JP5768188B2 - Control device and control method for automatic transmission - Google Patents

Description

  The present invention relates to a control device and a control method for an automatic transmission in a vehicle that stops and restarts a driving force source.

  Idle stop technology is widely used that stops the engine that is the driving force source when the vehicle is stopped to improve fuel efficiency. For the purpose of further improving the fuel performance, so-called coast stop control for stopping the engine before the vehicle stops, such as not only when the vehicle stops but also when decelerating, has been put into practical use.

  In an automatic transmission mounted on a vehicle, engagement of a friction element such as a clutch is controlled by hydraulic pressure. When the vehicle decelerates and stops, the friction element may be switched in preparation for re-acceleration and restart. On the other hand, when the engine is stopped during traveling, the oil pump driven by the engine cannot generate hydraulic pressure, so that the supply of hydraulic pressure for switching the friction element may decrease.

  As a control of such an automatic transmission, JP2006-170295A discloses that the engine is automatically stopped while the vehicle is running, the automatic transmission is set to the neutral state, and after the engine is stopped, the electric oil pump is operated to make the friction element. An apparatus that starts so-called precharge that supplies hydraulic pressure is disclosed.

  In JP2006-170295A, the automatic transmission is in the neutral state from the start of coast stop control to the start of idle stop control. A time lag occurs. Therefore, it is also possible to prepare for engagement by supplying any hydraulic pressure that does not have torque capacity to the friction element in the released state in preparation for the next shift while reducing the occurrence of time lag by setting any friction element in the engaged state. Conceivable.

  However, depending on the start timing of supplying hydraulic pressure to the friction element in the released state to prepare for fastening, the friction element in the fastening state slips, so that the torque is lost due to the slip or the fastening is accompanied by the re-fastening of the slipped friction element. A shock may change the longitudinal acceleration of the vehicle, which may cause the driver to feel uncomfortable.

  In other words, when the supply of hydraulic pressure to the released friction element is started in a state where the mechanical pump is not driven, the hydraulic pressure supplied to the automatic transmission decreases and the friction element in the engaged state slips, as described above. The driver may feel uncomfortable.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a control device for an automatic transmission that can reduce the uncomfortable feeling given to the driver by suppressing the slip of the friction element in the coast stop control. And

According to one embodiment of the present invention, the transmission ratio depends on the driving force source that drives the vehicle, the hydraulic source that is driven by the driving force source to generate hydraulic pressure, and the engagement state of the first friction element and the second friction element. A control device for an automatic transmission in a vehicle, comprising: a transmission that transmits the driving force of the driving force source to the driving wheels; and a control unit that controls the operation of the driving force source, the hydraulic source, and the transmission mechanism. Applied. The control unit outputs a stop command to the driving force source to stop the driving force source when the vehicle is in a running state, the first friction element is in the engaged state and the second friction element is in the released state. A coast stop control unit, and a friction element control unit that controls a fastening state of the first friction element and the second friction element. The friction element control unit stops the driving force source by the coast stop control unit. When the rotation of the hydraulic power source stops after the command is output, and when the first friction element is in the engaged state and the automatic transmission is in the power transmission state, the second friction element Start supplying hydraulic pressure.

According to another embodiment of the present invention, the driving force source that drives the vehicle, the hydraulic source that is driven by the driving force source to generate hydraulic pressure, and the engagement state of the first friction element and the second friction element An automatic transmission for a vehicle, the transmission ratio of which is changed by the automatic transmission that transmits the driving force of the driving force source to the driving wheels, and a control unit that controls the operation of the driving force source, the hydraulic source, and the transmission mechanism. Applied to the control method. When the vehicle is in a running state, the first friction element is in the engaged state and the second friction element is in the released state, the driving force source stop command is output, and the driving force source stop command is issued. Until the rotation of the hydraulic source stops, and when the first friction element is in the engaged state and the automatic transmission is in the power transmission state, the second friction element is supplied with hydraulic pressure. Start .

  According to the above aspect, after the stop of the driving force source is commanded until the driving of the driving force source stops, that is, while the driving force source is still rotated by the inertial force and the hydraulic pressure is supplied by the hydraulic source. The hydraulic pressure is supplied to the second friction element. Since the hydraulic pressure source can secure the hydraulic pressure necessary for the second friction element and supply the hydraulic pressure to the first friction element in the engaged state, the occurrence of slip of the first friction element in the engaged state can be suppressed, and slipping can be prevented. The uncomfortable feeling given to the driver can be reduced by restraining the fastening shock accompanying the torque loss and the re-fastening of the slipped friction element from changing the longitudinal acceleration of the vehicle.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a continuously variable transmission according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing an example of the configuration of the transmission controller according to the embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating an example of a shift map according to the embodiment of this invention. FIG. 4 is an explanatory diagram for coast stop control of a comparative example. FIG. 5 is an explanatory diagram for coast stop control according to the embodiment of the present invention. FIG. 6 is a flowchart of the coast stop control according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a vehicle equipped with a continuously variable transmission according to an embodiment of the present invention. The vehicle includes an engine 1 as a power source. The output rotation of the engine 1 is via a torque converter 2 with a lock-up clutch, a first gear train 3, a continuously variable transmission (hereinafter simply referred to as "transmission 4"), a second gear train 5, and a final reduction gear 6. Is transmitted to the drive wheel 7. The second gear train 5 is provided with a parking mechanism 8 that mechanically locks the output shaft of the transmission 4 at the time of parking.

