JP5269622B2 - Engine and motorcycle equipped with the same - Google Patents

Description

  The present invention relates to an engine and a motorcycle including the engine. More specifically, the lift amount of at least one of an intake valve and an exhaust valve is switched to a first lift amount or a second lift amount larger than the first lift amount. The present invention relates to an engine having a variable valve mechanism and a motorcycle including the same.

  For engines such as motorcycles and automobiles, when the rotational speed is low (low speed operation), the valve is opened small (lift amount is reduced), and when the rotational speed is high (high speed operation), the valve is opened largely. A variable valve mechanism (increasing the lift amount) is employed. Specifically, a low speed cam with a small amount of displacement and a high speed cam with a large amount of displacement are provided around the camshaft. A low-speed rocker arm that swings according to the low-speed cam and a high-speed rocker arm that swings according to the high-speed cam are provided adjacent to each other. A through hole is formed in each of the low-speed and high-speed rocker arms, and a pin is inserted therein and is slid by hydraulic pressure. Since the pin is housed in the through hole of the low speed rocker arm at low speed, the high speed rocker arm is separated from the low speed rocker arm. Therefore, the low-speed rocker arm swings small according to the low-speed cam, thereby driving the valve small. Although the high-speed rocker arm swings greatly in response to the high-speed cam, it is separated from the low-speed rocker arm, so that the valve is not driven at all (is swung). On the other hand, at the time of high speed, since the pin is disposed across the through holes of both the low speed and high speed rocker arms, the low speed rocker arm is connected to the high speed rocker arm. Therefore, the low-speed rocker arm swings greatly according to the high-speed cam together with the high-speed rocker arm, thereby driving the valve largely.

  However, even if the ECU (Electronic Control Unit) commands the variable valve mechanism to move the pin by controlling the hydraulic pressure, the pin is actually inserted into the through hole of the high-speed rocker arm from the command. It takes some time to complete. Therefore, there is a problem that it is too early for the ECU to change the combustion conditions such as the fuel injection amount immediately after the command. As a method for solving such a problem, there is a method in which a sensor for directly detecting the actual movement of the pin is provided, and the combustion state of the engine is changed to a high speed when the sensor detects the movement of the pin. However, it is difficult to provide such a sensor around the pin for reasons such as high temperature, intense vibration, a lot of oil stains, and almost no extra space.

  Japanese Patent Laying-Open No. 2003-083148 (Patent Document 1) describes a failure detection device in a deceleration-cylinder cylinder engine vehicle that can reliably detect a failure mainly by monitoring hydraulic pressure of hydraulic oil. An intake pipe negative pressure sensor for detecting the intake pipe negative pressure is provided in the intake passage. A secondary air passage that connects the upstream side and the downstream side of the throttle valve is provided in the intake passage, and a control valve that opens and closes the secondary air passage is provided in the secondary air passage. The secondary air passage is for supplying a small amount of air into the cylinder even when the throttle valve is fully closed. The control valve is opened and closed according to the intake pipe negative pressure detected by the intake pipe negative pressure sensor. The engine has three cylinders equipped with variable valve timing mechanisms (cylinder deactivation mechanisms) on the intake side and exhaust side and one normal valve mechanism that does not perform deceleration cylinder deactivation operations. Has a cylinder. That is, the engine is a cylinder resting engine that can be switched between a normal operation in which four cylinders including three cylinders that can be deactivated and a decelerating cylinder deactivation operation in which three cylinders are deactivated. The valve and the exhaust valve have a structure in which operation can be stopped by a variable valve timing mechanism. The failure determination of a cylinder with no cylinder is to detect a failure that makes it impossible to perform cylinder deactivation when decelerating. Specifically, this is a case where the intake pipe negative pressure during deceleration is higher than the predetermined determination pressure. In a three-cylinder idle decelerating cylinder-cylinder engine, the intake pipe negative pressure is determined according to the engine speed. Further, in an engine in which two cylinders are deactivated, the intake pipe negative pressure is on the higher negative pressure side than in the case of three cylinder deactivation, and in an engine in which one cylinder is deactivated, the intake pipe negative pressure is further on the high negative pressure side. In the case of an engine having no cylinders to be stopped, the intake pipe negative pressure is on the high negative pressure side. Therefore, when the three cylinders are not normally stopped, the intake pipe negative pressure is on the high negative pressure side as compared with the case where the three cylinders are stopped. This is used to determine the failure of the cylinder with no cylinder. However, this device cannot detect the switching of the lift amount.

JP 2003-083148 A

  An object of the present invention is to provide an engine that can indirectly detect actual switching of a lift amount and a motorcycle including the same.

