JP2010149560A - Engine start control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine start control device carrying out engine start processing along with upshifting when engine start is requested during the upshifting of an automatic transmission. <P>SOLUTION: When upshifting is necessary since the engine start is requested at t1 according to increase in accelerator opening, torque capacity tTc2 of a transmission friction element on the side released in upshifting is set to a value meeting engine starting time target driving torque, and the number of motor revolutions Nm is increased by a slip. At t2 when the torque capacity tTc2 becomes the engine starting time target driving torque, torque capacity tTc1 of a first clutch is set to a value to achieve an engagement starting state, and control is carried out so that the number of motor revolutions Nm becomes an engine starting target number Nm. After starting, the first clutch is completely engaged when the torque capacity tTc1 becomes a maximum value, and a second clutch is released. The torque capacity tToff of a transmission friction element on the side released in downshifting is kept to a value in downshifting prediction. In this way, upshifting is carried out along with engine starting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes an engine and a motor as a power source, a first clutch is interposed between the engine and the motor, a second clutch is interposed between the motor and the driving wheel, and the second clutch is provided between the motor and the driving wheel. The present invention relates to an engine start control device for a parallel hybrid vehicle that uses a shift friction element in an automatic transmission, and particularly when an engine start request is generated during an upshift of the automatic transmission, The present invention relates to an engine start control device capable of completing a high response without causing a shock.

The hybrid drive device used in the hybrid vehicle as described above has already been proposed in Patent Document 1 by the applicant of the present application.
This hybrid drive unit can select the electric travel (EV) mode only by the power from the motor / generator by releasing the first clutch and engaging the second clutch, and both the first clutch and the second clutch are engaged. By doing so, it is possible to select a hybrid running (HEV) mode by power from both the engine and the motor / generator.

Therefore, when switching the mode from the electric drive (EV) mode to the hybrid drive (HEV) mode, it is necessary to start the engine, and conversely, when switching the mode from the hybrid drive (HEV) mode to the electric drive (EV) mode. The engine must be stopped.
When starting the engine at the time of switching the mode from the former EV mode to the HEV mode, the engine is started with the power from the motor / generator by engaging and engaging the first clutch while slipping the second clutch.

  By the way, Patent Document 1 suggests the following technique for engine start control when the above-described mode switching from EV mode to HEV mode accompanying engine start and shifting of the automatic transmission are required at the same time. Yes.

In other words, when the accelerator pedal depression is issued, the EV → HEV mode switching command accompanied by the engine start is issued, and then the automatic transmission downshift command is issued.
First, the first clutch is brought into a state immediately before the start of engagement, and when the set time has elapsed, the motor / generator torque is increased for starting the engine.
As the motor / generator torque increases, the second clutch starts to slip and the motor / generator rotational speed increases, and the slip amount of the second clutch (the increase amount of the motor / generator rotational speed) reaches a predetermined value. Then, the first clutch is started to be engaged and the engine is started by cranking.

At this time, the downshift release side friction element that is changed from the engaged state to the released state at the time of downshift is used as the second clutch, and the transmission torque capacity is reduced to the torque capacity for the second clutch, and the downshift is performed. At the time of shifting, the shifting side frictional element at the time of downshifting, which is brought into the engaged state from the released state, is brought into a state immediately before the engagement.
When it is determined that the downshift has been completed by the release progress of the release side shifting friction element at the time of downshift and the engagement progress of the engagement side speed change friction element at the time of downshift, the release side shifting element at the time of downshift is completely released. At the same time, the down-shifting is completed by completely engaging the engagement side shifting friction element during downshifting.
JP 2007-261498 A

However, Patent Document 1 does not propose any engine start control technique when a mode switching request from the EV mode to the HEV mode accompanying engine start occurs during the upshift of the automatic transmission.
At this time, generally, the upshift process of the preceding automatic transmission is first performed, and after this process is completed, the mode switching (engine start) process from the EV mode to the HEV mode is usually performed.

Therefore, when an EV → HEV mode switching request from the EV mode to the HEV mode is generated during the upshift of the automatic transmission, the EV → HEV mode switching (engine start) is not started unless the upshift of the automatic transmission is completed. .
For this reason, it is inevitable that the EV → HEV mode switching (engine start) is largely delayed from the required timing.
Such a delay in the response of the EV → HEV mode switching (engine start) causes a problem that the drivability is deteriorated due to insufficient power.

  In addition, the automatic transmission upshift and EV → HEV mode switching (engine start) are performed with a time lag, and the former upshift shock and the latter EV → HEV Shocks due to mode switching (engine start) occur individually with a time lag, and two shocks occur continuously, which is not preferable.

  In the present invention, when the engine start request for EV → HEV mode switching is in the upshift process of the automatic transmission, the engine can be started in parallel with the upshift process. An object of the present invention is to propose an engine start control device for a hybrid vehicle that has been eliminated.

