JP2020032754A - Hybrid vehicle - Google Patents

Abstract

To avoid ammonia slip when engine load transiently increases.SOLUTION: A hybrid vehicle H includes an internal combustion engine 1 and a motor generator M as power sources. The hybrid vehicle includes: a selective reduction type NOx catalyst 24 provided in an exhaust passage 12 of the internal combustion engine; and a correction unit 100 for correcting the output from the motor generator on an increase side when the load of the internal combustion engine transiently increases.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a hybrid vehicle, and more particularly, to a hybrid vehicle including an internal combustion engine and a motor generator as power sources.

  In a hybrid vehicle, when the internal combustion engine is operated at a lean air-fuel ratio, particularly a diesel engine, a selective reduction type NOx catalyst (so-called SCR: Selective Catalytic Reduction) for reducing and purifying nitrogen oxides (NOx) in exhaust gas. May be provided in the exhaust passage.

  In the case of such a hybrid vehicle, by making the motor generator function as a generator, it is possible to increase the load on the engine, increase the exhaust gas temperature, and increase the catalyst temperature of the NOx catalyst (for example, see Patent Document 1). .

JP 2014-227888 A

  By the way, the NOx catalyst has the ability to adsorb ammonia, and exhibits higher NOx purification performance as more ammonia is adsorbed. On the other hand, the ammonia adsorption ability of the NOx catalyst changes depending on the catalyst temperature, and the higher the catalyst temperature, the lower the upper limit of the ammonia adsorption amount that the NOx catalyst can adsorb.

  When the load on the engine transiently increases, for example, during acceleration of the vehicle, the catalyst temperature sharply rises. After this temperature rise, the amount of ammonia already adsorbed on the NOx catalyst may exceed the upper limit and be desorbed and released from the NOx catalyst. This desorption is called an ammonia slip.

  When the ammonia slip occurs, a relatively large amount of ammonia is discharged downstream of the NOx catalyst, and may be released to the atmosphere. Therefore, it is desirable to avoid ammonia slip as much as possible.

  Therefore, the present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a hybrid vehicle capable of avoiding ammonia slip when the load of the engine transiently increases.

According to one aspect of the present disclosure,
A hybrid vehicle including an internal combustion engine and a motor generator as power sources,
A selective reduction type NOx catalyst provided in an exhaust passage of the internal combustion engine,
When the load of the internal combustion engine transiently increases, a correction unit that corrects the output of the motor generator to an increasing side,
And a hybrid vehicle comprising:

Preferably, the hybrid vehicle further includes a prediction unit that predicts a future temperature of the NOx catalyst based on an operation state of the internal combustion engine,
The correction unit sets a target temperature range of the NOx catalyst, and corrects the output of the motor generator to an increasing side when a future temperature of the NOx catalyst predicted by the prediction unit is higher than the target temperature range. .

Preferably, the hybrid vehicle further includes an acquisition unit configured to acquire a current temperature of the NOx catalyst,
The correction unit increases the output of the motor generator when the current temperature acquired by the acquisition unit is within the target temperature range, and the future temperature predicted by the prediction unit is higher than the target temperature range. To be corrected.

  Preferably, the correction unit calculates an output correction value of the motor generator based on a difference between a future temperature predicted by the prediction unit and a target temperature within the target temperature range.

  Preferably, when correcting the output of the motor generator to an increasing side, the correcting unit corrects the output of the internal combustion engine to a decreasing side.

  According to the present disclosure, it is possible to avoid ammonia slip when the load on the engine transiently increases.

FIG. 1 is a schematic diagram illustrating a configuration of a hybrid vehicle. 5 is a graph showing ammonia adsorption characteristics of a NOx catalyst. 5 is a time chart showing changes in the catalyst temperature of the NOx catalyst. It is a figure showing various maps. 5 is a flowchart illustrating a control routine according to the embodiment. 5 is a graph showing a state of output correction of an engine and a motor generator.

  Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be noted that the present disclosure is not limited to the following embodiments.