Means for Solving the Problems and Effects of the Invention

The engine according to the present invention includes a variable valve mechanism, an intake pressure sensor, sampling means, and switching determination means. The variable valve mechanism switches the lift amount of at least one of the intake and exhaust valves to a first lift amount or a second lift amount that is larger than the first lift amount , and the lift amount is the second lift amount. When the exhaust valve is closed, a part of the period during which the exhaust valve is open and a part of the period during which the intake valve is open are overlapped so that the intake valve starts to open, and the lift amount is the first lift amount. In this case, the period during which the exhaust valve is opened and the period during which the intake valve is open are not overlapped so that the intake valve starts to open after the exhaust valve has been closed . The intake pressure sensor is provided in an intake path leading to the intake valve, and detects the intake pressure. The sampling means samples the intake pressure detected between the exhaust stroke and the intake stroke among the intake pressure detected by the intake pressure sensor. The switching determination means determines that the variable valve mechanism has switched the lift amount from the first lift amount to the second lift amount when the intake pressure provided from the sampling means becomes higher than a predetermined value.

According to the present invention, when the intake pressure detected by the intake pressure sensor becomes higher than a predetermined value, the variable valve mechanism determines that the lift amount has been switched from the first lift amount to the second lift amount. The actual switching of the lift amount can be detected indirectly. Since the intake pressure within a period during which the intake pressure may be higher than the predetermined value is sampled, the determination accuracy of the lift amount switching is improved.

  In one embodiment of the present invention, when the lift amount is the second lift amount, the variable valve mechanism starts to open the intake valve before the exhaust valve is closed.

  In another embodiment of the present invention, the engine further includes sampling means for sampling the intake pressure detected during the intake and exhaust strokes of the intake pressure detected by the intake pressure sensor and providing it to the switching determination means. Prepare.

  In this case, since the intake pressure within a period during which the intake pressure may be higher than the predetermined value is sampled, the determination accuracy of the lift amount switching is improved.

  In still another embodiment of the present invention, the engine further includes a switching command unit and a failure determination unit. The switching command means commands the variable valve mechanism to switch the lift amount. The failure determining means determines that the variable valve mechanism is out of order when the switching determining means does not determine that the lift amount has been switched despite the switching instruction means being instructed to switch the lift amount.

  In still another embodiment of the present invention, the engine further includes time limit means for setting a predetermined time limit. The failure determination means is permitted when the switching determination means does not determine that the lift amount has been switched even though the time limit set by the time limitation means has elapsed since the switching instruction means was instructed to switch the lift amount. The variable valve mechanism is determined to be a failure.

  In yet another embodiment of the invention, the engine further comprises a single cylinder.

  In yet another embodiment of the invention, the predetermined value is higher than atmospheric pressure. More specifically, a value that is 10 to 30 KPa higher than the atmospheric pressure is set as the predetermined value.

  The engine is provided in, for example, a motorcycle.

1 is a side view showing an overall configuration of a motorcycle including a valve operating control device according to an embodiment of the present invention. It is sectional drawing which shows the structure of the engine shown in FIG. It is sectional drawing of the III-III line in FIG. It is a top view of the cam carrier shown in FIG. 2 and various components assembled | attached to it. It is sectional drawing of the VV line in FIG. It is sectional drawing of the VI-VI line in FIG. It is a disassembled perspective view of the cam carrier shown in FIG. 2 and various components assembled | attached to it. It is a perspective view of the cam carrier shown in FIG. 7 and various components assembled | attached to it. It is a functional block diagram which shows the structure of ECU (valve control apparatus) shown in FIG. FIG. 10 is a flowchart showing a request cam determination operation by the ECU shown in FIG. 9. It is a flowchart which shows the determination operation | movement of the real cam by ECU shown in FIG. FIG. 12 is a timing chart showing the determination operation shown in FIG. 11. FIG. 10 is a flowchart showing a cam switching operation by the ECU shown in FIG. 9. FIG. 14 is a timing diagram illustrating a case where the switching operation illustrated in FIG. 13 is normal. FIG. 14 is a timing diagram illustrating a case where the switching operation illustrated in FIG. 13 is abnormal.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

(1) Overall Configuration of Motorcycle With reference to FIG. 1, a motorcycle 100 according to an embodiment of the present invention includes a main frame 1. A head pipe 2 is provided at the front end of the main frame 1. A front fork 3 is rotatably provided on the head pipe 2. A front wheel 4 is rotatably supported at the lower end of the front fork 3. A handle 5 is attached to the upper end of the front fork 3.

  A cowl 6 is provided so as to cover the front and side of the main frame 1. A DOHC (Double Over Head Camshaft) engine 7 is provided in the center of the main frame 1. An air cleaner box 8 is provided above the engine 7. An intake pipe 10 is provided so as to connect the air cleaner box 8 and the intake port 9 of the engine 7.

  An intake passage 11 that connects the air cleaner box 8 and the outside is provided at the front portion of the motorcycle 100 so as to be covered with the cowl 6. One end of the intake passage 11 is open at the front surface of the cowl 6. Air outside the motorcycle 100 is taken into the engine 7 through the intake passage 11, the air cleaner box 8 and the intake pipe 10.

  One end of an exhaust pipe 13 is connected to the exhaust port 12 of the engine 7. The other end of the exhaust pipe 13 is connected to the muffler device 14. Burned gas generated by the combustion of the mixer in the engine 7 is discharged to the outside through the exhaust pipe 13 and the muffler device 14.