For this purpose, the engine start control device for a hybrid vehicle according to the present invention is configured as described in claim 1.
First, a hybrid vehicle as a premise will be described. This vehicle includes an engine and a motor / generator as power sources, a first clutch is interposed between the engine and the motor / generator, and a second clutch is interposed between the motor / generator and the driving wheels. A clutch is interposed, and as this second clutch, a shift friction element carrying power in the automatic transmission interposed between the motor / generator and the drive wheels is used.

  Such a hybrid vehicle can select the electric travel mode only by the power from the motor / generator by releasing the first clutch and engaging the second clutch, and the engine by engaging both the first clutch and the second clutch. It is possible to select a hybrid travel mode using power from both the motor and the generator.

  In addition, when switching from the electric travel mode with engine start to the hybrid travel mode, during traveling in the electric travel mode, the first clutch is engaged while the second clutch is slipped, so that the motor / generator It is possible to switch the mode from the electric travel mode to the hybrid travel mode by starting the engine with power.

  The engine start control device of the present invention, for such a hybrid vehicle, the following upshift detection means, upshift EV → HEV mode switching request detection means, upshift engagement side shift friction element control means, An upshift release side shifting friction element control means is provided.

The upshift detection means detects that the automatic transmission is upshifting.
The upshift EV → HEV mode switching request detection means detects that there has been a mode switching request from the electric travel mode with engine start to the hybrid travel mode while the upshift detection means detects that the upshift is being performed. To do.

  The up-shift engagement frictional element control means is configured so that when the up-shift EV → HEV mode switching request detecting means detects the electric driving mode during the up-shift → hybrid driving mode switching request, The upshift engagement side shifting friction element that is brought into the engaged state is the second clutch, and the transmission torque capacity of the friction element is set to a target drive torque equivalent value at the time of engine start.

  The release-side shift friction element control means during the upshift is released from the engaged state during the upshift of the automatic transmission during the control of the transmission torque capacity of the engagement-side shift friction element during the upshift by the upshift engagement friction element control means. The transmission torque capacity lowering mode of the up-shifting release side frictional element to be brought into the state is switched to engine starting, and in this mode, the transmission torque capacity of the upshifting release side shifting friction element is set to zero.

  According to the above-described engine start control device for a hybrid vehicle according to the present invention, when there is a mode switching request from the electric travel mode to the hybrid travel mode accompanying the engine start during the upshift of the automatic transmission, it is concluded at the time of the upshift. The side shift friction element is the second clutch, and its transmission torque capacity is made equal to the target drive torque target value at the time of engine start, and at the same time, the transmission torque capacity reduction mode of the release side shift friction element at the time of upshifting is switched to engine start. Since the transfer torque capacity of the release side shifting friction element at the time of upshifting is set to 0 in the aspect, the following effects are obtained.

  In other words, by setting the transmission torque capacity of the engagement-side shift friction element (second clutch) at the time of upshifting to a value equivalent to the target drive torque at the time of engine startup, the engine torque for reducing the transmission torque capacity of the release-side transmission friction element at the time of upshifting is used. The engine start process for switching the mode can be performed while realizing the target drive torque at the time of starting the engine in combination with the switching to the transmission, and at the same time, the transmission of the engagement side shifting friction element (second clutch) at the time of the upshift. The upshift of the automatic transmission can be continuously performed by the torque capacity control and the reduction of the transmission torque capacity of the disengagement side shift friction element during upshift to 0.

Therefore, according to the engine start control device of the present invention, when there is a mode switching request from the electric travel mode accompanying the engine start to the hybrid travel mode during the upshift of the automatic transmission, the mode switching is performed by the automatic transmission. This is performed in parallel with the upshift.
For this reason, the mode switching (engine start) is not greatly delayed with respect to the request timing, and there is no power shortage due to the response delay of the mode switching (engine start). Problems related to gender deterioration can be avoided.

  Further, according to the present invention, the upshift of the automatic transmission and the mode switching (engine start) are substantially simultaneously performed without any time lag, so that the former upshift is performed. The shock due to EV and the shock due to EV → HEV mode switching (engine start) can be taken as almost one shock, and it is preferable because the shock can be easily taken.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
[Constitution]
FIG. 1 shows a power train of a front engine / rear wheel drive hybrid vehicle having a hybrid drive device incorporating an engine start control device according to an embodiment of the present invention, together with its control system.
In FIG. 1, 1 is an engine as a power source, 2 is an automatic transmission, and 3 is a motor / generator as another power source.

  In the power train of the hybrid vehicle shown in FIG. 1, the automatic transmission 2 is arranged in tandem at the rear of the engine 1 in the vehicle longitudinal direction as in the case of a normal rear wheel drive vehicle, and the engine 1 (specifically, the crankshaft 1a) A motor / generator 3 is connected to a shaft 5 that transmits the rotation to the input shaft 4 of the automatic transmission 2.

The motor / generator 3 includes an annular stator 3a fixed in a housing and a rotor 3b arranged concentrically with a predetermined air gap in the stator 3a.
The motor / generator 3 functions as a motor (electric motor) or a generator (generator) according to a request for an operating state, and is disposed between the engine 1 and the automatic transmission 2.
The motor / generator 3 passes through the shaft 5 and is attached to the center of the rotor 3b, and uses the shaft 5 as a motor / generator shaft.

