT), when the shift position is in the drive range (D range), even if the vehicle is stopped A load is always applied to the power source due to the creep phenomenon in the torque converter. The load resulting from such a creep phenomenon becomes a cause of deterioration in fuel consumption.

  Therefore, an intermittent device that transmits power by frictional engagement (hereinafter, such a device may be collectively referred to as a “clutch”) is interposed in the power transmission mechanism, and the degree of engagement of the clutch when the vehicle is stopped. (Hereinafter referred to as “degree of engagement”) is known to reduce power transmission. As a result, it is possible to suppress the deterioration of fuel consumption caused by the load applied to the power source even when the vehicle is stopped as described above. Such control of the power transmission device may be hereinafter referred to as “neutral control”.

  In the above, when the clutch engagement degree is lowered at once and the clutch is released at once, problems such as an impact caused by a sudden change in driving force may occur. Therefore, the clutch engagement degree is lowered at a stretch until immediately before the clutch engagement members start to slide relative to each other (the clutch release starts), and thereafter, the clutch engagement degree is gradually lowered (sweep down). It is known to release the clutch as quickly as possible while suppressing the occurrence of impact. Note that “clutch release” here refers not only to the state where the clutch is completely released and the degree of engagement being 0 (zero), but also to the extent that effects such as suppression of fuel consumption deterioration can be sufficiently obtained. This is a broad concept including a state in which the degree of engagement of the clutch is reduced.

  However, there are individual differences in the clutch due to, for example, variations in quality at the time of manufacture and secular changes after manufacture. Specifically, for example, there is an individual difference in the friction coefficient of the engagement member (friction material) of the clutch. As a result, the command value of hydraulic pressure and / or electric power (hereinafter sometimes referred to as “engagement command value”) for controlling the degree of engagement of the clutch is set to a predetermined value and the above-described value is set. Thus, even if it is attempted to control the degree of engagement of the clutch, the desired effect may not be achieved.

  Specifically, when the friction coefficient of the engagement member of the clutch is lower than a specified value, the clutch is engaged even though the engagement command value for the clutch is set to a value corresponding to the state immediately before the clutch release starts. There is a possibility that the impact is generated by being released at once. On the contrary, when the friction coefficient of the clutch engaging member is higher than the specified value, the clutch release does not start even at the engagement command value that should have been released, and the clutch is not released. There is a risk that the time required to complete is excessively long (a time lag occurs). In this case, for example, effects such as suppression of fuel consumption deterioration cannot be sufficiently obtained.

  Therefore, the engagement command value when the clutch engagement level reaches the desired target value (the engagement level corresponding to the clutch disengaged state) is learned, and this learned engagement command value is used for the next and subsequent neutral control. It has been proposed to use when executing (see, for example, Patent Document 1). Specifically, in a power transmission mechanism including a fluid power transmission device that transmits power via a fluid (hereinafter, such a device may be collectively referred to as a “torque converter”), as described above. In addition, until the clutch is released, the degree of engagement of the clutch is reduced at once, and thereafter the degree of engagement of the clutch is swept down.

  During the sweep-down period, the clutch release start is detected based on the turbine speed of the torque converter, and then the clutch engagement command value is adjusted so that the turbine speed matches the predetermined target value. To do. As a result, an engagement command value for the clutch when the turbine rotational speed matches a predetermined target value is learned, and the learned engagement command value is used as a target for the engagement command value at the next execution of neutral control. It is used as a value (hereinafter, sometimes referred to as “target engagement command value”). According to this, even when there is an individual difference in the clutch as described above, the clutch is released while suppressing the occurrence of an impact due to a sudden change in the driving force, and at the appropriate engagement degree as quickly as possible. A clutch released state (neutral state) can be achieved.

JP 2004-053949 A

  By the way, in the technical field, for the purpose of further improving fuel consumption, it is considered that neutral control is executed even when the vehicle is not stopped (for example, during traveling before stopping) when a predetermined condition is satisfied. ing. Specifically, for example, when the vehicle speed (vehicle speed) is less than a predetermined value and the accelerator opening is less than a predetermined value, the clutch provided in the power transmission mechanism is released even if the vehicle is not stopped. It has been studied to further improve the fuel consumption by allowing the vehicle to coast. The neutral control that is executed at times other than when the vehicle is stopped is sometimes referred to as “traveling neutral control”. On the other hand, the neutral control executed when the vehicle is stopped may be hereinafter referred to as “neutral control when the vehicle is stopped”.

  In the neutral control during driving, the target engagement command value for the clutch is learned in the same manner as in the neutral control during stopping, so that even if there are individual differences in the clutch, it is possible to suppress the occurrence of impacts due to sudden changes in driving force. It is considered that it is possible to release the clutch and achieve the released state (neutral state) of the clutch with an appropriate degree of engagement as quickly as possible. However, in reality, it is extremely difficult to learn the target engagement command value in the neutral control during traveling, as in the neutral control during stopping. A description will be given below of a case where the neutral control at the time of stopping and the neutral control at the time of running are executed in the power transmission mechanism having a torque converter on the upstream side (the side closer to the power source) than the clutch.

