JP2016112975A - Output control device of hybrid vehicle - Google Patents

Abstract

An output control device for a hybrid vehicle capable of suppressing an increase in a PN value accompanying an increase in engine torque of an internal combustion engine. An ECU sets an engine torque limit value according to the temperature in the combustion chamber when the temperature in the combustion chamber of the engine is less than a predetermined value, and determines that the engine request output for the engine exceeds the engine torque limit value. In this case, the engine speed of the engine 3 is changed so that the power storage rate of the battery 36 can be maintained above the lower limit value and approaches the engine required output within a range not exceeding the engine torque limit value. [Selection] Figure 1

Description

  The present invention relates to an output control device applied to a hybrid vehicle provided with an internal combustion engine and an electric motor as a driving source for traveling.

  As an output control device applied to a hybrid vehicle, the output limit value of the internal combustion engine is calculated until the piston top surface temperature, which is the combustion chamber temperature, exceeds a predetermined value at the time of low temperature start of the internal combustion engine. By setting the target engine speed and the engine torque limit value based on the battery, and setting the motor torque command value within the battery input / output limit range based on the charge state of the battery to control the internal combustion engine and the motor, One that suppresses the deterioration of emissions caused by incomplete combustion of an internal combustion engine is known (Patent Document 1).

JP 2006-299817 A

  The output control device of Patent Document 1 suppresses an increase in emission that affects the fuel injection amount by limiting the output of the internal combustion engine, and limits the motor torque within an input / output limit range based on the state of charge of the battery. Therefore, the fuel injection amount increases as the torque increases even within the output limit range of the internal combustion engine. Therefore, especially during the cold start of the internal combustion engine, the number of particulate matter (PN: particulate) which is one of the emission values. number) may be an undesirable value.

  Therefore, an object of the present invention is to provide an output control device for a hybrid vehicle that can suppress an increase in PN value accompanying an increase in engine torque of an internal combustion engine.

  An output control device according to the present invention includes an internal combustion engine and an electric motor as a driving source for travel, and both the internal combustion engine and the electric motor can share and generate power as a driving force of the entire vehicle. An output control device for a hybrid vehicle applied to a hybrid vehicle provided with power storage means used for driving, wherein the combustion chamber temperature of the internal combustion engine is less than a predetermined value according to the combustion chamber temperature. And setting means for setting the engine torque limit value of the internal combustion engine, and when it is determined that the engine required output for the internal combustion engine exceeds the engine torque limit value, the power storage rate of the power storage means can be maintained at a predetermined value or more. And a control means for changing the engine speed of the internal combustion engine so as to approach the engine required output within a range not exceeding the engine torque limit value. And, those with a.

  According to this output control device, by setting the engine torque limit value in relation to the PN value, output control is performed such that the engine torque limit value is not exceeded and the storage rate is maintained at a predetermined value or more. Thereby, the deterioration of the PN value accompanying the increase in the torque of the internal combustion engine can be suppressed, and the deterioration of the PN value due to the extra output increase of the internal combustion engine due to the decrease in the storage rate of the power storage means can be suppressed.

The figure which showed the whole structure of the hybrid vehicle to which the output control apparatus which concerns on one form of this invention was applied. The figure which showed the outline | summary of the control which concerns on one form of this invention. The figure which showed the relationship between the difference with an engine request output, and an electrical storage rate. 6 is a flowchart illustrating an example of a control routine according to an embodiment of the present invention.

  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 engine 3 and two motor generators 4 and 5 as driving power sources. The engine 3 is an in-line four-cylinder internal combustion engine including four cylinders 10. The engine 3 corresponds to the internal combustion engine according to the present invention, and the second motor / generator 5 corresponds to the electric motor according to the present invention. The vehicle 1 is configured so that both the engine 3 and the second motor / generator 5 can share and generate power as a driving force of the entire vehicle.

  An intake passage 11 and an exhaust passage 12 are connected to each cylinder 10 of the engine 3. The intake passage 11 includes an intake manifold 11 a that distributes intake air to each cylinder 10, and the exhaust passage 12 includes an exhaust manifold 12 a that collects exhaust from each cylinder 10. The intake passage 11 is provided with an air cleaner 13 for air filtration, a throttle valve 14 capable of adjusting the air flow rate, a compressor 15 a of a turbocharger 15, and an intercooler 16. The exhaust passage 12 is provided with a turbine 15b of the turbocharger 15, a start catalyst 17 that mainly purifies exhaust when cold, and an exhaust purification catalyst 18 that purifies harmful components in the exhaust.