The first clutch 6 is inserted between the motor / generator 3 and the engine 1, more specifically, between the motor / generator shaft 5 and the engine crankshaft 1a, and the engine 1 and the motor / generator 3 are connected by the first clutch 6. Combine in a detachable manner.
Here, the first clutch 6 is assumed to be capable of continuously changing the transmission torque capacity. For example, the first clutch 6 is a wet type engine that can change the transmission torque capacity by continuously controlling the clutch hydraulic oil flow rate and the clutch hydraulic pressure with a proportional solenoid. It consists of a plate clutch.

The motor / generator 3 and the automatic transmission 2 are directly connected to each other by the direct connection of the motor / generator shaft 5 and the transmission input shaft 4.
The automatic transmission 2 is similar to the well-known planetary gear type automatic transmission in its transmission mechanism, but the torque converter is excluded from this, and the motor / generator 3 is directly connected to the transmission input shaft 4 instead. It shall be combined.

The automatic transmission 2 will be briefly described below.
The automatic transmission 2 includes an output shaft 7 arranged in a coaxial butt relationship with the input shaft 4.
A front planetary gear set Gf, a center planetary gear set Gm, and a rear planetary gear set Gr are sequentially placed on the input / output shafts 4 and 7 from the side of the engine 1 (motor / generator 3). The main component of the planetary gear transmission mechanism in FIG.

The front planetary gear set Gf closest to the engine 1 (motor / generator 3) 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 3) 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 3) includes a rear sun gear Sr, a rear ring gear Rr, a rear pinion Pr meshing with the rear sun gear Sr, and a rear planetary gear Cr that rotatably supports the rear pinion. Make a pair.

  Front brake 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 A brake R / B and a forward brake FWD / B are provided, and these are correlated with the above-described components of the planetary gear group Gf, Gm, Gr as follows to constitute a planetary gear transmission mechanism of the automatic transmission 2.

The front ring gear Rf is coupled to the input shaft 4, and the center ring gear Rm can be appropriately coupled to the input shaft 4 by the input clutch I / C.
The front sun gear Sf can be appropriately fixed to the transmission case 2a by the front brake Fr / B.
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 7, and the center sun gear Sm and the rear sun gear Sr can be coupled to each other by a high and low reverse clutch H & LR / C.

The rear sun gear Sr and the rear carrier Cr can be coupled by the direct clutch D / C, and the rear carrier Cr can be appropriately fixed to the transmission case 2a by the reverse brake R / B.
Further, the center sun gear Sm can be appropriately fixed to the transmission case 2a by the forward brake FWD / B.

  The power transmission train of the above planetary gear transmission mechanism is a selective transmission shown by the circles in Fig. 2 for six shift friction elements Fr / B, I / C, H & LR / C, D / C, R / B, and FWD / B. By the engagement, it is possible to obtain the forward shift speed and the reverse shift speed of the first forward speed, the second forward speed, the third forward speed, the fourth forward speed, and the fifth forward speed.

A hybrid vehicle having the power train of FIG. 1 composed of the engine 1, the motor / generator 3 and the automatic transmission 2 described above is provided between the motor / generator 3 and a drive wheel coupled to the transmission output shaft 7. A second clutch that is detachably coupled is required.
In this embodiment, the six clutch friction elements Fr / B, I / C, H & LR / C, D / C, R / B, and FWD / B existing in the automatic transmission 2 are used as the second clutch. Among them, the variable speed friction element that bears power transmission by fastening is used.
Incidentally, the existing transmission friction element in the automatic transmission 2 used as the second clutch is originally capable of continuously changing the transmission torque capacity like the first clutch 6 described above.

In the following, the function for each driving mode of the power train described above with reference to FIG. 1 will be described.
In the power train of FIG. 1, when the electric travel (EV) mode used at low load and low vehicle speed including when starting from a stopped state is required, the first clutch 6 is released and the second clutch (IC , H & LR / C, D / C, etc.) are put into the automatic transmission 2 in the power transmission state (shift stage selection state).

When the motor / generator 3 is driven in this state, only the output rotation from the motor / generator 3 reaches the transmission input shaft 4, and the automatic transmission 2 changes the rotation to the input shaft 4 to the selected shift. The speed is changed according to the speed and output from the transmission output shaft 7.
Then, the rotation from the transmission output shaft 4 reaches the left and right drive wheels through a differential gear device (not shown), and the vehicle can be electrically driven (EV traveling) only by the motor / generator 3. (EV mode)

When the hybrid running mode (HEV mode) used when running at high speeds, during heavy loads, or when the battery storage state SOC (carryable power) is low is required.
The first clutch 6 is engaged and the second transmission (IC, H & LR / C, D / C, etc.) is engaged to bring the automatic transmission 2 into a power transmission state (shift stage selection 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 3 reach the transmission input shaft 4, and the automatic transmission 2 is connected to the input shaft 4 Is rotated according to the currently selected shift speed and output from the transmission output shaft 7.
Thereafter, the rotation from the transmission output shaft 7 passes through a differential gear device (not shown) to reach the left and right drive wheels, and the vehicle can be hybrid-run by both the engine 1 and the motor / generator 3. (HEV mode)

In such HEV traveling, when the engine 1 is operated with the optimum fuel efficiency, when the energy becomes surplus, the surplus energy is converted into electric power by operating the motor / generator 3 as a generator with this surplus energy.
The fuel consumption of the engine 1 can be improved by storing the generated power to be used for driving the motor of the motor / generator 3.

