JP5115468B2 - Engine start / stop control device for hybrid vehicle - Google Patents

Description

The present invention is capable of traveling by power from a drive motor other than the engine, and is an electric travel (EV) mode in which the vehicle travels only by power from the drive motor, and a hybrid that travels by power from both the engine and the drive motor. For a hybrid vehicle having a running (HEV) mode,
Especially, mode switching (engine start and stop) between EV mode and HEV mode with engine start and stop can be appropriately performed without hunting even by repeatedly depressing and returning the accelerator pedal. The present invention relates to an engine start / stop control device for a hybrid vehicle.

  The hybrid drive device used in the hybrid vehicle as described above includes an engine and a drive motor as a power source, and the electric drive (EV) mode in which the vehicle is driven only by power from the drive motor while the engine is stopped, and the engine is started. And a hybrid travel (HEV) mode that travels by power from both the engine and the drive motor.

Therefore, the hybrid vehicle requires mode switching between the former EV mode and the latter HEV mode, and this mode switching requires engine start / stop control.
As this mode switching control (engine start / stop control) technique, a technique as described in Patent Document 1, for example, has been proposed.

  In other words, when the amount of change in accelerator opening per unit time (accelerator pedal depression speed) exceeds the set value, or when the vehicle speed exceeds the set vehicle speed, it is determined that the driver is requesting rapid acceleration. Is switched from the EV mode to the HEV mode, and travels with the power from both the engine and the drive motor.

At this time, in order to obtain a sufficient acceleration force, the accelerator speed setting value and the set vehicle speed used for the mode switching determination are set to be relatively small, and the HEV mode area is expanded, which makes it easy to switch from the EV mode to the HEV mode. Like that.
Japanese Patent Laid-Open No. 06-048190

However, in the above-described conventional engine start / stop control technology at the time of mode switching,
If the driver has a habit of frequently depressing and returning the accelerator pedal,
Mode switching between the EV mode and the HEV mode (engine start / stop) frequently occurs, and deterioration in drivability due to so-called control hunting is inevitable.

  In view of the above problems, the present invention does not cause deterioration of drivability due to control hunting because mode switching (engine start / stop) is frequently repeated even by repeatedly depressing and returning the accelerator pedal. An object of the present invention is to propose an engine start / stop control device for a hybrid vehicle.

For this purpose, the engine start / stop control device for a hybrid vehicle according to the present invention has the following configuration described in claim 1.
First, to explain the premise hybrid vehicle,
An electric travel mode including an engine and a drive motor as a power source , a clutch interposed between the engine and the drive motor, the clutch being released and the engine stopped, and traveling only with power from the drive motor; and the clutch And a hybrid travel mode in which the vehicle travels with power from both the engine and the drive motor in a state where the engine is started.

  The engine start / stop control device of the present invention is configured by providing such a hybrid vehicle with mode switching determination means, engine switching start means, mode switching cancellation means, and engine switching stop means as described below. It is.

The mode switching determination means determines a mode switching request between the hybrid travel mode and the electric travel mode based on a decrease / increase change that reaches the set value of the vehicle required load requested by the driver through the accelerator operation .
When the mode switching request is determined by the mode switching determining unit, the engine switching starting unit starts engine stop and start processing in response to the mode switching request.

The mode switching cancel means has an increase / decrease change in the return direction so as to reach the set value of the vehicle required load before the engine stop / start process started by the engine switching start means is completed, and the state of the clutch However, if there is an increase / decrease change in the return direction of the vehicle required load while the shock is not worsened by stopping the engine stop and start processing, the mode switching request is canceled.
When the mode switching request is canceled by the mode switching canceling means, the engine switching stopping means stops the engine stop / start process in response to the mode switching request.

According to the engine start / stop control device for a hybrid vehicle according to the present invention described above,
When a mode switching request between the hybrid driving mode and the electric driving mode is determined due to a decrease / increase change that reaches the set value of the vehicle required load requested by the accelerator operation by the driver, the engine corresponding to the mode switching request Stop and start the process,
Before the engine stop / start process is started, there is an increase / decrease change in the return direction so as to reach the set value of the vehicle required load, and the state of the clutch is the engine stop / stop process stop. If there is a change in the return direction of the vehicle required load while the shock is not exacerbated, the mode switching request is canceled and the engine is stopped and started in response to the mode switching request. Since the processing is stopped, the following effects can be obtained.

That is, even if there is a change in the return direction of the vehicle required load, conventionally, because of the presence of hysteresis, the engine stop and start processing in response to the mode switching request is continued.
When the accelerator operation is performed such that the required vehicle load changes in the return direction after the mode switching (engine stop and start processing) is completed, the reverse mode switching (engine reverse switching) occurs. End up.
Therefore, when the accelerator pedal is depressed and returned frequently, mode switching (engine start / stop) frequently occurs, and deterioration of shock due to control hunting cannot be avoided.

By the way, according to the present invention, when there is a change in the return direction of the vehicle required load as described above, the corresponding mode switching (engine stop, engine stop, (Startup process) is not completed,
Even if the accelerator pedal is depressed and returned frequently, mode switching (engine start / stop) does not occur frequently, and the deterioration of shock due to control hunting can be avoided.
Moreover, if there is a change in the return direction of the vehicle request load that is a condition for stopping the engine and stopping the engine in response to the mode switching request, the cancellation is not necessarily performed, but the state of the clutch is The engine is stopped and the start process is stopped when there is a change in the return direction of the vehicle demand load in the return direction while the shock is not worsened by stopping the engine and starting process. The situation where the shock is exacerbated by this cancellation can be avoided.

  Hereinafter, embodiments of the present invention will be described in detail based on first to fourth embodiments shown in the drawings.

[Hybrid vehicle to which the present invention is applicable]
FIG. 1 illustrates a power train of a hybrid vehicle to which the engine start / stop control device of the present invention can be applied,
This hybrid vehicle is based on a front engine and rear wheel drive vehicle (rear wheel drive vehicle), and is a hybrid of this.
Reference numeral 1 denotes an engine as a first power source, and reference numeral 2 denotes a drive wheel (rear wheel).

