Rotation speed control device

Abstract

This suppresses the abrupt drop in engine speed when transitioning to a partial cylinder deactivation state during engine idling. [Solution] The engine deactivates some of its cylinders during idle operation. The engine's rotational speed control device is provided with a first integral controller (41) that sets the target throttle opening for all cylinders based on the integral value of the deviation between the target idle speed and the engine speed when all cylinders are operating during idle operation, and a second integral controller (51) that sets the target throttle opening for the operating cylinders based on the integral value of the deviation between the target idle speed and the engine speed when some cylinders are deactivated during idle operation. When transitioning to the partial cylinder deactivation state, the integral value of the second integral controller is reset to a value corresponding to the target idle speed.

Description

Technical Field

[0001] The present invention relates to an engine speed control device.

Background Art

[0002] Conventionally, as an engine, an engine in which combustion can be stopped in some of a plurality of cylinders has been proposed (see, for example, Patent Document 1). In the engine described in Patent Document 1, the number of operating cylinders is controlled according to the operating conditions, the operation of some cylinders is stopped, and the fuel consumption of the engine is improved. In this case, the operation of the cylinder is stopped by cutting off fuel injection and ignition to the cylinder. Therefore, the intake valve and the exhaust valve are always driven in all cylinders including the stopped cylinders, and a valve stop mechanism for the engine becomes unnecessary and the configuration of the valve mechanism does not become complicated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the engine described in Patent Document 1, since there is no valve stop mechanism, various losses including pump loss do not decrease in a partial cylinder stop state during idling operation. Immediately after the cylinder is stopped, the engine speed drops rapidly, and there is a risk that the feedback of the engine speed to the target idle speed will not be in time and the engine will stall, or vibrations and the like will occur due to a temporary drop in the engine speed, giving the driver an uncomfortable feeling.

[0005] The present invention has been made in view of such points, and an object thereof is to provide a speed control device capable of suppressing a rapid decrease in the engine speed when shifting to a partial cylinder stop state during the idle operation of the engine. [Means for solving the problem]

[0006] A rotational speed control device according to one aspect of the present invention is a rotational speed control device for an engine that deactivates the operation of some cylinders during idle operation, comprising: a first integral controller that sets the target throttle opening for all cylinders based on the integral value of the deviation between the target idle speed and the engine speed when all cylinders are operating during idle operation; and a second integral controller that sets the target throttle opening for the operating cylinders based on the integral value of the deviation between the target idle speed and the engine speed when some cylinders are deactivated during idle operation, thereby solving the above problem by resetting the integral value of the second integral controller to a value corresponding to the target idle speed when transitioning to the partial cylinder deactivation state. [Effects of the Invention]

[0007] According to one embodiment of the present invention, when transitioning to a partial cylinder deactivation state during idle operation, the target throttle opening for the operating cylinders changes immediately without waiting for feedback on the engine speed after cylinder deactivation, thereby suppressing a rapid drop in engine speed. As a result, feedback on the engine speed relative to the target idle speed is received in time, preventing engine stalling, and reducing vibrations and other issues caused by a temporary drop in engine speed, thereby reducing driver discomfort during partial cylinder deactivation. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of the engine in this embodiment. [Figure 2] This is a control block diagram of the engine speed control device for the comparative example. [Figure 3] This is a control block diagram of the engine speed control device in this embodiment. [Figure 4] This is a control block diagram of the idle speed controller in this embodiment. [Figure 5] This is a circuit diagram of the target throttle opening switching circuit in this embodiment. [Figure 6]This figure shows the timing for switching the target throttle opening in this embodiment. [Modes for carrying out the invention]

