JP2016210208A - Control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a hybrid vehicle which can suppress generation of gear rattle caused by reverse of a direction of motor torque.SOLUTION: The control device of a hybrid vehicle, when stopping an internal combustion engine, reverses a direction of motor torque τg to be outputted from a first motor/generator from a negative direction to a normal direction at the time t3 when engine rotation speed gets lower than a predetermined value Neth and crank shaft torque τe is switched from a negative value to a normal value in the opposite direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device applied to a hybrid vehicle provided with an engine and a motor / generator in a state where torque can be transmitted to each other.

  As a control device for a hybrid vehicle, a damper provided between the engine and the motor / generator is twisted in the negative direction when a torque in the negative direction that reduces the engine speed is applied to the engine shaft when the engine is stopped. As described above, a motor / generator that outputs motor torque is known (Patent Document 1). In addition, there is Patent Document 2 as a prior art document related to the present invention.

JP 2010-137823 A JP 2010-14492 A

  In a hybrid vehicle, in order to prevent the engine speed from decreasing to 0 and causing reverse rotation by continuing to apply negative torque when the engine is stopped, the motor torque direction is changed when the engine speed decreases to a predetermined value. There is a case where torque reversal control for reversing is performed. The engine shaft torque when the engine is stopped alternately switches between a negative value corresponding to the compression stroke in which the transmission direction is the direction from the motor / generator to the engine and a positive value corresponding to the expansion stroke in the opposite direction. Therefore, when the above control for reversing the direction of the motor torque when the engine is stopped is performed, if the timing for reversing the direction of the motor torque and the timing for switching the positive value and the negative value of the engine shaft torque are inconsistent, When a gear train is interposed between the motor and the generator, there is a risk that a rattling noise will occur when the gears collide between backlashes of the gear train.

  Therefore, an object of the present invention is to provide a control device for a hybrid vehicle that can suppress the generation of rattling noise associated with the reversal of the direction of the motor torque.

  The hybrid vehicle control device of the present invention is applied to a hybrid vehicle in which an engine and a motor / generator are provided in a state where torque can be transmitted to each other, and a gear train is interposed between the engine and the motor / generator, When the engine is stopped, a negative motor torque, which is a direction to decrease the engine speed, is output from the motor / generator, and the engine speed is decreased from a predetermined value before being output from the motor / generator. A control device for a hybrid vehicle that reverses the direction of motor torque in a positive direction that is a direction of increasing engine speed, wherein the engine speed is lower than the predetermined value and the engine shaft torque of the engine is The transmission direction of the engine shaft torque is changed from the motor / generator to the engine. The direction of motor torque output from the motor / generator is reversed from the negative direction to the positive direction when switching from a negative value that is a value in the direction toward the engine to a positive value that is a value in the opposite direction. .

  According to this control device, the timing for reversing the direction of the motor torque matches the timing for switching between the positive value and the negative value of the engine shaft torque. Therefore, even if the direction of the motor torque is reversed, The relationship in which one meshing gear is pressed against the other gear is maintained. Thereby, generation | occurrence | production of the rattling sound accompanying reversal of the direction of a motor torque can be suppressed.

The figure which showed the whole structure of the hybrid vehicle which concerns on one form of this invention. The timing chart which showed an example of the control result. The conceptual diagram which showed the calculation method of the motor torque. The flowchart which showed an example of the control routine. The figure which showed an example of the calculation map used for calculation of a motor torque. The figure which showed the time change of a crankshaft torque and a damper load torque. The timing chart which showed an example of the control result concerning a reference example. The conceptual diagram which showed the calculation method of the motor torque which concerns on a reference example. The flowchart which showed an example of the control routine which concerns on a reference example. The figure which showed an example of the calculation map used for calculation of the motor torque which concerns on a reference example.

  As shown in FIG. 1, the vehicle 1 is configured as a hybrid vehicle in which a plurality of power sources are combined. The vehicle 1 includes an internal combustion engine 3 as an engine and two motor generators 4 and 5 as a driving power source. The internal combustion engine 3 is configured as a reciprocating spark ignition internal combustion engine having a plurality of cylinders (not shown).

