JP4506705B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that performs valve stop control.

  A reciprocating engine (internal combustion engine) installed in an automobile can be operated in a cylinder deactivation mode in which some cylinders are deactivated under driving conditions that do not require a large output in order to save fuel. There is an engine. In many of these engine idle mode operations, a variable valve device is used to reduce the lift (opening / closing) of the intake valves and exhaust valves of each cylinder in order to reduce pumping loss.

  Since the variable valve system that switches the idle cylinder mode can be configured simply, a cam follower rocker that displaces the intake side and exhaust side rocker arms following the cam (intake cam and exhaust cam), Divided into valve drive rockers that drive valves (intake valves and exhaust valves), these cam follower rockers and valve drive rockers are divided into rocker arms that are rotatably supported on the rocker shaft for each intake and exhaust. It is used. Then, the cam displacement from the cam follower rocker is transmitted or cut off to the valve drive rocker through the switching unit. For example, the switching portion that performs this transmission / reception has a structure in which one of the abutting portion and the receiving portion that can be locked to the abutting portion is provided in the cam follower rocker, and the other is provided in the valve drive rocker. Used. The receiving part can be displaced between a position where it abuts against the abutting part and a position where it does not abut. When the receiving part is a position where it abuts against the abutting part, the cam displacement of the intake cam is driven from the cam follower rocker by valve drive. When it is transmitted to the valve through the rocker (transmission mode) and the receiving part is in a position where it does not hit the abutting part, the movement of the abutting part is released and the cam follower rocker is simply swung (pause mode). The cam displacement is prevented from being transmitted to the valve drive rocker (see Patent Document 1).

  By the way, when the intake valve and the exhaust valve are stopped, the valve drive rocker becomes unstable because the cam follower rocker is not supported. Therefore, the split rocker arm supports the valve drive rocker when the valve is stopped. Many cam camshafts have a cam profile (different from intake cams and exhaust cams with cam profiles suitable for intake and exhaust) formed only by the base circle, and the valve drive rocker slides with the cam. A structure is used in which a slipper that can be contacted is provided so that the valve drive rocker is supported by sliding contact between the tip of the slipper and the stop cam when the valve is stopped.

In an SOHC (Single Over Head Camshaft) type engine that uses a single camshaft to drive the intake and exhaust valves, the intake and exhaust camshafts are suspended in order to share these pause cams on the intake and exhaust sides. A cam is provided, and a slipper (a pair) is provided on each intake / exhaust valve drive rocker assembled to an intake rocker shaft on both sides of the camshaft and an exhaust rocker shaft. Specifically, as a pair of slippers protruding from each valve drive rocker, the slipper members are arranged along the width direction on the cam surface of the pause cam, and the end portions of these slipper members are in sliding contact with the cam surface of the pause cam. A structure to be used is used (Patent Document 1).
JP-A-2005-90408

  By the way, since the variable valve operating system has many restrictions such as relying on hydraulic pressure to switch between the transmission mode and the pause mode, the variable valve operating device is provided between the end of the intake valve and the exhaust valve and the valve drive rocker. It is difficult to assemble a device that makes the valve clearance (valve clearance) zero. For this reason, when the valve is stopped, the movement of the valve drive rocker on the intake / exhaust side is often regulated by the stop cam and the slipper while including the valve clearance.

  Therefore, the valve drive rocker (both intake side and exhaust side) is likely to behave as if the rocker shaft flutters to the fulcrum due to vibration from the engine body when the valve is at rest.

  However, the flapping behavior is carried out with a considerable momentum, and there is a problem that a loud sound (noise) is generated when the valve drive rocker comes into contact with the cam surface of the rest cam. Since the engine is required to be quiet, it is required to improve the noise at these parts.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that can reduce the sound (noise) when the valve is stopped.

In order to achieve the above object, a variable valve operating apparatus for an internal combustion engine according to one aspect of the present invention includes:
A camshaft having an intake cam having an intake cam profile, an exhaust cam having an exhaust cam profile, and a rest cam formed only by a base circle, and rotated by a crank output;
An intake rocker shaft arranged in parallel with the camshaft ;
An exhaust rocker shaft disposed in parallel with the camshaft on the opposite side of the camshaft with respect to the intake rocker shaft;
An intake valve driven by the intake cam;
An exhaust valve driven by the exhaust cam;
A boss rotatably supported on the intake rocker shaft, a first valve drive rocker for driving the intake valve, and a rotatable on the intake rocker shaft so as to be displaced following the intake cam An intake rocker arm composed of a first cam follower rocker supported by
A boss rotatably supported by the exhaust rocker shaft, a second valve drive rocker for driving the exhaust valve, and a rotatable to the exhaust rocker shaft so as to be displaced following the exhaust cam An exhaust rocker arm comprising a second cam follower rocker supported by
A transmission mode for transmitting cam displacement from the first and second cam following rockers to the first and second valve driving rockers, and from the first and second cam following rockers to the first and second valve driving rockers. A pause mode that interrupts transmission of cam displacement, and a switching unit that can be turned on and off,
The intake valve and the boss of the first valve drive rocker and the boss of the second valve drive rocker are formed on the boss of the second valve drive rocker, respectively, and when the switching unit is in sliding mode, A pair of slippers that keep the first valve drive rocker and the second valve drive rocker in a predetermined posture so that the exhaust valve is kept closed;
The rest cam is formed with an outer diameter larger than that of the intake cam and the exhaust cam, and the slippers of the first and second valve drive rockers are respectively the first and second valve drive rockers. Leg portions projecting from the boss toward the axis of the camshaft are provided. Each leg portion is formed in a taper shape as it advances in the direction of the cam surface of the pause cam, and a sliding contact that slides on the cam surface of the pause cam is provided at the distal end portion of the pair of slippers. The leg portions and the sliding contact are arranged side by side so as to face each other along the circumferential direction of the cam surface of the pause cam.

  With this configuration, the total length of the slipper is shorter than the arrangement in the width direction of the cam surface, so the lever ratio of the valve drive rocker is changed and the actual clearance generated between the slipper and the rest cam is reduced. The Thus, the impact energy applied from the slipper to the rest cam is reduced.