[0009] An engine according to one aspect of the present invention deactivates some cylinders during idle operation. The engine speed control device of this engine is equipped with first and second integral controllers. In the first integral controller, the target throttle opening for all cylinders is set based on the integral value of the deviation between the target idle speed and the engine speed when all cylinders are operating during idle operation. In the second integral controller, the target throttle opening for the operating cylinders is set based on the integral value of the deviation between the target idle speed and the engine speed when some cylinders are deactivated during idle operation. When transitioning to the partial cylinder deactivation state, the integral value of the second integral controller is reset to a value corresponding to the target idle speed. As a result, when transitioning to partial cylinder deactivation during idle operation, the target throttle opening for the operating cylinders changes immediately without waiting for feedback on the engine speed after cylinder deactivation, suppressing a rapid drop in engine speed. The feedback on the engine speed relative to the target idle speed is received in time, preventing engine stalling, and vibrations caused by a temporary drop in engine speed are suppressed, reducing driver discomfort in the partial cylinder deactivation state. [Examples]

[0010] The engine of the saddle-type vehicle equipped with the rotational speed control device of this embodiment will be described below with reference to the attached drawings. Figure 1 is a side view of the engine of this embodiment. In the following figures, arrow Fr indicates the front of the vehicle, and arrow Re indicates the rear of the vehicle.

[0011] As shown in Figure 1, engine 1 is a V-type twin-cylinder engine with front and rear cylinder assemblies arranged in a V-shape on a crankcase 2. The first cylinder (front cylinder) 10 is mounted in a forward-leaning position on the front upper surface of the crankcase 2, and the second cylinder (rear cylinder) 20 is mounted in a rearward-leaning position on the rear upper surface of the crankcase 2. The first cylinder 10 and the second cylinder 20 are mounted at a bank angle of 90° around the crankshaft. Although not shown in detail, the first cylinder 10 is located at the front of the saddle-type vehicle, and the second cylinder 20 is located in the center of the saddle-type vehicle.

[0012] A first exhaust pipe (not shown) is connected to the front of the first cylinder 10, and a first intake pipe 11 is connected to the rear of the first cylinder 10. A second intake pipe 21 is connected to the front of the second cylinder 20, and a second exhaust pipe (not shown) is connected to the rear of the second cylinder 20. The first and second intake pipes 11 and 21 extend upward, and a first throttle body 12 is provided in the first intake pipe 11, and a second throttle body 22 is provided in the second intake pipe 21. A first injector 13 is provided in the first throttle body 12, and a second injector 23 is provided in the second throttle body 22.

[0013] The first throttle body 12 is equipped with a first throttle valve 14, and the second throttle body 22 is equipped with a second throttle valve 24. The first and second throttle valves 14 and 24 are electronically controlled throttle valves, and each throttle valve 14 and 24 is driven to open and close by a motor. Because the first and second throttle valves 14 and 24 each have their own motors, the first and second throttle valves 14 and 24 are individually controlled, and the intake volume is adjusted for each cylinder. In addition, the first and second injectors 13 and 23 and the first and second throttle valves 14 and 24 are controlled by an ECU (not shown).

[0014] Incidentally, as shown in the comparative example in Figure 2, the engine speed during idle operation is controlled by the engine speed control device 71 of the engine 70. The engine speed control device 71 is equipped with an idle speed controller 72 and first and second throttle opening controllers 73 and 74. During idle operation, the engine speed is fed back from the engine 70 to the idle speed controller 72, and the throttle openings of the first and second cylinders 10 and 20 are controlled by the first and second throttle opening controllers 73 and 74 according to the target throttle opening and synchronization adjustment opening from the idle speed controller 72. The amount of intake air to each cylinder of the engine 70 is adjusted and the engine speed is maintained at a predetermined value.

[0015] Furthermore, the engine 70 can improve fuel efficiency by deactivating some cylinders during idle operation. Proposed cylinder deactivation control configurations include cutting fuel injection to deactivated cylinders to deactivate some cylinders, and a configuration that cuts fuel injection to deactivated cylinders and also stops the valve movement of the intake and exhaust valves. Cutting fuel injection alone increases pumping losses because the intake and exhaust valves are operated not only in the active cylinders but also in the deactivated cylinders. Pumping losses can be reduced by stopping the valve movement of the intake and exhaust valves, but this requires a valve movement stopping mechanism in the engine 70, making the device configuration more complex.