  When neutral control is executed when the vehicle is stopped, the drive wheels are not rotating, and the rotation speed of the output shaft of the clutch (the power transmission shaft on the drive wheels) is constant at 0 (zero). Therefore, while the clutch is engaged, the rotational speed of the clutch input shaft (power transmission shaft on the power source side) is also constant at 0 (zero). On the other hand, the rotational speed of the power source is kept constant at the idle rotational speed. The torque converter turbine runner is linked to the clutch input shaft, and the torque converter pump impeller is linked to the output shaft of the power source. Thus, the speed ratio of the torque converter (ratio of turbine runner rotational speed to pump impeller rotational speed) is also constant at zero. That is, the input torque to the clutch is also constant. Thereafter, as the engagement command value for the clutch sweeps down, the clutch starts to be released at a certain point in time, and the rotational speed of the clutch input shaft (rotational speed of the turbine runner) starts to increase. The clutch release factor in this case is a decrease in the clutch torque capacity due to sweeping down of the engagement command value for the clutch.

  On the other hand, when running neutral control is performed, the drive wheels rotate according to the vehicle speed, and the rotational speed of the output shaft of the clutch changes according to the change in the vehicle speed. Therefore, while the clutch is engaged, the rotational speed of the input shaft of the clutch also changes according to the change in the vehicle speed. In addition, the rotational speed of the power source is not necessarily maintained constant at the idle rotational speed, and changes according to changes in the vehicle speed or the like. Therefore, the speed ratio of the torque converter also changes according to changes in the vehicle speed and the like. For example, when the rotational speed of the input shaft of the clutch (rotational speed of the turbine runner) decreases as the vehicle speed decreases, the speed ratio of the torque converter also decreases. Conversely, when the rotational speed of the input shaft of the clutch (rotational speed of the turbine runner) increases as the vehicle speed increases, the speed ratio of the torque converter also increases.

  When the speed ratio of the torque converter varies as described above, the torque amplification factor in the torque converter also varies, so the input torque to the clutch also varies. Thereafter, as the engagement command value for the clutch sweeps down, the clutch starts to be released at a certain point in time, and the rotational speed of the clutch input shaft (rotational speed of the turbine runner) starts to increase. However, the clutch release factor in this case includes not only a decrease in the torque capacity of the clutch due to the sweep-down of the engagement command value for the clutch, but also a fluctuation in the input torque to the clutch.

  That is, in the neutral control during traveling, the clutch is released while suppressing the occurrence of an impact due to a sudden change in the driving force by sweeping down the engagement command value for the clutch, and at the appropriate engagement degree as quickly as possible. Even if the clutch release state (neutral state) is to be achieved, the timing at which the clutch release starts and the speed ratio of the torque converter at that time are influenced by fluctuations in the input torque to the clutch. Thus, the clutch release mechanism in the running neutral control is complicated, and it is extremely difficult to learn the target engagement command value for the clutch in the running neutral control, as in the stationary neutral control.

  The present invention has been made to address the above-described problems. That is, the present invention learns the target engagement command value for the clutch even in the neutral control during traveling, so that even if there is an individual difference in the clutch, the clutch can be suppressed while suppressing the occurrence of an impact due to a sudden change in the driving force. It is an object of the present invention to provide a control device for a power transmission mechanism that can release a clutch and achieve a clutch released state (neutral state) with an appropriate degree of engagement as quickly as possible.

  As a result of earnest research, the present inventor has maintained a constant engagement command value for releasing the clutch at a predetermined target engagement command value in the neutral control during traveling, and when the clutch actually starts to be released It has been found that the above object can be achieved by correcting this target engagement command value based on the difference between the speed ratio of the torque converter and a predetermined target speed ratio.

  More specifically, in running neutral control of a power transmission mechanism including a torque converter and a clutch, the engagement command value for releasing the clutch is not a sweep-down as in the neutral control during stopping, but is predetermined. The target engagement command value is maintained constant. The target engagement command is based on the difference between the torque converter speed ratio and the predetermined target speed ratio (for example, the difference and ratio between the two) when the clutch actually starts to be released as the vehicle speed decreases. Correct (update) the value. The target engagement command value corrected in this manner is used in the next traveling neutral control. In this way, it has been found that the target engagement command value for releasing the clutch can also be learned in the running neutral control.

