WO2014017356A1

WO2014017356A1 - Control device and control method for automatic transmission

Info

Publication number: WO2014017356A1
Application number: PCT/JP2013/069413
Authority: WO
Inventors: 若山　英史; 公祐和久; 訓卓青山; 真美子井上; 詔生浅井
Original assignee: ジヤトコ株式会社
Priority date: 2012-07-27
Filing date: 2013-07-17
Publication date: 2014-01-30
Also published as: JP5768188B2; CN104508331A; KR20150036238A; JPWO2014017356A1; KR20160139055A; KR101929107B1; CN104508331B

Abstract

The present invention is equipped with: a coasting-stop control unit that stops the drive power source and performs a coasting stop when a first friction element is engaged and a second friction element is disengaged, when a vehicle is travelling; and a friction element control unit that controls the engagement of the first friction element and the engagement of the second friction element. The friction element control unit begins the supply of hydraulic pressure to the second friction element in the interval between the issuing of the command from the coasting-stop control unit to stop the drive power source and the stopping of the rotation of the hydraulic pressure source.

Description

Control device and control method of automatic transmission

The present invention relates to a control device and control method of an automatic transmission in a vehicle that performs stopping and restarting of a driving power source.

2. Description of the Related Art An idle stop technology is widely used to improve fuel efficiency by stopping an engine that is a driving power source when the vehicle is stopped. In order to further improve the fuel performance, so-called coast stop control, in which the engine is stopped before the vehicle stops, such as at the time of deceleration, as well as when the vehicle is stopped, has been put to 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, switching of the friction element may be performed in preparation for reacceleration and re-start. On the other hand, when the engine is stopped while traveling, the oil pump driven by the engine can not generate the hydraulic pressure, so the supply of the hydraulic pressure for switching the friction element may be reduced.

As control of such an automatic transmission, JP2006-170295A automatically stops the engine while the vehicle is traveling to place the automatic transmission in a neutral state, and after the engine stops, operates the electric oil pump to generate a friction element. It is disclosed to supply hydraulic pressure, that is, to initiate so-called precharging.

In JP2006-170295A, since the automatic transmission is in the neutral state from the start of the coast stop control to the start of the idle stop control, when there is a reacceleration request during the coast stop, the process from the neutral state to the engagement of the friction element A time lag occurs. Therefore, it is also possible to prepare the fastening by supplying a hydraulic pressure having no torque capacity to the friction element in the released state to prepare for the next shift while reducing any occurrence of time lag by setting one of the friction elements in the engaged state. Conceivable.

However, depending on the start timing of supplying hydraulic pressure to the friction element in the release state to prepare for fastening, the friction element in the engagement state may slip, and thus, the torque may be lost due to slip or the engagement may occur. The shock may change the longitudinal acceleration of the vehicle, which may cause the driver to feel uncomfortable.

That is, when the supply of oil pressure to the friction element in the released state is started while the mechanical pump is not driven, the oil pressure supplied to the automatic transmission is reduced and the friction element in the engaged state slips, as described above. There is a possibility that the driver may feel discomfort.

The present invention has been made in view of such problems, and it is an object of the present invention to provide a control device of an automatic transmission capable of suppressing a slip of a friction element and reducing a sense of discomfort given to a driver in coast stop control. I assume.

According to one embodiment of the present invention, a transmission source driving a vehicle, an oil pressure source driven by the driving source to generate an oil pressure, and a transmission gear ratio according to the engagement state of the first friction element and the second friction element And a control unit for transmitting the driving force of the driving force source to the driving wheels, and a control unit for controlling the operation of the driving force source, the hydraulic pressure source, and the transmission mechanism. Applied. The control unit outputs a stop command to the drive power source to stop the drive power source when the vehicle is in a traveling state, the first friction element is in the engaged state, and the second friction element is in the release state. And a friction element control unit for controlling an engagement state of the first friction element and the second friction element, the friction element control unit stopping the driving force source by the coast stop control unit. The second friction element is started to be supplied with hydraulic pressure after the command is issued until the rotation of the hydraulic pressure source is stopped.

