JP2008074254A - Descending road travel controller for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a failure of regeneration braking by a motor/generator due to release of a clutch during travel on a descending road while capacity control for equalizing an output side number of revolutions of the clutch with a target value is carried out. <P>SOLUTION: From t1, an input side number Ni of revolutions of the clutch is increased by starting output of motor torque Tm. From t2, the clutch is started to be engaged, and travel is started by increasing an output side number No of revolutions of the clutch. From t3, torque capacity Tc2 is controlled for equalizing the output side number No of revolutions with a target value tNo. After t4, transition to descending road travel is carried out and the number No of revolutions is increased, and consequently, transmission torque capacity Tc2 becomes zero by slip control of the clutch, and the clutch is released. Therefore, the output side number No of revolutions of the clutch is increased because of travel on the descending road, and after t5 at which the number of revolutions becomes a value within a predetermined deviation to the input side number Ni of revolutions of the clutch, that is, after determination of descending road travel, FLAG=2 is attained and engagement of the clutch is instructed. Regeneration braking by the motor is allowed by engagement of the clutch and the output side number No of revolutions (a vehicle velocity) of the clutch can be prevented from increasing. <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 downhill traveling control device for a hybrid vehicle having a hybrid traveling (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, instead of the torque converter, the motor / generator and the transmission output shaft are detachably coupled to each other.

When the hybrid vehicle having such a hybrid drive device disengages 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, and the first clutch and the second clutch When both the clutches are engaged, a hybrid running (HEV) mode that can run with power from both the engine and the motor / generator can be set.
Japanese Patent Laid-Open No. 11-082260

By the way, in the hybrid vehicle described above, the second clutch may be slip-controlled so that the driving wheel side rotation speed of the second clutch becomes, for example, a target value obtained from a target value of transmission torque capacity of the second clutch. .
During slip control of the second clutch, when the vehicle is about to go downhill, the drive wheel side rotation speed of the second clutch tends to increase due to an increase in drive wheel rotation speed due to the downhill road. It is in.

Therefore, the driving wheel side rotation speed of the second clutch tends to exceed the target value, and in order to prevent this, in the slip control of the second clutch, the second clutch is configured so that the power from the power source toward the driving wheel is reduced. The transmission torque capacity (fastening force) is reduced.
When the downhill travel continues for a long time or when the downhill road travels abruptly, the second clutch finally reaches the transmission torque capacity (fastening force), and the second clutch is released.

  The disengaged state of the second clutch is that the driving wheel is disconnected from the motor / generator and the engine and the driving wheel rotation speed increases even when the accelerator pedal is released, but the engine brake cannot be used. Insufficient deceleration or regenerative braking by the motor / generator cannot be performed, leading to a decrease in energy efficiency.

The above problem will be supplemented by FIG.
This FIG. 13 increases the input side (motor / generator side) rotational speed Ni of the second clutch as shown in the figure by starting the output of the motor / generator torque Tm from the instant t1.
From the instant t2, the second clutch starts to be engaged by increasing the transmission torque capacity Tc2, and the vehicle starts to travel by increasing the output side (drive wheel side) rotational speed No of the second clutch.
From the instant t3, the second clutch slip control is performed to control the transmission torque capacity Tc2 of the second clutch so that the output side rotational speed No matches the target value (see the second clutch slip control flag),
After the instant t4, as the result of the transition from flat road running to downhill road running and the output side rotational speed No increasing, the transmission torque capacity Tc2 becomes 0 by the slip control of the second clutch, and the second clutch is released. It is an operation | movement time chart when said slip control is complete | finished.

The second clutch remains in the disengaged state after the second clutch is released and the slip control for maintaining the output side rotational speed No at the target value is completed, and the drive wheel remains disconnected from the motor / generator and the engine. Therefore, the output side rotational speed No of the second clutch gradually increases as shown in the figure as the driving wheel rotates and rises due to traveling downhill,
The output side rotational speed No of the second clutch further increases as shown in the figure after the instant t5 when it coincides with the input side rotational speed Ni.
In other words, after the instant t4, even if the accelerator pedal is released, the vehicle is traveling on a downhill road where the rotational speed of the drive wheel increases as described above, but engine braking cannot be used, causing insufficient deceleration, or regeneration by the motor / generator. Inability to perform braking results in a decrease in energy efficiency.

  The present invention is based on the fact that the above problem is caused by the release of the second clutch while traveling downhill, and the second clutch is engaged during downhill traveling or the slip control is enabled. Another object of the present invention is to propose a downhill traveling control device for a hybrid vehicle that solves the above-described problems by coupling a power source and driving wheels.

For this purpose, the downhill traveling control device for a hybrid vehicle according to the present invention is:
An engine and a motor / generator are provided as the power source, and a first clutch capable of changing the transmission torque capacity is interposed between the engine and the motor / generator to transmit to a wheel drive system including a transmission from the motor / generator to the drive wheels. Insert the second clutch that can change the torque capacity,
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, and by engaging both the first and second clutches, the engine Assuming a hybrid vehicle that can select the hybrid driving mode with power from both the motor and generator,
The present invention is configured as described in claim 1 or 2.

A downhill traveling control device according to the present invention according to claim 1, in the hybrid vehicle,
While the second clutch is slip-controlled so that the driving wheel side rotation speed of the second clutch becomes a target value, the driving wheel side rotation speed of the second clutch is also released after the second clutch is released. Rises to a rotational speed within a predetermined deviation from the rotational speed on the motor / generator side of the second clutch.
The second clutch is engaged, and the wheel drive system between the second clutch and the drive wheels is configured to be regeneratively braked by a motor / generator.

Further, the downhill traveling control device according to the present invention as claimed in claim 2, in the hybrid vehicle,
While the second clutch is slip-controlled so that the driving wheel side rotation speed of the second clutch becomes a target value, the driving wheel side rotation speed of the second clutch is also released after the second clutch is released. Rises to a rotational speed within a predetermined deviation from the rotational speed on the motor / generator side of the second clutch.
The motor / generator side rotation speed of the second clutch is made less than the driving wheel side rotation speed by the output control of the power source, and the slip control of the released second clutch is resumed. Is.

