Engine operation state estimation method and engine operation state estimation device

Abstract

Provided is a method for estimating the engine operation state of a vehicle provided with a generator, a power transmission mechanism, and an engine for driving the generator via the power transmission mechanism, wherein: torque of the power transmission mechanism is calculated, on the basis of a torque command value of the generator and an angular velocity of the generator, so as to include an influence of disturbance acting on the engine; and output torque of the engine is estimated on the basis of the angular velocity of the generator and the torque of the power transmission mechanism.

Description

Engine operating condition estimation method and engine operating condition estimation device

[0001] The present invention relates to an engine operating state estimation method and an engine operating state estimation device.

[0002] 2. Description of the Related Art There is known a device for estimating an engine's operating state, such as engine output torque or abnormal combustion (see, for example, Patent Document 1).

[0003] JP 2008-57492 A

[0004] The misfire detection device (engine operating state estimation device) described in Patent Document 1 calculates the influence torque component of a damper that affects the torque of the crankshaft and uses the influence torque component to determine engine misfire. However, the method for setting the constants in the calculation formula for the influence torque component is uncertain, and the device is affected by external disturbances such as friction due to the viscosity of engine oil changing with temperature, making it difficult to accurately estimate the operating state of the engine.

[0005] An object of the present invention is to provide an engine operating state estimation method and an engine operating state estimation device that can improve the accuracy of estimating the engine operating state.

[0006] In one aspect of the present invention, the torque of a power transmission mechanism is calculated based on a torque command value of a generator and the angular velocity of the generator so as to include the influence of disturbances acting on an engine, and the output torque of the engine is estimated based on the angular velocity of the generator and the torque of the power transmission mechanism.

[0007] In one aspect of the present invention, the torque of a power transmission mechanism is calculated based on a torque command value of a generator and the angular velocity of the generator so as to include the influence of disturbances acting on the engine, a state quantity for determining abnormal combustion of the engine is calculated based on the angular velocity of the generator and the torque of the power transmission mechanism, and it is estimated that the engine is in an abnormal combustion state based on the state quantity for determining abnormal combustion.

[0008] FIG. 1 is a diagram showing a schematic configuration of a vehicle. FIG. 2 is a schematic diagram showing the configuration of a power transmission mechanism. FIG. 3 is a control block diagram of a controller according to a first embodiment. FIG. 4 is a diagram showing the actual operating state and estimated operating state of the engine when abnormal combustion is not occurring. FIG. 5 is a flowchart of engine output torque estimation executed by the controller. FIG. 6 is a control block diagram of a controller according to a second embodiment. FIG. 7 is a diagram showing the relationship between torque and torsion angle of the power transmission mechanism. FIG. 8 is a diagram showing the actual operating state and estimated operating state of the engine when abnormal combustion is occurring. FIG. 9 is a control block diagram of a controller according to a third embodiment.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the second and subsequent embodiments, components that are the same as those in the previously described embodiments will be assigned the same numbers as those components or will not be shown in the drawings, and their description will be simplified or omitted.

[0010] 1 is a diagram showing a schematic configuration of a vehicle 1. The vehicle 1 includes an engine 11, a power transmission mechanism 12, a generator 13, a battery 14, an inverter 15, an electric motor 16, a reduction gear 17, wheels 18, and a control device 19.

[0011] The vehicle 1 is a so-called series-type hybrid vehicle in which electricity generated by a generator 13 using the power of an engine 11 is supplied to a battery 14 via an inverter 15, and wheels 18 are driven by rotating an electric motor 16 based on the power from the battery 14.

[0012] The engine 11 is an internal combustion engine that uses gasoline or the like as fuel, and is mechanically connected to a generator 13 via a power transmission mechanism 12. The engine 11 is used not as a power source for propelling the vehicle 1, but as a power source for driving the generator 13 to generate electricity.

[0013] The power transmission mechanism 12 transmits the output torque of the engine 11 (hereinafter referred to as engine torque) to the generator 13. The power transmission mechanism 12 includes a damper 12A and a speed increaser 12B (see FIG. 2). The damper 12A is connected to the output shaft 11A of the engine 11 and the speed increaser 12B, and reduces fluctuations in the engine torque before transmitting it to the generator 13. The speed increaser 12B includes a plurality of gears that mesh with each other.

