JP2012240566A - Electric travel controller for hybrid vehicle - Google Patents

Abstract

An acceleration torque margin that is left for realizing an acceleration request is reduced when it is estimated that there is no acceleration request, the motor torque for electric traveling is increased, and the motor traveling area is expanded.
When estimating that “acceleration request is present” in S11, the acceleration torque margin Tac for realizing the acceleration request during EV driving is reset to the initial value (maximum value) in S12, and “no acceleration request is present in S11. In step S13, the acceleration torque margin Tac is reduced by ΔTac from the initial value (maximum value). When there is no acceleration request, the electric running motor torque is increased by the amount of decrease in the acceleration torque margin Tac (ΔTac), and the electric running area can be expanded to a higher vehicle speed by using only the motor torque. Can be improved.
[Selection] Figure 2

Description

  The present invention uses an engine, a first clutch, a motor / generator, a second clutch, and a drive wheel in the order of arrangement of transmission paths, and performs electric travel only by the motor / generator by the engagement / release control of the first clutch and the second clutch. The present invention relates to an electric travel control device for a hybrid vehicle capable of selecting whether to perform hybrid travel by cooperation of an engine and a motor / generator, and particularly to a control technique related to an acceleration torque margin during electrical travel.

  As the hybrid vehicle as described above, for example, as described in Patent Document 1, a motor / generator is coupled and interposed between the engine and the drive wheel, and the engine and the motor / generator can be connected and disconnected by the first clutch. None, a so-called one-motor two-clutch parallel hybrid vehicle is known in which a motor / generator and a driving wheel can be connected / disconnected by a second clutch.

  In this hybrid vehicle, when the first clutch is released and the second clutch is engaged, it is possible to select an EV mode in which electric (EV) traveling is performed only by the motor / generator. Both the first clutch and the second clutch By fastening, it is possible to select a HEV mode in which hybrid (HEV) traveling by cooperation of the motor / generator and the engine is performed.

  In such a one-motor two-clutch parallel hybrid vehicle, during driving in EV mode selected at low load and low rotation, for example, the required driving force (required acceleration) increases due to depression of the accelerator pedal, and only by the motor / generator When this required driving force (required acceleration) cannot be realized, the mode is switched to HEV running (HEV mode) by the cooperation of the motor / generator and the engine.

  When starting the engine required for this EV → HEV mode switching, the first clutch that has been released in the EV mode is engaged, and the engine is started using the motor torque (cranking torque) from the motor / generator.

JP 2010-179865 A

  However, the motor / generator rated torque corresponds to the vehicle's running resistance (air resistance, rolling resistance, etc.) in order to guarantee the engine start described in Patent Document 1 and to realize the acceleration demand of the vehicle. Drive torque and the sum of the acceleration torque margin corresponding to the predetermined acceleration margin for realizing the acceleration request and the torque for electric (EV) running and the engine starting torque (cranking torque) It needs to be big enough to cover.

By the way, the motor / generator is required to be reduced in size by reducing the rated torque as much as possible from the viewpoint of cost and mounting space, and is limited by the magnitude of the rated torque.
However, even if the motor / generator rated torque is limited in this way, the necessary acceleration torque margin and cranking torque are generally determined and cannot be reduced.

In particular, the former acceleration torque margin is for generating vehicle acceleration without delay in response to the acceleration request when the driver issues an acceleration request by the accelerator operation. Conventionally, the acceleration torque margin is set to a relatively large torque value so that the acceleration can be generated.
For the latter cranking torque, the maximum request is made so that the engine starts with a response in response to the maximum required acceleration in the scene where the maximum acceleration is required, and the driving force of the vehicle increases as required without delay. It is common to set a large value based on the acceleration.

However, in a situation where it is clear that the driver does not issue an acceleration request due to the accelerator operation, the vehicle may be driven against running resistance (air resistance, rolling resistance, etc.), and the acceleration torque margin Very little is required.
Therefore, while there is no acceleration request, the acceleration torque margin determined as described above is excessive.
For this reason, in a scene where there is no acceleration request, the drive torque obtained by subtracting the acceleration torque margin and the cranking torque from the motor / generator rated torque is unnecessarily reduced due to an excess of the acceleration torque margin.

As the drive torque becomes smaller, the motor / generator alone will not be able to run in the EV mode due to insufficient torque. (From a low vehicle speed), the vehicle will start running in the HEV mode in cooperation with the engine. The mode must be switched early (from low vehicle speed).
This means that the EV mode region intended to improve the fuel consumption rate is narrowed, resulting in a problem that the fuel consumption of the vehicle is deteriorated.