According to the downhill traveling control apparatus according to the present invention as set forth in claim 1, during the slip control of the second clutch, the driving wheel side rotational speed increases even after the second clutch is released, and the second clutch When the rotational speed within the predetermined deviation with respect to the rotational speed on the motor / generator side of the clutch is engaged, the second clutch is engaged and the wheel drive system between the second clutch and the driving wheel is regeneratively braked by the motor / generator.
During the slip control of the second clutch, when the rotational speed on the drive wheel side of the second clutch increases due to traveling on a downhill road despite the second clutch being released, the wheel between the second clutch and the drive wheel The drive system can be regeneratively braked by at least a motor / generator, and there is no shortage of deceleration during downhill travel, and energy efficiency can be improved by energy recovery by regenerative braking.

According to the downhill traveling control device according to the present invention described in claim 2,
During the slip control of the second clutch, even after the second clutch is released, the rotational speed on the drive wheel side increases to a rotational speed within a predetermined deviation from the motor / generator side rotational speed of the second clutch. When the motor / generator side rotational speed of the second clutch is less than the driving wheel side rotational speed by the output control of the power source, the slip control of the released second clutch is resumed.
During the slip control of the second clutch, when the driving wheel side rotation speed of the second clutch rises despite the second clutch being released due to traveling on the downhill road, By restarting the slip control of the two clutches, the wheel drive system between the second clutch and the drive wheels is connected to at least the motor / generator, and the wheel drive system can be regeneratively braked by the motor / generator. There is no shortage of deceleration during running on a slope, and energy efficiency can be improved by energy recovery by regenerative braking.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a wheel drive system (power train) of a hybrid vehicle equipped with a downhill traveling control device of the present invention, together with its control system,
1 is a motor / generator as a first power source, 2 is an engine as a second power source, and 3L and 3R are left and right drive wheels (left and right rear wheels), respectively.

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

The motor / generator 1 is an AC synchronous motor, which acts as a motor when driving the wheels 3L and 3R, and acts as a generator (generator) when regeneratively braking the wheels 3L and 3R. Place between 4 machines.
The first clutch 6 can be inserted between the motor / generator 1 and the engine 2, more specifically, between the shaft 5 and the engine crankshaft 2a, and the engine 2 and the motor / generator 1 can be disconnected by the first clutch 6. To join.
Here, the first clutch 6 is a dry clutch whose transmission torque capacity can be changed continuously or stepwise. For example, the transmission torque capacity can be changed by continuously controlling the clutch fastening force with an electromagnetic solenoid. .

A second clutch 7 is inserted between the motor / generator 1 and the automatic transmission 4, more specifically between the shaft 5 and the transmission input shaft 4a, and the motor / generator 1 and the automatic transmission 4 are inserted by the second clutch 7. The releasable connection is made.
Similarly to the first clutch 6, the second clutch 7 can change the transmission torque capacity continuously or stepwise. For example, the second clutch 7 is a proportional solenoid and the clutch hydraulic oil flow rate and the clutch hydraulic pressure are continuously changed. And a wet multi-plate clutch capable of changing the transmission torque capacity by controlling automatically.

The automatic transmission 4 is the same as that described on pages C-9 to C-22 of the "Skyline New Car (CV35) Manual" published 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 system path (shift stage) is determined by a combination of engagement and release of these shift friction elements.
Accordingly, the automatic transmission 4 shifts the rotation from the input shaft 4a with a gear ratio corresponding to the selected shift speed, and outputs it to the output shaft 4b.
This output rotation is distributed and transmitted to the left and right rear wheels 3L and 3R by a final reduction gear 8 including a differential gear device, and is used for traveling of the vehicle.
However, it goes without saying that the automatic transmission 4 is not limited to the stepped type as described above, and may be a continuously variable transmission.

In the hybrid vehicle power train shown in FIG. 1 described above, the first clutch 6 is disengaged when the electric travel (EV) mode used at the time of low load and low vehicle speed including when starting from a stopped state is required. Then, the second clutch 7 is engaged, and the automatic transmission 4 is brought into a power transmission state.
When the motor / generator 1 is driven in this state, only the output rotation from the motor / generator 1 reaches the transmission input shaft 4a, and the automatic transmission 4 changes the rotation to the input shaft 4a to the selected shift speed. The speed is changed according to the speed and output from the transmission output shaft 4b.
The rotation from the transmission output shaft 4b then reaches the left and right rear wheels 3L, 3R via the final reduction gear 8 including the differential gear device, and the vehicle can be electrically driven (EV traveling) only by the motor / generator 1.

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 4 is brought into a power transmission state.
In this state, the output rotation from the engine 2 or both the output rotation from the engine 2 and the output rotation from the motor / generator 1 reach the transmission input shaft 4a, and the automatic transmission 4 is connected to the input shaft 4a. Is rotated according to the selected gear position and output from the transmission output shaft 4b.
Then, the rotation from the transmission output shaft 4b reaches the left and right rear wheels 3L and 3R via the final reduction gear 8, and the vehicle can be hybrid-driven (HEV travel) by both the engine 2 and the motor / generator 1.

  In such HEV traveling, if the engine 2 is operated with the optimum fuel efficiency and the energy becomes surplus, the surplus energy is converted into electric power by operating the motor / generator 1 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 1, the fuel efficiency of the engine 2 can be improved.

  In FIG. 1, the second clutch 7 for releasably connecting the motor / generator 1 and the drive wheels 3L, 3R is interposed between the motor / generator 1 and the automatic transmission 4, but the automatic transmission 4 and the final deceleration are also provided. It may be interposed between the machines 8, or a shift friction element for selecting a gear position in the automatic transmission 4 may be used.

