CN102787923B - The exhaust gas recirculatioon controller of internal combustion engine - Google Patents

Abstract

The invention relates to an exhaust gas recirculation controller of an internal combustion engine. The exhaust gas recirculation controller of the internal combustion engine includes using the engine speed (Ne) and the throttle opening (TH) as parameters to cut off the fuel injection to control according to the EGR operating range map during the deceleration of the motorcycle when the fuel cut condition is met On or off the control part of the actuator EGR control. The fuel cut condition is determined by a fuel cut map determined by vehicle speed (V), engine speed (Ne) and throttle opening (TH), and is set such that if the engine speed (Ne) is below a lower specified value (NeL) , the fuel injection cutoff is terminated, and fuel injection is resumed. The lowest value (Ne1) of the engine speed (Ne) constituting the EGR operation range (D) of the EGR operation range map is set to a value higher than the lower specified value (NeL) of the fuel cut condition. In addition, EGR does not generate operating noise at the start and end of ERG control operation.

Description

Exhaust gas recirculation controller for internal combustion engines

technical field

This invention relates to exhaust gas recirculation controls for internal combustion engines, and more particularly to exhaust gas recirculation controls for internal combustion engines that return some of the exhaust gas to the combustion chamber for reburning with intake gas.

Background technique

In known exhaust gas recirculation (EGR) systems, some of the exhaust gas from the internal combustion engine is rebreathed on the inlet side so that the exhaust gas is recombusted in order to improve exhaust gas purification and fuel economy. Also, in an internal combustion engine having a fuel injection system, so-called fuel cut control may be performed to stop fuel injection during deceleration or the like where the throttle device is completely closed at a prescribed vehicle speed and above.

JP-A No. 2004-108329 discloses an internal combustion engine using an EGR system that returns some exhaust gas from an intake port to a combustion chamber via a bypass path that communicates the intake port and the exhaust port. A learning process is required to adjust the standard opening of the EGR valve to open or close the bypass path according to aging degradation such as impurity attachment while performing fuel cut control.

But in the technique described in JP-A No. 2004-108329, since the EGR valve opening learning process is executed during the fuel cut control, the EGR control is considered to be always performed during the fuel cut and after the end of the fuel cut control, and the EGR control is off. This means that the combustion conditions of the internal combustion engine change due to the switch-off of the EGR control, which changes the torque produced by the internal combustion engine. More particularly, in many cases, after a fuel cut, the throttle opening is small and the engine torque is small, and the driver will easily feel some change in torque when the EGR control is turned off.

In known exhaust gas recirculation (EGR) systems, some of the exhaust gas from the internal combustion engine is rebreathed on the inlet side in order to burn it again, thereby purifying the exhaust gas and improving fuel economy. EGR systems are broadly classified as external EGR in which a bypass path communicating the intake port with the exhaust port is used to return some exhaust gas from the intake port to the combustion chamber and in which the exhaust valve opens slightly during the intake stroke to An internal EGR type that returns some exhaust gas from the exhaust port to the combustion chamber.

Japanese Patent Publication No. 4555771 discloses an EGR system of the internal EGR type in which the rocker arm of the exhaust valve is compressed by a solenoid to open the exhaust valve at the desired timing during the intake stroke regardless of the cam The angle of rotation of the axis.

However, the technique described in Japanese Patent Laid-Open Document No. 4555771 has a problem in that the solenoid must be energized every intake stroke to open the exhaust valve while EGR control is being performed. Therefore, it is difficult to perform operation control of the exhaust valve in the high speed range of the internal combustion engine.

On the other hand, a possible configuration for EGR control by actuation of the exhaust valve is to provide an EGR cam to determine the timing of actuating the exhaust valve for EGR control. In EGR control, not only the cam for normal operation but also the EGR cam needs to be engaged to actuate the exhaust valve. In this configuration, there is a problem of noise when switching the two cams when precise control of the exhaust valve is desired in the high-speed range.

Contents of the invention

An object of an embodiment of the present invention is to provide an exhaust gas recirculation controller for an internal combustion engine, which solves the above-mentioned problems of the conventional technology, and does not make the driver feel the turning on and off when the fuel cut control and the EGR control are turned on and off. moment change.

In order to achieve the above object, according to an embodiment of the present invention, there is provided an exhaust gas recirculation controller of an internal combustion engine for performing EGR control so as to turn on the EGR of the internal combustion engine by operating an actuator in a stroke other than the exhaust stroke. Exhaust valves to return some of the exhaust gas to the combustion chamber and allow it to burn again. EGR is controlled by operating the actuator so that in a state where the exhaust valve is actuated according to a cam profile of a variable cam member that rotates in synchronization with a valve operating camshaft and the exhaust valve is actuated according to the cam profile of the cam member Toggle between states without actuation to switch on or off. The control portion is configured to use at least the engine speed Ne and the throttle opening TH as parameters to control the actuator according to the EGR operating range map. The control section cuts off fuel injection of the fuel injection system during vehicle deceleration or the like when a fuel cut condition is satisfied. The fuel cut condition is determined by a fuel cut map determined by the vehicle speed V, the engine speed Ne, and the throttle opening TH, and is set to end the fuel injection cut if the engine speed Ne is below a lower prescribed value NeL , and fuel injection is performed again, and the lowest value Ne1 of the engine speed Ne constituting the EGR operation range D of the EGR operation range map is set to a value higher than the lower prescribed value NeL of the fuel cut condition.

According to an embodiment of the present invention, the actuator is capable of sliding a variable cam member attached to the valve operating camshaft to operate the exhaust valve in an axially slidable manner without relative rotation. The EGR control is turned on or off by an actuator that slides the variable cam member into and out of engagement with the exhaust valve. When the EGR control is off, the exhaust valve is operated by an exhaust cam lobe fixed to the valve operating camshaft and engaged with an exhaust rocker arm. When the EGR control is on, the exhaust valve is operated by both the variable cam member and an exhaust cam lobe engaged with the exhaust rocker arm.

According to the embodiment of the present invention, the higher prescribed value NeH as the timing of starting the fuel cut speed gradual reduction control to gradually decrease the fuel cut speed is set at the lowest value Ne1 of the engine speed Ne constituting the EGR operation range D and the lower specified value NeL of the fuel cut condition.

According to an embodiment of the invention, the difference between said upper defined value NeH and said lowest value Ne1 is greater than the difference between said lower defined value NeL and said upper defined value NeH.

According to an embodiment of the present invention, the control section starts a counter when starting the fuel cut speed gradual reduction control, and when the counter reaches a prescribed value, the control section ends the fuel cut speed gradual reduction control and fuel cutoff speed for re-injection.

According to an embodiment of the present invention, said EGR operating range map is defined by a 2D map comprising said engine speed Ne and throttle opening TH, and said EGR operating range D is defined by having a low engine speed Ne and a high throttle opening TH. An almost triangular prescribed range of device opening TH is formed excluding from a rectangle in which the engine speed Ne is within the prescribed range Ne1-Ne2 and the throttle opening TH is within the prescribed range 0-TH2.

According to an embodiment of the present invention, the fuel cut condition includes that the throttle opening TH is in a fully closed position.

According to an embodiment of the present invention, the EGR operating range map includes a hysteresis setting range E for setting a hysteresis characteristic for the EGR operating range D.

According to an embodiment of the present invention, the actuator is capable of sliding the variable cam member attached to the valve operating camshaft to operate the exhaust valve axially slidable without relative rotation. EGR control is turned on or off by an actuator sliding a variable cam member into engagement or disengagement with an exhaust valve. With EGR control off, the exhaust valves are operated by exhaust cam lobes fixed to the valve operating camshaft and engaged with exhaust rocker arms. When EGR control is on, the exhaust valve is operated by both the variable cam member and the exhaust cam lobe engaged with the exhaust rocker arm, and the control is configured to use at least engine speed and throttle opening as parameters to control the actuators according to the EGR operating range map. The control section cuts off fuel injection of the fuel injection system during vehicle deceleration etc. when a fuel cut condition is satisfied, and the fuel cut condition is determined by a fuel cut map determined by vehicle speed, engine speed, and throttle opening. If the engine speed is below the lower specified value, the fuel injection cut is terminated, and the fuel injection is restarted, and the lowest value of the engine speed constituting the EGR operating range of the EGR operating range map is set to a lower specified value than the fuel cut condition A high value prevents switching between the EGR operating range and the EGR non-operating range while fuel injection occurs during deceleration.

For example, if fuel injection is performed during deceleration while switching from an EGR non-operating range to an EGR operating range, combustion conditions may become better due to EGR control, resulting in improved engine output. This improves engine output during deceleration with the throttle closed (which affects drivability). On the other hand, with the arrangement according to the present invention, switching of the EGR operation range is performed during fuel cut control without fuel injection, which means that EGR control can be turned on and off without affecting engine output.