Furthermore, according to one aspect of the present invention, the slipper formed on the boss of the first valve drive rocker and the slipper formed on the boss of the second valve drive rocker have the same leg and sliding contact with each other. It has a width dimension.

According to the first aspect of the present invention, compared to the structure in which the pair of slippers are arranged in the width direction of the cam surface of the rest cam ( the swing angle of the first and second valve drive rockers is the same), the difference in arrangement and the rest cam The overall length of the slipper is shortened depending on the size of the slipper. For this reason, the lever ratio of the first and second valve drive rockers is changed, so that the actual clearance generated between the pause cam and the first and second valve drive rockers can be set small , and the weight of the intake and exhaust rocker arms Increase can be suppressed.

Therefore, it is possible to fluttering of the slipper during valve rest is reduced, suppressing the impact energy when the slippers abuts the resting cam. As a result, it is possible to reduce the hitting sound (noise) generated when the first and second valve drive rockers strike the pause cam.

In addition, if the length of the slipper is shortened, the weight of the rocker arm is reduced accordingly, and the fluttering noise is further reduced. In addition, the friction can be reduced, and the valve lift can be reproduced exactly as designed, especially at high speeds, resulting in high engine performance .

    According to the invention of claim 2, since the width of the rest cam can be narrowed, the valve train for one cylinder can be narrowed and can be applied to an engine having a small bore. Furthermore, since the rocker arm width can be set narrower by the slipper width and the weight of the rocker arm is reduced, fluttering noise is further reduced. The weight of the valve system can be reduced, reducing friction and making it easier to reproduce the valve lift as designed, especially at high speeds, resulting in high engine performance.

[One Embodiment]
Hereinafter, the present invention will be described based on an embodiment shown in FIGS.

  FIG. 1 is a perspective view of an engine (internal combustion engine), for example, a V-type 6-cylinder reciprocating engine (hereinafter simply referred to as a V-type engine) viewed from the rear, and FIG. 2 is a variable valve operating system for intake and exhaust valves of the engine. FIG. 3 is a plan view of the valve operating device (in the direction of arrow A in FIG. 2), FIG. 4 is a plan view showing various cams of the valve operating device, and FIGS. 9 is a perspective view showing a rocker arm structure on the intake side, FIG. 10 is an exploded perspective view of the structure, and FIG. 11 is a rocker arm structure on the exhaust side. FIG. 12 is an exploded perspective view of the structure, and FIG. 13 is a diagram showing valve characteristics provided by the variable valve operating device. In FIG. 1, Fr indicates the front of the V-type engine.

  In FIG. 1, reference numeral 1 denotes an engine body of a V-type engine. The engine main body 1 has, for example, a V-shaped cylinder block, specifically, a common crankcase portion 2 at the lower portion, and a cylinder having a V-shaped deck cylinder portion 4 in which, for example, three cylinders 3 are distributed at the upper portion. The block 5 and a part such as a cylinder head 6 mounted on the head of each deck cylinder unit 4 are combined. FIG. 1 does not show fine parts such as a head cover and an oil pan. And from each deck cylinder part 4, cylinder head 6, etc., the left and right banks 7a and 7b projecting in a V shape (left and right are determined based on the forward direction) are configured. A piston 8 is reciprocally accommodated in the cylinder 3 of each bank 7a, 7b (shown in FIG. 2), and a crankshaft (not shown) is incorporated in the crankcase portion 2. However, the banks 7a and 7b are offset in the front-rear direction so that connecting rods (not shown) extending from the pistons 8 are arranged side by side on the axis of the crankshaft.

  As shown in FIG. 2, combustion chambers 11 are respectively formed on the lower surface of each cylinder head 6 facing the cylinder 3. In each of these combustion chambers 11, as shown in the figure, two (plural) intake ports 12 a, 12 b and intake ports 12 a, 12 b are opened and closed, located inside the banks 7 a, 7 b. Two intake valves 13a and 13b are provided. Similarly, two exhaust ports 14a and 14b and two exhaust valves 15a and 15b for opening and closing the exhaust ports 14a and 14b are provided on the outer side, and combustion air is sucked from the inner side of the bank. In this structure, the burned gas is discharged from the outside of the bank. The intake valves 13a and 13b and the exhaust valves 15a and 15b all have a normally closed structure that is biased in the closing direction by a valve spring (not shown).

  The cylinder heads 6 of the left and right banks 7a and 7b are provided with SOHC (Single Over Head Camshaft) type valve operating systems 17, respectively. Among these, the valve system 17a in the left bank includes a rocker arm module 18 for intake that can be switched to a normal (low speed) mode, a high speed mode, and a cylinder deactivation mode (mode for deactivating the cylinder) (normal mode switching), A variable valve device 16a is used in combination with an exhaust rocker arm module 19 that can be switched between a (low speed) mode and a non-cylinder mode (mode in which the cylinder is deactivated). The right valve system 17b includes an intake rocker arm module 20 that can be switched between a normal (low speed) mode and a high speed mode (two-mode switching), and an exhaust valve mechanism 21 that is only in the normal (low speed) mode. A variable valve device 16b in combination is used.

  FIG. 2 shows a variable valve device 16a (both intake and exhaust) for one cylinder of the valve train 17a mounted in the left bank 7a (a view from the rear of the engine). ). 9 shows a view of the rocker arm module 18 from the inside, FIG. 10 shows an exploded view of the module 18, and FIG. 11 shows a view of the rocker arm module 19 from the inside. FIG. 12 is an exploded view of the module 19.

  2 and 3, reference numeral 25 denotes a rotatable camshaft disposed along the longitudinal direction of the cylinder head 6 at the top center of the combustion chamber 11, and 26 denotes the camshaft. An intake rocker shaft 27 is disposed (fixed) substantially in parallel with the camshaft 25 on the inner side of the bank 25, and 27 is disposed (fixed) substantially in parallel with the camshaft 25 on the opposite side (outside of the bank). The exhaust rocker shaft is shown. The rocker shafts 26 and 27 are both arranged on the upper side of the camshaft 25.

