Hybrid vehicle control device

Abstract

To provide a control device for a hybrid vehicle capable of improving fuel economy of an engine by accurately estimating a fuel dilution amount of engine oil in the engine intermittently operated or intermittently stopped.SOLUTION: A control device for a hybrid vehicle intermittently operates or stops an engine, calculates a dilution amount of fuel mixed into engine oil of the engine and diluting the engine oil, and starts the engine when the dilution amount exceeds a prescribed amount predetermined as a threshold value during stopping of the engine. A first evaporation amount is calculated or estimated as an amount of the fuel evaporated from the engine oil during operation of the engine, the dilution amount is subtracted in accordance with the first evaporation amount, a second evaporation amount is calculated or estimated as an amount of the fuel evaporated from the engine oil during stopping of the engine, and the dilution amount is further subtracted in accordance with the second evaporation amount (step S5).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle equipped with an engine (internal combustion engine) and a motor as driving power sources.

Background Art

[0002] Patent Document 1 describes an invention related to a control device for a hybrid vehicle aimed at suppressing the mixing of condensed water into engine oil. The control device for the hybrid vehicle described in this Patent Document 1 includes an internal combustion engine (engine) and a motor as driving power sources for traveling, and controls a hybrid vehicle that travels while intermittently operating (or intermittently stopping) the engine. The control device calculates the amount of dilution water that mixes into the engine oil and dilutes the engine oil, and is configured to operate the engine when the calculated amount of dilution water exceeds a predetermined threshold value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described in the above Patent Document 1, an engine (internal combustion engine) mounted on a hybrid vehicle is used in combination with a motor as a driving force source, and its operating and stopping states are repeatedly alternated intermittently. When EV driving, in which the engine is stopped and the vehicle runs by the output of the motor, is frequently used, it becomes difficult to warm up the engine, and the frequency of cold starting the engine increases. When the engine is cold-started, the moisture contained in the blow-by gas of the engine is likely to be liquefied, and the liquefied moisture (condensed water) is likely to mix into the engine oil. On the other hand, as the engine warms up and the temperature of the engine oil rises, the condensed water mixed into the engine oil evaporates, and the amount of dilution moisture is likely to decrease. In contrast, in the control device of the hybrid vehicle described in the above Patent Document 1, when the amount of dilution moisture in the engine oil exceeds a predetermined threshold value, the engine is forcibly operated. By operating the engine, the warm-up of the engine is promoted, and the temperature of the engine oil rises early. Therefore, the condensed water mixed into the engine oil is likely to evaporate, and as a result, an increase in the condensed water in the engine oil can be suppressed. That is, it is possible to suppress the engine oil from being diluted by the condensed water, the performance of the engine oil from deteriorating, or the engine oil from deteriorating.

[0005] The phenomenon of engine oil dilution as described above can also occur due to the engine fuel. That is, for example, when fuel injection or fuel in unburned gas flows into the engine cylinder, it mixes into the engine oil, resulting in the dilution of the engine oil. The fuel mixed into the engine oil evaporates when the temperature of the engine oil rises during engine operation. Therefore, in the engine of a hybrid vehicle where the operation and stop states are intermittently repeated as described above, compared with the engine of a conventional engine vehicle, the frequency of cold start is higher, and the period of operation in a cold state (before warm-up is completed) becomes longer. As a result, the fuel mixed into the engine oil is less likely to evaporate. Therefore, the amount of fuel mixed into the engine oil (fuel dilution amount) increases, and the engine oil is more likely to be diluted by the mixed fuel. On the other hand, considering the diluted moisture content of the engine oil in the control device of the hybrid vehicle described in Patent Document 1 above, similar to the control of operating the engine, when the fuel dilution amount (estimated value) of the engine oil exceeds a predetermined value, the engine is operated to evaporate the fuel mixed into the engine oil, thereby suppressing the increase in the fuel dilution amount of the engine oil and suppressing the deterioration of the engine oil.

[0006] However, if the estimation error of the fuel dilution amount of the engine oil is large, the frequency of forcibly starting the engine to evaporate the fuel mixed in the engine oil will increase more than necessary. As a result, the fuel consumption of the engine may deteriorate. For example, in the above hybrid vehicle, even when the engine operation is intermittently stopped, evaporation of the fuel mixed in the engine oil occurs. In the intermittent operation (intermittent driving) and stop (intermittent stop) of the engine in a hybrid vehicle, when starting the intermittent stop, that is, immediately after stopping the intermittent driving, the temperature of the engine oil is still high, and even during the stop of the engine operation, fuel evaporates from the engine oil. If the fuel dilution amount of the engine oil is estimated without considering the evaporation of the fuel during such an intermittent stop of the engine, the error of estimating the fuel dilution amount to be larger than the actual value will increase. As a result, the engine will be forcibly operated even when it is not actually necessary, and the fuel consumption of the engine will deteriorate. Consequently, there is a risk of causing a decrease in the energy efficiency of the hybrid vehicle.