According to the embodiment of the present invention, a higher prescribed value of the timing to gradually decrease the fuel cut speed as starting the fuel cut speed gradual reduction control is set at a lower value of the engine speed constituting the EGR operation range and the lower value of the fuel cut condition. Between the low predetermined value, the fuel cut speed is gradually decreased from the fuel cut control state, thereby suppressing the change of the engine output when the fuel is re-injected (re-injecting the fuel), so that the drivability is improved.

According to the embodiment of the present invention, since the difference between the upper prescribed value and the lowest value is greater than the difference between the lower prescribed value and the upper prescribed value, the period from the start of the fuel cut speed gradual reduction control to its end can be shortened. , thereby reducing fuel consumption during this cycle.

According to the embodiment of the present invention, since the control section starts the counter when starting the fuel cut speed gradual reduction control, and when the counter reaches a prescribed value, the control section ends the fuel cut speed gradual reduction control and the fuel cut speed to restart the fuel cut speed. Injection, the period from the start of the fuel cut speed gradual reduction control to its end can be freely changed by changing the condition of the increment counter or the prescribed value setting. Therefore, even if the type of internal combustion engine and the like are different, the fuel cut speed gradual reduction control can be smoothly performed.

According to an embodiment of the invention, the EGR operating range map is defined by a 2D map comprising engine speed and throttle opening, and the EGR operating range is defined by dividing an almost triangular prescribed range with low engine speed and high throttle opening from The engine speed is within the specified range and the throttle device opening is excluded from the rectangle within the specified range, so that the improvement of the engine output and the improvement of the exhaust gas purification effect can be realized by turning off the EGR control within the specified range of the triangle in the 2D map .

According to the embodiment of the present invention, since the fuel cut condition includes the throttle opening being fully closed, the fuel cut control may be performed after the driver's intention to reduce the speed is confirmed based on the throttle opening.

According to the embodiment of the present invention, since the EGR operating range map includes a hysteresis setting range for setting a hysteresis characteristic for the EGR operating range, repeated magnetization and demagnetization of the electromagnetic solenoid near the boundary of the EGR operating range can be prevented.

An object of embodiments of the present invention is to provide an exhaust gas recirculation controller of an internal combustion engine which solves the problems of the conventional art, does not generate operation noise at the start and end of EGR control, and activates the exhaust gas at the correct timing. Gas valve for EGR control.

According to an embodiment of the present invention, there is provided an exhaust gas recirculation controller of an internal combustion engine for performing EGR control so as to open an exhaust valve of the internal combustion engine by an operation of an actuator in a stroke other than an exhaust stroke , returning some of the exhaust gas to the combustion chamber and allowing it to burn again. EGR is controlled by operating the actuator so that in a state where the exhaust valve is actuated according to a cam profile of a variable cam member that rotates in synchronization with a valve operating camshaft and the exhaust valve is actuated according to the cam profile of the cam member Toggle between states without actuation to switch on and off. The control portion is configured to use at least the engine speed Ne and the throttle opening TH as parameters to control the actuator according to the EGR operating range map. When the operating condition of the internal combustion engine is within the EGR operating range D of the EGR operating range map, the control portion actuates the exhaust valve 34 according to the cam profile of the variable cam member for EGR control, and When the operating condition of the internal combustion engine is outside the EGR operating range D during the period T in which the variable cam member opens the exhaust valve, the control portion waits until the valve opening period T ends, and the exhaust valve is fully closed, then the EGR control is turned off by transitioning to a state where actuation of the exhaust valve is not performed according to the cam profile of the variable cam member.

According to an embodiment of the present invention, the actuator is capable of sliding a variable cam member attached to the valve operating camshaft to operate the exhaust valve in an axially slidable manner without relative rotation, so The EGR control is turned on or off by the actuator sliding the variable cam member into and out of engagement with the exhaust valve. When the EGR control is off, the exhaust valve is operated by an exhaust cam lobe fixed to the valve operating camshaft and engaged with an exhaust rocker arm. When the EGR control is on, the exhaust valve is operated by both the variable cam member and an exhaust cam lobe engaged with the exhaust rocker arm. In addition, the control portion engages the variable cam member with the exhaust rocker arm to perform EGR control when the operating condition of the internal combustion engine is within the EGR operating range D of the EGR operating range map. Also, when the operating condition of the internal combustion engine is outside the EGR operating range D during the period T in which the variable cam member opens the exhaust valve, the control portion waits until the valve opens Period T ends and the exhaust valve is fully closed, then the EGR control is turned off by disengaging the variable cam member.

According to an embodiment of the present invention, when the operating condition of the internal combustion engine is outside the EGR operating range D and at the same time not within the period T in which the variable cam member opens the exhaust valve, the control portion causes the The variable cam member is disengaged without waiting.

According to an embodiment of the present invention, when the operating condition of the internal combustion engine enters the EGR operating range D of the EGR operating range map during the period T in which the variable cam member opens the exhaust valve, the control Partially wait until the valve opening period T is complete and the exhaust valve is fully closed before engaging the variable cam member.

According to an embodiment of the present invention, whether the operating condition of the internal combustion engine is detected by at least crank pulse data of the internal combustion engine within a period T in which the variable cam member opens the exhaust valve.

According to an embodiment of the present invention, the EGR operating range map includes a hysteresis setting range E for setting a hysteresis characteristic for the EGR operating range D.

According to an embodiment of the present invention, said EGR operating range map is defined by a 2D map comprising said engine speed Ne and throttle opening TH, and said EGR operating range D is defined by having a low engine speed Ne and a high throttle opening TH. An almost triangular prescribed range of device opening TH is constituted excluding a rectangle in which said engine speed Ne is within a prescribed range Nei-Net and said throttle opening TH is located within a prescribed range 0-TH2.

According to an embodiment of the present invention, the plunger, which is the operating shaft of the actuator, is positioned parallel to the valve operating camshaft, and the variable cam member is directed toward disengagement from the exhaust valve by a coil spring. constant bias. Sliding motion of the plunger is transmitted to the variable cam member via a swing arm that is swingably journalled by a pivot bolt oriented vertically relative to the plunger and the valve operating camshaft. When the actuator is magnetized, the variable cam member slides against the biasing force of the coil spring and engages the exhaust rocker arm. On the other hand, when the actuator is demagnetized, the two are disengaged again by the biasing force of the coil spring.

According to an embodiment of the present invention, the actuator is capable of sliding the variable cam member attached to the valve operating camshaft to operate the exhaust valve axially slidably without relative rotation, and the EGR is controlled by the actuator Sliding the variable cam member into engagement or disengagement with the exhaust valve turns it on or off. With EGR control off, the exhaust valves are operated by exhaust cam lobes fixed to the valve operating camshaft and engaged with exhaust rocker arms. When EGR control is on, the exhaust valve is operated by both a variable cam member and an exhaust cam lobe engaged with an exhaust rocker arm. The control portion is configured to control the actuator according to the EGR operating range map using at least the engine speed and the throttle opening as parameters, wherein the control portion causes The variable cam member is engaged with the exhaust rocker arm to perform EGR control, and when the operating condition of the internal combustion engine is outside the EGR operating range during the period in which the variable cam member opens the exhaust valve, the control portion waits until The valve opening period ends, and the exhaust valve is fully closed, then EGR control is shut off by disengaging the variable cam member so that the exhaust valve timing in EGR control is passed such that the variable cam member engages the exhaust rocker arm Engagement is determined, and the operation control of the exhaust valve cannot become complicated as the engine speed increases as in the method in which the exhaust valve is directly opened by the solenoid driving force. Also, with the EGR control turned off, there is no possibility of making contact with the cylinder sound due to sudden closing of the valve spring biased exhaust valve when the exhaust valve is held open by the variable cam member and even if not within the EGR operating range , because the variable cam member does not operate until the exhaust valve is closed. In other words, it is possible to obtain an exhaust gas recirculation controller that can mechanically determine the timing of the EGR valve without generating a contact sound when the EGR control is turned on and off.

According to the embodiment of the present invention, when the operating condition of the internal combustion engine is outside the EGR operating range and not within the period in which the variable cam member opens the exhaust valve, the control portion disengages the variable cam member without waiting, thereby even at During EGR control, when the exhaust valve is fully closed, there is no possibility of generating a contact sound, so by disengaging the variable cam member, the transition to the EGR off state can be achieved quickly.

