Internal combustion engine system

Abstract

To operate an engine stably and quickly with a simple structure without using complicated control.SOLUTION: At a specific crank angle where the overall center of gravity of at least one balance weight is located below a rotational axis, a center of a reference part in a rotation direction of a signal rotor is arranged rearward in the rotation direction with respect to a sensed position, and is arranged within an angular range of 45 degrees from the sensed position around the rotational axis of the signal rotor.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to an internal combustion engine system.

Background Art

[0002] At the end of the crankshaft of an internal combustion engine, a signal rotor that rotates integrally with the crankshaft is provided. The signal rotor includes a plurality of teeth (protrusions) arranged at regular intervals in the circumferential direction on its outer peripheral portion, and a tooth gap (gap) having a width wider than the regular interval in the circumferential direction at a part of the outer peripheral portion of the signal rotor. A crank angle sensor disposed near the signal rotor detects the teeth of the signal rotor that rotates together with the crankshaft and outputs a pulse signal. The engine ECU grasps the crank angle based on the pulse signal and determines the ignition timing and fuel injection timing while discriminating the current stroke of the internal combustion engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When starting the engine, if the time from when the crankshaft starts to rotate by the starter motor until the first ignition occurs becomes long, the feeling at vehicle start is not good. Also, in the case of a parallel hybrid vehicle, if there is a delay in engine start, the switch from the EV driving mode to the HEV driving mode is delayed, and the feeling of changing the driving mode is not good.

[0005] Therefore, an aspect of the present disclosure aims to start the engine quickly and stably with a simple configuration without using complex control.

Means for Solving the Problems

[0006] An internal combustion engine system according to one aspect of the present disclosure includes: an internal combustion engine comprising: a horizontally extending crankshaft; and at least one balance weight connected to the crankshaft, wherein the at least one balance weight is unevenly arranged in the circumferential direction around the rotation axis of the crankshaft; a crank angle sensor; and a signal rotor that rotates in conjunction with the crankshaft, comprising: a plurality of detectable portions arranged at regular intervals in the circumferential direction on the outer circumference of the signal rotor and detectable by the crank angle sensor; and a reference portion on a part of the outer circumference of the signal rotor having a width wider in the circumferential direction than the regular interval and not detectable by the crank angle sensor. The position of the portion of the outer circumference of the signal rotor facing the crank angle sensor is the detectable position that is sensed by the crank angle sensor. In a specific crank angle where the overall center of gravity of the at least one balance weight is located below the axis of rotation, the center of the reference portion in the direction of rotation of the signal rotor is located behind the sensed position in the direction of rotation, and within a 45-degree angular range from the center of the sensed position around the axis of rotation of the signal rotor.

[0007] Another embodiment of the internal combustion engine system of the present disclosure is an internal combustion engine comprising a plurality of cylinders including a first cylinder and a second cylinder, and a crankshaft connected to the plurality of cylinders, wherein the expansion strokes are generated at unequal intervals, and the interval between adjacent ignition timings is the shortest interval between the ignition timing of the first cylinder and the ignition timing of the second cylinder; a crank angle sensor; and a signal rotor that rotates in conjunction with the crankshaft, comprising a plurality of detectable portions on the outer circumference of the signal rotor that are arranged at a constant interval in the circumferential direction and are detectable by the crank angle sensor, and a reference portion on a part of the outer circumference of the signal rotor that has a width wider in the circumferential direction than the constant interval and is not detectable by the crank angle sensor. The position of the portion of the outer circumference of the signal rotor that faces the crank angle sensor is the detectable position that is sensed by the crank angle sensor. The center of the reference portion in the rotational direction of the signal rotor is positioned in front of the ignition timing portion at the sensing position of the ignition timing of the first cylinder in the rotational direction, and is positioned within a 45-degree angular range from the center of the ignition timing portion around the rotational axis. [Effects of the Invention]

