Single-cylinder engine misfire detection device, method, and vehicle

Abstract

Misfire detection device for a single-cylinder engine, comprising: means (4a, 4b) for detecting an angular velocity at each crankshaft angle from an inter-crankshaft pulse period; Means (7b) for calculating a relative angular velocity at each crankshaft angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and the vicinity of an exhaust top dead center of the engine based on the angular velocity at each crankshaft angle; Means (8b) for integrating the relative angular velocity within a given crankshaft angle range to calculate an integration angular velocity for each of an expansion stroke and an intake stroke; and Misfire parameter calculating means (10b) for calculating an integration angular velocity resulting from the combustion torque from the integration angular velocity, the reference angular velocity and a specifically detected pumping torque component and for determining the calculated integration angular velocity as a misfire parameter, wherein The calculation tools for misfire parameters include: means for removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an expansion stroke to calculate a first integration angular velocity after the removal; means for removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an intake stroke to calculate a second integration angular velocity after the removal; and Means for subtracting the second integration angular velocity after the removal corrected with a ratio between the reference angular velocities in the expansion stroke and the intake stroke from the first integration angular velocity after the removal to determine a misfire parameter.

Description

Technical FieldThe present invention relates to a single cylinder engine misfire detection device and method and a single cylinder engine vehicle, and more particularly to a single cylinder engine misfire detection device and method and a single cylinder engine vehicle capable of executing misfire detection with high accuracy without measuring inter-tooth failure of a crankshaft pulse rotor for each vehicle using a property of a single cylinder engine.BackgroundIn a four-wheel vehicle, a technology is known that determines misfire of an engine based on a crankshaft angular velocity measured from the time intervals of crankshaft pulse generation (crankshaft pulse time intervals). Since a misfire decision characteristic (misfire characteristic) includes an angular velocity component resulting from an inter-tooth failure of a crankshaft pulse rotor in order to make an accurate misfire decision, it is necessary to eliminate an inter-tooth failure.JP 2008111 354 A discloses a technology that calculates a relative angular velocity of each crankshaft angle with respect to a reference angular velocity detected in the vicinity of the compression top dead center of an engine based on a crankshaft velocity, and uses an integrated value of such relative angular velocities as a misfire parameter.JP 2014 199 040 A discloses a technology that calculates a difference of the change value of the crankshaft angular velocity for each cylinder of the single cylinder engine and uses the value of the difference as a misfire parameter, so that an angular velocity component resulting from an inter-tooth error of a crankshaft pulse rotor is removed from the misfire parameter.DE 60 2005 003 914 T2 discloses a device for detecting mistransmissions and the cylinder causing the misfire in an internal combustion engine having a plurality of cylinders. A crank angular velocity is detected in the internal combustion engine for each predetermined angular range and periodic functions are set, so that generation of a torque for each cylinder can be modeled in synchronization with a complete combustion cycle of the internal combustion engine (720° crank angle). On the basis of an analysis of the periodic functions and the ascertained crankshaft angular velocity, a value is calculated which is integrated over a specific angular range. A moving average is then determined to determine a correlation function. The integrated value is compared with a threshold value to determine the occurrence of misfire.DE 197 13 104 A1 describes an engine combustion state judging method for detecting a crank angle speed of a multi-cylinder engine, judging a combustion state of each of the cylinders of the engine based on the detection of the crank angle speed, the judging method comprises setting a predetermined crank angle range selectively determined within a range between a crank angle at which combustion in a given cylinder substantially ends and another crank angle at which combustion in the next cylinder substantially starts to detect a crank angle speed characteristic, and judging the combustion state based on the crank angle speed characteristic within the predetermined crank angle range.SummaryTechnical ProblemIn recent years, in view of improving repairability and environmental protection, introduction of misfire technology is also studied in a motorcycle (motorcycle). In a motorcycle, the requirement of the variety for performance or property of an engine, an explosion engine of uneven intervals, or a single cylinder engine is adopted.Since the inter-tooth failure elimination method for a crankshaft pulse rotor in JP 2008-111 354 A is a technology