  Among these, in the rocker shaft 27, an oil passage 27 a for changing cylinder rest is formed along the axial direction. Within the rocker shaft 26, an oil passage 26a for changing cylinders connected to the end of the oil passage 27a and an oil passage 26b for high speed switching are formed along the axial direction.

  The camshaft 25 is a component that is rotationally driven by a crank output. For example, as shown in FIGS. 2 and 4, the shaft portion of the camshaft 25 disposed above the combustion chamber 11 includes a high-speed intake cam 30 and a liftless cam (the pause cam of the present application) in order from the rear side of the engine. 31), an exhaust cam 32, and a low-speed intake cam 33 are formed. The low-speed intake cam 33 has a cam profile set to an opening / closing timing and a valve lift amount suitable for low-speed operation of the engine, and the high-speed intake cam 30 is an opening / closing timing and valve lift amount suitable for high-speed operation of the engine. It has a cam profile that is set (larger than the low-speed cam 33). The liftless cam 31 has a circular cam profile formed only by a base circle having the same radius larger than the base circle of the intake cams 30 and 33 and the exhaust cam 32. Of course, the exhaust cam 32 has a cam profile of opening / closing timing and valve lift amount suitable for discharging combustion gas.

  The intake rocker arm module 18 uses a split rocker arm 18a as shown in FIG. 2, FIG. 9 and FIG. This includes a valve driving rocker 35 (corresponding to the first valve driving rocker of the present application) for driving the intake valves 13a, 13b, and low and high speed cam following rockers 60, 70 (following the intake cams 30, 33). Both of them are divided into the structure corresponding to the first cam follower rocker of the present application).

  Specifically, as shown in FIGS. 2 and 10, the valve drive rocker 35 includes a cylindrical rocker shaft support boss 36 and intake valves 13 a and 13 b (both diameter direction) from both ends of the boss 36. A pair of (two or more) rocker arm portions 37 extending in the direction, an adjusting screw portion 38 (abutting portion) assembled to the distal end portion of the rocker arm portion 37, and each base portion (base end) of the arm portion 37 Switching operation sections 40a and 40b for mode switching provided in the section).

  The pair of rocker arm portions 37 are arranged in parallel in the axial direction of the boss 36. As shown in FIG. 2, the boss 36 is rotatably fitted over the rocker shaft 26 corresponding to the point from the point where the intake cam 30 (for high speed) is located to the point where the intake cam 33 (for low speed) is located. The adjusting screw portion 38 at the tip of each rocker arm portion 37 is positioned at the upper end (valve stem end) of each of the intake valves 13a and 13b. In other words, when the valve drive rocker 35 swings about the rocker shaft 26 as a fulcrum, the end of the adjusting screw portion 38 contacts the valve stem end to drive the intake valves 13a and 13b.

A piston type is used for each of the switching operation portions 40a and 40b disposed at both ends of the boss 36. When these explaining switching operation portion 40a which is arranged on the side of the intake cam 33 (low-speed), 5, 9 and 10 of 43, for example the root portion of the intake cam 33 side of the arm portion 37 (proximal end Part). The cylinder 43 has a vertical shape extending along the diameter direction of the rocker shaft 26. A window portion 44 is formed in the lower portion of the front surface of the cylinder 43 (the surface on the camshaft 25 side).
A through hole 45 (shown only in FIG. 5) having a smaller diameter than the cylinder 43 is formed from the bottom surface of the cylinder 43 to the inner surface 36a (bearing surface) of the boss 36 just below the cylinder 43. A piston 46 (corresponding to the receiving portion of the present application) is accommodated in the cylinder 43 together with a compression spring 47 that urges the piston 46 to the bottom surface of the cylinder 43 (only FIG. 5 is shown). Accordingly, the window portion 44 of the cylinder 43 is normally closed by the lower outer peripheral surface of the piston 46, and when the piston 46 is lifted, the piston 46 is retracted from the window portion 44 so that the window portion 44 is opened. It is.
A pin 48 is slidably accommodated in the through hole 45 as shown in FIG. As shown in FIG. 5, the lower end opening of the through hole 45 is a branch passage 49 branched from the oil passage 26a, more specifically, a branch passage 49 branched from the oil passage 26a in the radial direction and opened to the outer peripheral surface of the rocker shaft 26. When the oil pressure is applied to the pin 48 from the oil passage 26a, the piston 46 that has closed the window 44 as shown by the two-dot chain line in FIG. Driving in the direction to be applied, that is, the window 44 is opened.

  As with the switching operation portion 40a, the switching operation portion 40b disposed on the intake cam 30 (for high speed) side has a cylindrical cylinder at the base portion of the arm portion 37 as shown in FIGS. A structure in which 51 is formed is used. The cylinder 51 extends to the inner surface 36a of the boss 36 in order to earn a stroke amount. Therefore, a through hole 52 communicating with the cylinder 51 in series is formed in the rocker shaft 26 portion immediately below the cylinder 51. The through hole 52 has a smaller diameter than the cylinder 51. Further, unlike the switching operation portion 40a, as shown in FIG. 6, a window portion 50 is formed in the upper front portion of the cylinder 51, and a piston 53 (corresponding to the receiving portion of the present application) is provided in the cylinder 51. The piston 53 is accommodated together with a compression spring 54 that biases the bottom surface of the cylinder 51. The piston 53 is thin enough to fit in the lower cylinder portion from the window portion 50. In contrast to the switching operation portion 40a, the opening of the window portion 50 of the cylinder 51 is normally open. When the piston 53 is raised, the outer peripheral surface of the piston 53 is closed. A pin 55 is slidably accommodated in the through hole 52. As shown in FIG. 6, the lower end portion of the through hole 52 intersects and communicates with a part of the oil passage 26b, and when hydraulic pressure is applied from the oil passage 26b to the pin 55, the pin 55 moves upward. 6, the piston 53 is driven in a direction to close the window portion 50, that is, the window portion 50 is closed.