  The vehicle is provided with a mechanical oil pump 10m that receives rotation of the engine 1 and is driven by using a part of the power of the engine 1, and an electric oil pump 10e that is driven by receiving power supply from the battery 13. It has been. The transmission 4 controls the hydraulic control circuit 11 that regulates the hydraulic pressure supplied from at least one of the mechanical oil pump 10 m and the electric oil pump 10 e and supplies the hydraulic pressure to each part of the transmission 4, the hydraulic control circuit 11, and the engine 1. And a controller 12 is provided.

  The transmission 4 includes a continuously variable transmission mechanism (hereinafter referred to as “variator 20”) and an auxiliary transmission mechanism 30 provided in series with the variator 20. “To be provided in series” means that the variator 20 and the auxiliary transmission mechanism 30 are provided in series in the same power transmission path. The auxiliary transmission mechanism 30 may be directly connected to the output shaft of the variator 20 as in this example, or may be connected via another transmission or power transmission mechanism (for example, a gear train).

  The variator 20 is a belt-type continuously variable transmission mechanism that includes a primary pulley 21, a secondary pulley 22, and a belt (V belt) 23 that is wound around the pulleys 21 and 22. Each of the pulleys 21 and 22 includes a fixed conical plate, a movable conical plate that is arranged with a sheave surface facing the fixed conical plate, and forms a V-groove between the fixed conical plate, and a rear surface of the movable conical plate. And hydraulic cylinders 23a and 23b for displacing the movable conical plate in the axial direction. When the hydraulic pressure supplied to the hydraulic cylinders 23a and 23b is adjusted, the width of the V groove changes, the contact radius between the belt 23 and each pulley 21 and 22 changes, and the speed ratio vRatio of the variator 20 changes steplessly. .

  The subtransmission mechanism 30 is a transmission mechanism having two forward speeds and one reverse speed. The sub-transmission mechanism 30 is connected to a Ravigneaux type planetary gear mechanism 31 in which two planetary gear carriers are connected, and a plurality of friction elements connected to a plurality of rotating elements constituting the Ravigneaux type planetary gear mechanism 31 to change their linkage state. Elements (Low brake 32, High clutch 33, Rev brake 34). When the hydraulic pressure supplied to each of the friction elements 32 to 34 is adjusted and the engagement / release state of each of the friction elements 32 to 34 is changed, the gear position of the auxiliary transmission mechanism 30 is changed.

  For example, if the Low brake 32 is engaged and the High clutch 33 and the Rev brake 34 are released, the gear position of the subtransmission mechanism 30 is the first speed. If the high clutch 33 is engaged and the low brake 32 and the rev brake 34 are released, the speed stage of the subtransmission mechanism 30 becomes the second speed having a smaller speed ratio than the first speed. When the Rev brake 34 is engaged and the Low brake 32 and the High clutch 33 are released, the gear position of the subtransmission mechanism 30 is reverse. In the following description, the transmission 4 is expressed as “the transmission 4 is in the low speed mode” when the shift stage is the first speed, and “the transmission 4 is in the high speed mode” when the speed is the second speed. .

  The controller 12 is a control means for comprehensively controlling the engine 1 and the transmission 4, and as shown in FIG. 2, a CPU 121, a storage device 122 including a RAM / ROM, an input interface 123, an output interface 124, , And a bus 125 for interconnecting them.

  The input interface 123 includes an output signal of an accelerator opening sensor 41 for detecting an accelerator pedal opening (hereinafter referred to as “accelerator opening APO”), an input rotational speed of the transmission 4 (= the rotational speed of the primary pulley 21). , Hereinafter referred to as “primary rotational speed Npri”), an output signal from the rotational speed sensor 42, an output signal from the vehicle speed sensor 43 that detects the traveling speed of the vehicle (hereinafter referred to as “vehicle speed VSP”), and the transmission 4. The output signal of the oil temperature sensor 44 for detecting the oil temperature of the engine, the output signal of the inhibitor switch 46 for detecting the position of the select lever 45, the output signal of the brake sensor 47 for detecting the brake pedal depression amount and the brake hydraulic pressure, etc. Entered.

  The storage device 122 stores a control program for the engine 1, a shift control program for the transmission 4, and a shift map (FIG. 3) used in the shift control program. The CPU 121 reads and executes a shift control program stored in the storage device 122, performs various arithmetic processes on various signals input via the input interface 123, and outputs a fuel injection signal, an ignition timing signal, a throttle An opening signal and a shift control signal are generated, and the generated shift control signal is output to the hydraulic control circuit 11 via the output interface 124. Various values used in the arithmetic processing by the CPU 121 and the arithmetic results are appropriately stored in the storage device 122.

  The hydraulic control circuit 11 includes a plurality of flow paths and a plurality of hydraulic control valves. The hydraulic control circuit 11 controls a plurality of hydraulic control valves on the basis of the shift control signal from the controller 12 to switch the hydraulic pressure supply path, and obtains the necessary hydraulic pressure from the hydraulic pressure generated by the mechanical oil pump 10m or the electric oil pump 10e. It is prepared and supplied to each part of the transmission 4. As a result, the gear ratio vRatio of the variator 20 and the gear position of the auxiliary transmission mechanism 30 are changed, and the transmission 4 is changed.

  FIG. 3 shows an example of the shift map stored in the storage device 122 of the controller 12 of the present embodiment.

  On the shift map, the operating point of the transmission 4 is determined based on the vehicle speed VSP and the primary rotational speed Npri. The slope of the line connecting the operating point of the transmission 4 and the zero point of the lower left corner of the transmission map is the overall transmission ratio obtained by multiplying the transmission ratio of the transmission 4 (the transmission ratio vRatio of the variator 20 by the transmission ratio subRatio of the subtransmission mechanism 30). , Hereinafter referred to as “through transmission ratio Ratio”).