[0014] The generator 13 is configured to generate electricity by rotating using power from the engine 11 and charge the battery 14. The generator 13 is also rotated using the power of the battery 14 to rotate the engine 11 (the engine 11 rotates together by controlling the rotation speed of the generator 13). By rotating the engine 11 using the power of the generator 13, it is possible to crank the engine 11 when starting the engine 11, to consume energy by rotating the generator 13 using the engine 11 as a load when the SOC (State of Charge) indicating the charge rate of the battery 14 is high, and to close the throttle valve to generate negative pressure in the intake passage when negative pressure for brake pedal assist is required.

[0015] The reducer 17 includes a transmission 17A and a differential gear 17B, and reduces the output of the electric motor 16 before transmitting it to the wheels 18.

[0016] The control device 19 includes an accelerator position sensor 19A as an accelerator operation amount sensor, a vehicle speed sensor 19B, angular velocity sensors 19C, 19D, and 19E, a drive system controller 20, and a power generation system controller 30. The control device 19 of this embodiment also functions as an engine operating state estimation device that estimates engine torque as the operating state of the engine 11.

[0017] The accelerator position sensor 19A is configured by, for example, a pedal stroke sensor, and detects the amount of operation of an accelerator pedal (hereinafter referred to as accelerator operation amount) as a driving force request operation means.

[0018] The vehicle speed sensor 19B is configured, for example, by a rotation speed sensor of the wheels 18, and detects the speed of the vehicle 1 (hereinafter referred to as vehicle speed).

[0019] The angular velocity sensor 19C is configured by, for example, an engine rotation speed sensor, and detects the angular velocity of the output shaft 11A of the engine 11 (see FIG. 2).

[0020] The angular velocity sensor 19D is configured by, for example, a resolver or an encoder, and detects the angular velocity of the rotating shaft 13A of the generator 13 (see FIG. 2) (hereinafter referred to as the angular velocity of the generator 13).

[0021] The angular velocity sensor 19E is configured by, for example, a resolver or an encoder, and detects the angular velocity of the rotating shaft of the electric motor 16 (hereinafter referred to as the angular velocity of the electric motor 16).

[0022] The drivetrain controller 20 and the power generation controller 30 are each configured by a microcomputer including, for example, a computing unit such as a CPU (Central Processing Unit) or a GPU (Central Graphics Processing Unit), a storage unit such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input / output unit such as an input / output interface. An accelerator position sensor 19A and a vehicle speed sensor 19B are electrically or communicatively connected to the drivetrain controller 20. Angular velocity sensors 19C, 19D, and 19E and the drivetrain controller 20 are electrically or communicatively connected to the power generation controller 30.

[0023] Based on the accelerator operation amount and the vehicle speed, the drive system controller 20 calculates a target value of the drive torque (hereinafter referred to as target drive torque) required to drive the vehicle 1. The drive system controller 20 outputs the calculated target drive torque to the inverter 15 as a torque command value for the electric motor 16, and also outputs it to the power generation system controller 30. If the SOC is at a fully charged value, the battery 14 cannot be charged, and so the regenerative energy of the electric motor 16 is consumed as friction by controlling the rotation speed of the generator 13, which rotates along with the engine 11.

[0024] The power generation system controller 30 receives a rotation speed command value and a torque command value for the generator 13 from a higher-level controller, and performs rotation speed control or torque control of the generator 13 depending on the situation. For example, when the engine 11 is powered, the power generation system controller 30 outputs a command to the engine 11 to cut fuel injection of the engine 11 as necessary. The power generation system controller 30 also estimates engine torque based on the torque command value for the generator 13 and the angular velocity of the generator 13.

[0025] 3 is a control block diagram of the power generation system controller 30. As shown in FIG. 3, the power generation system controller 30 includes a storage unit 31, an engine command setting unit 32, an engine operating state determination unit 33, a transmission mechanism torque calculation unit 34, and an engine torque estimation unit 35.