The present invention recognizes that the cause of the above problem is that the acceleration torque margin is set larger on the basis of the maximum acceleration request, and the large acceleration torque margin is used as it is regardless of whether or not there is an acceleration request. Based on
By adjusting the acceleration torque margin according to whether or not there is an acceleration request so that it does not become excessive when there is no acceleration request, the EV mode region becomes narrower and the fuel efficiency of the vehicle deteriorates. An object of the present invention is to provide an electric travel control device for a hybrid vehicle that does not cause a problem.

  For this purpose, the electric travel control device for a hybrid vehicle according to the present invention has the following configuration.

First, to explain the premise hybrid vehicle,
The engine, the first clutch, the motor / generator, the second clutch, and the driving wheel are arranged in the transmission path arrangement order, and the motor / generator among the engine and the motor / generator is controlled by the engagement / release control of the first clutch and the second clutch. It is possible to select whether to use electric generator only by generator or hybrid driving by cooperation of engine and motor / generator,

In addition, the electric travel control device used as a premise for such a hybrid vehicle is:
At the time of steady electric traveling, the motor / generator drives the wheels while leaving at least an acceleration torque margin for realizing the acceleration request of the vehicle.

And this invention is characterized by the structure which provided the following acceleration request estimation means and the acceleration torque margin adjustment means with respect to this electric travel control apparatus.
The former acceleration request estimation means estimates the presence or absence of the acceleration request,
The latter acceleration torque margin adjustment means reduces the acceleration torque margin when the acceleration request estimation means estimates that there is no acceleration request.

According to the electric travel control device for a hybrid vehicle according to the present invention described above, when it is estimated that there is no acceleration request, in order to reduce the acceleration torque margin,
When there is no acceleration request, the acceleration torque margin does not become excessive with respect to the acceleration request.

Therefore, when there is no acceleration request, the driving torque obtained by subtracting the acceleration torque margin and cranking torque from the rated torque of the motor / generator is not reduced.
It is possible to postpone the arrival of a state in which electric driving by only the motor / generator becomes impossible (mode switching to hybrid driving), and the electric driving area intended to improve the fuel consumption rate can be expanded to higher vehicle speeds and fuel consumption The above-mentioned problem that the fuel consumption of the vehicle deteriorates can be solved.

1 is a schematic system diagram showing a power train of a hybrid vehicle including an electric travel control device according to an embodiment of the present invention, together with its control system. 2 is a flowchart of a control program executed by the hybrid controller of the powertrain control system in FIG. 1 to control an acceleration torque margin during EV travel. FIG. 2 is a diagram used for explaining a point when determining a motor output possible torque (rated torque) of the motor / generator in FIG. 1; When the acceleration torque margin is the initial value (maximum value), the motor / generator can be used for EV driving out of the motor output maximum driving force based on the motor output possible torque (rated torque) shown in Fig. 3. It is a diagram which shows a possible drive force with the request drive force at the time of EV driving | running | working. FIG. 3 is an explanatory diagram showing a control range for an acceleration torque margin in a case where adjustment control for an acceleration torque margin is performed by the control program of FIG. 2 in terms of motor output. FIG. 3 is a diagram showing a change characteristic of a fuel efficiency improvement rate achieved by adjustment control for an acceleration torque margin shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
<Powertrain for hybrid vehicles>
FIG. 1 shows a power train of a hybrid vehicle including an electric travel control device according to an embodiment of the present invention, along with its control system.
This hybrid vehicle is based on a front engine / front wheel drive vehicle (front wheel drive vehicle), and is a hybrid of this.
In FIG. 1, reference numeral 1 denotes an engine as a power source, 2FL and 2FR denote left and right front wheels (right and left drive wheels), and 3RL and 3RR denote left and right rear wheels (left and right driven wheels), respectively.

  In the hybrid vehicle powertrain shown in FIG. 1, a V-belt continuously variable transmission 4 is arranged on one side in the vehicle width direction of the engine 1 mounted horizontally as in the case of a normal front-wheel drive vehicle. The motor / generator 6 (MG: power source) is connected to the shaft 5 for transmitting the rotation from the crankshaft 1a) to the input shaft 4a of the V-belt type continuously variable transmission 4.

The motor / generator 6 includes an annular stator fixed in a housing and a rotor arranged concentrically with a predetermined air gap in the annular stator, and an electric motor ( Acting as an electric motor) or acting as a generator (generator), it is arranged between the engine 1 and the V-belt type continuously variable transmission 4.
The motor / generator 6 passes through the shaft 5 and is bonded to the center of the rotor, and this shaft 5 is used as a motor / generator shaft.

