Control apparatus for hybrid vehicle

Abstract

To provide a control apparatus for a hybrid vehicle that can extend an available travel distance of evacuation travel in a case where an output abnormality of an engine occurs.SOLUTION: In a case where an abnormality occurs in an effective engine output Pe and when an average value Pav of the effective engine output Pe during a given period TS is less than a predetermined threshold TH greater than zero, the engine 12 is stopped and evacuation travel is performed only with power from a second motor MG2. When the average value Pav is equal to or higher than the threshold TH, evacuation travel is performed with power from the engine 12 and the second motor MG2. Thus, in a case where an output abnormality of the engine 12 occurs and the average value Pav is equal to of higher than the threshold TH, the engine 12 is driven instead of being stopped, reducing power consumption (reduction in charged power) of a battery 54 by the second motor MG2, thus making it possible to extend the available travel distance of evacuation travel.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle, and to a technique for performing evacuation driving when an abnormality occurs in the engine. [Background technology]

[0002] In hybrid vehicles powered by an engine and an electric motor, a technology is known that stops the engine and performs evacuation driving using the electric motor's power when an abnormality occurs in the engine output. However, during evacuation driving, the charge level of the battery that powers the electric motor decreases, and if the charge level falls below a predetermined level, the vehicle becomes unable to drive, limiting the distance that can be traveled during evacuation driving. Therefore, it is desirable to suppress the transition to evacuation driving as much as possible. To this end, a technology has been disclosed that, when the cause of the abnormality in the engine output is an output abnormality due to an incorrect retardation of the engine ignition timing, changes the operating point to an operating range where an output abnormality due to an incorrect retard does not occur without detecting the abnormality, thereby allowing the engine to continue driving. For example, a hybrid vehicle described in Patent Document 1 is such a technology. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-20588 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the technology described in Patent Document 1 is effective for output abnormalities caused by the aforementioned erroneous retardation of the engine ignition timing, but is ineffective for output abnormalities caused by other factors. If the engine is stopped when an abnormality caused by other factors is detected, the vehicle will then switch to evacuation driving using the electric motor, resulting in a limited mileage. Even in cases where an engine output abnormality is detected, for example, if engine output is possible, running the engine rather than stopping it reduces the battery's power consumption (reduction in charge level) by the electric motor and can extend the mileage. In other words, there is room for improvement in the mileage during evacuation driving.

[0005] The present invention was made against the background of the above circumstances, and its purpose is to provide a control device for a hybrid vehicle that can extend the distance that can be traveled during evacuation driving in the event of an engine output abnormality. [Means for solving the problem]

[0006] The gist of the first invention is (a) a control device for a hybrid vehicle powered by an engine and an electric motor, (b) which, if an abnormality occurs in the engine output, performs evacuation running using at least the power of the electric motor, and (c) if an abnormality occurs in the engine output and the average value of the engine output for a specified period is less than a predetermined threshold value that is equal to or greater than 0, stops the engine and performs the evacuation running using the power of the electric motor alone, and if the average value is equal to or greater than the threshold, performs the evacuation running using the power of the engine and the electric motor. [Effects of the Invention]

[0007] According to the first aspect of the present invention, if an abnormality occurs in the engine output and the average value of the engine output for a predetermined period is less than a predetermined threshold value that is equal to or greater than 0, the engine is stopped and the evacuation running is performed using power from the electric motor alone, and if the average value is equal to or greater than the threshold value, the evacuation running is performed using power from the engine and the electric motor. As a result, if an output abnormality occurs in the engine and the average value is equal to or greater than the threshold value, the engine is driven without being stopped, thereby reducing power consumption (decrease in charge level) of the battery by the electric motor and enabling the distance that can be traveled during the evacuation running to be extended. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] 1 is a flowchart illustrating the main control operations of the electronic control device, and is a flowchart illustrating the control operations for evacuation travel when an abnormality occurs in the engine output. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0010] FIG. 1 is a diagram illustrating the schematic configuration of a hybrid vehicle (hereinafter referred to as vehicle) 10 to which the present invention is applied, and also illustrates the main parts of a control system for various controls in the vehicle 10. In FIG. 1, the vehicle 10 is equipped with an engine 12, a first electric motor MG1, and a second electric motor MG2. The vehicle 10 also is equipped with drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14. The vehicle 10 is a hybrid vehicle equipped with the engine 12 and the second electric motor MG2, which function as a power source. The second electric motor MG2 corresponds to the "electric motor" in the present invention.

[0011] The engine 12 is a known internal combustion engine. An engine control device 50 provided in the vehicle 10 is controlled by an electronic control device 90 (described later), whereby the engine torque Te of the engine 12 is controlled.

[0012] The first electric motor MG1 and the second electric motor MG2 are each a rotating electric machine, a so-called motor generator. The first electric motor MG1 and the second electric motor MG2 are each connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The battery 54 is an electricity storage device that supplies and receives electric power to and from each of the first electric motor MG1 and the second electric motor MG2. The inverter 52 is controlled by an electronic control device 90 (described later), thereby controlling the MG1 torque Tg of the first electric motor MG1 and the MG2 torque Tm of the second electric motor MG2.