[0008] According to this disclosure, the engine can be started quickly and stably. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram of an internal combustion engine system according to the first embodiment. [Figure 2] Figure 2 is a magnified view of the signal rotor and crank angle sensor shown in Figure 1. [Figure 3] Figure 3 is a transition diagram showing the correspondence between the stroke of the internal combustion engine (single cylinder) in Figure 1 and the signal rotor. [Figure 4] Figure 4 shows another example of the arrangement of the reference section in the signal rotor shown in Figure 3. [Figure 5]Figure 5 is a schematic diagram of an internal combustion engine (two cylinders with a 360-degree crank) according to the second embodiment. [Figure 6A] Figure 6A is a transition diagram showing the relationship between the stroke and the signal rotor of the internal combustion engine (two cylinders with a 360-degree crank) shown in Figure 5. [Figure 6B] Figure 6B is a schematic diagram showing a continuation of Figure 6A. [Figure 7A] Figure 7A is a transition diagram showing the correspondence between the stroke and the signal rotor of an internal combustion engine (uneven-interval combustion engine) according to the second embodiment. [Figure 7B] Figure 7B is a schematic diagram showing a continuation of Figure 7A. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings.

[0011] (First Embodiment) Figure 1 is a block diagram of an internal combustion engine system 1 according to the first embodiment. As shown in Figure 1, the internal combustion engine system 1 comprises an internal combustion engine 2, a crank angle sensor 3, a signal rotor 4, an electric motor 5, and a controller 6. The internal combustion engine system 1 is mounted as a driving source in vehicles such as motorcycles, three-wheeled vehicles, and off-road four-wheeled vehicles.

[0012] The internal combustion engine 2 is, for example, a single-cylinder engine. The internal combustion engine 2 has a cylinder 10. A piston 11 is reciprocally housed in the cylinder 10. The piston 11 is connected to a crankshaft 15 via a connecting rod 12, a crankpin 13, and a crank arm 14. The crankshaft 15 extends horizontally. A balance weight 16 is connected to the crankshaft 15. The balance weight 16 is unevenly distributed in the circumferential direction around the rotation axis X of the crankshaft 15. The overall center of gravity G of the balance weight 16 is offset from the rotation axis X.

[0013] The internal combustion engine 2 is, for example, a four-stroke engine. A combustion chamber 17 is defined in the cylinder 10 above the piston 11. The internal combustion engine 2 has an intake port 18 communicating with the combustion chamber 17 and an exhaust port 19 communicating with the combustion chamber 17. An intake valve 20 is located in the intake port 18, and an exhaust valve 21 is located in the exhaust port 19. The intake port 18 is provided with a fuel injector 22 for injecting fuel into its intake passage. The intake port 18 is also provided with an intake pressure sensor 23 for detecting the pressure of the intake air flowing through its intake passage. The internal combustion engine 2 is provided with a spark plug 24 for igniting the fuel-air mixture in the combustion chamber 17.

[0014] A signal rotor 4 is fixed to the end of the crankshaft 15. The crank angle sensor 3 faces the signal rotor 4 from a direction perpendicular to the rotation axis X. Details of the crank angle sensor 3 and signal rotor 4 will be described later. The electric motor 5 is mechanically connected to the crankshaft 15 so that it can drive the crankshaft 15. The drive shaft of the electric motor 5 is connected to the crankshaft 15 via a gear mechanism, a belt-pulley mechanism, or a chain-sprocket mechanism.

[0015] The controller 6 controls the internal combustion engine 2 and the electric motor 5. The controller 6 includes a processor 31, system memory 32, and storage memory 33. The processor 31 is, for example, a central processing unit. The system memory 32 is, for example, RAM. The storage memory 33 is an example of a computer-readable medium, and is a non-temporary, tangible medium. The storage memory 33 may include ROM. The storage memory 33 may include a hard disk, flash memory, or a combination thereof. The storage memory 33 stores programs. An example of a processing circuit is one in which the processor 31 executes a program read from the system memory 32.

[0016] The controller 6 determines the stroke (intake, compression, expansion, exhaust) during the operation of the internal combustion engine 2 based on the crank angle detected by the crank angle sensor 3 and the intake pressure detected by the intake pressure sensor 23. The intake pressure is an example of a physical quantity that changes depending on the state of the combustion chamber 17 for each stroke. The controller 6 controls the operation timing of the fuel injector 22 and the ignition plug 24 based on the determined stroke.