[0016] If the engine 70 is not equipped with a valve train deactivation mechanism, pump losses increase during cylinder deactivation while idling, causing a sharp drop in engine speed immediately after cylinder deactivation. With the feedback control described above, it takes a long time for the engine speed to stabilize. Alternatively, the rapid drop in engine speed may cause the engine to stall because the feedback of engine speed relative to the target idle speed cannot keep up. Even without stalling, the temporary drop in engine speed can cause vibrations and noises, or the tachometer needle may move erratically, causing discomfort to the driver.

[0017] The engine 1 of this embodiment is not provided with a valve stop mechanism either. Therefore, in the idle speed controller of this embodiment, the main integral controller and the sub-integral controller for setting the target throttle opening degree of the operating cylinders are selectively used according to the presence or absence of cylinder stoppage during idle operation. When shifting to a partial cylinder stoppage state, the main integral controller is switched to the sub-integral controller, and the integral value of the sub-integral controller is reset to a value corresponding to the target throttle opening degree. By resetting the integral value, the target throttle opening degree of the operating cylinders is immediately set without waiting for the feedback of the engine speed, and a rapid decrease in the engine speed is suppressed.

[0018] Hereinafter, referring to FIGS. 3 and 4, the engine speed control device of this embodiment will be described. FIG. 3 is a control block diagram of the engine speed control device of this embodiment. FIG. 4 is a control block diagram of the idle speed controller of this embodiment.

[0019] As shown in FIG. 3, in the subtraction element 31 of the engine speed control device 30, the target idle speed and the engine speed fed back from the engine 1 are subtracted to calculate the speed deviation. In the idle speed controller 32, the target throttle opening degrees of the first and second cylinders 10 and 20 are set based on the speed deviation. In the first throttle opening degree controller 33, the throttle opening degree of the first cylinder 10 is controlled based on the target throttle opening degree, and in the second throttle opening degree controller 34, the throttle opening degree of the second cylinder 20 is controlled based on the target throttle opening degree. The intake air amounts to the first and second cylinders 10 and 20 are adjusted to control the engine speed during the idle operation of the engine 1.

[0020] Incidentally, although details will be described later, in the idle speed controller 32, the target throttle opening degrees for normal (all-cylinder operation state) and for cylinder suspension are set for the first and second cylinders 10 and 20. Further, a switching circuit 60 is provided in the rotational speed control device 30, and the normal target throttle opening degrees and the target throttle opening degrees for cylinder suspension of the first and second cylinders 10 and 20 are switched by the switching circuit 60. The switching timing of the normal target throttle opening degree and the target throttle opening degree for cylinder suspension will be described later. Also, a determination device (not shown) such as the establishment condition of cylinder suspension is provided in the rotational speed control device 30.

[0021] In the all-cylinder operation state during idle operation, the first and second cylinders 10 and 20 are the operating cylinders, and in the partial cylinder suspension state during idle operation, the second cylinder 20 is switched to the suspended cylinder and the fuel consumption is improved by fuel cut. The second cylinder 20 is the rear cylinder positioned at the center in the vehicle front-rear direction where heat is likely to accumulate, and by suspending the operation of the second cylinder 20, the heat generation during the implementation of cylinder suspension is suppressed and the heat damage to peripheral components is reduced. The fuel is port-injected, and even when fuel cut is performed, the unburned gas adhering to the port is discharged. By fixing the suspended cylinder to the second cylinder 20, the discharge amount of unburned gas from the engine 1 is suppressed.