[0013] The power transmission device 16 includes, within a case 18, a damper 20, an input shaft 22 connected to the crankshaft 12a of the engine 12 via the damper 20, a transmission unit 24 connected to the input shaft 22, a compound gear 26, a driven gear 28, a driven shaft 30, a final gear 32, a differential gear 34, a reduction gear 36, a rotor shaft RSmg1 connected to the rotor of the first electric motor MG1, and a rotor shaft RSmg2 connected to the rotor of the second electric motor MG2. The power transmission device 16 also includes a pair of drive shafts 38 connected to the differential gear 34.

[0014] The compound gear 26 is an output rotation member having a hollow cylindrical shape. A drive gear 26a is integrally provided on one axial end of the outer circumferential surface of the compound gear 26. The drive gear 26a meshes with the driven gear 28 and is connected to the drive wheels 14 so as to be able to transmit power. A parking lock gear 62 for parking lock is integrally provided on the other axial end of the outer circumferential surface of the compound gear 26, separate from the drive gear 26a.

[0015] The driven shaft 30 fixes the driven gear 28 and the final gear 32 so that they cannot rotate relative to each other. The final gear 32 meshes with a differential ring gear 34a of the differential gear 34. The reduction gear 36 meshes with the driven gear 28 and is connected to the rotor shaft RSmg2. The second electric motor MG2 is connected to the drive wheels 14 so as to be able to transmit power, and is also connected to the drive gear 26a so as to be able to transmit power.

[0016] The transmission unit 24 includes a first electric motor MG1 and a planetary gear set 40. The planetary gear set 40 is a differential mechanism and is a known single-pinion planetary gear set including a sun gear S, a carrier CA, a ring gear R, and a plurality of pinions P. The sun gear S is connected to the rotor shaft RSmg1, and is connected to the first electric motor MG1 so as to be able to transmit power. The carrier CA is connected to the input shaft 22 so as to be able to transmit power, and is connected to the engine 12 so as to be able to transmit power. Each pinion P is supported by the carrier CA so as to be able to rotate and revolve. The ring gear R is integrally provided on a part of the inner circumferential surface of the compound gear 26. The ring gear R meshes with the sun gear S via the pinion P. The planetary gear set 40 is a power split mechanism that mechanically splits the power of the engine 12 input to the carrier CA between the first electric motor MG1 and the drive gear 26a. The transmission unit 24 is a known electric continuously variable transmission in which the differential state of the planetary gear device 40 is controlled by controlling the operating state of the first electric motor MG1.

[0017] In the transmission unit 24, in response to the engine torque Te, which is a positive torque, input to the carrier CA, the MG1 torque Tg, which is a reaction torque of the negative torque generated by the first electric motor MG1, is input to the sun gear S. As a result, a positive engine direct torque Td appears in the ring gear R during forward rotation, and the engine direct torque Td is given by the following equation (1). Td=Te / (1+ρ)=-(1 / ρ)×Tg ···(1) The combined torque of the engine direct torque Td and the MG2 torque Tm is transmitted as drive torque to the drive wheels 14. At this time, the electric power generated by the first electric motor MG1 is supplied to the battery 54 and the second electric motor MG2. The above "ρ" is the gear ratio of the planetary gear set 40 (= number of teeth of the sun gear / number of teeth of the ring gear).

[0018] The vehicle 10 is equipped with a shift switching device 58 having a shift lever 56. The shift lever 56 is operated by the driver to one of a plurality of operating positions POSsh. The operating positions POSsh include, for example, a P operating position. The P operating position is a parking operating position for selecting a parking position (= P position) of the transmission unit 24, in which the transmission unit 24 is in a neutral state and rotation of the composite gear 26 is mechanically prevented. The state in which rotation of the composite gear 26 is prevented is a parking lock state (= P lock state) in which the composite gear 26 is mechanically fixed so as to be unable to rotate. When the shift lever 56 is operated to the P operating position, the composite gear 26 (parking lock gear 62) is fixed so as to be unable to rotate by a parking lock mechanism 60 provided in the vehicle 10.

[0019] The vehicle 10 is equipped with an electronic control unit 90 that includes a control device for the vehicle 10. The electronic control unit 90 includes a so-called microcomputer, and performs various controls for the vehicle 10.

[0020] The electronic control device 90 is supplied with various signals (e.g., engine rotation speed Ne, output rotation speed No which is the rotation speed of the driven gear 28 corresponding to the vehicle speed V, MG1 rotation speed Ng, MG2 rotation speed Nm, MG1 current Ig which is the powering or regenerative current value of the first electric motor MG1, operation position POSsh, etc.) based on detection values ​​from various sensors provided on the vehicle 10 (e.g., engine rotation speed sensor 70, output rotation speed sensor 72, MG1 rotation speed sensor 74, MG2 rotation speed sensor 76, MG1 current sensor 78, shift position sensor 80, etc.).

