CONTROLLER FOR A MACHINE AND METHOD FOR CONTROLLING A MACHINE

Abstract

Controller for a machine, wherein the machine is installed in a vehicle designed to use heat from a machine coolant to heat a vehicle interior, and wherein the machine includes an exhaust duct containing a filter designed to collect particulate matter from exhaust, wherein the controller comprises: a processing circuit designed to perform a fuel shutdown for filter regeneration by burning the fine dust collected in the filter, and wherein the processing circuit is configured to perform an interrupt operation to interrupt the fuel cut-off in a case where heating of the vehicle interior is requested when the fuel cut-off is performed and an engine coolant temperature, which is a temperature of the engine coolant, becomes lower than or equal to a predetermined temperature after the fuel cut-off is initiated.

Description

Background1. Technical area

[0001] The present invention relates to a controller for a machine and a method for controlling a machine. 2. Description of the state of the art

[0002] A known engine includes a filter arranged in an exhaust duct to collect particulate matter from exhaust gases. JP 2018-90154 A describes an engine including such a filter and implementing filter regeneration control to combust and remove particulate matter collected in the filter by performing a fuel shutoff and supplying oxygen to the filter. Methods and systems for controlling an engine using a controller are also the subject of US 2018 / 0156097 A1 and US 2013 / 0197749 A1.

[0003] A vehicle containing an engine uses the heat of the engine coolant to warm the vehicle interior. Thus, if the engine undergoes fuel cutoff for an extended period during filter regeneration control, combustion will not occur, and the temperature of the engine coolant will be reduced. Thus, the warming cannot continue.

[0004] Based on the prior art, the object of the invention is to provide a technology that ensures the heating of the vehicle interior despite the fuel shutoff during filter regeneration. This object is achieved by the features of the independent claims; advantageous developments are the subject of the subclaims. Summary

[0005] This Summary is provided to introduce a selection of concepts in a simplified form, which are further described below in the Detailed Description. This Summary is neither intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] One aspect of the present invention provides a controller for an engine. The engine is installed in a vehicle and is configured to use heat from an engine coolant to heat a vehicle interior. The engine includes an exhaust duct that includes a filter configured to collect particulate matter from exhaust gases.The controller includes a processing circuit configured to perform a fuel cut for regenerating the filter by burning the particulate matter collected in the filter, and the processing circuit is configured to perform an interruption process for interrupting the fuel cut in a case where heating of the vehicle interior is requested when the fuel cut is performed and an engine coolant temperature, which is a temperature of the engine coolant, becomes lower than or equal to a predetermined temperature after the fuel cut is started.

[0007] When fuel cutoff is performed for filter regeneration, combustion in the engine is stopped and the engine coolant temperature drops. Thus, heating performance may be reduced if fuel cutoff is performed while the vehicle interior is warming up. Fuel cutoff for filter regeneration can be performed when there is a demand for vehicle interior warming up. In this case, the engine controller interrupts fuel cutoff when the engine coolant temperature drops to a fixed value after fuel cutoff is started. Thus, the coolant temperature rises when combustion in the engine restarts. That is, when the engine coolant temperature drops, fuel cutoff is performed intermittently with a break until the engine coolant temperature is restored.This performs fuel shutoff for filter regeneration in a preferential manner during the warming up of the vehicle interior.

[0008] There is a relationship between the degree of reduced heating performance after the fuel cut is started and the amount of decrease in the engine coolant temperature after the fuel cut is started. Thus, the processing circuit may be configured to interrupt the fuel cut in the interruption process in a case where the amount of decrease in the engine coolant temperature becomes greater than or equal to a interruption determination value with the start of the fuel cut.

[0009] Reduced heating performance is more noticeable when the engine coolant temperature is low than when the engine coolant temperature is high, even if the amount of reduction in the engine coolant temperature after the fuel cut is initiated is the same. Thus, the cutoff determination value can be set to a larger value when the engine coolant temperature is high than when the engine coolant temperature is low.

[0010] When the heating performance is sufficiently restored after the fuel cutoff is interrupted, the fuel cutoff may be restarted. Thus, the processing circuit may be configured to perform a restart operation that restarts the fuel cutoff when the engine coolant temperature becomes higher than or equal to a predetermined temperature after the fuel cutoff is interrupted by the interrupt operation.

