JP2008179235A - Gear shift control device for hybrid car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a gear shift control device for shifting an automatic transmission in a hybrid car without generating any pull-in shock or engine idling. <P>SOLUTION: When requesting to switch an electric traveling (EV) to hybrid traveling (HEV) mode (engine start) at a time t1, a release side friction element working pressure Po is decreased to a slip holding pressure, and transmission input rotational frequency is made changeable by a motor/generator. At a time t2 where Po=slip holding pressure is satisfied, target motor/generator rotational frequency tNm is increased to engine start rotational frequency Nes, and an engine is started by the motor/generator. At a down-shift request t3, a fastening side friction element working pressures Pc is increased to a return spring equivalent pressure. At an engine start decision t4, the tNm is increased to a (shifted input rotational frequency Ninext+predetermined value α), and at a time t5 where motor/generator rotational frequency Nm (which is the same as engine rotational frequency Ne) following this reaches Ninext, a release side friction element working pressure Po is decreased to 0, and the fastening side friction element working pressure Pc is increased, so that down-shift can be executed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention can be driven not only by the engine but also by power from the motor / generator, and by electric power (EV) mode in which the vehicle travels only by power from the motor / generator, and by power from both the engine and the motor / generator. The present invention relates to a shift control device for a hybrid vehicle having a hybrid travel (HEV) mode capable of traveling.

Conventionally, various types of hybrid drive apparatuses used in the hybrid vehicle as described above have been proposed. As one of them, the one described in Patent Document 1 is known.
The hybrid drive device includes a first clutch that is coupled to a shaft that directs engine rotation to a transmission, includes a motor / generator between the engine and the transmission, and that removably couples the engine and the motor / generator. In addition, the motor / generator and the transmission output shaft have a second clutch and a transmission that are detachably coupled between the motor / generator and the transmission output shaft.

When the hybrid vehicle including such a hybrid drive device releases the first clutch and engages the second clutch, the hybrid vehicle is in an electric travel (EV) mode that travels only by the power from the motor / generator,
When both the first clutch and the second clutch are engaged, a hybrid running (HEV) mode capable of running with power from both the engine and the motor / generator can be set.

In such a hybrid vehicle,
When driving in the former EV mode, the required driving force increases due to acceleration request or accelerator pedal depression, and it is no longer possible to achieve this required driving force with only the motor / generator, so engine output is required If the power storage state of the motor / generator battery deteriorates (the power that can be taken out decreases) and engine output is required, the EV mode is switched to the latter HEV mode. Switching the mode to the HEV mode by starting the engine with a motor / generator by engaging the clutch,
Conversely, while driving in the latter HEV mode, the required driving force decreases due to a deceleration request or accelerator pedal return operation, and this required driving force can be realized only by the motor / generator, so no engine output is required. If the power storage state of the motor / generator battery improves (the power that can be taken out increases) and the engine output becomes unnecessary, the HEV mode is switched to the former EV mode. At this time, the mode is switched to the EV mode by releasing the first clutch and stopping the engine.

  On the other hand, when switching the EV → HEV mode as described above, the mode is switched while the first clutch is engaged and the engine is started by the motor / generator. Therefore, it may be necessary to shift the transmission (downshift).

In response to this shift (downshift) request, EV → HEV mode switching request accompanied by engine start before this, and conversely EV → HEV mode switching request accompanied by engine start later than this. Conventionally, for example, Patent Document 2 describes a shift shock mitigation technique that can be applied even when there is no EV → HEV mode switching request accompanying engine start and only a downshift request is generated. Like,
During downshifting, rotation adjustment control during shifting is performed to match the input rotation speed of the transmission with the input rotation speed after shifting with the motor (which can be calculated back from the current transmission output rotation speed and the gear ratio after shifting). A shift shock mitigation technique has been proposed in which, when the alignment control is finished, the transmission torque capacity of the corresponding shift friction element is set to a value that completes the shift, and the downshift is completed.
JP 2000-255285 A Japanese Patent Laid-Open No. 09-308011

  By the way, in the system that controls the transmission torque capacity of the variable speed friction element, there is a response delay between when the target transmission torque capacity is commanded and when the transmission torque capacity actually reaches a value corresponding to the command. In addition, this response delay varies depending on the temperature environment, deterioration with time, etc., and avoids variations in the timing at which the transmission torque capacity of the shift friction element is completed to a value that completes the downshift. I can't.