[0026] The memory unit 31 stores a computer program for causing the power generation system controller 30 to function, various maps used for control, various thresholds, etc. The maps stored in the memory unit 31 include, for example, a map that defines the relationship between accelerator operation amount, vehicle speed, and driving force, and a map that associates a required power value with a target output torque or target rotation speed of the engine 11.

[0027] The engine command setting unit 32 sets commands for the engine 11, such as a target output torque, a target rotation speed, and a fuel cut request for the engine 11, based on a torque command value for the electric motor 16. For example, the engine command setting unit 32 converts the torque command value for the electric motor 16 into a required power value, and sets a target output torque and a target rotation speed for the engine 11 corresponding to the required power value. Furthermore, the engine command setting unit 32 sets a fuel cut command for the engine 11 based on, for example, the required power value obtained by converting the torque command value for the electric motor 16 and the SOC of the battery 14, and outputs the fuel cut command to the engine 11.

[0028] The engine operating condition determination unit 33 determines whether the operating condition is unsuitable for estimating the engine torque. In this embodiment, the engine operating condition determination unit 33 determines whether a fuel cut is being performed on the engine 11 and whether the engine 11 is starting.

[0029] The transfer mechanism torque calculation unit 34 calculates the torque of the power transfer mechanism 12 (hereinafter referred to as transfer mechanism torque) including the influence of disturbances acting on the engine 11, based on the torque command value of the generator 13 and the angular velocity of the generator 13. The transfer mechanism torque calculation unit 34 is a disturbance observer for the torque of the generator 13, and calculates transfer mechanism torque that reflects the influence of disturbances acting on the engine 11 and the influence of disturbances acting on the power transfer mechanism 12, as disturbances acting on the torque of the generator 13.

[0030] Specifically, as shown in FIG. 3, the transmission mechanism torque calculation unit 34 calculates the transmission mechanism torque from the difference between a value obtained by applying a torque command value of the generator 13 through a low-pass filter of H1(s) and a value obtained by applying a low-pass filter to the angular velocity ωm of the generator 13 through H1(s) and then dividing the result by the transfer characteristic Gp'(s) of the generator 13.

[0031] The transfer mechanism torque is not incorporated in advance into the transfer characteristic Gp'(s) of the generator 13, i.e., the transfer characteristic Gp'(s) between the torque command value of the generator 13 and the angular velocity of the generator 13. This is because the transfer mechanism torque fluctuates depending on the input power and also behaves differently depending on the operating conditions of the engine 11, the temperature, the viscosity of the engine oil, etc. Therefore, the transfer mechanism torque acts as a disturbance on the torque of the generator 13.

[0032] The transfer characteristic Gp'(s) of the generator 13 is set to Gp'(s) = 1 ÷ (Jm·s), where Jm is the inertia of the engine 11 and s is the Laplace operator. The original transfer characteristic Gp(s) of the generator 13 is expressed as Gp(s) = 1 ÷ (Jall·s + C), where Jall is the total value of the inertia of the engine 11, the power train 12, and the generator 13; however, Gp'(s) does not take into account the inertia of the power train 12 and the generator 13. In this way, the influence of disturbances acting on the engine 11 and the power train 12 is reflected in the transfer mechanism torque.

[0033] The engine torque estimation unit 35 estimates the engine torque based on the angular velocity of the generator 13 and the transmission mechanism torque.

[0034] The equation of motion of the engine 11 around the output shaft 11A is expressed by the following equation (1), where the inertia and angular velocity of the engine 11 are Je and ωe, the engine torque is Te, the transmission mechanism torque is Td, the gear ratio of the power transmission mechanism 12 is N, and the angular velocity of the generator 13 is ωm.

[0035]

[0036] After Laplace transforming equation (1), the following equation (2) is obtained by converting it so that the angular velocity ωm of the generator 13 and the transmission mechanism torque Td are input, where s is the Laplace operator.

[0037]

[0038] As shown in FIG. 3, the engine torque estimation unit 35 is configured to calculate the engine torque according to equation (2).