Further, according to another embodiment of the present invention, a driving force source for driving a vehicle, an oil pressure source driven by the driving force source to generate an oil pressure, and a fastening state of a first friction element and a second friction element The automatic transmission in a vehicle includes: an automatic transmission that changes the transmission gear ratio and 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 pressure source, and the transmission mechanism. Applied to the control method of The control method is such that when the vehicle is in a traveling state, the first friction element is in the engaged state, and the second friction element is in the release state, the drive power source stop command is output to stop the drive power source. Then, the supply of oil pressure to the second friction element is started while the rotation of the oil pressure source is stopped.

According to the above aspect, during a period from when the driving power source is instructed to stop until when the driving power source stops being driven, that is, while the driving power source is still rotated by inertia force and supplied with oil pressure by the oil pressure source. , Supply hydraulic pressure to the second friction element. Since the hydraulic pressure source can ensure the necessary hydraulic pressure for the second friction element and can 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, It is possible to suppress a sense of incongruity given to the driver by suppressing that the fastening shock accompanying the torque loss and the re-engagement of the slipped friction element becomes the longitudinal acceleration change 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 view showing an example of the configuration of the transmission controller according to the embodiment of the present invention. FIG. 3 is an explanatory view showing an example of a shift map according to the embodiment of the present invention. Drawing 4 is an explanatory view at the time of coast stop control of a comparative example Drawing 5 is an explanatory view at the time of coast stop control of an embodiment of the present invention. FIG. 6 is a flowchart of coast stop control according to the embodiment of this invention.

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

FIG. 1 is a schematic block diagram of a vehicle equipped with a continuously variable transmission according to an embodiment of the present invention. The vehicle is equipped with an engine 1 as a power source. The output rotation of the engine 1 is performed via a torque converter 2 with a lockup 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. And is transmitted to the drive wheel 7. The second gear train 5 is provided with a parking mechanism 8 which mechanically locks the output shaft of the transmission 4 in a non-rotatable manner during parking.

The vehicle is provided with a mechanical oil pump 10m, which receives rotation of the engine 1 and is driven using a portion of the power of the engine 1, and an electric oil pump 10e, which is driven by receiving power supply from the battery 13. It is done. The transmission 4 controls the hydraulic control circuit 11, which controls the hydraulic pressure supplied from at least one of the mechanical oil pump 10m and the electric oil pump 10e, and supplies the hydraulic control circuit 11, the engine 1 and the hydraulic control circuit 11. 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. The "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 including a primary pulley 21, a secondary pulley 22, and a belt (V-belt) 23 wound around the

pulleys

21 and 22. The

pulleys

21 and 22 each have a fixed conical plate, a movable conical plate disposed with the sheave surface facing the fixed conical plate and forming a V-groove between the fixed conical plate, and a back surface of the movable conical plate And

hydraulic cylinders

23a and 23b for axially displacing the movable conical plate. 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 transmission ratio vRatio of the variator 20 changes steplessly. .

The auxiliary transmission mechanism 30 is a transmission mechanism having two forward gears and one reverse gear. The auxiliary transmission mechanism 30 is connected to a Ravigneaux type planetary gear mechanism 31 connecting carriers of two planet gears, and a plurality of rotating elements constituting the Ravigneaux type planetary gear mechanism 31, and a plurality of frictions that change the linkage state thereof. An element (Low brake 32, High clutch 33, Rev brake 34) is provided. By adjusting the oil pressure supplied to each of the friction elements 32 to 34 and changing the engagement / release state of each of the friction elements 32 to 34, the gear position of the auxiliary transmission mechanism 30 is changed.

For example, when the Low brake 32 is engaged and the High clutch 33 and the Rev brake 34 are released, the gear position of the auxiliary transmission mechanism 30 becomes the first gear. If the High clutch 33 is engaged and the Low brake 32 and the Rev brake 34 are released, the gear position of the auxiliary transmission mechanism 30 becomes the second gear whose gear ratio is smaller than the first gear. If the Rev brake 34 is engaged and the Low brake 32 and the High clutch 33 are released, the gear position of the auxiliary transmission mechanism 30 is in reverse. In the following description, when the gear position of the auxiliary transmission mechanism 30 is the first speed, it is expressed as "the transmission 4 is in the low speed mode", and when it is the second speed, it is expressed as "the transmission 4 is in the high speed mode". .