A control system for the engine 1, the motor / generator 3, the first clutch 6, and the second clutch (IC, H & LR / C, D / C, etc.) in the transmission 2 is shown below. An outline will be described based on 1.
The control system includes an integrated controller 11 that integrally controls the operating point of the power train.
The operating points of the power train are the target engine torque tTe, the target motor / generator torque tTm, the target transmission torque capacity tTc1 of the first clutch 6, and the second clutch (IC, H & LR / C, D / C, etc.) It is defined by the target transmission torque capacity tTc2.

  The integrated controller 11 includes a signal from the engine rotation sensor 12 that detects the rotation speed Ne of the engine 1 and a motor / generator that detects the rotation speed Nm of the motor / generator 3 in order to determine the operating point of the power train. A signal from the rotation sensor 13, a signal from the input rotation sensor 14 for detecting the transmission input rotation speed Ni, and an output rotation sensor 15 for detecting the transmission output rotation speed No (from which the vehicle speed VSP can be calculated). Signal, signal from accelerator opening sensor 16 that detects accelerator pedal depression amount (accelerator opening APO), and battery state SOC of battery (not shown) that stores electric power for motor / generator 3 are detected. The signal from the storage state sensor 17 to be input is input.

  The integrated controller 11 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, and target engine torque tTe, target motor / generator torque tTm, first clutch target transmission torque capacity tTc1, and second clutch target transmission torque capacity tTc2 are calculated.

The target engine torque tTe is supplied to the engine controller 21.
The engine controller 21 uses the engine speed Ne detected by the sensor 12 and the target engine torque tTe to control the throttle opening and the fuel injection amount to achieve the target engine torque tTe based on the engine speed Ne. Thus, the engine 1 is controlled so that the engine torque becomes the target engine torque tTe.

The target motor / generator torque tTm is supplied to the motor / generator controller 22.
The motor / generator controller 22 converts the battery power into DC-AC with an inverter (not shown), and supplies it to the stator 3a of the motor / generator 3 under the control of the inverter. The motor / generator is controlled to match the motor / generator torque tTm.

  When the target motor / generator torque tTm is such that the motor / generator 3 requires a regenerative braking action, the motor / generator controller 22 is connected to the battery storage state SOC detected by the sensor 17 via the inverter. A power generation load is applied to the motor / generator 3 so that the battery is not overcharged, and the power generated by the motor / generator 3 due to the regenerative braking action is AC-DC converted to charge the battery.

The first clutch target transmission torque capacity tTc1 is supplied to the first clutch controller 23.
This first clutch controller 23 compares the first clutch engagement pressure command value corresponding to the first clutch target transmission torque capacity tTc1 with the actual engagement pressure of the first clutch 6 to determine the actual engagement pressure of the first clutch 6. Control is performed so that the engagement pressure of the first clutch 6 is controlled so as to be the first clutch engagement pressure command value, and the transmission torque capacity of the first clutch 3 becomes the target value tTc1.

The second clutch target transmission torque capacity tTc2 is supplied to the transmission controller 24.
The transmission controller 24 compares the second clutch engagement pressure command value corresponding to the second clutch target transmission torque capacity tTc2 with the actual engagement pressure of the second clutch (IC, H & LR / C, D / C, etc.). The engagement pressure of the second clutch (IC, H & LR / C, D / C, etc.) so that the actual engagement pressure Pc2 of the second clutch (IC, H & LR / C, D / C, etc.) becomes the second clutch engagement pressure command value To control the transmission torque capacity of the second clutch (IC, H & LR / C, D / C, etc.) to the target value tTc2.

  The transmission controller 24 basically sets the current driving state based on the planned shift map based on the transmission output rotation speed No (vehicle speed) detected by the sensor 15 and the accelerator opening APO detected by the sensor 16. A suitable gear position is obtained, and the transmission 2 is automatically shifted so that the suitable gear position is selected.

[Engine start control]
The above is the outline of the normal control executed by the control system of FIG. 1, but the engine start control will be described next.
In this embodiment, the engine when a request to switch to the hybrid travel (HEV) mode occurs due to depression of the accelerator pedal during travel in the electric travel (EV) mode with the first clutch 6 released. Suppose that the control system of FIG. 1 performs the start as follows according to the control program shown in FIG.

Accordingly, the control program of FIG. 3 is started when the above-described EV → HEV mode switching (engine start) request is generated.
First, in step S11 and step S12, it is checked whether or not the automatic transmission 2 has already been shifting (during downshifting or upshifting) when the EV → HEV mode switching (engine start) is requested.