  As shown in FIGS. 10 and 11, a pair of cutout portions 57 are formed at the opening edges of the both ends of the boss 36. The notch portion 57 is a part of the peripheral wall that forms the end of the boss, for example, directly below the cylinders 43, 51, through the front of the boss 36 (on the side opposite to the arm portion 37) and to the root portion of the arm portion 37. The circumferential part that reaches is continuously cut out.

  The high-speed cam follower rocker 70 is adjacent to the end of the boss 36 (valve drive rocker) on the intake cam 30 (for high speed) side, as shown in FIGS. 2, 3, 6, 9 and 10. It is a part to be arranged. The cam follower rocker 70 includes a cylindrical rocker shaft support boss 71 that is rotatably inserted into the rocker shaft 26 adjacent to the end of the boss 36, and an intake cam 30 that is one end side from both sides of the boss 71. A pair of roller support pieces 72 (roller yoke) projecting linearly directly above (for high speed), a rotatable roller 73 (rolling contact) supported between the tip portions of the roller support piece 72, and a boss 71 has an abutting portion 79 (corresponding to the abutting portion of the present application) formed on the peripheral wall of 71. Accordingly, the cam follower rocker 70 has a structure in which the roller 73 is provided on one end side and the abutting portion 79 is provided on the other end side. Of these, the roller 73 is in rolling contact with the cam surface of the intake cam 30. When the cam shaft 25 rotates, the cam follower rocker 70 swings while following the cam displacement of the intake cam 30 with the boss 71 as a fulcrum.

Further, at the end of the boss 71 adjacent to the boss portion 36 (valve drive rocker), a notch 76 is formed by notching a predetermined distance from the boss end as shown in FIGS. The cutout portion 76 is formed by cutting out the peripheral wall portion on the opposite side to the boss portion 36 (valve drive rocker). For example, a structure in which a circumferential portion from the upper side of the boss 71 to the front portion of the boss 71 (the side opposite to the roller 73) is continuously cut out is used. The notch 76 at the end of the boss 71 and the notch 57 at the end of the boss 36, and the edge 36 b remaining at the opening end of the boss 36 and the edge 71 b remaining at the opening end of the boss 71 complement each other. It fits in.
The notches 71 and 57 are defined up to a region where a required movement of the cam follower rocker 70 described later is allowed. Due to the fitting of the irregularities, the edge 36 b at the end of the boss 36 and the edge 71 b at the end of the boss 71 are wrapped with respect to the axial direction of the rocker shaft 26 on the outer peripheral surface of the rocker shaft 26.
The abutting portion 79 is disposed on the edge portion 71b of the boss 71, and the window portion 50, the cylinder 51, the piston 53, and the compression spring 54 are disposed on the edge portion 36b. The abutting portion 79 and the piston 53 are positioned so as to face each other when the edge portion 36b and the edge portion 71b are wrapped, and the periphery of the rocker shaft 26 of the edge portions 71b and 36b provided by this wrapping is provided. 9 and 10, the abutting portion 79 of the boss 71 and the window portion 50 in the boss 36 are opposed to each other using the side-by-side direction.

  Of the roller support piece 72, the support piece arranged nearer to the boss 36 (inner side) is arranged at a point substantially facing the abutting portion 79, and both the roller support piece 72 and the abutting portion 79 on one side are arranged. The windows 50 are arranged in a straight line. As shown in FIGS. 9 and 10, a wing portion 74 is provided on the outer peripheral surface of the boss 71 so as to extend from the abutting portion 79 to the roller support piece 72 on the inner side (near the boss 36). The wing portion 74 is formed by a rib 78 that continuously connects the abutting portion 79 to the roller support piece 72 in a straight line.

  The abutting portion 79 is formed so that the horizontal wall at the front end of the rib 78 can enter and exit from the inside and outside of the window portion 50, so that the abutting portion 79 normally passes through the window portion 50 through the cylinder 51. When the window part 50 is closed by the piston 53, the abutting part 79 makes contact with the piston 53 exposed from the window part 50. That is, whether the displacement of the high-speed intake cam 30 from the cam follower rocker 70 is transmitted to the valve drive rocker 35 (transmission mode) or not (whether it is transmitted) depending on whether the abutting portion 79 swings or abuts against the piston 53 ( A switching mechanism 79a (corresponding to the switching unit of the present application) capable of switching the (pause mode) is configured.

  A receiving seat 75 for installing a pusher 70a (partially shown by a two-dot chain line in FIG. 6) for pressing the roller 73 against the intake cam 30 is formed on the front end side of the outer roller support piece 72.

The low-speed cam follower rocker 60 is a component that is disposed adjacent to the end of the boss 36 on the side of the intake cam 33 (for low speed) as shown in FIGS. 2, 3, 9, and 10. . The cam follower rocker 60 is structurally the same as the cam follower rocker 70 on the high speed side described above, except that the cam follower rocker 70 is the opposite. Therefore, the description of each part of the cam follower rocker 60, in place of each part of the code 71 to 79 of the preceding cam follower rocker 70, at the same site, a reference numeral 61 to 69 having different numbers of second digit Omitted .

  Of course, the abutting portion 69 is formed in a shape that allows the inside and outside of the window portion 44 to enter and exit. As a result, as shown in FIG. 5, when the cam follower rocker 60 is in a normal state, the abutting portion 69 abuts against the piston 46 closing the window 44, and the piston 46 opens the window 44. The abutting portion 69 goes in and out of the cylinder 43 through the window portion 44. In other words, whether the displacement of the low-speed intake cam 33 from the cam follower rocker 60 is input to the valve drive rocker 35 or the input is stopped depending on whether the abutting portion 69 hits the piston 46 or is swung. A switching mechanism 69a (corresponding to the switching unit of the present application) capable of switching is configured.

  On the other hand, the exhaust rocker arm module 19 includes a cam follower rocker 80 (corresponding to the second cam follower rocker of the present application) that follows the exhaust cam 32 as shown in FIGS. 2, 7, 11, and 12. A split rocker arm 18b divided into a valve drive rocker 90 (corresponding to the second valve drive rocker of the present application) for driving the exhaust valves 15a and 15b is used.