[0017] FIG. 2 is an enlarged view of the signal rotor 4 and the crank angle sensor 3 in FIG. 1. As shown in FIG. 2, the signal rotor 4 is fixed to the crankshaft 15 so as to rotate integrally with the crankshaft 15 around the rotation axis X of the crankshaft 15. The outer peripheral portion of the signal rotor 4 includes a plurality of detected portions 4a arranged at regular intervals in the circumferential direction C thereof, and a reference portion 4b having a width wider than the regular interval in the circumferential direction C. The detected portion 4a is a portion detected by the detection portion 3a of the crank angle sensor 3. The reference portion 4b has a width wider than the regular interval in the circumferential direction C. The reference portion 4b is a portion not detected by the crank angle sensor 3.

[0018] For example, the crank angle sensor 3 is an electromagnetic pickup sensor, and the signal rotor 4 is made of metal. The detected portion 4a is a protrusion (tooth) protruding radially outward from the outer peripheral portion of the signal rotor 4. The gap 4c between two adjacent detected portions 4a is a portion not detected by the detection portion 3a of the crank angle sensor 3. The width of the reference portion 4b in the circumferential direction C is larger than the width of the gap 4c in the circumferential direction C. Specifically, the reference portion 4b is a wide gap (missing tooth) formed by omitting one of a plurality of protrusions arranged at equal intervals in the circumferential direction C over the entire circumference of the outer peripheral portion of the signal rotor 4.

[0019] The position of the part of the outer circumference of the signal rotor 4 that faces the detection part 3a of the crank angle sensor 3 is the detected position P that is sensed by the crank angle sensor 3. Because the width of the circumferential direction C of the gap 4c and the width of the circumferential direction C of the reference part 4b are different, the controller 6 can recognize the reference part 4b separately from the gap 4c based on the detection signal of the crank angle sensor 3. The controller 6 detects the base angle of the crank angle by recognizing that the reference part 4b is at the detected position P. The controller 6 calculates the angular displacement from the base angle by counting the detected part 4a that is detected after the detection of the reference part 4b.

[0020] Figure 3 is a transition diagram showing the correspondence between the strokes of the internal combustion engine 2 (single cylinder) in Figure 1 and the signal rotor 4. As shown in Figure 3, the internal combustion engine 2 repeats a cycle consisting of exhaust, intake, compression, and expansion strokes. In the example in Figure 3, the posture of the balance weight 16 in the crank angle range from "(1) exhaust" to "(8) intake" is the same as the posture of the balance weight 16 in the crank angle range from "(9) compression" to "(16) expansion". In particular, the crank angle range from "(3) exhaust" to "(5) intake" and the crank angle range from "(11) compression" to "(13) expansion" are ranges in which the center of gravity G of the balance weight 16 is located below the rotation axis X of the crankshaft 15. This crank angle range will be called the specific crank angle range, and one crank angle within that specific crank angle range will be called the specific crank angle.

[0021] In at least one specific crank angle within the specified crank angle range, the center of the reference portion 4b of the signal rotor 4 in the direction of rotation is positioned behind the sensed position P in the direction of rotation, and within a 45-degree angular range from the center of the sensed position P in the circumferential direction C around the rotation axis X. Here, "behind the sensed position P in the direction of rotation" means an angular region within a 180-degree range in the opposite direction of rotation of the signal rotor 4 with respect to the center of the sensed position P. In the example in Figure 3, throughout the entire specified crank angle range, the center of the reference portion 4b of the signal rotor 4 in the direction of rotation is positioned behind the sensed position P in the direction of rotation.

[0022] The portion of the outer circumference of the signal rotor 4 that is at the sensing position P during the ignition timing at the start of the internal combustion engine 2 is referred to as the ignition timing portion 4d. The reference portion 4b of the signal rotor 4 is located in a different part of the outer circumference of the signal rotor 4 from the ignition timing portion 4d. If the ignition timing changes depending on the operating conditions of the internal combustion engine 2, it is preferable that the reference portion 4b of the signal rotor 4 is located in a different part of the outer circumference of the signal rotor 4 from the portions that are at the sensing position P for each possible ignition timing.