  When it is determined in step S11 that the automatic transmission 2 has already been downshifted at the time of requesting EV → HEV mode switching (engine start), in step S13, the downshift is changed from the engaged state to the released state during the downshift. The following engine start shown in the time chart of Fig. 4 using the time-release-side shift friction element (if it is a 4 → 3 downshift, the input clutch I / C as shown in Fig. 2) is used as the second clutch. Execute control.

First, at the instant t1 when EV → HEV mode switching (engine start) is requested, the transmission torque capacity tTc2 of the release side shift friction element at the time of downshift as the second clutch is set to a value corresponding to the target drive torque at the time of engine start.
As a result, the second clutch (release-side shift friction element during downshift) slips, and the motor / generator rotational speed Nm increases as shown in the figure.

  The transmission torque capacity tTc1 of the first clutch 6 is changed to the first clutch 6 at an instant t2 at which the transmission torque capacity tTc2 of the second clutch (release side shifting friction element at the time of downshift) becomes a value corresponding to the target drive torque at the time of engine start. The motor / generator torque tTm is set so that the motor / generator speed Nm becomes the engine start target Nm by switching the motor / generator 3 from torque control to rotational speed control. Increase especially.

With the start of engagement of the first clutch 6 and the rotational speed control of the motor / generator 3, the engine 1 is cranked as is apparent from changes over time in the engine speed Ne and the engine torque tTe.
By this cranking, the engine 3 can be operated independently at the instant t3 (after engine start is completed), and the engine speed Ne matches the motor / generator speed Nm.
In order to fully engage the first clutch 6 at the instant t3, the transmission torque capacity tTc1 is maximized.

The transmission torque capacity tTc2 of the second clutch (release side shifting friction element at the time of downshift) is temporarily set to a value corresponding to the driving torque requested by the driver.
Then, at the instant t4 after the lapse of a predetermined time, the transmission torque capacity tTc2 of the second clutch (downshift release side shifting friction element) is increased to the maximum value, and the second clutch (downshift release side shifting friction element) is completely Let them conclude.

If it is determined in step S12 that the automatic transmission 2 has already been upshifted when EV → HEV mode switching (engine start) is requested, in step S14, the release state is changed to the engaged state during the upshift. Engine start as shown in the time chart of Fig. 5, using the shifting friction element at the time of upshifting (if it is a 4 → 5 upshift, the front brake Fr / B as shown in Fig. 2) is used as the second clutch. Start control.
Therefore, step S12 corresponds to the upshift detection means and the EV → HEV mode switching request detection means in the present invention.

Disengagement progress (transmission torque of the direct clutch D / C as is clear from FIG. 2 in the case of the upshift release side shifting friction element (4 → 5 upshift, which is changed from the engaged state to the released state during the upshift) EV → HEV mode switching during upshift (torque phase), which is performed by lowering the capacity tToff) and engaging progress of the engagement side shifting friction element (second clutch) during upshifting (increasing transmission torque capacity tTc2) At the instant t1 in FIG. 5 at which the (engine start) request has been made, first, in step S15, the transmission torque capacity tTc2 of the upshift engagement side shifting friction element (second clutch) is set to a value corresponding to the target drive torque at engine start. Eggplant.
Therefore, step S15 corresponds to the upshift engagement side shifting friction element control means in the present invention.

However, before the moment t2 ′ of FIG. 5 when the transmission torque capacity tToff of the release side shifting friction element at the time of upshifting becomes 0, the engagement side shifting friction element at the time of upshifting (second speed) according to the remaining amount of the transmission torque capacity tToff. Clutch) transmission torque capacity tTc2 is determined. During this time, the transmission torque capacity tTc2 is determined to be a difference value obtained by subtracting the transmission torque capacity tToff from the engine starting target drive torque.
Accordingly, it is possible to avoid the adverse effect that the transmission torque capacity tTc2 becomes too high and the automatic transmission 2 tends to be interlocked before the instant t2 ′ in FIG. 5 where the remaining amount of the transmission torque capacity tToff exists.

At the instant t1 when EV → HEV mode switching (engine start) is requested, in the same way, in step S15, the release side shift friction element at the time of upshift is gradually released (transmission torque capacity tToff is reduced). The speed of the element release progression (decrease in the transmission torque capacity tToff) is switched to the engine start speed θ1 that is faster than the upshift speed so far.
Thereby, from the EV → HEV mode switching (engine start) request instant t1 in FIG. 5, the transmission torque capacity tToff of the release side shift friction element at the time of upshift is rapidly reduced at a faster speed θ1 than before.
Accordingly, step S15 corresponds to the upshift release side shifting friction element control means in the present invention.

  The above-described control for setting the transmission torque capacity tTc2 of the engagement gear shifting friction element (second clutch) at the time of upshift to a value equivalent to the target drive torque at the time of starting the engine, and the transmission torque capacity tToff of the releasing speed transmission friction element at the time of upshift The second clutch (upshift side engagement frictional element) slips due to the control to decrease at the speed θ1, and the motor / generator rotational speed Nm is instantaneous when the upshift torque phase ends as shown in FIG. It rises temporarily just before t2.