utilizing a characteristic of an explosion engine of non-uniform control, it cannot be applied to a single cylinder engine. The misfire detection technique of JP 2014-199 040 A cannot remove an angular velocity component resulting from pumping torque, load torque generated within one cycle, and a friction change.The object of the present invention is to provide a single cylinder engine misfire detection apparatus and method and a single cylinder motor vehicle which remove an angular velocity component resulting from an inter-tooth error of a crankshaft pulse rotor from a misfire parameter without measuring an inter-tooth error of the crankshaft pulse rotor in the single cylinder engine, so that misfire detection can be performed with high accuracy.Means for Solving the ProblemThe object is achieved by the features of the independent claims. Advantageous further developments of the invention are described in the dependent claims. A misfire detecting apparatus for a single cylinder engine of the present invention comprises means (4a, 4b) for detecting an angular velocity at each crank angle from an intermediate crank pulse time period, means (7b) for calculating a relative angular velocity at each crank angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and the vicinity of an exhaust top dead center of the engine on the basis of the angular velocity at each crank angle, means (8b) for integrating the relative angular velocity within a given crank angle range for calculating an integration angular velocity for each of an expansion stroke and an intake stroke; and misfire parameter calculating means (10b) for calculating an integration angular velocity resulting from the combustion torque of the integration angular velocity, the reference angular velocity and a specially detected pumping torque component, and determining the calculated integration angular velocity as a misfire parameter.The misfire parameter calculation means includes means for removing an integration angular velocity component arising from the pumping torque of the integration angular velocity in an expansion stroke to calculate a first integration angular velocity after the removal, means for removing an integration angular velocity component arising from the pumping torque of the integration angular velocity in an intake stroke to calculate a second integration angular velocity after the removal; and means for subtracting the second integration angular velocity after the removal corrected with a relationship between the reference angular velocities in the expansion stroke and the intake stroke to determine a misfire parameter from the first integration angular velocity after the removal.A misfire detection method for a single cylinder engine of the present invention comprises detecting an angular velocity at each crank angle from an intermediate crank pulse time period, calculating a relative angular velocity at each crank angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and the vicinity of an exhaust top dead center of the engine based on the angular velocity at each crank angle, integrating the relative angular velocity within a given crank angle range to calculate an integration angular velocity for each expansion stroke and each intake stroke; and calculating an integration angular velocity resulting from the combustion torque, the integration angular velocity, the reference angular velocity, and a specially detected pumping torque component, and determining the calculated integration angular velocity as a misfire parameter.A vehicle in which a single cylinder engine of the present invention is integrated includes means for detecting an angular velocity at each crank angle from an inter-crank pulse time period, means for calculating a relative angular velocity at each crank angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and the vicinity of an exhaust top dead center of the engine based on the angular velocity at each crank angle, means for integrating the relative angular velocity within a given crank angle range to calculate an integration angular velocity for each expansion stroke and each intake stroke; and the misfire parameter calculating means for calculating an integration angular velocity resulting from the combustion torque of the integration angular velocity, the reference angular velocity and a specially detected pumping torque component, and determining the calculated integration angular velocity as the misfire parameter.The misfire detection apparatus for a single cylinder engine further comprises means (6b) for removing a first angular velocity fluctuation component possibly occurring in a vehicle-mounted engine from a result of detecting the angular velocity, wherein the relative angular velocity calculating means calculates a relative angular velocity aimed at an angular velocity from which the first angular velocity fluctuation component is removed.The first angular velocity fluctuation component is an angular velocity fluctuation component resulting from the load torque of a tire or an accessory of a vehicle driven by the engine and the friction of a sliding part of the engine.Advantageous Effects of the Invention(1) According to the misfire detection apparatus, method, and vehicle of the present invention, a misfire decision can be achieved with high accuracy because it becomes possible to remove an inter-tooth error component from a misfire parameter without measurement of the inter-tooth error of the crankshaft pulse rotor by utilizing the fact that, in a single cylinder engine, explosions occur only once during one cycle and the angular velocity at each crankshaft angle in an expansion stroke in which combustion torque is generated and an intake stroke in which combustion torque is not generated is measured at a same portion of a crankshaft pulse rotor.