  FIG. 1 shows a hybrid vehicle according to the present embodiment. The hybrid vehicle (simply referred to as a vehicle) H includes an internal combustion engine (also referred to as an engine) 1 and a motor generator (simply referred to as a motor) M as power sources, and is configured as a parallel hybrid vehicle. In the present embodiment, the vehicle H is a large vehicle such as a truck, and the engine 1 is an internal combustion engine operated at a lean air-fuel ratio, specifically, a diesel engine. However, there is no particular limitation on the types, types, uses, and the like of the vehicle H and the engine 1. For example, the vehicle H may be a small vehicle such as a passenger car, or the engine 1 may be a gasoline engine. The left side of the figure is the vehicle front, and the right side is the vehicle rear.

  Regarding the drive system of the vehicle H, an output shaft (crankshaft) of the engine 1 is connected to an automatic transmission 4 via a fluid coupling 2 such as a torque converter and an automatic clutch 3. The automatic clutch 3 includes a friction clutch and a clutch actuator for connecting and disconnecting the friction clutch. The clutch actuator is controlled by an electronic control unit (ECU) 100 mounted on the vehicle, so that the friction clutch is connected and disconnected. Controlled. The fluid coupling 2 includes a lock-up clutch, and the lock-up clutch is also controlled by the ECU 100 to connect and disconnect. The automatic transmission 4 of the present embodiment is a so-called automated manual transmission (AMT: Automated Manual Transmission), and includes a manual transmission and a shift actuator that operates the manual transmission. The shift operation of the manual transmission is performed by the shift actuator being controlled by the ECU 100.

  The output shaft of the automatic transmission 4 is connected to left and right wheels 8L, 8R via a propeller shaft 5, a differential device 6, and left and right axles 7L, 7R. Although the configuration of a front engine rear drive (FR) vehicle with a vertical engine is shown here, the engine may be horizontal, and the vehicle may be a front engine front drive (FF) vehicle, a mid engine rear drive (FR) The automatic transmission 4 may have a PTO (Power Take-Off) shaft 9, and a motor M may be mounted on the PTO shaft 9. It is connected. Thereby, the motor M can transmit the driving force to and from the automatic transmission 4. The motor M is electrically connected to the battery 11 via the inverter 10. When the inverter 10 is controlled by the ECU 100, the output of the motor M is controlled.

  In the exhaust passage 12 of the engine 1, an oxidation catalyst 22, a filter 23, a selective reduction type NOx catalyst (hereinafter, referred to as NOx catalyst) 24, and an ammonia oxidation catalyst 26 are provided in this order from the upstream side. Each of these constitutes a post-processing member that executes the exhaust post-processing. In the exhaust passage 12 downstream of the filter 23 and upstream of the NOx catalyst 24, a urea injector 25 as a reducing agent injection valve for injecting urea water as a reducing agent is provided.

  The oxidation catalyst 22 oxidizes and purifies unburned components (hydrocarbon HC and carbon monoxide CO) in the exhaust gas, and heats and raises the temperature of the exhaust gas by reaction heat at this time. The filter 23 is a so-called continuous regeneration type diesel particulate filter, and collects particulate matter (PM: Particulate Matter) contained in exhaust gas and burns and removes the collected PM. As the filter 23, a so-called wall flow type filter in which openings at both ends of a honeycomb structure base material are alternately closed in a checkered pattern is used.

The NOx catalyst 24 reacts ammonia obtained by hydrolyzing the urea water injected from the urea injector 25 with NOx in the exhaust gas to reduce and purify NOx. The NOx catalyst 24 is obtained by carrying a transition metal such as 7Cu on a surface of a substrate such as zeolite or alumina by ion exchange, and a titania / vanadium catalyst (V ₂ O ₅ / WO ₃ / TiO ₂ ) on the surface of the substrate. Can be exemplified. The ammonia oxidation catalyst 26 oxidizes and purifies excess ammonia discharged from the NOx catalyst 24.