[0007] This invention was conceived by paying attention to the above technical problems, and accurately estimates the fuel dilution amount of the engine oil in an engine that intermittently operates or stops, and appropriately operates the engine based on the estimation, so as to provide a control device for a hybrid vehicle capable of improving the fuel consumption of the engine.

Means for Solving the Problems

[0008] To achieve the above object, this invention is a control device for a hybrid vehicle that includes an engine and a motor as power sources, intermittently operates or stops the engine, obtains a dilution amount that is the amount of fuel of the engine that mixes into the engine oil of the engine and dilutes the engine oil, and forcibly starts the engine when the dilution amount exceeds a predetermined amount defined as a threshold value during the stop of the engine. The control device includes a controller for controlling the engine, and the controller calculates or estimates the dilution amount, and the engine The vehicle that is rotating by burning the fuel before Calculate or estimate a first evaporation amount as the amount of the fuel that evaporates from the engine oil during engine operation, subtract the dilution amount according to the first evaporation amount, and The combustion of the fuel and the engine that has stopped the rotation calculate or estimate a second evaporation amount as the amount of the fuel that evaporates from the engine oil while the engine is stopped, and further subtract the dilution amount according to the second evaporation amount.

[0009] In addition, the controller in this invention is configured to calculate or estimate the first evaporation amount based on at least the dilution amount, the temperature of the engine oil, and the operation time of the engine, and calculate or estimate the second evaporation amount based on at least the dilution amount, the temperature of the engine oil, and the stop time of the engine.

Advantages of the Invention

[0010] This invention targets a hybrid vehicle equipped with an engine and at least one motor as power sources for control. For example, it may be a parallel hybrid vehicle, a series-parallel hybrid vehicle (or split hybrid vehicle), or a series hybrid vehicle (or an electric vehicle equipped with a so-called range extender). In short, this invention targets a vehicle equipped with an engine that is used in combination with a motor and whose operation (intermittent operation) or stop (intermittent stop) states are repeated intermittently. Such an engine whose intermittent operation or stop is repeated is more likely to have fuel mixed into the engine oil compared to, for example, the engine of a conventional engine vehicle. Therefore, the control device of the hybrid vehicle of this invention obtains the amount of fuel (dilution amount) that mixes into the engine oil and dilutes the engine oil, and when the dilution amount exceeds a predetermined amount defined as a threshold value during the intermittent stop of the engine (that is, when the dilution amount becomes more than the predetermined amount), forcibly starts the engine during the intermittent stop. By starting the engine and raising the temperature of the engine oil, the fuel mixed into the engine oil can be evaporated and the dilution amount can be reduced.

[0011] While forcibly starting the engine as described above to reduce the dilution amount in the engine oil, if the accuracy of calculating or estimating the dilution amount is low, the engine will be started more than necessary, and accordingly, the fuel consumption of the engine will deteriorate. Therefore, in order to accurately obtain the dilution amount in the engine oil as described above, the control device for a hybrid vehicle according to the present invention obtains the evaporation amount of fuel evaporated from the engine oil during engine operation and during intermittent engine stoppage, and calculates or estimates the dilution amount in the engine oil by reflecting the evaporation amount. Specifically, the amount of fuel evaporated from the engine oil during engine operation (first evaporation amount) is calculated or estimated, and the first evaporation amount is subtracted from the dilution amount in the engine oil. Further, in the control device for a hybrid vehicle according to the present invention, the amount of fuel evaporated from the engine oil during intermittent engine stoppage (second evaporation amount) is calculated or estimated, and the second evaporation amount is subtracted from the dilution amount in the engine oil. Therefore, in addition to the first evaporation amount of fuel evaporated during engine operation, the second evaporation amount of fuel evaporated during intermittent engine stoppage is also reflected, and the dilution amount in the engine oil can be accurately obtained.