In the hybrid vehicle power train shown in FIG. 1, the automatic transmission 3 is arranged in tandem at the rear of the engine 1 in the vehicle front-rear direction in the same manner as a normal rear wheel drive vehicle.
A motor / generator 5 is provided in combination with a shaft 4 that transmits rotation from the engine 1 (crankshaft 1a) to the input shaft 3a of the automatic transmission 3.
This motor / generator 5 is provided as a second power source.

The motor / generator 5 functions as a drive motor (electric motor) or a generator (generator), and is disposed between the engine 1 and the automatic transmission 3.
The first clutch 6 can be inserted between the motor / generator 5 and the engine 1, more specifically, between the shaft 4 and the engine crankshaft 1a, and the engine 1 and the motor / generator 5 can be disconnected by the first clutch 6. To join.
Here, the first clutch 6 is capable of changing the transmission torque capacity continuously or stepwise, for example, by controlling the clutch hydraulic oil flow rate and the clutch hydraulic pressure with a proportional solenoid continuously or stepwise, for example, Is constructed with a wet multi-plate clutch that can be changed.

A second clutch 7 is inserted between the motor / generator 5 and the driving wheel (rear wheel) 2, and the motor / generator 5 and the driving wheel (rear wheel) 2 are detachably coupled by the second clutch 7.
Similarly to the first clutch 6, the second clutch 7 can change the transmission torque capacity continuously or stepwise. For example, the proportional hydraulic solenoid controls the clutch hydraulic fluid flow rate and the clutch hydraulic pressure continuously or stepwise. And a wet multi-plate clutch whose transmission torque capacity can be changed.

The automatic transmission 3 may be any known one, and by selectively engaging or releasing a plurality of speed change friction elements (clutch, brake, etc.), a transmission system is obtained by a combination of engagement and release of these speed change friction elements. It is assumed that the road (speed stage) is determined.
Therefore, the automatic transmission 3 shifts the rotation from the input shaft 3a at a gear ratio corresponding to the selected shift speed and outputs it to the output shaft 3b.
This output rotation is distributed and transmitted to the left and right rear wheels 2 by the differential gear device 8 and used for traveling of the vehicle.
However, it goes without saying that the automatic transmission 3 is not limited to the stepped type as described above, and may be a continuously variable transmission.

By the way, in FIG. 1, a dedicated clutch friction element existing in the automatic transmission 3 is used instead of newly establishing a dedicated second clutch 7 for detachably coupling the motor / generator 5 and the drive wheel 2.
In this case, the second clutch 7 performs the above-described shift speed selection function (shift function) when engaged, so that the automatic transmission 3 is in a power transmission state, and in addition, the first clutch 6 is released and engaged, A mode selection function to be described later can be achieved, and a dedicated second clutch is unnecessary, which is very advantageous in terms of cost.

  However, a dedicated second clutch 7 may be newly provided. In this case, the second clutch 7 may be provided between the input shaft 3a of the automatic transmission 3 and the motor / generator shaft 4, or the automatic transmission 3 Provided between the output shaft 3b and the rear wheel drive system.

In the power train of the hybrid vehicle shown in FIG.
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 6 is released, and the automatic transmission 3 is brought into a power transmission state by the engagement of the second clutch 7.
The second clutch 7 is a shift friction element to be engaged at the current shift stage among the shift friction elements in the automatic transmission 3, and is different for each selected shift stage.

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

When hybrid driving (HEV driving) mode used for high speed driving or heavy load driving is required,
By engaging the second clutch 7, the first clutch 6 is also engaged while the automatic transmission 3 is kept in the corresponding gear selection state (power transmission state).
In this state, both the output rotation from the engine 1 and the output rotation from the motor / generator 5 reach the transmission input shaft 3a, and the automatic transmission 3 changes the rotation to the input shaft 3a to the selected shift speed. The speed is changed according to the speed and output from the transmission output shaft 3b.
The rotation from the transmission output shaft 3b then reaches the rear wheel 2 via the differential gear device 8, and the vehicle can be hybrid-driven (HEV-driven) by both the engine 1 and the motor / generator 5.

During such HEV traveling, when the engine 1 is operated at the optimum fuel consumption, the energy becomes surplus,
By operating the motor / generator 5 as a generator with this surplus energy, surplus energy is converted into electric power,
By storing this generated power to be used for driving the motor of the motor / generator 5, the fuel consumption of the engine 1 can be improved.

The engine 1, the motor / generator 5, the first clutch 6, and the second clutch 7 constituting the power train of the hybrid vehicle shown in FIG. 1 are controlled by a system as shown in FIG.
The control system of FIG. 2 includes an integrated controller 20 that controls the operating point of the power train in an integrated manner.
The operating points of the power train are the target engine torque tTe, the target motor / generator torque tTm (may be the target motor / generator rotation speed tNm), the target transmission torque capacity tTc1 of the first clutch 6, and the target of the second clutch 7. It is defined by the transmission torque capacity tTc2.

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

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

The integrated controller 20 includes the accelerator opening APO, the battery storage state SOC, and the transmission output speed No (vehicle speed VSP) among the above input information.
While selecting the driving mode (EV mode, HEV mode) that can realize the driving force of the vehicle desired by the driver,
A target engine torque tTe, a target motor / generator torque tTm (may be a target motor / generator rotation speed tNm), a target first clutch transmission torque capacity tTc1, and a target second clutch transmission torque capacity tTc2 are calculated.
The target engine torque tTe is supplied to the engine controller 21, and the target motor / generator torque tTm (which may be the target motor / generator rotation speed tNm) is supplied to the motor / generator controller 22.

The engine controller 21 controls the engine 1 so that the engine torque Te becomes the target engine torque tTe.
The motor / generator controller 22 is connected to the motor / generator 5 via the battery 9 and the inverter 10 so that the torque Tm (or rotational speed Nm) of the motor / generator 5 becomes the target motor / generator torque tTm (or target motor / generator rotational speed tNm). The generator 5 is controlled.
The integrated controller 20 supplies a solenoid current corresponding to the target first clutch transmission torque capacity tTc1 and the target second clutch transmission torque capacity tTc2 to an engagement control solenoid (not shown) of the first clutch 6 and the second clutch 7, The first clutch 6 and the first clutch 6 so that the transmission torque capacity Tc1 of the first clutch 6 matches the target transmission torque capacity tTc1, and the transmission torque capacity Tc2 of the second clutch 7 matches the target second clutch transmission torque capacity tTc2. The second clutch 7 is individually controlled for engaging force.