[0023] Because the balance weights 16 are unevenly distributed in the circumferential direction C around the rotation axis X, there is a high probability that the internal combustion engine 2 will stop when the overall center of gravity G of the balance weights 16 is located below the rotation axis X (each state enclosed by the dashed line in Figure 3). In this embodiment, since the reference portion 4b of the signal rotor 4 is positioned as described above, the reference portion 4b of the signal rotor 4 is quickly detected by the crank angle sensor 3 when the internal combustion engine 2 is started. Therefore, when the internal combustion engine 2 is started, the controller 6 can quickly grasp the current crank angle and start the internal combustion engine 2 quickly and stably.

[0024] The controller 6 may control the electric motor 5 so that the crank angle of the internal combustion engine 2 becomes the specified crank angle when the operating internal combustion engine 2 stops. That is, the controller 6 may control the electric motor 5 so that when the internal combustion engine 2 stops, the center of the reference portion 4b of the signal rotor 4 in the direction of rotation is positioned behind the sensing position P in the direction of rotation and within a 45-degree angular range from the center of the sensing position P. This further increases the possibility that the reference portion 4b of the signal rotor 4 will be quickly detected by the crank angle sensor 3 when the internal combustion engine 2 starts.

[0025] Furthermore, since the arrangement of the reference portion 4b of the signal rotor 4 is determined by referring to the orientation of the balance weight 16 regardless of the orientation of the cylinder 10, the cylinder 10 does not have to be arranged extending vertically. For example, the cylinder 10 may extend diagonally with respect to the vertical direction, or it may extend horizontally.

[0026] Figure 4 shows another example of the arrangement of the reference portion 4b in the signal rotor 4 of Figure 3. In the example of Figure 4, ignition occurs when "(12) compression". At the ignition crank angle corresponding to the ignition timing when the internal combustion engine 2 is started, the center of the reference portion 4b in the rotational direction of the signal rotor 4 is positioned in front of the sensed position P in the rotational direction. Here, "in front of the sensed position P in the rotational direction" means an angular range within 180 degrees in the rotational direction of the signal rotor 4, i.e., the forward rotational direction, with respect to the sensed position P. Furthermore, at the ignition crank angle, the center of the reference portion 4b in the rotational direction of the signal rotor 4 is positioned within an angular range of 45 degrees from the center of the sensed position P in the circumferential direction C around the rotation axis X.

[0027] With this configuration, the ignition timing arrives quickly after the crank angle sensor 3 detects the reference portion 4b of the signal rotor 4. Therefore, the ignition timing arrives in a short time when starting the internal combustion engine 2, allowing the internal combustion engine 2 to start quickly.

[0028] In the example shown in Figure 4, at least one specific crank angle within the specified crank angle range (for example, "(3) Exhaust" and "(11) Compression"), the center of the reference portion 4b of the signal rotor 4 in the direction of rotation is positioned behind the sensed position P in the direction of rotation, and within a 45-degree angular range from the center of the sensed position P.

[0029] Furthermore, since the arrangement of the reference portion 4b of the signal rotor 4 is determined by referring to the orientation of the balance weights 16 which are unevenly arranged around the rotation axis X, the number of cylinders is not limited to 1 or 2. As long as the balance weights 16 as a whole are unevenly arranged around the rotation axis X, the number of cylinders may be 3 or more.

[0030] (Second Embodiment) Figure 5 is a schematic diagram of an internal combustion engine 102 (two-cylinder with a 360-degree crank) according to the second embodiment. Components common to the first embodiment are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 5, the internal combustion engine 102 is a two-cylinder engine with a 360-degree crank. That is, the arrangement angle of the crankpin 13 around the crankshaft 15 in the first cylinder 10A and the arrangement angle of the crankpin 13 around the crankshaft 15 in the second cylinder 10B are the same. The first cylinder 10A and the second cylinder 10B may perform strokes with a 360-degree difference in crank angle, or they may perform the same stroke simultaneously.