The first clutch 7 (CL1) is inserted between the motor / generator 6 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 are generated by the first clutch 7. 6 are separably connected.
Here, it is assumed that the first clutch 7 is capable of continuously changing the transmission torque (clutch engagement) capacity. For example, the first clutch 7 continuously controls the clutch hydraulic oil flow rate and the clutch operation hydraulic pressure with a proportional solenoid to transmit the transmission torque (clutch engagement). ) Consists of wet multi-plate clutch with variable capacity.

The motor / generator 6 and the V-belt type continuously variable transmission 4 are directly connected to each other by a direct connection between the motor / generator shaft 5 and the transmission input shaft 4a, and the second clutch 9 ( Insert CL2).
The V-belt type continuously variable transmission 4 may be a well-known one, but from now on, it is assumed that the torque converter is excluded and the motor / generator 6 is directly coupled to the transmission input shaft 4a instead.
If the transmission input shaft 4a is in the engaged state, the rotation from the input shaft 4a is shifted at a reduction ratio corresponding to the pulley ratio of the V-belt continuously variable transmission mechanism and output to the output shaft 4b.

The rotation output from the output shaft 4b of the V-belt type continuously variable transmission 4 is transmitted to the left and right front wheels 2FL and 2FR via a differential gear device (not shown) and used for traveling of the vehicle.
However, it goes without saying that the V-belt type continuously variable transmission 4 may be a stepped automatic transmission.

The second clutch 9 (CL2), which is indispensable in a hybrid vehicle and releasably couples the motor / generator 6 and the drive wheels 2FL, 2FR, can be used instead of being inserted in the middle of the transmission input shaft 4a as shown in FIG. In addition, it may be installed at the rear stage of the V-belt type continuously variable transmission 4.
However, the second clutch 9 can change the transmission torque capacity (clutch engagement capacity) continuously, as with the first clutch 7 described above.

In the following, the driving mode of the powertrain described above with reference to FIG. 1 will be described.
In the power train shown in FIG. 1, when electric driving (EV mode) used at low load and low vehicle speed including when starting from a stopped state is required, the first clutch 7 is released and the second clutch 9 is concluded.

When the motor / generator 6 is driven in this state, only the output rotation from the motor / generator 6 reaches the transmission input shaft 4a, and the V-belt continuously variable transmission 4 rotates the input shaft 4a. The speed is changed according to the selected pulley ratio and output from the transmission output shaft 4b.
The rotation from the transmission output shaft 4b then reaches the front wheels 2FL and 2FR via a differential gear device (not shown), and the vehicle can be electrically driven (EV traveling) only by the motor / generator 6.

When hybrid travel (HEV mode) used during high speed travel or heavy load travel is required, the first clutch 7 is engaged and the second clutch 9 is engaged.
In this state, both the output rotation from the engine 1 and the output rotation from the motor / generator 6 reach the transmission input shaft 4a in cooperation, and the V-belt type continuously variable transmission 4 is connected to the input shaft 4a. The rotation is changed according to the selected pulley ratio and output from the transmission output shaft 4b.
Thereafter, the rotation from the transmission output shaft 4b reaches the front wheels 2FL and 2FR via a differential gear device (not shown), and the vehicle can be hybrid-driven (HEV-driven) by the cooperation of the engine 1 and the motor / generator 6.

  In such HEV traveling, if the engine 1 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 6 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 6, the fuel consumption of the engine 1 can be improved.

In selecting the EV mode and the HEV mode, the mode selection is generally performed as follows.
When the vehicle speed is a predetermined vehicle speed (e.g. 30 km / h) or less, the accelerator opening is a predetermined opening (e.g. 1/8) or less, or the accelerator opening change rate is a predetermined acceleration request (e.g. 0.05 G) or less, and the motor / generator rotation speed Is a motor / generator 6 only when the engine cooling water temperature is equal to or higher than a predetermined water temperature (for example, 40 ° C.) and the battery storage state SOC is equal to or higher than a predetermined power storage state (for example, 60%). To select the EV mode for electric (EV) driving.

  If one of the above EV mode selection conditions is missing, that is, for example, when the accelerator pedal is depressed in the EV driving state, the accelerator opening exceeds a predetermined opening (1/8), or the accelerator opening change rate is When the predetermined acceleration requirement (0.05G) is exceeded, or when the battery charge state SOC falls below the predetermined charge state (60%), the HEV mode that performs hybrid (HEV) running by the cooperation of the engine 1 and the motor / generator 6 Command selection.