  In view of the above points, a control device for a power transmission mechanism according to the present invention (hereinafter sometimes referred to as “the present invention device”) is a vehicle having a power source, drive wheels, an accelerator, and a brake. The present invention is applied to a power transmission mechanism that transmits power from the power source to the drive wheels. That is, the device of the present invention can be applied to a power transmission mechanism provided in a general vehicle such as an automobile. The configuration of the vehicle including the power transmission mechanism will be described in detail later.

  The apparatus of the present invention includes neutral control execution means and detection means. The neutral control execution means is an engagement that is a command value for adjusting the degree of engagement that is the degree of engagement of the clutch that interrupts transmission of the power in the power transmission mechanism when a predetermined neutral control execution condition is satisfied. Neutral control is performed to adjust the command value to bring the clutch into a neutral state. That is, the power transmission mechanism to which the device of the present invention is applied includes a clutch for intermittently transmitting power.

  The detecting means includes an engine rotational speed that is a rotational speed of the power source, a turbine rotational speed that is a rotational speed of a turbine runner of a torque converter that transmits the power from the power source to the clutch in the power transmission mechanism, and A vehicle speed that is a traveling speed of the vehicle is detected. That is, the power transmission mechanism to which the device of the present invention is applied includes a torque converter that transmits power from the power source to the clutch.

  Further, the neutral control execution means includes a release command unit, a release speed ratio calculation unit, and a target engagement command value update unit. Each of the release command unit, the release speed ratio calculation unit, and the target engagement command value update unit will be described below.

  The release command unit maintains the engagement command value constant at a predetermined target engagement command value when the vehicle speed at the start of the neutral control is higher than a predetermined first speed, and the degree of engagement of the clutch. Reduce. Thus, the engagement command value for the clutch when the release command unit lowers the degree of engagement of the clutch is not swept down as in the neutral control at the time of stop, but is constant at a predetermined target engagement command value. Maintained. As a result, the engagement degree and torque capacity of the clutch are maintained at values corresponding to the target engagement command value.

  The disengagement speed ratio calculation unit is configured to release the clutch based on the turbine rotation speed and the engine rotation speed when the turbine rotation speed that has been lowered with the decrease in the vehicle speed starts to increase. A release speed ratio which is a speed ratio of the torque converter is calculated. The turbine rotational speed that has been lowered as the vehicle speed decreases in this way starts to increase due to the start of the release of the clutch.

  In this case, the clutch release factor is an increase in torque gain of the torque converter due to a decrease in the speed ratio of the torque converter due to a decrease in turbine rotational speed accompanying a decrease in vehicle speed. As a result, the input torque to the clutch increases, and the clutch engagement members begin to slide with each other (that is, the clutch starts to be released) even though the degree of engagement of the clutch has not changed. That is, at this time, since the engagement command value is kept constant at the target engagement command value, a decrease in torque capacity due to a decrease in the degree of engagement of the clutch is excluded from the clutch release factor. In this case, as described above, the clutch is gradually released as a result of the gradual increase in the input torque to the clutch as the vehicle speed decreases, so that it is possible to suppress the occurrence of an impact due to a sudden change in driving force.

  The target engagement command value update unit corrects the target engagement command value based on a difference between the release speed ratio and a predetermined target speed ratio. Specifically, the target engagement command value update unit is configured to release the release speed when the release command unit maintains the clutch engagement command value constant at the target engagement command value to reduce the degree of clutch engagement. The target engagement command value is corrected so that the ratio approaches the target speed ratio.

  Next time, when the release command unit keeps the clutch engagement command value constant at the target engagement command value and decreases the degree of clutch engagement, the target engagement command value corrected as described above is used. Used by the release command. Thereby, the device of the present invention can learn a target engagement command value for releasing the clutch with an appropriate degree of engagement in the running neutral control. In other words, the device according to the present invention learns the target engagement command value for the clutch even in the neutral control during traveling, thereby suppressing the occurrence of an impact due to a sudden change in the driving force even when there is an individual difference in the clutch. The clutch is released, and the released state (neutral state) of the clutch with an appropriate degree of engagement can be achieved as quickly as possible.

  By the way, the neutral control execution condition can be appropriately determined according to, for example, a use situation assumed in a vehicle in which neutral control is to be executed, a configuration of the vehicle, and the like. Specifically, the neutral control execution means is in a state where at least the vehicle speed is less than a predetermined second speed, the accelerator opening is less than the predetermined first opening, and the brake is operating. The neutral control execution condition may be satisfied when the operation continues for a predetermined first time or longer.

  By the way, the above-mentioned “difference between release speed ratio and target speed ratio” may be, for example, “difference between release speed ratio and target speed ratio” or “ratio of release speed ratio to target speed ratio”. It may be.

  In the former case, when the difference obtained by subtracting the target speed ratio from the disengagement speed ratio is larger than a predetermined first upper limit value, the target engagement command value update unit increases the degree of engagement of the clutch. When the difference obtained by correcting the target engagement command value and subtracting the target speed ratio from the release speed ratio is smaller than a predetermined first lower limit value, the degree of engagement of the clutch is made smaller. It may be configured to correct the target engagement command value.