  The integrated controller 20 selects the above-described operation mode (EV mode, HEV mode), the target engine torque tTe, the target motor / generator torque tTm (may be the target motor / generator speed tNm), the target first clutch transmission torque capacity Calculation of tTc1 and target second clutch transmission torque capacity tTc2 is executed as shown in the functional block diagram of FIG.

The target driving force calculation unit 30 calculates the target driving force tFo of the vehicle from the accelerator opening APO and the vehicle speed VSP using the target driving force map shown in FIG.
The operation mode selection unit 40 determines a target operation mode from the accelerator opening APO and the vehicle speed VSP using the EV-HEV region map shown in FIG.
As is clear from the EV-HEV area map shown in Fig. 5, select HEV mode at high load and high vehicle speed, select EV mode at low load and low vehicle speed,
When the driving point determined by the combination of accelerator opening APO and vehicle speed VSP during EV travel exceeds the EV → HEV switching line and enters the HEV region, the mode is switched from EV mode to HEV mode with engine start,
In addition, when the operating point exceeds the HEV → EV switching line and enters the EV region during HEV traveling, the mode switching from the HEV mode to the EV mode accompanied by engine stop and engine disconnection is performed.

3 calculates a target charge / discharge amount (power) tP from the battery state of charge SOC using the charge / discharge amount map shown in FIG.
In the operating point command unit 60, from the accelerator opening APO, the target driving force tFo, the target operation mode, the vehicle speed VSP, and the target charge / discharge power tP, these are set as the operating point reaching target, and are transient every moment. A target engine torque tTe, a target motor / generator torque tTm, a target solenoid current Is1 corresponding to a target transmission torque capacity tTc1 of the first clutch 6, a target transmission torque capacity tTc2 of the second clutch 7, a target shift stage SHIFT, Is calculated.
Also, calculate the output required to increase the engine torque from the current operating point to the best fuel consumption line shown in Fig. 7, compare this with the target charge / discharge amount (electric power) tP, and request the smaller output As an output, it is added to the engine output.

In the shift control unit 70, the target second clutch transmission torque capacity tTc2 and the target shift stage SHIFT are input, and the automatic transmission 3 is set so that the target second clutch transmission torque capacity tTc2 and the target shift stage SHIFT are achieved. Drive the corresponding solenoid valve in the.
As a result, the automatic transmission 3 in FIG. 1 enters the power transmission state in which the target gear stage SHIFT is selected while the second clutch 7 is engaged and controlled to achieve the target second clutch transmission torque capacity tTc2.

[Engine start / stop control of the first embodiment]
In this embodiment, the operating point command unit 60 performs engine start / stop control by executing the control program shown in FIG.
In the engine start / stop control program of FIG. 8, first, in step S11, it is checked whether or not the EV mode is currently selected.
If the EV mode is not selected (if the HEV mode is selected), the control is terminated as it is, and the engine start / stop control of FIG. 8 is not performed.

If it is determined in step S11 that the EV mode is being selected, it is determined in step S12 whether or not the accelerator opening APO has become equal to or greater than the engine start line (EV → HEV mode switching line) corresponding to the solid line in FIG.
That is, in step S12, as a result of the operation of increasing the accelerator opening APO (increasing the required vehicle load by depressing the accelerator pedal) such that the driving point changes from point A1 to point A2 in FIG. It is determined whether or not there has been a mode change request (engine start request during acceleration) to HEV mode accompanying engine start.
Therefore, step S12 corresponds to the mode switching determination means in the present invention.

While it is not determined in step S12 that the accelerator opening APO has exceeded the engine start line (EV → HEV mode switching line) equivalent value, that is, while the operating point is still in the EV mode region, the control is terminated as it is. 8 engine start / stop control is not performed.
When it is determined in step S12 that the accelerator opening APO has exceeded the value corresponding to the engine start line (EV → HEV mode switching line), that is, a mode switching request from the EV mode to the HEV mode accompanied by the engine start (engine start during acceleration) When it is determined that there is a request), the control proceeds to step S13 and subsequent steps, and the following engine start / stop control is performed.

In step S13, an engine start request is issued in response to the EV → HEV mode switching request in step S12, thereby starting the engine start process in step S14.
Therefore, step S14 corresponds to engine switching start means in the present invention.

Here, the engine start process is the following process.
When the accelerator opening APO is equal to or greater than the engine start line equivalent value in FIG. 5 in the EV mode, first, the transmission torque capacity tTc2 of the second clutch 7 is made to correspond to the transmission output shaft torque immediately before the engine start request. After that, the driving force of the motor / generator 5 is increased.
At this time, the load acting on the motor / generator 5 has an upper limit corresponding to the transmission torque capacity tTc2 of the second clutch 7, and a load exceeding this value does not act on the motor / generator 5.
The motor / generator 5 increases the rotational speed Nm while slipping the second clutch 7 due to the increase in the driving force.
Next, since the slip of the second clutch 7 and the increase in the motor / generator rotational speed Nm are expected to be completed, the transfer torque capacity tTc1 of the released first clutch 6 is increased to a predetermined value by increasing the first clutch 6 is fastened and engine 1 is cranked.
As a result, the engine 1 completes its explosion, reaches the speed at which it can operate independently, and when the first clutch 6 has no front-rear rotational difference (difference between the engine rotational speed Ne and the motor / generator rotational speed Nm), the first clutch 6 is completely engaged and the transmission torque capacity tTc2 of the second clutch 7 is increased and returned to the original value, and the EV → HEV mode switching (engine start) processing is completed.