Next, a control system of the engine 1, the motor / generator 6, the first clutch 7 (CL1), and the second clutch 9 (CL2) that constitute the power train of the hybrid vehicle described above will be schematically described with reference to FIG.
This control system includes a hybrid controller 11 that performs integrated control of the operating point of the power train. The operating point of the power train includes the target engine torque tTe, the target motor / generator torque tTm, and the target engagement capacity of the first clutch 7. It is defined by tTc1 (first clutch engagement pressure command value tPc1) and target engagement capacity tTc2 (second clutch engagement pressure command value tPc2) of the second clutch 9.

In order to determine the operating point of the power train, the hybrid controller 11
A signal from the engine speed sensor 12 for detecting the engine speed Ne;
A signal from the motor / generator rotation sensor 13 for detecting the motor / generator rotation speed Nm,
A signal from the input rotation sensor 14 for detecting the transmission input rotation speed Ni;
A signal from the output rotation sensor 15 for detecting the transmission output rotation speed No (vehicle speed VSP),
A signal from the accelerator opening sensor 16 for detecting the accelerator pedal depression amount (accelerator opening APO);
A signal from a storage state sensor 17 that detects a storage state SOC of the high-power battery 31 that stores power for the motor / generator 6 is input.

  The hybrid 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 engagement capacity tTc1, and second clutch target engagement capacity tTc2 are calculated.

  The target engine torque tTe is supplied to the engine controller 32. The engine controller 32 realizes the target engine torque tTe based on the engine speed Ne from the engine speed Ne detected by the sensor 12 and the target engine torque tTe. Therefore, the engine 1 is controlled so that the engine torque becomes the target engine torque tTe by the throttle opening control and the fuel injection amount control.

  The target motor / generator torque tTm is supplied to the motor controller 33. The motor controller 33 converts the electric power of the high-voltage battery 31 into DC-AC by the inverter 34, and controls the stator of the motor / generator 6 under the control of the inverter 34. Then, the motor / generator torque is controlled so that the motor / generator torque matches the target motor / generator torque tTm.

If the target motor / generator torque tTm is such that the motor / generator 6 requires a regenerative braking action, the motor controller 33 is connected to the battery storage state SOC detected by the sensor 17 via the inverter 34 in order to A power generation load is applied to the motor / generator 6 so that the battery 31 is not overcharged.
The electric power generated by the motor / generator 6 by regenerative braking is AC-DC converted by the inverter 34 and stored in the high-power battery 31.

  The first clutch target engagement capacity tTc1 is supplied to the first clutch controller 36, which detects the first clutch engagement pressure command value tPc1 corresponding to the first clutch target engagement capacity tTc1 and the sensor 19 By contrast with the engagement pressure Pc1 of the first clutch 7, the engagement pressure of the first clutch 7 is set via the first clutch engagement pressure control unit 37 so that the engagement pressure Pc1 of the first clutch 7 becomes the first clutch engagement pressure command value tPc1. To control the engagement capacity of the first clutch 7.

The second clutch target engagement capacity tTc2 is supplied to the transmission controller 38,
The transmission controller 38 compares the second clutch engagement pressure command value tPc2 corresponding to the second clutch target engagement capacity tTc2 with the engagement pressure Pc2 of the second clutch 9 detected by the sensor 20, and The engagement capacity of the second clutch 9 is controlled by controlling the engagement pressure of the second clutch 9 via the second clutch engagement pressure control unit 39 so that the engagement pressure Pc2 becomes the second clutch engagement pressure command value tPc2.

  The transmission controller 38 is a pulley suitable for the current operating state based on the planned shift map from the transmission output rotational speed No (vehicle speed VSP) detected by the sensor 15 and the accelerator opening APO detected by the sensor 16. The ratio is obtained, and the continuously variable transmission from the current pulley ratio to the preferred pulley ratio is also performed.

<Electric travel (acceleration torque margin) control>
The above is an outline of the normal control executed by the control system of FIG.
In the present embodiment, the hybrid controller 11 in FIG. 1 executes the engine start (cranking torque) control program shown in FIG. 2 to adjust the acceleration torque margin Tac during electric (EV) traveling as follows: Shall.

In step S11, it is estimated whether the driver is in a transient EV traveling that issues an acceleration request by an accelerator operation or a steady EV traveling without an acceleration request, and the estimation result is checked.
Therefore, step S11 corresponds to the acceleration request estimation means in the present invention.
There are the following methods for estimating the acceleration request, and the estimation can be performed using any one of them alone or in combination.

