JP2006063871A - Variable valve device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve device in which rotation of a camshaft 3 is transmitted by an offset link 7 and a link mechanism to rocking cams 4, 5, and reliability is ensured by reducing as far as possible the overturning moment acting on the offset link 7 by lift reaction and the like of valves 1, 2, while reducing the driving loss by sliding friction. <P>SOLUTION: While the rocking cam 5 for lifting the valve 2 and the offset link 7 fit to an eccentric cam 6 of the camshaft 3 are coupled by a coupling link 8, and a restriction link 13 for restricting the operation is coupled to the offset link 7. Position of the restriction link 13 is changed by a control arm 12 to change the lift strokes of the valves 1, 2. The coupling link 8 and the restriction link 13 are placed on both sides of the offset link 7 so as to pinch the offset link 7 from both sides in the direction of the axis X of the camshaft 3. Arm length R1 of the overturning moment acting on the offset link 7 by a force F1 applied by the coupling link 8 is constituted shorter than the arm length R2 of fall-restriction moment acting by a force F2 applied by the restriction link 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable valve operating apparatus for an engine configured to be capable of changing a lift amount of a valve, and particularly to a technical field of a structure for ensuring reliability while achieving compactness of the apparatus.

  Conventionally, it is known to change the opening / closing timing and lift amount of a cylinder intake / exhaust valve according to the operating state of an engine. As an example of such a variable valve operating apparatus, an offset link (link arm) is fitted to an eccentric portion (drive cam) provided on a camshaft (drive shaft), and the camshaft lifts an intake valve. A moving cam is also supported in a swingable manner, and an offset link operation accompanying the rotation of the camshaft is transmitted to the swinging cam via a link mechanism (see Patent Document 1). ).

In this variable valve operating apparatus, the link mechanism is constituted by a rocker arm having one end connected to the offset link, and a link rod connecting the other end of the rocker arm to the swing cam. A variable mechanism for changing the position of the rocking fulcrum of the rocker arm is provided, and the distance between the rocking fulcrum of the rocker arm and the axis of the rocking cam is changed according to the operating state of the engine. The valve lift amount is increased by bringing the rocker arm swing fulcrum closer to the swing cam shaft during high engine speed and high load, while the valve lift amount is increased by releasing the swing support point during low engine speed and low load. Can be small.
JP-A-11-107725

  By the way, in the variable valve operating apparatus described in Patent Document 1, a rocker arm is employed as a link mechanism for transmitting the operation of the offset link to the swing cam, and a rocker shaft for supporting the rocker arm is provided. Since this is necessary, it is against the demand for a compact device. The rocker arm has sliding contact portions with the offset link and the link rod at both ends thereof, and also has sliding contact portions with the rocker shaft, so that a driving loss due to sliding friction resistance increases. There is a problem that it is easy.

  On the other hand, when the link mechanism does not employ a rocker arm, and a structure that transmits a driving force to the swing cam by combining a plurality of links, the reaction force of the spring when the valve is lifted, Due to the inertial force, there is a problem that a tilting moment is generated in the offset link. This is because when the offset link and the swing cam are arranged on the same camshaft as in the variable valve system and connected by the link, the lift reaction force of the valve that is dominant in the low engine rotation range is obtained. It will act directly on one side of the offset link via the swing cam and link, and the inertial force that prevails in the high engine speed region will also act biased on one side of the offset link via the link. Because.

  And, for example, when the valve lift amount is relatively large near the lift peak in a driving state where the valve lift amount is relatively large, such as in the middle / high load range, or during high rotation when the inertial force of each part increases. Since the tilting moment of the offset link due to the pressure becomes extremely large, the uneven pressure distribution on the sliding contact surface between the offset link and the eccentric part of the camshaft becomes excessively large, and abnormal uneven wear occurs due to oil film breakage. Or even seizure.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a swing cam in which the rotational movement of the eccentric portion of the camshaft is supported on the same camshaft by an offset link and a link mechanism. In the variable valve system that communicates with the valve, the mechanism of its link mechanism is devised to reduce the drive loss due to sliding friction, while the valve lift reaction force and the inertial force of each part (hereinafter simply referred to as lift This is to ensure reliability by minimizing the falling moment acting on the offset link by the reaction force).