Although not shown in the flowchart of FIG. 3, at the torque phase end instant t2, the transmission torque capacity tTc1 of the first clutch 6 is set to such a value that the first clutch 6 starts to be engaged, and the motor / generator 3 Is switched from torque control to rotational speed control, and the motor / generator torque tTm is controlled as shown in the figure so that the motor / generator rotational speed Nm becomes the engine start target Nm.
However, the engine start target Nm is set so that the value near the input rotation speed after the upshift is set to the lower limit value as shown in FIG. 5 and not lower than this, and finally the motor / generator rotation speed Nm is As shown in FIG. 5, the motor / generator torque tTm is controlled as shown in the figure (corresponding to the motor / generator control means) so as to be maintained at a value in the vicinity of the transmission input speed after the upshift.

By starting the engagement of the first clutch 6 described above from the torque phase end instant t2 and the rotation speed control of the motor / generator 3, the engine 1 is coupled as apparent from changes over time in the engine speed Ne and the engine torque tTe. Ranked.
As a result, the engine 3 can be operated independently at the instant t3 (after engine start is completed), and the engine speed Ne coincides with the motor / generator speed Nm.

The coincidence of the engine rotation speed Ne and the motor / generator rotation speed Nm described above means a rotation synchronization state where the front and rear rotations of the first clutch 6 are the same, and the rotation synchronization of the first clutch 6 is performed in step S16 of FIG. To check.
While it is determined in step S16 that the first clutch 6 has not yet been synchronized in rotation (the moment t3 in FIG. 5 has not been reached), the control is returned to step S15 to continue the engine start control and at the time of upshifting. Disengagement of disengagement side shift friction element (decrease in transmission torque capacity tToff) and increase by engagement of engagement side shift friction element (second clutch) during upshift (transmission torque capacity tTc2 = target drive torque equivalent value at engine start) Let the shift continue.

In order to fully engage the first clutch 6 at the first clutch rotation synchronization instant t3 of FIG. 5 where it is determined that the rotation of the first clutch 6 is synchronized in step S16, the transmission torque capacity tTc1 is set to the maximum value.
At the same time, the control proceeds to step S17 where the transmission torque capacity tTc2 of the second clutch (upshift engagement frictional shift element) is once increased to a value corresponding to the driving torque required by the driver and during the upshift. The transmission torque capacity tToff of the disengagement side shift friction element is set to a value corresponding to complete disengagement.

  Transfer torque capacity control (tTc2 = driver-requested drive torque) of the second clutch (upshift engagement side shifting friction element) in step S17 and transmission torque capacity control (tToff = complete release) of the release side transmission friction element during upshifting When the upshift end-of-shift process proceeds according to the equivalent value), the second clutch (upshift engagement-side shift friction element) is in a rotation-synchronized state with no front-rear rotation difference, and the shift ends.

The rotation synchronization (shift completion) applied by the second clutch (engagement side shifting friction element during upshift) is checked in step S18, and the second clutch (engagement side transmission friction element during upshifting) is synchronized in rotation at the instant t4 in FIG. Previously, the control is returned to step S17, and the upshift end-of-shift process is further advanced.
When it is determined in step S18 that the second clutch (engagement-side shift friction element at the time of upshifting) is synchronized in rotation, the shift end instant t4 in FIG. 5 is reached, control proceeds from step S18 to step S19, and the second clutch (up The transmission torque capacity tTc2 of the shift-side engagement friction element during shifting is set to the maximum control value, and the transmission torque capacity tToff of the release-side transmission friction element during upshifting is set to 0 to prepare for the next shift.

  When it is determined in step S11 and step S12 that the EV → HEV mode switching (engine start) request is not for gear shifting, in step S21, EV → HEV mode switching (engine start) is determined from the accelerator opening APO and the vehicle speed VSP. ) Estimate the degree of acceleration of the vehicle during the process, and predict the upshift depending on whether there is a change in the vehicle speed that causes an upshift during the EV → HEV mode switching (engine start) process.

If “no upshift prediction” is determined in step S21, it is determined in step S22 whether or not a set time has elapsed since the EV → HEV mode switching (engine start) request.
While it is determined in step S22 that the set time has not elapsed since the EV → HEV mode switching (engine start) request, in step S23, the downshift release-side shift friction element is used as the second clutch. The engine start control shown in FIG. 6 is executed, and thereby EV → HEV mode switching (engine start) is advanced without delay.

  After execution of step S23, the control is returned to step S21. When it is determined in step S22 that the set time has elapsed from the EV → HEV mode switching (engine start) request, in step S24, the downshift release side shifting friction element is selected. The engine start control shown in FIG. 4 used as the second clutch is executed, whereby EV → HEV mode switching (engine start) is further advanced.

Steps S23 and S24 are similar, but the processing is performed in step S23 before it is determined in step S22 that the set time has elapsed from the EV → HEV mode switching (engine start) request, and EV in step S22. → After determining that the set time has elapsed since the HEV mode switching (engine start) request, the reason for carrying out the process in step S24 is that the down-shifting side shifting friction element during the downshift This is to make it possible to change the shift friction element used as the two-clutch.
Accordingly, the set time in step S22 is a time obtained by adding a margin to the time until the release-side shift friction element at the time of downshift starts slipping.