  A seat 15 is provided on the upper portion of the engine 7. An ECU (Electronic Control Unit) 16 that controls the operation of each part of the motorcycle 100 is provided below the seat 15. Details of the ECU 16 will be described later. A rear arm 17 is connected to the main frame 1 so as to extend rearward of the engine 7. The rear arm 17 rotatably holds the rear wheel 18 and the rear wheel driven sprocket 19. A chain 20 is attached to the rear wheel driven sprocket 19. The power generated by the engine 7 is transmitted to the rear wheel driven sprocket 19 via the chain 20. Thereby, the rear wheel 18 rotates.

(2) Configuration of Engine and Variable Valve Mechanism The engine 7 includes a variable valve mechanism that switches the lift amounts of the intake and exhaust valves to two stages, low speed and high speed. Specifically, referring to FIGS. 2 and 3, the engine 7 includes a cylinder 701, a cylinder head 702 that is detachably attached to the cylinder 701, and a cam carrier 703 that is detachably attached to the cylinder head 702. Is provided. For example, in the case of a single cylinder engine, one cylinder 701 is provided.

  Referring to FIG. 2, the cylinder head 702 includes an intake port 9, an exhaust port 12, an intake valve 22, an exhaust valve 24, valve springs 26 and 28, and valve spring accommodating spaces 30 and 32. This engine is a four-valve system, and two intake valves 22 and two exhaust valves 24 are provided. The valve springs 26 and 28 are wound around the rods 34 and 36 of the intake and exhaust valves 22 and 24, respectively, and are accommodated in the valve spring accommodating spaces 30 and 32, respectively. A partition wall 37 is formed between the intake side valve spring accommodating space 30 and the exhaust side valve spring accommodating space 32. Referring to FIG. 3, a partition wall 38 is also formed between the two intake side valve spring accommodating spaces 30. Although not shown because it is the same as FIG. 3, a partition wall is also formed between the two exhaust side valve spring accommodating spaces 32. The partition wall 38 in this example has the same thickness everywhere, but the thickness may differ depending on the location.

  Referring to FIGS. 2 and 4 to 8, cam carrier 703 includes cam bearing portions 44 and 46 that rotatably support two camshafts 40 and 42, and a rocker that supports rocker shafts 48 to 51. A shaft support portion 52 and hydraulic cylinder support portions 43 and 45 are provided. The cam bearing portions 44 and 46, the rocker shaft support portion 52, and the hydraulic cylinder support portions 43 and 45 are integrally configured. 4 and 6, the cam bearing portions 44 and 46 are arranged side by side on a straight line 55 in a plane perpendicular to the camshafts 40 and 42 through the bore center 53 (center of the cylinder 701).

  7 and 8, the cam bearing portions 44 and 46 have semicircular cutouts 54 and 56, respectively, on which the camshafts 40 and 42 lie. The camshafts 40 and 42 have a low speed cam 39 with a small displacement amount and a high speed cam 41 with a large displacement amount. Holders 62 and 64 having notches 58 and 60 symmetrical to the notches 54 and 56 are attached to the cam bearing portions 44 and 46 with bolts 66 and 67 so as to sandwich the camshafts 40 and 42. Thereby, the camshafts 40 and 42 are rotatably supported.

  4 to 8, the rocker shaft support portion 52 includes a rectangular parallelepiped center portion 68, plate-like end portions 70 and 72, and a connecting portion that connects the center portion 68 and the end portions 70 and 72. 74. A circular through hole 78 is formed in the central portion 68 so that the spark plug 76 can be attached to and detached from the cylinder head 702. Rocker shafts 48 to 51 are attached to the rocker shaft support portion 52 in parallel with the camshafts 40 and 42. Four rocker shafts 48 to 51 are provided corresponding to the four valves 22 and 24. Specifically, the rocker shafts 48 and 50 are bridged between the central portion 68 and the end portion 70. The rocker shafts 49 and 51 are bridged between the central portion 68 and the end portion 72. The rocker shafts 48 and 50 are abutted with the rocker shafts 49 and 51 in the central portion 68, respectively. Within the central portion 68, the rocker shafts 48 to 51 are cut out in an arc shape along the through hole 78.

  2 to 8, low-speed rocker arms 80 to 83 are swingably supported on the rocker shafts 48 to 51. Four low-speed rocker arms 80 to 83 are provided corresponding to the four valves 22 and 24. The tip portions of the low-speed rocker arms 80 to 83 push the shaft end surfaces (surfaces of the shaft ends) 79 of the intake and exhaust valves 22 and 24. The low-speed rocker arms 80 and 81 swing according to the low-speed cam 39 of the intake side camshaft 40, thereby pushing down the intake valve 22 directly. The low-speed rocker arms 82 and 83 swing according to the low-speed cam 39 of the exhaust side camshaft 42, thereby pushing down the exhaust valve 24 directly.