[0012] Note that the first evaporation amount as described above is accurately calculated or estimated, for example, based on at least the dilution amount in the engine oil, the temperature of the engine oil, and the operation time of the engine. Similarly, the second evaporation amount is accurately calculated or estimated, for example, based on at least the dilution amount in the engine oil, the temperature of the engine oil, and the engine stoppage time during intermittent stoppage.

[0013] Therefore, according to the control device for a hybrid vehicle of the present invention, the dilution amount (the amount of fuel mixed in) in the engine oil in an engine that operates intermittently or stops intermittently can be accurately calculated or estimated, and based on the accurately calculated or estimated dilution amount, the engine can be appropriately operated. Therefore, the frequency of forced engine starts as described above can be suppressed to the minimum necessary, thereby improving the fuel consumption of the engine or enhancing the fuel efficiency of the engine. As a result, the energy efficiency of the hybrid vehicle controlled in the present invention can be improved.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

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Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely examples when the present invention is embodied, and do not limit the present invention.

[0016] In an embodiment of the present invention, a hybrid vehicle equipped with an engine (internal combustion engine) and at least one motor as power sources is the control target. For example, a well-known parallel hybrid vehicle may be used. Alternatively, a series-parallel (or split) hybrid vehicle may be used. For example, a split hybrid vehicle having a power split mechanism and a reduction mechanism as shown in "FIG. 1" of Patent Document 1 described above may be used. Alternatively, a series hybrid vehicle (or an electric vehicle equipped with a so-called range extender) may be used. In short, in an embodiment of the present invention, a vehicle equipped with an engine that is used in combination with a motor and whose operation (intermittent operation) and stop (intermittent stop) states are repeated intermittently is the control target. FIG. 1 shows an example of a configuration to be controlled in an embodiment of the present invention.

[0017] The vehicle Ve shown in FIG. 1 is a hybrid vehicle and includes an engine (ENG) 1, a first motor (MG1) 2, and a second motor (MG2) 3 as power sources (driving power sources). FIG. 1 reproduces the configuration of a so-called split hybrid vehicle shown in "FIG. 1" of Patent Document 1 described above. The vehicle Ve includes a power split mechanism 4, a reduction mechanism 5, a detection unit 6, and a controller (ECU) 7 as main components together with the above driving power sources.

[0018] The engine 1 is an internal combustion engine that obtains power (mechanical energy) by burning fuel, such as a gasoline engine or a diesel engine, and is configured to electrically control the adjustment of the output and the operating states such as starting and stopping. In the case of a gasoline engine, the opening degree of the throttle valve, the supply amount or injection amount of fuel, the execution and stop of ignition, and the ignition timing are electrically controlled. Also, in the case of a diesel engine, the injection amount of fuel, the injection timing of fuel, or the opening degree of the throttle valve (in the EGR system) is electrically controlled.

[0019] The first motor 2 also has a function as a generator that generates electric power by being driven by receiving the torque output by the engine 1. That is, the first motor 2 is a motor having a power generation function (so-called motor - generator), and is configured by, for example, a permanent magnet type synchronous motor or an induction motor. A battery (not shown) is connected to the first motor 2 via an inverter (not shown). Therefore, the first motor 2 can be made to function as a generator, and the electric power generated at that time can be stored in the battery. Also, the electric power stored in the battery can be supplied to the first motor 2, and the first motor 2 can be made to function as a prime mover to output driving torque.

[0020] The second motor 3 is connected so as to be able to transmit power to the drive wheels 8 (for example, the front wheels of the vehicle Ve) via a speed reduction mechanism 5 described later, for example. The second motor 3 also has a function as a generator that generates electric power by being driven while receiving torque from the outside. That is, the second motor 3 is a motor having a power generation function (so-called motor - generator), similar to the first motor 2 described above, and is constituted by, for example, a permanent magnet type synchronous motor, or an induction motor, etc. A battery (not shown) is connected to the second motor 3 via an inverter (not shown). Therefore, it is possible to supply the electric power stored in the battery to the second motor 3, make the second motor 3 function as a prime mover, and output drive torque. Also, it is possible to make the second motor 3 function as a generator by the torque transmitted from the drive wheels 8 and store the regenerative electric power generated at that time in the battery. Furthermore, the first motor 2 and the second motor 3 are connected via an inverter so as to be able to exchange electric power with each other. Therefore, for example, it is also possible to directly supply the electric power generated by the first motor 2 to the second motor 3 and output drive torque by the second motor 3.