According to an embodiment of the present invention, during a period in which the variable cam member opens the exhaust valve, when the operating condition of the internal combustion engine enters the EGR operating range of the EGR operating range map, the control portion waits until the valve opening period ends, and the exhaust valve is fully closed, which in turn engages the variable cam member, so that the exhaust cam member is unlikely to slip during the cycle in which the variable cam member opens the exhaust valve, thereby allowing smooth transition control.

Further scope of applicability of the present invention will become apparent from the detailed description given subsequently. It should be understood, however, that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are given by way of illustration only, since the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. various changes and modifications.

Description of drawings

The invention will be more fully understood from the detailed description given below and the accompanying drawings, which are given by way of example only and therefore do not limit the invention, in which:

1 is a left side view of a motorcycle employing an exhaust gas recirculation controller for an internal combustion engine according to an embodiment of the present invention;

Figure 2 is an enlarged side view of the internal combustion engine;

Fig. 3 is a partially enlarged cross-sectional view of the internal combustion engine seen from the right side of the vehicle;

Fig. 4 is a partially enlarged cross-sectional view of the internal combustion engine seen from the rear of the vehicle;

Fig. 5 is a sectional view taken along line V-V of Fig. 4;

Figure 6 is an exploded perspective view of a valve operating camshaft, steady state cam member and variable cam member;

7 is a cross-sectional view of the valve operating camshaft, steady state cam member, and variable cam member when assembled;

Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7;

Figure 9 is a perspective view of a swing arm;

Figure 10 is a top view of the cylinder head;

11 is a block diagram showing the configuration of an exhaust gas recirculation controller of an internal combustion engine according to an embodiment of the present invention;

Figure 12 is a graph showing the timing of actuating the intake and exhaust valves;

FIG. 13 is a data map for determining the range in which EGR control is performed;

14 is a flowchart showing the sequence of EGR cam operation solenoid control; and

FIG. 15 is a flowchart showing the procedure of fuel cut control during deceleration.

detailed description

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a left side view of a motorcycle 1 employing an exhaust gas recirculation controller for an internal combustion engine according to an embodiment of the present invention. FIG. 2 is an enlarged side view of the internal combustion engine 10 . An internal combustion engine 10 (four-stroke single-cylinder gasoline engine) is mounted to the main body frame 2 of the motorcycle 1 with its crankshaft 11 oriented in the vehicle transverse direction.

The main body frame 2 includes a head pipe 2h, a pair of left and right main frames 2m extending downward from the head pipe 2h toward the rear of the vehicle, and a steep slope portion 2ma bent downward from the rear end of the main frame 2m. A single lower frame 2d extending steeply rearward and downward from the head pipe 2h is positioned almost parallel to the steeply inclined portion 2ma of the main frame 2m.

A pair of left and right seat rails 2s extends rearwardly from above the steeply inclined portion 2ma past the gusset 2g. The seat rail 2s is supported from below by the rear support 2b connected to the lower portion of the steeply inclined portion 2ma.

A pair of left and right front forks 3 are swingably supported by a head pipe 2h, and a front wheel Fw is rotatably journaled to its lower end. The swing arm 4 to which the rear wheel Rw is rotatably journaled is swingably journaled to the lower portion of the steeply inclined portion 2ma, and the rear bumper 5 is located between the swing arm 4 and the gusset 2g. A fuel tank 6 is mounted on the main frame 2m in a manner spanning from above, and a seat 7 supported by a seat rail 2s is arranged behind the fuel tank 6 .

The internal combustion engine 100 suspended by the main frame 2m and the lower frame 2d is an SOHC type engine integrated with a transmission in which the cylinder block 14, the cylinder head 15 and the top cover 20 are arranged in a slightly forward-inclined manner. At the rear of the cylinder head 15 , an air cleaner box 8 a is attached via a suction pipe 8 with a throttle valve installed therein. On the other hand, at the front of the cylinder head 15, the exhaust pipe 9 connected to the muffler 9m at the rear of the vehicle body is attached.

The internal combustion engine 10 according to this embodiment has an exhaust gas recirculation device (EGR system) that opens an exhaust valve at a desired timing during an intake stroke in order to return some exhaust gas to the combustion chamber and cause it to burn again. More specifically, the camshaft for actuating the exhaust valves has a cam lobe for normal operation and a cam lobe for EGR control such that the exhaust valve for EGR control that is not performed during normal operation Operation is performed by arbitrary actuation of a cam lobe for EGR control. As an actuator that actuates a cam lobe for EGR control, an electromagnetic solenoid 61 is attached to the head cover 20 of the internal combustion engine 10 .

Referring to FIG. 2, in the crankcase 13 in which the crankshaft 11 is journalled, a transmission chamber 13M for accommodating a transmission is formed at the rear of a crank chamber 13C in which the crankshaft 11 is positioned, and the output shaft 12 of the transmission is driven from the rear thereof. The portion protrudes in the left direction in the vehicle transverse direction. An oil tank 13P storing oil is integrally formed below the crank chamber 13C.

In addition, refer to FIG. 3 as well. FIG. 3 is a partially enlarged cross-sectional view of the internal combustion engine 10 seen from the right side of the vehicle. The crankcase 13 in which the crank chamber 13C, the transmission chamber 13M, and the oil sump 13P are formed is divided into a left side portion and a right side portion in the vehicle transverse direction. A cylinder head 15 including a cylinder block 14 with a sleeve 14a inserted therein and a valve train 40 is placed above the crank chamber 13C.

The camshaft holder 16 , the cylinder head 15 and the cylinder block 14 are fixed integrally with the crankcase 13 by head bolts 17 . The top cover 20 is placed over the cylinder head 15 via the elastic sealing member 18 . A piston 31 is reciprocally and slidably installed in the sleeve 14a of the cylinder 14, and the piston 31 and the crankshaft 11 are connected by a connecting rod 32 so as to constitute a crank mechanism.

In the cylinder head 15, a combustion chamber 15z is formed by facing the piston 31 in the cylinder axial direction, while an intake port 15i extends from the combustion chamber 15z toward the rear of the vehicle, and an exhaust port 15e extends from the combustion chamber 15z toward the vehicle Front extension.

The intake valve 33 and the exhaust valve 34 are swingably supported by valve guides respectively integrally mounted to the cylinder head 15 . As the intake valve 33 and the exhaust valve 34 are actuated by the valve train 40, they are synchronized with the rotation of the crankshaft 11, thereby opening and closing the intake opening of the intake port 15i and the exhaust opening of the exhaust port 15e.

FIG. 4 is a partially enlarged cross-sectional view of the internal combustion engine 10 seen from the rear of the vehicle. A spark plug 19 is installed in the cylinder head 15 with its tip inserted through the top side of the combustion chamber 15z. The valve train 40 is actuated by a single valve-operating camshaft 41 journalled in the vehicle transverse direction by the camshaft holder 16 .

Within the camshaft holder 16, rocker arm shafts 43e and 43i are supported on the valve operating camshaft 41 at front and rear positions. While the intake rocker arm 44i is pivotably journalled to the rear rocker arm shaft 43i, the exhaust rocker arm 44e is pivotally journalled to the front rocker arm shaft 43e.

A cylindrical steady-state cam member 42 having an intake cam lobe 42 i and an exhaust cam lobe 42 e formed side by side on its circumferential surface is press-fitted within the valve operating camshaft 41 . The driven cam sprocket 36 is fixed at the left end of the valve operating camshaft 41 in the vehicle transverse direction.

A driving cam sprocket 35 is fixed to the crankshaft 11, and an endless cam chain 37 bridges between the driving cam sprocket 35 and the driven cam sprocket 36 (see FIG. 2). At half (1/2) of the rotational speed of the crankshaft 11 , the rotational power of the crankshaft 11 is transmitted to the valve operating camshaft 41 . Therefore, the intake rocker arm 44i and the exhaust rocker arm 44e oscillate synchronously with the crankshaft 11, and the intake valve 33 and the exhaust valve 34 are opened and closed at appropriate timing.

On the left side of the cylinder block 14, the cylinder head 15, and the roof 20 in the vehicle transverse direction, the cam chain chambers 14c, 15c, and 20c form a single continuous chamber. As for the cam chain 37, in the cam chain chambers 14c, 15c, and 20c, its front portion is guided by a vertically and linearly extending chain guide 38, and its rear portion is held by an arc-shaped curved tension slider 39, thereby maintaining sufficient tension. The rear portion of the tension slider 39 is pressed by the tension lifter 39t.

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4 . FIG. 6 is an exploded perspective view of the valve operating camshaft 41 , the steady state cam member 42 and the variable cam member 50 . The same reference numerals as above denote the same or equivalent elements. The valve operating camshaft 41 is a cylindrical member having a central axis hole 41h and manufactured with high precision by cold forging.