FIG. 1 further shows a control system for the engine 2, the motor / generator 1, the first clutch 6, the second clutch 7, and the automatic transmission 4 that constitute the power train of the hybrid vehicle described above.
The control system of FIG. 1 includes an integrated controller 20 that performs integrated control of the operating point of the power train. The operating point of the power train is set to an engine torque target value tTe and a motor / generator torque target value tTm (motor / generator rotation speed target). Value tNm), the target torque capacity value tTc1 of the first clutch 6, the target torque capacity tTc2 of the second clutch 7 (may be a clutch hydraulic solenoid current), and the target gear stage Gm of the automatic transmission 4. Stipulated in

  In order to determine the operating point of the power train, the integrated controller 20 receives a signal from the accelerator opening sensor 11 that detects the accelerator opening APO and a signal from the vehicle speed sensor 12 that detects the vehicle speed VSP. .

Here, the motor / generator 1 is driven and controlled via the inverter 22 by the electric power from the battery 21, but as long as the motor / generator 1 acts as a generator as described above, the generated electric power is stored in the battery 21. Shall be kept.
At this time, the battery 21 is controlled to be charged by the battery controller 23 so that the battery 21 is not overcharged.
For this reason, the battery controller 23 detects the storage state SOC (carryable power) of the battery 21 and supplies information related to this to the integrated controller 20.

The integrated controller 20 selects an operation mode (EV mode, HEV mode) capable of realizing the driving force of the vehicle desired by the driver from the accelerator opening APO, the battery storage state SOC, and the vehicle speed VSP, and the engine. Torque target value tTe, motor / generator torque target value tTm, first clutch transmission torque capacity target value tTc1, second clutch transmission torque capacity target value tTc2, and target gear stage Gm of automatic transmission 4 are calculated.
The engine torque target value tTe is supplied to the engine controller 24, and the motor / generator torque target value tTm is supplied to the motor / generator controller 25.

The engine controller 24 controls the engine 2 so that the engine torque Te becomes the engine torque target value tTe,
The motor / generator controller 25 controls the motor / generator 1 via the inverter 22 with the electric power from the battery 21 so that the torque Tm of the motor / generator 1 becomes the motor / generator torque target value tTm.

The integrated controller 20 supplies the first clutch transmission torque capacity target value tTc1 and the second clutch transmission torque capacity target value tTc2 to the clutch controller 26, respectively.
On the other hand, the clutch controller 26 supplies a solenoid current corresponding to the first clutch transmission torque capacity target value tTc1 to an electromagnetic force control solenoid (not shown) of the first clutch 6, and the transmission torque capacity Tc1 of the first clutch 6 is The first clutch 6 is controlled to be engaged so as to coincide with the transmission torque capacity target value tTc1.
On the other hand, the clutch controller 26 supplies a solenoid current corresponding to the second clutch transmission torque capacity target value tTc2 to the hydraulic control solenoid of the second clutch 7, and the transmission torque capacity Tc2 of the second clutch 7 is the second clutch transmission torque capacity. The second clutch 7 is controlled to be engaged so as to match the target value tTc2.

  The target gear stage Gm determined by the integrated controller 20 is input to the transmission controller 27, and the transmission controller 27 controls the automatic transmission 4 so that the target gear stage (target gear ratio) tTm is selected.

In this embodiment, the integrated controller 20 controls the engagement of the second clutch 7 via the clutch controller 26 so as to meet the object of the present invention, and the motor / generator 1 via the motor / generator controller 25 of the present invention. It is assumed that the drive is controlled to meet the purpose.
For the engagement control of the former second clutch 7, the clutch input side rotational speed sensor 13 for detecting the rotational speed of the motor / generator 1 as the input side rotational speed Ni of the second clutch 7, and the output of the second clutch 7 A clutch output side rotational speed sensor 14 for detecting the rotational speed of the transmission input shaft 4a is provided as the side rotational speed No, and signals from these rotational sensors 13 and 14 are input to the integrated controller 20 via the clutch controller 26.

The integrated controller 20 executes the control program of FIGS. 2 and 3 to control the engagement of the second clutch 7 as intended by the present invention, and the motor / generator 1 as intended by the present invention. Drive control is performed to perform predetermined downhill traveling control targeted by the present invention.
The control program in FIG. 2 is a main routine that is repeatedly executed by a scheduled interrupt in EV mode.
First, in step S1, data from each of the controllers 23 to 27 is received, and the battery storage state SOC, the input side rotational speed Ni and the output side rotational speed No of the second clutch 7, and the automatic transmission selected shift stage (selection) Gear ratio) Gm is read.

In the next step S2, the accelerator opening APO and the vehicle speed VSP are read based on signals from the sensors 11 and 12.
In the next step S3, for example, the wheel drive torque target value tTd is obtained by searching from the vehicle speed VSP and the accelerator opening APO based on the planned drive force map shown in FIG.
Thereafter, in step S4, a motor torque target value tTm and an engine torque target value tTe for determining how to share the wheel drive torque target value tTd between the motor / generator 1 and the engine 2 are obtained.
The latter engine torque target value tTe is directly output to the corresponding engine controller 24 in step S18.
The former motor torque target value tTm is corrected for downhill traveling in the next step S5 to be a downhill road traveling motor torque target value (indicated by the same symbol tTm), and then the corresponding motor / generator in step S18. Output to controller 25.

The correction for traveling downhill with respect to the motor torque target value tTm performed in step S5 is executed as shown in FIG.
In step S21, it is checked whether the vehicle is traveling on a downhill road. In this check, for example, the transmission torque capacity target value tTc2 of the second clutch 7 is 0 (the second clutch 7 is released), and the driving force is not transmitted from the power source to the output side of the second clutch 7. When the output side rotational speed No of the second clutch 7 increases and becomes a rotational speed within a predetermined deviation with respect to the input side rotational speed Ni of the second clutch (the difference in input / output side rotational speed of the second clutch 7, that is, When the slip amount is less than a predetermined value), it is determined that the vehicle is traveling on a downhill road.