The controller 12 is a control unit that controls the engine 1 and the transmission 4 in an integrated manner, and as shown in FIG. 2, the CPU 121, a storage device 122 composed of a RAM and ROM, an input interface 123, and an output interface 124. , And a bus 125 interconnecting them.

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

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

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

FIG. 3 shows an example of a shift map stored in the storage device 122 of the controller 12 of this 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 shift map is the transmission ratio of the transmission 4 (the overall transmission ratio obtained by multiplying the transmission ratio v Ratio of the variator 20 by the transmission ratio sub Ratio of the auxiliary transmission mechanism 30 Hereinafter, it is referred to as “through gear 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 a shift line selected according to the accelerator opening APO. For simplicity in FIG. 3, all load lines (shift lines when the accelerator opening APO is 8/8), partial lines (shift lines when the accelerator opening APO is 4/8), and a 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 can obtain the low speed mode Lowest line obtained by maximizing the transmission ratio vRatio of the variator 20 and the low speed mode highest line obtained by minimizing the transmission ratio vRatio of the variator 20 It is possible to shift between gears. At this time, the operating point of the transmission 4 moves in the A area and the B area.

On the other hand, when the transmission 4 is in the high speed mode, the transmission 4 can obtain the high speed mode Lowest line obtained by maximizing the transmission ratio v Ratio of the variator 20 and the high speed mode highest obtained by minimizing the transmission ratio v Ratio of the variator 20. You can shift between the lines. At this time, the operating point of the transmission 4 moves in the B area and the C area.

The controller 12 controls the transmission ratio of the variator 20 and the auxiliary transmission mechanism 30 by setting the through transmission ratio Ratio corresponding to the vehicle speed VSP and the accelerator opening APO (the driving state of the vehicle) with reference to the transmission map.

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

The coast stop control is control for automatically stopping the engine 1 to suppress the fuel consumption while the vehicle is traveling in the low vehicle speed region. The coast stop control is common to the fuel cut control performed when the accelerator is off and to stop the fuel supply to the engine 1, but the normal fuel cut control is performed at relatively high speed traveling and the engine brake While the lockup clutch of the torque converter 2 is engaged in order to secure it, the coast stop control is executed at a relatively low speed traveling just before the vehicle stops, and the engine 1 is rotated with the lockup clutch released. It differs in the point to make it stop.

In performing the coast stop control, the controller 12 first determines, for example, the following conditions (a) to (f).
(A): A foot is released from the accelerator pedal (accelerator opening APO = 0)
(B): The brake pedal is depressed (brake sensor 47 is ON)
(C): Vehicle speed is lower than a predetermined low vehicle speed (for example, 15 km / h) (d): Lock-up clutch is released (e): High clutch 33 engaged state (f): Low brake 32 engaged state These conditions are, in other words, conditions for judging 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 view at the time of coast stop control of a comparative example in the embodiment of the present invention, and shows problems of the prior art.

In FIG. 4, from the top, the output shaft rotational speed No of the transmission 4, the engine rotational speed Ne, the line pressure PL, the indicated pressure (solid line) and the actual pressure (dotted line) of the low brake 32, the indicated pressure (solid line) of the high clutch 33 And actual pressure (dotted line) and acceleration of the vehicle. The primary hydraulic pressure Ppri is a value that is adjusted by the hydraulic control circuit 11 and the hydraulic pressure supplied to each part of the transmission 4 is exemplified. A vehicle speed VSP can be obtained by multiplying the output rotational speed No by the reduction ratio of the final reduction gear, the wheel diameter of the drive wheel 7 and the like. In FIG. 4, the command pressure of the High clutch 33 and the actual pressure are described with a slight difference, but this is merely a disagreement for the sake of explanation, and in practice the command pressure and the actual pressure are Match

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

FIG. 4 shows a state where the vehicle speed VSP is decelerated along the cost line shown in FIG. 3 and the transition from the region C to the region B occurs. Therefore, the auxiliary transmission mechanism 30 is in the high speed mode, and among the friction elements, the Low brake 32 is controlled to the released state, and the High clutch 33 is controlled to the engaged state.