  In the shift map, a shift line is set for each accelerator opening APO, and the shift of the transmission 4 is performed according to the shift line selected according to the accelerator opening APO. For simplicity, FIG. 3 shows a full load line (shift line when accelerator opening APO = 8/8), partial line (shift line when accelerator opening APO = 4/8), coast line (accelerator opening). Only the shift line when the degree APO = 0 is shown.

  When the transmission 4 is in the low speed mode, the transmission 4 has a low speed mode lowest line obtained by maximizing the transmission ratio vRatio of the variator 20, and a low speed mode highest line obtained by minimizing the transmission ratio vRatio of the variator 20. You can shift between them. At this time, the operating point of the transmission 4 moves in the A region and the B region.

  On the other hand, when the transmission 4 is in the high speed mode, the transmission 4 has the maximum low speed line obtained by maximizing the transmission ratio vRatio of the variator 20 and the maximum high speed mode obtained by minimizing the transmission ratio vRatio of the variator 20. You can shift between the lines. At this time, the operating point of the transmission 4 moves in the B region and the C region.

  The controller 12 refers to the shift map, sets a through speed ratio Ratio corresponding to the vehicle speed VSP and the accelerator opening APO (vehicle operating state), and controls the speed ratio of the variator 20 and the subtransmission mechanism 30.

  In order to suppress fuel consumption, the controller 12 according to the present embodiment stops the rotation of the engine 1 while the vehicle is running, in addition to the idle stop control that stops the rotation of the engine 1 while the vehicle is stopped. Perform coast stop control.

  The coast stop control is a control that suppresses fuel consumption by automatically stopping the engine 1 while the vehicle is traveling in a low vehicle speed range. The coast stop control is common to the fuel cut control executed when the accelerator is off and the fuel supply to the engine 1 is stopped. However, the normal fuel cut control is executed at a relatively high speed and the engine brake is applied. The lock-up clutch of the torque converter 2 is engaged in order to ensure that the coast stop control is performed at a relatively low speed immediately before the vehicle stops, and the engine 1 is rotated with the lock-up clutch released. It is different in that it is stopped.

In executing the coast stop control, the controller 12 first determines, for example, the following conditions (a) to (f).
(A): The foot is released from the accelerator pedal (accelerator opening APO = 0)
(B): The brake pedal is depressed (the brake sensor 47 is ON)
(C): Vehicle speed is a predetermined low vehicle speed (for example, 15 km / h) or less (d): Lock-up clutch is released (e): High clutch 33 is engaged (f): Low brake 32 is engaged In other words, these conditions are conditions for determining that the driver intends to stop.

  The controller 12 determines that the coast stop condition is satisfied when the conditions (a) to (f) are satisfied. When the coast stop condition is satisfied, the supply of fuel to the engine 1 is stopped and the rotation of the engine 1 is stopped.

  Next, coast stop control of the vehicle configured as described above will be described.

  FIG. 4 is an explanatory diagram at the time of coast stop control of a comparative example in the embodiment of the present invention, and shows a problem of the prior art.

  4 shows, from the top, the output shaft rotational speed No of the transmission 4, the engine rotational speed Ne, the line pressure PL, the command pressure (solid line) and actual pressure (dotted line) of the low brake 32, and the command pressure (solid line) of the high clutch 33. ), Actual pressure (dotted line), and vehicle acceleration. The primary oil pressure Ppri is a value that exemplifies the oil pressure that is regulated by the oil pressure control circuit 11 and is supplied to each part of the transmission 4. The vehicle speed VSP is obtained by multiplying the output rotation speed No by the reduction ratio of the final reduction gear, the wheel diameter of the drive wheels 7, and the like. In FIG. 4, the indicated pressure and the actual pressure of the high clutch 33 are described with a slight difference, but this is merely a mismatch for the sake of explanation. Match.

  FIG. 4 shows an operation when the coast stop condition is satisfied at timing t01 and the engine 1 is stopped in a state where the vehicle is gradually decelerating.

  FIG. 4 shows a state where the driving state of the vehicle transitions from the C region to the B region as the vehicle speed VSP decelerates along the coast line shown in FIG. Therefore, the subtransmission mechanism 30 is in the high speed mode, and among the friction elements, the low brake 32 is controlled to be in the released state, and the high clutch 33 is controlled to be in the engaged state.

  When the engine is stopped by coast stop control, the high clutch 33 is engaged in the auxiliary transmission mechanism 30 to prevent a time lag for engaging the friction element when a reacceleration request such as depression of an accelerator pedal is made. As a power transmission state.

  After the vehicle stops due to the coast stop, in preparation for re-starting, the auxiliary transmission mechanism 30 is shifted to the low speed mode, that is, the high clutch 33 is released and the low brake 32 is controlled to the engaged state.

  At this time, in order to improve the responsiveness, a so-called precharge is performed in which a predetermined hydraulic pressure is supplied to the Low brake 32 that is a friction element in a coasted stop state and a release state before the vehicle stops to prepare for engagement. Start. Details will be described below.

  As described above, when the coast stop condition is satisfied, the controller 12 stops the fuel supply to the engine 1, releases the lock-up clutch of the torque converter, and stops the rotation of the engine 1 (timing t01). ).

  When the supply of fuel to the engine 1 is stopped and the lockup clutch is released, the rotational speed of the engine 1 gradually decreases. Along with this, the rotation of the mechanical oil pump 10m that generates hydraulic pressure by the driving force of the engine 1 also gradually decreases. Thereafter, when the rotation of the engine 1 is completely stopped (timing t02), the rotation of the mechanical oil pump 10m is also stopped and the primary pressure is reduced.