A spline forming portion 41 c having a maximum outer diameter of six spline grooves 41 cs is formed at the axial center of the valve operating camshaft 41 . A cam holder 41r having a reduced diameter passing through the shoulder is formed on the right side of the spline forming portion 41c in the vehicle transverse direction, and a journal portion 41j having a further reduced diameter is formed at the right end thereof. A left cylindrical portion 411 also having a slightly reduced diameter is formed on the left side of the spline forming portion 41c. Elongated holes 41s of the same shape, which are elongated in the axial direction, are respectively formed in the two spline grooves 41cs positioned diagonally. A key groove 41 k is formed at the left end of the valve operating camshaft 41 .

A steady-state cam member 42 having an exhaust cam lobe 42e and an intake cam lobe 42i is press-fitted and fixed on the cam holder 41r at a prescribed relative angle. The steady-state cam member 42 is press-fitted with the exhaust cam lobe 42e on the left side in the vehicle transverse direction from the right side of the cam holder 41r until it contacts the spline forming portion 41c. Accordingly, the exhaust cam lobe 42e is integrally formed with the valve operating camshaft 41 adjacent to the spline forming portion 41c.

On the other hand, as an EGR cam that opens the exhaust valve 34 during the intake stroke to perform EGR control, the variable cam member 50 is spline-mounted to the spline-shaped portion 41c of the valve operating camshaft 41 . Six spline protruding channels 50 cs fitted into spline groove channels 41 cs formed in the valve operating camshaft 41 are formed on the inner peripheral surface of the variable cam member 50 . 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 transverse direction.

Most of the outer circumference of the variable cam lobe 50e forms a base circle having a diameter equal to or slightly smaller than that of the exhaust cam lobe 42e, and a cam nose protruding at a prescribed phase angle with a small boost amount for EGR control. On the other hand, in the cylindrical portion where the variable cam lobe 50e is not formed, there is a pin hole 50p perpendicular to the center axis through the spline projecting groove 50cs formed on the inner circumference of the variable cam member 50. . Also, an outer peripheral groove 50v passing through the outer opening of the pin hole 50p is formed in the outer peripheral surface of the cylindrical portion.

When the variable cam member 50 is spline-mounted to the spline-shaped portion 41c of the valve operating camshaft 41 at a prescribed relative angle from the left side in the vehicle transverse direction, the pin hole 50p of the variable cam member 50 is in contact with the valve operating camshaft 41. The elongated holes 41s coincide.

FIG. 7 is a cross-sectional view of the valve operating camshaft 41 , the steady state cam member 42 and the variable cam member 50 when assembled. FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 7 . The valve operating camshaft 41 is rotatably journalled relative to the camshaft holder 16 by a bearing 46 mounted to the journal portion 41j at its right end and a bearing 45 mounted to the left cylindrical portion 411 at its left end (see Figure 4). By press-fitting the flange member 47 to the left cylindrical portion 411 via the key 49 at a prescribed relative angle, the bearing 45 is held by the spline forming portion 41c.

A radially protruding flange portion 47f is formed at the left end of the flange member 47 shown in the drawing. The drive cam sprocket 36 is attached to the flange member 47 by screwing a screw 48 into a screw hole 36h and a screw hole 47h made in the flange portion 47f. The left end of the valve operating camshaft 41 engages the center hole 36 c of the drive cam sprocket 36 .

A slide rod 53 constituting a sliding mechanism 52 for sliding and displacing the variable cam member 50 is inserted into the central axis hole 41 h of the valve operating camshaft 41 slidable in the axial direction. The slide rod 53 has a slightly reduced diameter at both sides of its central large-diameter portion 53c, and has pin holes 53p made perpendicular to the central large-diameter portion 53c in the axial direction.

By inserting the slide rod 53 into the center axis hole 41h of the valve operating camshaft 41, then aligning the pin hole 53p with the elongated hole 41s of the valve operating camshaft 41 and the pin hole 50p of the variable cam member 50, and connecting the single The pin 54 is inserted between the aligned pin hole 50p, the elongated hole 41s and the pin hole 53p to assemble the slide mechanism 52 .

The coupling pin 54 is 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 the retaining ring 55 fitted into the outer peripheral groove 50v. Accordingly, the coupling pin 54 engages the pin hole 50 p of the variable cam member 50 at both ends thereof, and moves integrally with the variable cam member 50 . Therefore, as the slide rod 53 slides left and right in the axial direction within the central axis hole 41 h, the coupling pin 54 moves guided through the elongated hole 41 s, and the variable cam member 50 moves axially integrally with the coupling pin 54 .

In the central axis hole 41h of the valve operating camshaft 41, a female thread is formed in the inner peripheral surface at the right end thereof. The coil spring 56 is inserted into the central axis hole 41h from the right side, and then the flanged bolt 57 is screwed. Therefore, the coil spring 56 is located between the central large-diameter portion 53c of the slide rod 53 and the flanged bolt 57, constituting the slide mechanism 52 in which the slide rod 53 is constantly biased to the left.

The valve operating camshaft 41 in a semi-assembled form in which the steady state cam member 42, the variable cam member 50, the driven cam sprocket 36 and the bearings 45 and 46 are attached to its outer periphery is inserted in the camshaft from the left side in the vehicle transverse direction. In the axial holes of the left and right support walls 16 (16L and 16R, see FIG. 4 ) protruding opposite each other on the left and right sides of the holder 16 . Next, the valve operating camshaft 41 is rotatably journalled to the camshaft holder by fitting the right side bearing 46 into the axial hole of the right support wall 16R and fitting the left side bearing 45 into the axial hole of the left support wall 16L. Member 16 rotates integrally with the steady state cam member 42 and the variable cam member 50 .

The right side bearing 46 is positioned to abut on the shoulder of the right support wall 16R, and the left side bearing 45 is positioned by a retaining plate 59 fixed to the left support wall 16L by bolts 58 (see FIG. 4 ).

Referring to FIG. 4, since the slide lever 53 biased to the left by the coil spring 56 is pushed to the right against the biasing force of the coil spring 56, the variable cam member 50 slides to the right via the coupling pin 54, as shown in the figure. line shown. Therefore, the variable cam member 50 is closer to the exhaust cam lobe 42e, and the roller 44er of the exhaust rocker arm 44e contacts the exhaust cam lobe 42e and the variable cam lobe 50e across them. Therefore, regardless of the normal timing when the exhaust valve 34 is opened and closed by the exhaust cam lobe 42e, the exhaust valve 34 can be opened and closed to perform EGR (Exhaust Gas Recirculation). The roller 44ir (see FIG. 3 ) of the suction rocker arm 44i is designed to only contact the suction cam lobe 42i.

On the other hand, as the slide lever 43 is moved to the left by the coil spring 56, as shown by the two-dot dash line in FIG. 4, the variable cam member 50 slides in the left direction, and the roller of the exhaust rocker arm 44e 44er and variable cam lobe 50e do not contact each other. Thus, the exhaust valve 34 is opened and closed by the exhaust cam lobe 42e at normal timing for an exhaust valve.

A variable valve timing drive mechanism 60 that pushes the slide lever 53 to the right is provided on the left side of the driven cam sprocket 36 in the vehicle transverse direction. The variable valve timing driving mechanism 60 includes an electromagnetic solenoid 61 as an actuator and a swing arm 65 that transmits driving power of the electromagnetic solenoid 61 to the slide mechanism 52 . The electromagnetic solenoid 61 is fixed above the top wall 20 u of the top cover 20 , and the swing arm 65 is pivotally journalled in the cam chain chamber 20 c of the top cover 20 .

The top cover 20 is actually formed in a rectangular bowl shape having a top wall 20u and a peripheral wall 20s. The top wall 20u has a recessed portion 20uh for accommodating the cylindrical electromagnetic solenoid 61 and protrusions 20up adjacent to the recessed portion 20uh on the front and rear sides in the vehicle longitudinal direction (see FIGS. 3 and 4 ). The upwardly extending central protrusion 21 is formed in such a manner as to cover the electromagnetic coil 61 on the left side of the roof 20 in the vehicle transverse direction, and protrusions 22 are formed on the front and rear sides of the central protrusion 21 in the vehicle longitudinal direction. on the side (see Figure 5).

A central cavity 21 c having a sufficient width for insertion of the swing arm 65 is formed in the central projecting portion 21 . In the center projecting portion 21, a circular hole 21h oriented on the axis of the electromagnetic solenoid 61 in the vehicle transverse direction is formed in such a way as to reach the center chamber 21c. A mounting cylinder 62b fitted with the circular hole 21h is provided on one end face of the electromagnetic solenoid 61, and a plunger 61p as an operating shaft protrudes from the mounting cylinder 62b. On the outer peripheral surface of the electromagnetic solenoid 61, mounting flanges 62f extend on the front side and the rear side in the vehicle longitudinal direction (see FIG. 4).