Therefore, in the conventional shift shock mitigation technique described above, it is difficult to match the timing at which the transmission torque capacity of the shift friction element is set to a value that completes the downshift to the end timing of the shift rotation matching control. The former timing is too early or delayed with respect to the latter timing.
If the former timing is too early with respect to the latter timing, the gear train in the transmission will tend to be interlocked and braked with respect to the transmission case, causing a pulling shock due to a temporary decrease in wheel drive torque. .
On the contrary, if the former timing is delayed with respect to the latter timing, the gear train in the transmission tends to be neutralized temporarily, causing a temporary engine blow-off, and a blow-off at the end of the subsequent downshift. A shock due to the inertia of the minute occurs.

According to the present invention, in the hybrid vehicle of the type described above, the downshift of the transmission torque capacity of the transmission friction element is completed in a state where the transmission input rotational speed is made larger than the post-shifting rotational speed by the motor / generator. If the value is set to a low value, it is possible to avoid the above-mentioned problems related to the drawing shock, and since the engine is restricted from increasing in the number of revolutions by the motor / generator, the above-mentioned problems related to idling of the engine also occur. From the point of view that there is no
The object of the present invention is to propose a shift control device for a hybrid vehicle that embodies this idea and that can solve all the problems that are unavoidable with the conventional downshift shift shock technology.

For this purpose, the shift control device for a hybrid vehicle according to the present invention has the following configuration described in claim 1.
First, to explain the premise hybrid vehicle,
An engine and a motor / generator are provided as power sources, a first clutch capable of changing the transmission torque capacity is interposed between the engine and the motor / generator, and the transmission torque capacity can be changed between the motor / generator and the drive wheel. 2 Clutch and transmission are arranged in series and interposed,
By stopping the engine, releasing the first clutch and engaging the second clutch, it is possible to select the electric travel mode using only the power from the motor / generator. By engaging the first clutch in this electric travel mode, the motor By starting the engine with the / generator, the mode can be switched to the hybrid travel mode by the power from both the engine and the motor / generator.

The present invention relates to such a hybrid vehicle,
When the transmission is downshifted, the transmission input speed of the transmission can be changed by the motor / generator by controlling the transmission torque capacity of the transmission friction element that controls the downshift. The shift friction element is configured to have a transmission torque capacity for performing the downshift after the number is made larger than the rotation speed after the shift.

According to the above-described shift control apparatus for a hybrid vehicle according to the present invention,
At the time of downshift, the transmission input speed can be changed by the motor / generator by controlling the transmission torque capacity of the corresponding shift friction element, and in this state, the transmission input speed is made larger than the post-shift speed by the motor / generator. In order to make the speed change friction element the transmission torque capacity to be downshifted,
When the transmission friction element has the transmission torque capacity for downshifting, the transmission input rotational speed is larger than the post-shifting rotational speed, thereby avoiding the above-described problems related to the pulling shock that may occur in the conventional device. Needless to say, the problem with the above-mentioned engine blow-off that may occur in the conventional apparatus is caused by the fact that the engine speed is limited by the motor / generator and does not exceed the motor / generator speed. Does not occur.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a front engine / rear wheel drive hybrid vehicle equipped with a hybrid drive device to which the speed change control device of the present invention can be applied, where 1 is an engine and 2 is a drive wheel (rear wheel).
In the power train of the hybrid vehicle shown in FIG. 1, the automatic transmission 3 is arranged in tandem at the rear of the engine 1 in the longitudinal direction of the vehicle in the same manner as a normal rear wheel drive vehicle, and the engine 1 (crankshaft 1a) is rotated. A motor / generator 5 is provided in combination with the shaft 4 that transmits to the input shaft 3a of the automatic transmission 3.

The motor / generator 5 functions as a motor or a generator (generator), and is disposed between the engine 1 and the automatic transmission 3.
More specifically, a first clutch 6 is inserted between the motor / generator 5 and the engine 1 and, more specifically, between the shaft 4 and the engine crankshaft 1a, and the engine 1 and the motor / generator 5 are disconnected by the first clutch 6. Join as possible.
Here, the transmission torque capacity of the first clutch 6 can be changed continuously or stepwise. For example, the transmission torque capacity can be changed by continuously controlling the clutch hydraulic oil flow rate and the clutch hydraulic pressure with a proportional solenoid. It consists of a simple wet multi-plate clutch.

More specifically, a second clutch 7 is inserted between the motor / generator 5 and the automatic transmission 3 and more specifically between the shaft 4 and the transmission input shaft 3a. The second clutch 7 causes the motor / generator 5 and the automatic transmission to be inserted. 3 are separably connected.
Similarly to the first clutch 6, the second clutch 7 can change the transmission torque capacity continuously or stepwise. For example, the proportional hydraulic solenoid can continuously control the clutch hydraulic fluid flow rate and the clutch hydraulic pressure to transmit torque. It consists of a wet multi-plate clutch whose capacity can be changed.