In the next step S22, the motor rotational speed target value tNm (input side rotational speed target value of the second clutch 7) of the motor / generator 1 is obtained by calculation of the following equation.
First, based on the drive torque target value tTd obtained in step S3, the vehicle running resistance Tr on a flat road obtained beforehand (however, this flat road running resistance Tr is a value converted to the output side of the second clutch 7). The output side drive torque target value tTo of the second clutch 7 is obtained by the calculation of the following equation,
tTo = tTd−Tr (1)
Next, the second clutch output side drive torque target value tTo, the vehicle inertia moment Jo, the speed ratio Gm determined by the selected gear stage of the automatic transmission 4 in the wheel drive system, and the final speed of the final reduction gear 8 in the wheel drive system Based on the reduction ratio Gf, the motor speed target value tNm of motor / generator 1 is
tNm / tTo = {(Gm · Gf) ² / Jo} × (1 / s) (2)
Calculated by

In the next step S23, the motor rotational speed reference value Nmref for matching with the reference model is calculated through the motor rotational speed target value tNm through the reference model Gmref (s) of the motor / generator 1.
In calculating the motor rotation speed reference value Nmref, the calculation is actually performed using the following recurrence formula obtained by discretization by Tustin approximation or the like.
(Nmref / tNm) ＝ Gmref (s)
= 1 / (τ _mref · s + 1) (3)
However, τ _mref : Standard response time constant for motor / generator control

In the next step S24, the motor rotational speed deviation Nmerr (= Nmref−Nm) between the motor rotational speed reference value Nmref and the motor rotational speed detection value Nm of the motor / generator 1 is set to 0, and the motor rotational speed is set. A motor torque correction amount ΔTmfb for feedback control necessary to make the motor rotation speed detection value Nm coincide with the reference value Nmref is calculated.
In calculating the motor torque correction amount ΔTmfb, the calculation is actually performed using the following recurrence formula obtained by discretization by Tustin approximation or the like.
ΔTmfb = {Kmp + (Kmi / s)} · Nmerr (4)
Kmp: Proportional control gain
Kmi: Integral control gain

In the next step S25, the motor torque target value tTm obtained in step S4 as described above is corrected by the motor torque correction amount ΔTmfb (tTm + ΔTmfb), and the motor torque target value when traveling on a downhill road (indicated by the same symbol tTm). This is output to the corresponding motor / generator controller 25 in step S18 of FIG.
If it is determined in step S21 in FIG. 3 that the vehicle is not traveling on a downhill road, the control proceeds to step S26, and the integrator used when obtaining the motor torque feedback correction amount ΔTmfb as described above in steps S22 to S24 is initialized. This prevents accumulation of calculation errors and the like in this integrator.

After obtaining the motor torque target value tTm when traveling downhill as described above in FIG. 3, the control returns to step S6 in FIG. 2, where the output side rotational speed No. of the second clutch 7 is the target. It is checked whether or not the engagement control (output side rotation speed control) should be performed so as to match the value.
In this check, for example, the slip amount of the second clutch 7 which is the rotation difference between the input side rotational speed Ni and the output side rotational speed No of the second clutch 7 is set to a set value (determination of downhill traveling in step S21 in FIG. 3). Is equal to or greater than the predetermined slip amount used when performing the engagement), it is determined that the engagement control based on the output side rotational speed No of the second clutch 7 should be performed, and the slip amount of the second clutch 7 becomes less than the set value. Then, it is determined that the engagement control of the second clutch 7 should not be performed.

  When it is determined in step S6 that the engagement control based on the output side rotational speed No of the second clutch 7 should be performed, in step S7, the second clutch 7 according to the driving operation of the vehicle by the driver or the traveling state of the vehicle is determined. The basic transfer torque capacity target value tTclbase is calculated.

The basic clutch transmission torque capacity target value tTclbase may be set to the same value as the wheel drive torque target value tTd obtained from the accelerator opening APO and the vehicle speed VSP in step S3, for example, but can also be obtained as follows.
In other words, from the speed ratio E (= No / Ni) represented by the ratio of the output side rotational speed No to the input side rotational speed Ni of the second clutch 7, the second clutch 7 of the second clutch 7 is based on the torque converter characteristics illustrated in FIG. The basic clutch transmission torque capacity target value tTclbase may be obtained by obtaining the transmission torque capacity coefficient Ccl and calculating the following equation using this and the input side rotational speed Ni of the second clutch 7.
tTclbase ＝ Ccl × Ni ²・ ・ ・ （5）

Steps S8 to S17 in the frame surrounded by a broken line in FIG. 2 correspond to the transmission torque capacity control based on the output side rotational speed of the second clutch 7 which is the premise of the gist of the present invention. This is as shown in FIG.
Step S8 corresponds to the feedforward (phase) compensation calculation unit 31 shown in FIG. 4, where the feedforward (phase) compensator Gff (s) is used and the above basic clutch transmission torque capacity target value tTclbase is used. Is subjected to phase compensation to calculate a feedforward control clutch transmission torque capacity target value tTclff.

In calculating the feedforward control clutch transmission torque capacity target value tTclff, the calculation is actually performed using the following recurrence formula obtained by discretization by Tustin approximation or the like.
(Tclff / tTclbase) = G _FF (s) = {Gclref (s) / Gcl (s)}
＝ (τ _cl・ s + 1) / (τ _clref・ s + 1) (6)
τ _cl : Model time constant of clutch
τ _clref ： Standard response time constant for clutch control

Step S9 corresponds to the clutch output side rotational speed target value calculation unit 32 shown in FIG. 4. Here, first, the basic clutch transmission torque capacity target value tTclbase and the vehicle on a flat road determined in advance are used. By calculating the following equation based on the running resistance Tr (where Tr is a value converted to the clutch output side), the output side drive torque target value tTo of the second clutch 7 is obtained,
tTo = tTclbase−Tr (7)
Next, the second clutch output side drive torque target value tTo, the vehicle inertia moment Jo, the speed ratio Gm determined by the selected gear stage of the automatic transmission 4 in the wheel drive system, and the final speed of the final reduction gear 8 in the wheel drive system Based on the reduction ratio Gf, the clutch output side rotational speed target value tNo of the second clutch 7 is
tNo / tTo = {(Gm · Gf) ² / Jo} × (1 / s) (7)
Calculated by