  Even when the engine 1 is stopped, hydraulic pressure is required for the belt clamping force by the pulleys of the variator 20 and the engagement of the friction elements of the auxiliary transmission mechanism 30. For this purpose, the controller 12 starts driving the electric oil pump 10e when coast stop control of the engine 1 is started. Thereby, even if the driving of the mechanical oil pump 10m is stopped and no hydraulic pressure is supplied, the hydraulic pressure of the electric oil pump 10e can be supplied to the hydraulic pressure control circuit 11.

  The hydraulic oil pressure that can be discharged by the electric oil pump 10e is smaller than that of the mechanical oil pump 10m. This is because the transmission 4 does not need to transmit a large torque when the engine 1 is stopped, and the variator 20 or the auxiliary transmission mechanism. This is because it is only necessary to secure the minimum hydraulic pressure necessary for fastening 30. By reducing the capacity of the electric oil pump 10e, the size and weight of the electric oil pump 10e can be reduced.

  Thus, the hydraulic pressure supplied becomes small in the coast stop state.

  Here, the controller 12 determines to shift the auxiliary transmission mechanism 30 from the high speed mode to the constant speed mode. That is, since the vehicle is surely stopped, the auxiliary transmission mechanism 30 is shifted from the high speed mode to the low speed mode to prepare for a subsequent restart. Specifically, the Low brake 32 is set to the engaged state, and the High clutch 33 is set to the released state.

  At this time, prior to controlling the released low brake 32 to the engaged state, precharge for instructing a hydraulic pressure in which the command hydraulic pressure is higher than a predetermined standby hydraulic pressure is started. The precharge control is executed as preparation for controlling the friction element in the released state to the engaged state. A predetermined hydraulic pressure is supplied to the friction element for a predetermined time (or a predetermined amount), and the distance between the friction facings is reduced by compression of the return spring of the friction element in the released state. In other words, precharging is to supply hydraulic pressure to the friction element so as to reduce the interval between the plurality of friction plates provided in the friction element so that the power is transmitted to the friction element. After the precharge is completed, the friction element is controlled to a standby pressure that is in a ready state for fastening. The standby pressure is prepared so that the friction element can immediately transmit torque when the hydraulic pressure is further increased from the same pressure.

  Here, when the precharge is started when the primary oil pressure is reduced in the coast stop state, there may be a problem that the oil pressure supplied to the other friction elements is reduced by the precharge control as follows.

  In FIG. 4, the controller 12 starts precharging the Low brake 32 at timing t03. At this time, the transmission 4 is covered only with the hydraulic pressure discharged from the electric oil pump 10e, and the hydraulic pressure at this time is smaller than the hydraulic pressure supplied by the mechanical oil pump 10m.

  Therefore, when the hydraulic pressure is used due to the start of precharging, the hydraulic pressure decreases transiently, and the hydraulic pressure supplied to the other friction elements to which the hydraulic pressure is supplied, in this case, the engaged high clutch 33 is also transient. Decline.

  At this time, since the vehicle is still running, there is a possibility that the High clutch 33 that is a friction element transmitting torque temporarily slips. When the friction element slips and re-engages due to this temporary slip, the torque loss accompanying the slip and the fastening shock accompanying the re-engagement of the slipped friction element will change the longitudinal acceleration of the vehicle, giving the driver a sense of incongruity There is a case.

  In other words, this is caused by starting precharge in a state where the hydraulic pressure supplied to the transmission 4 is reduced by the coast stop control.

  Therefore, in the embodiment of the present invention, the friction element does not generate a slip during the coast stop control by configuring as follows.

  FIG. 5 is an explanatory diagram for coast stop control according to the embodiment of the present invention.

  FIG. 5 shows, from the top, the output shaft rotational speed No of the transmission 4, the engine rotational speed Ne, the line pressure PL, the command pressure (solid line) and actual pressure (dotted line) of the low brake 32, and the command pressure (solid line) of the high clutch 33. ), Actual pressure (dotted line), and vehicle acceleration. The primary oil pressure Ppri is a value that exemplifies the oil pressure that is regulated by the oil pressure control circuit 11 and is supplied to each part of the transmission 4. The vehicle speed VSP is obtained by multiplying the output rotation speed No by the reduction ratio of the final reduction gear, the wheel diameter of the drive wheels 7, and the like. In FIG. 5, the indicated pressure and the actual pressure of the high clutch 33 are described with a slight difference, but this is merely a mismatch for the sake of explanation. Match.

  FIG. 5 shows the operation when the coast stop condition is satisfied at the timing t11 and the engine 1 is stopped in a state where the vehicle is gradually decelerating, as in FIG.

  FIG. 5 shows a state where the driving state of the vehicle transitions from the C region to the B region as the vehicle speed VSP decelerates along the coast line shown in FIG. Therefore, the subtransmission mechanism 30 is in the high speed mode, and among the friction elements, the low brake 32 is controlled to be in the released state, and the high clutch 33 is controlled to be in the engaged state.

  When the coast stop condition is satisfied at the timing t11, the controller 12 stops the fuel supply to the engine 1 to stop the rotation of the engine 1 and simultaneously releases the lock-up clutch of the torque converter.

  Here, the controller 12 starts precharging the low brake 32 that is the engagement-side friction element as a preparation stage for shifting the auxiliary transmission mechanism 30 from the high speed mode to the low speed mode.

  That is, immediately after the coast stop control is started (timing t11) until the rotation of the engine 1 is stopped (timing t12), the mechanical oil pump 10m is driven by the rotation of the engine 1 to supply hydraulic pressure. While the mechanical oil pump 10m is driven and the hydraulic pressure is supplied, precharging of the engaging low brake 32 is started.