  In the latter case, the target engagement command value update unit is configured to increase the degree of engagement of the clutch when the ratio of the release speed ratio to the target speed ratio is greater than a predetermined second upper limit value. The target engagement command value is corrected, and when the ratio of the release speed ratio to the target speed ratio is smaller than a predetermined second lower limit value, the target engagement is set so that the degree of engagement of the clutch becomes smaller. It may be configured to correct the command value.

  Other objects, other features, and attendant advantages of the present invention will be readily understood from the description of each embodiment of the present invention described with reference to the following drawings.

It is a mimetic diagram showing an example of composition of a vehicle to which a control device (this control device) of a power transmission device concerning one embodiment of the present invention is applied. It is a typical time chart which shows an example of transition of vehicle speed, brake operation, engagement command value, and various rotation speeds in neutral control at the time of stop. It is a typical time chart which shows an example of transition of the vehicle speed in the neutral control at the time of driving, operation of a brake, an engagement command value, and various rotation speeds. FIG. 4 is a partially enlarged view of a time chart showing neutral control during traveling shown in FIG. 3.

  Hereinafter, a control device for a power transmission mechanism according to one embodiment of the present invention (hereinafter sometimes referred to as “the present control device”) will be described with reference to the drawings.

(Constitution)
As described above, a vehicle including a power transmission device to which the present control device is applied has the same configuration as a general vehicle. For example, the vehicle includes a power transmission mechanism 170, various operation mechanisms (not shown) including a brake and an accelerator, and various sensor groups 180, like the vehicle 100 shown in FIG. The power transmission mechanism 170 transmits power from the engine 110 as a power source to the drive wheels 160 (160L and 160R). The power transmission mechanism 170 includes a torque converter 120, a clutch 130, an automatic transmission (AT) 140, and a drive shaft 150 (drive shaft or propeller shaft).

  Various sensors 180 include a brake sensor 181, an accelerator opening sensor 182, a wheel speed sensor 183, a shift position sensor 184 (for example, an inhibitor switch), and a turbine runner 122 (which is an output shaft of the torque converter 120). A turbine rotation speed sensor 185 that detects the rotation speed is included. That is, the various sensor groups 180 constitute detection means included in the present control means.

  The vehicle 100 further includes an electronic control unit (ECU) 190 that controls the engine 110 and the power transmission mechanism 170 based on various signals obtained from the operation mechanism and various sensor groups 180. The ECU 190 shown in FIG. 1 includes an engine control unit (E-ECU) 191, an automatic transmission control unit (T-ECU) 192, and a control circuit 193 (for controlling the automatic transmission 140 and the clutch 130). This control device is implemented as a T-ECU 192. That is, various processes executed by the release command unit, the release speed ratio calculation unit, the target command value update unit, and the like provided in the neutral control execution unit provided in the present control device are data storage devices (not shown) provided in the T-ECU 192. This is realized by a CPU (not shown) that executes various arithmetic processes according to a computer program stored in the computer.

  FIG. 1B is a schematic diagram illustrating a schematic configuration of the power transmission mechanism 170. As shown in FIG. 1B, the driving force generated from the engine 110 includes a pump impeller 121 that is an input shaft of the torque converter 120, a turbine runner 122 that is an output shaft of the torque converter 120, and a clutch 130. Then, it is transmitted to the drive wheel 160 via the automatic transmission 140 and the drive shaft 150.

  This control device is applied to a power transmission device including a hydraulic clutch 130. That is, the present control device controls the degree of engagement of the clutch 130 by increasing or decreasing the hydraulic pressure for engaging the hydraulic clutch 130. Therefore, in this control apparatus, the engagement command value for controlling the degree of engagement of the hydraulic clutch 130 is the hydraulic pressure command pressure.

  Further, in the vehicle 100, the neutral control execution means releases the clutch 130 to a neutral state when a predetermined neutral control execution condition is satisfied even when the shift position detected by the shift position sensor 184 is in the D range. Perform neutral control. In the present control device, the vehicle speed detected by the wheel speed sensor 183 is less than the predetermined second speed, the accelerator opening detected by the accelerator opening sensor 182 is less than the predetermined first opening, and the brake is applied. The neutral control execution condition is satisfied when the state detected by the sensor 181 that the brake is operating continues for a predetermined first time or longer.

  In the above case, the neutral control execution means adjusts the engagement command value, which is a command value for adjusting the degree of engagement, which is the degree of engagement of the clutch 130 for intermittently transmitting power in the power transmission mechanism 170, Neutral control is performed to bring the clutch 130 into the neutral state. On the other hand, the neutral control execution means stops the execution of the neutral control when any one of these conditions is not satisfied.