The electromagnetic solenoid 61 is fixed on the top cover 20 by inserting the mounting cylinder 62 b into the circular hole 21 h with the protruding protrusion 22 abutting against the mounting flange 62 f and screwing the bolt 63 into the internal thread of the protruding protrusion 22 . The axial direction of the plunger 61p of the electromagnetic solenoid 61 is parallel to the axial direction of the valve operating camshaft 41 and the slide rod 53 in the central axis hole 41h thereof.

Rigidity of the top cover 20 is enhanced by forming the concave portion 20uh and the protruding portion 20up. Also, since the electromagnetic solenoid 61 is fixed in such a manner as to be located in the recessed portion 20uh, the upward protrusion amount of the electromagnetic solenoid 61 is reduced.

A pair of guide walls 23 are formed at the front and rear of the central chamber 21c within the central protrusion 21, extending downward. An elastic stopper 29 is attached to the peripheral wall 20s of the top cover 20 so as to prevent the swing arm 65 from abutting against 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, which has long side plates 65b facing each other and having the same shape, connected via long link plate portions 65a. The swing arm 65 is oriented almost parallel to the cylinder axial direction, and is positioned within the cam chain chamber 20 c of the top cover 20 . The side plate 65b has a journal bearing hole 65bh at a position above the center, and is tapered upward and downward from the journal bearing hole 65bh.

The swing arm 65 aligns the pivoting bolt 64 by inserting its upper half into the central chamber 21c of the central protrusion 21 and aligning the journal bearing holes 65hh with the pivot holes made on the front and rear lateral sides of the central chamber 21c. These holes are screwed into to be pivotably journaled in the top cover 20 .

The slide rod 53 sliding in the valve operating camshaft 41 is flush with the alignment surface S (lower surface of the elastic sealing member 18) between the top cover 20 and the cylinder head 15, and the lower end of the swing arm 65 is on the alignment surface S. Protrudes slightly below. On the other hand, the lower ends 23 a of the pair of front and rear guide walls 23 extending downward from the central protrusion 21 are positioned above the slide bar 53 . The stopper 24 on which the swing arm 65 abuts is positioned above the lower end of the guide wall 32 (see FIG. 5 ).

Since the swing arm 65 is journalled at a position above its center by the pivot bolt 64, the part below the pivot bolt 64 is longer, and as shown in FIG. Positioned above the driven cam sprocket 36 fixed to the valve operating camshaft 41 . The plunger 61 p of the electromagnetic solenoid 61 abuts on the link plate portion 65 a at the upper end, and the slide rod 53 biased by the coil spring 56 abuts on the link plate portion 65 a at the lower end below the pivot bolt 64 .

With the mounting cylinder 62b of the electromagnetic solenoid 61 fitted into the circular hole 21h of the central protrusion 21, the plunger 61p retracted by the demagnetized electromagnetic solenoid 61 abuts on the upper end of the swing arm 65 and pushes the The upper end, the lower end of the swing arm 65 that has swung abuts on the left end of the slide rod 53 biased by the coil spring 56, as shown by the two-dot chain line in FIG. 4 . In other words, the lower end of the swing arm 65 is biased by the coil spring 65 via the slide rod 53 so as not to swing freely. Therefore, even when the plunger 61p is retracted by the actuation of the electromagnetic solenoid 61, the upper end of the plunger 61p and the swing arm 65 are kept in contact with each other, and the lower end of the swing arm 65 and the slide rod 53 are also kept in contact with each other, and the power is is transmitted to the slide rod 53 so that there is no collision sound between the swing arm 65 and the slide rod 53 .

When the electromagnetic solenoid 61 is actuated, the swing arm 65 abuts against the stopper 24 and restricts its swing, thereby restricting the sliding movement to the right side of the variable cam member 50 through the slide rod 53 at a given position. , and the variable cam member 50 stops at a position slightly away from or adjacent to the steady state cam member 42 .

Since the electromagnetic solenoid 61 supported by the top cover 20 is positioned below the fuel tank 6 , its operation sound is suppressed by the fuel tank 6 and thus is hardly transmitted to passengers. In addition, since the electromagnetic solenoid 61 is protected by the fuel tank 6, a special shielding member for the electromagnetic solenoid 61 is not required, thereby reducing the number of parts.

Referring to FIG. 4, for the swing arm 65, it is assumed that its swing center passing through the pivot bolt 64 is the fulcrum P, and its upper end abutting against the plunger 61p of the electromagnetic solenoid 61 serves as a force point Q, which abuts against the slide rod. The lower end on 53 is used as the point of application R. The swing arm 65 receives the plunger 61p protruding in the left direction by the magnetization of the electromagnetic solenoid 61 at the force point Q and swings, and slides the slide rod 53 to the right at the point of action R at the lower end. On the other hand, as the electromagnetic solenoid 61 is demagnetized, the biasing force of the coil spring 56 slides the slide rod 53 to the left and pushes the plunger 61 p of the electromagnetic solenoid 61 to the right.

In other words, when the solenoid coil 61 is demagnetized, the slide rod 53 slides to the left due to the biasing force of the coil spring 56, and the variable cam member 50 slides to the left, away from the steady-state cam member 42, and the exhaust valve 34 opens to the left. Used for normal timing opening and closing of exhaust valves. By way of comparison, as the electromagnetic solenoid 61 is magnetized, the plunger 61p extends to the left, and therefore, the slide rod 53 slides to the right against the biasing force of the coil spring 56, and the variable cam member 50 slides to the right via the coupling pin 54. , and the steady state in which the exhaust valve 34 is opened and closed at normal timing by the exhaust cam lobe 42e is converted to a state in which the exhaust valve 34 is opened and closed by the variable cam lobe 50e.

Opening/closing of the exhaust valve 34 at a timing different from the normal exhaust timing is performed at a prescribed timing overlapping with the opening timing of the intake valve 33, and this opening of the exhaust valve 34 makes it possible to remain in the exhaust port The exhaust gas returns to the combustion chamber 15z.

The swing arm 65 is arranged such that its longitudinal side is almost parallel to the cylinder axial direction (almost vertical direction) and is configured such that the fulcrum P is positioned above the driven cam sprocket 36 fixed on the valve operating camshaft 41, This means that the swing arm 65 can be placed in the valve train 40 in a compact manner with a large leverage ratio.

In addition, in the swing arm 65, the force point Q, the fulcrum P and the action point R are arranged linearly in order from the top to the bottom, so that the swing arm 65 can be easily assembled in the limited space of the cam chain chamber 20c, and the swing arm 65 While reducing the weight, the swing arm 65 is prevented from receiving torsional force. In addition, since the swing arm 65 has a U-shaped section, the swing arm 65 is light in weight and provides rigidity to prevent sagging. Therefore, it is possible to move accurately at any time and transmit the action of the electromagnetic solenoid 61 to the slide mechanism 52 so that the variable cam member 50 moves so that the valve timing can be changed smoothly and accurately to efficiently perform EGR control.

Many reinforcing ribs are provided on the rear side of the top cover 20 , especially below the central protrusion 21 . This ensures the rigidity of the central protrusion 21 and the protruding boss 22 supporting the electromagnetic solenoid 61 in a cantilever manner, and the motion of the plunger 61 p of the electromagnetic solenoid 61 fixed on the protruding boss 22 is accurately transmitted to the slide mechanism 52 . In addition, since the swing arm 65 has a large leverage ratio, the required amount of motion of the electromagnetic solenoid 61 is small, so that a smaller actuator can be used. In addition, since the top cover 20 supports the swing shaft and is integrally formed with the pair of guide walls 23, its structure is simplified with fewer parts.

FIG. 10 is a top view of the cylinder head 15 . On the rear side of the top wall 20 u of the roof cover 20 , an oil passage 26 extends in such a manner that its front portion in the vehicle longitudinal direction is positioned on the left side. The oil passage 26 has four injection holes 27 directed downward. Also, three positioning pin holes 15n are formed in the upper surface of the cylinder head 15, and a positioning member 72 is fitted into each positioning pin hole 15n.

When the top cover 20 is placed on the cylinder head 15, the positioning member 72 is fitted into the positioning pin hole 15n of the top cover 20 for positioning, and the flanged bolt 70 is inserted into the mounting bolt hole 15b via the elastic member 71 and fastened. . Therefore, the movement of the top cover 20 in a direction perpendicular to the cylinder axis is restricted by the positioning member 72, and the top cover 20 is elastically supported by the cylinder head 15, thereby absorbing vibrations that would affect the operation of the variable valve timing drive mechanism 60, And make it possible to change the valve timing accurately.