The automatic transmission 3 is the same as that described in pages C-9 to C-22 on the "Skyline New Car (CV35) Manual" issued by Nissan Motor Co., Ltd. in January 2003. By selectively engaging or releasing a shift friction element (such as a clutch or a brake), a transmission path (shift stage) is determined by a combination of engagement and release of these shift friction elements.
Therefore, the automatic transmission 3 shifts the rotation from the input shaft 3a at a gear ratio corresponding to the selected shift speed and outputs it to the output shaft 3b.
This output rotation is distributed and transmitted to the left and right rear wheels 2 by the differential gear device 8 and used for traveling of the vehicle.
However, it goes without saying that the automatic transmission 3 is not limited to the stepped type as described above, and may be a continuously variable transmission.

The automatic transmission 3 is as shown in FIG. 4, and the outline thereof will be described below.
The input / output shafts 3a and 3b are arranged in a coaxial butt relationship, and the front planetary gear set Gf, the center planetary gear set Gm, and the rear planetary gear set Gr are sequentially arranged on the input / output shafts 3a and 3b from the engine 1 (motor / generator 5) side. These are the main components of the planetary gear transmission mechanism in the automatic transmission 3.

The front planetary gear set Gf closest to the engine 1 (motor / generator 5) is a simple planetary gear comprising a front sun gear Sf, a front ring gear Rf, a front pinion Pf meshing with the front sun gear Sf, and a front carrier Cf rotatably supporting the front pinion. A gear set,
Next, the center planetary gear set Gm close to the engine 1 (motor / generator 5) includes a center sun gear Sm, a center ring gear Rm, a center pinion Pm meshing with the center sun gear Sm, and a center carrier Cm that rotatably supports the center pinion. A planetary gear set,
The rear planetary gear set Gr farthest from the engine 1 (motor / generator 5) is a simple planetary gear set comprising a rear sun gear Sr, a rear ring gear Rr, a rear pinion Pr meshing with the rear sun gear Sr, and a rear carrier Cr that rotatably supports the rear pinion. To do.

  Front friction Fr / B, input clutch I / C, high-and-low reverse clutch H & LR / C, direct clutch D / C, reverse, as the transmission friction elements that determine the transmission path (speed stage) of the planetary gear transmission mechanism Brake R / B, low coast brake LC / B, and forward brake FWD / B are provided, and these are three one-way clutches: three-speed one-way clutch 3rd / OWC, one-speed one-way clutch 1st / OWC and forward one-way clutch Together with the FWD / OWC, the planetary gear transmission mechanism of the automatic transmission 3 is configured in correlation with the above-described components of the planetary gear group Gf, Gm, Gr as follows.

The front ring gear Rf is coupled to the input shaft 3a, and the center ring gear Rm can be appropriately coupled to the input shaft 3a by the input clutch I / C.
The front sun gear Sf is prevented from rotating in the direction opposite to the rotation direction of the engine 1 via the 3-speed one-way clutch 3rd / OWC, and the front brake Fr / disposed in parallel to the 3-speed one-way clutch 3rd / OWC. B can be fixed as appropriate.
Front carrier Cf and rear ring gear Rr are coupled to each other, and center ring gear Rm and rear carrier Cr are coupled to each other.

  The center carrier Cm is coupled to the output shaft 3b, and the center sun gear Sm does not rotate in the direction opposite to the rotation direction of the engine 1 with respect to the rear sun gear Sr via the first-speed one-way clutch 1st / OWC between the center sun gear Sm and the rear sun gear Sr. In addition, the center sun gear Sm and the rear sun gear Sr can be connected to each other by the high and low reverse clutch H & LR / C.

The rear sun gear Sr and the rear carrier Cr can be coupled by a direct clutch D / C, and the rear carrier Cr can be appropriately fixed by a reverse brake R / B.
The center sun gear Sm is further prevented by the forward brake FWD / B and the forward one-way clutch FWD / OWC from rotating in the reverse direction of the engine 1 when the forward brake FWD / B is engaged, and the low coast brake. LC / B can be fixed as appropriate, so low coast brake LC / B is provided in parallel with forward brake FWD / B and forward one-way clutch FWD / OWC.