[0011] There is a relationship between the degree of recovered heating performance after the fuel cutoff is interrupted and the amount of increase in the engine coolant temperature after the fuel cutoff is interrupted. Thus, the processing circuit may be configured to restart the fuel cutoff in the restart process when the amount of decrease or increase in the engine coolant temperature after the fuel cutoff is interrupted by the interruption process becomes greater than or equal to a restart determination value. Furthermore, the restart determination value may be set to a larger value when the engine coolant temperature is low than when the engine coolant temperature is high.

[0012] One aspect of the present invention provides a method for controlling an engine. The engine is installed in a vehicle and is configured to use heat from an engine coolant to heat a vehicle interior, and the engine includes an exhaust passage including a filter configured to collect particulate matter from exhaust gas. The method includes performing a fuel cut to regenerate the filter by burning the particulate matter collected in the filter, and performing an interruption process that interrupts the fuel cut in a case where heating of the vehicle interior is requested when the fuel cut is performed and an engine coolant temperature, which is a temperature of the engine coolant, becomes lower than or equal to a predetermined temperature after the fuel cut is started.

[0013] Further features and aspects will become apparent from the following detailed description, drawings and claims. Short description of the drawings Fig. 1 is a diagram showing the configuration of a controller for an engine according to an embodiment, the structure of the engine to which the controller is applied, and the structure of a drive system of a hybrid vehicle in which the engine is mounted. Fig. 2 is a flowchart showing a flowchart of a controller-initiated Fig. 1 performed filter regeneration control routine. Fig. 3 is a flowchart showing a controller-initiated Fig. 1 shows the fuel cut-off determination routine or F / C determination routine performed. Fig. 4 is a graph showing the relationship between an interrupt determination value and the value used in the F / C determination routine in Fig. 3 used machine coolant temperature. Fig. 5 is a graph showing the relationship between a restart determination value and the value used in the F / C determination routine in Fig. 3 used machine coolant temperature. Fig. 6 is a timing chart showing an example of a fuel cut-off occurring during the filter regeneration control performed by the controller. Fig. 1 is executed.

[0014] Throughout the drawings and detailed description, like reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and representation of elements in the drawings may be exaggerated for clarity, illustration, and simplification. Detailed description

[0015] This description provides a comprehensive understanding of the described methods, devices, and / or systems. Modifications and equivalents of the methods, devices, and / or systems will be apparent to one skilled in the art. Sequences of operations are exemplary and may be changed as would be apparent to one skilled in the art, except for operations that necessarily occur in a particular order. Descriptions of functions and structures that would be familiar to one skilled in the art are omitted.

[0016] Embodiments may take various forms and are not limited to the examples described. However, the examples described are thorough and complete, and will fully convey the scope of the invention to one skilled in the art.

[0017] Now, a controller for a machine according to an embodiment with reference to Fig. 1 to 6. The engine controller in the present embodiment is applied to an engine mounted in a hybrid vehicle.

[0018] As in Fig. 1, a drive source is installed in the hybrid vehicle, and the drive source includes an engine 10 and two motor generators, namely a first motor generator 11 and a second motor generator 12. The first motor generator 11 and the second motor generator 12 each function as an electric motor that is supplied with power to generate power and as a generator that receives an external power to generate power.

[0019] The hybrid vehicle includes a planetary gear mechanism 13 having three rotating elements: a sun gear 13A, a planetary carrier 13B, and a ring gear 13C. In the planetary gear mechanism 13, the sun gear 13A is coupled to the first motor-generator 11, and the planetary carrier 13B is coupled to the engine 10. A counter drive gear 14 is coupled to the ring gear 13C of the planetary gear mechanism 13 and rotates integrally therewith. Furthermore, the counter drive gear 14 meshes with a counter driven gear 15. The second motor-generator 12 is coupled to a reduction gear 16 meshed with the counter driven gear 15. The counter driven gear 15 is further coupled to a final drive gear 17 and rotates integrally therewith. The final drive gear 17 is meshed with a final driven gear 18. The final drive gear 18 is coupled to right and left axle shafts 20 by means of a differential gear 19.

