JP5359966B2 - Vehicle drive system - Google Patents

Description

  The present invention relates to a vehicle drive system, and more particularly to a vehicle drive system that can improve responsiveness during re-acceleration after deceleration of a brake.

  A typical vehicle drive system includes a transmission that changes the gear position by switching engagement and disengagement of a friction engagement element. As a conventional vehicle drive system having such a configuration, a technique described in Patent Document 1 is known.

JP 2008-051254 A

  Here, when re-acceleration after deceleration by depressing the brake, (1) the driver performs the operation of switching from the brake to the accelerator, and (2) the downshift is performed when the accelerator depressing amount exceeds the predetermined downshift change line. (3) After the prescribed time has elapsed, a downshift is started and hydraulic control for driving the friction engagement element is performed, and then (4) the shift proceeds. The downshift is complete. As a result, the acceleration desired by the driver is generated. Therefore, the shorter the required times of (1) to (4), the better the responsiveness at the time of reacceleration is preferable.

  However, the conventional vehicle drive system has a problem that the responsiveness at the time of reacceleration after deceleration of the brake is poor.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a vehicle drive system that can improve the responsiveness at the time of reacceleration after brake deceleration.

In order to achieve the above object, a vehicle drive system according to the present invention is a vehicle drive system including a transmission that switches engagement and disengagement of a friction engagement element to change a gear position, and at a brake release speed. Re-acceleration request estimation means for estimating the possibility of a re-acceleration request after brake deceleration based on, and preliminary operation control means for controlling a predetermined preliminary operation for engagement or release of the friction engagement element, and When the vehicle is decelerated, the reacceleration request estimating means re-accelerates from a plurality of different downshift destination gears based on a comparison result between a plurality of different threshold values and the brake release speed. estimating one or more gear stages is selected by the request, the preliminary operation control means either to one or more gear stages of the preliminary operation is the estimation for the downshift Characterized in that to perform only the frictional engagement elements that.

  In this vehicle drive system, the driver is required to perform re-acceleration after deceleration of the brake, so that the preliminary engagement for downshifting is performed by the frictional engagement element for a predetermined shift stage. Time is shortened. Thereby, there is an advantage that the responsiveness at the time of reacceleration accompanying the downshift is improved.

  In the vehicle drive system according to the present invention, the reacceleration request estimating means determines the possibility of the reacceleration request using at least one of brake release speed, navigation information, and forward vehicle information.

  In this vehicle drive system, there is a possibility that the reacceleration request estimation means may request a reacceleration (and a shift stage selected at the time of reacceleration) using at least one of brake release speed, navigation information, and forward vehicle information. May be determined. Accordingly, there is an advantage that the preliminary downshift control can be appropriately performed according to the traveling scene.

  In the vehicle drive system according to the present invention, the preliminary gear for the downshift is made to be performed by the friction engagement element for a predetermined shift stage in a situation where the driver requests reacceleration after brake deceleration. The time required for control is shortened. Thereby, there is an advantage that the responsiveness at the time of reacceleration accompanying the downshift is improved.

FIG. 1 is a configuration diagram showing a vehicle drive system according to an embodiment of the present invention. FIG. 2 is a skeleton diagram showing a torque converter and a transmission of the vehicle drive system shown in FIG. FIG. 3 is an operation engagement table showing the operation of the friction engagement element of the transmission shown in FIG. FIG. 4 is a flowchart showing preliminary operation control of downshift. FIG. 5 is a time chart showing a specific example of the preliminary operation control described in FIG. FIG. 6 is a flowchart showing a modification of the preliminary operation control described in FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Vehicle drive system]
The vehicle drive system 1 is a device that transmits engine power to an axle, and includes an engine 2, a torque converter 3, a transmission 4, and a control unit 5 (see FIGS. 1 and 2).

  The engine 2 is a power source that generates driving torque, and is constituted by, for example, an internal combustion engine. For example, in this embodiment, the engine 2 is composed of a known internal combustion engine having a fuel injection device, an intake / exhaust device, and an ignition device.