(2) Since misfire parameter calculation means removes the integration angular velocity component resulting from the pumping torque of the integration angular velocity in the expansion stroke to determine a first integration angular velocity after removal, removes the integration angular velocity component resulting from the pumping torque of the integration angular velocity in the intake stroke to determine a second integration angular velocity after removal, and subtracts the second integration angular velocity after removal, which is corrected with the relationship between the reference angular velocities in the expansion stroke and the intake stroke from the first integration angular velocity after removal to determine a misfire parameter, it becomes possible to remove the inter-tooth error component from the misfire parameter regardless of the angular velocity difference between the expansion stroke and the intake stroke.(3) Since the misfire detection apparatus for a single cylinder engine includes means for removing a first angular velocity variation component possibly occurring in a vehicle-mounted engine from the result of the determination of the angular velocity, and means for calculating a relative angular velocity includes a relative angular velocity aimed at the angular velocity from which the first angular velocity variation component is removed, it is possible to eliminate the influence of the first angular velocity variation components.(4) Since an angular velocity fluctuation component resulting from the load torque of a tire or an accessory of the engine-driven vehicle and the friction of a sliding part of the engine is removed as the first angular velocity fluctuation component, a misfire decision with high accuracy becomes possible.Brief Description of the DrawingsFIG. 1 is a block diagram illustrating a method and an apparatus for detecting misfire of a single cylinder engine and a single cylinder engine to which the present invention is applied. FIG. 2 illustrates a change in angular velocity when the continuous operation is performed in the engine body fuel-off state. FIG. 3 illustrates a function of a 720 degree filter. FIG. 4 illustrates a function of a relative angular velocity calculation unit. FIG. 5 illustrates a function of an integration angular velocity calculation unit. FIG. 6 illustrates an example of the calculation result of a moment of inertia determined by the desktop calculation. FIG. 7 illustrates a function of an inertia torque component extraction unit. FIG. 8 illustrates an example pumping torque component when the throttle value is fully closed. FIG. 9 illustrates a misfire detection method in which a relative angular velocity is determined from an angular velocity detected at each generation of a crank pulse and an integrated value of the relative angular velocity is determined as a misfire parameter (no misfire). FIG. 10 illustrates a misfire detection method in which a relative angular velocity is determined from an angular velocity detected at each generation of a crank pulse and an integrated value of the relative angular velocity is determined as a misfire parameter (misfire).DESCRIPTION OF THE EMBODIMENTHereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, an overview of a misfire detection method based on a crankshaft angular velocity and the present invention is given here, and then an embodiment of the present invention will be described in detail.FIGS. 9 and 10 are views illustrating an example of a misfire detection method in which, in a two-cylinder engine, a relative angular velocity is determined from an angular velocity detected at each generation of a crank pulse, and an integrated value of the relative angular velocity (integrated angular velocity) is determined as a misfire parameter. The relative angular velocity is calculated by subtracting a reference angular velocity detected near the compression top dead center of each cylinder of an engine from an angular velocity detected at each generation of a crankshaft pulse.Reference numerals #1 and #2 in FIGS. 9 and 10 denote cylinder names for identifying two cylinders according to an ignition order. FIG. 9 illustrates a case where the combustion in all the cylinders of #1 and #2 is normal. FIG. 10 illustrates a case where misfire occurs only in the cylinder of #1.While the relative angular velocity increases when the combustion is normally performed in a combustion stroke after the compression top dead center, the relative angular velocity decreases when a misfire occurs. The integration angular velocity obtained by the integration of the relative angular velocity within a predetermined crankshaft angular range indicates a positive value in the cylinder in which the combustion is normally performed, but indicates a negative value in the cylinder in which a misfire occurs. Accordingly, the integration angular