[0020] The engine 10 includes cylinders 21 that combust an air-fuel mixture, an intake passage 22 through which intake air flows into the cylinders 21, and an exhaust passage 23 through which exhaust gas generated by the combustion of the air-fuel mixture in the cylinders 21 flows. The intake passage 22 includes a throttle valve 24 that serves as a valve that regulates the flow rate of intake air in the intake passage 22. The cylinders 21 of the engine 10 each include a fuel injection valve 25 that injects fuel into the intake air and an ignition device 26 that ignites the air-fuel mixture with a spark discharge. A three-way catalyst converter 27 that oxidizes hydrocarbons and carbon monoxide in the exhaust gas and reduces nitrogen oxides in the exhaust gas is arranged in the exhaust passage 23.A filter 28 which collects particulate matter from the exhaust gas is further arranged on a downstream side of the three-way catalyst converter 27 in the exhaust passage 23.

[0021] The structure of a cooling system of the engine 10 will now be described. The engine 10 includes a water jacket 30, which is a water passage through which a coolant flows around the cylinders 21. The engine 10 also includes an inlet 31 through which the coolant flows into the water jacket 30, and an outlet 32 ​​through which the coolant flows out of the water jacket 30. The inlet 31 and the outlet 32 ​​of the water jacket 30 are connected by a radiator passage 33 outside the engine 10. The radiator passage 33 includes a radiator 34 that cools the coolant by exchanging heat with the ambient air. An electronic thermostat 35 and an electric water pump 36 are arranged on a downstream side of the radiator 34 in the radiator passage 33. The cooling system of the machine 10 also includes a heating channel 37 connecting the outlet 32 ​​of the water jacket 30 to a portion between the thermostat 35 and the water pump 36 of the radiator channel 33.The heating duct 37 contains a heater core 38 that exchanges heat with the coolant to heat air sent to the vehicle interior.

[0022] The hybrid vehicle further includes an electronic control unit 40. The electronic control unit 40 includes an arithmetic processing circuit 41 that performs various types of calculations related to vehicle control, and a memory 42 that stores programs and data for vehicle control. The electronic control unit 40 receives information indicative of an operating condition of the engine 10, such as an intake air amount GA, an engine speed NE, and an engine coolant temperature TW, and information indicative of a drivability of the vehicle, such as an accelerator pedal opening degree ACC and a vehicle speed SPD, from various types of sensors arranged in the vehicle. The engine coolant temperature TW represents the temperature of the engine coolant passing through the water jacket 30 and flowing from the drain 32 into the radiator passage 33 or the heater passage 37.Based on such information, the arithmetic processing circuit 41 of the electronic control unit 40 performs various types of control on the hybrid vehicle by reading and executing programs stored in the memory 42. The electronic control unit 40 performs control including regenerative / drive torque control on the first motor generator 11 and the second motor generator 12, air conditioning control inside the vehicle cabin, and engine control. In the present embodiment, the electronic control unit 40, which controls the operation of the engine 10 as a vehicle control routine, corresponds to a controller for an engine.

[0023] In air conditioning control, when the temperature of the vehicle interior is lower than a preset temperature, the electronic control unit 40 heats the air sent to the vehicle interior with the heater core 38 to warm the vehicle interior. The amount of air sent to the vehicle interior is determined based on the difference between the temperature of the vehicle interior and the preset temperature, the ambient temperature, the engine coolant temperature TW, and the like. When the engine coolant temperature TW is low, the air sent to the vehicle interior cannot be sufficiently heated. When the engine coolant temperature TW is lower than or equal to a predetermined temperature TW0 for stopping air supply, the air sent to the vehicle interior is stopped even if heating is requested.

[0024] The electronic control unit 40 estimates the temperature of the filter 28 based on the operating conditions of the engine 10, such as the intake air charging efficiency of the cylinders 21 and the engine speed NE. The temperature of the filter 28 estimated by the electronic control unit 40 is referred to as an estimated filter temperature TF. The electronic control unit 40 estimates the amount of particulate matter collected in the filter 28 based on the engine speed NE, the intake air charging efficiency, the estimated filter temperature TF, and the like. The amount of particulate matter collected in the filter 28 estimated by the electronic control unit 40 is referred to as an estimated PM deposition amount PS. The electronic control unit 40 executes filter regeneration control that prevents the collected particulate matter from clogging the filter 28 based on the estimated PM deposition amount PS as an engine control routine.