  The torque converter 3 is a device that transmits power by the kinetic energy of a fluid, and is composed of, for example, a fluid torque converter. The torque converter 3 includes an impeller 31, a turbine 32, a stator 33, and a lock-up clutch 34, and an output shaft of the engine 2 (for example, a crankshaft of an internal combustion engine) via a rotating shaft 11 on the input side. Connected to

  The transmission 4 is an automatic transmission mechanism that changes the transmission ratio, and is connected to the output shaft of the torque converter 3 via the rotary shaft 12 on the input side and to the axle via the rotary shaft 13 on the output side. Is done. The transmission 4 has a friction engagement element group to form a gear stage. For example, in this embodiment, the transmission 4 has a Simpson-type gear train structure, and has a pair of clutches C1 and C2 and a pair of brakes B1 and B2 as a friction engagement element group ( (See FIG. 2). In each of these friction engagement element groups, engagement and release are switched by operation control of a clutch pressure adjusting electromagnetic valve (not shown). In the transmission 4, the respective gear engagement stages C1, C2, B1, and B2 are engaged or released according to a predetermined operation engagement table (see FIG. 3), so that each gear stage is set. In the operation engagement table of FIG. 3, “◯” indicates that the corresponding friction engagement element is in the engaged state, and when blank, the corresponding friction engagement element is in the released state. It is shown that.

  The control unit 5 includes an ECU (Electronic Control Unit) 51 and various sensors 521 and 522. The ECU 51 includes a transmission ratio control unit 511, a brake release speed calculation unit 512, a reacceleration request estimation unit 513, a preliminary operation control unit 514, and a storage unit 515. The gear ratio control unit 511 controls the gear ratio of the transmission 4. The brake release speed calculation unit 512 calculates a brake release speed described later. The reacceleration request estimation unit 513 estimates the possibility of a reacceleration request after brake deceleration based on the brake release speed. The preliminary motion control unit 514 controls a predetermined preliminary motion related to the engagement or release of the friction engagement elements C1, C2, B1, and B2. The storage unit 515 stores predetermined information used for control. The various sensors include, for example, a pedal stroke sensor 521 for detecting a brake operation amount, a brake pedal force sensor and a booster pressure sensor, an accelerator opening sensor 522 for detecting an accelerator opening, a throttle opening sensor for the engine 2, an engine rotation A number sensor, an oil pump speed sensor, and the like. In the control unit 5, the ECU 51 controls the engine 2, the torque converter 3, and the transmission 4 based on the output values of various sensors.

  In this vehicle drive system 1, the engine 2 generates drive torque, which is amplified by the torque converter 3 and input to the transmission 4 (see FIG. 2). The drive torque is shifted by the transmission 4 and output to the rotary shaft 13. Thereby, the drive torque from the engine 2 is transmitted to the axle of the vehicle, and the vehicle travels.

  In the transmission ratio control of the transmission 4, the ECU 51 (transmission ratio control unit 511) selects the transmission speed of the transmission 4 and sends a transmission signal (clutch pressure regulation signal) to each friction engagement element C 1, C 2, B 1. , B2 to change the gear position and change the gear ratio. At this time, for example, the gear position is selected based on the output torque of the engine 2, the engine speed, the oil pump speed, the brake operation amount of the driver, the accelerator opening, and the like. The output torque of the engine 2 is estimated from, for example, the throttle opening, the intake air amount, the fuel injection amount, the ignition timing, and the like. Further, the brake operation amount can be calculated based on output values of a pedal stroke sensor 521, a brake pedal force sensor, a booster pressure sensor, and the like, for example. The accelerator opening is acquired as an output value of the accelerator opening sensor 522, for example.

[Preliminary operation control of downshift]
Normally, when reaccelerating after deceleration by depressing the brake, (1) the driver performs an operation of switching from the brake to the accelerator, and (2) a downshift is performed when the accelerator depressing amount exceeds a predetermined downshift change line. (3) The downshift is started after the lapse of the specified time, and the hydraulic control for driving the friction engagement element is performed. Then, (4) the shift is advanced and the downshift is performed. The shift is complete. As a result, the acceleration desired by the driver is generated. Therefore, the shorter the required times of (1) to (4), the better the responsiveness at the time of reacceleration is preferable.

  Here, under the situation where the driver requests re-acceleration after deceleration of the brake, it can be determined that the urgent re-acceleration is required as the switching operation from the brake to the accelerator is faster. If re-acceleration is delayed under such circumstances, the driver's feeling of hesitation increases, which is not preferable. On the other hand, under such circumstances, the brake release speed by the driver tends to be faster than normal.