velocity can be used as a parameter for the decision on a misfire cylinder.However, the integration angular velocity includes a varying angular velocity component resulting from, besides the combustion torque, inter-tooth failure of a crankshaft pulse rotor, noise caused by dynamic change of a sensor gap, load torque, friction, moment of inertia, pumping torque, etc. Therefore, in order to perform accurate misfire detection, it is necessary to remove all fluctuation components from the integration angular velocity.As for noise, load torques, friction and inertia torques from the above-described fluctuation components, a technique is known which removes them by statistical processing, motor control, desktop calculation, or the like. However, with respect to pumping torque, an effective removal method is not established.Pumping torque is torque generated by pumping motion of a piston in intake, compression, expansion, and exhaust strokes of an engine. Accordingly, the pumping torque is a parameter different from a pumping loss representing an energy loss occurring in the intake stroke and the exhaust stroke of the engine.In the present invention, for each vehicle model that performs misfire detection, an environment is prepared in which a standard vehicle Mref having an ideal crank pulse rotor in which a tooth error between the speeds is substantially zero is prepared in advance to eliminate an inter-tooth error component. Subsequently, fluctuation components other than the pumping torque are removed by the appropriate technique described above using the standard vehicle Mref to determine and extract an integration angular velocity at which the pumping torque component is dominant as the pumping torque component unique to the vehicle model, and then the determined pumping torque component is set as data to an electronic control unit (ECU) of each large-volume distribution vehicle. Thus, the pumping torque component may be removed from a misfire parameter.Since only one explosion occurs during one cycle in a single cylinder engine, the angular velocity can be measured at the same portion of the crankshaft pulse rotor at each crankshaft angle in the expansion stroke in which the combustion torque is generated and the intake stroke in which the combustion torque is not generated.An inter-tooth error component and an inertial torque component are included in the integration angular velocity (first integration angular velocity) with respect to a reference angular velocity detected in the vicinity of the compression top dead center, which is a starting point of an expansion stroke, and another integration angular velocity (second integration angular velocity) with respect to a reference angular velocity detected in the vicinity of the exhaust top dead center, which is a starting point of an intake stroke. However, the inter-tooth error components and the inertia torque components are proportional to the angular velocity. Thus, when an angular velocity difference between the strokes is corrected, the inter-tooth error components and inertia torque components included in the first integration angular velocity and the second integration angular velocity are equalized.When the difference between the first integration angular velocity and the second integration angular velocity whose angular velocity difference between the strokes is corrected is determined as the misfire parameter, the inter-tooth error components and the inertia moment components after the angular velocity correction are equal in the first and second integration angular velocities, and the inter-tooth error components and the inertia moment components are removed from the misfire parameter. The angular velocity fluctuation component resulting from the noise, the load torque, the friction, and the pumping torque included in the misfire parameter can be removed with the suitable technique described above. For this reason, in a single cylinder engine, misfire decision with high accuracy becomes possible without performing inter-tooth error measurement of a crank pulse for each vehicle.Now, the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a method and apparatus for detecting misfire in a single cylinder engine and a single cylinder engine vehicle to which the present invention is applied.A standard vehicle Mref includes a single cylinder engine E equipped with an ideal crankshaft pulse rotor 3ref mounted on a crankshaft 2 of the single cylinder engine E and having a substantially zero inter-tooth error between the transmissions, and an extraction device 100 for component extraction of pumping torque.In the pumping torque component extraction device 100, a crankshaft angular velocity measurement unit 5 ameasures the angular velocity in a state where the combustion torque is not substantially generated. Therefore, the interpulse period of the ideal crankshaft pulse rotor 3refin the fuel-off state of a crankshaft pulse sensor 4 ais measured to calculate an angular velocity at each crankshaft angle. A known moving averaging process or the like is applied to the angular velocity at each crank angle to remove noise components. FIG. 2 illustrates a change in angular velocity when steady-state operation is performed in a state with the fuel cut off in the machine frame.A 720-degree filter processing unit 6 abends a linear change within a