  The internal combustion engine 3 and the first motor / generator 4 are connected to a power split mechanism 6. The first motor / generator 4 functions as a generator that generates power by receiving the power of the internal combustion engine 3 divided by the power split mechanism 6 and also functions as an electric motor driven by AC power. Similarly, the second motor / generator 5 functions as an electric motor and a generator.

  The power split mechanism 6 is configured as a single pinion type planetary gear mechanism. The power split mechanism 6 is a planet that holds a sun gear S as an external gear, a ring gear R as an internal gear arranged coaxially with the sun gear S, and a pinion P meshing with these gears S and R so as to be able to rotate and revolve. Carrier C. The engine torque output from the internal combustion engine 3 is transmitted to the planet carrier C of the power split mechanism 6 via the torsional damper 10. A crankshaft 3 a of the internal combustion engine 3 is connected to the input side of the torsional damper 10, and a planet carrier C is connected to the output side of the torsional damper 10. The first motor / generator 4 is connected to the sun gear S of the power split mechanism 6. The internal combustion engine 3 and the first motor / generator 4 are connected via a power split mechanism 6 and can transmit torque to each other. Since power split mechanism 6 includes a gear train, a gear train is interposed between internal combustion engine 3 and first motor / generator 4.

  The ring gear R of the power split mechanism 6 is provided with an external gear output gear 12 on the outer periphery thereof. The output gear 12 meshes with the driven gear 13. The motor shaft 14 of the second motor / generator 5 is provided with a motor gear 15 that meshes with the driven gear 13. The driven gear 13 is fixed to the counter shaft 17, and the drive gear 18 is fixed to the counter shaft 17. The drive gear 18 meshes with the ring gear 21 of the differential mechanism 20. Therefore, the torque output from the output gear 12 and the motor torque of the second motor / generator 5 are transmitted to the differential mechanism 20 via the driven gear 13 and the drive gear 18. The torque transmitted to the differential mechanism 20 is distributed to the left and right drive wheels 25, respectively.

  Control of each part of the vehicle 1 is controlled by an electronic control unit (ECU) 30 configured as a computer. The ECU 30 performs various controls on the internal combustion engine 3 and the motor / generators 4 and 5. Various information on the vehicle 1 is input to the ECU 30. For example, the ECU 30 outputs an output signal of an accelerator opening sensor 31 that outputs a signal corresponding to the amount of depression of the accelerator pedal 26, an output signal of a vehicle speed sensor 32 that outputs a signal corresponding to the vehicle speed of the vehicle 1, and the internal combustion engine 3. The output signal of the crank angle sensor 33 that outputs a signal corresponding to the crank angle of the crank angle sensor 33 is input.

  The ECU 30 calculates the required driving power required by the driver with reference to the output signal of the accelerator opening sensor 31 and the output signal of the vehicle speed sensor 32, and performs various operations so that the system efficiency for the required driving power is optimized. The vehicle 1 is controlled while switching modes. For example, in the low load region where the thermal efficiency of the internal combustion engine 3 decreases, the EV mode in which the combustion of the internal combustion engine 3 is stopped and the second motor / generator 5 is driven is selected. When the torque is insufficient with the internal combustion engine 3 alone, a hybrid mode is selected in which the second motor / generator 5 is used as a travel drive source together with the internal combustion engine 3.

  The ECU 30 stops the combustion of the internal combustion engine 3 from the hybrid mode and switches the travel mode to the EV mode when the driving condition changes while the vehicle 1 is traveling, and at the time of the travel stop when the vehicle speed of the vehicle 1 becomes zero. 3 is stopped and the crankshaft is stopped. The stop of the internal combustion engine 3 means a state in which combustion is stopped and the rotational speed of the crankshaft 3a, that is, the engine speed is zero.

  In order to stop the internal combustion engine 3, the ECU 30 performs a fuel cut to stop the combustion of the internal combustion engine 3, and then causes the negative torque to decrease the engine speed to act on the crankshaft 3 a. The generator 4 is controlled. As a result, the engine speed of the internal combustion engine 3 decreases and reaches zero. However, if the above control on the first motor / generator 4 is continued until the engine speed reaches zero, the internal combustion engine 3 may reversely rotate due to inertia. In order to avoid the reverse rotation, the ECU 30 performs torque reversal control for reversing the direction of the motor torque from the negative direction to the positive direction when the engine speed decreases below a predetermined value.