After starting the engine start process in step S14, the timer TM1 starts counting in step S15, and an elapsed time (engine start process execution time) after the engine start process is started by the timer TM1. measure.
In step S16, it is checked whether or not the measurement time of the timer TM1 (engine start processing execution time) is before the set time T1.
Here, the set time T1 is set to a time that does not cause a problem shock or the like, that is, does not deteriorate the drivability even if the engine start process described above is stopped.

While it is determined in step S16 that TM1 <T1 (operability does not deteriorate even if engine start processing is stopped), in step S17, the accelerator opening APO is less than the value corresponding to the engine start line (EV → HEV mode switching line). It is determined whether or not.
That is, in step S17, an operation of decreasing the accelerator opening APO (decreasing the required vehicle load by depressing the accelerator pedal) is performed such that the driving point changes from point A2 to point A3 or A1 in FIG. As a result, it is determined whether or not there is a transition from the HEV mode area to the hysteresis area between the engine start line (EV → HEV mode switching line) and the engine stop line (HEV → EV mode switching line), or to the EV mode area.

When it is determined in step S17 that the accelerator opening APO has become less than the value corresponding to the engine start line (EV → HEV mode switching line) (the operating point changes from point A2 in FIG. 5, for example, to point A3 or A1) When there is an accelerator return)
In step S18, a command for canceling the engine start process (EV → HEV mode switching request) started in step S14 is issued, the EV → HEV mode switching is stopped, and the engine start process is stopped.
Therefore, step S18 corresponds to the mode switching canceling means and the engine switching stopping means in the present invention.

  In the next step S19, it is checked whether or not the EV → HEV mode switching stop processing (stop of engine start processing) is completed. When this completion is confirmed, the timer TM1 is set next time in step S20. In preparation for this control, it is reset to 0.

After deciding in step S16 that TM1 ≧ T1 (drivability deteriorates when engine start processing is stopped),
While it is determined in step S17 that the accelerator opening APO has not decreased to the engine start line (EV → HEV mode switching line) equivalent value (the operating point remains in the HEV region)
In step S21, the engine start process (EV → HEV mode switching request) started in step S14 is continued.
In step S22, it is checked whether or not the engine start by the continuation of the engine start process in step S21 is completed. When this completion is confirmed, in step S23, the timer TM1 is prepared for the next control, and 0 Reset to.

[Operational effects of engine start / stop control of the first embodiment]
The operational effects of the engine start / stop control according to this embodiment will be described below based on the time chart of FIG.
As indicated by the one-dot chain line C1 in FIG. 9, the accelerator opening APO (vehicle required load) is increased or decreased as shown in the figure, so that the accelerator opening APO changes the engine start line (EV → HEV mode switching line) at the instant t1. The accelerator opening APO decreases while passing through the engine start line (EV → HEV mode switching line) at an instant t2, and then the accelerator opening APO is reduced to the engine start line (EV → HEV mode switching line) and The case where the value is maintained in the hysteresis region between the engine stop line (HEV → EV mode switching line) is described.
At the instant t1 when the accelerator opening APO increases while passing through the engine start line (EV → HEV mode switching line), the engine start process is started by an EV → HEV mode switching request as shown in the bottom row of FIG. S14).

However, the accelerator opening APO is at the engine start line (EV → HEV mode switching line) at the instant t2 between the start of the engine start process at step S14 and the instant t3 when the set time T1 (step S16) elapses. (Step S17),
The engine start process started in step S14 at the instant t1 is canceled at the instant t2 as shown in the lowermost stage of FIG. 9 (step S18).

By the way, in general, cancellation of the engine start process is commanded when the accelerator opening APO passes through the engine stop line (HEV → EV mode switching line) and decreases.
Even if the accelerator opening APO decreases while passing through the engine start line (EV → HEV mode switching line), the engine start process started in step S14 at the instant t1 is continued as it is, and the EV → HEV mode with engine start is continued. It is normal to complete the switch.

However, in this case, when the accelerator operation is performed to reduce the accelerator opening APO again after the EV → HEV mode switching (engine start) is finished, the reverse HEV → EV mode switching occurs. .
Therefore, when the accelerator pedal is frequently depressed and returned,
Mode switching (engine start / stop) frequently occurs, and operability deterioration due to control hunting cannot be avoided.

By the way, according to the present embodiment, as described above, the accelerator opening APO is set to the engine start line (EV → EV) from the start of the engine start process in step S14 to the instant t3 when the set time T1 (step S16) elapses. If it drops while passing through the HEV mode switching line (step S17, instant t2 in FIG. 9),
In order to cancel and cancel the engine start process started in step S14 at the instant t1 (step S18), the hunting of the control is also performed by the above accelerator operation without completing the EV → HEV mode switching accompanying the engine start. It does not occur, and the above-mentioned problem relating to the deterioration of drivability can be avoided.

  In order to solve this problem, as shown in the middle part of FIG. 9, during the engine start necessity determination period from the instant t1 to the instant t4 when a predetermined time elapses, the accelerator opening APO is set to the engine start line (EV → HEV It is conceivable to check the frequency of passing the mode switching line), determine whether or not to start the engine based on this frequency, and start the engine start process at the instant t4 if engine start is necessary.

However, in this case, the engine start process is not started unless it is the instant t4 when the engine start necessity determination period has elapsed from the instant t1, and it is necessary to lengthen the engine start necessity determination period to some extent to prevent hunting. Together with
A considerable time is required until the EV → HEV mode switching accompanied by the engine start is completed, resulting in a problem that the responsiveness of the engine start (EV → HEV mode switching) is deteriorated.

In particular, as shown by the solid line C2 in FIG. 9, the accelerator opening APO (vehicle required load) is increased as shown in the figure, so that the accelerator opening APO is instantaneously at the engine start line (EV → HEV mode switching line). If the accelerator operation is performed to keep the accelerator opening APO larger than the engine start line (EV → HEV mode switching line) equivalent value,
Despite demanding a high engine start (EV → HEV mode switching) response from the viewpoint of acceleration performance, the engine start process (EV → HEV mode switching) is completed unless the instant t4 is reached. This is when the time required for the engine start processing has passed with a further delay, and the problem relating to the deterioration of the responsiveness becomes remarkable.