[0039] 4 is a diagram showing the actual operating state and the estimated operating state of the engine 11 when no abnormal combustion is occurring. As shown in FIG. 4, the transmission mechanism torque is estimated by calculation, and the engine torque is estimated using this transmission mechanism torque. The estimated engine torque coincides with the actual engine torque with high accuracy.

[0040] 5 is a flowchart showing the engine torque estimation process executed by the power generation controller 30. The processing routine shown in this flowchart is pre-programmed, and this program is installed in the power generation controller 30. In accordance with the program, the power generation controller 30 repeatedly executes the following control routine at an operation cycle of, for example, about 10 milliseconds.

[0041] In step S1 of FIG. 5, the power generation system controller 30 acquires various detection values ​​of the sensors 19A to 19E and various command values ​​such as a torque command value.

[0042] In the following step S2, the engine operating condition determination unit 33 determines whether a fuel cut is being performed on the engine 11 and whether the engine 11 is starting. If it is determined in step S2 that the engine 11 is in a fuel cut state or is starting, the process returns to step S1 without estimating engine torque. During fuel cut or starting, the changes in the transmission mechanism torque and the angular velocity of the generator 13 become large. Therefore, if these values ​​are differentiated by H2(s) shown in FIG. 3 when estimating engine torque, overflow may occur during calculation, resulting in a value being lost. For this reason, during fuel cut or starting of the engine 11, estimation of engine torque is stopped.

[0043] On the other hand, if it is determined in step S2 that the engine 11 is not in the fuel cut or startup state, the process proceeds to step S3. In step S3, the transmission mechanism torque calculation unit 34 calculates the transmission mechanism torque based on the torque command value of the generator 13 and the angular velocity of the generator 13.

[0044] In the following step S4, the engine torque estimation unit 35 estimates the engine torque based on the angular velocity of the generator 13 and the transmission mechanism torque. The estimated engine torque is used, for example, for control, determination, or other estimation in the power generation system controller 30, or is transmitted to another controller such as the drive system controller 20 or an engine controller and used for control, determination, or estimation in the other controller.

[0045] According to the embodiment described above, the transmission mechanism torque including the influence of disturbances acting on the engine 11 is calculated, and the engine torque is estimated based on the angular velocity of the generator 13 and the transmission mechanism torque. Therefore, the engine torque can be estimated taking into account the influence of disturbances, and the estimation accuracy of the operating state of the engine 11 can be improved.

[0046] Furthermore, when the engine 11 is being cut off from fuel or when it is being started, the estimation of the engine torque is stopped, so that the accuracy of the estimation of the engine torque can be prevented from decreasing.

[0047] 6 is a control block diagram of a power generation controller 30A according to the second embodiment. The power generation controller 30A estimates that the engine 11 is in an abnormal combustion state. The control device 19 according to the second embodiment, which includes the power generation controller 30A, also functions as an engine operating state estimation device that estimates that the engine 11 is in an abnormal combustion state as the operating state of the engine 11.

[0048] The power generation system controller 30A includes a storage unit 31, an engine command setting unit 32, a transmission mechanism torque calculation unit 34, a state quantity calculation unit for determination 36, and an abnormal combustion state estimation unit 37.

[0049] The state quantity for determination calculation unit 36 ​​calculates a state quantity for determining abnormal combustion of the engine 11 based on the angular velocity of the generator 13 and the transmission mechanism torque. In the present embodiment, the state quantity for determination calculation unit 36 ​​calculates the torsion angle of the damper 12A included in the power transmission mechanism 12 as the state quantity for determining abnormal combustion.

[0050] The damper 12A has, for example, the characteristics shown in Fig. 7, and its torque changes depending on the torsional angle. The torsional rigidity of the damper 12A is expressed by the slope of the torque with respect to the torsional angle. Fig. 7 shows a plurality of characteristics having different torsional rigidities depending on the torsional angle.

[0051] The transmission mechanism torque is generated mainly by the torsion of the damper 12A, and is therefore expressed by the following equation (3), where Td is the transmission mechanism torque, Kd is the torsional rigidity of the damper 12A, ωe is the angular velocity of the engine 11, N is the gear ratio of the power transmission mechanism 12, and ωm is the angular velocity of the generator 13.