  Therefore, in this vehicle drive system 1, when there is a possibility of a request for re-acceleration after brake deceleration at the time of brake deceleration of the vehicle, a frictional engagement element that applies a preliminary operation for downshift to a predetermined gear stage. The control to be performed (downshift preliminary operation control) is performed. Thereby, the responsiveness at the time of reacceleration of the vehicle accompanying a downshift improves. This preliminary downshift control is performed as follows (see FIG. 4). Here, a case will be described in which when the vehicle is decelerated and the brake pedal is switched to the accelerator pedal, the speed of the transmission 4 is downshifted from the third speed to a predetermined speed and reaccelerated. .

  In step ST101, it is determined whether or not the brake is ON when the vehicle is traveling. That is, it is determined whether or not deceleration due to depression of the brake pedal is being performed. For example, in this embodiment, the ECU 51 makes this determination based on the output value of the vehicle speed sensor and the brake operation amount of the brake pedal. If an affirmative determination is made in step ST101, the process proceeds to step ST102, and if a negative determination is made, the process ends (returns to step ST101).

  In step ST102, the brake release speed Dltbrkoff is calculated. The brake release speed Dltbrkoff is a speed at which the driver depresses the brake pedal, and it can be determined that urgent reacceleration is required as the speed increases. For example, in this embodiment, the ECU 51 (brake release speed calculation unit 512) calculates the brake release speed Dltbrkoff based on the rate of change of the brake operation amount of the brake pedal. Note that the brake operation amount can be calculated based on output values of a pedal stroke sensor 521, a brake pedal force sensor, a booster pressure sensor, and the like. After step ST102, the process proceeds to step ST103.

  In step ST103, it is determined whether or not the brake release speed Dltbrkoff is equal to or higher than a predetermined threshold value X1 (reacceleration request estimation step). That is, based on the brake release speed Dltbrkoff, the possibility of a request for re-acceleration after brake deceleration (the driver's intention to accelerate) is determined. For example, in this embodiment, the ECU 51 (reacceleration request estimation unit 513) compares the brake release speed Dltbrkoff with a predetermined threshold value X1 stored in the storage unit 515, and performs this determination step ST103. If an affirmative determination is made in step ST103, the process proceeds to step ST104, and if a negative determination is made, the process proceeds to step ST108.

  In step ST104, a preliminary operation for downshifting the gear position of the transmission 4 from the third speed to the first speed is performed (preliminary operation step). That is, when the brake release speed Dltbrkoff is equal to or higher than the predetermined threshold value X1 (positive determination in step ST103), there is a high possibility that urgent and large acceleration is required after brake deceleration. Therefore, a preliminary downshift operation is performed for the predicted shift speed. Here, since it can be predicted that a downshift from the third speed to the first speed will be performed, preliminary hydraulic pressure supply to the brake B1 (see FIG. 3) that forms the first gear is started. At this time, the hydraulic pressure of the brake B1 is set within a range in which the brake B1 is not engaged (preferably held in a state immediately before the engaged state). In the preliminary operation, the ECU 51 (preliminary operation control unit 514) outputs a preliminary operation signal to the clutch pressure regulating electromagnetic valve of the transmission 4, whereby preliminary hydraulic pressure is supplied to the brake B1. After step ST104, the process proceeds to step ST105.

  In step ST105, it is determined whether or not a shift command to the first speed has been issued within a predetermined period T from the start of the preliminary operation (step ST104). For example, in this embodiment, the preliminary operation control unit 514 of the ECU 51 acquires a shift signal from the transmission ratio control unit 511 to the transmission 4, and a shift signal related to a shift command to the first speed within a predetermined period T. It is determined whether or not is output. If an affirmative determination is made in step ST105, the process proceeds to step ST106, and if a negative determination is made, the process proceeds to step ST107.

  In step ST106, gear ratio control for downshifting the gear position of the transmission 4 from the third speed to the first speed is performed. Specifically, the ECU 51 (transmission ratio control unit 511) outputs a shift signal to the clutch pressure regulating electromagnetic valve of the transmission 4, whereby the hydraulic pressure is supplied to the clutch C2 and the brake B1, and the shift stage is switched. Is performed (see FIG. 3). At this time, since the downshift preliminary operation (step ST104) is performed in the friction engagement elements C2 and B1 of the corresponding gear stage, surge control (quick apply control) for filling the hydraulic oil is unnecessary. Become. As a result, the time required for the gear ratio control (the time from the shift command for the downshift to the completion of the shift stage change) is significantly reduced. After this step ST106, the process is terminated.