(Basic operation)
Here, the basic operation in the running neutral control executed by the neutral control executing means provided in the present control device will be described more specifically while comparing with the neutral control during stopping.

<Neutral control when stopped>
First, the neutral control during stop will be described. FIG. 2 is a schematic time chart showing an example of changes in the vehicle speed V, the brake operation, the engagement command value, and various rotational speeds in the neutral control at the time of stopping. The various rotational speeds include the rotational speed of the engine 110 as the power source (engine rotational speed Ne), the rotational speed of the turbine runner 122 (turbine rotational speed Nt) as the output shaft of the torque converter 120, and the automatic transmission 140. The rotational speed of the input shaft (input shaft rotational speed Nin) is included.

  First, at time t0, the brake is activated (turned ON) by the operation of the driver of the vehicle 100, and the traveling speed (vehicle speed V) of the vehicle 100 starts to decrease. Along with this, the input shaft rotation speed Nin also starts to decrease. At this time, the accelerator opening detected by the accelerator opening sensor 182 is less than a predetermined first opening (not shown). As a result, the engine rotational speed Ne also starts to decrease at time t0.

  At time t1, the vehicle speed V becomes 0 (zero), and the vehicle 100 stops. At this time, the brake is still operating (ON), and the accelerator opening remains below the predetermined first opening (not shown). Further, the engine rotational speed Ne is an idle rotational speed, and the input shaft rotational speed Nin is also 0 (zero). This state continues from time t1 to time t2 when a predetermined first time has elapsed. That is, the neutral control execution condition is satisfied. Therefore, at the time t2, execution of the neutral control at the time of stop is started.

  In order to release the hydraulic clutch 130 that has been in the engaged state so far, the engagement command value that is the hydraulic command pressure is reduced. Specifically, the engagement command value is lowered to a value corresponding to the degree of engagement immediately before the clutch 130 starts to be released, and then gradually lowered (sweep down). At the time t3, the turbine rotation speed Nt that has been consistent with the input shaft rotation speed Nin until then deviates from the input shaft rotation speed Nin and starts to increase. That is, the release of the clutch 130 has started at time t3. As described above, the degree of engagement of the clutch 130 is gradually lowered by sweeping down the engagement command value, so that the clutch 130 can be released while suppressing the occurrence of an impact due to a sudden change in driving force.

  Thereafter, the engagement command value for the clutch 130 is feedback-controlled so that the turbine rotational speed Nt matches a predetermined target value. The target value of the turbine rotational speed Nt is obtained, for example, by a preliminary adaptation experiment or the like when the degree of engagement of the clutch 130 is appropriate and the engine rotational speed Ne is the idle rotational speed. As appropriate. The appropriate degree of engagement of the clutch 130 is not so low that, for example, the execution condition of the neutral control at the time of stopping is not satisfied and the response when the clutch 130 is reengaged is deteriorated, and the engine 110 is caused by a creep phenomenon. The degree of engagement is not so high as to cause a load on the (power source) and cause deterioration of fuel consumption.

  Thereafter, at time t4, the operation of the brake is stopped by the operation of the driver of the vehicle 100 (OFF). As a result, the execution condition of the neutral control at the time of stopping is not satisfied, so the execution of the neutral control at the time of stopping is stopped, the clutch 130 is engaged as the engagement command value increases, and the turbine rotational speed Nt is input. It corresponds to the shaft rotation speed Nin. Thereafter, the engine rotation speed Ne, the turbine rotation speed Nt, the input shaft rotation speed Nin, and the vehicle speed V are increased by increasing the accelerator opening (not shown).

<Neutral control during driving>
Next, traveling neutral control executed by the present control device will be described. FIG. 3 is a schematic time chart showing an example of changes in the vehicle speed V, the brake operation, the engagement command value, and various rotational speeds in the neutral control during traveling. As in FIG. 2, the various rotational speeds include the rotational speed of the engine 110 as a power source (engine rotational speed Ne) and the rotational speed of the turbine runner 122 as the output shaft of the torque converter 120 (turbine rotational speed Nt). And the rotational speed of the input shaft of the automatic transmission 140 (input shaft rotational speed Nin).

  First, at time t0, the brake is activated (turned ON) by the operation of the driver of the vehicle 100, and the traveling speed (vehicle speed V) of the vehicle 100 starts to decrease. Along with this, the input shaft rotation speed Nin also starts to decrease. At this time, the accelerator opening detected by the accelerator opening sensor 182 is less than a predetermined first opening (not shown). As a result, the engine rotational speed Ne also starts to decrease at time t0. However, in the example shown in FIG. 3, the vehicle speed V and various rotational speeds decrease more slowly than in FIG. 2.