  Among these, the cam follower rocker 80 includes a cylindrical rocker shaft support boss 81 that is rotatably inserted into a rocker shaft 27 portion corresponding to the exhaust cam 32, and the exhaust cam 32 from both ends of the boss 81. A structure having a U-shaped roller support piece 82 projecting linearly directly above, a rotatable roller 83 supported between the tip portions of the roller support piece 82, and a wing portion 84 formed on the boss 81. Is used. The roller 83 is in rolling contact with the cam surface of the exhaust cam 32. Thus, when the cam shaft 25 rotates, the cam follower rocker 80 rotates around the boss 81, that is, swings while following the displacement of the exhaust cam 25. The cam follower rocker 80 is pressed against the exhaust cam 32 by the urging force of a pusher 80a (partially shown by a two-dot chain line in FIG. 7) input from a receiving seat 85 formed on the roller support piece 82.

The wing portion 84 is formed of a rib 86 that projects from the center of the outer surface of the boss 81 in the width direction. The rib 86 extends from the rear end of the roller support piece 82 to the top of the boss 81 along the circumferential direction of the boss 81. An abutting portion 89 having a shape projecting forward is formed at the tip of the rib 86 .

  As shown in FIGS. 2, 11 and 12, the valve drive rocker 90 includes a portal rocker arm portion 91 disposed on both sides of the boss 81 (cam follower rocker 80), and a mode switching operation portion 98. The structure which combined with is used.

  That is, the rocker arm portion 91 has a pair of cylindrical rocker shaft supporting bosses 92 that are rotatably fitted to the rocker shaft 27 portions on both sides of the boss 81 (cam follower rocker 80) at one end. The other end portion has an arm portion 93 extending linearly from the boss 92 toward the exhaust valves 15a and 15b. An adjusting screw portion 94 that forms the distal end portion of each arm portion 93 is disposed at the upper end (valve stem end) of each of the exhaust valves 15a and 15b. And between the front-end | tip parts of the arm parts 93 and 93 is connected by the plate-shaped connection arm 95, for example, and it is set as the portal shape. When the valve drive rocker 90 swings about the rocker shaft 27 as a fulcrum, the plurality of exhaust valves 15a and 15b are driven.

  The switching operation part 98 is provided in the connection arm 95 as shown in FIGS. A piston type as shown in FIG.

  Referring to FIG. 7, reference numeral 99 denotes a vertical cylinder. The cylinder 99 is formed so as to protrude upward from the center of the connecting arm 95. The cylinder 99 is inclined backward in a direction away from the rocker shaft 27. A window portion 100 is formed in the lower portion of the front surface (the surface on the camshaft 25 side) of the cylinder 99. A through hole 101 having a smaller diameter than that of the cylinder 99 is formed from the bottom surface of the cylinder 99 to the inside of the arm portion immediately below the cylinder 99.

In the cylinder 99, a piston 102 (corresponding to a receiving portion of the present application) is accommodated together with a compression spring 103 that urges the piston 102 toward the bottom surface of the cylinder 99. That is, normally, the window portion 100 of the cylinder 99 is blocked by the outer peripheral surface of the piston 102, and when the piston 102 is raised, the piston 102 is retracted from the window portion 100 and the window portion 100 is opened. . A pin 104 is slidably accommodated in the through hole 101. The lower end opening of the through hole 101 communicates with a relay path 105 formed inside the connecting arm 95 as shown in FIGS. 3 and 7. The relay path 105 opens on the inner surface of the boss 92 through a relay path 106 formed inside the arm portion 93.
Further, the relay path 106 communicates with a branch path 107 (shown only in FIG. 7) branched from the oil path 27a, more specifically, a branch path 107 branched in a radial direction from the oil path 27a and opened to the outer peripheral surface of the rocker shaft 27. When oil pressure is applied to the pin 104 from the oil passage 27a, the piston 104 that has closed the window 100 as shown by a two-dot chain line in FIG. Driving, that is, the window 100 is opened.

  Immediately before this window portion 100, the abutting portion 89 of the cam follower rocker 80 is positioned. As shown in FIG. 7, the abutting portion 89 is formed in a shape that can enter and exit the window portion 100. Thus, in a normal state, the abutting portion 89 abuts against the piston 102 blocking the window portion 100, and when the window portion 100 is opened, the abutting portion 89 enters and exits the cylinder 99 through the window portion 100. I have to do it. That is, whether the displacement of the exhaust cam 32 from the cam follower rocker 80 is transmitted to the valve drive rocker 90 (transmission mode) or not (pause) depending on whether the abutting portion 89 abuts on the piston 102 or swings idle. A switching mechanism 97 (corresponding to the switching unit of the present application) capable of switching the (mode) is configured.

On the other hand, as shown in FIGS. 3 and 8 to 12, the parts corresponding to the liftless cam 31 of the boss 36 (valve drive rocker 35) and the boss 92 (valve drive rocker 90) arranged in parallel are respectively Slippers 41 and 96 are provided. The slippers 41, 96 will be described. The slippers 41, 96 have leg portions 41a, 96a projecting between the bosses 36, 92 from the outer peripheral surface portions (front portions) of the bosses 36, 92 facing each other. The tip portions of the leg portions 41a and 96a are connected to the cam surface 31a (outer peripheral surface) of the liftless cam 31 (between the bosses 36 and 92), more specifically from both sides of the camshaft 25 as shown in FIG. Projecting obliquely downward toward cam surface portions on both sides in the circumferential direction across the axis O of the shaft 25.
The end portions of the leg portions 41a and 96a are formed of wear-resistant members as sliding contact portions that are in sliding contact with the cam surfaces 31a on both sides in the circumferential direction with the axis O of the liftless cam 31 as a boundary. Sliding contacts 41b and 96b are provided. These sliding member 41b, 96b is, face each other in the circumferential direction of the cam surface 31a (facing) position is determined as, the sliding member 41b, 96b and the leg portion 41a, a 96a, circumferential on the cam surface of the lift-less cam 31 It arrange | positions so that it may align along a direction (parallel arrangement | positioning in the circumferential direction).
Thus, a pair of suction / exhaust slippers 41, 96 whose tip is slidable in contact with the cam surface 31a of the liftless cam 31 are configured. In particular, as shown in FIGS. 4, 10, and 12, the pair of slippers 41, 96 sets the width dimension X (the dimension in the same direction as the width direction of the liftless cam 31) of each tip to the same dimension. Here, a structure is used in which the leg portions 41a, 96a and the sliding contactors 41b, 96b are set to have the same width dimension and are directly opposed in the circumferential direction of the liftless cam 31. A necessary cam width of the liftless cam 31 is narrower than that of the slippers 41 and 96.
The protruding lengths of the pair of slippers 41 and 96 are such that when the intake valves 13a and 13b and the exhaust valves 15a and 15b are closed, the sliding contacts 41b and 96b are cams of the liftless cam 31 on both sides of the axis O. have been set to the face 31a and capable of abutting dimensions, at each slipper 41,96, when the valve drive rocker 35 and the valve drive rocker 90 does not work transfer, the entire valve drive rocker 35 and the valve drive rocker 90 However, using the reaction force of the valve springs (not shown) of the intake valves 13a and 13b and the exhaust valves 15a and 15b, the posture of the valve closed state (the intake valves 13a and 13b and the exhaust valves 15a and 15b) is maintained as it is. It is supposed to be.

