JP5675492B2 - Exhaust gas recirculation control device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas recirculation control device for an internal combustion engine, and more particularly, to an exhaust gas recirculation control device for an internal combustion engine that returns a part of exhaust gas to a combustion chamber and reburns it together with intake gas.

  Conventionally, an exhaust gas recirculation (EGR) system has been known that obtains effects such as exhaust gas purification and fuel efficiency improvement by reinhaling a portion of the exhaust gas from the internal combustion engine from the intake side and reburning it. It has been. Also, in an internal combustion engine equipped with a fuel injection device, so-called fuel cut control may be executed in which fuel injection is stopped at the time of deceleration when the throttle is fully closed at a predetermined vehicle speed or higher.

  Patent Document 1 discloses an EGR valve that opens and closes a bypass passage in an internal combustion engine to which an EGR system in which a part of exhaust gas is returned from the intake port to the combustion chamber by a bypass passage that connects the intake port and the exhaust port. A configuration is disclosed in which a learning process for optimizing the reference opening according to a secular change such as the adhesion of impurities is executed during the execution period of fuel cut control.

JP 2004-108329 A

  However, in the technique described in Patent Document 1, since the EGR valve opening learning process is performed during the fuel cut control, the EGR control is always executed during the fuel cut, and after the fuel cut control ends. It is considered that EGR control is switched from on to off. As a result, switching the EGR control to OFF may change the combustion state of the internal combustion engine, which may change the torque generated by the internal combustion engine. In particular, after the fuel cut, the throttle opening is often low and the engine torque is often low, so that the driver may easily feel torque fluctuation due to the EGR control being turned off.

  An object of the present invention is to provide an exhaust gas recirculation control device for an internal combustion engine that solves the above-described problems of the prior art and prevents a driver from feeling torque fluctuations associated with on / off of fuel cut control and EGR control. .

  In order to achieve the above object, the present invention combusts a part of exhaust gas by opening the exhaust valve (34) of the internal combustion engine (10) in a stroke other than the exhaust stroke in accordance with the operation of the actuator (61). In the exhaust gas recirculation control device for an internal combustion engine that executes EGR control for returning to the chamber (15z) and re-combusting, switching the operation non-operation state of the EGR control is performed by operating the actuator (61), The exhaust valve (34) is operated based on the cam profile of the variable cam member (50) that rotates in synchronization with the shaft (41), and the exhaust valve (34) based on the cam profile of the cam member (50). It is configured to be executed by switching between the state where the operation is not performed, and at least the engine speed (Ne) and the throttle opening (TH) are set. A control unit (100) for controlling the actuator (61) based on an EGR operation region map (101) as a parameter is provided, and the control unit (100) is configured to perform fuel cut conditions when the vehicle (1) is decelerated. Is satisfied, the fuel injection by the fuel injection device is cut, and the fuel cut condition is defined by at least the vehicle speed (V), the engine speed (Ne), and the throttle opening (TH). Is defined in the fuel cut map, and when the engine speed (Ne) falls below a predetermined value (NeL) on the low side, the fuel injection is cut and the fuel injection is resumed. The minimum value (Ne1) of the engine speed (Ne) constituting the EGR operating region (D) of the region map (101) is a low side predetermined value (NeL) of the fuel cut condition. There is a first feature in that it is set to a value higher than.

  The actuator (61) slides a variable cam member (50) attached so as to be slidable in the axial direction and not relatively rotatable with respect to the valve drive camshaft (41) that drives the exhaust valve (34). The EGR control is switched between the non-operating state and the non-engagement with the exhaust valve (34) by sliding the variable cam member (50) by the actuator (61). When the EGR control is not in operation, the exhaust valve (34) is switched between an exhaust cam lobe (42e) and an exhaust rocker arm (44e) fixed to the valve drive camshaft (41). And the variable cam member (50) and the exhaust cam lobe (42e) are both driven by the exhaust rocker arm (44) when the EGR control is activated. ) That there is a second feature in that it is adapted to be driven by engagement with.

  Further, the fuel cut amount is gradually reduced between the minimum value (Ne1) of the engine speed (Ne) constituting the EGR operation region (D) and the low side predetermined value (NeL) of the fuel cut condition. A third feature is that a high-side predetermined value (NeH) is set as the start timing of the fuel cut amount gradual reduction control.

  Further, the difference between the high side predetermined value (NeH) and the minimum value (Ne1) is set larger than the difference between the low side predetermined value (NeL) and the high side predetermined value (NeH). This is the fourth feature.

  In addition, the control unit (100) starts a counter as the fuel cut amount gradual decrease control starts, and when the counter reaches a predetermined value, terminates the fuel cut amount gradual decrease control and the fuel cut and performs fuel injection. There is a fifth feature in that it is configured to return.

  The EGR operating region map (101) is defined by a two-dimensional map consisting of the engine speed (Ne) and the throttle opening (TH), and the EGR operating region (D) is the engine speed (Ne). From a rectangle formed by a predetermined range (Ne1 to Ne2) of the throttle and a predetermined range (0 to TH2) of the throttle opening (TH), the engine speed (Ne) is low and the throttle opening (TH) is high. There is a sixth feature in that it is formed by excluding a predetermined range of a substantially triangular shape.

  The fuel cut condition has a seventh feature in that the throttle opening (TH) includes a fully closed state.

  Further, the EGR operation region map (101) has an eighth feature in that a hysteresis setting region (E) for providing hysteresis characteristics to the EGR operation region (D) is provided.

  According to the first and second features, the actuator is configured to be slidable on a variable cam member that is slidable in the axial direction and is relatively non-rotatable with respect to the valve drive camshaft that drives the exhaust valve. The EGR control operation / non-operation state is switched by sliding the variable cam member with an actuator to switch the engagement / disengagement state with the exhaust valve. During operation, the exhaust cam lobe fixed to the valve camshaft is driven while the exhaust rocker arm is engaged. During EGR control operation, both the variable cam member and the exhaust cam lobe are engaged with the exhaust rocker arm. Based on an EGR operating region map using at least the engine speed and the throttle opening as parameters. A control unit that controls the actuator, and the control unit is configured to cut the fuel injection by the fuel injection device when the fuel cut condition is satisfied, for example, when the vehicle is decelerated, and the fuel cut condition is at least Defined by fuel cut map defined by vehicle speed, engine speed and throttle opening, and set to stop fuel injection and return fuel injection when engine speed falls below a predetermined value on the low side Since the minimum value of the engine speed constituting the EGR operating region of the EGR operating region map is set to a value higher than the predetermined value on the low side of the fuel cut condition, fuel injection is executed during deceleration. In this state, straddling between the EGR operating region and the EGR non-operating region is prevented.

  For example, if the fuel injection is being performed during deceleration and the EGR non-operating region is switched to the EGR operating region, the combustion state becomes more favorable due to EGR control, and the engine output may change in a direction that improves. There is. Then, the engine output is improved during deceleration with the throttle off, which may affect drivability. On the other hand, according to the setting according to the present invention, it is during fuel cut control in which fuel injection is not performed that straddles the EGR operating region, so that EGR control is not operated without affecting the engine output. Can be switched.

  According to the third feature, the start timing of the fuel cut amount gradual reduction control that gradually reduces the fuel cut amount between the minimum value of the engine speed constituting the EGR operation region and the low side predetermined value of the fuel cut condition. As the high-side predetermined value is set as follows, by gradually reducing the fuel cut amount from the fuel cut control state, fluctuations in engine output at the time of fuel re-injection (at the time of fuel injection return) are suppressed, Furthermore, drivability can be improved.