(1) When there is no change in the vehicle speed over the set time, it is steady EV driving or EV driving close to steady driving even if there is a slight acceleration request, and there will be no large acceleration request for a while after this Therefore, it is estimated that there is no acceleration request.
(2) If the vehicle speed increase that is not linked to the accelerator operation continues for the set time, the vehicle is accelerating even though there is no acceleration operation by the driver. Since it can be determined that the downhill road will continue for some time, it is estimated that there is no acceleration request.

(3) If the maximum vehicle speed during the past predetermined period has been below the predetermined value for more than the predetermined time, the maximum vehicle speed in the vehicle speed history is below the predetermined value and the vehicle is traveling on a congested road, and the traffic will continue for some time. Since it can be determined that the road continues, it is estimated that there is no acceleration request.
Note that the determination of a congested road based on the upper limit vehicle speed of the vehicle speed history may be performed in cooperation with the navigation system.
(4) When the inter-vehicle distance with the forward vehicle is less than or equal to the predetermined value, the vehicle is following the forward vehicle, and there is no request for acceleration to narrow the inter-vehicle distance, and for a while. Since it can be determined that the preceding vehicle follow-up running continues, it is estimated that there is no acceleration request.

(5) When the difference between the vehicle speed VSP and the speed regulation information on the navigation system is less than or equal to the predetermined value, the driver is driving according to the speed regulation information. Since it can be determined that it will continue, it is estimated that there is no acceleration request.
(6) When the state in which the steering amount during the past predetermined period is equal to or greater than the predetermined steering period continues for a predetermined period or longer, it can be determined from this steering history that the vehicle is traveling on a curved road. It is estimated that there is no acceleration request for a while.
(7) When the fuel efficiency-oriented driving mode is selected, the driver does not make an acceleration request that causes a deterioration in fuel efficiency, so it is estimated that there is no acceleration request.

(8) When the host vehicle speed VSP is low and the headlamp is lit in the automatic lighting mode, it can be determined that the vehicle is traveling in an indoor parking lot or a multistory parking lot, so it is estimated that there is no acceleration request.
In determining the traveling in the parking lot, the determination may be performed from the destination information and the current location information in the navigation system.
(9) When the driving environment including weather information and / or outside temperature does not require an acceleration request, that is, when the weather information recognizes that it is during or immediately after snowing, or when the outside temperature is extremely high If it is low and the road surface is suspected of being frozen, it is estimated that there is no acceleration request.
The meteorological information acquired as described above is not limited to snow and outside temperature, but may be obtained from various alarms and warnings.

  If it is determined in step S11 of FIG. 2 that the result of estimating the presence or absence of the acceleration request as described above is “acceleration request is present”, in step S12, an acceleration torque margin Tac for realizing the acceleration request during EV traveling is obtained. To the initial value.

Here, the initial value of the acceleration torque margin Tac will be described. The initial value of the acceleration torque margin Tac is determined by the vehicle acceleration without delay with respect to the acceleration request when the driver issues an acceleration request by the accelerator operation. The maximum value is set so as to always generate a predetermined acceleration or higher in any scene.
Therefore, in estimating whether or not there is an acceleration request in step S11, when it is estimated that the required acceleration is equal to or greater than the set acceleration near the maximum required acceleration corresponding to the initial value (maximum value) of the acceleration torque margin Tac, When it is determined that “there is an acceleration request” and it is estimated that the requested acceleration is less than the set acceleration, it is determined that “no acceleration request”.

Therefore, when it is determined in step S11 that “no acceleration request”, in step S13, the acceleration torque margin Tac is decreased from the initial value (maximum value) by a predetermined value ΔTac.
Therefore, step S13 corresponds to the acceleration torque margin adjustment means in the present invention.
The predetermined value ΔTac may be a fixed value, or may be set to a larger value as the difference value increases according to the difference value between the above-described maximum required acceleration and the current required acceleration.

By the way, when the acceleration torque margin Tac is reduced as described above, it is preferable to gradually decrease the acceleration torque margin Tac at a predetermined rate of change in time for shock countermeasures.
At this time, it is arbitrary whether the acceleration torque margin Tac is decreased stepwise or continuously changed.

Then, the adjustment lower limit value of the acceleration torque margin Tac is the margin torque that can generate the minimum acceleration of 0.01G, for example, the acceleration torque margin for which the acceleration response to the accelerator operation can be the minimum response required in average driving It is good to do.
Thus, when the lower limit of the acceleration torque margin Tac is set, it is possible to prevent the driver from feeling uneasy because the acceleration response to the accelerator operation is excessively reduced when the acceleration torque margin Tac is decreased.