  High-speed rocker arms 84 to 87 are also swingably supported on the rocker shafts 48 to 51. Four high-speed rocker arms 84 to 87 are also provided corresponding to the four valves 22 and 24. The high speed rocker arms 84 to 87 are adjacent to the low speed rocker arms 80 to 83, respectively. The high-speed rocker arms 84 and 85 swing according to the high-speed cam 41 of the intake side camshaft 40. The high speed rocker arms 84 and 85 do not push down the intake valve 22 directly. The high speed rocker arms 86 and 87 swing according to the high speed cam 41 of the exhaust side camshaft 42. The high-speed rocker arms 86 and 87 do not push down the exhaust valve 24 directly.

  With reference to FIGS. 6 and 7, the low-speed rocker arms 80 to 83 are arranged on the cam bearing portions 44 and 46 side of the high-speed rocker arms 84 to 87, and have circular through holes 88. The through hole 88 is formed in parallel with the rocker shafts 48 to 51. A cylindrical connecting pin 90 is inserted into the through-hole 88 so as to slide.

  Referring to FIG. 7, the engine 7 is also provided with an actuator 89 that reciprocates the connecting pin 90 in the through hole 88. Specifically, referring to FIGS. 3, 4, and 7, the actuator 89 includes a cylindrical hydraulic cylinder 92 and a columnar hydraulic piston 94.

  The connecting pin 90 has a circular flange 96 at its head. A spring 98 is wound around the connecting pin 90. The connecting pin 90 is inserted so as to be able to slide into the through hole 88 from the bottom portion. Therefore, the connecting pin 90 is urged toward the hydraulic cylinder support portions 43 and 45 side. Further, the length of the connecting pin 90 is longer than the length of the through hole 88. Therefore, when the connecting pin 90 is pushed into the through hole 88 to the end, the bottom of the connecting pin 90 protrudes from the opposite side of the through hole 88.

  The hydraulic cylinder 92 is provided in the hydraulic cylinder support portions 43 and 45. Specifically, a circular through hole 99 is formed below the notch 54 of the cam bearing portions 44 and 46. The hydraulic cylinder 92 is fitted in the through hole 99 and fixed in the hydraulic cylinder support portions 43 and 45.

  In this example, a through hole 99 for the hydraulic cylinder 92 is formed in the hydraulic cylinder support portions 43 and 45, and the hydraulic cylinder 92 is fitted into the through hole 99, but nothing is fitted into the through hole 99, and the through hole 99 is inserted. Can also be used as a hydraulic cylinder.

  Further, in this example, the hydraulic pistons 94 on both sides are inserted into the hydraulic cylinders 92 fitted in the common through holes 99, but two independent non-through holes having different axial centers are respectively provided in the hydraulic cylinder support portions. You may make it open from both sides and insert a hydraulic cylinder in those non-through holes. In this case, since the hydraulic cylinders are arranged in a direction perpendicular to the camshaft, the width of the hydraulic cylinder support portion can be further reduced.

  The hydraulic piston 94 has a circular rod 102 at its head. The hydraulic piston 94 is inserted so that it can slide into the hydraulic cylinder 92 from its bottom. The head portion (102) of the hydraulic piston 94 comes into contact with the head portion (鍔 96) of the connecting pin 90.

  Thus, since the hydraulic cylinder 92 and the hydraulic piston 94 are disposed below the cam bearing portions 44 and 46, the actuator 89 can be mounted in a compact manner even in a small engine having a narrow valve spring. In the case of this example, as shown in FIG. 3, the hydraulic cylinder support 43 is wider than the interval between the two intake side valve springs 26. That is, the thickness D1 of the hydraulic cylinder support portion along the axial direction of the camshaft 40 is larger than the outer diameter interval D2 of the valve spring 26.

  With reference to FIGS. 6 to 8, the high-speed rocker arms 84 to 87 have a butt portion of the connecting pin 90 protruding from the through hole 88 and a catch portion 104 to be caught. The catching part 104 is a semicircular cutout, and the connecting pin 90 is engaged with it.

  Referring to FIGS. 2, 7, and 8, a lost motion spring shaft 106 is attached to the rocker shaft support portion 52 in parallel with the camshafts 40 and 42. Four lost motion spring shafts 106 are provided corresponding to the four valves 22, 24. Specifically, the lost motion spring shaft 106 is bridged between the central portion 68 and the end portions 70 and 72. A lost motion spring 108 is wound around the lost motion spring shaft 106 and hooked to the high speed rocker arms 84 to 87 and the connecting portion 74. Specifically, each of the high-speed rocker arms 84 to 87 has a latching portion 110 cut out in a semicircular shape, and one end of the lost motion spring 108 is latched here. The connecting portion 74 has a latching portion 112 that is perforated in a rectangular shape, and the other end of the lost motion spring 108 is latched thereon. Accordingly, the high-speed rocker arms 84 to 87 are urged toward the high-speed cam 41.

  Referring to FIG. 2, on the intake side, the axis of the lost motion spring shaft 106 is connected to the axis of the intake camshaft 40, the axis of the rocker shaft 48, and the center point of the shaft end surface 79 of the intake valve 22. Arranged outside the range. Further, on the exhaust side, the axis of the lost motion spring shaft 106 is disposed outside the range connected by the axis of the exhaust side camshaft 42, the axis of the rocker shaft 50, and the center point of the shaft end surface 79 of the exhaust valve 24. Is done.