  On the other hand, the oil passage 27a of the rocker shaft 26 on the exhaust side is formed by a hydraulic pressure supply unit (oil pump or the like) via an oil control valve 120 (hereinafter referred to as OCV 120) for changing cylinder rest as shown in FIG. Connected: not shown). The oil passage 26b of the rocker shaft 26 on the intake side is connected to a hydraulic pressure supply unit (formed by an oil pump or the like: not shown) via an oil control valve 121 (hereinafter referred to as OCV 121) for high speed switching. Yes. The OCVs 120 and 121 of the two hydraulic supply systems are both connected to a control unit 122 (for example, constituted by a microcomputer). For example, according to a map set in advance according to the driving state of the vehicle, the control unit 122 “closes” both the OCVs 120 and 121 in the low speed mode, and “opens” only the OCV 121 in the high speed mode. In the non-cylinder mode, a function is set in which only the OCV 120 is “open”.

  Such a structure is adopted for each cylinder 3 of the left bank 7a. That is, in the intake system of the left bank 7a, three-stage switching can be performed: valve drive by the high-speed intake cam 30, valve drive by the low-speed cam 33, and non-valve drive. In the exhaust system, valve drive by the exhaust cam 32 and non-drive Two-stage switching of valve drive can be performed.

  Each rocker arm module 20 of the valve train 17b of the right bank 7b has a structure in which the mechanism and portions that are non-valve driven are removed from the intake rocker arm module 18 of the left bank 7a. Although not shown in the figure, the low-speed side switching structure (mainly the switching operation portion 40a and the cam follower rocker 60) is omitted, and the valve drive rocker 35 is always directly connected to the low-speed intake cam 33. A driven structure is used. Thus, only the switching structure on the high speed side is left, and the two-stage switching between the low speed mode and the high speed mode can be performed. On the exhaust side, the exhaust rocker arm module 19 of the left bank 7a, excluding the non-valve drive mechanism and parts, that is, only the valve drive rocker 90 is always driven directly by the exhaust cam 32. The structure is used. Further, the right bank 7b employs a structure in which the oil passages 26a, 27a for switching the cylinder rest mode are omitted and only the oil passage 26b is left. That is, the right bank 7b has a structure in which the valve drive by the high-speed intake cam 30 and the valve drive by the low-speed cam 33 can be switched in two stages in the intake system, and only the valve drive by the exhaust cam 32 can be performed in the exhaust system. .

  With the valve trains 17a and 17b of the left and right banks 7a and 7b, an operation in which some cylinders (three cylinders of the left bank 7a) are stopped can be performed.

  That is, the operation of the valve train 17 will be described with reference to FIGS. 5 to 8. It is assumed that a command to execute the low speed mode is given to the control unit 122 according to the traveling state of the automobile.

  Then, the OCV 120 and 121 are both closed by the control unit 122. That is, the oil passages 26a, 26b, and 27a are all in a state where the hydraulic pressure from the hydraulic pressure supply system does not act. Thereby, as shown by the solid line in FIG. 5, the window portion 44 of the switching operation portion 40 a (intake air) of the left bank 7 a is blocked by the piston 46 (by the elastic force of the compression spring 47). Further, as shown by the solid line in FIG. 6, the window portion 50 of the switching operation portion 40 b (intake) is opened (due to the elastic force of the compression spring 54). Further, as shown in FIG. 7, the window portion 100 of the switching operation portion 98 (exhaust) of the left bank 7a is blocked by the piston 102 (by the elastic force of the compression spring 103).

  Then, on the intake side of the left bank 7a, the cam follower rocker 70 (high speed) is driven to swing while being idle. At the same time, the cam follower rocker 60 (low speed) is driven to swing while abutting against the piston 46. On the exhaust side of the left bank 7a, the cam follower rocker 80 is driven to swing while abutting against the piston 102.

  Thereby, on the intake side, the displacement of the intake cam 33 (for low speed) transmitted from the cam follower rocker 60 is transmitted from the valve drive rocker 35 to the stem ends of the pair of intake valves 13a and 13b via the pair of rocker arm portions 37. The intake valves 13a and 13b are driven. On the exhaust side, the displacement of the exhaust cam 32 transmitted from the cam follower rocker 80 is transmitted from the connecting arm 95 of the valve drive rocker 90 to the stem ends of the pair of exhaust valves 15a and 15b via the pair of arm portions 93. The exhaust valves 15a and 15b are driven.

  In the variable valve gear 20 of the right bank 7b, the cam follower rocker (high speed) is accompanied by the idling of the cam follower rocker (high speed), so that only the displacement of the low speed intake cam transmitted to the valve drive rocker is transferred to the pair of intake valves. Then, the intake valve is driven. Further, in the exhaust-side valve gear 21, a displacement of an exhaust cam (not shown) directly passes through a pair of arm portions (not shown) via a valve drive rocker (not shown). It is transmitted to a valve (not shown), and the exhaust valve is driven.