In addition, as described in (2) above, when it is estimated that `` no acceleration request '' due to traveling downhill due to a vehicle speed increase not linked to the accelerator operation, the acceleration torque margin Tac is set to the vehicle speed increase rate not linked to the accelerator operation. And / or in accordance with the brake operating force, that is, depending on the road slope of the downhill road, it is preferable to decrease stepwise or continuously.
In this case, the acceleration torque margin Tac does not have an excess or deficiency with respect to the driver's required acceleration, but also does not have an excess or deficiency with respect to the slope of the downhill road.

When it is determined in step S11 that "no acceleration request", the reason for adjusting the acceleration torque margin Tac to a value smaller than the initial value (maximum value) in step S13 is as follows.
If the initial value (maximum value) of the acceleration torque margin Tac is continuously used over the entire driving range, the acceleration torque margin Tac becomes excessive for the small acceleration request in a situation where the driver does not make a large acceleration request. This is because the following problems occur.

The motor / generator 6 can drive the wheel while leaving a margin of acceleration torque margin Tac that realizes the acceleration request during steady EV traveling, and the engine 1 start required when switching from EV to HEV mode To be able to do
The motor output possible torque (rated torque) of the motor / generator 6 that exhibits the change illustrated in FIG. 3 with respect to the vehicle speed VSP (motor / generator rotation speed Nm) is the vehicle running resistance (air resistance, rolling resistance, etc.) ) And the torque (Tev) for electric (EV) driving, which is the sum of the acceleration torque margin Tac corresponding to the predetermined acceleration margin of the vehicle, and the cranking torque Tcr. The size needs to be obtained.

  By the way, from the viewpoint of cost and mounting space, the motor / generator 6 is required to reduce the motor output possible torque (rated torque) as much as possible and reduce the size, and the motor output possible torque (rated torque). Limited by the size of

However, while the possible motor output torque (rated torque) of the motor / generator 6 is limited, the cranking torque Tcr is set to a large value as described above, and the acceleration torque margin Tac is Even if there is no acceleration request, if you leave the initial value (maximum value) that can achieve this required acceleration at the time of acceleration request,
When there is no acceleration request, the acceleration torque margin Tac becomes excessive, and the drive torque Tdr obtained by subtracting the acceleration torque margin Tac and the cranking torque Tcr from the motor / generator rated torque is the excess of the acceleration torque margin Tac. It will only be made uselessly small.

Thus, when the drive torque Tdr becomes small, the state where the motor / generator 6 alone cannot be driven in the EV mode due to the torque shortage comes early (from the low vehicle speed), and the HEV mode in cooperation with the engine 1 It will be necessary to switch the mode to the driving at an early stage (from a low vehicle speed).
This means that the EV mode region intended to improve the fuel consumption rate is narrowed, resulting in a problem that the fuel consumption of the vehicle is deteriorated.

In addition to FIG. 4, this FIG. 4 shows the maximum motor output possible driving force as a driving force converted value of the motor output possible torque (rated torque) in FIG.
The driving force for EV travel obtained by subtracting the driving force corresponding to the cranking torque Tcr in FIG. 3 from this driving force capable of motor output (driving force converted value of the EV traveling torque Tev in FIG. 3) is indicated by a one-dot chain line. ,
The practical driving force for EV travel obtained by subtracting the driving force of acceleration torque margin Tac, which is the driving force conversion value of acceleration torque margin Tac in Fig. 3 from the driving force for EV driving (drive torque Tdr in Fig. 3) Drive force conversion value) is indicated by a two-dot chain line,
The required driving force during EV travel (the travel resistance described above) is indicated by a solid line.

  If the initial value (maximum value) of the acceleration torque margin Tac is continuously used over the entire operation range, the driving force based on the initial value (maximum value) of the acceleration torque margin Tac is shown in FIG. 4 when there is no acceleration request. The driving force that can be practically used during EV driving is reduced to the extent shown by the two-dot chain line in the figure.

Therefore, only when the vehicle speed VSP during EV travel reaches the relatively low VSP_s in FIG. 4, the practical driving force (two-dot chain line) during EV travel of the motor / generator 6 that can be used for EV travel is the required drive during EV travel. The power (solid line) is less than that, and the EV driving by the motor / generator 6 alone becomes impossible due to the insufficient driving torque of the motor / generator 6.
Therefore, when the vehicle speed VSP during EV traveling becomes VSP ≧ VSP_s, the mode must be switched to HEV traveling in cooperation with the engine 1, and the EV mode region for improving the fuel consumption rate is shown in FIG. <VSP_s becomes narrow and causes a problem that the fuel consumption of the vehicle deteriorates.