  In step ST107, the downshift preliminary operation (step ST104) is canceled. That is, if the predetermined period T has elapsed since the start of the preliminary operation but there is still no gear shift command to the first gear (output of the gear shift signal from the gear ratio control unit 511 to the clutch pressure regulating solenoid valve) Re-acceleration is not expected. There may also be a shift command to a shift stage other than the first speed. Therefore, if a negative determination is made in step ST105, the preliminary downshift operation is canceled. After this step ST107, the process is terminated. Note that when a shift command for downshifting is issued after the preliminary operation is canceled, the gear ratio control is performed as usual (no preliminary operation).

  In step ST108, it is determined whether or not the brake release speed Dltbrkoff is equal to or higher than a predetermined threshold value X2 (reacceleration request estimation step). For example, in this embodiment, the ECU 51 (re-acceleration request estimation unit 513) compares the brake release speed Dltbrkoff with a predetermined threshold value X2 stored in the storage unit 515, and performs this determination step ST108. If an affirmative determination is made in step ST108, the process proceeds to step ST109, and if a negative determination is made, the process ends. That is, when the brake release speed Dltbrkoff is slow (Dltbrkoff <X2, negative determination in step ST108), it is considered that rapid re-acceleration is not necessary, and thus the process ends.

  In step ST109, a preliminary operation for downshifting the gear position of the transmission 4 from the third speed to the second speed is performed (preliminary operation step). That is, when the brake release speed Dltbrkoff is in the range of X2 ≦ Dltbrkoff <X1 (negative determination in step ST103 and positive determination in step ST108), an acceleration that is urgent after brake deceleration but is not so large is required. Probability is high. Therefore, a preliminary downshift operation is performed for the predicted shift speed. Here, since it can be predicted that a downshift from the third speed to the second speed will be performed, preliminary hydraulic pressure supply to the brake B2 (see FIG. 3) forming the second speed gear stage is started. At this time, the hydraulic pressure to the brake B2 is set within a range where the brake B2 is not engaged (preferably held in a state immediately before the engaged state). In the preliminary operation, the ECU 51 (preliminary operation control unit 514) outputs a preliminary operation signal to the clutch pressure regulating electromagnetic valve of the transmission 4, whereby preliminary hydraulic pressure is supplied to the brake B2. After step ST109, the process proceeds to step ST110.

  In step ST110, it is determined whether or not a shift command to the second speed has been issued within a predetermined period T from the start of the preliminary operation (step ST109). For example, in this embodiment, the preliminary operation control unit 514 of the ECU 51 acquires a shift signal from the transmission ratio control unit 511 to the transmission 4, and a shift signal applied to a shift command to the second speed within a predetermined period T. It is determined whether or not is output. If an affirmative determination is made in step ST110, the process proceeds to step ST111. If a negative determination is made, the process proceeds to step ST112.

  In step ST111, gear ratio control for downshifting the gear position of the transmission 4 from the third speed to the second speed is performed. Specifically, the ECU 51 (speed ratio control unit 511) outputs a shift signal to the clutch pressure regulating electromagnetic valve of the transmission 4, whereby the hydraulic pressure is supplied to the clutch C2 and the brake B2, and the shift stage is switched. Is performed (see FIG. 3). At this time, since the preliminary downshift operation (step ST109) is performed in the corresponding frictional engagement elements C2 and B2, the surge control for filling the hydraulic oil becomes unnecessary. Thereby, the time required for the gear ratio control is greatly shortened. After this step ST111, the process is terminated.

  In step ST112, the preliminary downshift operation (step ST109) is canceled. That is, it is considered that sudden re-acceleration is not performed when a predetermined period T has elapsed since the start of the preliminary operation but there is still no gear shift command to the second speed. There may also be a shift command to a shift stage other than the second speed. Therefore, if a negative determination is made in step ST110, the downshift preliminary operation is canceled. After this step ST112, the process is terminated. Note that when a shift command for downshifting is issued after the preliminary operation is canceled, the gear ratio control is performed as usual (no preliminary operation).