  The shift friction element that became the second clutch due to the above change is released for slipping, and the shift friction element that is no longer the second clutch due to the above change is engaged at a predetermined time change rate to prevent shock. Let

  If it is determined in step S21 that “upshift prediction is present”, in step S25, the upshift release side frictional element (from 4 to 5 upshifts) that is changed from the engaged state to the released state during the upshift. As is apparent from FIG. 2, engine start control as shown in the time chart of FIG. 6 is executed using the direct clutch D / C) as the second clutch.

Figure 6 shows the case where an EV → HEV mode switching (engine start) request occurs at the instant t1 due to the depression of the accelerator pedal that increases the accelerator opening APO as shown in the figure, and then an upshift is predicted It is an operation time chart.
First, at the engine start request instant t1, the transmission torque capacity tTc2 of the upshift disengagement side shift friction element as the second clutch is set to a value corresponding to the engine start target drive torque.
As a result, the second clutch (release-side shift friction element during upshifting) slips, and the motor / generator rotational speed Nm increases as shown in the figure.

  The transmission torque capacity tTc1 of the first clutch 6 is changed to the first clutch 6 at an instant t2 when the transmission torque capacity tTc2 of the second clutch (release-side shift friction element at the time of upshift) becomes a value corresponding to the target drive torque at the time of engine start. The motor / generator torque tTm is set so that the motor / generator speed Nm becomes the engine start target Nm by switching the motor / generator 3 from torque control to rotational speed control. Increase especially.

With the start of engagement of the first clutch 6 and the rotational speed control of the motor / generator 3, the engine 1 is cranked as is apparent from changes over time in the engine speed Ne and the engine torque tTe.
With this cranking, the engine 3 can be operated independently at an instant t3 (after engine start is completed), and the engine speed Ne matches the motor / generator speed Nm.
In order to fully engage the first clutch 6 at this instant t3, the transmission torque capacity tTc1 is set to the maximum value,
Decrease the transmission torque capacity tTc2 of the second clutch (release-side shift friction element during upshift).

At the instant t4 immediately before the transmission torque capacity tTc2 becomes zero due to the decrease in the transmission torque capacity tTc2, the second clutch (upshift release side shifting friction element) is completely released.
On the other hand, the transmission torque capacity tToff of the release side shift friction element at the time of downshift is kept at the value when the upshift prediction is made in step S21.
For this reason, the engagement progress of the upshift engagement friction element (not shown in FIG. 6), which is engaged in response to the upshift request, and the second clutch (the upshift release friction element) The upshift can be carried out by releasing.

[Effect]
By the way, according to the present embodiment, when the automatic transmission 2 is upshifted (step S12), when there is a mode switching request from the electric travel (EV) mode with the engine start to the hybrid travel (HEV) mode (see FIG. 5 at the moment t1), the engagement side shifting friction element at the time of upshift is set as the second clutch (step S14), and the transmission torque capacity tTc2 is not equivalent to the target driving torque at the time of engine start as shown in FIG. 5 (step S15). At the same time, the transmission torque capacity (tToff) of the disengagement side shift friction element at the time of upshifting is reduced for engine start where the speed of decrease of the transmission torque capacity tToff is faster than the speed during the upshift before the instant t1 as shown in FIG. The speed is reduced so that the transmission torque capacity tToff of the disengagement side shifting friction element during upshifting is reduced to 0 at this reduction speed θ1 for starting the engine. (Step S15), the following effects are obtained.

  In other words, when an EV → HEV mode switching (engine start) request is made during an upshift (momentary t1 in Fig. 5), the transmission torque capacity tTc2 of the engagement side shifting friction element (second clutch) during the upshift is By setting the target drive torque equivalent value, the transmission torque capacity (tToff) decrease speed of the release-side shift friction element at the time of upshifting is switched from the upshift speed to the rapid engine start speed θ1, at the time of engine start While realizing the target drive torque, the engine start process for EV → HEV mode switching can be performed, and at the same time, the transmission torque capacity (tTc2) control of the engagement gear shift friction element (second clutch) during upshift and When the transmission torque (tToff) capacity of the disengagement side shifting friction element during upshifting is suddenly reduced to 0, the automatic transmission 2 can be continuously upshifted. That.

Therefore, according to the engine start control of this embodiment, when there is a request for EV → HEV mode switching (engine start) during the upshift of the automatic transmission 2, the mode switching (engine start) is It will be performed in parallel with the upshift.
For this reason, the mode switching (engine start) is not greatly delayed with respect to the request timing, and there is no power shortage due to the response delay of the mode switching (engine start). Problems related to gender deterioration can be avoided.

  In addition, according to the present embodiment, the upshift of the automatic transmission 2 and the EV → HEV mode switching (engine start) are performed substantially at the same time without any time lag. The shock due to the upshift and the shock due to EV → HEV mode switching (engine start) can be taken as almost one shock, and the shock can be easily taken.