  The ECU 100 forms a control unit, a circuit element (circuitry), or a controller, and controls the entire vehicle. The ECU 100 includes a CPU (Central Processing Unit) having an arithmetic function, ROM (Read Only Memory) and RAM (Random Access Memory) as storage media, input / output ports, and storage devices other than ROM and RAM. The ECU 100 is configured to control the engine 1, the urea injector 25, the motor M, the inverter 10, the automatic clutch 3 (specifically, a clutch actuator), the lock-up clutch of the fluid coupling 2, and the shift actuator of the automatic transmission 4. Has been programmed.

  The ECU 100 includes a rotation speed sensor 40 for detecting a rotation speed of the engine, specifically, a rotation speed per minute (rpm), an accelerator opening sensor 41 for detecting an accelerator opening, and a NOx catalyst. An upstream exhaust temperature sensor 42 for detecting the temperature of the upstream exhaust flowing into the NOx catalyst 24 and a downstream exhaust temperature sensor 43 for detecting the temperature of the downstream exhaust flowing out of the NOx catalyst 24 are connected. The ECU 100 estimates the catalyst temperature of the NOx catalyst 24 based on the exhaust temperatures detected by the upstream exhaust temperature sensor 42 and the downstream exhaust temperature sensor 43, respectively. However, the method of estimating the catalyst temperature is arbitrary including a known method. Further, a temperature sensor may be provided on the NOx catalyst 24 to directly detect the catalyst temperature. These estimation and detection are collectively called acquisition. It should be noted that the engine speed and the accelerator opening are engine parameters representing the engine operating state.

  The ECU 100 includes an upstream NOx sensor 47 for detecting NOx of upstream exhaust flowing into the NOx catalyst 24, and a downstream NOx sensor 48 for detecting NOx of downstream exhaust flowing out of the NOx catalyst 24. Is connected. These NOx sensors 47 and 48 generate outputs correlated with the NOx concentration of the exhaust gas. The NOx concentration of the upstream exhaust may be estimated based on the engine operating state.

  The ECU 100 is connected to a vehicle speed sensor 44 for detecting the speed (vehicle speed) of the vehicle and a gear position sensor 45 for detecting the gear position (first speed, second speed, etc.) of the automatic transmission 4. . The vehicle speed and the gear position are vehicle parameters representing the vehicle driving state.

  Next, the contents of the control executed by the ECU 100 will be described.

  As described above, the NOx catalyst 24 has an ammonia adsorbing ability, and reacts the ammonia adsorbed by itself with NOx to perform reduction purification of NOx. Also, as the amount of ammonia adsorbed by the NOx catalyst 24 increases, the NOx catalyst 24 exhibits a higher NOx purification performance, and the NOx purification rate of the NOx catalyst 24 tends to increase. Therefore, in the present embodiment, the ECU 100 performs adsorption amount control (also referred to as storage control) for controlling the amount of ammonia adsorbed by the NOx catalyst 24 so that the NOx catalyst 24 adsorbs as much ammonia as possible.

  FIG. 2 shows the ammonia adsorption characteristics of the NOx catalyst 24. The line a indicates the upper limit value Wmax or the adsorption limit of the ammonia adsorption amount W obtained through experiments and the like, and the upper limit value tends to decrease as the catalyst temperature Tc of the NOx catalyst 24 increases. If ammonia is further supplied when the actual amount of adsorbed ammonia is at the upper limit, the ammonia cannot be adsorbed on the NOx catalyst 24, and flows out downstream of the NOx catalyst 24 to cause ammonia slip.

  On the other hand, a target value on the low adsorption amount side by a predetermined margin from the line a is determined as a line b, and the line b is stored in the ECU 100 in the form of a map (may be a function; the same applies hereinafter). This target value is called a target adsorption amount Wt.

  The ECU 100 estimates the catalyst temperature Tc of the NOx catalyst 24 based on the detection values of the exhaust gas temperature sensors 42 and 43. Then, the target adsorption amount Wt corresponding to the estimated catalyst temperature (for example, Tc1 in FIG. 2) is calculated from the map.