The dowel hole 15 n adjacent to the oil passage 26 on the rear side of the cylinder head 15 communicates with an oil supply passage 15 a extending from the cylinder block 14 and also communicating with the oil passage 26 . Therefore, the oil supplied from the oil supply path 15 a is supplied to the oil passage 26 via the cylindrical positioning member 72 .

As shown by the two-dot chain line in FIG. 10 , the oil passage 26 is formed above the intake rocker arm 44i and the exhaust rocker arm 44e and extends obliquely in the longitudinal direction. Four injection holes 27 are positioned in the oil passage 26 so that oil is injected over the intake rocker arm 44i and the exhaust rocker arm 44e to lubricate the valve train 40 .

Since the oil sprayed on the valve train 40 via the injection hole 27 of the oil passage 26 also lubricates the spline mounted portion of the valve operating camshaft 41 that slides through the variable cam member 50, the variable cam member 50 is closer to the steady state cam. When the components 42 are removed, oil also invades the gap between them. However, in this embodiment, the swing arm 65 contacts the stopper 24 and thus prevents vibration, thereby forming a gap between the variable cam member 50 and the steady state cam member 42 such that the variable cam member 50 and the steady state The cam members 42 are not difficult to separate from each other due to the viscosity of the oil.

The oil sprayed on the valve train 40 and the oil brought up by the cam chain 37 are splashed due to the swing motion of the rocker arms 44i and 44e, the rotation of the valve operation camshaft 41, the rotation of the cam chain 37, and the like. Therefore, the swing shaft of the swing arm 65 is always lubricated by oil, and wear at the position where the swing arm 65 and the slide bar 53 abut each other is prevented.

11 is a block diagram showing the configuration of an exhaust gas recirculation controller of an internal combustion engine according to an embodiment of the present invention. The ECU 100, which is a control section serving as an exhaust gas recirculation controller for an internal combustion engine, receives signals from a Ne (number of revolutions as engine speed) sensor 102, a Tw (temperature) sensor 103, a TH (throttle opening) sensor 104, and a Pb sensor. (suction pressure) sensor 105 data. According to the crank pulse data of the crankshaft 11 detected by the Ne sensor 102 and the output value of the Pb sensor 105, the position of the internal combustion engine 10 when the crankshaft 11 rotates twice (720 degrees) is calculated by stroke identification (front/rear judgment). Based on the data from the sensors, the ECU 100 determines the ignition timing of the spark plug 19, the amount of fuel injected into the fuel chamber, and the like. The Tw sensor 103 may be designed to detect the temperature of lubricating oil if the internal combustion engine 100 is an air-cooled engine, and detect the temperature of cooling water if the internal combustion engine 10 is a water-cooled engine.

In this embodiment, the ECU 100 stores an EGR operation range map 101 (see FIG. 13 ) specifying operating conditions for performing EGR control. ECU 100 is designed to check data from Ne sensor 102 and TH sensor 104 against EGR operating range map 101 and judge whether the current operating condition of internal combustion engine 10 is suitable for EGR control.

Next, if the ECU 100 judges that the operating condition is suitable for EGR control, the ECU 100 magnetizes the electromagnetic solenoid 61 so that the variable cam member 50 engages the exhaust rocker arm 44e (see FIG. 4 ), thereby performing EGR control. On the other hand, if the ECU 100 Judging that the operating conditions are not suitable for EGR control, the ECU 100 demagnetizes the electromagnetic solenoid 61 to disengage the variable cam member 50 from the exhaust rocker arm 44e to turn off the EGR control (transition to normal operation).

Figure 12 is a graph showing the timing of actuation of the intake and exhaust valves. The timing B (solid line) to actuate the intake valve 33 and the timing A (chain line) to actuate the exhaust valve 34 pass through the intake cam lobe 42i and the exhaust cam lobe 42i formed on the steady state cam member 42, respectively. Lobe 42e (see FIG. 4) is defined.

In general, for the valve timing of the intake and exhaust valves in a four-stroke engine, the intake and exhaust valves do not open simultaneously, except for periods of overlap that span a specified range at crank zero angle (exhaust top dead center) . However, in the internal combustion engine 10 according to the present embodiment, in order to perform EGR control to return some exhaust gas from the exhaust port to the combustion chamber and recombust it, the electromagnetic solenoid 61 is magnetized so that the variable cam member 50 engages the bank. The air rocker arm 44e, so that the exhaust valve 34 can be opened during the period when the intake valve 33 is open.

More particularly, as shown by the dotted line (C) in the drawing, during the valve opening period T (for example, a crank angle range of 180°±90°) from the suction stroke to the compression stroke, by using a relatively small valve lift The exhaust valve 34 is opened to perform EGR control. The valve timing and the valve lift amount in EGR control are determined by the variable cam lobe 50e formed on the variable cam member 50 .

FIG. 13 is an EGR operating range map 101 . It is known that although the EGR control is effective during exhaust purification and the like, when the internal combustion engine 10 is within the prescribed operating condition range, it is better to turn off the EGR control when the operating condition is far from the prescribed operating condition range. In the EGR operating range map which is a 2D map, the EGR operating range is determined by the engine speed Ne and the throttle opening TH. The EGR operating range may be set, for example, as a range in which the throttle opening TH is small (eg, 0-35% opening) and the engine speed is moderate (eg, 2750-4750 rpm).

In this embodiment, the range indicated by the rectangle with a triangular cutout at the upper left corner is set as the EGR operation range D (solid line), in which the engine speed Ne is in the range of Ne1-Ne2, and the throttle opening TH is at 0 ( zero)-TH2 range. This triangular cutout in the rectangle is used to linearly increase the throttle opening Th for EGR control in the range TH1-TH2, in the range Ne1-Nea. EGR control in the triangle range, engine output is improved, and exhaust purification ability is improved.

In addition, the hysteresis setting range E (two-dot chain line) for canceling the EGR control is set within the EGR operation range D. For example, if the engine speed Ne is decreased from Ne3 while the throttle opening TH is maintained at THa, EGR control starts when the engine speed Ne2 at which the EGR control range D is determined is reached. On the other hand, if the throttle opening TH remains THa, and the engine speed Ne increases toward Ne2, the EGR control ends when Ne3, which is greater than Ne2 and determines the hysteresis setting range E, is reached. This prevents the electromagnetic solenoid 61 from being repeatedly magnetized and demagnetized near the boundary of the EGR operating range D.

As described above, the ECU 100 is configured such that EGR control starts when the operating condition of the internal combustion engine 10 is within the EGR operating range D and ends when the operating condition of the internal combustion engine 10 is outside the EGR operating range D. However, if the electromagnetic solenoid 61 is actuated as soon as it is detected that it enters or exits the EGR operating range D, the variable valve timing mechanism 60 may create a switching sound.

More specifically, to end EGR control, the variable cam member 50 slides such that the variable cam lobe 50e disengages the exhaust rocker arm 44e, and at this time, if the exhaust valve 34 is held by the variable cam lobe 50e Open, when the variable cam lobe 50e is pulled in the axial direction, the exhaust valve 34 will quickly close due to the biasing force of a valve spring (not shown) that biases the exhaust valve 34 in the closing direction. Therefore, when the umbrella-shaped portion (valve face) of the exhaust valve 34 and the valve contact portion (valve seat) of the exhaust port 15e come into rapid contact with each other, a collision sound is generated.

For this reason, this embodiment is designed so that the operation condition of the exhaust valve 34 is detected based on the crank pulse and the Pb sensor output, and when the EGR control is ended, if the exhaust valve 34 is kept open by the variable cam member 50, in waiting After the exhaust valve 34 is fully closed, the electromagnetic solenoid 61 is demagnetized, causing the variable cam lobe 50e to slide. Therefore, when the EGR control is terminated, no knocking sound is generated when the exhaust valve 34 contacts the valve seat. This embodiment is also designed such that, at the start of EGR control, in the valve opening period T in which the exhaust valve 34 is opened by the variable cam member 50, the electromagnetic solenoid 61 waits until the exhaust valve 34 is fully closed to be magnetized.

The internal combustion engine 10 according to this embodiment is designed such that the ECU 100 that executes fuel injection control executes fuel cut control to stop fuel injection during deceleration and the like at a prescribed vehicle speed and above. This fuel cut control is designed to stop fuel injection within a prescribed engine speed range, for example, when the throttle opening TH is set to a fully closed state at a prescribed vehicle speed and above.