cycle period aimed at a result of calculation of an angular velocity ω, and extracts a fluctuation component whose cycle is comparatively short. Consequently, an angular velocity fluctuation component resulting from the load torque applied from a tire or an accessory of the engine-driven vehicle or friction of a sliding part of the engine can be removed.FIG. 3 illustrates an example in which a 720-degree filter is applied to a cycle within which the speed is decreased by load torque although combustion torque is generated. Since a pumping torque component is extracted in the machine frame during stationary operation, the linear change in the angular velocity within one cycle is very small.Since vibration components are removed by the above-described filtering process in a state where the combustion torque is substantially zero, in the obtained angular velocity ω, substantially only vibration components by inertia moment and pumping torque are considered.A relative rotational speed calculation unit 7 acalculates, using the angular velocity ω (crankshaft angle 0 degrees) measured in the vicinity of the compression top dead center as the reference angular velocity ωlref, as illustrated in FIG. 4, the difference between an angular velocity ω 1_i measured at each crankshaft angle i within a crankshaft angular range of 180 degrees from the compression top dead center and the reference angular velocity ωlref as the first relative angular velocity ωω 1_i (=ω 1_i- ωlref).Also, using the angular velocity ω (crankshaft angle 360 degrees) measured in the vicinity of the exhaust top dead center as the reference angular velocity ω2ref, the difference between an angular velocity ω2_j measured in each crankshaft angle j within each crankshaft angular range of 180 degrees from the exhaust top dead center and the reference angular velocity ω2ref is calculated as the second relative angular velocity ωω2_j (=ω2_j - ω2ref).As illustrated in FIG. 5, an integration angle calculation unit 8 aintegrates the first and second relative angular velocities ωω1_i and ωω2_j to calculate a first integration angular velocity Σωω1_i and a second integration angular velocity Σωω2_j, respectively.An inertial torque component removal unit 9 aremoves inertial torque components determined by desktop calculation from the first and second integration angular speeds Σωω1_i and Σωω2_j to calculate a first integration angular speed Σωω1'_i after removal and a second integration angular speed Σωω2'_j after removal.The moment of inertia Tq for a single cylinder may be determined based on a connecting rod length L, a crankshaft radius R, an offset e, an angular speed ω of the crankshaft, a total mass m of the piston and the connecting rod, for example, as indicated in JP 2014-199 040 A, and is determined, for example, as illustrated in FIG. 6.The moment of inertia Tq can be approximated by approximating the inertial mass of the piston, the connecting rod, the crankshaft, etc. as represented by I by a motion equation of rotation of the following expression.What is to be determined in the present embodiment is an angular velocity change dω by inertia moment Tq and is determined by converting the above expression (1) to the following expression (2).Specifically, the angular velocity change amount dω by inertia torque can be determined using the inertia torque Tq generated at a certain engine speed, the inertial mass I, and the required time dt required for rotation by one unit angle at the certain engine speed, and thus becomes, for example, as illustrated in FIG. 7. Accordingly, it can be seen that in the case where the reference angular velocities in the expansion stroke and the intake stroke are the same, the relative angular velocities with respect to the compression top dead center and the exhaust top dead center are the same.In the present embodiment, since a value obtained by integrating an angular relative velocity with respect to the compression top dead center is required, it is sufficient if an integrated value of a relative value dω' with respect to a value of the compression top dead center of the angular velocity change dω is determined by inertia moment. With respect to the above-described angular velocity change amount dω', it is necessary to perform a process corresponding to that of the noise suppression technique applied to the angular velocity at each crankshaft angle. The inertia torque component at each engine speed can be determined by determining an integration value of the angular velocity change amount dω' in a unit speed and setting data to the pumping torque extractor 100, and then multiplying this value by the reference angular velocity.In the present embodiment, when the first and second integration angular velocities Σωω1'_i and Σωω2'_j are determined after the removal as described above, they are extracted as the pumping torque component in the expansion stroke and the pumping torque component in the intake stroke, respectively. FIG. 7 shows an example in which an initial torque component ( 2) is removed from an integration value ( 1) of the relative angular velocity to extract a pumping torque component ( 3).The pumping torque component depends on the engine speed and the opening of the throttle valve, and the pumping torque component when the throttle value is fully closed is, for example, as shown in FIG. 