  The controller 12 starts driving the electric oil pump 10e when coast stop control of the engine 1 is started. Thereafter, the rotation of the engine 1 is completely stopped (timing t12), and thereafter, hydraulic pressure is supplied by the electric oil pump 10e.

  The low brake 32 and the high clutch 33 are maintained in the standby state and the engaged state by the hydraulic pressure supplied by the electric oil pump 10e, respectively. In particular, the low brake 32 on the engagement side waits at the standby pressure after the precharge is started and the precharge is completed. The standby pressure is a hydraulic pressure before the Low brake 32 starts to have a torque transmission capacity when the hydraulic pressure is further increased. This hydraulic pressure is supplied by the electric oil pump 10e.

  Such control prevents slip-re-engagement of the friction element during coast stop control, and torque loss and slip friction caused by the slip that occurs when the friction element performs slip-re-engagement. It is possible to reduce the uncomfortable feeling to the driver due to the fastening shock accompanying the re-fastening of the elements.

  In the embodiment of the present invention, the controller 12 starts precharging the low brake 32 that is the engagement-side friction element after the controller 12 outputs a coast stop command to the engine 1 and before the rotation of the engine 1 stops. It is a feature.

  With this feature, the mechanical oil pump 10m is driven by the rotation of the engine 1 and precharging is started while the hydraulic pressure by the mechanical oil pump 10m is secured (higher hydraulic pressure than that supplied by the electric oil pump 10e). it can. Thereby, it is possible to prevent the torque transmission capacity of the engaged friction element (high clutch 33) and the belt clamping force of the variator 20 from being reduced.

  In the embodiment of the present invention, the controller 12 is controlled to start precharging after the controller 12 outputs the coast stop command until the rotation of the engine 1 stops. Here, as another method, it is conceivable to start the precharge before outputting the coast stop command, that is, before the timing t11 in FIG. That is, in a state where the engine 1 is rotating and the mechanical oil pump 10m is driven, precharging of the Low brake 32 that is a friction element on the engagement side is started.

  However, before the timing t11, the engine 1 is driven, the lock-up clutch is engaged, and the high clutch 33 is engaged. In other words, there are a plurality of targets for transmitting the torque by supplying the hydraulic pressure. The variator 20 also transmits torque by the belt clamping force.

  Further, in such a state, that is, in a state where the vehicle speed VSP is reduced and the engine rotational speed Ne is low, torque transmission of the lockup clutch is performed for the purpose of preventing engine 1 from being input by torque from the driving wheel side such as sudden braking. The capacity is set to the minimum capacity that can maintain torque transmission.

  That is, in a state immediately before the coast stop is permitted, even if the mechanical oil pump 10m is driven by the engine 1, there are a plurality of hydraulic pressure supply targets, so there is little margin for the hydraulic pressure. In particular, the lock-up clutch has a torque transmission capacity. Is set low.

  At this time, as described above, when the precharge of the low brake 32 that is the engagement side friction element is started, the hydraulic pressure in the transmission 4 becomes insufficient due to the hydraulic pressure used for the precharge control. As a result, a slip of the lockup clutch and a slip of the high clutch 33 in the engaged state may occur, and the driver may feel uncomfortable as described above with reference to FIG.

  In the embodiment of the present invention, as described above, the controller 12 outputs the coast stop command to the engine 1 until the rotation of the engine 1 stops, that is, the engine 1 is still rotated by the inertial force. Precharging is started in a state where the oil pump 10m is driven. Thereby, the supplied hydraulic pressure can be sufficiently secured, and the occurrence of slip of the high clutch 33 that is the friction element in the engaged state can be suppressed.

  In the embodiment of the present invention, the precharge is started in a state where the mechanical oil pump 10m is driven, but the precharge is not necessarily completed in the state where the mechanical oil pump 10m is driven. That is, it is not always necessary to secure the hydraulic pressure necessary for the precharge control for the necessary time (or amount). A large hydraulic pressure is required for the precharge control. When the hydraulic pressure is insufficient due to the coast stop control, if the precharge control can be assisted by the mechanical oil pump 10m, only the electric oil pump 10e is used. Even when the oil pressure becomes the oil pressure, a decrease in the oil pressure can be suppressed.

  FIG. 6 is a flowchart of coast stop control executed by the controller 12 according to the embodiment of the present invention.

  The flowchart shown in FIG. 6 is executed by the controller 12 at a predetermined cycle (for example, every 10 ms).

  First, in step S10, the controller 12 acquires the state of the vehicle from various sensors, switches, and the like. Specifically, signals such as a vehicle speed VSP, a brake signal BRK, and an accelerator opening APO are acquired. The engagement state of the friction elements (Low brake 32, High clutch 33, Rev brake 34) of the auxiliary transmission mechanism 30 is acquired.

  Next, in step S20, the controller 12 determines whether or not a coast stop condition is satisfied. Specifically, it is determined that the coast stop condition is satisfied when the above-described conditions (a) to (f) are satisfied. In the present embodiment, regarding the conditions (e) and (f), it is assumed that the coast stop condition is satisfied when the high clutch 33 is in the engaged state and the low brake 32 is in the released state. If it is determined that the coast stop condition is satisfied, the process proceeds to step S30. If it is determined that the coast stop condition is not satisfied, the process proceeds to step S100.

  In step S30, the controller 12 determines whether or not the flag F is established (whether or not F is 1). The flag F is a flag that is satisfied when the coast stop control is actually started after the coast stop condition is satisfied. If the flag F has already been established, the process proceeds to step S60 without performing the processes of steps S40 and S50. If the flag F is not established, the process proceeds to step S40.