  At time t1, the vehicle speed V continues to decrease and is less than the predetermined second speed (V2). At this time, the brake is still operating (ON), and the accelerator opening remains below the predetermined first opening (not shown). As a result, the engine rotational speed Ne and the input shaft rotational speed Nin also continue to decrease. This state continues from time t1 to time t2 when a predetermined first time has elapsed. That is, the neutral control execution condition is satisfied.

  For example, the second speed V2 can be appropriately determined as a speed corresponding to a vehicle speed V that is sufficiently low to prevent a safety problem from occurring when the vehicle 100 travels even when neutral control is executed. For example, the first opening can be appropriately determined as an opening corresponding to an operation amount of an accelerator pedal that is assumed when the driver of the vehicle 100 is not trying to accelerate the vehicle 100. In the first time, for example, the vehicle speed V is less than the second speed V2, the accelerator opening is less than the first opening, and the state where the brake is operating is not temporarily generated but stable. The time can be appropriately determined as a sufficiently long time for determining that the time has continued.

  Since the vehicle speed V at time t2 is greater than the predetermined first speed (V1), the release command section provided in the neutral control execution means starts executing the neutral control during travel. Specifically, the engagement command value, which is a hydraulic pressure command, is reduced to release the hydraulic clutch 130 that has been engaged until now. The engagement command value at this time is not swept down as in the above-described neutral control at the time of stopping, but is reduced to a predetermined target engagement command value at a stretch and maintained constant at this target engagement command value. Is done. This step is executed by the “release command unit” described above. Note that the engagement command value is gradually decreased in a very short period immediately after time t2, but this is a measure for avoiding so-called "overshoot" and does not correspond to sweep-down in the neutral control when the vehicle is stopped. .

  As described above, the first speed V1 is a threshold value of the vehicle speed V as a determination criterion for switching whether or not the release command unit executes the running neutral control. Typically, the first speed V1 is 0 (zero) km / h. However, the first speed V1 may be set to a value slightly larger than 0 (zero) km / h in consideration of the detection accuracy of the vehicle speed V by the detection means. The release command unit may be configured to execute the neutral control at the time of stopping as described above when the vehicle speed V when starting the neutral control is equal to or lower than the first speed V1.

  On the other hand, after time t2, the brake is still operating (ON), and the accelerator opening remains below the predetermined first opening (not shown). As a result, the engine rotational speed Ne and the input shaft rotational speed Nin also continue to decrease.

  However, at the time t3, the turbine rotation speed Nt that has been decreasing with the input shaft rotation speed Nin until then is deviated from the input shaft rotation speed Nin and turned up. That is, the release of the clutch 130 has started at time t3. As described above, as the vehicle speed V decreases, the turbine rotation speed Nt gradually decreases (the input shaft rotation speed Nin and), the speed ratio of the torque converter 120 decreases, and the input torque to the clutch decreases. This is due to the gradual increase. As a result, also in this case, the clutch 130 can be gradually released while suppressing the occurrence of an impact due to a sudden change in the driving force.

  Thereafter, similarly to the above-described neutral control at the time of stopping, the engagement command value for the clutch 130 is feedback-controlled so that the turbine rotational speed Nt matches the predetermined target value. Thereafter, at time t4, the operation of the brake is stopped (turned off) by the operation of the driver of the vehicle 100. Along with this, since the execution condition of the running neutral control is no longer satisfied, the running neutral control is stopped, and the normal running state is restored in the same manner as the stopped neutral control.

(Learn target engagement command value in neutral control during travel)
In the above-described neutral control during travel, in the state where the engagement command value, which is the command pressure of the hydraulic pressure to the hydraulic clutch 130, is kept constant at the predetermined target engagement command value, as the vehicle speed V decreases, the clutch Input torque gradually increases, and eventually the clutch 130 is released.

  At this time, if the target engagement command value (in this case, the command pressure of the hydraulic pressure to the hydraulic clutch 130) is too low, the degree of engagement of the clutch 130 becomes excessively low. As a result, the time when the clutch 130 starts to be released is advanced, while the time required for making the turbine rotation speed Nt coincide with a predetermined target value after releasing and making the degree of engagement of the clutch 130 appropriate becomes longer. In some situations, the running neutral control execution condition is not satisfied, and the response when the clutch 130 is reengaged may be deteriorated.

  On the other hand, when the target engagement command value is too high, the degree of engagement of the clutch 130 becomes excessively high. As a result, the time when the release of the clutch 130 starts is delayed, and the period during which the load is applied to the engine 110 (power source) due to the creep phenomenon becomes longer, which may cause the fuel consumption of the vehicle 100 to deteriorate.