[0052]

[0053] From equation (3), the torsional angle of the damper 12A can be obtained by integrating (Nωm−ωe), which corresponds to the torsional angular velocity of the damper 12A.

[0054] The abnormal combustion state estimation unit 37 estimates that the engine 11 is in an abnormal combustion state based on the state quantities for determining abnormal combustion. In this embodiment, the abnormal combustion state estimation unit 37 estimates that the engine 11 is in an abnormal combustion state based on the torsion angle of the damper 12A.

[0055] FIG. 8 is a diagram showing the actual operating state and the estimated operating state of the engine 11 when abnormal combustion is occurring. As shown in FIG. 8 , the abnormal combustion state estimation unit 37 estimates that the engine 11 is experiencing abnormal combustion when the amount of fluctuation in the transmission mechanism torque during a predetermined time T exceeds a threshold value TH1 and the amount of fluctuation in the torsion angle of the damper 12A exceeds a threshold value TH2. On the other hand, as shown in FIG. 4 , the abnormal combustion state estimation unit 37 does not estimate that the engine 11 is experiencing abnormal combustion when the amount of fluctuation in the transmission mechanism torque during the predetermined time T is equal to or less than the threshold value TH1 and the amount of fluctuation in the torsion angle of the damper 12A is equal to or less than the threshold value TH2. The amount of fluctuation in the transmission mechanism torque is the difference between the maximum and minimum values ​​of the transmission mechanism torque during the predetermined time T, and the amount of fluctuation in the torsion angle of the damper 12A is the difference between the maximum and minimum values ​​of the torsion angle during the predetermined time T. The threshold values ​​TH1 and TH2 of the fluctuation amounts are set taking into account friction, damping characteristics, or variations in the stiffness of the damper 12A when the engine 11 is not experiencing abnormal combustion. In this embodiment, the threshold values ​​TH1 and TH2 are set to lower limit values ​​in design taking into consideration the friction, damping characteristics, or stiffness variations of the damper 12A when the engine 11 is not undergoing abnormal combustion.

[0056] According to the embodiment described above, the state quantities for determining abnormal combustion of the engine 11 are calculated based on the angular velocity of the generator 13 and the transmission mechanism torque including the influence of external disturbances acting on the engine 11, and it is estimated that the engine 11 is in an abnormal combustion state based on the state quantities for determining abnormal combustion. Therefore, it is possible to estimate that the engine 11 is in an abnormal combustion state taking into account the influence of external disturbances, and the accuracy of estimating the operating state of the engine 11 can be improved.

[0057] In addition, since the engine 11 is connected to the output shaft 11A of the engine 11 and is easily affected by abnormal combustion of the engine 11, it is estimated that the engine 11 is in an abnormal combustion state based on the torsion angle of the damper 12A, which is easily affected by abnormal combustion of the engine 11, thereby improving the accuracy of estimating the abnormal combustion state.

[0058] Furthermore, when the amount of fluctuation in the transmission mechanism torque and the amount of fluctuation in the torsion angle of the damper 12A exceed the respective threshold values ​​TH1 and TH2, it is estimated that the engine 11 is in an abnormal combustion state, which makes it possible to more reliably estimate that the engine 11 is in an abnormal combustion state. The respective threshold values ​​TH1 and TH2 for the amount of fluctuation are set taking into consideration the friction, damping characteristics, and stiffness variations of the damper 12A when the engine 11 is not in abnormal combustion, so it is possible to estimate that the engine 11 is in an abnormal combustion state based on the characteristics of the engine 11 and the damper 12A.

[0059] 9 is a control block diagram of a power generation controller 30B of this embodiment. The power generation controller 30B references the time transition of the estimated engine torque and estimates that the engine 11 is in an abnormal combustion state. The control device 19 of this embodiment, which is equipped with the power generation controller 30B, also functions as an engine operating state estimation device that estimates that the engine 11 is in an abnormal combustion state as the operating state of the engine 11.

[0060] The power generation system controller 30B includes a memory unit 31, an engine command setting unit 32, an engine operating condition determination unit 33, a transmission mechanism torque calculation unit 34, an engine torque estimation unit 35, and an abnormal combustion state estimation unit 37.