  In step S40, the controller 12 outputs a coast stop command to stop the engine 1, and outputs a signal for driving the electric oil pump 10e to drive the electric oil pump 10e. At the same time, a lockup clutch release command is also output. After step S40, the controller 12 proceeds to step S50 and sets the flag F. After step S50, the process proceeds to step S60.

  In step S60, it is determined whether or not a sudden deceleration of the vehicle has been detected. For example, the controller 12 detects sudden deceleration based on a brake signal BRK from the brake sensor 47, a change in vehicle acceleration, or the like. When the vehicle decelerates rapidly, it is necessary to return the variator 20 low. At this time, if the precharge is started, the oil pressure is taken for the precharge control, and the low return of the variator 20 may be incomplete. When sudden deceleration of the vehicle is compared with the first time required to stop and the second time required to shift from the current gear ratio to the gear ratio corresponding to the lowest or the lowest, This is a deceleration state in which the first time is shorter than the second time.

  Therefore, when the sudden deceleration of the vehicle is detected, the process proceeds to step S90, and the controller 12 stops the precharge being executed. That is, the supply of hydraulic pressure to the low brake 32 is stopped. After the process of step S90, the process by this flowchart is once complete | finished and it returns to another process.

  When the rapid deceleration of the vehicle is not detected, the process proceeds to step S70, and it is determined whether or not the engine rotation speed Ne has become zero, that is, whether or not the rotation of the engine 1 has stopped.

  When the engine rotation speed Ne becomes zero, the rotation of the mechanical oil pump 10m stops, and the hydraulic oil supply source is only the electric oil pump 10e. Also in this case, the lowered hydraulic pressure is taken by the precharge control, and there is a possibility that the same uncomfortable feeling as in the prior art described in FIG. 4 is given. Therefore, when the engine rotation speed Ne becomes zero, the process proceeds to step S90, and the controller 12 stops the precharge being executed.

  If it is determined that the engine rotation speed Ne is not zero, the process proceeds to step S80, and the controller 12 starts or maintains precharge of the engagement-side friction element (here, the low brake 32). After the process of step S80, the process by this flowchart is once complete | finished and it returns to another process.

  If it is determined in step S20 that the coast stop condition is not satisfied, the process proceeds to step S100, and if the coast stop control has already been executed, the controller 12 terminates the coast stop control. Stops the output of the stop command. As a result, the engine 1 restarts and the coast stop ends. In order to prevent hunting at the start and end of the coast stop, a hysteresis may be provided in the condition of the coast stop end.

  After step S100, the controller 12 sets the flag F to non-established in step S110, temporarily ends the processing according to this flowchart, and returns to other processing.

  By such control, when coast stop control is executed, precharge can be started prior to engagement of the engagement-side friction element (for example, the Low brake 32).

  As described above, the embodiment of the present invention includes the engine 1 as a driving force source that drives a vehicle, the mechanical oil pump 10m as a hydraulic source that is driven by the driving force source and generates hydraulic pressure, A transmission 4 having a sub-transmission mechanism 30 that changes the gear ratio according to the engagement state of the friction element (High clutch 33) and the second friction element (Low brake 32) and transmits the driving force of the driving force source to the driving wheels. And a controller 12 that controls the operation of the engine 1, the mechanical oil pump 10 m and the transmission 4.

  The controller 12 is configured as a coast stop control unit that performs a coast stop that stops the engine in a running state of the vehicle.

  The controller 12 is configured as a friction element control unit that controls the low brake to the engaged state when the high clutch 33 is engaged and the low brake 32 is released during the coast stop.

  The controller 12 starts precharging to supply hydraulic pressure in order to set the Low brake 32 in a ready state for fastening until the driving of the engine 1 stops after the stop of the engine 1 is commanded.

  In the embodiment of the present invention, from when the stop of the engine 1 is commanded until the drive of the engine 1 stops, that is, in a state where the engine 1 is still rotated by the inertial force and the mechanical oil pump 10m is driven, Precharging of the low brake 32 as the second friction element is started. Thereby, even if the hydraulic pressure is taken by the start of precharging, sufficient hydraulic pressure is supplied by the mechanical oil pump 10m having a relatively large discharge pressure. The high clutch 33, which is the first friction element, is in the engaged state and transmitting torque, and the occurrence of slipping of the first friction element is suppressed. Therefore, it is possible to suppress the uncomfortable feeling given to the driver by suppressing the torque loss accompanying the slip of the friction element and the fastening shock accompanying the re-engagement of the slipped friction element from changing the longitudinal acceleration of the vehicle. When the rotation of the drive source is stopped, that is, the rotation of the engine 1 is stopped, the rotation of the mechanical oil pump 10m that is the hydraulic source is stopped, and the discharge pressure of the hydraulic source becomes zero. Therefore, in the embodiment of the present invention, “rotation stop of the hydraulic pressure source” is determined by “rotation stop of the engine 1”.

  When the stop of the engine 1 is instructed (substantially simultaneously), the controller 12 starts precharging. Thus, the precharge is started in a state where the rotation of the engine 1 is still sufficiently large and the hydraulic pressure generated by the mechanical oil pump 10m is sufficiently high, so that the hydraulic pressure generated by the mechanical oil pump 10m (the engine rotational speed Ne is zero). The precharge can be completed, and the decrease in hydraulic pressure is suppressed, and the occurrence of slipping of the high clutch 33, which is the first friction element, is suppressed. Therefore, it is possible to suppress the uncomfortable feeling given to the driver by suppressing the torque loss accompanying the slip of the friction element and the fastening shock accompanying the re-engagement of the slipped friction element from changing the longitudinal acceleration of the vehicle.