  With reference to FIGS. 2 and 4 to 6, the cam carrier 703 is attached to the cylinder head 702 with bolts 67 and 114. With reference to FIGS. 5 and 6, the lower surfaces 116 of the cam bearing portions 44 and 46 are joined to the upper surface 118 of the cylinder head 702. A groove 120 communicating with the hydraulic cylinder 92 is formed on the lower surface 116 of the cam bearing portions 44 and 46. The groove 120 constitutes an oil passage. Referring to FIG. 7, hydraulic cylinder 92 has an opening 122 communicating with groove 120. Accordingly, oil sent from a hydraulic pump (not shown) flows from the groove 120 through the opening 122 into the hydraulic cylinder 92 via an OCV (Oil Control Valve) 139 (FIG. 9). Each groove 120 feeds oil to both sides and pushes out hydraulic pistons 94 on both sides. That is, each groove 120 is shared by the hydraulic pistons 94 on both sides thereof.

  Since the groove 120 opens to the lower surface 116 side, it is easier to form the groove 120 than the hole. The groove 120 may be formed on the upper surface 118 of the cylinder head 702 instead of the lower surface 116 of the cam carrier 703. The groove 120 in this example is straight, but may be bent. Even if it is bent in a complicated manner, it can be easily formed because it is a groove.

  With reference to FIGS. 2, 5, and 7, the central portion 68 and the end portions 70 and 72 of the rocker shaft support portion 52 have a convex portion 124 that protrudes from the lower surface 116 of the cam bearing portions 44 and 46. The rocker shafts 48 to 51 are attached to the convex portion 124.

  At high speed, by opening the OCV 139 on the oil passage, the hydraulic pressure in the groove 120 is increased, and the hydraulic piston 94 is pushed outward. In response to this, the connecting pin 90 is pushed and moved into the through holes 88 of the low-speed rocker arms 80 to 83. Thereby, the bottom of the connecting pin 90 jumps out from the opposite side of the through hole 88. Since the high-speed rocker arms 84 to 87 are urged in the direction of the high-speed cam 41 by the lost motion spring 108, the catching portion 104 is engaged with the connecting pin 90 protruding from the through hole 88. Therefore, the low-speed rocker arms 80 to 83 and the high-speed rocker arms 84 to 87 are connected. When the high-speed rocker arms 84 to 87 are largely swung according to the high-speed cam 41 having a large displacement, the low-speed rocker arms 80 to 83 are also largely swung together with the high-speed rocker arms 84 to 87. In response to this, the low-speed rocker arms 80 to 83 push down the intake or exhaust valves 22 and 24 on the shaft end surface 79 and open the intake or exhaust valves 22 and 24 greatly.

  On the other hand, at low speed, the OCV 139 on the oil passage is closed to lower the hydraulic pressure in the groove 120, and the connecting pin 90 is pushed back toward the hydraulic cylinder support portions 43 and 45 by the elastic force of the spring 98. As a result, the hydraulic piston 94 is pushed into the hydraulic cylinder 92, and the bottom of the connecting pin 90 is completely accommodated in the through hole 88. Therefore, the low-speed rocker arms 80 to 83 and the high-speed rocker arms 84 to 87 are separated. When the low-speed rocker arms 80 to 83 are oscillated small according to the low-speed cam 39 having a small displacement, the low-speed rocker arms 80 to 83 push down the intake or exhaust valves 22 and 24 at the shaft end surface 79, and the intake or exhaust valves 22 and 24 Open small. At this time, the high-speed rocker arms 84 to 87 are largely swung according to the high-speed cam 41. However, since the bottom portion of the connecting pin 90 does not protrude from the through hole 88, the high-speed rocker arms 84 to 87 are not pushed down (i.e., swung).

  Referring to FIG. 2 again, an intake pressure sensor 21 for detecting the intake pressure is provided in the intake port 9. Based on the intake pressure detected by the intake pressure sensor 21, the amount of air sucked into the engine 7 is calculated, and the cam is actually switched to the low speed cam 39 or switched to the high speed cam 41. Is determined. Details will be described later. On the upstream side of the intake pressure sensor 21 of the intake port 9, a throttle valve (not shown) for adjusting the amount of intake air is provided. The intake air amount may be adjusted by an ISC (Idle Speed Control) valve.

(3) Configuration of ECU Next, referring to FIG. 9, the ECU 16 includes a microcomputer 161 and a peak hold circuit 162. The microcomputer 161 includes a storage area 163 that stores the switching determination value map, a storage area 164 that stores the FI map, a storage area 165 that stores the requested cam state, and a storage area 166 that stores the actual cam state. In the switching determination value map, predetermined switching determination values are registered in accordance with the rotational speed of the engine 7 and the throttle opening. An appropriate fuel injection amount, fuel injection timing, and ignition timing are registered in the FI map. The requested cam state indicates whether the cam should be switched to the low speed cam 39 or the high speed cam 41. The actual cam state indicates whether the cam is actually switched to the low speed cam 39 or the high speed cam 41.