  According to the fourth feature, since the difference between the high-side predetermined value and the minimum value is set larger than the difference between the low-side predetermined value and the high-side predetermined value, the fuel cut amount gradual decrease control is performed. The period from the start to the end can be set short, and the fuel consumption during this period can be reduced.

  According to the fifth feature, the control unit activates a counter as the fuel cut amount gradual decrease control starts, and when the counter reaches a predetermined value, terminates the fuel cut amount gradual decrease control and the fuel cut and performs fuel injection. Therefore, the period from the start to the end of the fuel cut amount gradual reduction control can be arbitrarily changed by changing the condition for incrementing the counter and the setting of the predetermined value. Thereby, even when the type of the internal combustion engine is different, the fuel cut amount gradual reduction control can be executed smoothly.

  According to the sixth feature, the EGR operating region map is defined by a two-dimensional map including the engine speed and the throttle opening, and the EGR operating region includes a predetermined range of the engine speed and a predetermined range of the throttle opening. The EGR control is deactivated in a predetermined triangular area in the two-dimensional map, because a predetermined range of a substantially triangular shape having a low engine speed and a high throttle opening is excluded from the rectangular formed by Thus, it is possible to improve the engine output and the effect of exhaust gas purification.

  According to the seventh feature, since the fuel cut condition includes that the throttle opening is in the fully closed state, the fuel cut control is executed after confirming the occupant's intention to decelerate based on the throttle opening. Is possible.

  According to the eighth feature, the EGR operation region map is provided with a hysteresis setting region for giving hysteresis characteristics to the EGR operation region, so that excitation and demagnetization of the electromagnetic solenoid are repeated near the boundary of the EGR operation region. Can be prevented.

1 is a left side view of a motorcycle to which an exhaust gas recirculation control device for an internal combustion engine according to an embodiment of the present invention is applied. It is an enlarged side view of an internal combustion engine. It is a partial expanded sectional view of the internal combustion engine seen from the vehicle body right side. It is a partial expanded sectional view of the internal combustion engine seen from the vehicle body back. It is the VV sectional view taken on the line of FIG. It is a disassembled perspective view of a valve drive cam shaft, a steady cam member, and a variable cam member. It is assembly sectional drawing of a valve cam shaft, a steady cam member, and a variable cam member. FIG. 8 is a sectional view taken along line 8-8 in FIG. 7. It is a perspective view of a rocking arm. It is a top view of a cylinder head. 1 is a block diagram illustrating a configuration of an exhaust gas recirculation control device for an internal combustion engine according to an embodiment of the present invention. It is a graph which shows the drive timing of an intake / exhaust valve. It is a data map which prescribes | regulates the area | region which performs EGR control. It is a flowchart which shows the procedure of EGR cam drive solenoid control. It is a flowchart which shows the procedure of the fuel cut control at the time of deceleration.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a left side view of a motorcycle 1 to which an exhaust gas recirculation control device for an internal combustion engine according to an embodiment of the present invention is applied. FIG. 2 is an enlarged side view of the internal combustion engine 10. An internal combustion engine 10 that is a four-cycle single-cylinder gasoline engine is mounted on the body frame 2 of the motorcycle 1 with the crankshaft 11 oriented in the vehicle width direction.

  The vehicle body frame 2 includes a head pipe 2h, a pair of left and right main frames 2m, 2m extending from the head pipe 2h to the rear lower side of the vehicle body, and steeply inclined portions 2ma, 2ma bent downward from the rear ends of the main frames 2m, 2m. It is. Furthermore, one down frame 2d extending rearward and downward from the head pipe 2h at a steep angle is disposed substantially parallel to the steeply inclined portions 2ma and 2ma of the main frames 2m and 2m.

  A pair of left and right seat rails 2s, 2s extend rearward from the upper portions of the steeply inclined portions 2ma, 2ma via gussets 2g, 2g. The seat rails 2s, 2s are supported from below by back stays 2b, 2b connected to the lower portions of the steeply inclined portions 2ma, 2ma.

  A pair of left and right front forks 3 are swingably supported on the head pipe 2h, and a front wheel Fw is rotatably supported at the lower end thereof. A swing arm 4 that rotatably supports the rear wheel Rw is pivotally supported below the steeply inclined portions 2ma and 2ma, and a rear cushion 5 is interposed between the swing arm 4 and the gussets 2g and 2g. Is intervening. A fuel tank 6 is installed above the main frames 2m, 2m so as to straddle from above, and a seat 7 supported by seat rails 2s, 2s is disposed behind the fuel tank 6.

  The internal combustion engine 10 suspended from the main frames 2m, 2m and the down frames 2d, 2d is a transmission-integrated SOHC engine, and the cylinder block 14, the cylinder head 15, and the head cover 20 are arranged in a slightly inclined posture. It is installed. An air cleaner box 8a is attached to the rear portion of the cylinder head 15 via an intake pipe 8 in which a throttle valve is provided. On the other hand, an exhaust pipe 9 connected to a muffler 9m at the rear of the vehicle body is attached to the front portion of the cylinder head 15.

  The internal combustion engine 10 according to the present embodiment opens an exhaust valve at an arbitrary timing during the intake stroke, thereby returning a part of the exhaust gas from the exhaust port to the combustion chamber and reburning it (EGR system). It has. Specifically, the camshaft that drives the exhaust valve is provided with a cam lobe for normal operation and a cam lobe for EGR control, and is operated during normal operation by arbitrarily operating the cam lob for EGR control. No exhaust valve operation for EGR control is performed. An electromagnetic solenoid 61 as an actuator for driving a cam lobe for EGR control is attached to the head cover 20 of the internal combustion engine 10.

  Referring to FIG. 2, a crankcase 13 that supports the crankshaft 11 is formed with a transmission chamber 13M that houses a transmission behind a crank chamber 13C in which the crankshaft 11 is disposed. The output shaft 12 of the transmission projects to the left in the vehicle width direction. An oil sump 13P for storing oil is integrally formed below the crank chamber 13C.

  Further, FIG. 3 is also referred to. FIG. 3 is a partially enlarged sectional view of the internal combustion engine 10 as viewed from the right side of the vehicle body. The crankcase 13 forming the crank chamber 13C, the transmission chamber 13M, and the oil reservoir 13P has a left-right split structure in the vehicle width direction. A cylinder head 15 including a cylinder block 14 into which a sleeve 14a is inserted and a valve mechanism 40 is overlaid on an upper portion of the crank chamber 13C.

  The camshaft holder 16, the cylinder head 15, and the cylinder block 14 are integrally fastened to the crankcase 13 by a head bolt 17. A head cover 20 is disposed above the cylinder head 15 via an elastic seal member 18. A piston 31 is fitted in the sleeve 14a of the cylinder block 14 so as to be slidable in a reciprocating manner, and the piston 31 and the crankshaft 11 are connected by a connecting rod 32 to constitute a crank mechanism.

  A combustion chamber 15z is formed in the cylinder head 15 so as to face the piston 31 in the cylinder axial direction, and an intake port 15i extends from the combustion chamber 15z to the rear of the vehicle body, while from the combustion chamber 15z to the front of the vehicle body. The exhaust port 15e extends.

  The intake valve 33 and the exhaust valve 34 are slidably supported by a valve guide that is integrally fitted to the cylinder head 15. The intake valve 33 and the exhaust valve 34 are driven by the valve mechanism 40 to open and close the intake opening of the intake port 15i and the exhaust opening of the exhaust port 15e in synchronization with the rotation of the crankshaft 11.