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

After the vehicle is stopped due to the coast stop, the auxiliary transmission mechanism 30 is shifted to the low speed mode in preparation for re-start, 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 responsiveness, a so-called precharging is performed, in which a predetermined hydraulic pressure is supplied to the Low brake 32, which is a friction element in the released state in the coast stop state, before the vehicle stops. Start. The details will be described below.

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

When the fuel supply 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 the 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 to clamp the belt by the pulleys of the variator 20 and to fasten the friction elements of the auxiliary transmission mechanism 30. For this reason, when the coast stop control of the engine 1 is started, the controller 12 starts driving of the electric oil pump 10 e. As a result, even if the mechanical oil pump 10m stops driving and the hydraulic pressure is not supplied, the hydraulic pressure of the electric oil pump 10e can be supplied to the hydraulic control circuit 11.

The hydraulic pressure that can be discharged by the electric oil pump 10e is smaller than the mechanical oil pump 10m. This is because the transmission 4 does not have 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, in the coast stop state, the supplied hydraulic pressure becomes smaller.

Here, the controller 12 determines to shift the auxiliary transmission mechanism 30 from the high speed mode to the constant speed mode. In other words, since it is certain that the vehicle will stop, the auxiliary transmission mechanism 30 is shifted from the high speed mode to the low speed mode to prepare for the subsequent restart. Specifically, the Low brake 32 is engaged, and the High clutch 33 is released.

At this time, prior to controlling the low brake 32 in the released state to the engaged state, precharging is started to instruct an oil pressure in which the instructed oil pressure is higher than a predetermined standby oil pressure. Precharge control is performed in 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 predetermined amount) to reduce the distance between the friction facings, such as by compression of the return spring of the friction element in the released state. That is, the precharging is to supply hydraulic pressure to the friction element in order to reduce the distance between the plurality of friction plates provided on the friction element so as to be in a state immediately before power is transmitted to the friction element. After the precharging is completed, the friction element is controlled to the standby pressure which is the preparation for fastening. The standby pressure prepares the friction element to immediately transmit torque when the hydraulic pressure is further raised and supplied from the same pressure.

Here, when precharging is started when the primary oil pressure is reduced in the coast stop state, there may occur a problem that the oil pressure supplied to the other friction elements is reduced by the precharging 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 supplied with only the hydraulic pressure discharged by 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 by the start of precharging, the hydraulic pressure is transiently lowered, and the other hydraulic pressure to which the hydraulic pressure is supplied, in this case, the hydraulic pressure supplied to the high clutch 33 in the engaged state is also transient. Decrease.

At this time, since the vehicle is still traveling, there is a possibility that the high clutch 33, which is a friction element transmitting torque, may slip temporarily. When the friction element performs slip-re-engagement due to this temporary slip, the torque loss due to the slip and the engagement shock accompanying the re-engagement of the slipped friction element cause a change in longitudinal acceleration of the vehicle, giving the driver a sense of discomfort. There is a case.

That is, this is caused by starting the precharging in a state where the hydraulic pressure supplied to the transmission 4 is reduced by the coast stop control.

So, in embodiment of this invention, it comprised so that a friction element might not generate | occur | produce a slip at the time of coast stop control by comprising as follows.

Drawing 5 is an explanatory view at the time of coast stop control of an embodiment of the present invention.

In FIG. 5, the output shaft rotational speed No of the transmission 4, the engine rotational speed Ne, the line pressure PL, the command pressure of the low brake 32 (solid line) and the actual pressure (dotted line), and the command pressure of the high clutch 33 (solid line) And actual pressure (dotted line) and acceleration of the vehicle. The primary hydraulic pressure Ppri is a value that is adjusted by the hydraulic control circuit 11 and the hydraulic pressure supplied to each part of the transmission 4 is exemplified. A vehicle speed VSP can be obtained by multiplying the output rotational speed No by the reduction ratio of the final reduction gear, the wheel diameter of the drive wheel 7 and the like. Although the indicated pressure and the actual pressure of the High clutch 33 are described with a slight difference in FIG. 5, this is merely a disagreement for the sake of explanation, and in fact, the indicated pressure and the actual pressure are Match

Similarly to FIG. 4, FIG. 5 shows an operation in the case where the coast stop condition is satisfied at timing t11 and the engine 1 is stopped in a state where the vehicle is decelerating gradually.