  The microcomputer 161 outputs a cam signal CA output from the cam sensor 23, a crank signal CR output from the crank angle sensor 25, a throttle signal TH output from the throttle opening sensor 27, and a water temperature output from the water temperature sensor 29. Based on the signal WT and the intake pressure signal IP output from the intake pressure sensor 21, a set signal SET is generated, and the OCV 139 is controlled to switch the cam to the low speed cam 39 or the high speed cam 41. Then, the injector 140 is controlled to inject fuel, and the spark plug 141 is controlled to ignite at an appropriate timing. In this example, the cam signal CA indicates the top dead center (between the compression stroke and the explosion stroke) detected by the cam sensor 23. However, the cam signal CA may indicate a top dead center between the exhaust stroke and the intake stroke, or may indicate a bottom dead center. In short, any cam signal CA may be used for determining the stroke. The crank signal CR indicates the rotation angle of a crankshaft (not shown). The throttle signal TH indicates the throttle opening detected by the throttle opening sensor 27. The water temperature signal WT indicates the temperature of the cooling water for the engine 7 detected by the water temperature sensor 29. The intake pressure signal IP indicates the intake pressure detected by the intake pressure sensor 21.

The peak hold circuit 162 holds the maximum value of the intake pressure signal IP output from the intake pressure sensor 21. The peak hold circuit 162 is set in response to a high level set signal SET, and is reset in response to a low level set signal (reset signal) SET. As a result, the peak hold circuit 162 samples the intake pressure detected between the exhaust stroke and the intake stroke among the intake pressure detected by the intake pressure sensor 21, and provides it to the microcomputer 161.

(4) Operation Next, the operation of the engine 7, particularly the ECU 16, will be described. First, with reference to FIG. 10, the operation of the microcomputer 161 determining whether the cam should be switched to the low speed cam 39 or the high speed cam 41 will be described.

  The microcomputer 161 detects the crank angle based on the crank signal CR from the crank angle sensor 25 (S1), and determines whether or not the engine 7 has been started (S2). If the engine 7 is not started, the microcomputer 161 waits until the engine 7 is started (NO in S2), and if it is started, the microcomputer 161 proceeds to the following process (YES in S2). When the engine 7 is started, since the hydraulic pressure is not applied to the connecting pin 90, the cam is the low-speed cam 39.

  The microcomputer 161 detects the water temperature based on the water temperature signal WT from the water temperature sensor 29 (S3), and determines whether the water temperature is equal to or higher than a predetermined temperature (S4). If the water temperature is lower than the predetermined temperature, the microcomputer 161 waits until the water temperature reaches the predetermined temperature (NO in S4). If the water temperature is equal to or higher than the predetermined temperature, the microcomputer 161 proceeds to the following process (YES in S4). In this example, the temperature of the cooling water is detected instead of the temperature of the lubricating oil for the engine 7 in order to determine whether or not the valve mechanism is operable. However, the temperature of the lubricating oil is directly detected. Also good.

  The microcomputer 161 calculates the rotational speed of the engine 7 based on the crank signal CR from the crank angle sensor 25 (S5), and detects the throttle opening based on the throttle signal TH from the throttle opening sensor 27 (S5). S6).

  The microcomputer 161 reads the switching determination value corresponding to the calculated rotational speed of the engine 7 and the detected throttle opening with reference to the switching determination value map in the storage area 163 (S7).

  The microcomputer 161 reads the actual cam state from the storage area 166 (S8). Immediately after the engine 7 is started, the actual cam state of the low speed cam 39 is read.

  When the read actual cam state is the low speed cam 39 (YES in S9), the microcomputer 161 determines whether the read switching determination value is equal to or higher than a predetermined high threshold value HTH (S10). When the actual cam state is the high speed cam 41 (NO in S9), it is determined whether or not the read switching determination value is equal to or less than a predetermined low threshold value LTH (S11). The high threshold value HTH is set higher than the low threshold value LTH, thereby providing hysteresis.

  When the actual cam state is the low speed cam 39 and the switching determination value is equal to or higher than the high threshold value HTH (YES in S10), or when the actual cam state is the high speed cam 41, the switching determination value is the low threshold value LTH. If not (NO in S11), the microcomputer 161 sets the requested cam state to the high-speed cam 41 (S12). This indicates that the cam should be switched to the high-speed cam 41 when the actual cam state is the low-speed cam 39, and that the cam should be maintained as it is at the high-speed cam 41 when the actual cam state is the high-speed cam 41.

  On the other hand, when the actual cam state is the high speed cam 41, when the switching determination value is equal to or lower than the low threshold value LTH (YES in S11), or when the actual cam state is the low speed cam 39, the switching determination value is high. When the value is not equal to or greater than the value HTH (NO in S10), the microcomputer 161 sets the requested cam state to the low speed cam 39 (S13). This indicates that the cam should be switched to the low-speed cam 39 when the real cam state is the high-speed cam 41, and that the cam should be maintained as it is at the low-speed cam 39 when the real cam state is the low-speed cam 39. However, cam switching is not yet executed here.