[Specific example of preliminary operation control of downshift]
FIG. 5 is a time chart showing a specific example of preliminary operation control of downshift. The figure shows a case where the speed of the transmission 4 is downshifted from the third speed to the first speed and re-accelerated when the vehicle is decelerated from the brake pedal to the accelerator pedal. . When traveling at the third speed, the clutches C1 and C2 of the transmission 4 are in an engaged state, and the brakes B1 and B2 are in a released state (see FIG. 3).

  First, when the vehicle is decelerated, the brake pedal is depressed and the brake signal (a) is ON (t = t0). Next, the brake pedal is rapidly returned to switch to the accelerator pedal (t = t1 to t3). At this time, the output value of the pedal stroke sensor 521 is acquired at a predetermined sampling interval, and the brake release speed (b) is calculated (step ST102). When the brake release speed (b) is equal to or greater than a predetermined threshold value X1, a preliminary operation for downshifting from the third speed to the first speed is started (affirmative determination in step ST103 and step ST104) (t = t2). . In this preliminary operation, preliminary hydraulic pressure is supplied to the brake B1 (see FIG. 3) that forms the first gear. At this time, the hydraulic pressure (f) of the brake B1 is set within a range where the brake B1 is not engaged (ON).

  Next, when the brake pedal is switched to the accelerator pedal, the accelerator opening (d) increases (t = t3 to t4). The accelerator opening (d) is acquired at a predetermined sampling interval. Then, based on the accelerator opening (d), a shift determination (c) is performed in which the gear position is downshifted from the third speed to the first speed, and the gear ratio control is started (affirmative determination in step ST105 and step ST106). ) (T = t4). Then, the hydraulic pressure (f) of the brake B1 increases and the brake B1 is engaged (ON), thereby completing the change of the gear ratio (t = t5).

  In FIG. 5, the embodiment shows a case in which the downshift preliminary operation control is performed. In the conventional example, the preliminary operation control is not performed, and the hydraulic pressure (f) of the brake B1 is supplied after the shift determination (c). Shows the case. As shown in the figure, it is understood that the time required for the gear ratio control is shortened by performing the downshift preliminary operation control, and the responsiveness at the time of reacceleration accompanying the downshift is improved.

[Modified example of preliminary operation control of downshift]
In this vehicle drive system 1, the possibility of a shift determination (selected gear stage) or a request for re-acceleration is estimated from the relationship between the brake release speed Dltbrkoff and predetermined threshold values X1 and X2 (step ST103 and step ST108). ) A downshift preliminary operation is performed only for the corresponding gear position (step ST104 and step ST109) (see FIG. 4). Such a configuration is preferable in that a sufficient and sufficient amount of hydraulic oil to be supplied to the frictional engagement elements C1, C2, B1, and B2 can be secured.

  However, the present invention is not limited to this, and when it is estimated that there is a high possibility of a request for re-acceleration after deceleration of the brake, a preliminary downshift operation may be performed for all the shift speeds to be downshifted. . This preliminary operation control is performed, for example, as follows (see FIG. 6).

  First, it is determined whether or not the brake is ON when the vehicle is running (step ST201). If the brake is ON, the brake release speed Dltbrkoff is calculated (step ST202), and the brake release speed Dltbrkoff is a predetermined threshold value. It is determined whether or not it is equal to or greater than X3 (reacceleration request estimation step ST203). These steps ST201 to ST203 are performed in the same manner as steps ST101 to ST103.

  Next, when the brake release speed Dltbrkoff is equal to or higher than the predetermined threshold value X3 (affirmative determination in step ST203), a preliminary downshift operation is performed for all the shift speeds to be shifted down (step ST204). . For example, when the brake is decelerated at the third speed, a downshift to the first speed or the second speed is assumed. Therefore, a preliminary downshift operation is performed for both the first and second gears. This preliminary operation is performed in the same manner as in step ST104.

  When a shift command to the first speed or the second speed is issued within a predetermined period T from the start of the preliminary operation (step ST204) (affirmative determination in step ST205 or affirmative determination in step ST208), the corresponding shift is performed. Downshift control to a gear is performed (step ST206 or step ST209), and the preliminary operation (step ST204) is canceled (step ST207 or step ST210) for other gears. If there is no shift command to the first speed or the second speed even after the predetermined period T has elapsed since the start of the preliminary operation, the preliminary operation (step ST204) of all the gears is canceled (step ST211). ).