FIG. 5 shows a state where the vehicle speed VSP decelerates along the cost line shown in FIG. 3 and transitions from the C region to the B region, similarly to FIG. Therefore, the auxiliary transmission mechanism 30 is in the high speed mode, and among the friction elements, the Low brake 32 is controlled to the released state, and the High clutch 33 is controlled to the engaged state.

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

Here, the controller 12 starts precharging of the low brake 32, which is a friction element on the fastening side, as a preparatory step of shifting the auxiliary transmission mechanism 30 from the high speed mode to the low speed mode.

That is, from immediately after the start of the coast stop control (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 and the hydraulic pressure is supplied. While the mechanical oil pump 10m is driven to supply hydraulic pressure, precharging of the low brake 32 on the engagement side is started.

When the coast stop control of the engine 1 is started, the controller 12 starts driving of the electric oil pump 10 e. Thereafter, the rotation of the engine 1 is completely stopped (timing t12), and thereafter the 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, respectively, by the hydraulic pressure supplied by the electric oil pump 10 e. In particular, the low brake 32 on the fastening side starts precharging and stands by the standby pressure after the precharging is completed. The standby pressure is a hydraulic pressure before the Low brake 32 starts to have a torque transfer capacity when the hydraulic pressure is further raised. This hydraulic pressure is supplied by the electric oil pump 10e.

Such control prevents the occurrence of slip-re-engagement of the friction element during coast stop control, and the torque loss or slipped friction associated with the slip that occurs when the friction element performs slip-re-engagement It is possible to reduce the discomfort to the driver due to the fastening shock accompanying the re-engagement of the element.

The embodiment of the present invention starts precharging of the low brake 32, which is a friction element on the fastening side, after the controller 12 outputs the coast stop command to the engine 1 until the rotation of the engine 1 is stopped. Is a feature.

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

In the embodiment of the present invention, control is performed so as to start precharging between the time when the controller 12 outputs the coast stop command and the time when the rotation of the engine 1 is stopped. Here, as another method, it is conceivable to start precharging before outputting the coast stop command, that is, before timing t11 in FIG. That is, in a state where the engine 1 rotates and the mechanical oil pump 10m is driven, precharging of the Low brake 32, which is a friction element on the fastening side, is started.

However, before the timing t11, the engine 1 is driven, the lockup clutch is in the engaged state, and the High clutch 33 is in the engaged state. That is, there are a plurality of targets that supply hydraulic pressure and perform torque transmission. The variator 20 also transmits torque by the belt holding force.

Furthermore, in such a state, that is, when the vehicle speed VSP decreases and the engine rotational speed Ne is low, torque transmission from the lockup clutch is performed for the purpose of preventing engine stalling by torque input from the drive wheel side such as sudden braking. The capacity is set to the minimum capacity that can maintain torque transmission.

That is, in the 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, and the margin of the hydraulic pressure is small. Is set low.

At this time, when precharging of the low brake 32, which is a friction element on the fastening side, is started as described above, the hydraulic pressure in the transmission 4 may be 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, which may cause the driver to feel uncomfortable as described above with reference to FIG.

In the embodiment of the present invention, as described above, after the controller 12 outputs the coast stop command to the engine 1, the engine 1 is still rotated by the inertia force until the rotation of the engine 1 is stopped. Precharge is started while the oil pump 10m is in operation. As a result, the supplied hydraulic pressure can be sufficiently secured, and the occurrence of slip of the high clutch 33, which is a frictional 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 does not necessarily have to be completed in a state where the mechanical oil pump 10m is driven. That is, it is not necessary to secure the necessary hydraulic pressure for the pre-charge control for the necessary time (or amount). A large hydraulic pressure is required for the pre-charge control, but if the pre-charge control can be assisted by the mechanical oil pump 10 m as much as possible when the hydraulic pressure is insufficient due to the coast stop control, only the electric oil pump 10 e Even when the hydraulic pressure is reduced, the drop in hydraulic pressure can be suppressed.