[0031] Figure 6A is a transition diagram showing the correspondence between the strokes of the internal combustion engine 102 (two-cylinder engine with a 360-degree crank) in Figure 5 and the signal rotor 4. Figure 6B is a schematic diagram showing a continuation of Figure 6A. As shown in Figures 6A and B, the basic concept is the same for the two-cylinder engine 102 with a 360-degree crank as for the single-cylinder engine 2. The first cylinder 10A and the second cylinder 10B perform their strokes with a 360-degree difference in crank angle. In the example in Figures 6A and B, the crank angle range from "(1) exhaust" to "(12) expansion" of the first cylinder 10A and the crank angle range from "(1) compression" to "(12) intake" of the second cylinder 10B are the same.

[0032] In the first crank angle range, which is the range from "(2) exhaust" to "(4) intake" of the first cylinder 10A and the range from "(2) compression" to "(4) expansion" of the second cylinder 10B, and in the second crank angle range, which is the range from "(8) compression" to "(10) expansion" of the first cylinder 10A and the range from "(8) exhaust" to "(10) intake" of the second cylinder 10B, the overall center of gravity G of the balance weight 16 is located below the rotation axis X of the crankshaft 15. The first crank angle range and the second crank angle range are referred to as specific crank angle ranges, and one crank angle in the specific crank angle range is referred to as a specific crank angle.

[0033] In at least one specific crank angle within the specified crank angle range, the center of the reference portion 4b of the signal rotor 4 in the direction of rotation is located behind the sensed position P in the direction of rotation, and within a 45-degree angular range from the center of the sensed position P in the circumferential direction C around the rotation axis X. In the examples of Figures 6A and 6B, throughout the entire specified crank angle range, the center of the reference portion 4b of the signal rotor 4 in the direction of rotation is located behind the center of the sensed position P in the direction of rotation.

[0034] Since the balance weights 16 are unevenly distributed in the circumferential direction C around the rotation axis X, there is a high probability that the internal combustion engine 102 will stop when the overall center of gravity G of the balance weights 16 is located below the rotation axis X (each state enclosed by the dashed lines in Figures 6A and 6B). In this embodiment, since the reference portion 4b of the signal rotor 4 is positioned as described above, the reference portion 4b of the signal rotor 4 is quickly detected by the crank angle sensor 3 when the internal combustion engine 102 is started. Therefore, when the internal combustion engine 102 is started, the controller 6 can quickly grasp the current crank angle and start the internal combustion engine 2 quickly and stably. Note that the other configurations are the same as in the first embodiment described above, so their explanation is omitted.

[0035] (Third embodiment) Figure 7A is a transition diagram showing the correspondence between the strokes of the internal combustion engine 202 (uneven-interval combustion engine) according to the third embodiment and the signal rotor 4. Figure 7B is a schematic diagram showing a continuation of Figure 7A. Components common to the first embodiment are denoted by the same reference numerals and their explanations are omitted. As shown in Figures 7A and 7B, the internal combustion engine 202 is an uneven-interval combustion engine. That is, the internal combustion engine 202 generates expansion strokes (explosion strokes) at uneven intervals throughout the entirety of the first cylinder 10C and the second cylinder 10D. In this embodiment, the interval from the ignition timing of the first cylinder 10C to the ignition timing of the second cylinder 10D is the shortest interval among adjacent ignition timing intervals. That is, the interval from the ignition timing of the first cylinder 10C to the ignition timing of the second cylinder 10D is smaller than the interval from the ignition timing of the second cylinder 10D to the ignition timing of the first cylinder 10C.

[0036] The center of the reference portion 4b of the signal rotor 4 in the direction of rotation is positioned ahead of the ignition timing portion 4d at engine start-up, and within a 45-degree angular range from the ignition timing portion 4d around the rotation axis X of the signal rotor 4. Here, "ahead of the ignition timing portion 4d in the direction of rotation" means an angular range within 180 degrees in the direction of rotation of the signal rotor 4, i.e., the forward direction of rotation, with reference to the center of the ignition timing portion 4d.

[0037] As a result, the ignition timing for the first cylinder 10C arrives shortly after the crank angle sensor 3 detects the reference portion 4b of the signal rotor 4, followed shortly after by the ignition timing for the second cylinder 10D. Therefore, the internal combustion engine 202 can be started quickly and stably. The other configurations are the same as those of the first embodiment described above, so their explanation is omitted.