  FIG. 4 is a partially enlarged cross-sectional view of the internal combustion engine 10 as viewed from the rear of the vehicle body. The spark plug 19 is attached to the cylinder head 15 so that the tip thereof is inserted from the ceiling side of the combustion chamber 15z. The valve mechanism 40 is driven by a single valve camshaft (camshaft) 41 that is pivotally supported by the camshaft holder 16 in the vehicle width direction.

  Rocker arm shafts 43e and 43i are supported on the camshaft holder 16 at positions above the valve camshaft 41 and at the front and rear of the vehicle body. An intake rocker arm 44i is pivotally supported on the rear rocker arm shaft 43i, while an exhaust rocker arm 44e is pivotally supported on the front rocker arm shaft 43e.

  A cylindrical steady cam member 42 in which an intake cam lobe 42 i and an exhaust cam lobe 42 e are formed side by side is press-fitted into the valve operating cam shaft 41. A driven cam chain sprocket 36 is fixed to the left end of the valve camshaft 41 in the vehicle width direction.

  A driving cam chain sprocket 35 is fixed to the crankshaft 11, and an endless cam chain 37 is stretched between the driving cam chain sprocket 35 and the driven cam chain sprocket 36 (see FIG. 2). . The rotational power of the crankshaft 11 is transmitted to the valve drive camshaft 41 at half the rotational speed of the crankshaft 11. As a result, the intake rocker arm 44i and the exhaust rocker arm 44e swing in synchronization with the crankshaft 11, and the intake valve 33 and the exhaust valve 34 are driven to open and close at a required timing.

  Cam chain chambers 14c, 15c, and 20c are formed as one communicating cavity on the left side in the vehicle width direction of the cylinder block 14, the cylinder head 15, and the head cover 20. The cam chain 37 is guided in the cam chain chambers 14c, 15c, and 20c by a chain guide 38 that extends linearly in the vertical direction, and the rear side portion is suppressed by an arcuately curved tension slipper 39. And maintain proper tension. The rear side of the tension slipper 39 is pressed by a tensioner lifter 39t.

  5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is an exploded perspective view of the valve drive cam shaft 41, the steady cam member 42, and the variable cam member 50. The same reference numerals as those described above denote the same or equivalent parts. The valve camshaft 41 is a cylindrical member having a central shaft hole 41h and is accurately formed by cold forging.

At the center of the valve cam shaft 41 in the axial direction, a spline forming portion 41c having a maximum outer diameter having six spline grooves 41cs is formed. On the right side of the spline forming portion 41c in the vehicle width direction, a cam fixing portion 41r having a reduced diameter is formed through a step portion, and a further reduced diameter journal portion 41j is formed on the right end thereof. Further, a left cylindrical part 41l having a slightly reduced diameter is formed on the left side of the spline forming part 41c. The two spline grooves 41cs, 41cs located diagonally are respectively formed with long holes 41s, 41s having the same shape that are elongated in the axial direction. A key groove 41 k is formed at the left end of the valve camshaft 41.

  A steady cam member 42 having an exhaust cam lobe 42e and an intake cam lobe 42i is press-fitted and fixed at a predetermined relative angle to the cam fixing portion 41r. The steady cam member 42 is press-fitted from the right side of the cam fixing portion 41r until it contacts the spline forming portion 41c so that the exhaust cam lobe 42e is positioned on the left side in the vehicle width direction. As a result, the exhaust cam lobe 42e is integrated with the valve camshaft 41 adjacent to the spline forming portion 41c.

  On the other hand, the variable cam member 50 as an EGR cam for opening the exhaust valve 34 and executing EGR control during the intake stroke is spline-fitted to the spline forming portion 41 c of the valve operating cam shaft 41. On the inner peripheral surface of the variable cam member 50, six spline protrusions 50cs are formed that fit into the spline grooves 41cs formed on the valve operating cam shaft 41. A variable cam lobe 50e is formed at the right end of the outer peripheral surface of the variable cam member 50 in the vehicle width direction.

  Most of the outer periphery of the variable cam lobe 50e forms a basic circle having the same diameter as or slightly smaller than the basic circle of the exhaust cam lobe 42e, and a cam crest for EGR control with a small lift amount projects at a predetermined phase angle. On the other hand, in the cylindrical portion where the variable cam lobe 50e is not formed, pin holes 50p and 50p that pass through the spline protrusions 50cs and 50cs formed on the inner peripheral portion of the variable cam member 50 and are orthogonal to the central axis are formed. Has been. Further, an outer peripheral groove 50v passing through the outer opening of the pin holes 50p, 50p is formed on the outer peripheral surface of the cylindrical portion.

  When this variable cam member 50 is spline-fitted with a predetermined relative angle from the left side in the vehicle width direction to the spline forming portion 41c of the valve camshaft 41, the pin holes 50p and 50p of the variable cam member 50 are connected to the valve camshaft. It will correspond to 41 long holes 41s and 41s.

  FIG. 7 is an assembly cross-sectional view of the valve drive cam shaft 41, the steady cam member 42 and the variable cam member 50. 8 is a cross-sectional view taken along line 8-8 of FIG. The valve camshaft 41 is rotated with respect to the camshaft holder 16 (see FIG. 4) by a bearing 46 fitted to the right journal portion 41j and a bearing 45 fitted to the left cylindrical portion 41l. It is supported freely. The bearing 45 is sandwiched between the spline forming portion 41c when the flange member 47 is press-fitted into the left cylindrical portion 41l through a key 49 at a predetermined relative angle.

  At the left end of the flange member 47 in the figure, flange portions 47f and 47f bulging in the radial direction are formed. The drive cam chain sprocket 36 is attached to the flange member 47 by screwing screws 48, 48 into the screw holes 47h, 47h formed in the screw holes 36h, 36h and the flange portions 47f, 47f. The left end of the valve camshaft 41 engages with the center hole 36 c of the drive cam chain sprocket 36.

  A slide rod 53 constituting a slider mechanism 52 for slidably displacing the variable cam member 50 is inserted into the central shaft hole 41h of the valve camshaft 41 so as to be slidable in the axial direction. In the slide rod 53, both sides of the central large diameter portion 53c are slightly reduced in diameter, and a pin hole 53p is formed in the central large diameter portion 53c so as to be orthogonal to the axial direction.

  The slide mechanism 52 inserts the slide rod 53 into the central shaft hole 41h of the valve camshaft 41, and then pins the elongated holes 41s and 41s of the valve camshaft 41 and the pin holes 50p and 50p of the variable cam member 50. The holes 53p are matched and assembled by inserting one connecting pin 54 between the matched pin holes 50p, 50p, the long holes 41s, 41s and the pin hole 53p.

  The connecting pin 54 is formed shorter than the inner diameter of the outer peripheral groove 50v formed in the variable cam member 50, and is prevented from coming off by a retaining ring 55 fitted in the outer peripheral groove 50v. As a result, the connecting pin 54 engages with the pin holes 50p, 50p of the both-end variable cam member 50 and moves integrally with the variable cam member 50. Accordingly, when the slide rod 53 slides in the left-right axial direction within the central shaft hole 41h, the connection pin 54 is guided and moved by the long holes 41s and 41s, and the variable cam member 50 is integrated with the connection pin 54. Moves in the axial direction.