  As a result, the V-type engine is operated in the low-speed mode provided by the combination of the low-speed cam and the exhaust cam in the diagram of FIG. That is, the engine performance required for normal travel is output.

  Further, when a command to execute the high-speed mode is given by the control unit 122 according to the running state of the automobile, the control unit 122 performs control to open only the OCV 121 for high-speed switching. As a result, the hydraulic pressure acts only on the oil passage 26b.

  Then, hydraulic pressure is applied to the pin 55 of the switching operation part 40b (intake side) of the left bank 7a. As a result, the window portion 50 is blocked by the piston 53 driven upward by the pin 55 as indicated by a two-dot chain line in FIG. Note that the exhaust bank side of the left bank 7a continues to be in a state where the window portion 100 of the switching operation portion 98 is blocked by the piston 102.

  Thereby, the cam follower rocker 70 on the intake side is driven to swing while abutting against the piston 53 as shown by a two-dot chain line in FIG.

Here, the window portion 44 of the switching operation portion 40a is in a state of being blocked by the piston 46, but the outer shape of the high-speed intake cam 30 is set larger than that of the low-speed intake cam 33. Only the cam displacement of the intake cam 30 (for high speed) transmitted from the cam follower rocker 70 is transmitted from the valve drive rocker 35 to the pair of intake valves 13a and 13b via the pair of rocker arm portions 37. That is, the intake valves 13a and 13b are driven by the high-speed intake cam 30. The exhaust valves 15a and 15b continue to be driven by a path in which the displacement of the previous exhaust cam 32 is transmitted from the cam follower rocker 80 to the connecting arm 95 of the valve drive rocker 90. In the variable valve gear 20 of the right bank 7b, Similarly to the left bank 7a, the displacement of the intake cam (for high speed) transmitted from the cam follower rocker (not shown) passes from the valve drive rocker (not shown) through a pair of rocker arm portions (not shown) to a pair of intake valves ( The intake valve is driven by being transmitted to (not shown). The valve gear 21 of the right bank 7b continues to drive a pair of exhaust valves (not shown) directly by a valve drive rocker (not shown).

  As a result, the V-type engine is operated in the high speed mode provided by the combination of the high speed cam and the exhaust cam in the diagram of FIG. That is, it switches to the driving | operation which outputs high engine performance.

  Further, when the control unit 122 gives a command to execute the idle cylinder mode according to the traveling state of the automobile, the controller 122 performs control to open only the idle cylinder OCV 120. Thereby, the hydraulic pressure acts on the oil passages 26a, 27a.

  Then, on the intake side of the left bank 7a, hydraulic pressure is applied to the pin 48, and the pin 48 is driven upward. Thereby, the piston 46 of the switching operation part 40a is driven upward, and the window part 44 is opened as shown by a two-dot chain line in FIG. Further, since the hydraulic pressure is not applied to the switching operation portion 40b, the window portion 50 continues to be opened as shown in FIG. Even on the exhaust side, the piston 104 of the switching operation unit 98 is driven upward by the pin 104 being pushed up. Thereby, the window part 100 of the switching operation part 98 is open | released.

  Each cam follower rocker 60 (intake: low speed), cam follower rocker 70 (intake: high speed), and cam follower rocker 80 (exhaust) in the left bank 7a are driven to swing while being swung, and the valve drive rocker 35 is driven. , 90 (intake and exhaust), the driving force for driving the valve is not transmitted. Accordingly, as shown in FIG. 8, the sliding contacts 41 b and 96 b of the slippers 41 and 96 of the valve drive rockers 35 and 90 continue to be in sliding contact with the circular cam surface (outer peripheral surface) of the liftless cam 31. Both the intake valves 13a and 13b and the exhaust valves 15a and 15b are kept closed. The cam follower lockers 60, 70, 80 are continuously pressed against the cam surface by the pushers 60a, 70a, 80a.

  Due to the disconnection between the cam follower lockers 60, 70, 80 and the valve drive rockers 35, 90, the lift (opening / closing) of the intake valves 13a, 13b and the exhaust valves 15a, 15b in the left bank 7a is stopped (stopped).

  At this time, the variable valve gear 20 for intake and the valve gear 21 for exhaust in the right bank 7b continue to transmit the displacement of the low-speed intake cam to the intake valve, as in the low-speed mode. Since the cam displacement continues to be transmitted to the exhaust valve, the cylinder is switched to the cylinder deactivation mode in which some cylinders (the cylinders in the left bank 7a) are deactivated.

  When such a valve is at rest, a valve clearance CL1 between the valve stem end (valve end portion) and the valve drive rocker 35, 90 as shown in FIG. 8 allows the thermal expansion of the valve stem to escape as shown in FIG. , CL2 (valve clearance: shown in FIG. 8) exists, the valve drive rockers 35 and 90 receive vibrations from the engine body 1 and move around the rocker shafts 26 and 27 (flutter). Behavior is likely to occur.

  At this time, the pair of slippers 41, 96 protruding from both sides of the liftless cam 31 are arranged in parallel along the circumferential direction of the cam surface 31a of the liftless cam 31, as shown in FIGS. Therefore, the momentum of the flapping valve drive rockers 35 and 90 can be suppressed.

In other words, the structure in which the pair of suction / exhaust slippers 41, 96 are arranged along the circumferential direction of the cam surface 31a of the lift cam 31 is a pair of slippers protruding from the valve drive rockers 35, 90 arranged with the same swing angle and the same layout. Compared to the structure in which the liftless cams 31 are arranged in the width direction (cam shaft center direction) of the cam surface 31a of the liftless cam 31, due to the difference in the way the slippers 41, 96 are arranged, the outer diameter of the liftless cam 31 is the intake cam 30, 33 and the exhaust cam 32, and the length dimensions of the slippers 41 and 96 are shortened.
At this time, as shown in FIG. 8, the distance from the tip of the valve drive rocker 35 to the axis of the rocker shaft 26 is “C”, and the distance from the axis of the rocker shaft 26 to the adjusting screw 38 is “D”. When the distance from the tip of the valve drive rocker 90 to the axis of the rocker shaft 27 is “B” and the distance from the axis of the rocker shaft 27 to the adjusting screw portion 94 is “A”, the distances B and C are Since it becomes shorter, the lever ratios (A: B, D: C) of the valve drive rockers 35 and 90 change accordingly. As a result , the lever ratio is set such that the actual clearances CL3 and CL4 generated between the end portions of the slippers 41 and 96 and the liftless cam 31 are reduced.