  The power transmission train of the planetary gear transmission mechanism has seven shift friction elements Fr / B, I / C, H & LR / C, D / C, R / B, LC / B, FWD / B, and three one-way. With the selective engagement shown in Fig. 5 for clutches 3rd / OWC, 1st / OWC, FWD / OWC as indicated by ◯ and ● (when engine braking), forward first speed (1st), forward second speed (2nd), The third forward speed (3rd), the fourth forward speed (4th), the fifth forward speed (5th), and the reverse speed stage (Rev) can be obtained.

  In the power train of FIG. 1 including the automatic transmission 3 described above, when the electric travel (EV) mode used at low load / low vehicle speed including when starting from a stopped state is required, the first clutch 6 Is released, the second clutch 7 is engaged, and the automatic transmission 3 is in a power transmission state.

When the motor / generator 5 is driven in this state, only the output rotation from the motor / generator 5 reaches the transmission input shaft 3a, and the automatic transmission 3 changes the rotation to the input shaft 3a to the selected shift speed. The speed is changed according to the speed and output from the transmission output shaft 3b.
Then, the rotation from the transmission output shaft 3b reaches the rear wheel 2 via the differential gear device 8, and the vehicle can be electrically driven (EV traveling) only by the motor / generator 5.

When hybrid driving (HEV driving) mode used when driving at high speeds, during heavy loads, or when the amount of power that can be taken out by the battery is low, both the first clutch 6 and the second clutch 7 are engaged, The automatic transmission 3 is brought into a power transmission state.
In this state, the output rotation from the engine 1, or both the output rotation from the engine 1 and the output rotation from the motor / generator 5 reach the transmission input shaft 3a, and the automatic transmission 3 is connected to the input shaft 3a. Is rotated according to the currently selected shift speed and output from the transmission output shaft 3b.
The rotation from the transmission output shaft 3b then reaches the rear wheel 2 via the differential gear device 8, and the vehicle can be hybrid-driven (HEV-driven) by both the engine 1 and the motor / generator 5.

  In such HEV traveling, when the engine 1 is operated with the optimal fuel efficiency, if the energy becomes surplus, the surplus energy is converted into electric power by operating the motor / generator 5 as a generator by this surplus energy, and this generated power is converted into electric power. By accumulating power to be used for driving the motor of the motor / generator 5, the fuel consumption of the engine 1 can be improved.

In FIG. 1, the second clutch 7 that detachably couples the motor / generator 5 and the drive wheel 2 is interposed between the motor / generator 5 and the automatic transmission 3,
As shown in FIG. 2, even if the second clutch 7 is interposed between the automatic transmission 3 and the differential gear device 8, the same function can be achieved.

In addition, in FIG. 1 and FIG. 2, a dedicated second clutch 7 is added before or after the automatic transmission 3,
Instead of this, as the second clutch 7, as shown in FIG. 3, a shift friction element for selecting a forward shift stage existing in the automatic transmission 3, for example, a high and low reverse clutch H & LR / C may be used. Good.
In this case, in addition to the second clutch 7 performing the above-described mode selection function, the automatic transmission is brought into a power transmission state by shifting to the corresponding gear stage when engaged to perform this function. The second clutch is not necessary and is very advantageous in terms of cost.

The engine 1, the motor / generator 5, the first clutch 6, and the second clutch 7 constituting the power train of the hybrid vehicle shown in FIGS. 1 to 3 are controlled by a system as shown in FIG.
In the following description, it is assumed that the power train is as shown in FIG. 3 (existing speed change friction element in the automatic transmission 3 as the second clutch 7).

  The control system of FIG. 6 includes an integrated controller 20 that integrally controls the operating point of the power train. The operating point of the power train is set to the target engine torque tTe and the target motor / generator torque tTm (or the target motor / generator rotation speed tNm). ), A target transmission torque capacity tTc1 (first clutch command pressure tPc1) of the first clutch 6, and a target transmission torque capacity tTc2 (second clutch command pressure tPc2) of the second clutch 7.

In order to determine the operating point of the power train, the integrated controller 20
A signal from the engine rotation sensor 11 for detecting the engine speed Ne;
A signal from the motor / generator rotation sensor 12 for detecting the motor / generator rotation speed Nm;
A signal from the input rotation sensor 13 for detecting the transmission input rotation speed Ni,
A signal from the output rotation sensor 14 that detects the transmission output rotation speed No,
A signal from an accelerator opening sensor 15 for detecting an accelerator pedal depression amount (accelerator opening APO) representing a required load state of the engine 1;
A signal from a storage state sensor 16 that detects a storage state SOC (carryable power) of the battery 9 that stores power for the motor / generator 5 is input.

  Among the sensors described above, the engine rotation sensor 11, the motor / generator rotation sensor 12, the input rotation sensor 13, and the output rotation sensor 14 can be arranged as shown in FIGS.

