JP3870945B2 - How to start an engine when the driving force of a vehicle with a hybrid transmission increases rapidly - Google Patents

Description

  The present invention relates to a method for starting an engine when a driving force of a vehicle equipped with a hybrid transmission is suddenly increased. In particular, when the engine is started due to a sudden increase in the required driving force, torque corresponding to the sudden increase in the required driving force is applied to the drive wheels. It is related with the technique of starting an engine so that it may go to.

  The hybrid transmission can cause the vehicle to travel electrically only by the power from the motor, or can travel hybridly by the engine power input via the clutch and the power from the motor.

In the case of a vehicle equipped with a hybrid transmission, at the time of starting, electric traveling is mostly used from the viewpoint of smooth starting and easy control.
By the way, when the vehicle speed exceeds a certain level after starting, the motor speed reaches the allowable upper limit or the driving force becomes insufficient. Therefore, instead of the power from the motor or in combination with this, the power from the engine It is usual to run a vehicle.

  Therefore, when starting, the clutch between the hybrid transmission and the engine is engaged during the electric running to crank the engine. When the engine reaches the startable speed, the engine is ignited and supplied with fuel. It needs to be started.

As an engine starting technique at the time of switching from electric traveling to engine traveling, for example, the one disclosed in Patent Document 1 has been proposed.
In this engine starting technology, when switching from electric driving to engine driving, a part of the electric energy is spent on starting the engine, causing a temporary decrease in driving force, and a deceleration shock called pulling down of driving force occurs. In order to prevent this, the engine is started by both the electric travel motor and the engine starter.
JP-A-11-082611

  By the way, when the engine is started due to a sudden increase in the required driving force requested by the driver through the accelerator operation, it is necessary to start the engine in such a manner that as much torque as possible is directed to the drive wheels to match the sudden increase in the required driving force. There is.

However, as described in Patent Document 1, when the engine is started by both the electric running motor and the engine starting starter, a part of the electric energy is consumed for starting the engine. Although we can prevent the deceleration shock caused by the temporary decline,
It is possible not to start the engine in such a way that a large torque is directed to the drive wheels so as to match the sudden increase in the required drive force, but to direct a large drive force that matches the required drive force that the driver desires in the accelerator operation to the wheels. Can not.
Thus in the prior proposed art, upon start of the engine due to the rapid increase of the required driving force, resulting in a problem that the feel shortage driving the driver.

In the present invention, there is a clutch between the hybrid transmission and the engine, and the engine power is input to the hybrid transmission via the clutch. Therefore, the clutch is not completely fastened immediately after the engine is started. Based on the fact recognition that if the slip engagement is performed, the inertia torque is added to the engine torque by this slip engagement, and a large driving force higher than the engine torque can be directed to the wheels.
An object of the present invention is to propose a method for starting an engine at the time of sudden increase in driving force of a vehicle equipped with a hybrid transmission that realizes the idea and solves the problem related to insufficient driving force at the time of sudden increase in driving force.

For this purpose, the engine starting method at the time of sudden increase in driving force of a vehicle equipped with a hybrid transmission according to the present invention is as follows.
First of all, the premised hybrid transmission has a planetary gear set and has a motor coupled to a rotating member of the planetary gear set.
In this hybrid transmission, another rotating member of the planetary gear set is coupled to the engine via a clutch, and another rotating member of the planetary gear set is coupled to a drive wheel via a transmission output shaft. Mounted on the vehicle.
The hybrid transmission causes the vehicle to travel electrically only by the power from the motor, or to travel hybridly by the engine power input through the clutch and the power from the motor.

When starting the engine in response to the sudden increase in the driving force required by the driver during the above electric running,
The engine is cranked by slip-engaging the clutch that has been released during electric travel.
When the engine speed reaches the startable speed by cranking, an engine start command is issued, and at the same time, the engagement force of the clutch in the slip engagement state is temporarily reduced.

The engine speed (the engine speed on the clutch side) started in response to the start command increases, and the engine inertia (the engine speed on the clutch side) is higher than the speed on the transmission side of the clutch. After reaching the set rotational speed for determining whether torque can be added , the clutch is put into the slip engagement state again so that the inertia torque is added to the engine torque and output .