  Next, with reference to FIGS. 11 and 12, the operation of the microcomputer 161 determining whether the cam is actually switched to the low speed cam 39 or the high speed cam 41 will be described.

  The microcomputer 161 detects the crank angle based on the crank signal CR from the crank angle sensor 25 (S21), and determines whether or not the crank angle has reached the start crank angle SC (S22). If the crank angle has not reached the start crank angle SC, the microcomputer 161 waits until it reaches (NO in S22), and if it has reached, proceeds to the following processing (YES in S22).

  The engine 7 has four strokes of intake, compression, explosion (expansion), and exhaust in one cycle. Since the crank (shaft) rotates 180 degrees in each stroke, the crank rotates 720 degrees in one cycle. For example, when the crank angle sensor 25 is installed every 60 degrees, the crank signal CR includes three pulses in each stroke. In this example, the start crank angle SC is set within the exhaust stroke. In order to identify the stroke, not only the crank signal CR but also the cam signal CR is used.

  When the crank angle reaches the start crank angle (YES in S22), the microcomputer 161 sets the set signal SET to the high level and sets the peak hold circuit 162 (S23). When set, the peak hold circuit 162 holds the maximum value of the intake pressure detected by the intake pressure sensor 21.

The microcomputer 161 determines whether or not the crank angle has reached the end crank angle EC (S24). In this example, the end crank angle EC is set within the intake stroke. When the crank angle reaches the end crank angle EC (YES in S24), the microcomputer 161 reads the output of the peak hold circuit 162, that is, the maximum intake pressure (S25), sets the set signal SET to low level, and the peak hold circuit 162. Is reset (S26). As a result, the peak hold circuit 162 samples the intake pressure detected between the exhaust stroke and the intake stroke among the intake pressure detected by the intake pressure sensor 21, and provides it to the microcomputer 161.

  The microcomputer 161 determines whether or not the read maximum intake pressure is equal to or higher than a predetermined value (a value slightly higher than the atmospheric pressure, for example, 110 to 130 KPa) (S27). If the maximum intake pressure is equal to or higher than the predetermined value (YES in S27), the microcomputer 161 determines that the cam is actually switched to the high speed cam 41, and sets the actual cam state to the high speed cam 41 (S28). On the other hand, if the maximum intake pressure is less than the predetermined value (NO in S27), the microcomputer 161 determines that the cam is actually switched to the low speed cam 39, and sets the actual cam state to the low speed cam 39 (S29). .

  As shown in FIG. 12, when the cam is switched to the low speed cam 39, the lift amounts of the exhaust valve 24 and the intake valve 22 are both small and do not overlap each other. That is, the intake valve 22 starts to open after the exhaust valve 24 is closed. On the other hand, when the cam is switched to the high-speed cam 41, the lift amounts of the exhaust valve 24 and the intake valve 22 are both large and overlap each other. That is, the intake valve 22 starts to open before the exhaust valve 24 is closed. Thus, since both valves 22 and 24 are closed at the top dead center between the exhaust stroke and the intake stroke at low speed, the intake pressure hardly exceeds atmospheric pressure, whereas at the high speed, the exhaust stroke and intake stroke. Since the valves 22 and 24 are open at the top dead center between the two, the air-fuel mixture is blown back to the intake port 9 and the intake pressure temporarily exceeds the atmospheric pressure temporarily. For example, the intake pressure rises to 140 kPa. As a result, when the maximum intake pressure held in the peak hold circuit 162 becomes equal to or higher than a predetermined value, it is determined that the cam is actually switched to the high speed cam 41.

  Next, the operation of the microcomputer 161 for switching the cam to the low speed cam 39 or the high speed cam 41 will be described with reference to FIG.

  The microcomputer 161 reads the actual cam state from the storage area 166 (S31) and reads the requested cam state from the storage area 165 (S32). The microcomputer 161 determines whether or not the read actual cam state matches the read requested cam state (S33).

  If the actual cam state does not match the requested cam state (NO in S33), since the cam has not yet been switched as requested, the microcomputer 161 instructs the OCV 139 to switch the cam (S34). In response to this, the OCV 139 applies to the connecting pin 90 to switch the cam from the low-speed cam 39 to the high-speed cam 41 when the requested cam state is the high-speed cam 41 but the actual cam state is the low-speed cam 39. Control hydraulic pressure.

  If the switching failure timer has not been set yet (NO in S35), the microcomputer 161 sets a predetermined time limit in the switching failure timer (S36). This time limit is to limit the time required from when the cam switching command is issued until the actual switching is completed. When the switching failure timer has already been set (YES in S35), when the time limit has already passed (S37), the microcomputer 161 issues an alarm to indicate that a failure has occurred in the variable valve mechanism. Lights up (S38).

  On the other hand, if the actual cam state matches the requested cam state (YES in S33), the cam has already been switched as requested, so the engine 7 is controlled under conditions suitable for the actual lift amount (S39 to S41). . More specifically, when the actual cam state is the low speed cam 39 (YES in S39), the microcomputer 161 refers to the FI map and controls the injector 140 to inject fuel at an amount and timing suitable for the low speed cam 39. In addition, the spark plug 141 is controlled to ignite at a timing suitable for the low speed cam 39 (S40). When the actual cam state is the high speed cam 41 (NO in S39), the microcomputer 161 refers to the FI map, controls the injector 140 to inject fuel at an amount and timing suitable for the high speed cam 41, and the high speed cam 41. The spark plug 141 is controlled so as to ignite at a timing suitable for the operation (S41).