  The sub-transmission mechanism 30 of the transmission 4 has a high-speed mode that is a first state in which the high clutch 33 is engaged and a low-speed mode that is a second state in which the low brake 32 is engaged. The transmission gear ratio is set to a lower side than the high speed mode.

  That is, when coast stop control is performed in the high speed mode in which the high clutch 33 is in the second state in the engaged state, the low brake 32 is controlled in the engaged state to change to the low speed mode in the second state. Thus, the vehicle can be re-accelerated and re-started at a lower gear ratio, and the driving force can be secured.

  The transmission 4 is provided with a torque converter 2 having a lock-up clutch, and when performing a coast stop, the engine 1 is stopped and the lock-up clutch is released. With such a configuration, the lockup clutch or the high clutch 33 does not slip, so the vehicle speed range in which the engine 1 is stopped can be expanded to the vehicle speed at which the lockup clutch is released. The stop area can be expanded and fuel consumption can be improved.

  The transmission 4 includes a variator 20 that is a continuously variable transmission mechanism that can change a gear ratio by changing a winding diameter of a power transmission belt held by hydraulic pressure supplied to a pulley. The controller 12 starts precharging between the start of coast stop control and the stop of the engine 1 as described above, but stops precharging when it detects that the vehicle is decelerating rapidly. Is configured to do.

  When the vehicle suddenly decelerates, it is necessary to control the through speed ratio of the transmission 4 to the Low side in preparation for re-starting after stopping. At this time, in the auxiliary transmission mechanism 30, the engagement and release of the friction element can be performed when the vehicle is stopped, but the change of the transmission ratio of the variator 20 needs to be in a rotating state. For this reason, when the vehicle is suddenly decelerated, the precharge is stopped and the hydraulic pressure is used only to return the gear ratio of the variator to the low side, thereby making it possible to ensure restart after sudden stop.

  The transmission 4 has a mechanical oil pump 10m as a first hydraulic source driven by the engine 1 as a hydraulic source, and electric oil as a second hydraulic source capable of supplying hydraulic pressure regardless of the driving state of the engine 1. It has a pump 10e. The controller 12 is configured to command the drive of the electric oil pump 10e during the coast stop control. Thereby, the hydraulic pressure can be supplied to the transmission 4 even when the engine 1 is stopped, and the friction element can be maintained in the fastening preparation state. Furthermore, the belt clamping force of the variator 20 can also be ensured.

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  For example, in the above embodiment, a belt type continuously variable transmission mechanism is provided as the variator 20, but the variator 20 is a continuously variable transmission mechanism in which a chain is wound around pulleys 21 and 22 instead of the belt 23. May be. Alternatively, the variator 20 may be a toroidal continuously variable transmission mechanism in which a tiltable power roller is disposed between the input disk and the output disk.

  In the above embodiment, the engine 1 that is an internal combustion engine has been described as an example of the driving force source. However, the present invention is not limited to this, and a motor or another driving force source may be used.

  In the above embodiment, the sub-transmission mechanism 30 is a transmission mechanism having two stages of first speed and second speed as the forward shift stage. However, the sub-transmission mechanism 30 is a forward shift stage and has three or more shift stages. A transmission mechanism having the same may be used. In this case, although another friction element may be present, the friction element for realizing a lower gear ratio in preparation for re-start during coast stop control is the same as the low brake 32 described above. Can be performed.

  The auxiliary transmission mechanism 30 is configured using a Ravigneaux type planetary gear mechanism, but is not limited to such a configuration. For example, the auxiliary transmission mechanism 30 may be configured by combining a normal planetary gear mechanism and a friction element, or a plurality of power transmission paths configured by a plurality of gear trains having different gear ratios, and these power transmissions. You may comprise by the friction element which switches a path | route.

  In the embodiment of the present invention, the precharge execution area is from the start of the coast stop control to the stop of the rotation of the engine 1, but the end timing of the precharge execution area is not necessarily the stop of the engine 1 rotation. Not necessarily. For example, the engine speed Ne> a predetermined threshold value (a threshold value that can ensure the discharge pressure) may be set, or a line pressure PL> a predetermined threshold value (a threshold value that can ensure the discharge pressure) may be set. The passage of a predetermined time from the start of coast stop control may be greater than a predetermined threshold (a threshold at which the discharge pressure can be reliably ensured).

  The best mode of precharge control start timing is start of coast stop control, but is not limited to this, and precharge control may be started with a delay from the start point of coast stop control. This delay (precharge control start timing) is, for example, as follows: engine speed Ne ≦ predetermined threshold (threshold for ensuring discharge pressure), line pressure PL> predetermined threshold (threshold for ensuring discharge pressure) Also good. The determination may be made based on the passage of a predetermined time from the start of coast stop control> a predetermined threshold value (a threshold value at which the discharge pressure can be reliably ensured).

This application claims the priority based on Japanese Patent Application No. 2012-167320 for which it applied to the Japan Patent Office on July 27, 2012. The entire contents of these applications are incorporated herein by reference.