[0025] Fig. Figure 2 shows a process routine executed by the electronic control unit 40 in connection with the filter regeneration control. The electronic control unit 40 executes this routine as long as the engine 10 is running.

[0026] The electronic control unit 40 executes this routine in set control cycles. In step S100 of this routine, the electronic control unit 40 determines whether an estimated PM deposition amount PS of the filter 28 is greater than or equal to a predetermined regeneration request determination value P1. If the estimated PM deposition amount PS is determined to be less than the regeneration request determination value P1 (S100: NO), the same determination is made in the next control cycle. The regeneration request determination value P1 is set to a value slightly smaller than the upper limit of the deposition amount of particulate matter in the filter 28 so that the pressure loss of exhaust gas is within a tolerable range at the filter 28.

[0027] In step S100, if it is determined that the estimated PM deposition amount PS is greater than or equal to the regeneration request determination value P1 (S100: YES), the electronic control unit 40 proceeds to step S110. In step S110, the electronic control unit 40 starts a temperature rise process that increases the temperature of the filter 28. The temperature rise process is performed, for example, by increasing a requested output of the engine 10 or the lower limit speed of the engine 10, retarding an ignition timing, or prohibiting intermittent stopping of the engine 10.

[0028] The temperature rise process continues until the electronic control unit 40 determines in step S120 that the estimated filter temperature TF is higher than or equal to the PM combustion temperature, which starts the combustion of the particulate matter in the filter 28. When the estimated filter temperature TF becomes higher than or equal to the PM combustion temperature (S120: YES), the electronic control unit 40 ends the temperature rise process from step S130 and sets an F / C request flag in step S140. The F / C request flag is set to signal that a fuel cut (hereinafter also abbreviated as F / C) of the engine 10 has been requested to regenerate the filter 28, that is, to burn the particulate matter deposited in the filter 28.

[0029] When the F / C request flag is set and an operation of an F / C determination routine described below enables the fuel cut to be performed, the electronic control unit 40 performs the fuel cut to regenerate the filter. When the fuel cut is performed, the electronic control unit 40 stops the injection of fuel from the fuel injection valve 25 and the discharge of sparks from the ignition device 26 in the engine 10. Further, the electronic control unit 40 maintains the rotation of the engine 10 with power generated by the first motor generator 11. In this case, the electronic control unit 40 allows the second motor generator 12 to generate a driving force required for the hybrid vehicle to travel.

[0030] When fuel cutoff is performed in this manner, air drawn into intake passage 22 passes through cylinders 21 and flows into exhaust passage 23. This supplies filter 28 with the oxygen required to combust the particulate matter. The temperature rise process raises the temperature of filter 28 to the temperature required to combust the particulate matter. Thus, fuel cutoff combusts the particulate matter deposited in filter 28.

[0031] Then, in step S150, if the electronic control unit 40 determines that the estimated PM deposition amount PS is less than or equal to a predetermined regeneration completion determination value P2 (S150: YES), the electronic control unit 40 clears the F / C request flag in step S160. Then, the electronic control unit 40 returns to step S100. The regeneration completion determination value P2 is set to a value sufficiently lower than the regeneration request determination value P1.

[0032] Fig. Figure 3 shows a flowchart of an F / C determination routine. The electronic control unit 40 repeatedly executes this routine in set control cycles while the engine 10 is running.

[0033] When this routine starts, the electronic control unit 40 determines whether an F / C request flag is set in step S200. If no F / C request flag is set (S200: NO), the electronic control unit 40 ends the current cycle of the routine.

[0034] If an F / C request flag has been set (S200: YES), the electronic control unit 40 proceeds to step S210. In step S210, the electronic control unit 40 determines whether an F / C request flag was cleared when the routine was executed in the previous cycle. Specifically, the electronic control unit 40 determines whether the filter regeneration control routine has transitioned from a state in which the F / C request flag is cleared to a state in which the F / C request flag is set during a period from the previous cycle of the routine to the current cycle of the routine. If an affirmative determination is made in step S210 (S210: YES), the electronic control unit 40 proceeds to step S250. If a negative determination is made (S210: NO), the electronic control unit 40 proceeds to step S220.

[0035] When the electronic control unit 40 proceeds to step S250, an interruption flag is cleared, and a current engine coolant temperature TW is set as a starting coolant temperature TW1 in step S250. The interruption flag is set to signal a temporary interruption of the fuel cut for filter regeneration. In step S260, the fuel cut for filter regeneration is then permitted. The electronic control unit 40 then ends the current cycle of the routine.