According to the engine starting method at the time of sudden increase in driving force during electric traveling according to the present invention,
After starting the engine the engine speed subsequently when (engine side rotational speed of clutch) becomes high engine inertia torque plus possible determination setting rotational speed transmission-side revolution speed of the clutch, a clutch, Inatoruku is plus the engine torque In order to return to the slip fastening state so that it is output ,
Compared to the case where the clutch is completely engaged immediately after starting the engine, the inertia torque is added to the engine torque by the slip of the clutch, so that a driving force larger than the engine torque can be directed to the wheel, and the required driving force without feel the big insufficient driving force to the driver also I engine starting der at the time of explosion, it is possible to solve the conventional problems in this regard.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a drive system of a vehicle equipped with a hybrid transmission 1 that can implement the engine starting method of the present invention, together with its control system.

  The drive system of the vehicle includes a hybrid transmission 1, an engine 2 on the input side thereof, a clutch 3 interposed therebetween, a differential gear device 4 on the output side of the hybrid transmission 1, and the hybrid transmission 1. The left and right drive wheels 5L and 5R are distributed and transmitted by the differential gear device 4.

The hybrid transmission 1 has the following configuration as shown in FIG. 2, which is useful as a transmission for a front engine / rear wheel drive vehicle (FR vehicle).
That is, the hybrid transmission 1 includes two simple planetary gear sets 21 and 22 arranged coaxially in the axial direction (left and right in the drawing).

A planetary gear set 21 on the side far from the engine 2 is constituted by a ring gear R1, a sun gear S1, and a pinion P1 meshed with these gears,
The planetary gear set 22 on the side close to the engine 2 is constituted by a ring gear R2, a sun gear S2, and a pinion P2 meshed with these gears.

Here, the pinion P2 of the planetary gear set 22 is a long pinion extending to the planetary gear set 21, and the pinion P2 is also meshed with the pinion P1 of the planetary gear set 21,
The pinions P1 and P2 are rotatably supported on a common carrier C so that the planetary gear sets 21 and 22 constitute a Ravigneaux type planetary gear set.

This Ravigneaux type planetary gear set is provided with a composite current two-layer motor 25 coaxially. The composite current two-layer motor 25 coaxially connects an inner rotor 25ri and an annular outer rotor 25ro surrounding the inner rotor 25ri. An annular stator 25s that is rotatably supported and is coaxially arranged in an annular space between the inner rotor 25ri and the outer rotor 25ro is fixed to the transmission case.
The annular stator 25s and the inner rotor 25ri constitute a first motor / generator MG1 as an inner motor / generator, and the annular stator 25s and the outer rotor 25ro constitute a second motor / generator MG2 as an outer motor / generator. Configure.

  A first motor / generator MG1 (inner rotor 25ri) is coupled to the sun gear S1 in a Ravigneaux type planetary gear set composed of planetary gear sets 21, 22, and a second motor / generator MG2 (outer rotor 25ro) is coupled to the sun gear S2. Join.

  When the hybrid transmission 1 configured as described above is inserted into the vehicle drive system, the ring gear R2 is coupled to the output shaft of the engine 2 via the clutch 3, and the carrier C is coupled to the output shaft 24 via the output gear set 23. The output shaft 24 is coupled to the input of the differential gear device 4 as shown in FIG.

  As shown in FIG. 1, the vehicle drive system control system configured as described above includes an engine controller 6 that controls the engine 2 including the start of the engine 2, and a clutch controller 7 that includes a hydraulic pressure source that controls the fastening force of the clutch 3. And a motor controller 8 for controlling the motor / generators MG1, MG2 in the hybrid transmission 1 and an integrated controller 9 for these controllers 6-8.

The integrated controller 9 receives a signal from an engine rotation sensor 11 that detects an engine rotation speed (engine-side rotation speed of the clutch 3) Ne and an input that detects a transmission input rotation speed (transmission-side rotation speed of the clutch 3) Ni. A signal from the rotation sensor 12 and a signal from an accelerator opening sensor 13 for detecting an accelerator pedal depression amount (accelerator opening) APO are input,
Predetermined calculations are performed based on these input information, and an engine start command and a command related to the target engine torque Te * are given to the engine controller 6, and a target clutch engagement force Tc * is given to the clutch controller 7. Further, a command relating to the target torques Tm1 * and Tm2 ^* of the motor / generators MG1 and MG2 is supplied to the motor controller 8.

When the engine controller 6 receives an engine start command or a command related to the target engine torque Te * from the integrated controller 9, the engine controller 6 starts the engine 2 or controls the torque so that these are achieved.
When the clutch controller 7 receives a command related to the target clutch engagement force Tc * from the integrated controller 9, the clutch controller 7 supplies the clutch engagement hydraulic pressure Pc that achieves this to the clutch 3, and controls the clutch engagement force to become a command value. ,
When the motor controller 8 receives a command related to the target motor / generator torques Tm1 * and Tm2 ^* from the integrated controller 9, the motor controller 8 controls the torque of the motor / generators MG1 and MG2 so that these are achieved.