Assuming the engine is decelerating from high speed due to throttle closing, engine braking, both vehicle speed and engine speed decrease as the elapsed time after throttle closing increases. However, when the speed is reduced to the specified low speed range, fuel injection must be restarted to avoid engine stalling, even if the throttle opening is fully closed. However, if normal injection restarts at a given engine speed, engine power will vary and affect drivability. Therefore, this embodiment is designed so that when the injection control is resumed after the fuel cut control during deceleration, the change in engine power at the reinjection is reduced by performing the fuel cut speed gradual reduction control in which the fuel cut speed is gradually reduced. Small.

This embodiment is characterized in that the engine speed at which fuel injection starts after the fuel cut control is set to a lower level than the lowest engine speed of the EGR operating range D. Specifically, referring to FIG. 13 , the engine speed NeL (for example, 2000 rpm) at the end of the fuel cut control during deceleration by closing the throttle is set to a lower level than the lowest engine speed Ne1 (for example, 2750 rpm) of the EGR operation range D . In addition, the engine speed NeH (for example, 2200 rpm) at which the fuel cut speed gradual reduction control is started is also set to a lower level than the lowest engine speed Ne1 of the EGR operation range D.

The arrangement prevents switching between the EGR operating range and the EGR non-operating range while fuel injection is being performed during deceleration. For example, if the EGR non-operating range is switched to the EGR operating range while fuel injection is being performed during deceleration, combustion conditions will become better due to EGR control, resulting in an improvement in engine output. This improves engine output during deceleration by closing the throttle, which affects drivability. On the other hand, according to the above arrangement, switching of the EGR operation range D is performed during the fuel cut control when fuel injection is not performed, which means that the EGR control can be turned on and off without affecting the engine output.

Fig. 14 is a flowchart showing EGR cam operation solenoid control. This flowchart shows the sequence of control of the EGR cam 50 (variable cam member) by the ECU 100 . In step S1 , the throttle opening TH is detected by the TH sensor 104 , and in step S2 the engine speed Ne is detected by the Ne sensor 102 .

In step S3 , the EGR operating range map 101 is looked up in the ECU 100 . In step S4, it is judged whether the throttle opening TH is within the prescribed range, and if the judgment is affirmative, the process proceeds to step S5 to judge whether the engine speed Ne is within the prescribed range. If the judgment at step S5 is affirmative, the process proceeds to step S6 to judge whether or not the engine temperature Tw is at or above a prescribed value. Therefore, in this embodiment, the engine temperature Tw as well as the throttle opening TH and the engine speed Ne are considered as EGR control start conditions.

If the judgment of step S6 is affirmative, it is considered that the EGR operation condition is satisfied, and the process proceeds to step S7, where the EGR cam operation condition flag F1=1 is set. On the other hand, if the judgment of step S4, S5 or S6 is negative, it is considered that the EGR operation condition is not satisfied, and the process proceeds to step S8, setting the EGR cam operation condition flag F=0.

Next at step S9, it is judged based on the crank pulse and the Pb sensor output whether it is within the exhaust valve operating range of the variable cam member operation. This judgment determines whether the current phase of the crankshaft 11 is within a range in which the variable cam lobe 50e of the variable cam member 50 opens the exhaust valve 34 (ie, the valve opening period T).

If the judgment of step S9 is affirmative, that is, if the EGR control is in progress and it is judged that the exhaust valve 34 is kept open by the variable cam member 50, the process proceeds to step S10 in order to judge whether it is during the opening of the exhaust valve by the variable cam member 50. Outside the operating range (valve opening period T). If the judgment of step S10 is negative, the procedure proceeds to step S11 to wait and returns to step S9.

If the judgment of step S10 is affirmative, that is, if the EGR control is in progress and it is judged that the exhaust valve 34 has been fully closed as the operation of the exhaust valve 34 by the variable cam member 50 has ended (if the EGR control is not in progress, the exhaust The gas valve should be fully closed), the process continues to step S12.

In step S12, it is judged whether the EGR cam operation condition flag F set in step S7 is 1 or not. If the judgment of step S12 is affirmative, the process proceeds to step S13 to turn on the electromagnetic solenoid 61 to start the EGR control, and the control process is ended. On the other hand, if the judgment at step S12 is negative, the process proceeds to step S14 to turn off the electromagnetic solenoid 61, end the EGR control, and end the control process.

FIG. 15 is a flowchart showing the procedure of fuel cut control during deceleration. The reference numerals in this flowchart correspond to the reference numerals in the EGR operating range map shown in FIG. 13 . In step S20, it is determined whether or not a fuel cut condition is satisfied based on a fuel cut map (not shown) stored in the ECU 100 . For example, the fuel cut condition parameters may be vehicle speed V, engine speed Ne, and throttle opening TH.

In step S21, it is judged whether a fuel cut is in progress, and then in step S22, it is judged whether the throttle is fully closed. If the determination of steps S20, S21 and S22 is affirmative, the process proceeds to step S23 to determine whether the engine speed Ne is greater than a prescribed value NeH (for example, 2200 rpm) or more. If the judgment in step S23 is affirmative, the process proceeds to S24 to judge whether the engine temperature Tw is a prescribed value TwL (for example, 40 degrees) or above.

If the judgment of step S23 is negative, that is, if it is judged that the engine speed Ne is within the prescribed low speed range, the process proceeds to step S25. Also if the judgment of step S24 is negative, that is, if it is judged that the engine temperature Tw is within the prescribed low temperature range, then the process proceeds to step S25. On the other hand, if the judgment of step S24 is affirmative, that is, if it is judged that the engine temperature Tw is in the prescribed high temperature range, the control process ends.

In step S25, it is judged whether or not the engine speed Ne exceeds a lower prescribed value NeL (for example, 2000 rpm). If the judgment at step S25 is affirmative, the process proceeds to step S26 to start the fuel cut speed gradual reduction control, and at step S27 to cause the fuel cut speed gradual reduction control count to increase. A fuel cut rate taper control counter may be incorporated into the ECU 100 .

In step S28, it is judged whether the fuel cut speed gradually decreasing control counter has reached a prescribed value, and if the judgment is affirmative, the process proceeds to step S29 to end the fuel cut control (re-execute fuel injection control), and if the judgment is negative , the control process ends. If the judgment at step S25 is negative, the process proceeds to step S29 to force the end of the fuel cut control and end the control process. Through the fuel cut control, the fuel cut speed is gradually decreased from the fuel cut control state, thereby suppressing a change in engine output at the time of re-injection of fuel (when re-injecting fuel), so that drivability is improved.

The structure of the variable valve timing mechanism, the EGR operation range map setting, the engine speed setting value at which the fuel cut control is terminated, etc. are not limited to the above embodiments, and can be adjusted in various ways. The exhaust gas recirculation controller of an internal combustion engine according to the present invention can be applied not only to motorcycles, but also to other various vehicles, such as sidecar type three-wheel/four-wheel vehicles and general-purpose engines.

The invention having thus been described, it will be understood that the invention may be varied in many ways. Such modifications are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be understood by one of ordinary skill in the art are intended to be included within the scope of the claims.

Claims (20)