[0036] If a negative determination is made in step S210 (S210: NO), the electronic control unit 40 proceeds to step S220. In step S220, the electronic control unit 40 determines whether there is a request for heating the vehicle interior. If heating has not been requested (S220: NO), the electronic control unit 40 proceeds to step S260 and permits fuel cutoff in step S260. Then, the electronic control unit 40 ends the current cycle of the routine. That is, if the F / C request flag is set, fuel cutoff is permitted as long as there is no heating request.

[0037] If there is a heating request (S220: YES), the electronic control unit 40 proceeds to step S230. In step S230, the electronic control unit 40 determines whether an interrupt flag is set. If an interrupt flag is set (S230: YES), the process proceeds to step S240. If no interrupt flag is set (S230: NO), the process proceeds to step S270.

[0038] If no interruption flag is set (S230: NO), the process proceeds to step S270. In step S270, an interruption determination value T1 is set based on the current engine coolant temperature TW. The interruption determination value T1 is set using an operation map MAP1, which will be described later. The operation map MAP1 is stored in advance in the memory 42. Then, in step S280, the electronic control unit 40 determines whether a difference obtained by subtracting the current engine coolant temperature from the start coolant temperature TW1 (ie, TW1-TW) is greater than or equal to the interruption determination value T1. In the following description, the above-mentioned difference is referred to as the coolant temperature decrease amount following F / C initiation.If the coolant temperature reduction amount following F / C initiation is less than the cut-off determination value T1 (S280: NO), the electronic control unit 40 proceeds to step S260 and permits the fuel cut in step S260. Then, the electronic control unit 40 ends the current cycle of the routine. If the coolant temperature reduction amount following F / C initiation is greater than or equal to the cut-off determination value T1 (S280: YES), the electronic control unit 40 proceeds to step S290. In step S290, the electronic control unit 40 sets the cut-off flag. Furthermore, the electronic control unit 40 sets the current engine coolant temperature TW as a cut-off coolant temperature TW2. In step S290, a restart determination value T2 is set based on the current engine coolant temperature TW.The restart determination value T2 is set using an operation map MAP2, which will be described later. The operation map MAP2 is stored in advance in the memory 42. Then, in step S300, the fuel cut is inhibited. Then, the electronic control unit 40 ends the current cycle of the routine.

[0039] If the cutoff flag is set (S230: YES), the electronic control unit 40 proceeds to step S240. In step S240, the electronic control unit 40 determines whether a difference obtained by subtracting the cutoff coolant temperature TW2 from the current engine coolant temperature TW (ie, TW-TW2) is greater than or equal to the restart determination value T2. The above difference is referred to as the coolant temperature rise amount following an F / C cutoff. If the coolant temperature rise amount following an F / C cutoff is less than the restart determination value T2 (S240: NO), the fuel cutoff is prohibited in step S300. Then, the electronic control unit 40 ends the current cycle of the routine.If the coolant temperature rise amount following an F / C cut is greater than or equal to the restart determination value T2 (S240: YES), the electronic control unit 40 proceeds to step S250. In this case, the electronic control unit 40 clears the cut flag and sets the starting coolant temperature TW1 in step S250, and permits fuel cut in step S260, as described above. Then, the electronic control unit 40 ends the current cycle of the routine.

[0040] Now, the operation and advantages of the present embodiment will be described.

[0041] In filter regeneration control, when the estimated PM deposition amount PS of the filter 28 is greater than or equal to the regeneration request determination value P1 (S100: YES), the temperature rise process for raising the temperature of the filter 28 is started (S110). The temperature rise process continues until the estimated filter temperature TF becomes higher than or equal to the PM combustion temperature (S120: YES). When the temperature rise process ends, the electronic control unit 40 sets the F / C request flag (S140).

[0042] When the F / C determination routine is executed for the first time after the F / C request flag is cleared and set, the electronic control unit 40 proceeds to step S250. In step S250, the electronic control unit 40 clears the cutoff flag and sets the current engine coolant temperature TW as the starting coolant temperature TW1. Then, the electronic control unit 40 permits the fuel cutoff (S260) and starts executing the fuel cutoff on the engine 10.