  On the other hand, the ECU 100 constantly estimates the ammonia adsorption amount of the NOx catalyst 24. As the estimation method, various methods including a known method can be adopted. In the present embodiment, a mathematical model is constructed based on a chemical reaction formula representing the reaction between ammonia and NOx in the NOx catalyst 24, and the amount of ammonia adsorbed is accurately estimated by the ECU 100 based on the model. At this time, the ECU 100 determines parameters such as the urea water injection amount M from the urea injector 25, the catalyst temperature Tc of the NOx catalyst 24, the exhaust flow rate, the detection values of the upstream and downstream NOx sensors 47 and 48, the engine speed, the fuel injection amount and the like. Is used to estimate the amount of adsorbed ammonia. The ammonia adsorption amount thus estimated is referred to as an estimated adsorption amount We.

  Next, the ECU 100 controls the urea water injection amount M from the urea injector 25 based on the difference ΔW between the target adsorption amount Wt and the estimated adsorption amount We, thereby bringing the estimated adsorption amount We closer to the target adsorption amount Wt.

  Specifically, the ECU 100 obtains the difference ΔW between the target suction amount Wt and the estimated suction amount We by using the formula: ΔW = Wt−We. For example, when the estimated amount of adsorption We is smaller than the target amount of adsorption Wt, as at point d in FIG. 2, the difference ΔW is positive. For this reason, the ECU 100 adds the positive correction injection amount corresponding to the positive difference ΔW to the base injection amount necessary for the reduction of NOx flowing into the NOx catalyst 24, and corrects the urea water injection amount M to the increasing side. As a result, the estimated adsorption amount We increases and approaches the target adsorption amount Wt. The base injection amount is separately calculated by the ECU 100 based on the NOx concentration detected by the upstream NOx sensor 47.

  On the other hand, when the estimated amount of adsorption We is larger than the target amount of adsorption Wt, for example, as at point e in FIG. 2, the difference ΔW is negative. For this reason, the ECU 100 corrects the urea water injection amount M to the decreasing side by adding zero or a negative correction injection amount according to the negative difference ΔW to the base injection amount. As a result, the ammonia adsorbed on the NOx catalyst 24 is consumed for NOx reduction, and the estimated adsorption amount We decreases to approach the target adsorption amount Wt.

  By the way, when the load of the engine transiently increases, for example, when the vehicle is accelerating, the exhaust gas temperature rises sharply, and the catalyst temperature of the NOx catalyst 24 sharply rises accordingly. After this temperature rise, the ammonia adsorption amount of the NOx catalyst 24 may exceed the upper limit value, and an ammonia slip in which a relatively large amount of ammonia is desorbed and released from the NOx catalyst 24 may occur.

  For example, as shown in FIG. 2, it is assumed that the catalyst temperature is Tc1 and the ammonia adsorption amount is W1 at a point c before the engine load is increased. From this state, when the load of the engine transiently increases and the catalyst temperature rises sharply to Tc2, the point c shifts to the point c ′, the ammonia adsorption amount W1 exceeds the upper limit value Wmax, and the difference dW = An amount of ammonia equal to W1-Wmax is released from the NOx catalyst 24.

  Ammonia slip should be avoided as much as possible, as relatively large amounts of ammonia may be released into the atmosphere when they occur.

  Therefore, in the present embodiment, in such a case, the output of the motor M is corrected to increase. Then, an increase in the engine load can be suppressed by the correction amount, and a rise in the exhaust gas temperature and, consequently, a rise in the catalyst temperature can be suppressed. For example, as shown in FIG. 2, the point c before the increase in the engine load can be shifted to the point c ″ after the increase in the engine load so as not to exceed the upper limit value Wmax. Therefore, it is possible to prevent the ammonia slip from occurring, and it is possible to avoid the ammonia slip.

  More specifically, ECU 100 performs control as follows.

  As shown in FIG. 3, the ECU 100 first sets a target temperature range RT that is a catalyst temperature range of the NOx catalyst 24 that is optimal for the current engine operating state and the vehicle operating state. The target temperature range RT is a temperature range that is equal to or higher than the lower limit temperature TL and equal to or lower than the upper limit temperature TH. The target temperature range RT is stored in advance based on the ammonia adsorption characteristic as shown in FIG. 2, the NOx purification characteristic which is a relationship between the catalyst temperature of the NOx catalyst 24 and the NOx purification rate, the current estimated adsorption amount We, and the like. The program is set by the ECU 100 according to the executed program. The target temperature range RT is set as a temperature range in which no ammonia slip occurs and a NOx purification rate equal to or higher than a predetermined minimum allowable value can be secured.