  A female screw is formed on the inner peripheral surface of the right end of the central shaft hole 41 h of the valve camshaft 41. A flanged bolt 57 is screwed into the central shaft hole 41 h after the coil spring 56 is inserted from the right side. Thus, a coil is formed between the central large diameter portion 53 c of the slide rod 53 and the flanged bolt 57. A slider mechanism 52 is configured in which the spring 56 is sandwiched and the slide rod 53 is always urged to the left.

  The valve camshaft 41 protrudes in opposition to the left and right of the camshaft holder 16 in a small assembly state in which a stationary cam member 42, a variable cam member 50, a driven cam chain sprocket 36, and bearings 45 and 46 are attached to the outer periphery thereof. The left and right bearing walls 16 (16L, 16R; see FIG. 4) are inserted from the left side in the vehicle width direction. The valve camshaft 41 is fitted to the camshaft holder 16 by fitting the right bearing 46 into the shaft hole of the right bearing wall 16R and the left bearing 45 into the shaft hole of the left bearing wall 16L. The shaft is rotatably supported, and rotates together with the steady cam member 42 and the variable cam member 50.

  The right bearing 46 is positioned in contact with the step of the right bearing wall 16R, and the left bearing 45 is positioned by a stop plate 59 fixed to the left bearing wall 16L with a bolt 58 ( (See FIG. 4).

  Referring to FIG. 4, when the slide rod 53 urged to the left by the coil spring 56 is pushed to the right against the urging force of the coil spring 56, as shown by the solid line in FIG. The variable cam member 50 slides and displaces to the right in the drawing via the pin 54. Thus, the variable cam member 50 comes close to the exhaust cam lobe 42e, and the roller 44er of the exhaust rocker arm 44e comes into contact with both the exhaust cam lobe 42e and the variable cam lobe 50e. For this reason, the exhaust valve 34 for performing EGR (exhaust gas recirculation) can be opened and closed separately from the normal opening and closing timing of the exhaust valve 34 by the exhaust cam lobe 42e. The roller 44ir (see FIG. 3) of the intake rocker arm 44i is configured to contact only the intake cam lobe 42i.

  On the other hand, when the slide rod 53 is moved to the left by the coil spring 56, the variable cam member 50 is slid to the left in the drawing as shown by a two-dot chain line in FIG. 4, and is variable with the roller 44er of the exhaust rocker arm 44e. The cam lobe 50e is not in contact. Thereby, the exhaust valve 34 opens and closes at a normal exhaust valve timing by the exhaust cam lobe 42e.

  The variable valve timing drive mechanism 60 that presses the slide rod 53 to the right is provided on the left side of the driven cam chain sprocket 36 in the vehicle width direction. The variable valve timing drive mechanism 60 includes an electromagnetic solenoid 61 as an actuator and a swing arm 65 that transmits the drive of the electromagnetic solenoid 61 to the slider mechanism 52. The electromagnetic solenoid 61 is fixed above the ceiling wall 20 u of the head cover 20, and the swing arm 65 is pivotably supported in the cam chain chamber 20 c of the head cover 20.

  The head cover 20 is formed in a generally rectangular bowl shape by the ceiling wall 20u and the peripheral wall 20s. The ceiling wall 20u is formed with a concave portion 20uh in which the cylindrical electromagnetic solenoid 61 is accommodated and convex portions 20up and 20up adjacent to the concave portion 20uh in the longitudinal direction of the vehicle body (see FIGS. 3 and 4). On the left side of the head cover 20 in the vehicle width direction, a central protruding portion 21 that extends upward to a position covering the electromagnetic solenoid 61 is formed, and protruding boss portions 22, 22 extend in the vehicle longitudinal direction of the central protruding portion 21. Is formed (see FIG. 5).

  The central protrusion 21 is formed with a central gap 21c having a width into which the swing arm 65 can be inserted. A circular hole 21h directed in the vehicle width direction on the axis of the electromagnetic solenoid 61 is formed in the central protrusion 21 so as to reach the central gap 21c. An attachment cylindrical portion 62b that fits into the circular hole 21h is provided on one end face of the electromagnetic solenoid 61, and a plunger 61p as an operating shaft projects from the attachment cylindrical portion 62b. Mounting flange portions 62f and 62f extend on the front and rear portions of the outer peripheral surface of the electromagnetic solenoid 61 (see FIG. 4).

  The electromagnetic solenoid 61 inserts the mounting cylindrical part 62b into the circular hole 21h, contacts the mounting flanges 62f and 62f with the projecting boss parts 22 and 22, and then attaches the female thread formed on the projecting boss parts 22 and 22 to the female screw. The bolts 63 are fixed to the head cover 20 by screwing. The axial direction of the plunger 61p of the electromagnetic solenoid 61 is parallel to the axial direction of the valve operating cam shaft 41 and the slide rod 53 in the central shaft hole 41h.

  The rigidity of the head cover 20 is enhanced by forming the concave portion 20uh and the convex portions 20up, 20up. Further, by fixing the electromagnetic solenoid 61 so as to be accommodated in the recess 20uh, the upward protrusion amount of the electromagnetic solenoid 61 is reduced.

  A pair of guide walls 23, 23 are formed extending downward on the front and rear sides of the central gap 21 c formed in the central protrusion 21. An elastic stopper piece 29 is attached to the peripheral wall 20s of the head cover 20 to prevent the swing arm 65 from coming into contact with the peripheral wall 20s.

  FIG. 9 is a perspective view of the swing arm 65. The swing arm 65 is a member having a U-shaped cross-section in which long and identical side plate portions 65b and 65b facing each other are connected by a long connecting plate portion 65a. The swing arm 65 is disposed in the cam chain chamber 20c of the head cover 20 so as to be oriented substantially parallel to the cylinder axial direction. The side plate portions 65b and 65b are provided with shaft support holes 65bh and 65bh at positions deviated upward from the center, and are formed so as to be tapered from the shaft support holes 65bh and 65bh up and down.

  The upper half of the swing arm 65 is inserted into the central gap 21c of the central protrusion 21, and the pivot holes 65bh and 65bh are made to coincide with the pivot holes formed in the front and rear side surfaces of the central gap 21c. Is pivotally supported by the head cover 20 by being screwed through.

  The slide rod 53 that slides within the valve camshaft 41 is disposed on substantially the same plane as the mating surface S (the lower surface of the elastic seal member 18) between the head cover 20 and the cylinder head 15, and the swing arm 65 is provided. The lower end of the projection slightly protrudes downward from the mating surface S. On the other hand, lower ends 23 a and 23 a of the pair of front and rear guide walls 23 and 23 extending downward from the central projecting portion 21 are located above the slide rod 53. The stopper pieces 24 and 24 with which the swing arm 65 abuts are disposed above the lower ends of the guide walls 23 and 23 (see FIG. 5).

  Since the swing arm 65 is pivotally supported by the pivot bolt 64 at a position offset from the center to the upper portion, the lower portion is longer than the pivot bolt 64. As shown in FIG. The pivot bolt 64 serving as the fulcrum P is positioned above the driven cam chain sprocket 36 fixed to the valve camshaft 41. The plunger 61p of the electromagnetic solenoid 61 contacts the connecting plate portion 65a at the upper end, and the slide rod 53 biased by the coil spring 56 contacts the connecting plate portion 65a at the lower end of the pivot bolt 64.