In the next step S10 of FIG. 2, although not shown in FIG. 4, the clutch output side rotational speed target value tNo of the second clutch 7 obtained in step S9 is the upper limit value tNomax obtained by the following equation, that is, The clutch output side rotational speed target value tNo is limited so as not to exceed the clutch output side rotational speed upper limit tNomax obtained by subtracting the minimum clutch slip amount Nslipmin from the input side rotational speed Ni of the second clutch 7.
tNomax ＝ Ni−Nslipmin (8)

  The next step S11 corresponds to the clutch output-side rotational speed reference value calculation unit 33 in FIG. 4, and here, the above-mentioned clutch output-side rotational speed target value is added to the reference model Gclref (s) of the second clutch 7. Through tNo, a clutch output side rotational speed reference value Noref for matching with this reference model is calculated.

In calculating the clutch output side rotational speed reference value Noref, the calculation is actually performed using the following recurrence formula obtained by discretization by Tustin approximation or the like.
(Noref / tNo) ＝ Gclref (s)
= 1 / (τ _clref · s + 1) (9)
τ _clref ： Standard response time constant for clutch control

  In the clutch output side rotational speed deviation calculating unit 34 of FIG. 4, the clutch output side rotational speed deviation Noerr (= Noref−No) between the clutch output side rotational speed standard value Noref and the clutch output side rotational speed detection value No. ) Is calculated.

Step S12 in FIG. 2 corresponds to the clutch transmission torque capacity correction value calculation unit 35 in FIG. 4, and is for setting the clutch output side rotational speed deviation Noerr to 0, that is, the clutch output side rotational speed reference value. A clutch transmission torque capacity correction value Tclfb, which is a feedback control amount of the clutch transmission torque capacity for making the clutch output side rotational speed detection value No coincide with Noref, is calculated.
In calculating the clutch transmission torque capacity correction value Tclfb, the calculation is actually performed using the following recurrence formula obtained by discretization by Tustin approximation or the like.
Tclfb = {Kclp + (Kcli / s)} · Noerr (10)
Kclp: Proportional control gain
Kcli: integral control gain

Steps S13 and S16 in FIG. 2 correspond to the clutch output side rotational speed control clutch transmission torque capacity target value calculation unit 36 in FIG.
In step S13, the above-described feedforward control clutch transmission torque capacity target value tTclff and the above-described clutch transmission torque capacity correction value Tclfb are added together to obtain the clutch output torque control target clutch transmission torque capacity value Tclfbon. Seeking
In step S16, this clutch output side rotational speed control clutch transmission torque capacity target value Tclfbon is set as the final clutch transmission torque capacity target value tTcl.

  On the other hand, when it is determined in step S6 that the engagement control based on the output side rotational speed No of the second clutch 7 as a basic premise of the present invention should not be performed, the control proceeds to step S14, and the clutch output side in step S9 is determined. The rotation speed target value tNo is initialized to the clutch output side rotation speed detection value No, and the integrator used when obtaining the clutch transmission torque capacity correction value Tclfb in step S12 is initialized to 0.

In the next step S15, in response to the determination that the engagement control based on the output side rotational speed No of the second clutch 7 should not be performed in step S6, the second clutch 7 is brought into the engaged state or the released state. Clutch normal torque clutch transmission torque capacity target value Tclfboff for maintaining these steady states, or until the second clutch 7 starts to be engaged and controlled based on the output side rotational speed No. The clutch transmission torque capacity target value Tclfboff for clutch normal control at is obtained.
Note that the clutch normal control clutch transmission torque capacity target value Tclfboff for putting the second clutch 7 into the engaged state or maintaining this steady state is set to the maximum value that the second clutch 7 can realize, and the second clutch 7 is released. The clutch normal control clutch transmission torque capacity target value Tclfboff for changing to the normal state or maintaining the steady state is gradually reduced from the current transmission torque capacity of the second clutch 7.

In step S16, as described above in response to determining that the engagement control based on the output side rotational speed No of the second clutch 7 should be performed when the loop passing through the steps S8 to S13 is selected, The clutch output torque capacity target value Tclfbon for clutch output side rotational speed control obtained in step S13 is set as the final clutch transfer torque capacity target value tTcl,
When the loop passing through step S14 and step S15 is selected, in response to determining that the engagement control based on the output side rotational speed No of the second clutch 7 should not be performed, the clutch normal control obtained in step S15 The clutch transmission torque capacity target value Tclfboff is set as the final clutch transmission torque capacity target value tTcl.

In the next step S17, the hydraulic solenoid current of the second clutch 7 for achieving the final clutch transmission torque capacity target value tTcl determined as described above is determined as follows.
That is, first, the clutch hydraulic pressure of the second clutch 7 that realizes the final clutch transmission torque capacity target value tTcl is searched based on the map scheduled to be illustrated in FIG. 7, and then the clutch is determined based on the map illustrated in FIG. The hydraulic solenoid current of the second clutch 7 that generates the hydraulic pressure is determined.
In step S17, the hydraulic solenoid current of the second clutch 7 thus determined is supplied to the corresponding clutch controller 26, and this controller causes the second clutch 7 to have its transmission torque capacity set to the final clutch transmission torque capacity target value tTcl. The fastening is controlled so as to match.

By the way, in this embodiment, in particular, the configuration as shown in the block diagram of FIG.
The basic clutch transmission torque capacity target value calculation means 41 calculates the basic transmission torque capacity target value tTclbase of the second clutch 7 according to the vehicle driving operation and the vehicle running state as described above for step S7,
The clutch output side rotational speed target value calculating means 42 calculates the target value tNo of the output side rotational speed of the second clutch 7 from the basic clutch transmission torque capacity target value tTclbase, as described above for step S9.