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

The flowchart shown in FIG. 6 is executed in 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, each signal such as the vehicle speed VSP, the brake signal BRK, and the accelerator opening APO is 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 a coast stop condition is satisfied. Specifically, when the above conditions (a) to (f) are satisfied, it is determined that the coast stop condition is 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. When it is determined that the coast stop condition is established, the process proceeds to step S30, and when it is determined that the coast stop condition is not established, the process proceeds to step S100.

In step S30, the controller 12 determines whether a flag F is established (whether F is 1). The flag F is a flag that is established when execution of the coast stop control is actually started after the coast stop condition is established. 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 to drive the electric oil pump 10e to drive the electric oil pump 10e. At this time, a release command for the lockup clutch is also output at the same time. After step S40, the controller 12 shifts to step S50 and establishes the flag F. After step S50, the process proceeds to step S60.

In step S60, it is determined whether sudden deceleration of the vehicle has been detected. The controller 12 detects a rapid deceleration, for example, by a brake signal BRK from the brake sensor 47, a change in acceleration of the vehicle, or the like. When the vehicle suddenly decelerates, it is necessary to perform the Low return of the variator 20. At this time, if the precharging is started, the hydraulic pressure is taken for the precharging control, and the Low return of the variator 20 may be incomplete. The sudden deceleration of the vehicle is the case where the first time required to stop the vehicle is compared with 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 decelerating state in which the first time is shorter than the second time.

Therefore, when the rapid deceleration of the vehicle is detected, the process proceeds to step S90, and the controller 12 stops the precharging in progress. That is, the supply of the hydraulic pressure to the low brake 32 is stopped. After the process of step S90, the process of this flowchart is temporarily ended, and the process returns to another process.

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

When the engine rotational speed Ne becomes zero, the mechanical oil pump 10m stops rotating, and the hydraulic pressure supply source is only the electric oil pump 10e. Also in this case, the lowered hydraulic pressure is taken to the pre-charge control, which may give the same sense of incongruity as the prior art described with reference to FIG. Therefore, when the engine rotation speed Ne becomes zero, the process proceeds to step S90, and the controller 12 stops the precharging in progress.

If it is determined that the engine rotational speed Ne is not zero, the process proceeds to step S80, where the controller 12 starts or maintains precharging of the engagement-side friction element (here, the low brake 32). After the process of step S80, the process of this flowchart is temporarily ended, and the process returns to another process.

In step S20, when it is determined that the coast stop condition is not established, the process proceeds to step S100, and when the coast stop control has already been executed, the controller 12 performs the coast stop control to end. Stop output of 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, hysteresis may be provided in the condition of the coast stop end.

After step S100, the controller 12 sets the flag F to not established in step S110, temporarily terminates the process according to this flowchart, and returns to another process.

With such control, when coast stop control is performed, precharging can be started prior to engagement of the engagement-side friction element (e.g., the low brake 32).

As described above, the embodiment of the present invention includes an engine 1 as a driving power source for driving a vehicle, a mechanical oil pump 10m as a hydraulic power source driven by the driving power source to generate hydraulic pressure, and A transmission 4 having an auxiliary transmission mechanism 30 whose transmission gear ratio is changed according to the engagement state of the friction element (High clutch 33) and the second friction element (Low brake 32) to transmit the driving force of the driving force source to the driving wheels. And a controller 12 for controlling the operation of the engine 1, the mechanical oil pump 10m, and the transmission 4 are used in a vehicle.

The controller 12 is configured as a coast stop control unit that performs a coast stop to stop the engine in the traveling 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 in the engaged state and the Low brake 32 is in the released state during the coast stop.

The controller 12 starts precharging to supply the hydraulic pressure in order to put the Low brake 32 in the engagement preparation state after the stop of the engine 1 is instructed until the drive of the engine 1 is stopped.