[0021] The electronic control device 90 outputs various command signals (for example, an engine control command signal Se, an MG control command signal Smg, etc.) to each device provided in the vehicle 10 (for example, the engine control device 50, the inverter 52, etc.).

[0022] FIG. 2 is a flowchart illustrating the control operation of the electronic control unit 90 for evacuation travel when an abnormality occurs in the output of the engine 12, and is executed, for example, repeatedly.

[0023] First, in step S10 (hereinafter, step will be omitted), it is determined whether or not an abnormality has occurred in the output of the engine 12. If the determination in S10 is negative, this routine is terminated. The determination in S10 (whether or not an abnormality has occurred) is made based on whether or not the actual engine output (hereinafter referred to as actual engine output) Pe is being output as requested with respect to the requested engine output Pr (=requested engine speed Nr × requested engine torque Tr) commanded by the engine control command signal Se. If the actual engine output Pe is being output as requested, the result is negative, and if it is not being output as requested, the result is positive. The actual engine output Pe is calculated by multiplying the engine speed Ne (a value detected by the engine speed sensor 70) by the actual engine torque (hereinafter referred to as actual engine torque) Ta. The actual engine torque Ta is calculated from the MG1 torque Tg at the same time, for example, by the following equation (2) given from the above-mentioned equation (1): Ta = -(1 + ρ) / ρ × Tg (2) The MG1 torque Tg is calculated from the MG1 rotation speed Ng and the MG1 current Ig, and is applied to a map prepared in advance. The actual engine torque Ta may be detected by a torque detection sensor (torque meter) or the like provided on the crankshaft 12a of the engine 12.

[0024] If the determination in S10 is positive, in S20, an engine control command signal Se is sent to the engine control device 50 to make the required engine output Pr higher than normal. This is performed for the purpose of increasing the average value Pav of the actual engine output Pe, which will be described later, and increasing the possibility of evacuation travel using the engine 12.

[0025] Next, in S30, an average value Pav of the actual engine output Pe for a predetermined period TS is calculated. This is calculated, for example, by calculating the actual engine output Pe (e.g., Pe1 to Pen) corresponding to periodic detection times (e.g., t1 to tn) within the predetermined period TS, and then determining the average value Pav. The predetermined period TS and the detection times (detection period) are set in advance by design or experiment.

[0026] Next, in S40, it is determined whether the average value Pav calculated in S30 is smaller than a predetermined threshold value TH. The threshold value TH is set to, for example, 0, but a value equal to or greater than 0 that is set in advance by design or experiment may also be used.

[0027] If the determination in S40 is positive, then in S50, an engine control command signal Se is sent to the engine control device 50 and an MG control command signal Smg is sent to the inverter 52 so that the engine 12 is stopped and evacuation travel is performed using the power of the electric motor MG2 alone, and this routine is terminated. On the other hand, if the determination in S40 is negative, then in S60, an engine control command signal Se is sent to the engine control device 50 and an MG control command signal Smg is sent to the inverter 52 so that evacuation travel is performed using the power of the engine 12 and the electric motor MG2, and this routine is terminated.

[0028] As described above, according to this embodiment, when an abnormality occurs in the actual engine output Pe and the average value Pav of the actual engine output Pe for the predetermined period TS is less than a predetermined threshold value TH that is equal to or greater than 0, the engine 12 is stopped and evacuation travel is performed using power from only the second electric motor MG2, and when the average value Pav is equal to or greater than the threshold value TH, the evacuation travel is performed using power from both the engine 12 and the second electric motor MG2. As a result, when an output abnormality occurs in the engine 12 and the average value Pav is equal to or greater than the threshold value TH, the engine 12 is driven without being stopped, thereby reducing power consumption (decrease in charge amount) of the battery 54 by the second electric motor MG2 and enabling the travel distance during evacuation travel to be extended.

[0029] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0030] For example, in the above-described embodiment, the vehicle 10 was a hybrid vehicle equipped with an engine 12, a first electric motor MG1, and a second electric motor MG2, but the present invention can be applied to any hybrid vehicle that can run on power from the electric motors alone, regardless of the number or configuration of the electric motors installed.

[0031] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0032] 10: Vehicle (hybrid vehicle) 12: Engine 90: Electronic control unit (control unit) MG2: Second electric motor (electric motor) Pav: Average value Pe: Actual engine output (engine output) TH: Threshold value TS: Predetermined period

Claims

[Claim 1] A control device for a hybrid vehicle powered by an engine and an electric motor, When an abnormality occurs in the engine output, the vehicle performs evacuation running using at least the power of the electric motor, When an abnormality occurs in the engine output and an average value of the engine output for a predetermined period is less than a predetermined threshold value that is equal to or greater than 0, the engine is stopped and the evacuation running is performed using power from the electric motor alone, and when the average value is equal to or greater than the threshold value, the evacuation running is performed using power from the engine and the electric motor. A control device for a hybrid vehicle.

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