1. An exhaust gas recirculation controller of an internal combustion engine for performing EGR control so as to open an exhaust valve (34) of an internal combustion engine (10) by operating an actuator (61) in a stroke other than the exhaust stroke ), returning some exhaust gas to the combustion chamber (15z) and allowing it to burn again; a control section (100) for controlling the actuator (61) according to an EGR operating range map (101) using at least an engine speed (Ne) and a throttle opening (TH) as parameters; The control part (100) cuts off the fuel injection of the fuel injection system during deceleration of the vehicle (1) when the fuel cutoff condition is satisfied; The fuel cut condition is determined by a fuel cut map determined by vehicle speed (V), engine speed (Ne) and throttle opening (TH), and is set to (NeL) or less, end fuel injection cutoff, and re-inject fuel; and The lowest value (Nel) of the engine speed (Ne) of the EGR operating range (D) constituting the EGR operating range map (101) is set to a value higher than the lower specified value (NeL) of the fuel cut condition; The exhaust gas recirculation controller of the internal combustion engine is characterized in that: wherein EGR is controlled by operating said actuator (61) so as to be in a state where said exhaust valve (34) is actuated according to a cam profile of a variable cam member (50) rotating synchronously with a valve operating camshaft (41) and said exhaust valve (34) is switched on or off according to switching between states where the cam profile of said cam member (50) is not actuated; The actuator (61) is capable of sliding a variable cam member (50) attached to the valve operating camshaft (41) to operate the exhaust valve axially slidable without relative rotation (34); the EGR control is turned on or off by the actuator (61) sliding the variable cam member (50) into and out of engagement with the exhaust valve (34); and When the EGR control is off, the exhaust valve (34) passes through an exhaust cam lobe (42e) fixed to the valve operating camshaft (41) and engaged with an exhaust rocker arm (44e) operation, with the EGR control on, the exhaust valve (34) passes through the variable cam member (50) and the exhaust cam lobe (42e) engaged with the exhaust rocker arm (44e) ) both operate. 2. The exhaust gas recirculation controller for an internal combustion engine according to claim 1, wherein a higher prescribed value (NeH) as a timing of starting the fuel cut speed gradual reduction control to gradually decrease the fuel cut speed is set at a constituting The EGR operating range (D) is between the lowest value (Nel) of the engine speed (Ne) and the lower specified value (NeL) of the fuel cut condition. 3. The exhaust gas recirculation controller for an internal combustion engine according to claim 1, wherein the upper prescribed value (NeH) as a timing to gradually reduce the fuel cut speed by starting the fuel cut speed gradual reduction control is set at Between the lowest value (Nel) of the engine speed (Ne) constituting the EGR operating range (D) and the lower specified value (NeL) of the fuel cut condition. 4. The exhaust gas recirculation controller of an internal combustion engine according to claim 2, wherein the difference between said upper specified value (NeH) and said minimum value (Nel) is greater than said lower specified value (NeL ) and the said higher specified value (NeH). 5. The exhaust gas recirculation controller of an internal combustion engine according to claim 2, wherein said control section (100) starts a counter when said fuel cut speed gradual reduction control is started, and when said counter reaches a prescribed value , the control section (100) ends the fuel cut speed gradual reduction control and fuel cut to resume fuel injection. 6. The exhaust gas recirculation controller of an internal combustion engine according to claim 1, wherein said EGR operating range map (101) is a 2D map comprising said engine speed (Ne) and throttle opening (TH) limit; and The EGR operating range (D) is obtained by dividing an almost triangular prescribed range with low engine speed (Ne) and high throttle opening (TH) from where the engine speed (Ne) lies within the prescribed range (Nel-Ne2) In addition, the throttling device opening (TH) is excluded from a rectangle within a predetermined range (0-TH2). 7. The exhaust gas recirculation controller of an internal combustion engine according to claim 1, wherein said EGR operating range map (101) is a 2D map comprising said engine speed (Ne) and throttle opening (TH) limit; and The EGR operating range (D) is obtained by dividing an almost triangular prescribed range with low engine speed (Ne) and high throttle opening (TH) from where the engine speed (Ne) lies within the prescribed range (Nel-Ne2) In addition, the throttling device opening (TH) is excluded from a rectangle within a predetermined range (0-TH2). 8. The exhaust gas recirculation controller of an internal combustion engine according to claim 2, wherein said EGR operating range map (101) is through a 2D map comprising said engine speed (Ne) and throttle opening (TH) limit; and The EGR operating range (D) is obtained by dividing an almost triangular prescribed range with low engine speed (Ne) and high throttle opening (TH) from where the engine speed (Ne) lies within the prescribed range (Nel-Ne2) In addition, the throttling device opening (TH) is excluded from a rectangle within a predetermined range (0-TH2). 9. The exhaust gas recirculation controller of an internal combustion engine according to claim 1, wherein said fuel cut condition includes said throttle opening (TH) being fully closed. 10. The exhaust gas recirculation controller of an internal combustion engine according to claim 2, wherein said fuel cut condition includes said throttle opening (TH) being fully closed. 11. The exhaust gas recirculation controller of an internal combustion engine according to claim 1, wherein said EGR operating range map (101) includes a hysteresis setting range (E) for setting a hysteresis characteristic for said EGR operating range (D). 12. The exhaust gas recirculation controller of an internal combustion engine according to claim 2, wherein said EGR operating range map (101) includes a hysteresis setting range (E) for setting a hysteresis characteristic for said EGR operating range (D). 13. An exhaust gas recirculation controller of an internal combustion engine for performing EGR control so as to open an exhaust valve of said internal combustion engine (10) by operating an actuator (61) in a stroke other than the exhaust stroke (34), returning some of the exhaust gas to the combustion chamber (15z) and allowing it to burn again, providing a control section (100) for controlling said actuator (61) according to an EGR operating range map (101) using at least an engine speed (Ne) and a throttle opening (TH) as parameters; The exhaust gas recirculation controller of the internal combustion engine is characterized in that: wherein EGR is controlled by operating said actuator (61) so as to be in a state where said exhaust valve (34) is actuated according to a cam profile of a variable cam member (50) rotating synchronously with a valve operating camshaft (41) and said exhaust valve (34) is switched on or off according to switching between states where the cam profile of said cam member (50) is not actuated; When the operating condition of the internal combustion engine (10) is within the EGR operating range (D) of the EGR operating range map (101), the control section (100) according to the cam profile of the variable cam member (50) The exhaust valve (34) is actuated to perform EGR control, and the variable cam member (50) opens the exhaust valve (34) for a period (T) under operating conditions of the internal combustion engine (10) When outside the EGR operating range (D) during the process, the control section (100) waits until the valve opening period (T) ends and the exhaust valve (34) is fully closed, followed by switching To a state where actuation of the exhaust valve (34) is not performed according to the cam profile of the variable cam member (50), the EGR control is turned off. 14. The exhaust gas recirculation controller of an internal combustion engine according to claim 13, wherein said actuator (61 ) is capable of causing a variable cam member (50) attached to said valve operating camshaft (41 ) to sliding to operate said exhaust valve (34) in an axially slidable manner without relative rotation; the EGR control is turned on or off by the actuator (61) sliding the variable cam member (50) into and out of engagement with the exhaust valve (34); and When the EGR control is off, the exhaust valve (34) passes through an exhaust cam lobe (42e) fixed to the valve operating camshaft (41) and engaged with an exhaust rocker arm (44e) operation, with the EGR control on, the exhaust valve (34) passes through the variable cam member (50) and the exhaust cam lobe (42e) engaged with the exhaust rocker arm (44e) ) both operate; and When the operating condition of the internal combustion engine (10) is within the EGR operating range (D) of the EGR operating range map (101), the control portion (100) causes the variable cam member (50) to align with the The exhaust rocker arm (44e) is engaged to perform EGR control, and the variable cam member (50) opens the exhaust valve (34) for a period (T) under the operating condition of the internal combustion engine (10) When outside the EGR operating range (D) during the process of The variable cam member (50) is disengaged to shut off the EGR control. 15. The exhaust gas recirculation controller of an internal combustion engine according to claim 13, wherein the operating condition of the internal combustion engine (10) is outside the EGR operating range (D) and simultaneously not in the variable cam member (50) The control portion (100) disengages the variable cam member (50) without waiting for a period (T) of opening the exhaust valve (34). 16. The exhaust gas recirculation controller of an internal combustion engine according to claim 13, wherein the variable cam member (50) opens the exhaust valve (34) at an operating condition of the internal combustion engine (10) When entering the EGR operating range (D) of the EGR operating range map (101) during a period (T), the control section (100) waits until the valve opening period (T) ends and the exhaust valve (34) is fully closed and then engages the variable cam member (50). 17. The exhaust gas recirculation controller of an internal combustion engine according to claim 13, wherein whether the operating condition of the internal combustion engine (10) is at the time when the variable cam member (50) opens the exhaust valve (34) The period (T) is detected by at least crank pulse data of the internal combustion engine (10). 18. The exhaust gas recirculation controller of an internal combustion engine according to claim 13, wherein said EGR operating range map (101) includes a hysteresis setting range (E) for setting a hysteresis characteristic for said EGR operating range (D). 19. The exhaust gas recirculation controller of an internal combustion engine according to claim 13, wherein said EGR operating range map (101) is through a 2D map comprising said engine speed (Ne) and throttle opening (TH) limit; and The EGR operating range (D) is obtained by dividing an almost triangular prescribed range with a low engine speed (Ne) and a high throttle opening (TH) from the engine speed (Ne) within the prescribed range (Nel-Ne2) and The throttling device opening (TH) is formed by excluding a rectangle within a predetermined range (0-TH2). 20. The exhaust gas recirculation controller for an internal combustion engine according to claim 13, wherein a plunger (61p) as an operating shaft of the actuator (61) is positioned parallel to the valve operating camshaft (41) ; said variable cam member (50) is constantly biased by a coil spring (56) toward disengagement from said exhaust valve (34); The sliding movement of the plunger (61p) is via a swing arm ( 65) to said variable cam member (50); and When the actuator (61) is magnetized, the variable cam member (50) slides against the biasing force of the coil spring (56) and the variable cam member (50) engages the exhaust rocker lever arm (44e), and on the other hand, when the actuator (61) is demagnetized, the variable cam member (50) and the exhaust rocker arm (44e) are biased by the coil spring (56) The pressure disengages again.