According to the embodiment of the present invention, the engine 1 is still rotated by the inertial force and the mechanical oil pump 10m is driven during the period from when the engine 1 is instructed to stop until the driving of the engine 1 is stopped. Precharge of the low brake 32, which is the second friction element, is started. As a result, even if the hydraulic pressure is taken at the start of the precharging, a 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 the slip of the first friction element is suppressed. Therefore, it is possible to suppress the change in longitudinal acceleration of the vehicle from being caused by the torque loss due to the slip of the friction element and the fastening shock accompanying the re-engagement of the slipped friction element, thereby reducing the discomfort given to the driver. When the rotation of the drive source is stopped, that is, when the rotation of the engine 1 is stopped, the rotation of the mechanical oil pump 10m which is the hydraulic pressure source is stopped, and the discharge pressure of the hydraulic pressure source becomes zero. Therefore, in the embodiment of the present invention, the "rotation stop of the hydraulic pressure source" is determined by "the rotation stop of the engine 1".

The controller 12 starts precharging when a stop of the engine 1 is commanded (substantially simultaneously). Thus, by starting the precharging 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 large, the hydraulic pressure generated by the mechanical oil pump 10m (the engine rotation speed Ne is zero While the precharging can be completed), the decrease in oil pressure is suppressed, and the occurrence of the slip of the high clutch 33 which is the first friction element is suppressed. Therefore, it is possible to suppress the change in longitudinal acceleration of the vehicle from being caused by the torque loss due to the slip of the friction element and the fastening shock accompanying the re-engagement of the slipped friction element, thereby reducing the discomfort given to the driver.

The auxiliary transmission mechanism 30 of the transmission 4 has a high speed mode in which the high clutch 33 is in the first state of engagement, and a low speed mode in which the low brake 32 is in the second state of engagement. It is set to the transmission gear ratio on the Low side of the high speed mode.

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

The transmission 4 is provided with a torque converter 2 having a lockup clutch, and when performing a coast stop, the engine 1 is stopped and the lockup clutch is released. With such a configuration, since the lockup clutch and the high clutch 33 do not slip, 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 area to be stopped can be expanded to improve the fuel consumption.

The transmission 4 has a variator 20 which is a continuously variable transmission mechanism capable of changing the transmission gear ratio by changing the winding diameter of the power transmission belt held by the hydraulic pressure supplied to the pulley. Then, 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 detecting that the vehicle is rapidly decelerating. It is configured to

At the time of rapid deceleration of the vehicle, it is necessary to control the through transmission ratio of the transmission 4 to the low side in preparation for restarting after the vehicle is stopped. At this time, in the auxiliary transmission mechanism 30, 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 requires that each pulley be in a rotating state. Therefore, by stopping the precharging at the time of rapid deceleration and using the hydraulic pressure only to return the gear ratio of the variator to the Low side, it is possible to secure the restart after the sudden stop.

The transmission 4 is a mechanical oil pump 10m as a first hydraulic pressure source driven by the engine 1 as a hydraulic pressure source, and an electric oil as a second hydraulic pressure 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 10 e during coast stop control. Thus, 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 gripping force of the variator 20 can be secured.

As mentioned above, although embodiment of this invention was described, the said embodiment is only what showed one of the application examples of this invention, and the meaning which limits the technical scope of this invention to the specific structure of the said embodiment is not.

For example, in the above embodiment, the belt-type continuously variable transmission mechanism is provided as the variator 20. However, the variator 20 is a continuously variable transmission mechanism in which a chain is wound between

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 an input disc and an output disc.

Although the engine 1 which is an internal combustion engine was demonstrated to the example as an example of a driving force source in the said embodiment, it is not limited to this, You may use a motor and another driving force source.

In the above embodiment, the auxiliary transmission mechanism 30 is a transmission mechanism having two gears, first and second, as forward gear positions, but three or more gear stages are used as the auxiliary gear mechanism 30 as forward gear positions. It does not matter as a transmission mechanism which it has. In this case, there is a possibility that another friction element may intervene, but the friction element for achieving the gear ratio on the Low side in preparation for restart upon 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, although the implementation area of the precharging is from the start of coast stop control to the stop of the rotation of the engine 1, the timing of the end of the implementation area of the precharging is necessarily the stop of the rotation of the engine 1. It does not have to be. For example, engine rotation speed Ne> predetermined threshold (threshold by which discharge pressure can be reliably ensured) may be adopted, or line pressure PL> predetermined threshold (threshold by which discharge pressure can be surely ensured). It is good also as a predetermined threshold (threshold by which discharge pressure can be secured reliably)> lapse of predetermined time from the start of coast stop control.