[0038] As described above, the embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments to create new embodiments. For example, some components or methods in one embodiment may be applied to other embodiments, and some components in an embodiment can be separated from other components in that embodiment and extracted as appropriate. In addition, the components described in the attached drawings and detailed description include not only components that are essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology.

[0039] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0040] Each of the following items is a disclosure of a preferred embodiment.

[0041] [Item 1] An internal combustion engine comprising a horizontally extending crankshaft and at least one balance weight connected to the crankshaft, wherein the at least one balance weight is unevenly distributed in the circumferential direction around the rotation axis of the crankshaft, Crank angle sensor and A signal rotor that rotates in conjunction with the crankshaft, comprising: a plurality of detectable portions arranged at regular intervals in the circumferential direction on the outer circumference of the signal rotor and detectable by the crank angle sensor; and a reference portion on a part of the outer circumference of the signal rotor that has a width wider in the circumferential direction than the regular interval and is not detectable by the crank angle sensor, The position of the portion of the outer circumference of the signal rotor that faces the crank angle sensor is the position to be detected by the crank angle sensor. An internal combustion engine system in which, at a specific crank angle where the overall center of gravity of at least one balance weight is located below the axis of rotation, the center of the reference portion in the direction of rotation of the signal rotor is located behind the sensed position in the direction of rotation, and is located within a 45-degree angular range from the center of the sensed position around the axis of rotation of the signal rotor.

[0042] In this configuration, at least one balance weight is unevenly distributed in the circumferential direction around the axis of rotation, making it highly likely that the internal combustion engine will stall at a specific crank angle where the overall center of gravity of the balance weights is below the axis of rotation. Furthermore, the rotational center of the reference part of the signal rotor is positioned behind the sensing position in the direction of rotation at a specific crank angle, and within a 45-degree angular range from the sensing position around the axis of rotation. Therefore, when the engine starts, the reference part of the signal rotor is quickly detected by the crank angle sensor. Thus, the current crank angle can be quickly determined when starting the engine, allowing for a rapid and stable engine start.

[0043] [Item 2] The internal combustion engine system according to item 1, wherein, at the ignition crank angle corresponding to the ignition timing at startup of the internal combustion engine, the center of the reference portion of the signal rotor in the direction of rotation is positioned in front of the sensing position in the direction of rotation, and is positioned within a 45-degree angular range around the rotation axis from the center of the sensing position.

[0044] With this configuration, the ignition timing arrives quickly after the crank angle sensor detects the reference point of the signal rotor. Therefore, the ignition timing arrives in a short time during engine startup, allowing the engine to start quickly.

[0045] [Item 3] The internal combustion engine system described in item 1 or 2, wherein the internal combustion engine is a single-cylinder engine or a two-cylinder engine with a 360-degree crank.

[0046] This configuration allows for rapid engine starting in an engine where at least one balance weight is unevenly distributed in the circumferential direction around the axis of rotation, through proper placement of the reference portion of the signal rotor.

[0047] [Item 4] An electric motor that can be connected to the aforementioned crankshaft, The system further comprises a processing circuit for controlling the internal combustion engine and the electric motor, The internal combustion engine system according to any one of items 1 to 3, wherein the processing circuit controls the electric motor so that the crank angle of the internal combustion engine becomes the specific crank angle when the internal combustion engine stops.

[0048] This configuration further increases the likelihood that the crank angle sensor will quickly detect the reference point of the signal rotor when the engine starts.

[0049] [Item 5] An internal combustion engine comprising a plurality of cylinders including a first cylinder and a second cylinder, and a crankshaft connected to the plurality of cylinders, wherein the expansion strokes are generated at unequal intervals, and the interval between adjacent ignition timings is the shortest interval between the ignition timing of the first cylinder and the ignition timing of the second cylinder, Crank angle sensor and A signal rotor that rotates in conjunction with the crankshaft, comprising: a plurality of detectable portions arranged at regular intervals in the circumferential direction on the outer circumference of the signal rotor and detectable by the crank angle sensor; and a reference portion on a part of the outer circumference of the signal rotor that has a width wider in the circumferential direction than the regular interval and is not detectable by the crank angle sensor, The position of the portion of the outer circumference of the signal rotor that faces the crank angle sensor is the position to be detected by the crank angle sensor. An internal combustion engine system wherein the center of the reference portion of the signal rotor in the direction of rotation is positioned in front of the ignition timing portion at the sensing position of the ignition timing of the first cylinder in the direction of rotation, and is positioned within a 45-degree angular range from the center of the ignition timing portion around the rotation axis of the signal rotor.