  Next, the ECU 100 predicts the future temperature Tce of the NOx catalyst 24 based on the engine operating state. That is, as shown in FIG. 3, for example, when a transient increase in the engine load occurs at time t1, the catalyst temperature rises as shown by a broken line. The final value of the catalyst temperature that is expected to finally reach after this rise is the future temperature Tce.

  The ECU 100 calculates the future temperature Tce based on the detected engine speed Ne and the accelerator opening Ac according to a prediction map stored in advance as shown in FIG. When a transient increase in the engine load occurs, the accelerator opening Ac transiently increases from Ac1 to Ac2, for example, as shown in FIG. On the other hand, the relationship between the engine speed Ne, the accelerator opening Ac, and the catalyst temperature acquired during the steady operation through the actual machine test is input to the prediction map. Therefore, by obtaining the catalyst temperature corresponding to the detected engine speed Ne and the accelerator opening Ac from the prediction map, it is possible to predict the future temperature Tce that will eventually reach.

  Note that the future temperature Tce may be predicted based on other parameters such as the vehicle speed in consideration of the influence of the traveling wind and the like.

  If the future temperature Tce is within the target temperature range RT, there is no problem since ammonia slip does not occur and a NOx purification rate equal to or higher than the minimum allowable value can be secured. However, as shown by the broken line in FIG. 3, when the future temperature Tce exceeds the upper limit temperature TH and becomes higher than the target temperature range RT, ammonia slip may occur, and it is necessary to avoid this.

  Therefore, when the future temperature Tce is higher than the target temperature range RT, the ECU 100 corrects the output of the motor M to the increasing side. This makes it possible to avoid ammonia slip, as described above.

  At the time of this correction, the ECU 100 sets a target temperature Ttrg, which is one point in the target temperature range RT. The setting method of the target temperature Ttrg is arbitrary, and may be, for example, an intermediate value (TL + TH) / 2 between the lower limit temperature TL and the upper limit temperature TH, but is not limited thereto. It may be another value during the temperature TH, or may be equal to the upper limit temperature TH or the lower limit temperature TL. An example of the target temperature Ttrg is shown in FIG. 3 for reference.

  Next, the ECU 100 calculates a temperature difference ΔT (= Tce−Ttrg) which is a difference between the future temperature Tce and the target temperature Ttrg, and calculates an output correction amount of the motor M based on the temperature difference ΔT. The output correction amount is a positive correction amount that increases the motor output corresponding to the positive temperature difference ΔT. By correcting the motor output to the increasing side in accordance with the output correction amount, the current temperature Tc (shown by a solid line) of the NOx catalyst 24 can be kept within the target temperature range RT as shown in FIG. Slip can be reliably avoided.

  In particular, in the present embodiment, the future temperature Tce of the NOx catalyst 24 is predicted, and when the predicted future temperature Tce is higher than the target temperature range RT, the motor output is corrected to the increasing side. Before the temperature exceeds the target temperature range RT, a measure to suppress the temperature rise of the NOx catalyst 24 can be taken earlier, and ammonia slip can be reliably avoided.

  In the present embodiment, when the output of the motor M is corrected to the increasing side, the output of the engine 1 is also corrected to the decreasing side. As a result, it is possible to further suppress an increase in the exhaust gas temperature and hence the catalyst temperature, and it is possible to more reliably avoid ammonia slip.

  When the correction is performed as in the present embodiment, the catalyst temperature of the NOx catalyst 24 can be precisely controlled so as to avoid the ammonia slip, as compared with the case where the correction is not performed. Therefore, as shown by the dashed-dotted line f in FIG. 2, the target value Wt can be made closer to the upper limit value Wmax to reduce the margin between the two. Thereby, the practical ammonia adsorption amount of the NOx catalyst 24 can be increased, and the NOx purification performance of the NOx catalyst 24 can be improved.