[0043] If there is no warm-up request during air conditioning control (S220: NO), fuel cut is continuously permitted until the F / C request flag is cleared. Thus, fuel cut continues until the regeneration of filter 28 is completed, when the estimated PM deposition amount PS becomes less than or equal to the regeneration completion determination value P2.

[0044] During fuel cutoff, combustion in the engine 10 is stopped. This lowers the engine coolant temperature TW over time. The heater core 38 performs heat exchange between the coolant and the air sent to the vehicle interior to warm the vehicle interior. Accordingly, if the fuel cutoff for filter regeneration continues for a long period, the engine coolant temperature TW will drop as the vehicle interior heats up. Thus, the vehicle interior may not be sufficiently heated, and the vehicle occupants may feel uncomfortable.

[0045] In the present embodiment, when there is a warm-up request during air conditioning control (S220: YES) and the coolant temperature reduction amount following F / C initiation is greater than or equal to the interruption determination value T1 after fuel cut is started (S280: YES), the interruption flag is set (S290) and fuel cut is prohibited (S300). The coolant temperature reduction amount following F / C initiation is a difference obtained by subtracting the current engine coolant temperature TW from the starting coolant temperature TW1. The engine coolant temperature TW immediately after the F / C request flag is set is set as the starting coolant temperature TW1.In the present embodiment, the fuel cut is temporarily interrupted when there is a warm-up request, and the lowering amount of the engine coolant temperature TW from a start of fuel cut is greater than or equal to the interruption determination value T1.

[0046] In the present embodiment, such a controller for an engine performs an interruption process that interrupts the fuel cut when the following two conditions are met during the fuel cut for filter regeneration. Condition (A): Heating of the vehicle interior is requested, and Condition (B): The engine coolant temperature TW becomes lower than or equal to a predetermined temperature after the start of the fuel cut, specifically, a value obtained by subtracting the interruption determination value T1 from the starting coolant temperature TW1.

[0047] In the present embodiment, the operation map MAP1 stored in advance in the memory 42 of the electronic control unit 40 is used to set the interruption determination value T1 based on the engine coolant temperature TW, as described above. Fig. 4 shows the relationship between the engine coolant temperature TW and the cut-off determination value T1 in the operation map MAP1. In a case where the engine coolant temperature TW is higher than a certain level, even if the engine coolant temperature TW subsequently drops slightly, the temperature of the air sent to the vehicle interior is not sufficiently lowered to a level that is noticeable by the vehicle occupants. When the engine coolant temperature TW drops to less than or equal to the air supply stop temperature TW0, the air flow sent to the vehicle interior is stopped, so that the vehicle occupants do not notice the change. Accordingly, the cut-off determination value T1 in the present embodiment, as shown in Fig. 4, is set to a larger value when the engine coolant temperature TW is high than when the engine coolant temperature TW is low. That is, the cutoff determination value T1 is set to monotonically increase as the engine coolant temperature TW increases. In the present embodiment, 0 is set as the cutoff determination value T1 in a low temperature range including the air supply stop temperature TW0, so that the fuel cut is interrupted before the engine coolant temperature TW is reduced to the air supply stop temperature TW0.

[0048] When the fuel cut is interrupted, combustion in the engine 10 is restarted to cause the engine coolant temperature TW to rise. In the present embodiment, when the post-interruption coolant temperature rise amount becomes higher than or equal to the restart determination value T2 after the fuel cut is interrupted (S240: YES), the interruption flag is cleared (S250), and the fuel cut is re-permitted (S260). The post-interruption coolant temperature rise amount is the difference obtained by subtracting the interruption coolant temperature TW2 from the current engine coolant temperature TW. When the fuel cut is interrupted, the engine coolant temperature TW is set as the interruption coolant temperature TW2.In the present embodiment, the fuel cut is restarted when the increase amount of the engine coolant temperature TW after the fuel cut is interrupted becomes greater than or equal to the restart determination value T2.

[0049] In the present embodiment, such a controller for an engine performs a restart operation that restarts the fuel cut after the fuel cut is canceled in the interruption operation when the following condition is met. Condition (C): The engine coolant temperature TW becomes higher than or equal to a predetermined temperature after a fuel cut is interrupted, specifically, a value obtained by adding the restart determination value T2 to the interruption coolant temperature TW2.