  This embodiment is characterized by the timing of reversing torque in torque reversal control. As shown in FIG. 2, the crankshaft torque τe as the engine shaft torque alternately switches between a negative value corresponding to the compression stroke of the internal combustion engine 3 in which combustion has stopped and a positive value corresponding to the expansion stroke. A negative value is a value in a direction in which the transmission direction of the crankshaft torque τe is directed from the first motor / generator 4 to the internal combustion engine 3, and a positive value is a transmission direction of the crankshaft torque τe in the first motor / generator 4 from the internal combustion engine 3. The value in the direction toward.

  The motor torque τg is controlled to the negative set value τgm from the control start time t0. Therefore, the engine speed Ne gradually decreases. At time t1, the engine speed Ne reaches a predetermined value Neth. Thereafter, the magnitude (absolute value) of the motor torque τg is gradually reduced starting from time t2. The crank angle θ at time t2 is θm. While the absolute value of the motor torque τg is decreasing, the crankshaft torque τe is a negative value. At time t3, both the crankshaft torque τe and the motor torque τg become zero.

  From time t3, the crankshaft torque τe changes from a negative value to a positive value, and the motor torque τg changes from a negative direction to a positive direction. That is, the ECU 30 reverses the direction of the motor torque τg from the negative direction to the positive direction when the crankshaft torque τe switches from a negative value to a positive value. As a result, the switching timing of the crankshaft torque τe from the negative value to the positive value coincides with the reversal timing of the motor torque τg from the negative direction to the positive direction.

  When the motor torque τg reaches the set value τgp in the positive direction at time t4, the set value τgp is maintained thereafter. The crank angle θ at time t4 is θp. By maintaining the motor torque τg at the set value τgp in the positive direction, the engine speed Ne reaches 0 at time t5. Thereby, the internal combustion engine 3 stops. The inertia of the internal combustion engine 3 and the inertia of the rotating member included in the power transmission path such as a gear train from the first motor / generator 4 to the internal combustion engine 3 exceed the set value τgp. Therefore, even if the motor torque τg is controlled to the set value τgp, the crankshaft 3a does not rotate, so the engine speed Ne is maintained at zero.

  The timing at which the crankshaft torque τe switches from a negative value to a positive value can be known from the crank angle θ. Therefore, as shown in FIG. 3, the crank angle θ is input to the motor torque calculation unit 30a logically configured in the ECU 30, and the motor torque calculation unit 30a converts the motor torque τg corresponding to the crank angle θ to the engine torque. Calculation is made on the condition that the rotational speed Ne reaches a predetermined value Neth. A specific method for calculating the motor torque τg will be described later.

  The above control is realizable when ECU30 performs the control routine of FIG. 4 as an example. The program of the control routine of FIG. 4 is held in the ECU 30, and is read out in a timely manner and repeatedly executed at predetermined intervals.

  In step S <b> 1, the ECU 30 refers to the output signal of the crank angle sensor 33 and acquires the engine speed Ne of the internal combustion engine 3. In step S2, the ECU 30 compares the engine speed Ne acquired in step S1 with a predetermined value Neth, and determines whether or not the engine speed Ne is lower than the predetermined value Neth. If the engine speed Ne is lower than the predetermined value Neth, the process proceeds to step S3. Otherwise, the process proceeds to step S5.

  In step S <b> 3, the ECU 30 refers to the output signal of the crank angle sensor 33 and acquires the crank angle θ. In step S4, the ECU 30 calculates the motor torque τg. The motor torque τg is calculated by, for example, searching the calculation map M shown in FIG. 5 by the ECU 30 and specifying the motor torque τg corresponding to the crank angle θ acquired in step S3. In the calculation map M, the crank angle θ and the motor torque τg are associated with each other. The calculation map M is set so that the motor torque τg becomes zero at the timing when the crankshaft torque τe switches from a negative value to a positive value (crank angle θ = 0).

  In step S5, the ECU 30 sets the motor torque τg to the set value τgm described above. In step S6, the ECU 30 outputs the desired motor torque τg from the first motor / generator 4 by instructing the first motor / generator 4 with the motor torque τg calculated in step S4 or set in step S5. Then, the routine ends.