[0061] The storage unit 31 stores in advance, for example, the time transition waveform of the engine torque when there is no abnormal combustion (see FIG. 4 ).The storage unit 31 also stores, for example, the time transition waveform of the engine torque when idling and the time transition waveform of the engine torque when the engine speed is kept approximately constant while traveling.

[0062] In this embodiment, the engine torque estimation unit 35 also functions as a state quantity calculation unit for determination. The engine torque estimation unit 35 calculates the engine torque as a state quantity for determining abnormal combustion based on the angular velocity of the generator 13 and the power transmission mechanism torque.

[0063] In this embodiment, the abnormal combustion state estimation unit 37 estimates that the engine 11 is experiencing abnormal combustion if the time progression of the engine torque calculated in 35 differs from the time progression waveform of the engine torque stored in the memory unit 31.

[0064] For example, if any cylinder of the engine 11 is misfiring, as shown in Figure 8, the engine torque does not increase at the combustion timing of the cylinder, and falls below the engine torque when no abnormal combustion is occurring, for example, as shown in Figure 4. Therefore, the abnormal combustion state estimation unit 37 estimates that a misfire has occurred in the corresponding cylinder when the engine torque falls below the stored engine torque at the combustion timing of the cylinder.

[0065] On the other hand, if the engine 11 knocks or auto-ignites unintentionally before ignition by the spark plug, the engine torque exceeds the engine torque when no abnormal combustion occurs at the combustion timing of the cylinder. Therefore, the abnormal combustion state estimation unit 37 estimates that the engine 11 is knocking or auto-igniting before ignition when the engine torque exceeds the stored engine torque at the combustion timing of the cylinder.

[0066] According to the embodiment described above, the engine torque waveform over time can be compared with the waveform when abnormal combustion is not occurring to estimate whether the engine 11 is in an abnormal combustion state, thereby improving the accuracy of estimating the abnormal combustion state.

[0067] Furthermore, if the engine torque is lower than the stored engine torque at the combustion timing of the cylinder, it is estimated that the cylinder is misfiring, and if it is higher, it is estimated that the engine 11 is knocking or has self-ignited before ignition, so that the type of abnormal combustion of the engine 11 can be estimated.

[0068] As described above, the best configurations, methods, and the like for implementing the present invention have been disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been particularly illustrated and described mainly with reference to specific embodiments, those skilled in the art can make various modifications to the above-described embodiments in terms of shape, material, quantity, and other detailed configurations without departing from the scope of the technical idea and purpose of the present invention. Furthermore, the above-disclosed descriptions limiting the shape, material, and the like are provided as examples to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, descriptions using names of components that are free from some or all of the limitations on shape, material, and the like are included in the present invention.

[0069] In the power transmission mechanism 12, the damper 12A may be connected to the output shaft 11A of the engine 11 and the speed increaser 12B may be connected to the rotating shaft 13A of the generator 13, or the damper 12A may be connected to the rotating shaft 13A of the generator 13 and the speed increaser 12B may be connected to the output shaft 11A of the engine 11. The power transmission mechanism 12 may or may not include the damper 12A. The damper 12A may have only one torsional stiffness characteristic, that is, a characteristic represented by a single straight line with the slope of the torque relative to the torsional angle, or may have a characteristic with multiple torsional stiffnesses.

[0070] In the control device 19, the driving force request operation means is configured as an accelerator pedal, and the accelerator operation amount sensor is configured as an accelerator position sensor 19A, but other configurations may be used. For example, the driving force request operation means may be configured as an operation lever or an operation dial, and the accelerator operation amount sensor may be configured as a sensor such as a stroke sensor or potentiometer that detects the amount of operation of these. The vehicle speed sensor 19B is not particularly limited, and may be, for example, a ground speed sensor.

[0071] The drive system controller 20 and the power generation system controller 30 may be configured as a single computer having both, or may be configured as separate computers.

[0072] The transmission mechanism torque calculation unit 34 may calculate the transmission mechanism torque regardless of whether the power transmission mechanism 12 includes the damper 12A. When estimation of the engine torque is stopped during fuel cut of the engine 11 or when the engine 11 is started, the transmission mechanism torque calculation unit 34 may or may not calculate the transmission mechanism torque.