  In such a configuration, since a predetermined preliminary operation (step ST204) is performed for all the shift speeds to be shifted down, the time required for the gear ratio control regardless of the shift down to any gear speed. Is shortened. Thereby, the responsiveness at the time of reacceleration accompanying a downshift is improved appropriately.

[When using navigation information]
Further, in the vehicle drive system 1, a reacceleration request (and a gear stage selected at the time of reacceleration) is estimated based on the brake release speed Dltbrkoff (step ST103 and step ST108) (see FIG. 4). Such a configuration is preferable in that the brake release speed Dltbrkoff can be obtained by using the configuration of an existing vehicle drive system (for example, the pedal stroke sensor 521), so that the reacceleration request can be easily estimated.

  However, the present invention is not limited to this. For example, the shift information or the reacceleration request may be estimated using the navigation information from the navigation device 7 (see FIG. 1). Further, the navigation information and the brake release speed Dltbrkoff may be used in combination. As a result, preliminary downshift control (step ST104 and step ST109) can be performed in accordance with the driver's intention to accelerate.

  In the case of using navigation information, for example, (1) what kind of acceleration is performed thereafter by comparing the current vehicle speed (output value of the vehicle speed sensor) and the speed limit (navigation information) of the traveling road. Is easy to estimate. For example, when the difference between the current vehicle speed and the speed limit is greater than or equal to a predetermined threshold (traveling speed is slow), there is a high possibility that a large acceleration is required thereafter. In addition, for example, (2) using the curvature information of the corner of the traveling road makes it easy to estimate what kind of acceleration will be performed thereafter. For example, when the curvature of the corner is small, there is a high possibility that a large acceleration is required at the corner exit after a large deceleration at the corner entrance. Therefore, in these cases, the responsiveness at the time of reacceleration accompanying the downshift can be improved by performing the downshift preliminary control (step ST104 and step ST109). When the re-acceleration requirement is low, the downshift preliminary control is omitted.

[When using radar sensors, etc.]
Further, not limited to the above, for example, information on the preceding vehicle is acquired by an information acquisition unit such as a radar sensor or a camera installed in front of the vehicle, and a shift determination or a reacceleration request is made based on this information (step ST103 and step ST ST108) may be estimated (not shown). Further, the shift determination or the reacceleration request may be estimated by using the information on the preceding vehicle and the brake release speed Dltbrkoff in combination, or using the information on the preceding vehicle and the navigation information. Thereby, the preliminary downshift control can be appropriately performed according to the driving scene.

  For example, when there is no preceding vehicle or the distance between the vehicle and the preceding vehicle is equal to or greater than a predetermined threshold (the distance between the vehicles is sufficiently long), there is a high possibility that a large acceleration is required thereafter. Therefore, in such a case, the responsiveness at the time of reacceleration accompanying the downshift can be improved by performing the downshift preliminary control (step ST104 and step ST109). On the other hand, when the inter-vehicle distance with the preceding vehicle is equal to or less than a predetermined threshold (the inter-vehicle distance is short), the downshift preliminary control is omitted.

[effect]
As described above, in this vehicle drive system 1, the reacceleration request estimation means (reacceleration request estimation unit 513) that estimates the possibility of a reacceleration request after brake deceleration based on the brake release speed Dltbrkoff, friction, Preliminary operation control means (preliminary operation control unit 514) for controlling a predetermined preliminary operation related to engagement or disengagement of the engagement elements C1, C2, B1, B2 is provided (see FIG. 1). When the vehicle is decelerated (affirmative determination in step ST101), when the reacceleration request estimation means determines that there is a possibility of a reacceleration request after deceleration of the brake (positive determination in step ST103 or positive determination in step ST108). ), The preliminary operation control means causes the friction engagement element applied to the predetermined shift stage to perform the preliminary operation for downshifting (step ST104 or step ST109) (see FIG. 4).

  In such a configuration, the time required for gear ratio control is shortened because the frictional engagement element for a predetermined gear stage performs a preliminary operation for downshifting in a situation where the driver requests reacceleration after deceleration of the brake. Is done. Thereby, there is an advantage that the responsiveness at the time of reacceleration accompanying the downshift is improved.