As shown in FIG. 3 and FIG. 4, the integrated controller 9 performs the engine start control when the driving force suddenly increases during electric travel according to the present invention, and as illustrated in FIG. 5 which is an operation time chart from the start of the vehicle. To run.
Figure 3 is determined by the main routine, first in step S 1, the driver based on the accelerator opening APO is whether requests rapid increase of the driving force.
In this determination, it is determined that the required driving force of the driver has rapidly increased when the changing speed of the accelerator opening APO is equal to or higher than the set speed and the accelerator opening APO is equal to or higher than the set value APOs shown in FIG. .
Here, the set value APOs related to the accelerator opening APO is increased as the vehicle speed increases, so that a rapid increase determination of the driving force can be accurately performed for each vehicle speed.

While it is determined in step S1 that the driver does not request a sudden increase in driving force, the main routine in FIG. 3 is not executed until the control is returned to step S1 and the driver requests a sudden increase in driving force. To wait.
Only after the instant t1 in FIG. 5 at which it is determined in step S1 that the driver has requested a sudden increase in driving force, the control proceeds to step S2, where the target clutch engagement force Tc * is changed from 0 as shown in FIG. Increase to a predetermined fastening force Tc1 *.

The predetermined fastening force Tc1 * is a fastening force that increases the engine speed at a predetermined speed suitable for cranking.
The clutch controller 7 supplies a clutch engagement hydraulic pressure Pc as shown in FIG. 5 for realizing the target clutch engagement force Tc * to the clutch 3, and makes the engagement force of the clutch 3 the above target value. To the slip fastening state.

The engine 2 is cranked by the slip engagement state of the clutch 3, and the engine rotational speed Ne increases as shown after the instant t1 in FIG.
In step S3 of FIG. 3, it is determined whether or not the engine has reached a startable rotation speed by ignition depending on whether or not the engine rotation speed Ne has reached the startable rotation speed Nig illustrated in FIG.
Step S3 returns the control to step S2 until the engine reaches a startable speed, where the clutch 3 is maintained in the slip engagement state and the engine speed Ne is further increased.

  At the instant t2 in FIG. 5 when the engine speed Ne reaches the startable speed Nig, step S3 advances the control to step S4. In step S4, the integrated controller 9 issues an engine start command to the engine controller 6 and releases the clutch (Tc * = 0) Command is issued to the clutch controller 9.

  When the engine controller 6 receives the engine start command, the engine controller 6 starts the engine 2 by an ignition command or a fuel injection command to the engine. By this start, the engine speed Ne and the engine torque Te are about the time after the instant t2 in FIG. To rise.

When the clutch controller 9 receives the clutch release (Tc * = 0) command, the clutch engagement hydraulic pressure Pc is set to 0 as after the instant t2 in FIG. 5, and the clutch 3 is released according to the command.
Such release of the clutch 3 can eliminate a drag energy loss due to the slip of the clutch 3 to promote a rapid increase in the engine speed Ne, suppress heat generation due to the slip of the clutch 3, and then perform slip engagement described later. The heat load can be given a margin.

In order to realize a further rapid increase in the engine speed Ne after the instant t2 in FIG. 5, the engine controller 7 is designed so that the maximum engine torque is generated at every moment after the instant t2. It is good to control the engine 2 via this.
Further, although the clutch 3 is in the released state after the instant t2 in FIG. 5, as long as the purpose of giving the heat load of the clutch 3 after that by suppressing the heat generation of the clutch 3 is achieved, the clutch 3 is Instead of the released state, the fastening force may be reduced.

  In step S5 of FIG. 3, the engine speed (engine-side speed of the clutch 3) Ne is higher than the transmission-side speed (transmission input speed) Ni of the clutch 3 as shown in FIG. Whether or not the set value Nes has been exceeded or not, that is, whether or not the clutch 3 is in the slip engagement state, the inertia torque is added to the engine torque and a large driving force exceeding the engine torque can be directed to the wheels. Check whether or not.

  Here, the set value Nes related to the engine speed Ne should correspond to the engine speed for generating the maximum engine torque. In this case, the engine torque to which the inertia torque is added is the maximum torque. As a result, the driving force can be increased, and the increase in the engine speed Ne required to achieve this can be quickly completed.

  While it is determined in step S5 that Ne <Nes, that is, while it is determined that the engine torque of the inertia torque is not added even when the clutch 3 is in the slip engagement state, the process waits until Ne ≧ Nes, and Ne ≧ Nes. At the instant t3 in FIG. 5, the control proceeds to step S6, and the clutch 3 is brought into the slip engagement state for increasing the driving force.