  As shown in FIG. 14, for example, when a command for switching the cam from the low-speed cam 39 to the high-speed cam 41 is issued, the actual switching of the cam is slightly delayed from the command. However, if the actual switching is completed within the time limit from the command, it is determined that the cam is actually switched, and a suitable condition is selected from the FI map accordingly, and the engine 7 is controlled under that condition.

  On the other hand, as shown in FIG. 15, for example, when a command for switching the cam from the low-speed cam 39 to the high-speed cam 41 is issued, but the cam is not actually switched within the time limit from the command, Determined as abnormal.

  As described above, according to the embodiment of the present invention, it is determined that the variable valve mechanism has switched the cam from the low-speed cam 39 to the high-speed cam 41 when the intake pressure detected by the intake pressure sensor 21 exceeds a predetermined value. Further, since the variable valve mechanism determines that the cam has been switched from the high-speed cam 41 to the low-speed cam 39 when the intake pressure detected by the intake pressure sensor 21 is less than a predetermined value, the actual switching of the cam is indirectly performed. Can be detected.

  Further, since the peak hold circuit 162 samples the intake pressure detected during the intake and exhaust strokes of the intake pressure detected by the intake pressure sensor 21, the intake pressure is supplied from the predetermined value to the microcomputer 161. Only the intake pressure within the period during which there is a possibility of increasing the value is extracted, and the cam switching determination accuracy is improved.

  In addition, when it is not determined that the cam has actually been switched after a predetermined time limit has elapsed since the cam switching command was issued, an alarm is lit, so the user immediately recognizes that the variable valve mechanism has failed. can do.

  Further, in the case of a multi-cylinder engine, since one intake pipe is commonly connected to a plurality of intake ports, the intake pressure may interfere with each other between the intake ports. However, since the engine 7 in the above embodiment is a single cylinder, there is no such possibility.

  Although the intake pressure sensor 21 is provided in the intake port 9 in the above embodiment, it may be provided in the intake path leading to the intake valve 22 such as in the intake pipe 10. More specifically, the intake pressure sensor 21 may be provided downstream of the throttle valve and upstream of the intake valve 22.

  Instead of the two types of cams in the above embodiment (low speed cam 39 and high speed cam 41), one type of cam may be used, and the lift amount may be switched by increasing the shift amount of the rocker arm at high speed. . Further, the lift amount of only the intake valve or only the exhaust valve may be switched. Furthermore, the lift amount may be switched in three steps or more. In addition, “≧” and “>” and “≦” and “<” can be interchanged.

  While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

7 Engine 9 Intake port 10 Intake pipe 21 Intake pressure sensor 22 Intake valve 23 Cam sensor 24 Exhaust valve 25 Crank angle sensor 27 Throttle opening sensor 39 Low speed cam 41 High speed cam 89 Actuator 90 Connecting pin 100 Motorcycle 139 OCV
161 Microcomputer 162 Peak hold circuit 701 Cylinder

Claims (6)

When the lift amount of at least one of the intake and exhaust valves is switched to the first lift amount or the second lift amount that is larger than the first lift amount , and the lift amount is the second lift amount, A part of the period during which the exhaust valve is opened and a part of the period during which the intake valve is open are overlapped so that the intake valve starts to open before the exhaust valve is closed, and the lift amount is the first amount A variable valve mechanism that does not overlap a period during which the exhaust valve is open and a period during which the intake valve is open so that the intake valve begins to open after the exhaust valve has been closed when the lift amount is
An intake pressure sensor that is provided in an intake path leading to the intake valve and detects intake pressure;
Sampling means for sampling the intake pressure detected between the exhaust stroke and the intake stroke of the intake pressure detected by the intake pressure sensor;
Switching determination means for determining that the variable valve mechanism has switched the lift amount from the first lift amount to the second lift amount when the intake pressure provided from the sampling means is higher than a predetermined value; equipped with a,
engine. The engine of claim 1, further comprising:
Switching command means for commanding the variable valve mechanism to switch the lift amount;
Failure determination means for determining that the variable valve mechanism is in failure when the switching determination means does not determine that the lift amount has been switched despite the switching instruction means being instructed to switch the lift amount. Provide an engine. The engine according to claim 2 , further comprising:
Provided with a time limit means for setting a predetermined time limit,
The failure judgment means switches the lift amount by the switching judgment means even though the time limit set by the time restriction means has elapsed since the switching instruction means was instructed to switch the lift amount. When it is not determined that the engine has failed, the variable valve mechanism determines that the engine has failed. The engine of claim 1, further comprising:
An engine with a single cylinder. The engine according to claim 1,
The predetermined value is higher than atmospheric pressure, the engine.   A motorcycle comprising the engine according to claim 1.

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