[0021] The power split mechanism 4 is a well - known power transmission device for a hybrid vehicle and is constituted by a "planetary gear mechanism" having at least three rotating elements: an input element, an output element, and a reaction force element. Specifically, the power split mechanism 4 is constituted by a "single pinion type planetary gear mechanism" having a sun gear 4a, a ring gear 4b, and a carrier 4c. The sun gear 4a is connected to the rotation shaft 2a of the first motor 2 as a reaction force element. The ring gear 4b has an output gear 9 of an external gear formed on its outer peripheral portion as an output element. And the carrier 4c is connected to the output shaft 1a of the engine 1 via a damper mechanism 10 as an input element.

[0022] The speed reduction mechanism 5 is constituted by a "single pinion type planetary gear mechanism" having a sun gear 5a, a ring gear 5b, and a carrier 5c. The sun gear 5a is connected to the rotating shaft 3a of the second motor 3. The ring gear 5b is integrally formed with the ring gear 4b of the power split mechanism 4, and an output gear 9 of an external gear is formed on the outer peripheral portion together with the ring gear 4b of the power split mechanism 4. The carrier 5c is fixed to a case (not shown) or the like so as not to rotate. And the speed reduction mechanism 5 is configured such that the rotational speed of the ring gear 5b, that is, the output gear 9, is reduced with respect to the rotational speed of the sun gear 5a, that is, the rotating shaft 3a of the second motor 3. Therefore, the speed reduction mechanism 5 amplifies the output torque of the second motor 3 and transmits it to the output gear 9. The output gear 9 is connected to the drive wheels 8 via a reduction gear 11, a differential gear 12, and a drive shaft 13.

[0023] The detection unit 6 is a device or apparatus for acquiring various data and information necessary when controlling the vehicle Ve. For example, it includes a power supply unit, a microcomputer, sensors, an input / output interface, and the like. In particular, the detection unit 6 in the embodiment of this invention detects various data for controlling the engine 1 that operates intermittently or stops intermittently. For example, the detection unit 6 has various sensors and devices such as an engine speed sensor 6a that detects the rotational speed of the engine 1, an engine torque sensor 6b that detects the output torque of the engine 1, an oil temperature sensor 6c that detects the temperature of engine oil (not shown), and a timer 6d that detects the operating state of the engine 1, the elapsed time or the continuous time of control, and the like. And the detection unit 6 is electrically connected to a controller 7 described later, and outputs an electrical signal corresponding to the detection values or calculated values of the various sensors, devices, and apparatuses as described above to the controller 7 as detection data.

[0024] The controller 7 is an electronic control device mainly composed of, for example, a microcomputer. The controller 7 in the embodiment of the present invention mainly controls the operation of the engine 1 that operates intermittently or stops intermittently. Various data detected or calculated by the detection unit 6 described above are input to the controller 7. The controller 7 performs calculations using the input various data and pre-stored data, calculation formulas, etc. Then, the controller 7 outputs the calculation result as a control command signal and is configured to control the operation of the engine 1 as described above. In FIG. 1, an example in which one controller 7 is provided is shown, but a plurality of controllers 7 may be provided for each device or equipment to be controlled or for each control content.

[0025] The engine 1 mounted on the vehicle Ve as described above, that is, the "hybrid vehicle", intermittently operates and stops according to the driving state, the operating states of the motors 2 and 3, etc. That is, it is controlled to operate intermittently and stop intermittently. The engine 1 in which such intermittent operation and intermittent stop are repeated is likely to have an increased amount of fuel mixed into the engine oil compared to a conventional "engine" mounted on a conventional "engine vehicle" as described above. Or, the fuel mixed into the engine oil is likely to accumulate. The fuel mixed into the engine oil evaporates when the temperature of the engine oil rises during the operation of the engine. On the other hand, as described above, the "engine" of the "hybrid vehicle" in which the operation and stop states are repeated intermittently has a higher frequency of cold start and a longer period of operation in the cold state before the warm-up is completed compared to the "engine" of the conventional "engine vehicle", so the fuel mixed into the engine oil is less likely to evaporate. As a result, the fuel mixed into the engine oil increases or accumulates, and the engine oil is likely to be diluted by the fuel. In this way, when the fuel mixed into the engine oil increases and the engine oil is diluted by the fuel, the performance of the engine oil deteriorates, or the engine oil deteriorates.

[0026] Therefore, the control device for a hybrid vehicle according to an embodiment of the present invention obtains the amount of fuel (dilution amount) that mixes into the engine oil and dilutes the engine oil, and when the dilution amount exceeds a predetermined amount set as a threshold value during the intermittent stop of Engine 1, that is, when the dilution amount becomes larger than the predetermined amount, Engine 1 during the intermittent stop is forcibly started. By operating Engine 1 to raise the temperature of the engine oil, the fuel mixed into the engine oil can be evaporated, and the dilution amount can be reduced.