By the way, according to the present embodiment, at the instant t1 when the accelerator opening APO increases while passing through the engine start line (EV → HEV mode switching line), the engine in response to the EV → HEV mode switching request as shown in the lowest stage of FIG. Because the startup process is started,
From this instant t1, when the engine start processing time has elapsed, EV → HEV mode switching with engine start has been completed,
The high engine start (EV → HEV mode switching) response required during the accelerator operation indicated by the solid line C2 in FIG. 9 can be sufficiently met.

On the other hand, as described above, the accelerator operation indicated by the one-dot chain line C1 in FIG. 9 is started at the instant t1 at the instant t2 when the accelerator opening APO decreases while passing through the engine start line (EV → HEV mode switching line). In order to cancel and stop the engine start process as shown in the bottom row of FIG.
Control hunting can be prevented, and thus it is possible to avoid deterioration of fuel consumption due to repeated start / stop of the engine.

[Engine start / stop control of the second embodiment]
In this embodiment, the operating point command unit 60 of FIG. 3 performs engine start / stop control by executing the control program shown in FIG.
The engine start / stop control program in FIG. 10 has the same steps S11 to S14, step S17, step S18, and step S21 as in FIG.
Step S31 is provided instead of Step S15 and Step S16 in FIG. 8, Step S32 is provided instead of Step S19 and Step S20 in FIG. 8, and Step S22 and Step S23 in FIG. 8 are deleted.

When it is determined in step S11 that the EV mode is being selected, and it is determined in step S12 that the accelerator opening APO is equal to or greater than the engine start line (EV → HEV mode switching line) corresponding to the solid line in FIG.
In other words, when there is a mode switching request from the EV mode to the HEV mode that accompanies engine start (acceleration engine start request)
In step S13, an engine start request is issued in response to the EV → HEV mode switching request in step S12, and the engine start process is started in step S14 as in the first embodiment (FIG. 8). .

However, in the next step S31, it is determined whether or not the engine start process started in step S14 as described above can be canceled and stopped.
In this determination, the degree of progress of engagement of the first clutch 6 and the slip state of the second clutch 7 during the engine starting process are
Even when the engine start process is canceled due to the cancellation of the mode switching request, no shock is generated and the drivability is not deteriorated (for example, even if the second clutch 7 is immediately engaged, the shock is generated. In a slip state where the first clutch 6 is less than the transmission torque capacity that overcomes engine friction)
It is determined that the engine start process may be canceled.

  While it is determined in step S31 that the engine start process may be canceled, in step S17, it is determined whether or not the accelerator opening APO has become less than the engine start line (EV → HEV mode switching line) equivalent value. It is determined whether or not there is a transition from the HEV mode area to the hysteresis area between the engine start line (EV → HEV mode switching line) and the engine stop line (HEV → EV mode switching line), or to the EV mode area.

When it is determined in step S31 and step S17 that the accelerator opening APO has become less than the engine start line (EV → HEV mode switching line) equivalent during the engine start process cancelable period,
In step S18, a command to cancel the engine start processing (EV → HEV mode switching request) is issued,
In the next step S32, the EV → HEV mode switching is stopped and the engine start process is stopped.

In step S31, it is determined that the engine start process is not canceled and stopped (it is determined that if the engine start process is stopped, a shock is generated or the drivability is adversely affected),
While it is determined in step S17 that the accelerator opening APO has not decreased to the engine start line (EV → HEV mode switching line) equivalent value (the operating point remains in the HEV region)
In step S21, the engine start process (EV → HEV mode switching request) started in step S14 is continued.

[Operational effects of engine start / stop control of the second embodiment]
Even in the engine start / stop control according to the above-described embodiment, even if the engine start process is stopped, no shock is generated and the drivability is not deteriorated. During the period corresponding to the instant t1 to t3 in FIG. (Step S31), when the accelerator opening APO decreases while passing through the engine start line (EV → HEV mode switching line) (step S17, instant t2 in FIG. 9),
Since the engine start process started at step S14 at the instant t1 is canceled at the instant t2 (step S18 and step S32),
The same effect as the first embodiment described above can be achieved.

In the second embodiment, when the engine start process is canceled, a shock occurs, for example, when the drivability is adversely affected (step S31).
Even if the accelerator opening APO decreases while passing through the engine start line (EV → HEV mode switching line) (step S17),
Since the engine start process is not canceled by continuing the engine start process in step S21,
By canceling the engine start process, it is possible to reliably avoid adverse effects on drivability such as a shock.

[Engine start / stop control of third embodiment]
In this embodiment, the operating point command unit 60 of FIG. 3 performs engine start / stop control by executing the control program shown in FIG.
In the engine start / stop control program of FIG. 11, first, in step S41, it is checked whether or not the HEV mode is currently selected.
If the HEV mode is not selected (if the EV mode is selected), the control is terminated as it is, and the engine start / stop control of FIG. 11 is not performed.

When it is determined in step S41 that the HEV mode is being selected, it is determined in step S42 whether or not the accelerator opening APO has become less than an engine stop line (HEV → EV mode switching line) equivalent value indicated by a broken line in FIG.
That is, in step S42, as a result of the operation of lowering the accelerator opening APO (reducing the required vehicle load by depressing the accelerator pedal) such that the operating point changes from the B1 point to the B2 point in FIG. It is determined whether or not there has been a mode switching request (engine stop request during deceleration) from the mode to the EV mode accompanied by engine stop.
Therefore, step S42 corresponds to the mode switching determination means in the present invention.

While it is not determined in step S42 that the accelerator opening APO has become less than the value equivalent to the engine stop line (HEV → EV mode switching line), that is, while the operating point is still in the HEV mode region, the control is terminated as it is. 11 engine start / stop control is not performed.
When it is determined in step S42 that the accelerator opening APO has become less than the value equivalent to the engine stop line (HEV → EV mode switching line), that is, a mode switching request from the HEV mode to the EV mode accompanied by the engine stop (engine stop during deceleration) When it is determined that there is a request), the control proceeds to step S43 and subsequent steps, and the following engine start / stop control is performed.