  Next, a control routine according to the present embodiment will be described with reference to FIG. The illustrated routine is repeatedly executed by the ECU 100 every predetermined calculation cycle τ (for example, 10 msec).

  First, in step S101, the ECU 100 determines the engine speed Ne detected by the rotation speed sensor 40, the accelerator opening Ac detected by the accelerator opening sensor 41, the vehicle speed V detected by the vehicle speed sensor 44, and the gear position. The gear position Gp detected by the sensor 45 and the current temperature Tc of the NOx catalyst 24 estimated based on the detection values of the upstream exhaust temperature sensor 42 and the downstream exhaust temperature sensor 43 are acquired.

  Next, in step S102, the ECU 100, based on the acquired engine speed Ne, the accelerator opening Ac, the vehicle speed V, and the gear position Gp, obtains an engine output demand value which is a reference output demand value used in the base normal control. Pe and the required motor output value Pm are calculated from a predetermined map or the like.

  Next, in step S103, the ECU 100 sets the target temperature range RT and determines whether or not the acquired current temperature Tc of the NOx catalyst 24 is within the target temperature range RT, that is, the temperature is equal to or higher than the lower limit temperature TL and equal to or lower than the upper limit temperature TH. Determine if it is a value. If it is determined that the current temperature Tc is outside the target temperature range RT, the process proceeds to step S108 (details will be described later).

  On the other hand, if the ECU 100 determines that the current temperature Tc is within the target temperature range RT, the ECU 100 proceeds to step S104, and calculates the future temperature Tce of the NOx catalyst 24 from the map of FIG. Next, in step S105, the ECU 100 determines whether or not the future temperature Tce is higher than the upper limit temperature TH of the target temperature range RT.

  If it is determined that the temperature is higher than the upper limit temperature TH, the ECU 100 proceeds to step S106, and calculates a temperature difference ΔT (= Tce−Ttrg) between the future temperature Tce and the target temperature Ttrg. Then, an output correction amount ΔP (corresponding to an output correction value in claims) corresponding to the temperature difference ΔT is calculated from the correction amount map shown in FIG. According to the correction amount map, the output correction amount ΔP is zero when the temperature difference ΔT is zero, and the output correction amount ΔP tends to increase as the temperature difference ΔT increases. Here, since the temperature difference ΔT is positive, a positive output correction amount ΔP is calculated.

  Next, in step S107, the ECU 100 corrects the required engine output value Pe and the required motor output value Pm calculated in step S102 based on the output correction amount ΔP. Specifically, the output correction amount ΔP is added to the motor output request value Pm calculated in step S102, and a corrected new motor output request value Pm is calculated. Further, the output correction amount ΔP is subtracted from the engine output required value Pe calculated in step S102, and a corrected new engine output required value Pe is calculated.

  Thereafter, in step S108, the ECU 100 controls the motor M (specifically, the supply current) so that an output equal to the corrected motor output required value Pm is actually generated, and the corrected engine output required value The engine 1 (specifically, the fuel injection amount) is controlled so that an output equal to Pe is actually generated. As a result, the motor output is corrected to increase and the engine output is corrected to decrease, thereby avoiding ammonia slip.

  Here, when the engine load transiently increases, the accelerator opening Ac is transiently increased, and accordingly, the reference engine output demand value Pe and the reference engine output value during normal control calculated in step S102 are added. The required motor output value Pm is increased. For example, as shown in FIG. 6, assuming that the required engine output value before the engine load increase is Pe1 and the required motor output value is Pm1, after the engine load increase, the required engine output value increases by Pe2 corresponding to the load increase. Pe1 + Pm2, and the required motor output value increases by Pm2 corresponding to the load increase to Pm1 + Pm2. In order to satisfy the driver's acceleration request or load increase request, the total output of (Pe1 + Pe2) + (Pm1 + Pm2) must be output from the engine 1 and the motor M.