The best mode of the precharge control start timing is the start of the coast stop control. However, the present invention is not limited to this. The precharge control may be started with a delay from the start of the coast stop control. This delay (precharge control start timing) is, for example, as engine rotation speed Ne ≦ predetermined threshold value (threshold value for ensuring discharge pressure), line pressure PL> predetermined threshold value (threshold value for ensuring discharge pressure) It is also good. It may be determined by the elapse of a predetermined time from the start of the coast stop control> a predetermined threshold (a threshold at which the discharge pressure can be reliably ensured).

The present application claims priority based on Japanese Patent Application No. 2012-167320 filed on Jul. 27, 2012 in the Japanese Patent Office. The contents of all of these applications are incorporated herein by reference.

Claims

A driving power source for driving the vehicle,
An oil pressure source driven by the driving power source to generate an oil pressure;
An automatic transmission whose transmission gear ratio is changed according to the engagement state of the first friction element and the second friction element to transmit the driving force of the driving force source to the driving wheels;
A control unit that controls operations of the driving power source, the hydraulic pressure source, and the automatic transmission;
Control device for an automatic transmission in a vehicle comprising
The control unit
A coast stop that outputs a stop command to the driving power source to stop the driving power source when the vehicle is in a traveling state, the first friction element is in the engaged state, and the second friction element is in the released state. Coast stop control unit, which
A friction element control unit configured to control an engagement state of the first friction element and the second friction element;
The friction element control unit is configured to supply hydraulic pressure to the second friction element after the coast stop control unit outputs a stop command of the driving power source and the rotation of the hydraulic pressure source is stopped. Automatic transmission control device to start.
The control device for an automatic transmission according to claim 1,
Starting supply of oil pressure to the second friction element is a precharge control that supplies oil pressure to the second friction element such that the second friction element is in a state just before starting power transmission. Control device of an automatic transmission.
The control device for an automatic transmission according to claim 1 or 2, wherein
The control device for an automatic transmission, wherein the friction element control unit starts supply of hydraulic pressure to the second friction element when the coast stop control unit outputs a stop command of the driving power source.
A control device for an automatic transmission according to any one of claims 1 to 3, wherein
The automatic transmission
The first state in which the first friction element is in the engaged state;
A second state in which the second friction element is in the engaged state;
Have
The control device of the automatic transmission which transmits the driving force of the said driving force source to the said driving wheel in the said 2nd state by the gear ratio by the side of Low rather than the said 1st state.
A control device for an automatic transmission according to any one of claims 1 to 4, wherein
The automatic transmission comprises a torque converter having a lockup clutch,
The control device for an automatic transmission, wherein the coast stop control unit outputs a stop command of the driving power source and releases the lockup clutch.
A control device for an automatic transmission according to any one of claims 1 to 5, wherein
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 control unit
After the coast stop control unit outputs a stop command of the drive power source, the supply of hydraulic pressure to the second friction element is started before the drive of the drive power source is stopped.
A control device of an automatic transmission which stops supply of oil pressure to the 2nd above-mentioned friction element, when it detects that the above-mentioned vehicles are sudden deceleration.
A control device for an automatic transmission according to any one of claims 1 to 6, wherein
The hydraulic pressure source includes a first hydraulic pressure source driven by the driving power source, and a second hydraulic pressure source capable of supplying hydraulic pressure regardless of the driving state of the driving power source.
The control device for an automatic transmission which commands the drive of the second hydraulic pressure source when the coast stop control unit outputs a stop command of the driving power source.
A driving power source for driving the vehicle,
An oil pressure source driven by the driving power source to generate an oil pressure;
An automatic transmission whose transmission gear ratio is changed according to the engagement state of the first friction element and the second friction element to transmit the driving force of the driving force source to the driving wheels;
A control unit that controls the operation of the driving force source, the hydraulic pressure source, and the transmission mechanism;
A method of controlling an automatic transmission in a vehicle comprising:
When the vehicle is in the traveling state, and the first friction element is in the engaged state and the second friction element is in the released state, a command to stop the driving force source is output.
The control method of the automatic transmission which starts supply of oil pressure to said 2nd friction element after rotation of said hydraulic power source is stopped, after stop of said driving power source is commanded.