8. The extraction of the pumping torque component is determined in the form of a map, for example, by the engine speed and the intake pipe pressure using the engine speed as parameters.Since the determined pumping torque component as described above is common to vehicles of the same model, the pumping torque component is set as data to the ECU of large-scale vehicles M whose model is the same and used for correcting a misfire parameter.Referring to FIG. 1, each large-scale vehicle M includes a misfire decision device 300 and calculates a misfire parameter in running operation to decide whether or not there is a misfire. In the misfire decision device 300, a crankshaft angular velocity measurement unit 5 bdetermines an angular velocity ω.A 720-degree filter processing unit 6 bremoves an angular velocity fluctuation component resulting from load torque and friction. A relative angular velocity calculation unit 7 bcalculates first and second relative angular velocities ωω1_i and ωω2_j. An integration angular velocity calculation unit 8 bcalculates the first and second integration angular velocities Σωω1_i and Σωω2_j.A misfire parameter calculation unit 10 bcalculates a misfire parameter using the first and second integration angular speeds, the pumping torque component data set to the ECU using the standard vehicle Mref, and the first and second reference angular speeds ω 1refand ω 2ref.The integration angular velocity Σωω1_i in the expansion stroke (first integration angular velocity) and the integration angular velocity Σωω2_j in the intake stroke (second integration angular velocity) can be represented by Expressions (3) and (4) given below when the combustion torque component is represented by N; the pumping torque components in the expansion stroke and the intake stroke are represented by P1 (first pumping torque component) and P2 (second pumping torque component); the inertia torque components in the expansion stroke and the intake stroke are represented by I1 and I2; and the components by the tooth errors in the expansion stroke and the intake stroke are represented by H1 and H2.Since the inertia torque component I and the inter-tooth error H are related to the engine speed, when the inertia torque component and the inter-tooth error component at a unit speed are represented by I0and H0, respectively, the inertia torque components I1and I2may be represented by the following expressions (5) and (6), respectively.From the above expressions (3) and (5), the following expression (7) is derived, and from the expressions (4) and (6), the following expression (8) is derived.From the expressions (7) and (8), the integration angular velocity component by the combustion torque is determined in the manner given by the following expression (9).Specifically, the first pumping torque component P 1 is removed from the first integration angular velocity to determine a first integration angular velocity after removal, and the second pumping torque component P 2 is removed from the second integration angular velocity to determine a second integration angular velocity after removal. In order to correct the angular velocity difference between the strokes, the second integration angular velocity after the removal is multiplied, the ratio ω1ref / ω2refbetween the reference angular velocities, and the value N of the above expression (9) obtained by subtracting the product from the first integration angular velocity is used as the misfire parameter. A misfire decision section 11b decides whether or not there is a misfire based on the misfire parameter.According to the present embodiment, in the single cylinder engine, an inter-tooth error can be removed from a misfire parameter without measuring an inter-tooth error of the crankshaft pulse rotor in the standard vehicle, so that a misfire decision can be achieved with high accuracy.2... crankshaft, 3... crankshaft pulse rotor, 3ref... ideal crankshaft pulse rotor, 4a, 4b... crankshaft pulse sensor, 5a, 5b...Kurbelwellenwinkelgeschwindigkeitsmesseinheit 6a, 6b... 720-degree filter processing unit, 7 a, 7b...Relativwinkelgeschwindigkeitsberechnungseinheit 8 a, 8 b... Integration Angular Velocity Calculation Unit, 9 a... Inertia Moment Component Extraction Unit, 10b...Fehlzündungsparameterberechnungseinheit 11b...Fehlzündungsentscheidungsabschnitt 100... Pumping Torque Component Extraction Device, 300... Misfire Decision Device

Claims

A misfire detecting apparatus for a single cylinder engine, comprising: means (4a, 4b) for detecting an angular velocity at each crank angle from an intermediate short-wave pulse period; means (7b) for calculating a relative angular velocity at each crank angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and the vicinity of an exhaust top dead center of the engine on the basis of the angular velocity at each crank angle; means (8b) for integrating the relative angular velocity within a given crank angle range to calculate an integration angular velocity for each of an expansion stroke and an intake stroke; Misfire parameter calculating means (10b) for calculating an integration angular velocity resulting from the combustion torque from the integration angular velocity, the reference angular velocity and a specially detected pumping torque component, and determining the calculated integration angular velocity as a misfire