  According to the control device of the present embodiment, the change in the direction of the motor torque τg after the engine speed Ne drops below the predetermined value Neth synchronizes with the switching from the positive value to the negative value of the crankshaft torque τe, The timing for switching the torque τe from a negative value to a positive value coincides with the timing for reversing the motor torque τg from the negative direction to the positive direction. Therefore, when either one of the crankshaft torque τe and the motor torque τg is 0, a situation in which one of the other is not 0 can be avoided. Therefore, even if the direction of the motor torque τg is reversed, the relationship in which one of the meshing gears included in the gear train interposed between the internal combustion engine 3 and the first motor / generator 4 presses the other gear is maintained. Thereby, generation | occurrence | production of the rattling sound accompanying reversal of the direction of motor torque (tau) g can be suppressed.

(Reference example)
Next, reference examples related to the present invention will be described with reference to FIGS. Since this reference example is the same as the above embodiment except for the control contents, FIG. 1 and the like are referred to for the physical configuration. This reference example is characterized in that the timing for reversing the direction of the motor torque is determined in consideration of damper characteristics such as elasticity of the torsional damper 10 and inertia of the internal combustion engine 3 and the like.

  When torque is transmitted between the internal combustion engine 3 and the first motor / generator 4, it is affected by damper characteristics such as elasticity and damping of the torsional damper 10 interposed therebetween. Further, at that time, it is influenced by the inertia of the internal combustion engine 3 and the inertia of the rotating member existing from the internal combustion engine 3 to the first motor / generator 4.

  Therefore, as shown in FIG. 6, depending on the vehicle speed of the vehicle 1 when the internal combustion engine 3 is stopped, the damper load torque τdmp borne by the torsional damper 10 is delayed in time with respect to the crankshaft torque τe. There may be deviation. Therefore, in the vehicle speed range in which a deviation as shown in FIG. 6 occurs between the crankshaft torque τe and the damper load torque τdmp, the timing at which the negative value and the positive value of the crankshaft torque τe are switched as described above is used as a reference. Inverting the direction of the motor torque τg with reference to the timing at which the negative value and the positive value of the damper load torque τdmp are switched instead of the control can be more realistic control.

  As shown in FIG. 7, the damper load torque τdmp alternates between a negative value and a positive value in the same manner as the crankshaft torque τe. As in the above embodiment, since the motor torque τg is controlled to the negative set value τgm from the control start time t0, the engine speed Ne gradually decreases. At time t1, the engine speed Ne reaches a predetermined value Neth. Thereafter, the absolute value of the motor torque τg is gradually reduced starting from time t2. The damper load torque τdmp at time t2 is τdpm. While the absolute value of the motor torque τg is decreasing, the damper load torque τdmp is a negative value. At time t3, both the damper load torque τdmp and the motor torque τg become zero.

  From time t3, the damper load torque τdmp changes from a negative value to a positive value, and the motor torque τg also changes from a negative direction to a positive direction. That is, the ECU 30 reverses the direction of the motor torque τg from the negative direction to the positive direction when the damper load torque τdmp switches from a negative value to a positive value. As a result, the switching timing of the damper load torque τdmp from the negative value to the positive value coincides with the timing of reversing the motor torque τg from the negative direction to the positive direction.

  The damper load torque τdmp may be detected directly from the output signal of the torque sensor 40 provided on the output side of the torsional damper 10 as shown in FIG. May be.

  τdmp = − (1 + ρ) / ρ · (τg− (Ig · αg + Cg · ωg)) A

  However, in Formula A, ρ is the gear ratio of the power split mechanism 6, αg is the angular acceleration of the first motor / generator 4, ωg is the angular velocity of the first motor / generator 4, Ig is the inertia of the first motor / generator 4, Cg is an attenuation coefficient of the first motor / generator 4. The angular acceleration αg and the angular velocity ωg are calculated by the ECU 30 based on an output signal of a resolver (not shown) that is provided in the first motor / generator 4 and outputs a signal corresponding to the rotation angle θg.

  As is clear from the above formula A, the damper load torque τdmp is a function of the motor torque τg. As shown in FIG. 8, the motor torque τg and the rotation angle θg of the first motor / generator 4 are input to the load torque estimating unit 30b logically configured in the ECU 30, and the load torque estimating unit 30b uses the estimated value as an estimated value. Damper load torque τdmp is output. The estimated value of the damper load torque τdmp and the engine speed Ne are input to the motor torque calculator 30c. Accordingly, the motor torque τg commanded to the first motor / generator 4 is calculated on condition that the engine speed Ne reaches the predetermined value Neth. A specific method for calculating the motor torque τg will be described later.