By the way, in this embodiment, when there is an acceleration request (step S11), the acceleration torque margin Tac is set to the above initial value (maximum value) (step S12).
If there is no acceleration request (step S11), the acceleration torque margin Tac is reduced to a value smaller by ΔTac than the initial value (maximum value), and the acceleration torque margin Tac becomes excessive with respect to the acceleration request. (Step S13),
If there is no acceleration request, the practical driving force during EV travel in FIG. 4 can be increased by the above-described decrease ΔTac of the acceleration torque margin Tac.

  Therefore, when there is no acceleration request, the vehicle driving speed VSP_s at which the practical driving force during EV traveling becomes less than the required driving force during EV traveling and the EV traveling by the motor / generator 6 alone becomes impossible due to the insufficient driving torque of the motor / generator 6. (EV → HEV mode switching vehicle speed) can be moved to a higher vehicle speed side than the vehicle speed value shown in Fig. 4, and fuel efficiency can be improved by expanding the EV mode region to improve the fuel consumption rate It is possible to solve the above-mentioned problem relating to the deterioration of fuel consumption.

Here, referring to FIG. 5, the adjustment range (control range) of the acceleration torque margin Tac from the initial value (maximum value) will be described based on the motor output base of the motor / generator 6. FIG.
In FIG. 5, the maximum motor output (rated output) that can be output by the motor / generator 6 is indicated by a broken line.
In addition, when the acceleration torque margin Tac is the initial value (maximum value), the motor output for EV traveling (including cranking torque Tcr) when the motor / generator 6 can be used for EV traveling is required. It is obtained by subtracting the motor output equivalent to the acceleration torque margin Tac (initial value: maximum value) when there is an acceleration request from the output (broken line), as shown by the two-dot chain line in the figure.

When there is no acceleration request (step S11), the acceleration torque margin Tac is reduced by ΔTac from the initial value (maximum value) (step S13).
In this case, the motor output for EV driving (including cranking torque Tcr) when there is no acceleration request of the motor / generator 6 that can be used for EV driving is the acceleration torque margin Tac after the decrease from the maximum motor output (broken line). This is obtained by subtracting the motor output conversion value (the motor output corresponding to the acceleration torque margin when no acceleration request is required), as shown by the one-dot chain line in FIG.

Therefore, the control range of the acceleration torque margin Tac is a range between the two-dot chain line and the one-dot chain line in FIG. 5 when illustrated on the motor output base of the motor / generator 6.
When there is no acceleration request, the motor output for EV traveling (including cranking torque Tcr) when there is no acceleration request of the motor / generator 6 that can be used for EV traveling is changed from the two-dot chain line level of FIG. 5 to the one-dot chain line level. The EV traveling upper limit vehicle speed is increased by the increase in the EV traveling motor output, and the mode switching to the HEV mode can be postponed.
As a result, the EV mode region intended to improve the fuel consumption rate can be further increased to a higher vehicle speed, and the fuel consumption of the vehicle can be improved as shown in FIG. 6 by the expansion of the EV mode region. .

<Effect of Example>
According to the electric travel control (acceleration torque margin control) of this embodiment described above,
If there is an acceleration request (step S11), the acceleration torque margin Tac is set to the initial value (maximum value) (step S12).
If there is no acceleration request (step S11), the acceleration torque margin Tac is reduced by ΔTac from the initial value (maximum value) so that the acceleration torque margin Tac does not become excessive with respect to the acceleration request. (Step S13),
When there is no acceleration request, the practical driving force during EV travel in FIG. 4 can be increased by the above-described decrease adjustment of the acceleration torque margin Tac.

  Therefore, when there is no acceleration request, the vehicle driving speed VSP_s at which the practical driving force during EV traveling becomes less than the required driving force during EV traveling and the EV traveling by the motor / generator 6 alone becomes impossible due to the insufficient driving torque of the motor / generator 6. (EV → HEV mode switching vehicle speed) can be moved to a higher vehicle speed than the vehicle speed value shown in Fig. 4 and the fuel efficiency can be improved by expanding the EV mode area. Can be eliminated.