[0022] As shown in FIG. 4, in the all-cylinder operation state during idle operation, the first - fourth switches 42, 47, 49, 55 are in the broken line state and the first integral controller 41 is effective. In the first adding element 43 of the first integral controller 41, the rotational speed deviation input from the first switch 42 and the accumulated deviation delayed by one cycle (the accumulated deviation up to the previous cycle) input from the first delay element 44 are added, and the current accumulated deviation is calculated as the integral value. In the first arithmetic element 45 of the first integral controller 41, the integral value is multiplied by a certain magnification, and in the second adding element 46, various corrections are applied to the output result of the first arithmetic element 45 to calculate the target throttle opening degree for the first cylinder 10.

[0023] The target throttle opening for the first cylinder is output from the first integral controller 41 to the first throttle opening controller 33 via the second switch 47. In addition, the third additive element 48 adds the synchronization adjustment opening to the target throttle opening for the first cylinder 10 to calculate the target throttle opening for the second cylinder 20. The target throttle opening for the second cylinder 20 is output to the second throttle opening controller 34 via the third switch 49. In this way, the first integral controller 41 sets the target throttle opening for all cylinders based on the integral value of the difference between the target idle speed and the engine speed when all cylinders are operating during idle operation.

[0024] During idle operation, when some cylinders are deactivated, the first to fourth switches 42, 47, 49, and 55 are in a solid state, indicating that the second integral controller 51 is active. In the fourth additive element 52 of the second integral controller 51, the cumulative deviation (cumulative deviation up to the previous cycle) input from the second delay element 53, which is delayed by one cycle, is added to the rotational speed deviation, and the current cumulative deviation is calculated as an integral value. In the second calculation element 54 of the second integral controller 51, a constant multiplier is applied to the integral value to calculate the target throttle opening for the first cylinder 10. The target throttle opening for the first cylinder 10 is output to the first throttle opening controller 33 via the second switch 47.

[0025] Thus, in the second integral controller 51, the target throttle opening of the first cylinder (operating cylinder) 10 is set based on the integral value of the deviation between the target idle speed and the engine speed during partial cylinder deactivation while idling. At this time, when transitioning to the partial cylinder deactivation state, the integral value of the second integral controller 51 is reset to a value corresponding to the target idle speed of the first cylinder 10, and the shaft output of the engine 1 is quickly set without waiting for engine speed feedback. More specifically, the integral value of the second integral controller 51 is reset to a value corresponding to the coolant temperature of the engine 1.

[0026] The mechanical losses of engine 1 depend heavily on the viscosity of the engine oil, and the viscosity of the engine oil depends on the temperature of the engine oil. During idle operation, a large proportion of energy is consumed as heat, so the throttle opening (load) required to maintain a constant engine speed is greatly affected by the engine oil temperature. Furthermore, the engine oil temperature is strongly correlated with the coolant temperature of engine 1. Therefore, in this embodiment, the target throttle opening of the operating cylinder is set according to the coolant temperature of engine 1, thereby quickly stabilizing the shaft output of engine 1 and suppressing the decrease in engine speed.

[0027] Furthermore, during idle operation with all cylinders running (the fourth switch 55 is in a dashed line state), the integral value of the second integral controller 51 is repeatedly updated, so that when transitioning to a partially cylinder deactivated state, the integral value of the second integral controller 51 is reset. The second integral controller 51 is provided with a lookup table 56 that describes the correspondence between the engine 1 coolant temperature and the integral value. The lookup table 56 is referenced every cycle to update the integral value according to the engine 1 coolant temperature. Therefore, the second integral controller 51 sets the target throttle opening of the first cylinder 10 according to the engine 1 coolant temperature when transitioning to a partially cylinder deactivated state.