  The engine 3 is provided with an EGR device 20 that recirculates part of the exhaust gas to the intake system. The EGR device 20 includes an EGR passage 21 that connects the exhaust passage 12 and the intake passage 11, an EGR cooler 22 that cools the exhaust led to the EGR passage 21, and an EGR valve 23 that adjusts the flow rate of EGR gas. . One end of the exhaust side of the EGR passage 21 is connected to the exhaust passage 12 between the start catalyst 17 and the NOx catalyst 18, and one end of the intake side is connected to the intake passage between the throttle valve 14 and the compressor 15a of the turbocharger 15. 11 is connected.

  The engine 3 and the first motor / generator 4 are connected to a power split mechanism 6 which is a differential mechanism. The output of the power split mechanism 6 is transmitted to the output gear 30. The output gear 30 and the second motor / generator 5 are connected to each other and rotate together. The power output from the output gear 30 is transmitted to the drive wheels 33 via the speed reducer 31 and the differential device 32. The first motor / generator 4 has a stator 4a and a rotor 4b. The first motor / generator 4 functions as a generator that generates power by receiving the power of the 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 includes a stator 5a and a rotor 5b, and functions as an electric motor and a generator, respectively. Each motor / generator 4, 5 is connected to a battery 36 as a power storage means via a motor control device 35. A well-known capacitor can be provided in place of the battery 36. The motor control device 35 converts the electric power generated by the motor / generators 4 and 5 into direct current and stores it in the battery 36, and converts the electric power of the battery 36 into alternating current and supplies it to the motor / generator 4 and 5.

  The power split mechanism 6 is configured as a single-pinion type planetary gear mechanism, and has a planetary carrier C that holds a sun gear S, a ring gear R, and a pinion P meshing with these gears S and R in a state capable of rotating and revolving. And have. The sun gear S is connected to the rotor 4 a of the first motor / generator 4, the ring gear R is connected to the output gear 30, and the planetary carrier C is connected to the crankshaft 7 of the engine 3. A damper 8 is interposed between the crankshaft 7 and the planetary carrier C, and the damper 8 absorbs torque fluctuations of the engine 3.

  Control of the vehicle 1 is controlled by an electronic control unit (ECU) 40. The ECU 40 performs various controls on the engine 3 and the motor generators 4 and 5. Hereinafter, main control performed by the ECU 40 in relation to the present invention will be described. The ECU 40 receives signals from a large number of sensors. As an example related to the present invention, an accelerator opening sensor 41 that outputs a signal corresponding to a depression amount (accelerator opening) of an accelerator pedal (not shown), A vehicle speed sensor 42 that outputs a signal according to the speed (vehicle speed) of the vehicle 1, an SOC sensor 43 that outputs a signal according to the storage rate of the battery 36, and a crank angle sensor that outputs a signal according to the engine speed of the engine 3 44 and each signal of the in-cylinder temperature sensor 45 that outputs a signal corresponding to the temperature in the combustion chamber of the engine 3 are input to the ECU 40.

  The ECU 40 refers to the output signal of the accelerator opening sensor 41 and the output signal of the vehicle speed sensor 42 to calculate the required output requested by the driver to the vehicle 1 so that the system efficiency for the required output is optimized. The vehicle 1 is controlled while switching various modes. For example, in the low load region where the thermal efficiency of the engine 3 is reduced, the EV mode in which the combustion of the engine 3 is stopped and the second motor / generator 5 is driven is selected. When the torque is insufficient with only the engine 3, the hybrid mode is selected in which the engine 3 and the second motor / generator 5 are used as a driving source for traveling.