  However, when the future temperature Tce exceeds the target temperature range RT, when (Pe1 + Pe2) is output from the engine 1 in the same manner as in the normal control, ammonia slip may occur. Therefore, in the present embodiment, a part (or all) of the engine output request value Pe2 corresponding to the increased load is passed to the motor output request value as the output correction amount ΔP, and both output request values are corrected. In other words, while the total output demand value is kept the same as in the normal control, the distribution of the two is changed, and the ratio of the motor output is increased and the ratio of the engine output is reduced as compared with the time of the normal control. As a result, the required engine output value after the load increase and after the correction is Pe1 + Pe2-ΔP, and the required motor output value is Pm1 + Pm2 + ΔP. By doing so, it is possible to suppress an increase in the catalyst temperature and to avoid ammonia slip, while satisfying the driver's acceleration request or load increase request.

  Incidentally, if the motor M is stopped by traveling only by the engine 1 before the engine load is increased, that is, if Pe1> 0 and Pm1 = 0, the required motor output value Pm becomes Pm2 + ΔP after the engine load is increased, The motor M is started. At this time, if Pm2 is zero, the motor M is operated only by the output correction amount ΔP.

  As shown in the example, when a part of the engine output request value Pe2 for the load increase is set to the output correction amount ΔP, that is, when ΔP <Pe2, the engine output request value Pe after the load increase is equal to the value before the load increase. Although it increases from the value (Pe1) to (Pe1 + Pe2-ΔP), the increase can be suppressed more than the value (Pe1 + Pe2) at the time of the normal control, and the increase in the catalyst temperature can be suppressed.

  Although not shown, when all of the engine output required values Pe2 for the load increase are set as the output correction amount ΔP, that is, when ΔP = Pe2, the engine output required value Pe after the load increase is equal to the value before the load increase ( Pe1) is maintained, and the increase can be significantly suppressed as compared with the value (Pe1 + Pe2) at the time of the normal control. Therefore, an increase in the catalyst temperature can be significantly suppressed. In this case, the increase in the engine output required for acceleration is all borne by the motor M.

  As understood from the above description, "correcting the output of the motor generator to the increasing side when the load of the internal combustion engine transiently increases" in the claims and the like means that the load of the internal combustion engine is transient. When the load increases, the reference motor output required value (Pm1 + Pm2) after the load increase in the normal control is corrected to the increasing side, that is, the positive output correction amount ΔP is added to the reference motor output required value (Pm1 + Pm2). This means that the reference motor output request value is corrected. Further, "correcting the output of the internal combustion engine to the decreasing side when correcting the output of the motor generator to the increasing side" in the claims and the like means increasing the reference motor output required value (Pm1 + Pm2) as described above. In addition, when correcting the reference engine output demand value (Pe1 + Pe2) after the load increase during the normal control to the decreasing side, that is, by adding the positive output correction amount ΔP from the reference engine output demand value (Pe1 + Pe2). This means that the reference engine output required value is corrected by subtraction.

  Returning to FIG. 5, when ECU 100 determines in step S105 that future temperature Tce is not higher than upper limit temperature TH, the process proceeds to step S109, and determines whether future temperature Tce is lower than lower limit temperature TL of target temperature range RT. Judge.

  If it is determined that the temperature is lower than the lower limit temperature TL, the ECU 100 proceeds to step S106, and calculates the output correction amount ΔP corresponding to the temperature difference ΔT from the correction amount map shown in FIG. Here, since the temperature difference ΔT is negative, a negative output correction amount ΔP is calculated.

  Next, in step S107, the ECU 100 calculates the corrected motor output required value Pm by adding the output correction amount ΔP to the motor output required value Pm calculated in step S102, as described above. Further, the output correction amount ΔP is subtracted from the engine output required value Pe calculated in step S102 to calculate the corrected engine output required value Pe.

  At this time, since the output correction amount ΔP is negative, the required motor output value Pm is corrected to the decreasing side, and the required engine output value Pe is corrected to the increasing side, so that the correction opposite to the previous case is performed.

  Thereafter, in step S108, the ECU 100 controls the motor M and the engine 1 based on the corrected required motor output value Pm and the required required engine output Pe in the same manner as described above.