The integrated controller 20 is a driving mode in which the driving force of the vehicle desired by the driver can be realized from the accelerator opening APO, the battery storage state SOC, and the transmission output rotational speed No (vehicle speed VSP) among the above input information. (EV mode, HEV mode) is selected, target engine torque tTe, target motor / generator torque tTm (or target motor / generator speed tNm), target first clutch transmission torque capacity tTc1 (first clutch command pressure tPc1) , And a target second clutch transmission torque capacity tTc2 (second clutch command pressure tPc2).
The target engine torque tTe is supplied to the engine controller 21, and the target motor / generator torque tTm (or the target motor / generator rotation speed tNm) is supplied to the motor / generator controller 22.

The engine controller 21 controls the engine 1 so that the engine torque Te becomes the target engine torque tTe.
The motor / generator controller 22 sets the battery 9 and the inverter so that the torque Tm of the motor / generator 5 becomes the target motor / generator torque tTm (or the rotational speed Nm of the motor / generator 5 becomes the target motor / generator rotational speed tNm). The motor / generator 5 is controlled via 10.
The integrated controller 20 generates solenoid currents corresponding to the target first clutch transmission torque capacity tTc1 (first clutch command pressure tPc1) and the target second clutch transmission torque capacity tTc2 (second clutch command pressure tPc2). 2 Supply to the hydraulic control solenoid (not shown) of the clutch 7 so that the transmission torque capacity Tc1 (first clutch pressure Pc1) of the first clutch 6 matches the target transmission torque capacity tTc1 (first clutch command pressure tPc1) Further, the first clutch 6 and the second clutch 7 are set such that the transmission torque capacity Tc2 (second clutch pressure Pc2) of the second clutch 7 matches the target second clutch transmission torque capacity tTc2 (second clutch command pressure tPc2). The fastening force is controlled individually.

  The integrated controller 20 receives a mode change (engine start) request from the electric drive (EV) mode to the hybrid drive (HEV) mode, and performs a downshift of the automatic transmission 3 during the associated control. When the request is generated, EV → HEV mode switching (engine start) control and downshift control of the automatic transmission 3 are performed based on the time chart shown in FIG.

  This Fig. 7 shows that the EV → HEV mode switching (engine start) request occurs at the instant t1, as a result of slowly depressing the accelerator pedal to increase the vehicle acceleration G from the instant t0 during EV running as shown in the figure. 6 is a time chart when a downshift request for the automatic transmission 3 is generated at an instant t3 during control.

At the instant t1 when EV → HEV mode switching (engine start) is requested, the operating pressure Po of the disengagement side frictional element, which is one of the downshifting frictional elements, is increased from the line pressure, which is the maximum value, and the transmission input speed is motor / Decrease to the slip maintaining pressure that can be changed by the generator 5.
The first clutch 6 is engaged at the instant t2 when the release-side frictional friction element operating pressure Po is reduced to the slip maintaining pressure, and the engine can be started from the target motor / generator rotation speed tNm from the input rotation speed Nicur before transmission. By increasing the speed to Nes and controlling the motor / generator 5 so that the actual motor / generator speed Nm follows the engine startable speed Nes, the engine 1 is apparent from the change over time of the engine speed Ne. Cranking with the motor / generator 5
It is noted that the unstable torque during this time becomes an engine start shock toward the wheels, and can be mitigated by the slip of the release side speed change friction element obtained due to the decrease in the release side speed change friction element working pressure Po. it can.

When the downshift request of the automatic transmission 3 occurs at the instant t3 during the cranking of the engine 1, the operating pressure Pc of the engagement side shift friction element, which is one of the shift friction elements for the downshift, is changed to the engagement side shift. The friction element is quickly raised from 0 under precharge control to a return spring equivalent pressure that is brought into a state just before fastening from the released state.
In the meantime, the cranking of the engine 1 by the rotation control of the motor / generator 5 is continued, the engine 1 is finally started by the further increase of the engine speed Ne, and the EV → HEV mode switching is completed.

  With this start, the engine 1 starts a self-sustained operation and generates a drive torque (engine torque Te ≧ 0), and the engine speed Ne reaches the motor / generator speed Nm (Ne ≧ Nm). ) At the instant t4, the target motor / generator rotation speed tNm is increased from the engine startable rotation speed to a value (Ninext + α) that is higher than the input rotation speed Ninext after shifting by a predetermined value α, and the motor / generator rotation speed Nm The rotation of the motor / generator 5 is controlled so as to follow the target value tNm.