[0050] In the present embodiment, the operation map MAP2 stored in advance in the memory 42 of the electronic control unit 40 is used to set the restart determination value T2 based on the engine coolant temperature TW when the fuel cut is interrupted as described above. Fig. 5 shows the relationship between the engine coolant temperature TW and the restart determination value T2 in the operation map MAP2. As described above, during warming up of the vehicle interior, the fuel cut can be interrupted before the air flow to the vehicle interior is stopped when the engine coolant temperature TW becomes lower than or equal to the air supply stopping temperature TW0. Thus, in the present embodiment, the restart determination value T2 is set to a larger value when the engine coolant temperature TW is low than when the engine coolant temperature TW is high, in order to restart the fuel cut when the engine coolant temperature TW is slightly higher than the air supply stopping temperature TW0. That is, the restart determination value T2 is set to monotonically decrease as the engine coolant temperature TW rises.

[0051] When the fuel cut is restarted, the current engine coolant temperature TW is again set as the starting coolant temperature TW1. Thus, after the fuel cut is restarted, the fuel cut is interrupted again if the decrease in the engine coolant temperature TW after the restart becomes greater than or equal to the interruption determination value T1 before the filter regeneration is completed.

[0052] Fig. 6 shows an example of filter regeneration control when a heating request is issued during air conditioning control in the present embodiment. Fig. 6, dashed lines show a change in the engine coolant temperature TW when the fuel cut for filter regeneration is continued until the regeneration of the filter 28 is completed, even if the engine coolant temperature TW decreases while heating is requested.

[0053] At a time t1 in Fig. 6, a temperature rise operation causes the estimated filter temperature TF to rise higher than or equal to the PM combustion temperature and sets the F / C request flag. Fuel cut is started at time t1. During fuel cut, no combustion is performed in engine 10, and the engine coolant temperature TW drops. Accordingly, if fuel cut continues until regeneration of filter 28 is completed, the engine coolant temperature TW becomes excessively low, and the vehicle interior may not be sufficiently warmed.

[0054] In this regard, in the present embodiment, the interrupt flag is set to interrupt the fuel cut when the decrease amount of the engine coolant temperature TW after the fuel cut reaches the interrupt determination value T1 at time t2. As a result, combustion in the engine 10 is restarted to cause the engine coolant temperature TW to rise from time t2.

[0055] Then, when the increase in engine coolant temperature TW after the fuel cutoff is suspended reaches the restart determination value T2 at time t3, the suspension flag is cleared and the fuel cutoff is restarted. Then, filter regeneration is completed, the F / C request flag is cleared at time t4, and the fuel cutoff ends at time t4.

[0056] The engine controller of the present embodiment maintains heating performance even when filter regeneration is performed when the vehicle interior is warmed up. That is, the engine controller performs fuel cutoff for filter regeneration without adversely affecting drivability, which may result from reduced heating performance when the vehicle interior is warmed up. As a result, fuel cutoff does not need to be inhibited to maintain heating performance. This increases the possibility of performing filter regeneration through fuel cutoff.

[0057] The present embodiment may be modified as described below. The present embodiment and the following modifications may be combined as long as the combined modifications do not contradict each other.

[0058] In the embodiment, the interruption determination value T1 and the restart determination value T2 are set variably based on the engine coolant temperature TW. Instead, these values ​​may be fixed.

[0059] In the embodiment, the restart of a fuel cut after the interruption is determined based on the amount of increase in the engine coolant temperature TW after the interruption. This determination can be made based on the value of the engine coolant temperature TW. That is, a fuel cut can be restarted when the engine coolant temperature TW becomes higher than or equal to a fixed value after the fuel cut is interrupted.

[0060] Furthermore, the timing for restarting a fuel cutoff may be determined based on a parameter other than the engine coolant temperature TW. For example, the fuel cutoff may be restarted when a fixed period of time has elapsed since the fuel cutoff was interrupted.

[0061] In the embodiment, the restart of a fuel cut when heating is requested is determined based on the decrease in the engine coolant temperature TW after the fuel cut is started. This determination can be made based on the value of the engine coolant temperature TW. That is, a fuel cut can be interrupted when the engine coolant temperature TW becomes lower than or equal to a fixed value after the fuel cut is started.