  The case where the future temperature Tce is lower than the target temperature range RT and lower than the lower limit temperature TL corresponds to a case where the load of the engine is transiently reduced during deceleration of the vehicle or the like, for example, a case where fuel cut is executed. In this case, the exhaust gas temperature sharply decreases, and accordingly, the catalyst temperature of the NOx catalyst 24 sharply decreases. After this temperature drop, the NOx purification rate may not be able to satisfy the minimum allowable value. In such a case, the NOx purification performance of the NOx catalyst 24 may deteriorate, and the NOx that has not been reduced may flow downstream of the NOx catalyst 24, and the purification performance of the NOx catalyst 24 may decrease.

  Therefore, in the present embodiment, in such a case, the output of the motor M is corrected to a decrease side. Then, the decrease in the engine load can be suppressed by the correction amount, and the decrease in the exhaust gas temperature and hence the catalyst temperature can be suppressed. Therefore, the amount of decrease in the catalyst temperature can be reduced to such a value that no NOx slip occurs, and NOx slip can be avoided.

  The specific method of this correction is as described above. That is, the required motor output value Pm is corrected to decrease, and the required engine output value Pe is corrected to increase.

  If the motor M is stopped by running only on the engine 1 before the engine load is reduced, the required motor output value Pm becomes a negative output correction value ΔP after the engine load is reduced, and the motor M functions as a generator. A negative regenerative output can be generated. This makes it possible to increase the engine load, suppress a decrease in the catalyst temperature, and avoid NOx slip, as compared with the case where no correction is performed.

  Returning to FIG. 5, when the ECU 100 determines in step S109 that the future temperature Tce is not lower than the lower limit temperature TL, the process proceeds to step S108, and the motor output request value Pm calculated in step S102 without correction is performed. Then, the motor M and the engine 1 are controlled as usual based on the required engine output value Pe. In this case, the future temperature Tce is within the target temperature range RT, and it is expected that a preferable catalyst temperature will be maintained for the time being.

  As described above, according to the present embodiment, when the load of the engine 1 is transiently increased, the output of the motor M is corrected to the increased side, so that the temperature rise of the NOx catalyst 24 is suppressed and the ammonia slip is avoided. It is possible to do.

  In the present embodiment, the ECU 100 corresponds to a correction unit, a prediction unit, and an acquisition unit described in the claims.

  Various other embodiments of the present disclosure are possible. For example, in the above embodiment, the vehicle is an automatic vehicle, but the vehicle may be a manual vehicle. The form of the hybrid system is not limited to the above-described embodiment, and various forms are possible.

  The embodiments of the present disclosure are not limited to the above-described embodiments, but include all modifications, applications, and equivalents included in the spirit of the present disclosure defined by the claims. Therefore, the present disclosure should not be construed as limiting, but can be applied to any other technology belonging to the scope of the idea of the present disclosure.

1 internal combustion engine (engine)
12 Exhaust passage 24 NOx catalyst 100 Electronic control unit (ECU)
H Hybrid vehicle M Motor generator

Claims (5)

A hybrid vehicle including an internal combustion engine and a motor generator as power sources,
A selective reduction type NOx catalyst provided in an exhaust passage of the internal combustion engine,
When the load of the internal combustion engine transiently increases, a correction unit that corrects the output of the motor generator to an increasing side,
A hybrid vehicle comprising: A prediction unit that predicts a future temperature of the NOx catalyst based on an operation state of the internal combustion engine,
The correction unit sets a target temperature range of the NOx catalyst, and corrects the output of the motor generator to an increasing side when a future temperature of the NOx catalyst predicted by the prediction unit is higher than the target temperature range. The hybrid vehicle according to claim 1. An acquisition unit that acquires a current temperature of the NOx catalyst,
The correction unit increases the output of the motor generator when the current temperature acquired by the acquisition unit is within the target temperature range, and the future temperature predicted by the prediction unit is higher than the target temperature range. The hybrid vehicle according to claim 2. The hybrid vehicle according to claim 2, wherein the correction unit calculates an output correction value of the motor generator based on a difference between a future temperature predicted by the prediction unit and a target temperature within the target temperature range. The hybrid vehicle according to any one of claims 1 to 4, wherein the correction unit corrects the output of the internal combustion engine to a decrease when correcting the output of the motor generator to an increase.

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