  When the motor torque τg reaches the set value τgp in the positive direction at time t4, the set value τgp is maintained thereafter. The damper load torque τdpm at this time is τdmpp. By maintaining the motor torque τg at the set value τgp in the positive direction, the engine speed Ne reaches 0 at time t5. As a result, the internal combustion engine 3 is stopped and the engine speed Ne is maintained at zero.

  The above control can be realized by the ECU 30 executing the control routine of FIG. 9 as an example. The program of the control routine of FIG. 9 is held in the ECU 30, and is read out in a timely manner and repeatedly executed at predetermined intervals.

  In step S <b> 11, the ECU 30 refers to the output signal of the crank angle sensor 33 and acquires the engine speed Ne of the internal combustion engine 3. In step S12, the ECU 30 compares the engine speed Ne acquired in step S11 with a predetermined value Neth, and determines whether or not the engine speed Ne is lower than the predetermined value Neth. If the engine speed Ne is lower than the predetermined value Neth, the process proceeds to step S13. Otherwise, the process proceeds to step S15.

  In step S13, the ECU 30 acquires the damper load torque τdmp. The damper load torque τdmp is obtained by calculating based on the output signal of the torque sensor 40 as described above or based on the equation A. In step S14, the ECU 30 calculates the motor torque τg. The motor torque τg can be calculated, for example, by specifying the motor torque τg corresponding to the damper load torque τdmp acquired in step S13 by referring to the calculation map M ′ shown in FIG. . In the calculation map M ′, the damper load torque τdmp and the motor torque τg are associated with each other. The calculation map M ′ is set so that the motor torque τg becomes zero at the timing when the damper load torque τdmp switches from a negative value to a positive value.

  In step S15, the ECU 30 sets the motor torque τg to the set value τgm described above. In step S16, the ECU 30 outputs the desired motor torque τg from the motor / generator 4 by instructing the first motor / generator 4 with the motor torque τg calculated in step S14 or set in step S15. Then, the routine ends.

  According to this reference example, the change in the direction of the motor torque τg is synchronized with the change from the positive value to the negative value of the damper load torque τdmp after the engine speed Ne has decreased below the predetermined value Neth, as in the above embodiment. Thus, the switching timing of the damper load torque τdmp from the negative value to the positive value coincides with the timing of reversal of the motor torque τg from the negative direction to the positive direction. Therefore, even if the direction of the motor torque τg is reversed, the relationship in which one of the meshing gears included in the gear train interposed between the internal combustion engine 3 and the first motor / generator 4 presses the other gear is maintained. Thereby, generation | occurrence | production of the rattling sound accompanying reversal of the direction of motor torque (tau) g can be suppressed.

  The present invention is not limited to the above embodiment, and can be implemented in various forms within the scope of the gist of the present invention. The hybrid vehicle to which the present invention is applied is not limited to the embodiment shown in FIG. 1, and may be a hybrid vehicle including a single motor / generator, for example. Moreover, it is also possible to use the control of the said form and the control of the said reference example properly according to a vehicle speed range.

1 Hybrid vehicle 3 Internal combustion engine
4 1st motor generator (motor generator)

Claims (1)

An engine and a motor / generator are provided in a state capable of transmitting torque to each other, and applied to a hybrid vehicle in which a gear train is interposed between the engine and the motor / generator,
When stopping the engine, a motor torque in the negative direction, which is a direction to decrease the engine speed, is output from the motor / generator, and output from the motor / generator after the engine speed decreases below a predetermined value. The direction of the motor torque to be reversed is reversed to the positive direction, which is the direction of increasing the engine speed,
A control device for a hybrid vehicle,
The engine speed is lower than the predetermined value, and the engine shaft torque of the engine is reversed from a negative value in which the transmission direction of the engine shaft torque is a value in a direction from the motor / generator to the engine. A control apparatus for a hybrid vehicle, wherein the direction of motor torque output from the motor / generator is reversed from the negative direction to the positive direction when the value is switched to a positive value.

Images