[0073] The abnormal combustion state estimation unit 37 may integrate the amount of fluctuation in the transmission mechanism torque and the amount of fluctuation in the torsion angle of the damper 12A, and when the integrated value exceeds each threshold, estimate that abnormal combustion is occurring in the engine 11. The abnormal combustion state estimation unit 37 may also filter the amount of fluctuation in the transmission mechanism torque and the amount of fluctuation in the torsion angle of the damper 12A, and when the filtered fluctuation amount exceeds each threshold, estimate that abnormal combustion is occurring in the engine 11.

[0074] 1...vehicle, 11...engine, 12...power transmission mechanism, 12A...damper, 13...generator, 19...controller (engine operating state estimation device), 20...drive system controller, 30...power generation system controller (controller)

Claims

1. A method for estimating the engine operating state of a vehicle equipped with a generator, a power transmission mechanism, and an engine that drives the generator via the power transmission mechanism, the method comprising: calculating the torque of the power transmission mechanism based on a torque command value of the generator and the angular velocity of the generator so as to include the influence of disturbances acting on the engine; and estimating the output torque of the engine based on the angular velocity of the generator and the torque of the power transmission mechanism.

2. The engine operating state estimation method according to claim 1, wherein estimation of the engine output torque is stopped when the engine is fuel cut or when the engine is started.

3. A method for estimating the engine operating state of a vehicle equipped with a generator, a power transmission mechanism, and an engine that drives the generator via the power transmission mechanism, the method comprising: calculating the torque of the power transmission mechanism based on a torque command value of the generator and the angular velocity of the generator so as to include the influence of disturbances acting on the engine; calculating a state quantity for determining abnormal combustion of the engine based on the angular velocity of the generator and the torque of the power transmission mechanism; and estimating that the engine is in an abnormal combustion state based on the state quantity for determining abnormal combustion.

4. A method for estimating an engine operating state as set forth in claim 3, wherein the torsion angle of a damper included in the power transmission mechanism is calculated as a state quantity for determining abnormal combustion based on the torque of the power transmission mechanism, and the engine is estimated to be in an abnormal combustion state based on the torsion angle of the damper.

5. A method for estimating an engine operating state as set forth in claim 4, wherein the engine is estimated to be undergoing abnormal combustion when the amount of fluctuation in the torque of the power transmission mechanism and the amount of fluctuation in the torsion angle of the damper exceed their respective threshold values.

6. A method for estimating an engine operating state according to claim 5, wherein the threshold values ​​for the amount of torque fluctuation in the power transmission mechanism and the amount of fluctuation in the torsion angle of the damper are set to lower limit values ​​that take into account friction, damping characteristics, or variations in stiffness of the damper when the engine is not undergoing abnormal combustion.

7. A method for estimating an engine operating state as set forth in claim 3, wherein a time-varying waveform of the engine output torque when the engine is not undergoing abnormal combustion is stored, the output torque of the engine is calculated as a state quantity for determining abnormal combustion based on the angular velocity of the generator and the torque of the power transmission mechanism, and when the time-varying waveform of the estimated output torque of the engine differs from the stored time-varying waveform of the output torque, the method estimates that the engine is undergoing abnormal combustion.

8. A method for estimating an engine operating state according to claim 7, wherein when the output torque of the engine is lower than a stored output torque at the combustion timing of a cylinder, it is estimated that the cylinder is misfiring.

9. A method for estimating an engine operating state as set forth in claim 7, wherein, when the output torque of the engine exceeds a stored output torque at the cylinder combustion timing, it is estimated that the engine is knocking or auto-igniting before ignition.

10. An engine operating state estimating device for a vehicle equipped with a generator, a power transmission mechanism, and an engine that drives the generator via the power transmission mechanism, the engine operating state estimating device including a controller that calculates the torque of the power transmission mechanism based on a torque command value of the generator and the angular velocity of the generator so as to include the influence of disturbances acting on the engine, and that estimates the output torque of the engine based on the angular velocity of the generator and the torque of the power transmission mechanism.

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