In step S43, an engine stop request is issued in response to the HEV → EV mode switching request in step S42, thereby starting the engine stop process in step S44.
Therefore, step S44 corresponds to engine switching start means in the present invention.

Here, the engine stop process is the following process.
When the accelerator opening APO decreases in the HEV mode after passing through the value corresponding to the engine stop line shown in FIG. 5, first, the transmission torque capacity tTc1 is decreased so as to release the first clutch 6, and the engine torque tTe is reduced to 0. When the motor / generator torque tTm is decreased and the front / rear rotational difference of the first clutch 6 (the difference between the motor / generator rotational speed Nm and the engine rotational speed Ne) becomes sufficiently large, the engine 1 is cut by fuel cut. Stop and finish the HEV → EV mode switching (engine stop) process.

After the engine stop process is started in step S44, the timer TM2 starts counting in step S45, and the elapsed time (engine stop process execution time) from the start of the engine start process is determined by the timer TM2. measure.
In step S46, it is checked whether or not the measurement time of the timer TM2 (engine stop processing execution time) is before the set time T2.
Here, the set time T2 is set to a time that does not cause a problem shock or the like, that is, does not deteriorate the drivability even if the engine stop process is stopped.

While it is determined in step S46 that TM2 <T2 (the drivability does not deteriorate even if engine stop processing is stopped), in step S47, the accelerator opening APO is equal to or greater than the engine stop line (HEV → EV mode switching line) equivalent value. It is determined whether or not.
That is, in step S47, the result of an operation of increasing the accelerator opening APO (increasing the required vehicle load by depressing the accelerator pedal) is performed such that the driving point changes from point B2 to point B3 or B1 in FIG. Then, it is determined whether or not there is a transition from the EV mode region to the hysteresis region between the engine start line (EV → HEV mode switching line) and the engine stop line (HEV → EV mode switching line), or the HEV mode region.

When it is determined in step S47 that the accelerator opening APO has become equal to or greater than the value equivalent to the engine stop line (HEV → EV mode switching line) (for example, the operating point changes from point B2 in FIG. 5 to point B3 or B1) When the accelerator is depressed)
In step S48, a command for canceling the engine stop process (HEV → EV mode switching request) started in step S44 is issued, the HEV → EV mode switching is stopped, and the engine stop process is stopped.
Therefore, step S48 corresponds to the mode switching canceling means and the engine switching stopping means in the present invention.

  In the next step S49, it is checked whether or not the HEV → EV mode switching stop processing (stop of the engine stop processing) is completed. When this completion is confirmed, the timer TM2 is set next time in step S50. In preparation for this control, it is reset to 0.

After deciding in step S46 that TM2 ≧ T2 (the drivability deteriorates when the engine stop process is stopped)
While it is determined in step S47 that the accelerator opening APO has not increased to the value equivalent to the engine stop line (HEV → EV mode switching line) (the operating point remains in the EV region)
In step S51, the engine stop process (HEV → EV mode switching request) started in step S44 is continued.
In step S52, it is checked whether or not the release of the first clutch 6 by the continuation of the engine stop process in step S51 is completed. When this completion is confirmed, the timer TM2 is controlled next time in step S53. In preparation for this, it is reset to 0.

[Effects of engine start / stop control of third embodiment]
The operational effects of the engine start / stop control according to this embodiment will be described below based on the time chart of FIG.
As shown by the one-dot chain line C3 in FIG. 9, the accelerator opening APO (vehicle required load) is increased or decreased as shown in the figure, so that the accelerator opening APO becomes the engine stop line (HEV → EV mode switching line) at the instant t1. Decreasing while passing, accelerator opening APO increases while passing engine stop line (HEV → EV mode switching line) at instant t2, and then accelerator opening APO reaches engine start line (EV → HEV mode switching line) The case of further increase while passing,
At the instant t1 when the accelerator opening APO decreases while passing through the engine stop line (HEV → EV mode switching line), the engine stop process is started by a HEV → EV mode switching request as shown in the bottom row of FIG. S44).

However, at the instant t2 between the start of the engine stop process in step S44 and the instant t3 when the set time T2 (step S46) elapses, the accelerator opening APO is the engine stop line (HEV → EV mode switching line). (Step S47),
The engine stop process started at step S44 at the instant t1 is canceled at the instant t2 as shown in the lowermost stage of FIG. 12 (step S48).

By the way, in general, the cancellation of the engine stop process is commanded at an instant t5 when the accelerator opening APO increases through the engine start line (EV → HEV mode switching line),
Even if the accelerator opening APO increases while passing the engine stop line (HEV → EV mode switching line), the engine stop process started in step S44 at the instant t1 is continued as it is, and the HEV → EV mode with engine stop is continued. It is normal to complete the switch.

However, in this case, when the accelerator operation is performed to increase the accelerator opening APO again after the HEV → EV mode switching (engine stop) is finished, the reverse EV → HEV mode switching occurs. .
Therefore, when the accelerator pedal is frequently depressed and returned,
Mode switching (engine start / stop) frequently occurs, and operability deterioration due to control hunting cannot be avoided.

By the way, according to the present embodiment, as described above, the accelerator opening APO is reduced from the start of the engine stop process in step S44 to the instant t3 when the set time T2 (step S46) elapses. If it increases while passing through the EV mode switching line (step S47, instant t2 in FIG. 12),
In order to cancel and stop the engine stop process started in step S44 at the instant t1 (step S48), the HEV → EV mode switching accompanied by the engine stop is not completed, and control hunting is also performed by the accelerator operation described above. It does not occur, and the above-mentioned problem relating to the deterioration of drivability can be avoided.

  In order to solve this problem, as shown in the middle part of FIG. 12, the accelerator opening APO is set to the engine stop line (HEV → EV during the engine stop necessity determination period from the instant t1 to the instant t4 when a predetermined time elapses. It is conceivable to check the frequency of passing the mode switching line), determine whether or not to stop the engine based on this frequency, and start the engine stop process at the instant t4 if the engine needs to be stopped.