  Further, in this vehicle drive system 1, the reacceleration request estimating means estimates the gear stage selected by the reacceleration request after brake deceleration (step ST103 and step ST108), and the preliminary operation control means is the gear position. Only the frictional engagement element according to (2) performs a preliminary operation for downshift (step ST104 and step ST109) (see FIG. 4). In such a configuration, a shift stage for performing a preliminary operation is appropriately set according to the estimation result of the shift stage, and a downshift preliminary operation is performed only for that shift stage. Thereby, there is an advantage that unnecessary preliminary operation (use of hydraulic oil of the friction engagement element) can be prevented.

  Further, in this vehicle drive system 1, the preliminary operation control means causes the friction engagement elements for all the gears to be shifted down to perform the preliminary operation (step ST204) (see FIG. 6). In such a configuration, the time required for the gear ratio control is shortened when the shift down to any gear stage is performed. Thereby, there is an advantage that the response at the time of reacceleration accompanying the downshift is appropriately improved.

  Further, in this vehicle drive system 1, if there is no shift command to the gear stage that has performed the preliminary operation even after a predetermined period T has elapsed since the preliminary operation was started, the vehicle drive system 1 is switched to the gear stage that has performed the preliminary operation. Such preliminary operation is canceled (negative determination in step ST105 and step ST107, and negative determination in step ST110 and step ST112) (see FIG. 4). Thereby, there is an advantage that an unnecessary preliminary operation can be canceled.

  Similarly, when there is a shift command to a gear stage other than the gear stage that performed the preliminary operation, the preliminary operation related to the gear stage that performed the preliminary operation is canceled (determination of step ST105 and step ST107, And the negative determination of step ST110 and step ST112) (refer FIG. 4). Thereby, there is an advantage that an unnecessary preliminary operation can be canceled.

  Further, in this vehicle drive system 1, the reacceleration request estimation means determines the possibility of a reacceleration request (and the gear stage selected at the time of reacceleration) based on the brake release speed Dltbrkoff (step ST103 and Step ST108). In such a configuration, the brake release speed Dltbrkoff can be obtained using the configuration of the existing vehicle drive system (for example, the pedal stroke sensor 521), and thus there is an advantage that the reacceleration request can be easily estimated.

  Further, in the above configuration, the reacceleration request estimation means can make a reacceleration request (and a gear stage selected at the time of reacceleration) using at least one of the brake release speed Dltbrkoff, navigation information, and forward vehicle information. Sex may be determined. Accordingly, there is an advantage that the preliminary downshift control can be appropriately performed according to the traveling scene.

  As described above, the vehicle drive system according to the present invention is useful in that the responsiveness at the time of reacceleration after deceleration of the brake can be improved.

DESCRIPTION OF SYMBOLS 1 Vehicle drive system, 2 Engine, 3 Torque converter, 31 Impeller, 32 Turbine, 33 Stator, 34 Lockup clutch, 4 Transmission, 5 Control unit, 51 ECU, 511 Gear ratio control part, 512 Brake release speed calculation part 513 Reacceleration request estimation unit 514 Preliminary motion control unit 515 Storage unit 521 Pedal stroke sensor 522 Accelerator opening sensor 7 Navigation device 11-13 Rotating shaft

Claims (2)

A vehicle drive system including a transmission that changes a gear position by switching engagement and release of a friction engagement element,
Re-acceleration request estimation means for estimating the possibility of a re-acceleration request after brake deceleration based on the brake release speed;
Preliminary operation control means for controlling a predetermined preliminary operation for engagement or release of the friction engagement element, and
When the vehicle is decelerated, the reacceleration request estimation means determines the reacceleration request from a plurality of different downshift destination gears based on a comparison result between a plurality of different threshold values and the brake release speed. Estimating one or a plurality of shift speeds selected in
The vehicle drive system, wherein the preliminary operation control means causes the preliminary operation for downshifting to be performed only by the friction engagement element applied to the estimated one or more shift stages . The re-acceleration request estimating means brake release speed, the vehicle drive system of the placing serial to claim 1 determines the possibility of the re-acceleration request using at least one of navigation information and forward vehicle information.

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