  When the mounting cylindrical portion 62b of the electromagnetic solenoid 61 is inserted into the circular hole 21h of the central projecting portion 21, the plunger 61p retracted in the demagnetized state of the electromagnetic solenoid 61 abuts against the upper end of the swing arm 65 to push and swing. The lower end of the swing arm 65 is in contact with the left end of the slide rod 53 urged by the coil spring 56 and is in the state indicated by the two-dot chain line in FIG. That is, the lower end of the swing arm 65 is biased by the coil spring 56 via the slide rod 53, and does not swing freely. Therefore, even if the plunger 61p is retracted by driving the electromagnetic solenoid 61, the plunger 61p and the upper end of the swing arm 65 are always kept in contact with each other, and the lower end of the swing arm 65 and the slide rod 53 are always in contact with each other. Since power is transmitted to the slide rod 53 in a state in which is maintained, collision noise between the swing arm 65 and the slide rod 53 does not occur.

  When the electromagnetic solenoid 61 is driven, the swinging movement of the swinging arm 65 is restricted by contacting the stopper piece 24, so that the sliding of the variable cam member 50 together with the slide rod 53 to the right is also performed at a predetermined position. Therefore, the variable cam member 50 stops at a close position slightly away from the steady cam member 42.

  Since the electromagnetic solenoid 61 supported by the head cover 20 is located below the fuel tank 6, its operating sound is blocked by the fuel tank 6 and is not easily transmitted to the occupant. Further, since the electromagnetic solenoid 61 is protected by the fuel tank 6, a shielding member dedicated to the electromagnetic solenoid is not required, and the number of parts can be reduced.

  Referring to FIG. 4, the swing arm 65 has a force point Q at the upper end where the plunger 61 p of the electromagnetic solenoid 61 abuts, and the lower end point abutted against the slide rod 53, where the pivot center by the pivot bolt 64 is the fulcrum P. Is the point of action R. The swing arm 65 receives the plunger 61p protruding leftward by the excitation drive of the electromagnetic solenoid 61 at the force point Q, swings, and slides the slide rod 53 to the right at the action point R at the lower end. On the other hand, when the electromagnetic solenoid 61 is demagnetized, the slide rod 53 slides to the left by the biasing force of the coil spring 56, and the plunger 61p of the electromagnetic solenoid 61 is pushed to the right.

  That is, when the electromagnetic solenoid 61 is demagnetized, the slide rod 53 slides to the left by the biasing force of the coil spring 56, and the variable cam member 50 slides to the left to move away from the steady cam member 42. The exhaust valve 34 opens and closes at normal exhaust valve timing. On the other hand, when the electromagnetic solenoid 61 is excited, the plunger 61p protrudes to the left, so that the slide rod 53 slides to the right against the urging force of the coil spring 56, and the variable cam is connected via the connecting pin 54. The member 50 is slid rightward and switched to a state in which the exhaust valve 34 is opened and closed by the variable cam lobe 50e separately from the normal opening and closing timing of the exhaust valve 34 by the exhaust cam lobe 42e.

  The opening / closing timing of the exhaust valve 34 different from the normal exhaust timing is executed at a predetermined timing that overlaps the opening timing of the intake valve 33, and the exhaust gas remaining in the exhaust port by the opening of the exhaust valve 34 is removed from the combustion chamber. It becomes possible to return to 15z.

The swing arm 65, the with the longitudinal direction are arranged directed substantially parallel to the cylinder axis direction (substantially vertical direction), above the driven cam chain sprocket 36 secured to the valve operating cam shaft 41 Therefore, the swing arm 65 can be incorporated into the valve gear 40 in a compact manner while increasing the lever ratio.

  Further, since the swing arm 65 is linearly located in order from the top to the bottom, the force point Q, the fulcrum P, and the action point R, the swing arm 65 can be easily incorporated into the narrow space of the cam chain chamber 20c. While reducing the weight of the arm 65, the swinging arm 65 is prevented from being applied with a twisting force. Further, since the swing arm 65 has a U-shaped cross section, the swing arm 65 is reduced in weight, and the rigidity is ensured to prevent the swing arm 65 from being bent. As a result, the operation of the electromagnetic solenoid 61 can always be accurately moved and transmitted to the slider mechanism 52 to displace the variable cam member 50, and the valve timing can be changed smoothly and accurately, and EGR control can be performed efficiently. It can be done well.

It should be noted that many reinforcing ribs are provided on the back side of the head cover 20, particularly below the central projecting portion 21. Thereby, the rigidity of the central projecting portion 21 and the projecting boss portions 22, 22 that cantilever-support the electromagnetic solenoid 61 is ensured, and the plunger 61 p of the electromagnetic solenoid 61 fixed to the projecting boss portions 22, 22 is driven by the slider mechanism 52. Will be transmitted accurately. Further, since the lever ratio of the swing arm 65 is large, the drive amount of the electromagnetic solenoid 61 is small, and a small actuator can be used. Furthermore, the head cover 20, since the integrally formed a pair of guide walls 23 and 23 to support the pivot shaft may be less simple structure of parts.

  FIG. 10 is a top view of the cylinder head 15. An oil passage 26 is formed on the back surface of the ceiling wall 20u of the head cover 20 so that the front is located on the left side with respect to the longitudinal direction of the vehicle body. The oil passage 26 is provided with four injection holes 27 directed downward. Further, three knock holes 15n are formed on the upper surface of the cylinder head 15, and the knock members 72 are fitted into the knock holes 15, respectively.

  When the head cover 20 is put on the upper part of the cylinder head 15, positioning is performed by fitting a knock member 72 into a knock hole 15n provided on the head cover 20 side, and the mounting bolt hole 15b is flanged via an elastic member 71. The bolt 70 is passed through and tightened. As a result, the head cover 20 is regulated by the knock member 72 in the direction perpendicular to the cylinder axis and is elastically supported with respect to the cylinder head 15, whereby the variable valve timing drive mechanism 60 is operated. The influence of the vibration that has an influence is absorbed, and the change of the valve timing can be executed with high accuracy.

  The knock hole 15n adjacent to the oil passage 26 on the rear side of the cylinder head 15 communicates with the oil supply passage 15a extending from the cylinder block 14 side and communicates with the oil passage 26. As a result, the oil supplied from the oil supply passage 15 a is supplied to the oil passage 26 via the cylindrical knock member 72.

  As shown by a two-dot chain line in FIG. 10, the oil passage 26 is formed to extend obliquely in the front-rear direction above the intake rocker arm 44i and the exhaust rocker arm 44e. In the middle of the oil passage 26, four injection holes 27 are provided, and oil is sprayed onto the intake rocker arm 44i and the exhaust rocker arm 44e to lubricate the valve mechanism 40.

  The oil sprayed from the injection hole 27 of the oil passage 26 to the valve mechanism 40 also lubricates the spline fitting portion with the valve camshaft 41 on which the variable cam member 50 slides, so that the variable cam member 50 becomes a steady cam. Oil also enters the gap between the two when they are close to the member 42. However, in this embodiment, since the swing arm 65 abuts against the stopper piece 24 and the vibration is restricted, a gap is provided between the variable cam member 50 and the steady cam member 42. Therefore, the variable cam member 50 and the steady cam member 42 are not easily separated from each other.

  The oil sprayed on the valve mechanism 40 and the oil scooped up by the cam chain 37 are splashed up by rocking of the rocker arms 44 i and 44 e accompanying the rotation of the valve cam shaft 41 and the rotation of the cam chain 37. . As a result, the rocking shaft portion of the rocking arm 65 is always lubricated with oil, and wear of the contact portion between the rocking arm 65 and the slide rod 53 is prevented.