parameter, wherein the misfire parameter calculating means includes: means for removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an expansion stroke to calculate a first integration angular velocity after the removal; means for removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an intake stroke to calculate a second integration angular velocity after the removal; and means for subtracting the second post-range integration angular velocity corrected with a relationship between the reference expansion stroke and intake stroke angular velocities from the first post-range integration angular velocity to determine a misfire parameter.The misfire detection apparatus for a single cylinder engine according to claim 1, further comprising means (6b) for removing a first angular velocity fluctuation component possibly occurring in a vehicle-mounted engine from the result of the detection of the angular velocity, wherein the relative angular velocity calculating means calculates a relative angular velocity aimed at an angular velocity from which the first angular velocity fluctuation component is removed.The misfire detection device for a single cylinder engine according to any one of claims 1 or 2, wherein the first angular velocity fluctuation component is an angular velocity fluctuation component resulting from the load torque applied from a tire or an accessory of a vehicle driven by the engine and the friction of a sliding part of the engine.A misfire detection method for a single cylinder engine, comprising: detecting an angular velocity at each crankshaft angle from an intermediate crankshaft pulse period; calculating a relative angular velocity at each crankshaft angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and in the vicinity of an exhaust top dead center of the engine based on the angular velocity at each crankshaft angle; integrating the relative angular velocity within a given crankshaft angular range to calculate an integration angular velocity for each of an expansion stroke and an intake stroke; calculating an integration angular velocity resulting from the combustion torque from the integration angular velocity, the reference angular velocity, and a specially detected pumping torque component, and determining the calculated integration angular velocity as misfire parameters, further comprising: removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an expansion stroke to calculate a first integration angular velocity after the removal; removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an intake stroke to calculate a second integration angular velocity after the removal; subtracting the second post-range integration angular velocity corrected with a relationship between the reference post-range expansion and intake-range angular velocities from the first post-range integration angular velocity to determine a misfire parameter.The misfire detection method for a single cylinder engine according to claim 4, further comprising removing a first angular velocity fluctuation component possibly occurring in a vehicle-mounted engine from a result of detecting the angular velocity, wherein a relative angular velocity aimed at an angular velocity from which the first angular velocity fluctuation component is removed is calculated.The misfire detection method for a single cylinder engine according to any one of claims 4 or 5, wherein the first angular velocity fluctuation component is an angular velocity fluctuation component resulting from the load torque applied from a tire or an accessory of a vehicle driven by the engine and the friction of a sliding part of the engine.A vehicle in which a single cylinder engine is mounted, comprising: means for detecting an angular velocity at each crank angle from an inter-crank pulse period; means for calculating a relative angular velocity at each crank angle with respect to a reference angular velocity detected in each vicinity of a compression top dead center and in the vicinity of an exhaust top dead center of the engine based on the angular velocity at each crank angle; means for integrating the relative angular velocity within a given crank angle range to calculate an integration angular velocity for each of an expansion stroke and an intake stroke; Misfire parameter calculating means for calculating an integration angular velocity resulting from the combustion torque from the integration angular velocity, the reference angular velocity and a specially detected pumping torque component, and for determining the calculated integration angular velocity as a misfire parameter, wherein the misfire parameter calculating means includes: means for removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an expansion stroke to calculate a first integration angular velocity after the removal; means for removing an integration angular velocity component resulting from the pumping torque from the integration angular velocity in an intake stroke to calculate a second integration angular velocity after the removal; and means for subtracting the second post-range integration angular velocity corrected with a relationship between the reference expansion stroke angular velocities and the intake stroke from the first post-range integration angular velocity to determine a misfire parameter.

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