The processing in step S6 is as shown in FIG. 4. First, in step S11, the target engine torque Te * to the engine controller 6 is set to the maximum engine torque under the momentary engine speed, and the clutch 3 is again turned on. The engine is controlled so that the maximum engine torque is generated at the momentary engine speed after the instant t3 in FIG.
In the next step S12, the target clutch engagement force Tc * to the clutch controller 7 is set to a set value Tc2 * as illustrated in FIG. 5, and this set value Tc2 * is the target engine torque Te * (maximum engine torque). Therefore, the set value is set such that the engine speed Ne is kept higher than the transmission-side speed Ni of the clutch 3, that is, the clutch 3 is brought into a slip engagement state.

  Thus, in step S11 and step S12, after the instant t3 in FIG. 5, the engine is controlled so that the maximum engine torque is generated at every momentary engine speed, and at the maximum engine torque, the engine speed Ne. Therefore, the clutch engagement force Tc * is controlled so that the rotation speed Ni is kept higher than the transmission side rotational speed Ni of the clutch (the clutch 3 is brought into the slip engagement state).

In the slip engagement state of the clutch 3 in which the engine speed Ne is kept higher than the transmission side rotation speed Ni of the clutch as in the latter, the inertia torque is added to the engine torque and a large driving force higher than the engine torque is applied to the wheels. As can be seen from the waveform of the driving force To after the instant t3 in FIG. 5, the driving force To can be increased to match the sudden increase in the required driving force. We can alleviate power shortage.
Further, at this time, since the former control for controlling the engine so that the maximum engine torque is generated at every momentary engine speed is controlled so that the engine torque Te becomes the maximum value, after the instant t3 in FIG. As can be seen from the waveform of the driving force To, the driving force To can be made larger to meet the sudden increase in required driving force, and the lack of driving force when the driving force suddenly increases can be more reliably alleviated. .

In the next step S13 in FIG. 4, the amount of heat generated Q of the clutch 3 after the instant t3 in FIG. 5 to re-engage the clutch 3 in the slip engagement state, the clutch forward / backward rotational speed difference, the clutch engagement force, and the elapsed time from the instant t3. Calculate and estimate based on time.
In step S14, it is checked whether or not the driving slip of the wheel tire has generated a driving slip. If it has not occurred, step S15 is skipped, and if it has occurred, tire slip suppression control is performed in step S15.
In the control in step S15, the clutch 3 engagement force (target clutch engagement force Tc *) is reduced so that the driving slip of the wheel tire is suppressed, and further, the engine rotational speed is set to an allowable upper limit by the decrease of the clutch engagement force. The engine torque (target engine torque Te *) is reduced in order to avoid engine overspeed exceeding.

In step S16, whether or not the clutch 3 is overheated is checked based on whether or not the heat generation amount Q of the clutch 3 after the instant t3 in FIG. 5 estimated in step S13 is equal to or greater than the set value Qs. For example, the control is returned to step S11, and the loop of steps S11 to S16 is repeated.
When the clutch 3 is overheated that is determined as Q ≧ Qs in step S16, the overheat countermeasure process for the clutch 3 is performed by the processes in steps S17 and S18.
In step S17, the target engine torque Te * to the engine controller 6 is reduced to control the engine so that the engine torque is reduced, thereby reducing the slip amount of the clutch 3 and taking measures against overheating.
In step S18, the target clutch engagement force Tc * to the clutch controller 7 is increased to make it difficult for the clutch 3 to slip, thereby taking measures against overheating of the clutch 3.

  When the engine starting method at the time of sudden increase in the driving force according to the above embodiment is adopted, the vehicle acceleration G is shown by a solid line in FIG. In comparison with the time-series change of the vehicle acceleration G indicated by the broken line when the clutch 3 is fully engaged between the start time and the instant t1, the above-mentioned inertia torque is added. Only the portion indicated by hatching corresponding to the minute becomes larger, and it is possible to obtain a vehicle driving force that matches the sudden increase in the required driving force.

  Note that the vehicle acceleration G is when the clutch 3 is in the slip engagement state as in this embodiment, and when the clutch 3 is fully engaged after the instant t1 in FIG. Therefore, it is advantageous to obtain a large driving force when the clutch 3 is switched from the slip engagement state to the complete engagement state at this instant t1 and then the clutch 3 is completely engaged. Of course.