Note that the target motor / generator rotation speed tNm before and after the engine start determination instant t4, that is, the engine startable rotation speed and a value raised by a predetermined value α from the post-shift input rotation speed Ninext (Ninext + α) The greater the difference between the two, the shorter the time required for the transmission input rotational speed to reach the post-shifting input rotational speed Ninext. Thus, the amount of increase is set according to the time required to reach the input rotational speed Ninext after shifting.
In addition, the self-sustained operation of the engine 1 increases the vehicle acceleration G from the moment t4 as shown in the figure by cooperating with the motor / generator 5.

By increasing the target motor / generator speed tNm from the engine startable speed to (Ninext + α) at the engine start determination instant t4, the motor / generator speed Nm (engine speed Ne At the instant t5 when the input speed reaches the next rotation speed Ninext after shifting, the disengagement side shifting friction element operating pressure Po is decreased from the slip maintaining pressure to 0 and the engagement side shifting friction element operating pressure Pc is increased from the return spring equivalent pressure. Then, a downshift corresponding to the shift command at the instant t3 is performed by switching the shift friction element that shifts the torque sharing ratio from the disengagement side shift friction element to the engagement side shift friction element.
This downshift is performed with the motor / generator rotation speed Nm (transmission input rotation speed) set to a value in the vicinity of the post-shift input rotation speed Ninext, so that a large shift shock can be avoided. it can.

  During the downshift, the target motor / generator rotational speed tNm is gradually decreased from (Ninext + α) to the post-shift input rotational speed Ninext, and the motor / generator rotational speed Nm (decreased to follow this) At the instant t6 when the engine speed Ne) reaches the post-shift input speed Ninext, the rotation control of the motor / generator 5 aimed at by the present invention started from the instant t2 is terminated.

By the way, in the present embodiment, at the time of downshift, the transmission input rotational speed can be changed by the motor / generator 5 by controlling the transmission torque capacity (operating pressure Po) of the corresponding disengagement side shift friction element, and in this state the motor / Transfer torque capacity (downshifting is performed on the disengagement side shift friction element and the engagement side shift friction element after the generator 5 has made the transmission input rotation speed larger than the post-shift rotation speed Ninext by a predetermined value α (set to Ninext + α) ( Operating pressure Po, Pc)
The transmission input rotation speed (motor / generator rotation speed Nm and engine rotation speed Ne) after the instant t5 when the shift friction element becomes the transmission torque capacity at which the downshift is performed is larger than the post-shift rotation speed Ninext ( In addition to avoiding the problem related to the pulling shock caused by the interlock described above, the increase in the engine speed Ne is limited by the motor / generator 5 and the motor / generator speed Nm is avoided. Is not exceeded, there is no problem with engine blow-off such that the engine speed Ne exceeds (Ninext + α).

As shown in FIG. 7, when an EV → HEV mode switching (engine start) request is first generated (momentary t1) and then a downshift request is generated (instantaneous t3), the former EV → HEV first as described above. Transmission torque capacity that allows mode switching (engine start) and engine start determination (Te ≧ 0 and Ne ≧ Nm determination) to downshift the disengagement side shift friction element and the engagement side shift friction element after instant t4 In order to perform downshift as (operating pressure Po, Pc),
Even if the EV / HEV mode switching (engine start) and the input rotation matching control for preventing downshift shock are performed simultaneously, even if the motor / generator torque is insufficient, the motor / generator torque is insufficient by causing these to be performed sequentially. This lack of motor / generator torque can cause the release-side shift friction element in the slip state to be inadvertently engaged and cause a shock or engine start delay (mode switching response delay). The trouble can be avoided.

  FIG. 8 shows a mode switch (engine start) from the electric travel (EV) mode to the hybrid travel (HEV) mode while there is a downshift request of the automatic transmission 3 and the associated shift control is performed. The downshift control and EV → HEV mode switching (engine start) control of the automatic transmission 3 executed by the integrated controller 20 when a request occurs are shown.

  This figure 8 shows that as a result of slowly depressing the accelerator pedal during EV running in the coasting state that was released without depressing the accelerator pedal, a downshift request for the automatic transmission 3 occurred at instant t1, and shift control for that 7 is a time chart when a request for EV → HEV mode switching (engine start) is generated at an instant t2 during the operation.

  At the time of downshift request t1, the operating pressure Po of the release-side shift friction element, which is one of the downshift shift friction elements, is reduced from the maximum line pressure to 0 to release the shift friction element. The operating pressure Pc of the engagement side shifting friction element, which is one of the downshifting shifting friction elements, is increased from 0 to the slip maintaining pressure at which the transmission input rotational speed can be changed by the motor / generator 5. The shift control corresponding to the up / downshift request is started, and the transmission input rotation speed can be changed by the rotation control of the motor / generator 5 while preventing the transmission from being in the neutral state.