  Therefore, the present control device learns a target engagement command value that can make the degree of engagement appropriate when the release of the clutch 130 starts. Specifically, in the neutral control execution means provided in the present control device, as described above, when the vehicle speed V when the release command unit starts the neutral control is greater than the first speed V1, the engagement command value is set. The engagement degree of the clutch 130 is lowered while maintaining a predetermined target engagement command value constant. When the disengagement speed ratio calculation unit starts releasing the clutch based on the turbine rotation speed Nt and the engine rotation speed Ne when the turbine rotation speed Nt that has decreased with the decrease in the vehicle speed V starts to increase. The release speed ratio that is the speed ratio of the torque converter 120 is calculated. Further, the target engagement command value update unit corrects the target engagement command value based on the difference between the release speed ratio and the target speed ratio.

  The disengagement speed ratio calculation unit disengages the clutch 130 based on the turbine rotation speed Nt and the engine rotation speed Ne when the turbine rotation speed Nt that has been decreasing with the decrease in the vehicle speed V starts to increase as described above. The release speed ratio, which is the speed ratio of the torque converter 120 at the time when the operation starts, is calculated. Here, the calculation of the release speed ratio will be described in more detail. FIG. 4 is a partially enlarged view of the time chart showing the running neutral control shown in FIG.

  As described above, the release of the clutch 130 starts at time t3, and the turbine rotational speed Nt, which has been decreasing with the input shaft rotational speed Nin until then, deviates from the input shaft rotational speed Nin and starts to increase ( (See white circle A in FIG. 4). The engine rotational speed Ne at this time is constant at the idle rotational speed (see the black circle B in FIG. 4). The release speed ratio e, which is the speed ratio of the torque converter 120 when the release of the clutch 130 starts, is the engine speed Ne (black circle) of the turbine speed Nt (white circle A) at time t3. It can be calculated as a ratio to B) (e = Nt / Ne).

  The target engagement command value update unit corrects the target engagement command value based on the difference between the release speed ratio e calculated as described above and a predetermined target speed ratio et. Specifically, the target engagement command value update unit is configured to release the release speed when the release command unit maintains the clutch engagement command value constant at the target engagement command value to reduce the degree of clutch engagement. The target engagement command value is corrected so that the ratio e approaches the target speed ratio et.

  More specifically, when the release speed ratio e is excessive with respect to the target speed ratio et, the target engagement command value update unit updates the target engagement command value so that the degree of engagement of the clutch 130 becomes larger. (The target value of the indicated hydraulic pressure for the hydraulic clutch 130 is increased as indicated by the black arrow in FIG. 4). On the other hand, when the release speed ratio e is too small with respect to the target speed ratio et, the target engagement command value update unit corrects the target engagement command value so that the degree of engagement of the clutch 130 becomes smaller ( As shown by the white arrow in FIG. 4, the target value of the indicated hydraulic pressure for the hydraulic clutch 130 is reduced).

  The target speed ratio et is the speed ratio of the torque converter 120 when the degree of engagement of the clutch 130 is appropriate when the clutch 130 starts to be released, and can be determined as appropriate by, for example, a preliminary adaptation experiment. The appropriate degree of engagement when the clutch 130 starts to be released is, for example, the time required to make the degree of engagement of the clutch 130 appropriate by matching the turbine rotational speed Nt to a predetermined target value after the clutch 130 is released. The clutch 130 is not too low to be excessively long, and the engagement degree is not too high so that the period during which the release of the clutch 130 is delayed and the load is applied to the engine 110 (power source) due to the creep phenomenon is excessively long. Indicates the degree of engagement.

  In this control apparatus, “the difference between the release speed ratio e and the target speed ratio et” is “the difference between the release speed ratio e and the target speed ratio et”. That is, the neutral control execution means indicates that the target engagement command value update unit determines that the degree of engagement of the clutch 130 is greater when the difference obtained by subtracting the target speed ratio et from the release speed ratio e is greater than a predetermined first upper limit value. When the target engagement command value is corrected to be larger and the difference obtained by subtracting the target speed ratio et from the release speed ratio e is smaller than a predetermined first lower limit value, the degree of engagement of the clutch 130 is smaller. In this way, the target engagement command value is corrected.

  The first upper limit value is, for example, the turbine rotation speed Nt and the engine by the detection means provided in the present control device so that it can be determined whether or not the release speed ratio e is significantly larger than the target speed ratio et. It can be determined as appropriate in consideration of the detection accuracy of the rotational speed Ne. For example, the first lower limit value is set so that it is possible to determine whether the release speed ratio e is significantly smaller than the target speed ratio et. It can be determined as appropriate in consideration of detection accuracy and the like. The first upper limit value and the first lower limit value are a positive value and a negative value, respectively, and the absolute values thereof may be the same value or different values.