However, in this case, the engine stop process is not started unless it is the instant t4 when the engine stop necessity determination period has elapsed from the instant t1, and the engine stop necessity determination period needs to be increased to some extent to prevent hunting. Together with
A considerable amount of time is required until the HEV → EV mode switching accompanied by the engine stop is completed, resulting in a problem that the response of the engine stop (HEV → EV mode switching) is deteriorated.

In particular, as shown by the solid line C4 in FIG. 12, the accelerator opening APO (vehicle required load) is reduced as shown in the figure, so that the accelerator opening APO is instantaneously at the engine stop line (HEV → EV mode switching line). If the accelerator operation is performed to keep the accelerator opening APO smaller than the value equivalent to the engine stop line (HEV → EV mode switching line),
Despite demanding a high engine stop (HEV → EV mode switching) response from the viewpoint of improving fuel efficiency, the engine stop process is not started unless the moment is t4, and the engine stop (HEV → EV mode switching) is completed. This is when the time required for the engine start processing has passed with a further delay, and the problem relating to the deterioration of the responsiveness becomes remarkable.

By the way, according to the present embodiment, at the instant t1 when the accelerator opening APO decreases while passing through the engine stop line (HEV → EV mode switching line), the engine in response to the HEV → EV mode switching request as shown in the lowest stage of FIG. Because the stop process is started,
When the time required for engine stop processing has elapsed from this instant t1, the HEV → EV mode switching with engine stop has been completed,
The high engine stop (HEV → EV mode switching) response required during the accelerator operation indicated by the solid line C4 in FIG. 12 can be sufficiently met.

On the other hand, at the time of the accelerator operation indicated by the one-dot chain line C3 in FIG. 12, as described above, the accelerator opening APO is started at the instant t1 which increases while passing through the engine stop line (HEV → EV mode switching line). In order to cancel and stop the engine stop process as shown in the bottom row of FIG.
Control hunting can be prevented, and thus it is possible to avoid deterioration of fuel consumption due to repeated start / stop of the engine.

[Engine start / stop control of the fourth embodiment]
In this embodiment, the operating point command unit 60 of FIG. 3 performs engine start / stop control by executing the control program shown in FIG.
The engine start / stop control program of FIG. 13 has the same steps S41 to S44, step S47, step S48, and step S51 as in FIG.
Step S61 is provided in place of step S45 and step S46 in FIG. 11, step S62 is provided in place of step S49 and step S50 in FIG. 11, and step S52 and step S53 in FIG. 11 are deleted.

When it is determined in step S41 that the HEV mode is being selected, and it is determined in step S42 that the accelerator opening APO has become less than the value corresponding to the engine stop line (HEV → EV mode switching line) indicated by a broken line in FIG.
In other words, when there is a mode switching request from HEV mode to EV mode with engine stop (deceleration engine stop request)
In step S43, the engine stop request is issued in response to the HEV → EV mode switching request in step S42, and the engine stop process is started in step S44 in the same manner as in the third embodiment (FIG. 11). .

However, in the next step S61, it is determined whether or not the engine stop process started in step S44 can be canceled and stopped as described above.
In this determination, the degree of disengagement of the first clutch 6 and the engine torque during the engine stop process are
Even when the engine stop process is canceled due to the cancellation of the mode switching request, no shock is generated and the drivability is not deteriorated (for example, transmission in which the engine torque is 0 and the first clutch 6 starts slipping). Torque capacity)
It is determined that the engine stop process may be canceled.

  While it is determined in step S61 that the engine stop process may be canceled, in step S47, it is determined whether or not the accelerator opening APO has become equal to or greater than the engine stop line (HEV → EV mode switching line). It is determined whether or not there is a transition from the EV mode area to the hysteresis area between the engine start line (EV → HEV mode switching line) and the engine stop line (HEV → EV mode switching line), or to the HEV mode area.

When it is determined in step S61 and step S47 that the accelerator opening APO is equal to or greater than the engine stop line (HEV → EV mode switching line) during the engine stop process cancelable period,
In step S48, a command to cancel the engine stop process (HEV → EV mode switching request) is issued,
In the next step S62, the HEV → EV mode switching is stopped and the engine stop process is stopped.

In step S61, it is determined that the engine stop process is not canceled and stopped (it is determined that if the engine stop process is stopped, a shock is generated or the drivability is adversely affected),
While it is determined in step S47 that the accelerator opening APO has not increased to the value equivalent to the engine stop line (HEV → EV mode switching line) (the operating point remains in the EV region)
In step S51, the engine stop process (HEV → EV mode switching request) started in step S44 is continued.

[Operational effects of engine start / stop control of the fourth embodiment]
In the engine start / stop control according to the above-described embodiment, even when the engine stop process is stopped, no shock is generated and the drivability is not deteriorated. During the period corresponding to the instants t1 to t3 in FIG. (Step S61), when the accelerator opening APO increases while passing through the engine stop line (HEV → EV mode switching line) (step S47, instantaneous t2 in FIG. 12),
Since the engine stop process started at step S44 at the instant t1 is canceled at the instant t2 (step S48 and step S62),
The same effects as those of the third embodiment described above can be achieved.

Further, in the fourth embodiment, when the engine stop process is canceled, a shock occurs, for example, when the drivability is adversely affected (step S61).
Even if the accelerator opening APO increases while passing the engine stop line (HEV → EV mode switching line) (step S47),
Since the engine stop process is not canceled by continuing the engine stop process in step S51,
By canceling the engine stop process, it is possible to reliably avoid adverse effects on drivability such as a shock.