  Here, since the impact energy applied to the liftless cam 31 from the slippers 41, 96 is proportional to the square of the distance, the impact energy applied to the liftless cam 31 from the slippers 41, 96 is reduced. As a result, the slipper 41 , 96 flutter can be suppressed.

  Therefore, it is possible to reduce the noise (noise) generated when the valve drive rockers 35 and 90 strike (but abut) the liftless cam 31 when the valve is at rest, and the engine noise can be reduced. Moreover, since the weights of the valve drive rockers 35 and 90 are reduced by the reduction in the length of the slippers 41 and 96, the valve drive rockers 35 and 90 are easy to move, and the valve operating characteristics can be improved.

  In particular, by using the structure in which the tip ends of the slippers 41 and 96 have the same width dimension X and are arranged along the circumferential direction of the cam surface 31a, the liftless cam 31 required to receive the slippers 41 and 96 is used. The cam width can be small. By this narrowing, the liftless cam 31 can be easily arranged together with other cams even in the SOHC type valve operating system 17 with many restrictions.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in one embodiment, each slipper arranged in parallel along the circumferential direction of the liftless cam uses a structure in which the entire width is set from the tip portion to the root portion. The same effect can be obtained even when a slipper having the same width dimension only at the tip portion contacting the cam surface of the les cam is used.
In one embodiment, the cam follower rocker is provided with an abutment portion, and the valve drive rocker is provided with a piston. On the contrary, the cam follower rocker is provided with a piston and the valve drive rocker is provided with an abutment portion. It doesn't matter.
Further, in the above-described embodiment, the example in which the present invention is applied to the V-type engine has been described .

The perspective view which shows the engine carrying the variable valve apparatus which concerns on one Embodiment of this invention. The perspective view which shows the whole variable valve apparatus of both the intake and exhaust for 1 cylinder currently mounted in the left bank of the same engine. The top view seen from the A arrow in FIG. The top view which shows the layout of the various cams of a cam shaft. FIG. 4 is a cross-sectional view of the intake side (low speed) variable valve operating apparatus as seen from the direction of arrow B in FIG. 3. Sectional drawing of the variable valve apparatus by the side of intake (high speed) seen from C arrow in FIG. Sectional drawing of the variable valve apparatus by the side of the exhaust seen from D arrow in FIG. FIG. 4 is a cross-sectional view around a liftless cam as viewed from the direction of arrow E in FIG. The perspective view which shows the arm rocker structure by the side of intake. The perspective view which decomposed | disassembled the structure into the cam follower rocker and the valve drive rocker. The perspective view which shows the arm rocker structure by the side of exhaust. The perspective view which decomposed | disassembled the structure into the cam follower rocker and the valve drive rocker. The diagram for demonstrating the variable of the various valve lifts which a variable valve apparatus brings.

Explanation of symbols

13a, 13b ... intake valve, 15a, 15b ... exhaust valve, 18a ... intake rocker arm, 18b ... exhaust rocker arm, 25 ... camshaft, 26 ... intake rocker shaft, 27 ... exhaust rocker shaft, 30, 33 ... intake Cam, 31 ... Pause cam (liftless cam), 31a ... Cam surface, 32 ... Exhaust cam, 35 ... First valve drive rocker, 36, 92 ... Boss, 41, 96 ... Slipper, 41a, 96a ... Leg, 41b 96b, sliding contact, 60, 70, first cam follower rocker, 69a, 79a, 97 ... switching part (switching mechanism), 80 ... second cam follower rocker, 90 ... second valve drive rocker.

Claims (2)

A camshaft having an intake cam having an intake cam profile, an exhaust cam having an exhaust cam profile, and a rest cam formed only by a base circle, and rotated by a crank output ;
An intake rocker shaft arranged in parallel with the camshaft;
An exhaust rocker shaft disposed in parallel with the camshaft on the opposite side of the camshaft with respect to the intake rocker shaft;
An intake valve that is more driven into the intake cam,
An exhaust valve that is more driven to the exhaust cam,
A boss rotatably supported on the intake rocker shaft, a first valve drive rocker for driving the intake valve, and a rotatable on the intake rocker shaft so as to be displaced following the intake cam An intake rocker arm composed of a first cam follower rocker supported by
A boss rotatably supported by the exhaust rocker shaft, a second valve drive rocker for driving the exhaust valve, and a rotatable to the exhaust rocker shaft so as to be displaced following the exhaust cam An exhaust rocker arm comprising a second cam follower rocker supported by
A transmission mode for transmitting the cam displacement to said first and second valve driving rocker from said first and second cam follower rocker, from the first and second cam follower rocker to said first and second valve driving rocker a sleep mode for blocking transmission of the cam displacement to the input cut possible with the switching unit,
The intake valve and the boss of the first valve drive rocker and the boss of the second valve drive rocker are formed on the boss of the second valve drive rocker, respectively, and when the switching portion is in the pause mode, A pair of slippers that keep the first valve drive rocker and the second valve drive rocker in a predetermined posture so that the exhaust valve maintains a closed state ;
The rest cam is formed with an outer diameter larger than that of the intake cam and the exhaust cam,
The slippers of the first and second valve drive rockers have leg portions that project from the bosses of the first and second valve drive rockers toward the axis of the camshaft, respectively. A taper is formed as it advances in the direction of the cam surface of the pause cam, and a sliding contact is provided at the tip of the cam for the pause cam, and the leg portions of the pair of slippers and The variable valve operating apparatus for an internal combustion engine, wherein the sliding contacts are arranged side by side so as to face each other along a circumferential direction of a cam surface of the pause cam . 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the pair of slippers are such that the leg portion and the sliding contact have the same width dimension .

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