[0028] Furthermore, during idle operation, when some cylinders are deactivated (the third switch 49 is shown as a solid line), a fixed value is output to the second throttle opening controller 34 as the target throttle opening for the second cylinder (deactivated cylinder) 20. Generally, the larger the throttle opening for deactivated cylinders, the less pumping loss there is, and the better the fuel efficiency. However, even during idle operation, two-wheeled vehicles have higher engine speeds compared to four-wheeled vehicles, and the engine cycle is shorter relative to the time required to switch from idle to full throttle. Since pumping loss is strongly affected by the throttle opening during the intake stroke, it is preferable that the throttle opening switch converges within a period that avoids the intake stroke.

[0029] In this embodiment, considering the response speed of the actuator of the electronically controlled throttle valve, a fixed value is set as the target throttle opening for the second cylinder 20, which allows the throttle to be stabilized between the compression stroke and the exhaust stroke. Also, a larger throttle opening results in a louder engine noise. For this reason, the target throttle opening for the second cylinder 20 is set to a high opening that can converge from the opening when all cylinders are operating to a period that does not involve the intake stroke, while also making the engine noise acceptable. This reduces fluctuations in engine speed and engine noise, and stabilizes operation by switching the throttle opening before the intake stroke.

[0030] Furthermore, during idle operation, when some cylinders are deactivated (the first switch 42 is a solid line), the first adder element 43 of the first integral controller 41 adds "0" to the integral value input from the first delay element 44 every cycle. As a result, in the partial cylinder deactivation state, the integral value of the first integral controller 41 from the previous all-cylinders-operating state is retained, and when returning from the partial cylinder deactivation state to the all-cylinders-operating state, the target throttle opening from the previous all-cylinders-operating state is reset for all cylinders. Not only when transitioning to the partial cylinder deactivation state, but also when returning from the partial cylinder deactivation state, the shaft output of the engine 1 is quickly stabilized, reducing the decrease in engine speed.

[0031] The timing for switching the target throttle opening will be explained with reference to Figures 5 and 6. Figure 5 is a circuit diagram of the target throttle opening switching circuit in this embodiment. Figure 6 is a diagram showing the timing for switching the target throttle opening in this embodiment. Note that the cylinder deactivation timing is determined independently of the engine stroke depending on the vehicle speed, operating conditions, etc. Furthermore, the strokes and crank angles of the first and second cylinders are identified, for example, by protrusions provided at equal intervals in the circumferential direction of the crankshaft.

[0032] As shown in Figure 5, the throttle opening switching circuit 60 is equipped with first to third flip-flop circuits 61, 62, and 63 and a logic negation circuit 64. When the cylinder deactivation condition is not met (all cylinders are operating), a low-level signal is input to the input terminal of the logic negation circuit 64, and a high-level signal is output from the output terminal of the logic negation circuit 64 to the reset terminal R of the third flip-flop circuit 63. As a result, a high-level signal is output from the inverting output terminal Q- (indicated by a "-" above Q in the figure) of the third flip-flop circuit 63 to the reset terminal R of the first and second flip-flop circuits 61 and 62.

[0033] A low-level signal is output from the non-inverting output terminal Q of the first flip-flop circuit 61, and a high-level signal is output from the inverting output terminal Q- of the first flip-flop circuit 61. The first cylinder 10 is set to a normal target throttle opening based on the integral value of the first integral controller 41 (see Figure 4). A low-level signal is output from the non-inverting output terminal Q of the second flip-flop circuit 62, and a high-level signal is output from the inverting output terminal Q- of the second flip-flop circuit 62. Since all cylinders are operating, fuel is injected into the second cylinder 20 as usual.

[0034] A low-level signal is output from the non-inverting output terminal Q of the third flip-flop circuit 63, and a high-level signal is output from the inverting output terminal Q- of the third flip-flop circuit 63. The second cylinder 20 is set to a normal target throttle opening based on the integral value of the first integral controller 41 (see Figure 4). In this way, when all cylinders are operating, the target throttle openings of the first and second cylinders 10 and 20 are set based on the integral value of the first integral controller 41.