1 is a system diagram showing a drive system of a vehicle equipped with a hybrid transmission capable of carrying out an engine start method at the time of sudden increase in driving force according to the present invention, together with its control system. FIG. 2 is a diagrammatic longitudinal side view of the hybrid transmission in FIG. 1. 2 is a flowchart showing a main routine when the integrated controller in FIG. 1 executes an engine starting method at the time of sudden increase in driving force according to the present invention. It is a flowchart which shows the subroutine of the clutch slip control for a driving force increase in the main routine. It is an operation | movement time chart when the engine starting method at the time of the driving force rapid increase by this invention is performed. It is a time chart which shows the time series change of the vehicle acceleration at the time of performing the engine starting method at the time of the driving force rapid increase by this invention compared with the time series change of the vehicle acceleration at the time of performing a normal method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid transmission 2 Engine 3 Clutch 4 Differential gear apparatus
5L left drive wheel
5R Right drive wheel 6 Engine controller 7 Clutch controller 8 Motor controller 9 Integrated controller
11 Engine rotation sensor
12 Input rotation sensor
13 Accelerator position sensor
21 Simple planetary gear set
22 Simple planetary gear set
23 Output gear set
24 output shaft
25 Compound current 2-layer motor
MG1, MG2 Motor / Generator

Claims (10)

A hybrid transmission having a planetary gear set and having a motor coupled to a rotating member of the planetary gear set is connected to the engine via a clutch with the other rotating member of the planetary gear set, and another rotation of the planetary gear set. A vehicle in which a member is mounted so as to be coupled to a drive wheel via a transmission output shaft ,
In the hybrid transmission, the vehicle is caused to travel electrically only by the power from the motor, or the hybrid power is driven by the engine power input through the clutch and the power from the motor.
When starting the engine in response to a sudden increase in the driving force required by the driver during the electric running,
Crank the engine by slip-engaging the clutch that was released during electric travel,
When the engine speed reaches the startable speed by the cranking, the engine start command is issued, and at the same time, the engagement force of the clutch in the slip engagement state is reduced,
After the engine speed rises due to the start and reaches the engine inertia torque setting speed that is higher than the transmission-side speed of the clutch, the clutch is added to the engine torque and the inertia torque is added to the engine torque. A method for starting an engine when a driving force of a vehicle equipped with a hybrid transmission is suddenly increased. The engine start method according to claim 1,
The engine is controlled so that the maximum engine torque is generated at every momentary engine speed from when the engine start command is issued until the clutch is brought into the slip engagement state again. A method for starting the engine when the driving force of a vehicle equipped with a hybrid transmission increases rapidly. The engine starting method according to claim 1 or 2,
A hybrid transmission that controls engine torque and clutch engagement force so that the engine speed is maintained higher than the transmission-side rotation speed of the clutch after the clutch is brought into the slip engagement state again. How to start the engine when the driving force of the equipped vehicle suddenly increases. The engine starting method according to any one of claims 1 to 3,
After starting the clutch again in the slip engagement state, the engine is controlled so that the maximum engine torque is generated at every momentary engine speed. Method. The engine start method according to any one of claims 1 to 4,
After the clutch is brought into the slip engagement state again, when the heat generation amount of the clutch becomes a set value or more, the engagement force of the clutch is increased, and the engine at the time of sudden increase in driving force of the hybrid transmission mounted vehicle How to start. The engine starting method according to any one of claims 1 to 5,
After the clutch is brought into the slip engagement state again, when the heat generation amount of the clutch becomes a set value or more, the clutch is controlled to increase the engagement force of the clutch and to decrease the engine torque. How to start the engine when the driving force of a vehicle equipped with a hybrid transmission suddenly increases. The engine starting method according to any one of claims 1 to 6,
A method of starting an engine when a driving force of a vehicle equipped with a hybrid transmission is suddenly increased, when a driving slip of a wheel occurs after the clutch is brought into a slip engagement state again . The engine start method according to claim 7,
A method for starting an engine when a driving force of a vehicle equipped with a hybrid transmission is suddenly increased, wherein an engine torque is reduced to prevent over-rotation of the engine when a driving slip of a wheel is generated, together with a reduction of an engagement force of the clutch. The engine starting method according to any one of claims 1 to 8,
The hybrid transmission characterized in that the set value relating to the engine speed for determining that the clutch should be brought into the slip engagement state again corresponds to the engine speed for generating the maximum engine torque. How to start the engine when the driving force of the equipped vehicle suddenly increases. The engine starting method according to any one of claims 1 to 9,
A sudden increase in the required driving force is determined when the accelerator opening operated by the driver exceeds a set value, and the set value is increased as the vehicle speed increases. When the engine starts.

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