[0027] However, if the calculation accuracy or estimation accuracy of the dilution amount, which is the determination material when starting Engine 1, is low, there is a possibility that Engine 1 will be forcibly started even in a state where it is not actually necessary to start Engine 1. As a result, the fuel consumption of Engine 1 deteriorates. Therefore, in the control device for a hybrid vehicle according to an embodiment of the present invention, in order to accurately obtain the dilution amount in the engine oil as described above, in addition to during the operation of Engine 1, the evaporation amount of the fuel that evaporates from the engine oil during the intermittent stop is obtained, and the dilution amount in the engine oil is calculated or estimated while reflecting the evaporation amount. A specific example of such control is shown in the flowchart of FIG. 2.

[0028] In the flowchart of FIG. 2, first, in step S1, it is determined whether Engine 1 has been started. If it is determined negatively in this step S1 because Engine 1 has not been started yet, the routine shown in this flowchart of FIG. 2 is terminated once without executing the subsequent control.

[0029] On the other hand, if it is determined affirmatively in step S1 because Engine 1 has been started, the process proceeds to step S2.

[0030] In step S2, the previous dilution amount is read. Specifically, the dilution amount in the engine oil calculated (estimated) in the previous routine, that is, the amount of fuel estimated to mix into the engine oil and dilute the engine oil, is read. In the first routine, "0" is read as the dilution amount.

[0031] Subsequently, in step S3, it is determined whether the engine 1 is in continuous operation. The continuous operation state of the engine 1 is not an intermittent stop state, but a state in which the engine 1 is operating. If, after determining that the engine 1 was started in step S1 above, the engine 1 has not yet stopped, it is determined that the engine 1 is in continuous operation. If it is affirmatively determined in this step S3 that the engine 1 is in continuous operation, the process proceeds to step S4.

[0032] In step S4, the evaporation amount (first evaporation amount) of the fuel evaporated from the engine oil during the continuous operation of the engine 1 is calculated. Specifically, the first evaporation amount is estimated based on the dilution amount read in step S2 above, the temperature of the engine oil, and the operation time (duration of the operation state) of the engine 1. For example, it is estimated that the first evaporation amount is larger when the temperature of the engine oil during continuous operation is relatively high than when the temperature of the engine oil is relatively low under a certain dilution amount. Also, it is estimated that the longer the operation time of the engine 1 during continuous operation, the larger the first evaporation amount. Note that in the first routine, since the dilution amount is "0" as described above, the first evaporation amount is also calculated as "0".

[0033] Subsequently, in step S5, a subtraction process is performed on the previous dilution amount. Specifically, the first evaporation amount estimated in step S4 above is subtracted from the dilution amount read in step S2 above. That is, considering the fuel component (first evaporation amount) evaporated during the operation of the engine 1, the dilution amount in the engine oil is updated. Therefore, the dilution amount used as a determination material when forcibly starting the engine 1 can be accurately obtained by appropriately reflecting the first evaporation amount. Note that in the first routine or when the second evaporation amount described later has not yet been calculated, only the first evaporation amount as described above is reflected, and the dilution amount in the engine oil is updated. As will be described later, when the second evaporation amount is calculated, together with the first evaporation amount described above, the second evaporation amount is also subtracted from the dilution amount in the engine oil.

[0034] In this step S5, in consideration of the first evaporation amount that evaporates during the operation of the engine 1, subtraction processing is performed on the dilution amount in the engine oil, and when the dilution amount is updated, the routine shown in the flowchart of FIG. 2 is temporarily terminated.

[0035] On the other hand, when it is determined negatively in the aforementioned step S3 because the engine 1 is not in continuous operation, that is, the engine 1 is in intermittent stop, the process proceeds to step S6.

[0036] In step S6, the evaporation amount (second evaporation amount) of the fuel that evaporates from the engine oil during the intermittent stop of the engine 1 is calculated. Specifically, the second evaporation amount is estimated based on the dilution amount read in step S2 above, the temperature of the engine oil, and the stop time of the engine 1 (duration of the intermittent stop state). For example, it is estimated that the second evaporation amount is larger when the temperature of the engine oil during intermittent stop is relatively high than when the temperature of the engine oil is relatively low under a certain dilution amount. Also, it is estimated that the longer the stop time of the engine 1 during intermittent stop, the larger the second evaporation amount.