[0062] In the present embodiment, the controller performs fuel cutoff or filter regeneration for an engine 10 while maintaining rotation of the engine 10 with power generated by the first motor generator 11. Alternatively, such fuel cutoff may be performed while maintaining rotation of the engine 10 with power transmitted from a wheel during idling of a vehicle.

[0063] Filter regeneration control by the controller for an engine in the present embodiment may be applied to vehicles other than hybrid vehicles in the same or similar manner.

[0064] The electronic control unit 40, which corresponds to the controller for a machine, includes an arithmetic processing circuit 41 and a memory 42, and executes software processing. However, this is merely an example. For example, the electronic control unit 40 may include a dedicated hardware circuit (such as an ASIC) that executes at least part of the software processing performed in the above embodiment. That is, the electronic control unit 40 may be modified to have any of the following configurations (a) to (c). (a) A configuration including a processor that executes all the above-described operations according to programs, and a program storage device, such as a memory, that stores the programs.(b) A device including a processor that performs some of the above-described operations according to the programs, and a program storage device and a dedicated hardware circuit that performs the remaining operations. (c) A device including a dedicated hardware circuit that performs all of the above-described operations. A plurality of software circuits, each including a processor and a program storage device, and a plurality of dedicated hardware circuits may be provided. That is, the above-mentioned operations may be performed by a processing circuit including at least one of a series of one or more software circuits or a series of one or more dedicated hardware circuits. The program storage device or computer-readable media includes any type of media accessible by general-purpose computers and dedicated computers.

[0065] Various changes in form and detail may be made to the above examples without departing from the spirit and scope of the claims and their equivalents. These examples are for the purpose of description only and not of limitation. Descriptions of features in each example are intended to be applicable to similar features or aspects in other examples. Suitable results may be obtained if sequences are performed in a different order, and / or if components in a described system, architecture, device, or circuit are combined differently, and / or are replaced or supplemented with other components or their equivalents. The scope of the invention is not defined by the detailed description, but by the claims and their equivalents. All variations within the scope of the claims and their equivalents are included within the invention.

Claims

[1] A controller for an engine, the engine being installed in a vehicle, configured to use heat from an engine coolant to heat a vehicle interior, and the engine including an exhaust duct including a filter configured to collect particulate matter from exhaust gas, the controller comprising: a processing circuit configured to perform a fuel cut-off for regenerating the filter by burning the particulate matter collected in the filter, and wherein the processing circuit is configured to perform an interruption process for interrupting the fuel cut in a case where heating of the vehicle interior is requested when the fuel cut is performed and an engine coolant temperature, which is a temperature of the engine coolant, becomes lower than or equal to a predetermined temperature after the fuel cut is started. [2] The controller for an engine according to claim 1, wherein the processing circuit is configured to interrupt the fuel cut in the interrupting process in a case where an amount of lowering of the engine coolant temperature with the start of the fuel cut becomes greater than or equal to an interruption determination value. [3] The controller for an engine according to claim 2, wherein the interruption determination value is set to a larger value when the engine coolant temperature is high than when the engine coolant temperature is low. [4] A controller for an engine according to any one of claims 1 to 3, wherein the processing circuit is configured to perform a restart operation that restarts the fuel cut when the engine coolant temperature becomes higher than or equal to a predetermined temperature after the fuel cut is interrupted by the interrupt operation. [5] The controller for an engine according to claim 4, wherein the processing circuit is configured to restart the fuel cut in the restarting operation when an amount of increase in the engine coolant temperature after the fuel cut is interrupted by the interrupting operation becomes greater than or equal to a restart determination value. [6] The controller for an engine according to claim 5, wherein the restart determination value is set to a larger value when the engine coolant temperature is low than when the engine coolant temperature is high. [7] A method of controlling an engine, the engine being installed in a vehicle configured to use heat from an engine coolant to heat a vehicle interior, and the engine including an exhaust duct including a filter configured to collect particulate matter from exhaust gas, the method comprising: Performing a fuel cut-off to regenerate the filter by burning the particulate matter collected in the filter; and Performing an interruption process that interrupts the fuel cut in a case where heating of the vehicle interior is requested when the fuel cut is performed and an engine coolant temperature, which is a temperature of the engine coolant, becomes lower than or equal to a predetermined temperature after the fuel cut is started.

Images