  When the hybrid mode is selected, the required output for the entire vehicle 1 is equal to the sum of the required engine output of the engine 3 and the required motor output of the second motor / generator 5. That is, when the required output for the entire vehicle 1 cannot be covered only by the output of the engine 3, the shortage is compensated by the output of the second motor / generator 5. The distribution of the engine request output and the motor request output with respect to the request output changes according to the change in the operating point of the engine 3 defined by the engine speed and the engine torque. When the engine request output is specified, the operating point of the engine 3 that can realize the engine request output is determined. Unless the special condition is satisfied, the operating point of the engine 3 is controlled so as to move on the preset optimum fuel consumption line L (see FIG. 2). Is set on the optimum fuel consumption line L. The optimum fuel consumption line L is determined by adaptation using an actual machine or a simulation so that the thermal efficiency of the engine 3 is optimized.

  Here, an outline of the control of the present embodiment performed by the ECU 40 as the output control device will be described with reference to FIGS. 2 and 3. In general, the lower the combustion chamber temperature of the internal combustion engine, the worse the PN value in the exhaust operated with the same fuel injection amount (engine torque). Therefore, the ECU 40 sets an engine torque limit value according to the combustion chamber temperature of the engine 3 so that deterioration of the PN value can be suppressed. The engine torque limit value is set so that the engine torque limit value decreases as the combustion chamber temperature decreases, in other words, the engine torque limit value increases as the combustion chamber temperature increases.

  As shown in FIG. 2, when the engine torque of the engine output B based on the engine required output exceeds the engine torque limit value A, the engine required output cannot be achieved while maintaining the engine operating point on the optimum fuel consumption line L (operation (See point F '). Therefore, the operating point of the engine 3 is changed from the operating point F ′ on the optimum fuel consumption line L so as to approach the engine required output without exceeding the engine torque limit value A, and the motor output of the second motor / generator 5 Compensate for insufficient output until engine output is reached. However, since the motor output that can be output from the second motor / generator 5 is restricted by the input / output restriction of the battery 36, the shortage of the engine output cannot be compensated unconditionally. That is, the output assistance by the second motor / generator 5 is limited to the input / output restriction range of the battery 36.

  As shown in FIG. 3, there is a lower limit value defined by input / output restrictions on the storage rate as a representative value of the state of charge (SOC) of the battery 36. Therefore, the ECU 40 brings the engine operating point closer to the engine required output within a range that does not exceed the lower limit value of the storage rate of the battery 36. In the example shown in FIGS. 2 and 3, even if the battery moves from the point F ′ to the point G, it does not fall below the lower limit value of the storage rate. The required engine output can be achieved by moving from the point 'to the point G. The vertical axis in FIG. 2 indicates the difference from the engine required output, but when the G point and the F ′ point are in the positional relationship in FIG. 1, the vertical axis in FIG. 2 is the engine speed difference. You can also.

  In order to realize the above control, the ECU 40 executes the control routine of FIG. The program of the control routine of FIG. 4 is stored in the ECU 40, and is read out in a timely manner and executed when the temperature in the combustion chamber is less than a predetermined value corresponding to the cold state.

  The ECU 40 determines whether or not there is a stop request for the engine 3 in step S1 after the engine 3 is started in response to a predetermined start request in step S0. If there is a stop request, the process proceeds to step S13, the stop process for the engine 3 is performed, the engine 3 is stopped, and the routine is exited. On the other hand, if there is no stop request, the process proceeds to step S2.

  In step S2, the ECU 40 calculates the engine required output B based on the accelerator opening and the vehicle speed. The accelerator opening is acquired based on the output signal of the accelerator opening sensor 41, and the vehicle speed is acquired based on the output signal of the vehicle speed sensor 42, respectively. In step S3, the ECU 40 sets the engine torque limit value A based on the combustion chamber temperature. The engine torque limit value A is for limiting the engine torque of the engine 3, and is set based on a calculation map (not shown) so as to increase as the temperature in the combustion chamber increases.

  In this calculation map, an engine torque limit value A at which the PN value can be suppressed within an allowable range is set for each temperature in the combustion chamber. Therefore, it is compensated that the PN value is suppressed within the allowable range by the ECU 40 setting the engine torque limit value A based on this calculation map. The combustion chamber temperature is acquired based on the output signal of the in-cylinder temperature sensor 45. Instead of acquiring the combustion chamber temperature by the in-cylinder temperature sensor 45, the cooling water temperature, the intermittent time, the engine work after the start, etc. It is also possible to estimate and obtain the combustion chamber temperature based on the physical quantity correlated with the combustion chamber temperature.