[0037] When the second evaporation amount is calculated in this step S6, the second evaporation amount is stored and added to the subtraction amount in the subtraction processing for the dilution amount in step S5 described above. Then, the process returns to step S3 described above, and the control after step S3 is executed in the same manner as before. That is, when the engine 1 is intermittently stopped and the second evaporation amount is calculated in this step S6, in step S5, the second evaporation amount is subtracted from the dilution amount in the engine oil together with the first evaporation amount.

[0038] Note that the control shown in step S6 in the flowchart of FIG. 2 above may be executed as shown in step S6 in the flowchart of FIG. 3. That is, after the second evaporation amount is calculated in step S6, the process proceeds to the aforementioned step S5. Then, in step S5, the second evaporation amount is subtracted together with the first evaporation amount. Even when the subtraction process for the dilution amount is performed in this way, the dilution amount in the engine oil can be accurately estimated in the same manner as in the example shown in the flowchart of FIG. 2 above.

[0039] In the conventional control, for example, as shown in FIG. 4(a), the amount of fuel evaporated from the engine oil during the intermittent stop of the engine 1, that is, the second evaporation amount, is not considered. Therefore, as shown in FIG. 4(b), the difference between the actual amount of fuel evaporated from the engine oil and the estimated amount of fuel evaporation has become large. On the other hand, in the control device of the hybrid vehicle according to the embodiment of the present invention, as shown in FIG. 5(a), during the operation of the engine 1, the fuel evaporated from the engine oil during the intermittent stop of the engine 1 is taken into account, and the evaporation amount of the fuel is estimated. That is, the second evaporation amount as described above is considered, and the evaporation amount of the fuel is estimated. Therefore, as shown in FIG. 5(b), the difference between the actual amount of fuel evaporated from the engine oil and the estimated amount of fuel evaporation has become small. That is, the evaporation amount of the fuel for obtaining the dilution amount in the engine oil is accurately estimated.

[0040] Therefore, according to the control device of the hybrid vehicle according to the embodiment of the present invention, the dilution amount (the amount of fuel mixed into the engine oil) in the engine oil in the engine 1 that operates intermittently or stops intermittently can be accurately calculated or estimated. And based on such accurately calculated or estimated dilution amount, the engine 1 can be appropriately operated. Therefore, the frequency of the above-mentioned forced start of the engine 1 can be suppressed to the minimum necessary, thereby improving the fuel consumption of the engine 1 or improving the fuel consumption of the engine 1. As a result, the energy efficiency of the vehicle Ve to be controlled in the embodiment of the present invention can be improved.

Description of Symbols

[0041] 1 Engine (ENG) 1a Output shaft of the engine 2 First motor (MG1) 2a Rotation shaft of the first motor 3 Second motor (MG2) 3a Rotation shaft of the second motor 4 Power split mechanism 4a Sun gear of the power split mechanism 4b Ring gear of the power split mechanism 4c Carrier of the power split mechanism 5 Reduction mechanism 5a Sun gear of the reduction mechanism 5b Ring gear of the reduction mechanism 5c Carrier of the reduction mechanism 6 Detection unit 6a Engine speed sensor of the detection unit 6b Engine torque sensor of the detection unit 6c Oil temperature sensor of the detection unit 6d Timer of the detection unit 7 Controller (ECU) 8 Driving wheels 9 Output gear 10 Damper mechanism 11 Reduction gear 12 Differential gear 13 Drive shaft Ve Vehicle (Hybrid vehicle)

Claims

【Claim 1】 A control device for a hybrid vehicle, comprising an engine and a motor as power sources, intermittently operating and stopping the engine, obtaining a dilution amount which is the amount of fuel of the engine that mixes into the engine oil and dilutes the engine oil, and starting the engine when the dilution amount exceeds a predetermined amount defined as a threshold value during the stop of the engine, comprising a controller for controlling the engine, wherein the controller, calculates or estimates the dilution amount, calculates or estimates a first evaporation amount which is the amount of fuel evaporated from the engine oil during operation in which the engine rotates by burning the fuel, subtracts the dilution amount according to the first evaporation amount, and calculates or estimates a second evaporation amount which is the amount of fuel evaporated from the engine oil during the stop of the engine in which the fuel combustion and the rotation are stopped, and further subtracts the dilution amount according to the second evaporation amount A control device for a hybrid vehicle, characterized in that.

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