  Next time, when the release command unit keeps the clutch engagement command value constant at the target engagement command value and decreases the degree of clutch engagement, the target engagement command value corrected as described above is used. Used by the release command. Thereby, the present control device can learn a target engagement command value for releasing the clutch 130 with an appropriate degree of engagement in the running neutral control. In other words, the control device learns the target engagement command value for the clutch 130 even in the running neutral control, thereby suppressing the occurrence of an impact due to a sudden change in the driving force even when there is an individual difference in the clutch 130. However, it is possible to release the clutch 130 and achieve the released state (neutral state) of the clutch 130 with an appropriate degree of engagement as quickly as possible.

(Modification)
In the control device for the power transmission mechanism according to the embodiment of the present invention, as described above, the “difference between the release speed ratio e and the target speed ratio et” is set as the “difference between the release speed ratio and the target speed ratio”. The engagement command value update process was executed. However, as described above, the “ratio of the release speed ratio e to the target speed ratio et” may be “the difference between the release speed ratio and the target speed ratio”.

  That is, the target engagement command value update unit provided in the neutral control execution means has a greater degree of engagement of the clutch 130 when the ratio of the release speed ratio e to the target speed ratio et is greater than a predetermined second upper limit value. When the ratio of the release speed ratio e to the target speed ratio et is smaller than a predetermined second lower limit value, the target engagement command value is corrected so that the degree of engagement of the clutch 130 becomes smaller. It may be configured to correct the combined command value.

  For example, detection of the turbine rotation speed Nt and the engine rotation speed Ne by the detection unit is performed so that the second upper limit value can determine whether or not the release speed ratio e is significantly larger than the target speed ratio et. It can be determined as appropriate in consideration of accuracy and the like. For example, detection of the turbine rotational speed Nt and the engine rotational speed Ne by the detecting means is performed so that the second lower limit value can determine whether or not the release speed ratio e is significantly smaller than the target speed ratio et. It can be determined as appropriate in consideration of accuracy and the like. The second upper limit value and the second lower limit value are values larger than 1 and values smaller than 1, respectively.

  Furthermore, the configuration of the vehicle to which the device of the present invention is applied is not particularly limited, and is not limited to the above embodiment as long as it has a power source, driving wheels, an accelerator, and a brake. The power source is not limited to one having a specific configuration, and specific examples include internal combustion engines such as gasoline engines and diesel engines, and prime movers such as electric motors (motors). The drive wheels are not particularly limited as long as the vehicle can travel by transmitting the power transmitted from the power source to the road surface. Specific examples of the drive wheel include wheels such as tires.

  In the above, for the purpose of explaining the present invention, several embodiments and modifications having specific configurations have been described with reference to the accompanying drawings. However, the scope of the present invention is not limited to these illustrative examples. It should be understood that the present invention should not be construed as being limited to the embodiments and the modifications, and that appropriate modifications can be made within the scope of the matters described in the claims and the specification.

  DESCRIPTION OF SYMBOLS 100 ... Vehicle, 110 ... Engine, 120 ... Torque converter, 121 ... Pump impeller, 122 ... Turbine runner, 130 ... Clutch, 140 ... Automatic transmission, 150 ... Drive shaft, 160, 160L and 160R ... Drive wheel, DESCRIPTION OF SYMBOLS 170 ... Power transmission mechanism, 180 ... Various sensor groups, 181 ... Brake sensor, 182 ... Accelerator opening sensor, 183 ... Wheel speed sensor, 184 ... Shift position sensor, 185 ... Turbine rotational speed sensor, 190 ... Electronic control device ( ECU), 191 ... engine control unit (E-ECU), and 192 ... automatic transmission control unit (T-ECU).

Claims (1)

Applied to a power transmission mechanism for transmitting power from the power source to the driving wheel in a vehicle having a power source, driving wheel, accelerator and brake;
When a predetermined neutral control execution condition is satisfied, an engagement command value that is a command value for adjusting an engagement degree that is a degree of engagement of a clutch that interrupts transmission of power in the power transmission mechanism is adjusted. Neutral control execution means for performing neutral control to bring the clutch into a neutral state;
Engine rotational speed that is the rotational speed of the power source, turbine rotational speed that is the rotational speed of the turbine runner of the torque converter that transmits the power from the power source to the clutch in the power transmission mechanism, and traveling of the vehicle Detection means for detecting the vehicle speed, which is a speed;
Comprising
A control device for a power transmission mechanism,
The neutral control execution means maintains the engagement command value constant at a predetermined target engagement command value when the vehicle speed at the start of the neutral control is higher than a predetermined first speed. A release command section for lowering the degree of engagement;
The speed ratio of the torque converter when the release of the clutch starts based on the turbine rotational speed and the engine rotational speed when the turbine rotational speed that has been lowered due to the decrease in the vehicle speed starts to increase. A release speed ratio calculation unit for calculating a release speed ratio,
A target engagement command value update unit for correcting the target engagement command value based on a difference between the release speed ratio and a predetermined target speed ratio;
Comprising
Control device for power transmission mechanism.

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