[0035] When the cylinder deactivation condition is met, a high-level signal is input to the set terminal S of the first flip-flop circuit 61 on the rising edge of the clock signal indicating the moment immediately after the intake valve of the first cylinder (operating cylinder) 10 closes. A high-level signal is output from the non-inverting output terminal Q of the first flip-flop circuit 61, and a low-level signal is output from the inverting output terminal Q- of the first flip-flop circuit 61. The switching circuit 60 switches the first cylinder 10 from the normal target throttle opening to the target throttle opening for deactivation. In this case, the target throttle opening for deactivation is set to an opening corresponding to the coolant temperature of the engine 1.

[0036] Next, on the rising edge of the clock signal indicating the moment immediately after the closing of the intake valve of the second cylinder (deactivated cylinder) 20, a high-level signal is input to the set terminal S of the second and third flip-flop circuits 62 and 63. A high-level signal is output from the non-inverting output terminal Q of the second and third flip-flop circuits 62 and 63, and a low-level signal is output from the inverting output terminal Q- of the second and third flip-flop circuits 62 and 63. Fuel injection to the second cylinder 20 is cut off, and the switching circuit 60 switches the second cylinder 20 from the normal target throttle opening to a fixed value target throttle opening for the deactivated cylinder.

[0037] Thus, after the cylinder deactivation decision is made, in which the first cylinder 10 becomes an active cylinder and the second cylinder 20 becomes a deactivated cylinder, the switching circuit 60 switches the first cylinder 10 from its normal target throttle opening to a target throttle opening for cylinder deactivation immediately after the intake stroke of the first cylinder 10. Furthermore, after the first cylinder 10's target throttle opening is switched to that for cylinder deactivation, the switching circuit 60 switches the second cylinder 20's target throttle opening to that for cylinder deactivation immediately after the intake stroke of the second cylinder 20. When the target throttle opening of the second cylinder 20 is switched, the switching circuit 60 decides to cut fuel for the second cylinder 20, and fuel injection for the second cylinder 20 is cut off during its exhaust stroke.

[0038] This ensures sufficient response time for the actuators of the first and second throttle valves 14 and 24 (see Figure 1) of the first and second cylinders (operating and deactivated cylinders) 10 and 20, allowing the throttle openings of the first and second cylinders 10 and 20 to be stabilized by the next intake stroke. This improves the pumping loss and output reproducibility of the first and second cylinders 10 and 20, and reduces variations in engine speed fluctuations with each cylinder deactivation decision. Furthermore, by aligning the timing of the target throttle opening switch for the second cylinder 20 with the timing of the fuel cut decision, the impact on engine speed is minimized.

[0039] As shown in Figure 6, the intake stroke intervals of the first cylinder 10 and the second cylinder 20 are unequal, at 270° and 450°. In this embodiment, the phase difference between the switching timing of the target throttle opening of the first cylinder 10 and the switching timing of the target throttle opening of the second cylinder 20 is set to 270°. That is, in the switching circuit 60 described above (see Figure 5), the phase difference of the rising edge of the clock signal indicating immediately after the closing of the intake valves of the first and second cylinders 10 and 20 is 270°. As a result, the delay in the switching of the throttle opening of the second cylinder 20 relative to the switching of the throttle opening of the first cylinder 10 is reduced, minimizing the impact on engine speed.

[0040] When the cylinder deactivation condition is met during the exhaust stroke of the first cylinder 10, the first cylinder 10 switches from its normal target throttle opening to a target throttle opening for cylinder deactivation during the compression stroke immediately following the intake stroke of the first cylinder 10. In the combustion stroke immediately following the compression stroke of the first cylinder 10, combustion occurs with the intake air volume before the switch. In the compression stroke immediately following the intake stroke of the second cylinder 20, which is 270° behind the intake stroke of the first cylinder 10, the second cylinder 20 switches from its normal target throttle opening to a target throttle opening for cylinder deactivation, and the fuel injection cut is decided. In the combustion stroke immediately following the compression stroke of the second cylinder 20, combustion occurs with the intake air volume before the switch, and fuel injection is stopped during the exhaust stroke immediately following the compression stroke.