  FIG. 11 is a block diagram showing a configuration of an exhaust gas recirculation control device for an internal combustion engine according to an embodiment of the present invention. An ECU 100 serving as a control unit that functions as an exhaust gas recirculation control device for an internal combustion engine includes a Ne (engine speed) sensor 102, a Tw (temperature) sensor 103, a TH (throttle opening) sensor 104, and a Pb (intake pressure) sensor. Information from 105 is input respectively. Note that the position where the internal combustion engine 10 is in two rotations of the crankshaft (720 degrees) is determined based on the crank pulse information of the crankshaft 11 detected by the Ne sensor 102 and the output value of the Pb sensor 105 (front and back). (Determination). The ECU 100 also determines the ignition timing of the spark plug 19 and the amount of fuel injected into the combustion chamber based on each sensor information. The Tw sensor 103 can be configured to detect the lubricating oil temperature when the internal combustion engine 10 is an air-cooled engine, and to detect the cooling water temperature when the internal combustion engine 10 is a water-cooled engine.

  In the present embodiment, an EGR operation region map 101 (see FIG. 13) that defines an operation state in which EGR control is executed is housed in the ECU 100. The ECU 100 compares the sensor information of the Ne sensor 102 and the TH sensor 104 with the EGR operation region map 101 to determine whether or not the current operation state of the internal combustion engine 10 is an operation state suitable for EGR control. It is configured.

  When the ECU 100 determines that the driving state is suitable for EGR control, the electromagnetic solenoid 61 is excited to engage the variable cam member 50 (see FIG. 4) with the exhaust rocker arm 44e and execute EGR control. If it is determined that the operation state is not suitable for the EGR control, the electromagnetic solenoid 61 is demagnetized to release the engagement between the variable cam member 50 and the exhaust rocker arm 44e, and the EGR control is stopped (normal operation).

  FIG. 12 is a graph showing the drive timing of the intake and exhaust valves. The operation timing B (solid line) of the intake valve 33 and the operation timing A (one-dot chain line) of the exhaust valve 34 are respectively defined by an intake cam lobe 42i and an exhaust cam lobe 42e (see FIG. 4) formed on the steady cam member 42. Yes.

  Normally, at the valve timing of the intake / exhaust valves in a four-cycle engine, the intake / exhaust valves do not open at the same time except that an overlap period is provided in a predetermined range across the crank angle zero (exhaust top dead center). However, in the internal combustion engine 10 according to the embodiment, in order to perform EGR control in which a part of the exhaust gas is returned from the exhaust port into the combustion chamber and re-combusted, the electromagnetic solenoid 61 is excited to make the variable cam member 50 the exhaust rocker. By engaging with the arm 44e, the exhaust valve 34 can be opened while the intake valve 33 is open.

Specifically, as indicated by a broken line (C) in the figure, a relatively small valve is used during a valve opening period T (for example, a period of 90 degrees before and after straddling the crank angle of 180 degrees) from the intake stroke to the compression stroke. The EGR control is executed by opening the exhaust valve 34 with the lift amount. The beauty bar Ruburifuto amount Oyo valve timing in the EGR control is variably cam lobes 50e thus defined formed in a variable cam member 50.

  FIG. 13 is an EGR operation region map 101. While the EGR control is more effective in purifying exhaust gas when the internal combustion engine 10 is in a predetermined operating state, it is better to deactivate the EGR control in a state far away from the predetermined operating state. It has been known. In the EGR operation region map as the two-dimensional map, the EGR operation region is defined by the engine speed Ne and the throttle opening TH. The EGR operating region can be set, for example, in a region where the throttle opening TH is small (for example, opening 0 to 35%) and the engine speed is medium (for example, 2750 to 4500 rpm).

  In the present embodiment, an area in which the upper left in the figure is cut out in a triangular shape from a rectangle having the engine speed Ne in the range of Ne1 to Ne2 and the throttle opening TH in the range of 0 (zero) to TH2, is an EGR operating area. It is set as D (solid line). The reason for excluding a part of the rectangular area in this way is to increase the throttle opening TH for executing the EGR control linearly within the range of TH1 to TH2 within the range of Ne1 to Nea. According to human experiments, it was confirmed that the engine output and the exhaust gas purification performance were improved by deactivating EGR control in this triangular region.

  In the EGR operation region D, a hysteresis setting region E (two-dot chain line portion) applied when canceling EGR control is set. For example, when the engine speed Ne decreases from Ne3 while the throttle opening TH is THa, the EGR control is started by reaching the engine speed Ne2 that defines the EGR control region D. On the other hand, when the engine speed Ne increases toward Ne2 while the throttle opening TH remains THa, the EGR control is terminated by reaching Ne3 that defines the hysteresis setting region E larger than Ne2. Is set to Thereby, it is possible to prevent the excitation and demagnetization of the electromagnetic solenoid 61 from being repeated near the boundary of the EGR operation region D.

  As described above, the ECU 100 is configured to start the EGR control when the operating state of the internal combustion engine 10 enters the EGR operation region D, and conversely ends the EGR control when the operation state deviates from the EGR operation region D. However, if the electromagnetic solenoid 61 is actuated immediately after detecting that the EGR actuating region D has been entered or deviated from the EGR actuating region D, there is a possibility that a switching operation noise is generated in the variable valve timing mechanism 60.

  Specifically, when the EGR control is ended, the variable cam member 50 is slid to release the engagement state between the variable cam lobe 50e and the exhaust rocker arm 44e. At this time, the variable cam lobe 50e releases the exhaust valve. In the open state, when the variable cam lobe 50e is pulled out in the axial direction, the exhaust valve 34 closes vigorously by the biasing force of a valve spring (not shown) that biases the exhaust valve 34 in the closing direction. . As a result, a contact sound is generated when the umbrella portion (valve face) of the exhaust valve 34 and the valve contact portion (valve seat) provided in the exhaust port 15e abut against each other.

  Therefore, in the present embodiment, when the exhaust valve 34 is opened by the variable cam member 50 when the drive state of the exhaust valve 34 is detected based on the crank pulse and the Pb sensor output and the EGR control is to be ended. Then, after waiting until the exhaust valve 34 is fully closed, the electromagnetic solenoid 61 is demagnetized and the variable cam lobe 50e is slid. As a result, when the EGR control is terminated, it is possible to prevent the sound of the exhaust valve 34 from coming into contact with the valve seat. In this embodiment, even when the EGR control is started, if the exhaust valve 34 is open by the variable cam member 50 during the valve opening period T, the electromagnetic valve waits until the exhaust valve 34 is fully closed before electromagnetic The solenoid 61 is set to be excited.

  Further, in the internal combustion engine 10 according to the present embodiment, the ECU 100 that executes fuel injection control is configured to execute fuel cut control that stops fuel injection when decelerating at a predetermined vehicle speed or higher. This fuel cut control is set to stop fuel injection in a predetermined engine rotation region, for example, when the throttle opening TH is fully closed at a predetermined vehicle speed or higher.

  Here, assuming that the engine is decelerated by engine braking by throttle-off from a high-speed state, both the vehicle speed and the engine speed decrease as the elapsed time from throttle-off increases, but at a certain predetermined low-speed When the vehicle is decelerated to the region, it is necessary to restart fuel injection to avoid engine stall even when the throttle opening is fully closed. However, if normal injection is resumed when a certain engine speed is reached, the engine output may change and affect drivability. Therefore, in the present embodiment, when the injection control is returned from the fuel cut state at the time of deceleration, a change in engine output at the time of reinjection is performed by executing a fuel cut amount gradual decrease control that gradually decreases the fuel cut amount. Is set to be small.