Claims (8)

A driving force source for driving the vehicle;
A hydraulic pressure source driven by the driving force source to generate hydraulic pressure;
An automatic transmission in which a transmission gear ratio is changed depending on a fastening state of the first friction element and the second friction element, and the driving force of the driving force source is transmitted to driving wheels;
A control unit for controlling operations of the driving force source, the hydraulic pressure source, and the automatic transmission;
A control device for an automatic transmission in a vehicle comprising:
The controller is
A coast stop that outputs a stop command to the driving force source to stop the driving force source when the vehicle is in a traveling state, and the first friction element is in a fastening state and the second friction element is in a released state. A coast stop control unit,
A friction element control unit that controls a fastening state of the first friction element and the second friction element;
The friction element control unit includes a period from when the stop command of the driving force source is output by the coast stop control unit until the rotation of the hydraulic power source stops, and the first friction element is in an engaged state. And the control apparatus of the automatic transmission which starts supply of a hydraulic pressure to the said 2nd friction element, when the said automatic transmission is in a power transmission state . A driving force source for driving the vehicle;
A hydraulic pressure source driven by the driving force source to generate hydraulic pressure;
An automatic transmission in which a transmission gear ratio is changed depending on a fastening state of the first friction element and the second friction element, and the driving force of the driving force source is transmitted to driving wheels;
A control unit for controlling operations of the driving force source, the hydraulic pressure source, and the automatic transmission;
A control device for an automatic transmission in a vehicle comprising:
The controller is
A coast stop that outputs a stop command to the driving force source to stop the driving force source when the vehicle is in a traveling state, and the first friction element is in a fastening state and the second friction element is in a released state. A coast stop control unit,
A friction element control unit that controls a fastening state of the first friction element and the second friction element;
The friction element control unit includes a period from when the stop command of the driving force source is output by the coast stop control unit until the rotation of the hydraulic power source stops, and the first friction element is in an engaged state. The hydraulic pressure is started to be supplied to the second friction element,
The automatic transmission is
A first state in which the first friction element is engaged;
A second state in which the second friction element is engaged;
Have
The control device for an automatic transmission, wherein the second state transmits the driving force of the driving force source to the driving wheels at a lower gear ratio than the first state . A driving force source for driving the vehicle;
A hydraulic pressure source driven by the driving force source to generate hydraulic pressure;
An automatic transmission in which a transmission gear ratio is changed depending on a fastening state of the first friction element and the second friction element, and the driving force of the driving force source is transmitted to driving wheels;
A control unit for controlling operations of the driving force source, the hydraulic pressure source, and the automatic transmission;
A control device for an automatic transmission in a vehicle comprising:
The controller is
A coast stop that outputs a stop command to the driving force source to stop the driving force source when the vehicle is in a traveling state, and the first friction element is in a fastening state and the second friction element is in a released state. A coast stop control unit,
A friction element control unit that controls a fastening state of the first friction element and the second friction element;
The friction element control unit includes a period from when the stop command of the driving force source is output by the coast stop control unit until the rotation of the hydraulic power source stops, and the first friction element is in an engaged state. The hydraulic pressure is started to be supplied to the second friction element,
The automatic transmission includes a torque converter having a lock-up clutch,
The coast stop control unit outputs an instruction to stop the driving force source and releases the lock-up clutch . A driving force source for driving the vehicle;
A hydraulic pressure source driven by the driving force source to generate hydraulic pressure;
An automatic transmission in which a transmission gear ratio is changed depending on a fastening state of the first friction element and the second friction element, and the driving force of the driving force source is transmitted to driving wheels;
A control unit for controlling operations of the driving force source, the hydraulic pressure source, and the automatic transmission;
A control device for an automatic transmission in a vehicle comprising:
The controller is
A coast stop that outputs a stop command to the driving force source to stop the driving force source when the vehicle is in a traveling state, and the first friction element is in a fastening state and the second friction element is in a released state. A coast stop control unit,
A friction element control unit that controls a fastening state of the first friction element and the second friction element;
The friction element control unit includes a period from when the stop command of the driving force source is output by the coast stop control unit until the rotation of the hydraulic power source stops, and the first friction element is in an engaged state. The hydraulic pressure is started to be supplied to the second friction element,
The automatic transmission has a continuously variable transmission mechanism capable of changing a gear ratio by changing a winding diameter of a power transmission belt held by hydraulic pressure supplied to a pulley;
The friction element controller is
The supply of hydraulic pressure to the second friction element is started after the coast stop control unit outputs a stop command of the driving force source until the driving of the driving force source stops,
A control device for an automatic transmission that stops supply of hydraulic pressure to the second friction element when it is detected that the vehicle is suddenly decelerated . A control device for an automatic transmission according to any one of claims 1 to 4,
Starting the supply of hydraulic pressure to the second friction element is a precharge control for supplying hydraulic pressure to the second friction element so that the second friction element is in a state immediately before starting the power transmission. control device of a <br/> automatic transmission. A control device for an automatic transmission according to any one of claims 1 to 5,
The automatic transmission control device , wherein the friction element control unit starts supplying hydraulic pressure to the second friction element when the coast stop control unit outputs a stop command of the driving force source . The control device for an automatic transmission according to any one of claims 1 to 6,
The hydraulic source includes a first hydraulic source driven by the driving force source, and a second hydraulic source capable of supplying hydraulic pressure regardless of the driving state of the driving force source,
The coast stop control unit is a control device for an automatic transmission that commands driving of the second hydraulic pressure source when outputting a stop command of the driving force source. A driving force source for driving the vehicle;
A hydraulic pressure source driven by the driving force source to generate hydraulic pressure;
An automatic transmission in which a transmission gear ratio is changed depending on a fastening state of the first friction element and the second friction element, and the driving force of the driving force source is transmitted to driving wheels;
A control unit that controls operations of the driving force source, the hydraulic pressure source, and the transmission mechanism;
A method for controlling an automatic transmission in a vehicle comprising:
When the vehicle is in a running state, the first friction element is in a fastening state and the second friction element is in a released state, a stop command for the driving force source is output,
The first friction element is in the engaged state and the automatic transmission is in the power transmission state from when the stop of the driving force source is commanded until the rotation of the hydraulic power source stops. A control method for an automatic transmission that starts supplying hydraulic pressure to the second friction element.

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