[0041] In the first cylinder 10, the deactivation cycle begins from the first intake stroke after switching, and the same applies to the second cylinder 20. In the intake stroke after the start of the deactivation cycle of the first cylinder 10, intake is performed with a throttle opening for cylinder deactivation, and in the combustion stroke after the start of the deactivation cycle, combustion is performed with the intake volume after switching. In the intake stroke after the start of the deactivation cycle of the second cylinder 20, intake is performed with a throttle opening for cylinder deactivation, and no combustion occurs in the combustion stroke after the start of the deactivation cycle. Note that the cylinder deactivation conditions are not limited to the exhaust stroke of the first cylinder 10; stable switching can be achieved even if they are met during other strokes.

[0042] As described above, with the rotational speed control device 30 of this embodiment, when transitioning to a partial cylinder deactivation state during idle operation, the target throttle opening for the first cylinder (operating cylinder) 10 changes immediately without waiting for feedback on the engine speed after cylinder deactivation, thereby suppressing a rapid drop in engine speed. As a result, feedback on the engine speed relative to the target idle speed is received in time, preventing engine stalling, and reducing vibrations caused by a temporary drop in engine speed, thereby reducing driver discomfort during partial cylinder deactivation.

[0043] In this embodiment, the integral value of the second integral controller is reset to a value corresponding to the engine coolant temperature when transitioning to the partial cylinder deactivation state, but the configuration is not limited to this. It is sufficient that the integral value of the second integral controller is reset to a value corresponding to the target idle speed when transitioning to the partial cylinder deactivation state, and for example, the integral value of the second integral controller may be reset to a value corresponding to the engine oil temperature or viscosity.

[0044] Furthermore, in this embodiment, instead of adjusting the throttle opening of the throttle valve, the throttle opening of the ISC (Idle Speed ​​Control) valve installed in the bypass passage of the throttle body may be adjusted. If the ISC valve can be controlled for each cylinder, a similar effect can be obtained by determining the reset value of the integral controller of the idle speed controller of the ISC valve.

[0045] Furthermore, although a V-type twin-cylinder engine is used as an example in this embodiment, the engine is not particularly limited as long as it is possible to deactivate the operation of some cylinders during idle operation.

[0046] Furthermore, the engine speed control device of this embodiment is not limited to saddle-type vehicles, but may be applied to other vehicles as well. Note that saddle-type vehicles are not limited to all vehicles in which the driver sits straddling a seat, but also include scooter-type vehicles in which the driver does not straddle a seat.

[0047] As described above, the first embodiment is a rotational speed control device (30) for an engine (1) that deactivates the operation of some cylinders during idle operation, comprising: a first integral controller (41) that sets the target throttle opening for all cylinders based on the integral value of the deviation between the target idle speed and the engine speed when all cylinders are operating during idle operation; and a second integral controller (51) that sets the target throttle opening for the operating cylinder (first cylinder 10) based on the integral value of the deviation between the target idle speed and the engine speed when some cylinders are deactivated during idle operation, wherein when transitioning to the partial cylinder deactivation state, the integral value of the second integral controller is reset to a value corresponding to the target idle speed. With this configuration, when transitioning to the partial cylinder deactivation state during idle operation, the target throttle opening for the operating cylinder changes immediately without waiting for feedback on the engine speed after cylinder deactivation, thereby suppressing a rapid decrease in engine speed. This allows for timely feedback of engine speed relative to the target idle speed, preventing engine stalls and reducing vibrations caused by temporary drops in engine speed, thus mitigating driver discomfort during partial cylinder deactivation.