  The present embodiment is characterized in that the engine speed at which fuel injection control is resumed from the fuel cut control is set lower than the minimum engine speed in the EGR operation region D. Specifically, referring to FIG. 13, the engine speed NeL (for example, 2000 rpm) for ending the fuel cut control when decelerating by throttle-off is based on the minimum engine speed Ne1 (for example, 2750 rpm) in the EGR operating region D. It is set to a low value. Further, the engine rotational speed NeH (for example, 2200 rpm) at which the fuel cut amount gradual decrease control is started is also set to a value lower than the minimum rotational speed Ne1 in the EGR operation region D.

  According to the setting as described above, it is possible to prevent straddling between the EGR operating region and the EGR non-operating region in a state where fuel injection is being executed during deceleration. For example, if the fuel injection is being performed during deceleration and the EGR non-operating region is switched to the EGR operating region, the combustion state becomes more favorable due to EGR control, and the engine output may change in a direction that improves. There is. Then, the engine output is improved during deceleration with the throttle off, which may affect drivability. On the other hand, according to the above-described setting, the fuel cut control in which fuel injection is not performed is performed over the EGR operation region D, and the operation non-operation of the EGR control is switched without affecting the engine output. It becomes possible.

  FIG. 14 is a flowchart showing a procedure of EGR cam drive solenoid control. In this flowchart, the control procedure of the EGR cam (variable cam member) 50 by the ECU 100 is shown. In step S1, the throttle opening TH is detected by the TH sensor 104, and in the subsequent step S2, the engine speed Ne is detected by the Ne sensor 102.

  In step S3, the search of the EGR operation region map 101 in the ECU 100 is executed. In step S4, it is determined whether the throttle opening TH is within a predetermined range. If an affirmative determination is made, the process proceeds to step S5, where it is determined whether the engine speed Ne is within the predetermined range. If an affirmative determination is made in step S5, the process proceeds to step S6, and it is determined whether or not the engine temperature Tw is equal to or higher than a predetermined value TwS. As described above, in the present embodiment, the engine temperature Tw is also taken into consideration in addition to the throttle opening degree TH and the engine speed Ne as the start condition of the EGR control.

  If an affirmative determination is made in step S6, it is determined that the EGR operation condition is satisfied, the process proceeds to step S7, and the EGR cam drive condition flag F = 1 is set. On the other hand, if a negative determination is made in any one of steps S4, 5, and 6, it is determined that the EGR operating condition is not satisfied, the process proceeds to step S8, and the EGR cam drive condition flag F = 0 is set.

  In step S9, based on the crank pulse and the Pb sensor output, it is determined whether or not the exhaust valve operating region is due to the variable cam member. This determination is to determine whether or not the current phase of the crankshaft 11 is in the region where the exhaust valve 34 is opened by the variable cam lobe 50e of the variable cam member 50, that is, in the valve opening period T.

  If an affirmative determination is made in step S9, that is, if the EGR control is being performed, if it is determined that the exhaust valve 34 is open by the variable cam member 50, the process proceeds to step S10 and the exhaust valve by the variable cam member is advanced. It is determined whether or not the operating region (valve opening period T) has been exceeded. If a negative determination is made in step S10, the process proceeds to step S11 to enter a standby state and returns to the determination in step S9.

  On the other hand, if an affirmative determination is made in step S10, that is, if the EGR control is being performed, the drive of the exhaust valve 34 by the variable cam member 50 is completed and the exhaust valve 34 is in a fully closed state (if the EGR control is not being performed, When it is determined that the valve is originally fully closed, the process proceeds to step S12.

In step S12, whether or not the EGR cam drive condition flag F = 1 set in step S 7 is determined. When an affirmative determination is made in step S12, the process proceeds to step S13, the electromagnetic solenoid 61 is switched on, EGR control is started, and a series of control is completed. On the other hand, if a negative determination is made in step S12, the process proceeds to step S14, where the electromagnetic solenoid 61 is switched off, the EGR control is terminated, and the series of controls is terminated.

  FIG. 15 is a flowchart showing a procedure of deceleration fuel cut control. The reference numerals and the like shown in this flowchart correspond to the descriptions in the EGR operation region map shown in FIG. In step S20, it is determined based on a fuel cut map (not shown) stored in the ECU 100 whether or not a fuel cut condition is satisfied. The parameters of the fuel cut condition can be, for example, the vehicle speed V, the engine speed Ne, and the throttle opening TH.

  In step S21, it is determined whether or not the fuel is being cut. In subsequent step S22, it is determined whether or not the throttle is fully closed. When an affirmative determination is made in steps S20, 21, and 22, the process proceeds to step S23, in which it is determined whether or not the engine speed Ne is equal to or higher than a high-side predetermined value NeH (for example, 2200 rpm). If an affirmative determination is made in step S23, the process proceeds to step S24, in which it is determined whether or not the engine temperature Tw is equal to or higher than a predetermined value TwL (for example, 40 degrees).

  If a negative determination is made in step S23, that is, if it is determined that the engine speed Ne is in a predetermined low rotation state, the process proceeds to step S25. Further, when a negative determination is made in step S24, that is, when it is determined that the engine temperature Tw is in a predetermined low temperature state, the process proceeds to step S25. On the other hand, when an affirmative determination is made in step S24, that is, when it is determined that the engine temperature Tw is in a predetermined high temperature state, the series of control is terminated as it is.

  In step S25, it is determined whether or not the engine speed Ne exceeds a low-side predetermined value NeL (for example, 2000 rpm). If an affirmative determination is made in step S25, the process proceeds to step S26, where fuel cut amount gradual reduction control is started, and in step S27, the fuel cut amount gradual decrease control counter is incremented. The fuel cut amount gradual decrease control counter can be provided in the ECU 100.

  In step S28, it is determined whether or not the fuel cut amount gradual decrease control counter has reached a predetermined value. If an affirmative determination is made, the process proceeds to step S29, where fuel cut control is terminated (fuel injection control is restored). If a negative determination is made, a series of control is terminated as it is. If a negative determination is made in step S25, the process proceeds to step S29 as it is to forcibly terminate the fuel cut control, and the series of controls is terminated. According to the fuel cut control as described above, by gradually reducing the fuel cut amount from the fuel cut control state, fluctuations in engine output at the time of fuel re-injection (at the time of fuel injection return) are suppressed, and drivability Can be improved.

  The structure of the variable valve timing mechanism, the setting of the EGR operation region map, the set value of the engine speed for ending the fuel cut control, etc. are not limited to the above embodiment, and various changes can be made. The exhaust gas recirculation control device for an internal combustion engine according to the present invention is not limited to a motorcycle, but can be applied to various vehicles such as a straddle-type three / four-wheel vehicle, a general-purpose engine, and the like.

  DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2m ... Main frame, 10 ... Internal combustion engine (engine), 33 ... Intake valve, 34 ... Exhaust valve, 40 ... Valve-operating mechanism, 41 ... Valve-operating cam shaft, 42 ... Steady cam member, 42i ... Intake Cam lobe, 42e ... exhaust cam lobe, 44i ... intake rocker arm, 44e ... exhaust rocker arm, 50 ... variable cam member, 50e ... variable cam lobe, 60 ... variable valve timing mechanism, 61 ... electromagnetic solenoid (actuator), 65 ... swing arm , 100 ... ECU (control device), 101 ... EGR operating region map, 102 ... Ne (engine speed) sensor, 103 ... Tw (engine temperature) sensor, 104 ... TH (throttle opening) sensor, 105 ... Pb sensor, D: EGR operating region, E: Hysteresis setting region, NeH: Fuel cut amount gradually decreasing control start Number, NeL ... fuel cut control termination engine rotation speed

Claims (12)

EGR control in which part of the exhaust gas is returned to the combustion chamber (15z) and recombusted by opening the exhaust valve (34) of the internal combustion engine (10) in a stroke other than the exhaust stroke in accordance with the operation of the actuator (61). In an exhaust gas recirculation control device for an internal combustion engine that executes
The switching of the EGR control operation / non-operation state is performed by operating the actuator (61) and the exhaust valve (34) based on the cam profile of the variable cam member (50) rotating synchronously with the valve drive cam shaft (41). ) And a state in which the operation of the exhaust valve (34) based on the cam profile of the cam member (50) is not performed.
A controller (100) for controlling the actuator (61) based on an EGR operation region map (101) having at least the engine speed (Ne) and the throttle opening (TH) as parameters;
The control unit (100) is configured to cut fuel injection by the fuel injection device when a fuel cut condition is satisfied, for example, when the vehicle (1) is decelerated,
The fuel cut condition is defined by a fuel cut map defined by at least the vehicle speed (V), the engine speed (Ne), and the throttle opening (TH), and the engine speed (Ne) is a low predetermined value. When it is below (NeL), it is set so that the fuel injection cut ends and the fuel injection returns.
The minimum value (Ne1) of the engine speed (Ne) constituting the EGR operating region (D) of the EGR operating region map (101) is set to a value higher than the low side predetermined value (NeL) of the fuel cut condition. Has been
A fuel cut that gradually reduces the fuel cut amount between a minimum value (Ne1) of the engine speed (Ne) that constitutes the EGR operating region (D) and a low value (NeL) of the fuel cut condition A high-side predetermined value (NeH) is set as the start timing of the amount gradual decrease control,
The difference between the high side predetermined value (NeH) and the minimum value (Ne1) is set larger than the difference between the low side predetermined value (NeL) and the high side predetermined value (NeH). exhaust gas recirculation control apparatus for an internal combustion engine, characterized in that there. When the operating state of the internal combustion engine (10) is in the EGR operating region (D) of the EGR operating region map (101), the control unit (100) sets the cam profile of the variable cam member (50). Based on this, the exhaust valve (34) is operated to perform EGR control, and the operating state of the internal combustion engine (10) is changed during the valve opening period (T) of the exhaust valve (34) by the variable cam member (50). When the EGR operating region (D) is deviated, the variable cam member (50) is kept waiting until the valve opening period (T) ends and the exhaust valve (34) is fully closed. The exhaust of the internal combustion engine according to claim 1, wherein the exhaust valve (34) based on a cam profile is switched to a state in which the operation of the exhaust valve (34) is not performed and the EGR control is switched to a non-operating state. Circulation control device. The actuator (61) slides on a variable cam member (50) that is slidable in the axial direction and not relatively rotatable with respect to the valve drive camshaft (41) that drives the exhaust valve (34). Configured to be possible,
Switching between the non-operating state of the EGR control is executed by sliding the variable cam member (50) by the actuator (61) to switch the non-engaging state with the exhaust valve (34). ,
The exhaust valve (34) is driven with the exhaust cam lobe (42e) fixed to the valve camshaft (41) and the exhaust rocker arm (44e) engaged when the EGR control is not operated. When the EGR control is activated, the variable cam member (50) and the exhaust cam lobe (42e) are both driven to be engaged with the exhaust rocker arm (44e). The exhaust gas recirculation control device for an internal combustion engine according to claim 1 or 2 . When the operating state of the internal combustion engine (10) is in the EGR operating region (D) of the EGR operating region map (101), the control unit (100) moves the variable cam member (50) to the exhaust rocker. The EGR control is performed by engaging the arm (44e), and the operating state of the internal combustion engine (10) is changed to the EGR operation during the valve opening period (T) of the exhaust valve (34) by the variable cam member (50). When the region (D) is deviated, the variable cam member (50) is disengaged after waiting until the valve opening period (T) ends and the exhaust valve (34) is fully closed. The exhaust gas recirculation control device for an internal combustion engine according to claim 2 or 3, wherein the EGR control is switched to a non-operating state as a state. The control unit (100) starts a counter with the start of the fuel cut amount gradual decrease control, and when the counter reaches a predetermined value, the fuel cut amount gradual decrease control and the fuel cut are finished and the fuel injection is resumed. The exhaust gas recirculation control device for an internal combustion engine according to any one of claims 1 to 4, wherein the exhaust gas recirculation control device is configured as described above. The controller (100) determines that the operating state of the internal combustion engine (10) is in the EGR operating region (D) during a period that is not the valve opening period (T) of the exhaust valve (34) by the variable cam member (50). The internal combustion engine according to any one of claims 2 to 4, wherein the variable cam member (50) is brought into a disengaged state without waiting when the engine is disengaged. Exhaust gas recirculation control device. The control unit (100) determines that the operating state of the internal combustion engine (10) is in the EGR operating region map (101) during the valve opening period (T) of the exhaust valve (34) by the variable cam member (50). When entering the EGR operation region (D), the variable cam member (50) is engaged after waiting until the valve opening period (T) ends and the exhaust valve (34) is fully closed. 7. The exhaust gas recirculation control device for an internal combustion engine according to claim 2, wherein the exhaust gas recirculation control device is configured to be in a combined state. Whether the exhaust valve (34) is in the valve opening period (T) by the variable cam member (50) is detected at least by crank pulse information of the internal combustion engine (10). An exhaust gas recirculation control device for an internal combustion engine according to any one of claims 1 to 7. The EGR operating region map (101) is defined by a two-dimensional map comprising an engine speed (Ne) and a throttle opening (TH).
The EGR operating region (D) is a rectangular shape formed by a predetermined range (Ne1 to Ne2) of the engine speed (Ne) and a predetermined range (0 to TH2) of the throttle opening (TH). The internal combustion engine exhaust according to any one of claims 1 to 8 , characterized in that it is formed by excluding a predetermined range of a substantially triangular shape having an engine speed (Ne) and a high throttle opening (TH). Recirculation control device. The exhaust gas recirculation control device for an internal combustion engine according to any one of claims 1 to 9 , wherein the fuel cut condition includes that the throttle opening (TH) is in a fully closed state . (Old claim 8)
Wherein the EGR operation region map (101) to any one of claims 1 to 10, characterized in that the hysteresis setting area for providing a hysteresis characteristic to the EGR operation region (D) (E) is provided An exhaust gas recirculation control device for an internal combustion engine as described. A plunger (61p) as an operating shaft of the actuator (61) is disposed in parallel with the valve cam shaft (41),
The variable cam member (50) is always urged by a coil spring (56) in a direction in which it is disengaged from the exhaust valve (),
The sliding movement of the plunger (61p) is a swing arm that is pivotally supported by a pivot bolt (64) oriented in a direction perpendicular to the plunger (61p) and the valve camshaft (41). (65) is configured to be transmitted to the variable cam member (50),
When the actuator (61) is excited, the variable cam member (50) slides against the urging force of the coil spring (56), and the variable cam member (50) and the exhaust rocker arm ( 44e) is in an engaged state, and on the other hand, when the actuator (61) is demagnetized, both are returned to a non-engaged state by the biasing force of the coil spring (56). An exhaust gas recirculation control device for an internal combustion engine according to any one of claims 1 to 11 .