  In the clutch output side rotational speed control transmission torque capacity target value calculation means 43, as described above for step S12 and step S13, the clutch output side rotational speed target value tNo and the clutch output side rotational speed detection value detected by the sensor 14 are detected. The clutch output side torque deviation Noerr (= Noref−No) between No and No is set to 0, and the clutch transmission torque capacity for making the clutch output side rotational speed target value tNo coincide with the clutch output side rotational speed detection value No. A feedback correction amount Tclfb is calculated, and the clutch transmission torque capacity target value tTclff for feedforward control obtained in step S8 is corrected by this feedback correction amount Tclfb to obtain a clutch transmission torque capacity target value Tclfbon for clutch output side rotational speed control. To do.

The second clutch engagement transmission torque capacity target value calculating means 44 corresponds to the motor torque target value tTm including that for step S4 or the step S5 and steps S22 to S25 obtained for the downhill road as described above. The clutch capacity tTclon (which can transmit this motor torque without slipping) is calculated.
The clutch slip control flag generating means 45 commands the release of the second clutch 7 by setting the clutch slip control flag FLAG to 0 while the second clutch 7 is to be released,
When the slip control of the second clutch 7 should be started, the clutch slip control flag FLAG is set to 1, and the slip control start of the second clutch 7 is commanded.
Although the clutch transmission torque capacity target value Tclfbon for clutch output side rotational speed control is 0 indicating the release of the second clutch 7, the output side rotational speed No of the second clutch 7 is increased due to traveling on a downhill road. Until the rotational speed within the predetermined deviation with respect to the input side rotational speed Ni of the second clutch (until the input / output side rotational speed difference of the second clutch 7, that is, until the slip amount becomes less than the predetermined value), the clutch The slip control flag FLAG is kept at 1 to instruct the second clutch 7 to continue the slip control,
While the second clutch 7 is to be engaged, the clutch slip control flag FLAG is set to 2 to command the engagement of the second clutch 7.

While the clutch slip control flag FLAG is 1 (slip control command), the clutch transmission torque capacity target value selection means 46 uses the clutch transmission torque capacity target value Tclfbon for clutch output side rotational speed control from the means 43 as the clutch transmission torque capacity. Used as the target value tTcl for engagement control of the second clutch 7,
While the clutch slip control flag FLAG is 0 (release command) or 2 (engagement command), the clutch capacity tTclon corresponding to the motor torque target value tTm from the means 44 (this motor torque can be transmitted without slipping) is set. The clutch transmission torque capacity target value tTcl is used for engagement control of the second clutch 7.

Therefore, in the embodiment shown in FIG. 9, the following operational effects can be achieved as is apparent from FIG. 10 showing the operation time chart under the same conditions as in FIG.
FIG. 10 shows that when the output of the motor / generator torque Tm starts from the instant t1, the input side (motor / generator side) rotational speed Ni of the second clutch 7 is increased as shown in the figure.
From the instant t2, the second clutch 7 starts to be engaged by increasing the transmission torque capacity Tc2, and the vehicle starts to run by increasing the output side (drive wheel side) rotational speed No of the second clutch.
From the instant t3, the transmission torque capacity Tc2 of the second clutch 7 is controlled so that the output speed No coincides with the target value tNo (the second clutch slip control flag FLAG = 1),
After the instant t4, as the result of the transition from flat road traveling to downhill road traveling and the output side rotational speed No increasing, the transmission torque capacity Tc2 becomes 0 by the slip control of the second clutch 7, and the second clutch 7 is It is an operation | movement time chart at the time of releasing.

In this embodiment, even if the second clutch 7 is released after the instant t4, the slip control for keeping the output side rotational speed No at the target value is not terminated, and this slip control is performed as indicated by the flag FLAG = 1. Let it continue.
Even during this slip control, the second clutch 7 remains in the disengaged state, and the drive wheels are kept disconnected from the motor / generator 1 and the engine 2. Therefore, the output side rotational speed No of the second clutch 7 is It gradually increases as shown in the figure as the rotation of the drive wheel due to traveling downhill is increased.

Conventionally, as described above with reference to FIG. 13, the output side rotational speed No of the second clutch 7 further increases as shown in the figure after the instant t5 when it coincides with the input side rotational speed Ni.
In other words, after t4 at the time of downhill transition, even if the accelerator pedal is released, the driving wheel rotation speed increases as described above, but the engine brake cannot be used, resulting in insufficient deceleration, The regenerative braking by the generator cannot be performed, resulting in a decrease in energy efficiency.

By the way, in the present embodiment, the clutch output torque control clutch transmission torque capacity target value Tclfbon (second clutch transmission torque capacity Tc2) for clutch output side rotational speed control is 0 indicating the release of the second clutch 7, but the second clutch After the instant t5 in FIG. 10 when the output side rotational speed No. 7 rises due to traveling on the downhill road and becomes the rotational speed within the predetermined deviation with respect to the input side rotational speed Ni of the second clutch (after the downhill road traveling judgment time) To set the clutch slip control flag FLAG to 2 to command the engagement of the second clutch 7,
Instead of the clutch output torque capacity target value Tclfbon for clutch output side rotational speed control, the clutch capacity tTclon corresponding to the motor torque target value tTm obtained by the means 44 is used for the engagement control of the second clutch 7 as the clutch transmission torque capacity target value tTcl. Thus, the second clutch 7 is engaged with a capacity capable of transmitting the motor torque target value tTm.

Therefore, the driving wheel is coupled to the motor / generator 1 via the second clutch 7 from the instant t5, so that the wheel drive system can be prevented from rotating and rising due to the regenerative braking of the motor / generator 1. From t5, the output side rotational speed No (vehicle speed VSP) of the second clutch 7 can be kept constant as shown in the figure.
Therefore, the regenerative braking by the motor / generator 1 cannot be used as in the conventional case, so that the energy efficiency is not lowered or the deceleration is not insufficient.
By the way, although the above has described the case of EV traveling, during HEV traveling with the first clutch 6 also engaged, the engine brake can be used, and the above-described lack of deceleration can be more reliably resolved.