  Furthermore, in this embodiment, when there is a request for EV → HEV mode switching (engine start) during upshifting (instantaneous t1 in FIG. 5), the transmission torque capacity (tToff) lowering mode of the upshifting release side frictional element is changed, When switching from upshift to engine start, the transmission torque capacity (tToff) lowering speed of the upshift disengagement side frictional element is switched from the upshift speed to the sudden engine start speed θ1. The effect is obtained.

  In other words, the upshift engagement side shift friction element (second shift) that is generated for engine start by setting the transmission torque capacity tTc2 of the upshift engagement side shift friction element (second clutch) to a value equivalent to the target drive torque at engine start. (2 clutch) slip start can be accelerated by switching from the upshift speed to the sudden engine start speed θ1 from the upshift speed at which the transmission torque capacity (tToff) decrease of the up-shift release friction element is changed. The start response can be made high in response to the driver's accelerator operation.

  As shown in FIG. 5, the engine start target Nm is set so that the value near the input rotation speed after the upshift is set to the lower limit value and not lower than this, and finally the motor / generator rotation speed Nm is As shown in FIG. 5, since the motor / generator 3 is controlled so as to maintain a value in the vicinity of the transmission input speed after the upshift, the engine speed Ne rises at the start and coincides with the motor / generator speed Nm. Thus, the rotation synchronization instant t3 (see FIG. 5) of the first clutch 6 can be advanced, and as a result, the upshift response of the automatic transmission 2 can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a power train of a front engine / rear wheel drive hybrid vehicle including a hybrid drive device incorporating an engine start control device according to an embodiment of the present invention, together with its control system. FIG. 2 is an engagement logic diagram showing a relationship between a selected shift stage of the automatic transmission in FIG. 1 and a combination of engagement of shift friction elements. 2 is a flowchart showing an engine start control program executed by a power train control system in FIG. FIG. 4 is an operation time chart of engine start control during downshifting executed by the engine start control program of FIG. 3. FIG. FIG. 4 is an operation time chart of engine start control during upshift executed by the engine start control program of FIG. 3. FIG. FIG. 4 is an operation time chart illustrating engine start control executed when the engine start control program of FIG. 3 executes and an upshift is predicted after an engine start request.

Explanation of symbols

1 Engine (Power source)
2 Automatic transmission 3 Motor / generator (power source)
4 Transmission input shaft 6 First clutch 7 Transmission output shaft
I / C input clutch (shifting friction element)
H & LR / C high and low reverse clutch
D / C direct clutch (shifting friction element)
11 Integrated controller
12 Engine rotation sensor
13 Motor / generator rotation sensor
14 Transmission input rotation sensor
15 Transmission output rotation sensor
16 Accelerator position sensor
17 Storage state sensor
21 Engine controller
22 Motor / generator controller
23 1st clutch controller
24 Transmission controller

Claims (3)

With engine and motor as power source,
A first clutch is interposed between the engine and the motor, and a second clutch is interposed between the motor and the drive wheel. The second clutch is responsible for power transmission in the automatic transmission inserted between the motor and the drive wheel. Diverting the variable speed friction element
By 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. By engaging both the first and second clutches, the power from both the engine and the motor can be selected. Hybrid driving mode can be selected,
In the hybrid vehicle capable of switching the mode to the hybrid driving mode by starting the engine with the power from the motor by making the first clutch engage and advance while slipping the second clutch while the electric driving mode is selected.
Upshift detecting means for detecting that the automatic transmission is upshifting;
Upshift EV → HEV mode switching request detection for detecting that there is a mode switching request from the electric traveling mode to the hybrid traveling mode with the engine start while the upshift is detected by the means Means,
When the request for switching from the electric travel mode during the upshift to the hybrid travel mode is detected by the means, the upshift engagement frictional friction element that is changed from the released state to the engaged state at the time of the upshift is the second clutch. Up-shift engagement side frictional friction element control means for setting the transmission torque capacity of the friction element to a value equivalent to the target drive torque at engine start;
When the transmission torque capacity control of the engagement side shifting friction element at the time of upshift by the means is performed, the engine is started in the transmission torque capacity lowering mode of the upshifting release side transmission friction element that is changed from the engagement state to the release state at the time of the upshift of the automatic transmission. Engine start control of a hybrid vehicle, characterized in that it comprises an upshift release-side shift friction element control means for making the transmission torque capacity of the upshift release-side shift friction element to 0 in this manner. apparatus. In the engine start control device of the hybrid vehicle according to claim 1,
The upshift release-side transmission friction element control means increases the transmission torque capacity reduction rate of the upshift release-side transmission friction element when switching the transmission torque capacity reduction mode of the up-shift release-side transmission friction element to engine start. What is claimed is: 1. An engine start control device for a hybrid vehicle. In the engine start control device of the hybrid vehicle according to claim 1 or 2,
Motor control means is provided for controlling the rotational speed of the motor so that a target transmission input side rotational speed set to a value in the vicinity of the transmission input side rotational speed after the upshift is realized during the engine start. An engine start control device for a hybrid vehicle.

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