  In step S4, the ECU 40 calculates the torque B ′ on the optimum fuel consumption line L (see FIG. 2) based on the engine required output B calculated in step S2. In step S5, the ECU 40 determines whether or not the torque B 'is larger than the engine torque limit value A. If the torque B 'is greater than the engine torque limit value A, the process proceeds to step S6. If not, the subsequent process is skipped and the process returns to step S1.

  In step S6, the ECU 40 temporarily sets an output F ′ (see FIG. 2) corresponding to the intersection of the optimum fuel consumption line L and the engine torque limit value A. In step S <b> 7, the ECU 40 refers to the output signal of the SOC sensor 43 and acquires the storage rate of the battery 36. In step S8, the ECU 40 calculates a tolerance C (see FIG. 3) between the engine output and the engine request output based on the storage rate obtained in step S7. If the change amount of the operating point of the engine 3 is equal to or smaller than the tolerance C, it is compensated that the output assist by the second motor / generator 5 is not less than the lower limit value of the battery 36 when the operating point is changed. Is done. That is, the storage rate of the battery 36 is maintained at the lower limit value or more. This lower limit corresponds to a predetermined value according to the present invention.

  In step S9, the ECU 40 calculates an additional output G to be added to the engine output in the current calculation. The additional output G is calculated by subtracting the operating point F ′ set in step S6 and the tolerance C calculated in step S8 from the engine required output B.

  In step S <b> 10, the ECU 40 calculates an engine instruction output F that is an output command value for the engine 3. The engine instruction output F is calculated by adding the output addition G calculated in step S9 to the output F ′ set in step S6.

  In step S11, the ECU 40 calculates an engine speed E that is a control target based on the engine instruction output F and the engine torque limit value A calculated in step S10. In step S12, the ECU 40 changes the first motor / generator 4 connected to the power split mechanism 6 so that the operating point of the engine 3 is changed to the engine operating point that is the engine torque limit value A and the engine speed E. Control. Then, the process returns to step S1.

  According to the above control routine, output control is performed so that the engine torque limit value is not exceeded and the power storage rate is maintained at or above the lower limit value. Thereby, the deterioration of the PN value accompanying the increase in the torque of the engine 3 can be suppressed, and the deterioration of the PN value due to the extra output increase of the engine 3 due to the decrease in the storage rate of the battery 36 can also be suppressed. The ECU 40 functions as setting means according to the present invention by executing step S3 of the control routine of FIG. 4, and functions as control means according to the present invention by executing steps S4 to S12.

  The present invention can be implemented in various forms without being limited to the above forms. In the above embodiment, an engine with a supercharger is used as the internal combustion engine mounted on the vehicle. However, the output control device of the present invention may be applied to a hybrid vehicle mounted with a naturally aspirated engine.

  Further, the scope of application of the present invention is not limited to the configuration of the illustrated driving device. The illustrated form is a so-called series-parallel type hybrid vehicle, but the output control device of the present invention can also be applied to a parallel type hybrid vehicle. In the illustrated embodiment, an electric continuously variable transmission is configured by connecting the first motor / generator 5 and the engine 3 to the power split mechanism 6, but the operating point of the internal combustion engine can be arbitrarily set. The form of the driving device is not limited as long as it can be changed. For example, the present invention can be applied to a hybrid vehicle in which a continuously variable transmission such as a belt type is mounted and the engine output is assisted by a single electric motor.

1 Vehicle 3 Engine (Internal combustion engine)
5 Second motor / generator (electric motor)
36 battery (electric storage means)
40 ECU (setting means, control means)

Claims (1)

An electric storage provided with an internal combustion engine and an electric motor as a driving source for traveling, both of the internal combustion engine and the electric motor can share and generate power as a driving force of the entire vehicle, and is used for driving the electric motor A hybrid vehicle output control device applied to a hybrid vehicle provided with means,
Setting means for setting an engine torque limit value of the internal combustion engine according to the temperature in the combustion chamber when the temperature in the combustion chamber of the internal combustion engine is less than a predetermined value;
When it is determined that the engine required output for the internal combustion engine exceeds the engine torque limit value, the power storage ratio of the power storage means can be maintained at a predetermined value or more, and the engine request output is within a range not exceeding the engine torque limit value. Control means for changing the engine speed of the internal combustion engine so as to approach
An output control device for a hybrid vehicle, comprising:

Images