1 is a schematic plan view showing a power train of a hybrid vehicle to which an engine start / stop control device of the present invention can be applied. FIG. 2 is a block diagram showing a control system for the power train shown in FIG. FIG. 3 is a functional block diagram of an integrated controller in the control system shown in FIG. FIG. 4 is a characteristic diagram of a target driving force used when a target driving force calculation unit in FIG. 3 obtains a target driving force. FIG. 2 is an area diagram showing an electric travel (EV) mode area and a hybrid travel (HEV) mode area of a hybrid vehicle. It is a characteristic diagram which shows the target charging / discharging amount characteristic with respect to the battery electrical storage state of a hybrid vehicle. It is engine torque increase progress explanatory drawing which shows the increase progress of the engine torque to the best fuel consumption line according to a vehicle speed. 4 is a flowchart showing a first example of an engine start / stop control program executed by an operating point command unit in FIG. FIG. 9 is an operation time chart of the engine start / stop control program shown in FIG. FIG. 9 is a flowchart similar to FIG. 8, showing an engine start / stop control device according to a second embodiment of the present invention. FIG. 9 is a flowchart of an engine start / stop control program similar to FIG. 8, showing an engine start / stop control apparatus according to a third embodiment of the present invention. 12 is an operation time chart of the engine start / stop control program shown in FIG. FIG. 9 is a flowchart of an engine start / stop control program similar to FIG. 8, showing an engine start / stop control apparatus according to a fourth embodiment of the present invention;

Explanation of symbols

1 Engine (Power source)
2 Drive wheels (rear wheels)
3 Automatic transmission 4 Motor / generator shaft 5 Motor / generator (power source)
6 First clutch 7 Second clutch 8 Differential gear unit 9 Battery
10 Inverter
11 Engine rotation sensor
12 Motor / generator rotation sensor
13 Transmission input rotation sensor
14 Transmission output rotation sensor
15 Accelerator position sensor
16 Battery charge sensor
20 Integrated controller
21 Engine controller
22 Motor / generator controller
30 Target driving force calculator
40 Operation mode selector
50 Target charge / discharge amount calculator
60 Operating point command section
70 Shift control

Claims (6)

An electric travel mode comprising an engine and a drive motor as a power source, a clutch interposed between the engine and the drive motor, and traveling only by the power from the drive motor while releasing the clutch and stopping the engine; In a hybrid vehicle having a hybrid travel mode in which the clutch is engaged and the engine is started and the vehicle is driven by power from both the engine and the drive motor,
Mode switching determination means for determining a mode switching request between the hybrid traveling mode and the electric traveling mode based on a decrease and increase change that reaches a set value of the vehicle required load requested by the driver through an accelerator operation;
When the mode switching request is determined by the mode switching determination means, engine switching start means for starting engine stop and start processing in response to the mode switching request;
Before the engine stop and start processing started by the engine switching start means is completed, there is a change in the return direction so as to reach the set value of the vehicle required load, and the state of the clutch is the engine Mode switching canceling means for canceling the mode switching request when there is a change in the return direction of the vehicle required load in the return direction while the shock is not worsened by stopping or stopping the starting process;
Engine switching stop means for stopping the engine stop and start processing in response to the mode switching request when the mode switching request is canceled by the mode switching canceling means. Vehicle engine start / stop control device. In the engine start / stop control device for a hybrid vehicle according to claim 1,
The state of the clutch that does not exacerbate the shock by stopping the engine and starting process is as follows:
  If the stop of the engine stop and the start process is the stop of the engine start process, the clutch has a transmission torque capacity that is less than a transmission torque capacity that overcomes engine friction,
  An engine start / stop control device for a hybrid vehicle, wherein the clutch has a transmission torque capacity to start slipping when the engine stop / start process stop is the engine stop process stop. A first clutch as the clutch interposed between the engine and the drive motor, and a second clutch interposed between the drive motor and the drive wheel,
By releasing the first clutch and engaging the second clutch, it is possible to select an electric travel mode in which the driving wheel is driven only by power from the drive motor, and both the first clutch and the second clutch are engaged. By doing so, it is possible to select a hybrid travel mode in which the drive wheels are driven by power from both the engine and the drive motor,
While the electric travel mode is selected, the engine can be started with the power from the drive motor and the mode can be switched to the hybrid travel mode by causing the first clutch to engage and advance while slipping the second clutch. In the engine start / stop control device for a hybrid vehicle according to claim 1 or 2 ,
When the mode switching request is switching from the electric travel mode with engine start to the hybrid travel mode, the mode switch canceling unit is configured to perform the vehicle required load during the engine start process started by the engine switching start unit. And the state of the first clutch and the second clutch may exacerbate the shock even when the engine start process is canceled due to the cancellation of the mode switching request. An engine start / stop control device for a hybrid vehicle, wherein the mode switching request is canceled when there is a change in the return direction of the vehicle required load while the vehicle is not in a state. In the engine start / stop control device for a hybrid vehicle according to claim 3,
The state of the first clutch and the second clutch that does not exacerbate the shock even when the engine start process is stopped is a slip state that does not cause a shock even when the second clutch is immediately engaged, and the first clutch An engine start / stop control device for a hybrid vehicle, wherein the engine has a transmission torque capacity that is less than a transmission torque capacity that overcomes engine friction. A first clutch as the clutch interposed between the engine and the drive motor, and a second clutch interposed between the drive motor and the drive wheel,
By releasing the first clutch and engaging the second clutch, it is possible to select an electric travel mode in which the driving wheel is driven only by power from the drive motor, and both the first clutch and the second clutch are engaged. By doing so, it is possible to select a hybrid travel mode in which the drive wheels are driven by power from both the engine and the drive motor,
While the electric travel mode is selected, the engine can be started with the power from the drive motor and the mode can be switched to the hybrid travel mode by causing the first clutch to engage and advance while slipping the second clutch. In the engine start / stop control device for a hybrid vehicle according to any one of claims 1 to 4 ,
When the mode switching request is switching from the hybrid traveling mode with engine stop to the electric traveling mode, the mode switching canceling unit is configured to perform the vehicle requested load during the engine stop process started by the engine switching starting unit. And the state of the first clutch and the engine torque does not deteriorate the shock even when the engine stop process is canceled due to the cancellation of the mode switching request. An engine start / stop control device for a hybrid vehicle, wherein the mode switching request is canceled when there is a return direction change of the vehicle required load while the vehicle is in a state. In the engine start / stop control device for a hybrid vehicle according to claim 5,
  The state of the first clutch and engine torque that does not exacerbate the shock by stopping the engine stop process is a state in which the engine torque is 0 and the first clutch has a transmission torque capacity to start slipping. An engine start / stop control device for a hybrid vehicle, characterized in that:

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