[0050] With this configuration, the ignition timing for the first cylinder arrives shortly after the crank angle sensor detects the reference point of the signal rotor, followed shortly after by the ignition timing for the second cylinder. Therefore, the engine can be started quickly and stably. [Explanation of Symbols]

[0051] 1. Internal combustion engine system 2,102,202 Internal combustion engines 3. Crank angle sensor 4 signal rotors 4a Detected part 4b Reference section 4d ignition timing part 5 Electric motor 6 Controllers 10 cylinders 10C First Cylinder 10D 2nd Cylinder 15 Crank Axle 16 Balance weights G center of gravity P Sensed position X rotation axis

Claims

1. An internal combustion engine comprising a horizontally extending crankshaft and at least one balance weight connected to the crankshaft, wherein the overall center of gravity of the at least one balance weight is located offset from the rotation axis of the crankshaft, Crank angle sensor and A signal rotor that rotates in conjunction with the crankshaft, comprising: a plurality of detectable portions arranged at regular intervals in the circumferential direction around the rotation axis on the outer circumference of the signal rotor and detectable by the crank angle sensor; and a reference portion on a part of the outer circumference of the signal rotor that has a width wider in the circumferential direction than the regular interval and is not detectable by the crank angle sensor, The position of the portion of the outer circumference of the signal rotor that faces the crank angle sensor is the position to be detected by the crank angle sensor. An internal combustion engine system in which, at a specific crank angle in which the overall center of gravity of at least one balance weight is located below the axis of rotation, the center of the reference portion in the direction of rotation of the signal rotor is located behind the sensed position in the direction of rotation, and is located within a 45-degree angular range from the center of the sensed position around the axis of rotation.

2. The internal combustion engine system according to claim 1, wherein, in the ignition crank angle corresponding to the ignition timing at startup of the internal combustion engine, the center of the reference portion of the signal rotor in the direction of rotation is positioned in front of the sensing position in the direction of rotation, and is positioned within a 45-degree angular range around the rotation axis from the center of the sensing position.

3. The internal combustion engine system according to claim 1 or 2, wherein the internal combustion engine is a single-cylinder engine or a two-cylinder engine with a 360-degree crank.

4. An electric motor that can be connected to the aforementioned crankshaft, The system further comprises a processing circuit for controlling the internal combustion engine and the electric motor, The internal combustion engine system according to claim 1 or 2, wherein the processing circuit controls the electric motor so that the crank angle of the internal combustion engine becomes the specific crank angle when the internal combustion engine stops.

5. An internal combustion engine comprising a plurality of cylinders including a first cylinder and a second cylinder, and a crankshaft connected to the plurality of cylinders, wherein the expansion strokes are generated at unequal intervals, and the interval between adjacent ignition timings is the shortest interval between the ignition timing of the first cylinder and the ignition timing of the second cylinder, Crank angle sensor and A signal rotor that rotates in conjunction with the crankshaft, comprising: a plurality of detectable portions arranged at regular intervals in the circumferential direction on the outer circumference of the signal rotor and detectable by the crank angle sensor; and a reference portion on a part of the outer circumference of the signal rotor that has a width wider in the circumferential direction than the regular interval and is not detectable by the crank angle sensor, The position of the portion of the outer circumference of the signal rotor that faces the crank angle sensor is the position to be detected by the crank angle sensor. An internal combustion engine system in which the center of the reference portion of the signal rotor in the direction of rotation is positioned in front of the ignition timing portion at the sensing position of the ignition timing of the first cylinder in the direction of rotation of the outer circumference, and is positioned within a 45-degree angular range from the center of the ignition timing portion around the rotation axis of the signal rotor.

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