In the above embodiment, the output side drive torque target value tTo of the second clutch 7 is obtained by obtaining the motor rotation speed target value tNm obtained in step S22 of FIG. 3 by the calculation of the equations (1) and (2). The motor speed target value tNm to achieve
Instead, the motor rotation speed target value tNm is calculated by the following equation in step S22 of FIG. 3, and the motor rotation for achieving the target slip rotation tNslip (predetermined negative value) when the second clutch 7 travels on the downhill road. The numerical target value tNm may be used.
tNm ＝ Gm × No ＋ tNslip (11)
Gm: Gear ratio of automatic transmission 4
No: Output speed detection value of the second clutch 7

In the case of this embodiment, the configuration is as shown by a block diagram in FIG. 11. In FIG. 11, blocks that function in the same manner as in FIG. 9 are given the same reference numerals.
In the downhill road running motor torque target value calculation means 47, as in steps S21 to S25 in FIG. 3, the downhill road running motor torque target value tTm (in HEV running, the downhill road running engine torque target value is included). Calculate the power source torque target value when running on a slope.
In other words, the transmission torque capacity target value tTc2 of the second clutch 7 is 0 (the second clutch 7 is released), but the output side rotational speed No of the second clutch 7 increases and the input side rotational speed of the second clutch 7 When the rotational speed is within a predetermined deviation with respect to Ni (during downhill road traveling determination) and thereafter (step S21),
By calculating the equation (11), a motor rotation speed target value tNm required for the second clutch 7 to be the downhill road target slip rotation tNslip (predetermined negative value) is obtained (step S22),
A motor torque correction amount ΔTmfb necessary to achieve the motor rotation speed target value tNm is calculated (step S24),
The motor torque target value tTm obtained in step S4 of FIG. 2 is corrected by this motor torque correction amount ΔTmfb (tTm + ΔTmfb) to obtain a motor torque target value (denoted by the same sign tTm) during downhill travel (step S25).
This contributes to driving force control of the motor / generator 1 as shown in FIG.

In the present embodiment, the second clutch slip control transmission torque capacity target value calculation means 48 instead of the second clutch engagement transmission torque capacity target value calculation means 44 of FIG. The clutch capacity tTclslip necessary to realize the desired target slip rotation tNslip (predetermined negative value) is obtained.
Further, in the clutch slip control flag generating means 49 having the same name in place of the clutch slip control flag generating means 45 in FIG. 9, the clutch slip control flag FLAG is kept at 1 after the above-described downhill road traveling determination and a command to continue slip control is given. At the same time, a downhill traveling determination signal is output.

The clutch transmission torque capacity target value selection means 46 is a clutch output side rotational speed control clutch from the means 43 while the clutch slip control flag FLAG is 1 (slip control command) and no downhill traveling determination signal is output. The transmission torque capacity target value Tclfbon is used as the clutch transmission torque capacity target value tTcl for the engagement control of the second clutch 7,
While the clutch slip control flag FLAG is 1 (slip control command) and the downhill road traveling determination signal is output, or while the clutch slip control flag FLAG is 0 (release command) or 2 (engagement command) The clutch capacity tTclon corresponding to the motor torque target value tTm from 44 (this motor torque can be transmitted without slipping) is used as the clutch transmission torque capacity target value tTcl for the engagement control of the second clutch 7.

In the present embodiment shown in FIG. 11, the following operational effects can be achieved, as is apparent from FIG. 12, which shows an operation time chart under the same conditions as in FIG.
FIG. 12 shows that the input side (motor / generator side) rotational speed Ni of the second clutch 7 is increased as shown in FIG.
From the instant t2, the second clutch 7 starts to be engaged by increasing the transmission torque capacity Tc2, and the vehicle starts to run by increasing the output side (drive wheel side) rotational speed No of the second clutch.
From the instant t3, the transmission torque capacity Tc2 of the second clutch 7 is controlled so that the output speed No coincides with the target value tNo (the second clutch slip control flag FLAG = 1),
After the instant t4, as the result of the transition from flat road traveling to downhill road traveling and the output side rotational speed No increasing, the transmission torque capacity Tc2 becomes 0 by the slip control of the second clutch 7, and the second clutch 7 is It is an operation | movement time chart at the time of releasing.

In this embodiment, even if the second clutch 7 is released after the instant t4, the slip control for keeping the output side rotational speed No at the target value is not terminated, and this slip control is performed as indicated by the flag FLAG = 1. Let it continue.
Even during this slip control, the second clutch 7 remains in the disengaged state, and the drive wheels are kept disconnected from the motor / generator 1 and the engine 2. Therefore, the output side rotational speed No of the second clutch 7 is It gradually increases as shown in the figure as the rotation of the drive wheel due to traveling downhill is increased.

Conventionally, as described above with reference to FIG. 13, the output side rotational speed No of the second clutch 7 further increases as shown in the figure after the instant t5 when it coincides with the input side rotational speed Ni.
In other words, after t4 at the time of downhill transition, even if the accelerator pedal is released, the driving wheel rotation speed increases as described above, but the engine brake cannot be used, resulting in insufficient deceleration, The regenerative braking by the generator cannot be performed, resulting in a decrease in energy efficiency.