  At the start of this downshift control, the target motor / generator rotation speed tNm is raised from the input rotation speed Nicur before shifting to a predetermined value α higher than the input rotation speed Ninext after shifting (Ninext + α) at the downshift request instant t1. The motor / generator 5 is rotationally controlled so that the actual motor / generator rotational speed Nm follows the raised rotational speed (Ninext + α).

During the downshift control, the shift control is interrupted at the instant t2 when the request for EV → HEV mode switching (engine start) occurs, and priority is given to EV → HEV mode switching (engine start) as follows.
In other words, at the instant t2 when EV → HEV mode switching (engine start) is requested, the first clutch 6 is engaged to give priority to this request, and the target motor / generator rotation speed tNm is started from the above-mentioned raised rotation speed (Ninext + α). The rotational speed of the motor / generator 5 is controlled so that the actual motor / generator rotational speed Nm follows this engine startable rotational speed by reducing the rotational speed to a possible rotational speed.

With the engagement of the first clutch 6 and the rotation control of the motor / generator 5, the engine is coupled with the maintenance of slippage of the engagement-side speed change friction element (maintaining a state in which the transmission input rotation speed can be changed by the motor / generator 5). 1 is cranked by the motor / generator 5 as apparent from the change with time of the engine speed Ne.
It is noted that the unstable torque during this period becomes an engine start shock toward the wheels, and is mitigated by the slip of the engagement side speed change friction element obtained due to the slip maintaining pressure of the engagement side speed change friction element operating pressure Pc. be able to.

By continuing the cranking of the engine 1 by the rotation control of the motor / generator 5, the engine 1 is finally started by further increasing the engine speed Ne, and the EV → HEV mode switching is completed.
With this start, the engine 1 starts a self-sustained operation and generates a drive torque (engine torque Te ≧ 0), and the engine speed Ne reaches the motor / generator speed Nm (Ne ≧ Nm). ) At the instant t3, the target motor / generator rotational speed tNm is again increased from the engine startable rotational speed to the above-mentioned raised rotational speed (Ninext + α), so that the motor / generator rotational speed Nm follows this target value tNm. By controlling the rotation of the generator 5, the shift control corresponding to the downshift command at the instant t1 is resumed.

By increasing the target motor / generator speed tNm from the engine startable speed to the raised speed (Ninext + α) at the engine start determination instant t3, the motor / generator speed Nm (engine speed) is increased to follow this. At the instant t4 when the input rotational speed Ninext reaches the post-shift input speed Ninext, the engagement-side shift friction element operating pressure Pc is increased from the slip maintaining pressure to the line pressure, and the engagement-side shift friction element is engaged to release it. In combination with the release of the side shift friction element, a downshift corresponding to the shift command at the instant t1 is performed.
This downshift is performed with the motor / generator rotation speed Nm (transmission input rotation speed) set to a value in the vicinity of the post-shift input rotation speed Ninext, so that a large shift shock can be avoided. it can.

  During this downshift, the target motor / generator rotation speed tNm is gradually decreased from the raised rotation speed (Ninext + α) to the post-shift input rotation speed Ninext, and the motor / generator rotation is decreased so as to follow this. At the instant t5 when the number Nm (same as the engine rotational speed Ne) reaches the post-shift input rotational speed Ninext, the rotation control of the motor / generator 5 targeted by the present invention started from the instant t1 is terminated.

Even in this embodiment, at the time of downshifting, the transmission input rotational speed can be changed by the motor / generator 5 by controlling the transmission torque capacity (operating pressure Pc) of the corresponding engagement-side speed change friction element. Transfer torque capacity (downshifting is performed on the disengagement side shift friction element and the engagement side shift friction element after the generator 5 has made the transmission input rotation speed larger than the post-shift rotation speed Ninext by a predetermined value α (set to Ninext + α) ( Operating pressure Po, Pc)
The transmission input rotation speed (motor / generator rotation speed Nm and engine rotation speed Ne) after the instant t4 when the shift friction element becomes the transmission torque capacity for performing the downshift is larger than the post-shift rotation speed Ninext ( In addition to avoiding the problem related to the pull-in shock caused by the interlock described above, the increase in the engine speed Ne is restricted by the motor / generator 5 so that the motor / generator speed Nm can be avoided. Is not exceeded, there is no problem with engine blow-off such that the engine speed Ne exceeds (Ninext + α).