Then, the adjustment lower limit value of the acceleration torque margin Tac is an acceleration torque margin for which the acceleration response to the accelerator operation can be a minimum response required in average driving (for example, a minimum acceleration of 0.01G can be generated). To do
When the acceleration torque margin Tac is adjusted to decrease when there is no acceleration request, the acceleration response to the accelerator operation is not excessively reduced, and the above effect can be achieved without giving the driver anxiety. .

Furthermore, when the acceleration torque margin Tac is decreased (ΔTac), the acceleration torque margin Tac is gradually decreased at a predetermined rate of change while gradually decreasing or continuously changing the acceleration torque margin Tac.
The increase in practical driving force during EV driving (see Fig. 4) due to the above decrease in acceleration torque margin Tac (ΔTac) can be gradually increased at the corresponding time change rate, and the shock when acceleration torque margin Tac decreases Can be reduced or eliminated.

1 engine
2FL, 2FR Front left and right wheels (drive wheels)
3RL, 3RR Left and right rear wheels
4 V belt type continuously variable transmission
6 Motor / Generator
7 First clutch
9 Second clutch
11 Hybrid 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
31 battery
32 Engine controller
33 Motor controller
34 Inverter
36 1st clutch controller
37 1st clutch engagement pressure control unit
38 Transmission controller
39 Second clutch engagement pressure control unit

Claims (13)

The engine, the first clutch, the motor / generator, the second clutch, and the driving wheel are arranged in the transmission path arrangement order, and the engagement / release control of the first clutch and the second clutch allows the motor / It is used for hybrid vehicles that can choose between electric driving with only the generator or hybrid driving with the cooperation of the engine and motor / generator,
In the electric travel control device in which the motor / generator drives the wheels while leaving at least a margin for an acceleration torque margin for realizing the acceleration request of the vehicle at the time of steady electric travel,
Acceleration request estimation means for estimating the presence or absence of the acceleration request;
An electric travel control apparatus for a hybrid vehicle, comprising: an acceleration torque margin adjustment means for reducing the acceleration torque margin when it is estimated that there is no acceleration request. In the electric travel control device of the hybrid vehicle according to claim 1,
The acceleration torque margin adjustment means sets the adjustment lower limit value for the acceleration torque margin to an acceleration torque margin such that the acceleration response to the accelerator operation can be a minimum response required in average driving. A feature of an electric travel control device for a hybrid vehicle. In the electric travel control device of the hybrid vehicle according to claim 1 or 2,
The electric travel control device for a hybrid vehicle, wherein the acceleration torque margin adjustment means gradually decreases the acceleration torque margin at a predetermined time change rate. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 3,
The electric travel control apparatus for a hybrid vehicle, wherein the acceleration request estimation means estimates that there is no acceleration request when there is no change in vehicle speed over a set time. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 4,
The electric travel control device for a hybrid vehicle, wherein the acceleration request estimation means estimates that the acceleration request does not exist when a vehicle speed increase not interlocked with an accelerator operation continues for a set time. In the electric travel control device of the hybrid vehicle according to claim 5,
The hybrid vehicle electric travel control device, wherein the acceleration torque margin adjustment means decreases the acceleration torque margin in accordance with a vehicle speed increase rate not linked to the accelerator operation and / or a brake operation force. . In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 6,
The acceleration request estimation means estimates that there is no acceleration request when a state in which the maximum vehicle speed during the past predetermined period is equal to or less than a predetermined value continues for a predetermined time or longer. Control device. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 7,
The electric travel control device for a hybrid vehicle, wherein the acceleration request estimation means estimates that the acceleration request is not present when an inter-vehicle distance from a forward traveling vehicle is equal to or less than a predetermined value. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 8,
The electric travel control of a hybrid vehicle, wherein the acceleration request estimation means estimates that there is no acceleration request when a difference between the own vehicle speed and speed regulation information on the navigation system is equal to or less than a predetermined value. apparatus. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 9,
The acceleration request estimating means estimates that there is no acceleration request when a state in which the steering amount during the past predetermined period is equal to or greater than the predetermined steering amount continues for a predetermined period or longer. Electric travel control device. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 10,
The electric travel control device for a hybrid vehicle, wherein the acceleration request estimation means estimates that there is no acceleration request when a fuel efficiency-oriented driving mode is selected. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 11,
The acceleration request estimating means estimates that there is no acceleration request when the host vehicle speed is low and the headlamp is lit in the automatic lighting mode. In the electric travel control device for a hybrid vehicle according to any one of claims 1 to 12,
The acceleration request estimation means estimates that there is no acceleration request when the acceleration request is not generated from a traveling environment including weather information and / or outside air temperature. Travel control device.

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