By the way, in the present embodiment, the clutch output torque control clutch transmission torque capacity target value Tclfbon (second clutch transmission torque capacity Tc2) for clutch output side rotational speed control is 0 indicating the release of the second clutch 7, but the second clutch Even after the instant t5 in FIG. 12 when the output side rotational speed No. 7 rises due to traveling on a downhill road and reaches a rotational speed within a predetermined deviation from the input side rotational speed Ni of the second clutch (after the downhill road traveling judgment time) Continue to issue a slip control continuation command for the second clutch 7 by setting the clutch slip control flag FLAG to 1.
The motor / generator 1 (motor torque Tm) is driven and controlled so that the slip amount of the second clutch 7 becomes the target slip rotation tNslip (predetermined negative value) during downhill travel, and the target slip rotation tNslip during downhill travel is In order to control the transmission torque capacity Tc2 of the second clutch 7 so as to be obtained, the second clutch 7 is engaged in the slip state of the target slip rotation tNslip when traveling downhill.

Therefore, the driving wheel is coupled to the motor / generator 1 via the second clutch 7 from the instant t5, so that the wheel drive system can be prevented from rotating and rising due to the regenerative braking of the motor / generator 1. From t5, the output side rotational speed No (vehicle speed VSP) of the second clutch 7 can be kept constant as shown in the figure.
Therefore, the regenerative braking by the motor / generator 1 cannot be used as in the conventional case, so that the energy efficiency is not lowered or the deceleration is not insufficient.
Although the above has been described for EV travel, during HEV travel with the first clutch 6 also engaged, the engine brake can be used, and the above-described lack of deceleration can be more reliably resolved.

By the way, in the present embodiment, during traveling downhill, the second clutch 7 is in a slip state of the target slip rotation tNslip during downhill traveling so that the above-described effect is achieved.
When the second clutch 7 has been driven on the downhill road and the second clutch 7 is subjected to the engagement capacity control (slip control) so that the output side rotational speed matches the target value, the restart of the slip control of the second clutch 7 is from the slip state. Thus, the slip control can be restarted with high response.

It is a basic diagram which shows the power train of the hybrid vehicle provided with the downhill road traveling control apparatus which becomes one Example of this invention with the control system. 2 is a flowchart showing a control program for downhill traveling control executed by an integrated controller in FIG. FIG. 3 is a flowchart showing a subroutine related to motor torque target value correction control during downhill road travel in the downhill road travel control of FIG. 2; FIG. 3 is a functional block diagram of clutch engagement control in downhill road traveling control shown in FIG. It is a characteristic diagram used when calculating | requiring a wheel drive torque target value. FIG. 4 is a characteristic diagram used when obtaining the transmission torque capacity of the second clutch in FIG. It is a characteristic diagram used when the clutch hydraulic pressure corresponding to a clutch transmission torque capacity target value is calculated | required. FIG. 8 is a characteristic diagram used when obtaining a hydraulic solenoid current for generating the clutch oil pressure obtained based on FIG. It is a block diagram according to function which shows one Example of the downhill road traveling control by this invention only about a summary part. 10 is an operation time chart of downhill road traveling control shown in FIG. It is a block diagram according to function which shows other examples of downhill road running control by the present invention only about a summary part. 12 is an operation time chart of downhill road traveling control shown in FIG. It is an operation | movement time chart by the conventional downhill road driving control.

Explanation of symbols

1 Motor / Generator 2 Engine
3L, 3R Left and right drive wheels 4 Automatic transmission 5 Motor / generator shaft 6 First clutch 7 Second clutch 8 Final reduction gear
11 Accelerator position sensor
12 Vehicle speed sensor
13 Clutch input side rotation sensor
14 Clutch output side rotation sensor
20 Integrated controller
21 battery
22 Inverter
23 Battery controller
24 Engine controller
25 Motor / generator controller
26 Clutch controller
27 Transmission controller
31 Feedforward compensation calculation section
32 Clutch output side rotation speed target value calculation section
33 Clutch output side rotation speed reference value calculator
34 Clutch output side rotational speed deviation calculator
35 Clutch transmission torque capacity correction value calculator
36 Final clutch transmission torque capacity target value calculator
41 Basic clutch transmission torque capacity target value calculation means
42 Clutch output side rotation speed target value calculation means
43 Clutch output side rotational speed control transmission torque capacity target value calculation means
44 Transmission torque capacity target value calculation means for second clutch engagement
45 Clutch slip control flag generation means
46 Clutch transmission torque capacity target value selection means
47 Motor torque target value calculation means when traveling downhill
48 Transfer torque capacity target value calculation means for second clutch slip control
49 Clutch slip control flag generation means

Claims (2)

An engine and a motor / generator are provided as the power source, and a first clutch capable of changing the transmission torque capacity is interposed between the engine and the motor / generator to transmit to a wheel drive system including a transmission from the motor / generator to the drive wheels. Insert the second clutch that can change the torque capacity,
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, and by engaging both the first and second clutches, the engine And a hybrid vehicle that can select a hybrid driving mode by power from both the motor / generator,
While the second clutch is slip-controlled so that the driving wheel side rotation speed of the second clutch becomes a target value, the driving wheel side rotation speed of the second clutch is also released after the second clutch is released. Rises to a rotational speed within a predetermined deviation from the rotational speed on the motor / generator side of the second clutch.
A downhill traveling control device for a hybrid vehicle, wherein a second clutch is engaged and a wheel drive system between the second clutch and driving wheels is regeneratively braked by a motor / generator. An engine and a motor / generator are provided as the power source, and a first clutch capable of changing the transmission torque capacity is interposed between the engine and the motor / generator to transmit to a wheel drive system including a transmission from the motor / generator to the drive wheels. Insert the second clutch that can change the torque capacity,
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, and by engaging both the first and second clutches, the engine And a hybrid vehicle that can select a hybrid driving mode by power from both the motor / generator,
While the second clutch is slip-controlled so that the driving wheel side rotation speed of the second clutch becomes a target value, the driving wheel side rotation speed of the second clutch is also released after the second clutch is released. Rises to a rotational speed within a predetermined deviation from the rotational speed on the motor / generator side of the second clutch.
The motor / generator side rotation speed of the second clutch is made less than the driving wheel side rotation speed by the output control of the power source, and the slip control of the released second clutch is resumed. A downhill traveling control device for a hybrid vehicle.

Images