[0048] In the second embodiment, in the first embodiment, the integral value of the second integral controller is reset to a value corresponding to the engine coolant temperature when transitioning to a partial cylinder deactivation state. With this configuration, the target throttle opening of the operating cylinders is set according to the engine coolant temperature, and the engine shaft output is quickly stabilized when transitioning to partial cylinder deactivation, thereby reducing the decrease in engine speed.

[0049] In the third embodiment, as in the second embodiment, when all cylinders are operating, the integral value of the second integral controller is repeatedly updated according to the engine coolant temperature, and when some cylinders are deactivated, the integral value of the first integral controller from the previous all-cylinders operating state is retained. With this configuration, when transitioning to the some-cylinders deactivated state, a target throttle opening degree according to the engine coolant temperature is set for the operating cylinders, and when returning from the some-cylinders deactivated state, the target throttle opening degree from the previous all-cylinders operating state is reset for all cylinders. In both the transition to the some-cylinders deactivated state and the return from the some-cylinders deactivated state, the engine shaft output is quickly stabilized, and the decrease in engine speed is reduced.

[0050] In the fourth embodiment, in any one embodiment of the first to third embodiments, a fixed value is set as the target throttle opening for the deactivated cylinder (second cylinder 20) during a partial cylinder deactivation state, allowing the throttle to be stabilized between the compression stroke and the exhaust stroke. With this configuration, the target throttle opening for the deactivated cylinder is set to a fixed value so that the throttle opening switching converges within a period that avoids the intake stroke. Engine speed fluctuations are reduced, and the throttle opening is switched before the intake stroke, resulting in stable operation.

[0051] The fifth embodiment is one of the first to fourth embodiments, in which the engine is a V-type twin-cylinder engine, and the rear cylinder is a deactivated cylinder. With this configuration, when the V-type twin-cylinder engine is mounted on a saddle-type vehicle, the rear cylinder is located in the center of the vehicle in the longitudinal direction, where heat tends to accumulate. Therefore, by deactivating the operation of the rear cylinder, the heat generated during cylinder deactivation is suppressed, and heat damage to surrounding components is reduced.

[0052] Although this embodiment has been described, other embodiments may include combinations of the above embodiment and its modifications, either entirely or partially.

[0053] Furthermore, the technology of the present invention is not limited to the embodiments described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea. Moreover, if the technical idea can be realized in a different way by advances in the technology or by other derived technologies, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of symbols]

[0054] 1: Engine 10: First cylinder 20: Second cylinder 30: Rotation speed control device 41: First Integral Controller 51: The second integrating controller

Claims

1. An engine speed control device that deactivates the operation of some cylinders during idle operation, In idle operation with all cylinders running, a first integral controller sets the target throttle opening for all cylinders based on the integral value of the difference between the target idle speed and the engine speed, During idle operation, when some cylinders are deactivated, the system includes a second integral controller that sets the target throttle opening for the operating cylinders based on the integral value of the difference between the target idle speed and the engine speed. A rotational speed control device characterized in that, when transitioning to a partial cylinder deactivation state, the integral value of the second integral controller is reset to a value corresponding to the target idle speed.

2. The rotational speed control device according to claim 1, characterized in that when transitioning to a partial cylinder deactivation state, the integral value of the second integral controller is reset to a value corresponding to the engine's coolant temperature.

3. When all cylinders are operating, the integral value of the second integral controller is repeatedly updated according to the engine's coolant temperature. The rotational speed control device according to claim 2, characterized in that, when some cylinders are deactivated, the integral value of the first integral controller in the immediately preceding all-cylinders operating state is retained.

4. The rotational speed control device according to claim 1 or 2, characterized in that, in a partially deactivated cylinder state, a fixed value is set as the target throttle opening for the deactivated cylinder, which allows the throttle to be stabilized between the compression stroke and the exhaust stroke.

5. The rotational speed control device according to claim 1 or 2, characterized in that the engine is a V-type two-cylinder engine and the rear cylinder is a deactivated cylinder.

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