As shown in FIG. 8, when a downshift request is first generated (momentary t1) and then an EV → HEV mode switching (engine start) request is generated (instantaneous t2), the speed change based on the former request is performed as described above. The control is interrupted at the instant t2 when the latter EV → HEV mode switching (engine start) request occurs, and this EV → HEV mode switching (engine start) is prioritized and executed, and engine start determination (Te ≧ 0, And Ne ≧ Nm judgment) In order to perform the downshift with the transmission torque capacity (operating pressures Po, Pc) in which the disengagement side shift friction element and the engagement side shift friction element are downshifted after the instant t3,
Even if the input rotation matching control for downshift shock prevention and EV → HEV mode switching (engine start) are performed at the same time, even if the motor / generator torque is insufficient, the motor / generator torque is performed sequentially in order of priority. Insufficient motor / generator torque will cause the slipping engagement side shift friction element to be inadvertently engaged and cause a shock or engine start delay (mode switching response delay) Can be avoided.

1 is a schematic plan view showing a power train of a hybrid vehicle to which a shift control device of the present invention can be applied. FIG. 5 is a schematic plan view showing a power train of another hybrid vehicle to which the speed change control device of the present invention can be applied. FIG. 9 is a schematic plan view showing a power train of still another hybrid vehicle to which the shift control device of the present invention can be applied. FIG. 4 is a skeleton diagram showing an automatic transmission in the power train shown in FIGS. FIG. 5 is an engagement logic diagram showing a relationship between a combination of engagement of shift friction elements in the automatic transmission shown in FIG. 4 and a selected shift stage of the automatic transmission. FIG. 4 is a block diagram showing a control system for the power train shown in FIG. 5 is an operation time chart of downshift control and EV → HEV mode switching control executed when the integrated controller in the control system is instructed in the order of downshift and EV → HEV mode switching. 5 is an operation time chart of EV → HEV mode switching control and downshift control executed when the integrated controller in the control system is instructed in the order of EV → HEV mode switching and downshifting.

Explanation of symbols

1 Engine 2 Drive wheel (rear wheel)
3 Automatic transmission 4 Transmission shaft 5 Motor / generator 6 First clutch 7 Second clutch 8 Differential gear device 9 Battery
10 Inverter
11 Engine rotation sensor
12 Motor / generator rotation sensor
13 Transmission input rotation sensor
14 Transmission output rotation sensor
15 Accelerator position sensor
16 Battery charge sensor
20 Integrated controller
21 Engine controller
22 Motor / generator controller

Claims (4)

An engine and a motor / generator are provided as power sources, a first clutch capable of changing the transmission torque capacity is interposed between the engine and the motor / generator, and the transmission torque capacity can be changed between the motor / generator and the drive wheel. 2 Clutch and transmission are arranged in series and interposed,
By stopping the engine, releasing the first clutch and engaging the second clutch, it is possible to select the electric travel mode using only the power from the motor / generator. By engaging the first clutch in this electric travel mode, the motor In a hybrid vehicle that can be switched to hybrid driving mode by power from both the engine and motor / generator by starting the engine with a generator
When the transmission is downshifted, the transmission input speed of the transmission can be changed by the motor / generator by controlling the transmission torque capacity of the transmission friction element that controls the downshift. A shift control apparatus for a hybrid vehicle, wherein the shift friction element is configured to have a transmission torque capacity for performing the downshift after the number is made larger than the rotation speed after shift. In the transmission control device according to claim 1,
The amount of rotation added by which the transmission input rotation speed is made larger than the rotation speed after the shift by the motor / generator is set as the rotation addition amount necessary for the transmission input rotation speed to reach the rotation speed after the shift in the target time. A shift control apparatus for a hybrid vehicle characterized by the above. In the shift control device according to claim 1 or 2,
Prior to the transmission downshift request, when a mode switching request from the electric travel mode to the hybrid travel mode with engine start occurs, the engine is ready to use the engine torque as the drive torque. A hybrid vehicle shift control device characterized in that the transmission input rotational speed is made larger than the post-shift rotational speed later, and then the shift friction element has a transmission torque capacity for performing the downshift. . In the transmission control device according to any one of claims 1 to 3,
If a mode switching request from the electric travel mode to the hybrid travel mode accompanied by the engine start occurs after the downshift request, the downshift is interrupted when the mode switch request is generated, and the engine start is given priority. After the engine is ready to use the engine torque as the drive torque, the transmission input rotational speed is made larger than the post-shift rotational speed, and then the shift friction element is subjected to the downshift. A shift control apparatus for a hybrid vehicle, characterized by comprising:

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