  In order to achieve the above object, in the present invention, the first link for connecting the offset link and the swing cam without using the rocker arm in the link mechanism that regulates the operation of the offset link and transmits the offset link to the swing cam; The second link for restricting the operation of the offset link accompanying the rotation of the camshaft is provided, and the two links are arranged so as to sandwich the offset link from both sides in the axial direction of the camshaft.

  Specifically, according to the first aspect of the present invention, the camshaft having an eccentric portion that rotates in synchronization with the crankshaft of the engine, and a swing that is provided so as to be swingable about the axis of the camshaft and lifts the valve. The movable cam, the offset link rotatably fitted to the eccentric part, the swing cam and the offset link are connected, and the swing cam is operated by the rotation of the eccentric part. A variable valve gear for an engine, comprising: a link mechanism that regulates to swing, and a control member that changes the position of the link mechanism so that the lift amount of the valve by the swing cam changes. To do.

  The link mechanism includes a first link rotatably connected to the swing cam and the offset link by a pin, and a second link rotatably connected to the offset link and the control member by a pin, respectively. The first and second links are disposed on both sides of the offset link in the camshaft axial direction so as to sandwich the offset link.

  With the above configuration, when the eccentric portion rotates along with the rotation of the camshaft, the offset link revolves around the axis of the camshaft, and the connecting portion by the pin of the offset link and the second link is It reciprocates along a predetermined trajectory regulated by the control member via the second link. The operation of the offset link is transmitted to the swing cam via the first link, whereby the swing cam swings and the valve lifts. Then, by changing the position of the second link by the control member and displacing the connecting portion of the second link and the offset link, the movement locus of the offset link can also be changed. The swing mode of the swing cam changes, and the valve lift amount changes.

  As described above, the link mechanism for restricting the operation of the offset link accompanying the rotation of the camshaft eccentric portion so that the swing cam swings is composed of the first and second links. Compared with the case where a rocker arm is employed, the sliding frictional resistance can be reduced, the driving loss can be reduced, and the rocker shaft is unnecessary, which is advantageous for downsizing of the apparatus.

  Further, since the first and second links are disposed on both sides of the offset link, the valve lift reaction force acts only on one side of the offset link from the swing cam via the first link. In addition, even if the inertial force of each part acts from the first link side, it can be supported by the second link from the opposite side so as to suppress the fall of the offset link. As a result, the uneven pressure distribution on the sliding contact surface between the offset link and the eccentric portion of the camshaft can be reduced, and the occurrence of uneven wear and seizure can be suppressed.

  In the above configuration, the distance between the center in the width direction of the sliding contact surface where the offset link is in sliding contact with the eccentric portion of the camshaft and the center in the width direction of the sliding contact surface where the first and second links are in sliding contact with the pins, It is preferable that the first link side is shorter than the second link side (invention of claim 2).

  That is, the arm length of the falling moment acting on the offset link is relatively shortened by the force (lift reaction force, etc.) applied to the offset link via the first link, and on the contrary, the arm is applied from the second link to the offset link. This is because the fall of the offset link can be more effectively suppressed by the second link by relatively increasing the length of the arm of the fall suppression moment due to force.

  In the invention according to claim 1 or 2, preferably, the control member is opposite to the offset link with respect to the second link so as to sandwich the second link together with the offset link from both sides of the camshaft axial direction. And is arranged close to the camshaft so as to partially overlap the movement path of the offset link when viewed along the camshaft axis (invention of claim 3). ).

  By arranging the control member close to the camshaft of the engine in this way, the variable valve operating device can be made compact around the axis of the camshaft, that is, in the vertical and horizontal directions of the engine. Since the control member is disposed on the opposite side of the offset link with respect to the second link, it does not interfere with this.

  Further, in the invention according to any one of claims 1 to 3, when the engine has a plurality of cylinders, the control member is disposed above a rocking cam of another adjacent cylinder. It is preferable that they are arranged so as not to overlap the movement locus of the swing cam when viewed along the camshaft axis (invention of claim 4).

  In this way, since the control member is arranged alongside the swing cam in the vertical direction of the engine, the variable valve system is compact in the longitudinal direction of the engine (in the cylinder row direction where the cylinders of the multi-cylinder engine are lined up). It can be set as a simple structure.

  Alternatively, in the invention of claim 2, the control member is arranged in the middle of the offset link and the second link in the camshaft axial direction, and when viewed along the camshaft axial center, It can also arrange | position so that it may not overlap with the movement locus | trajectory of the pin which connects 2 links (invention of Claim 5).

  By doing so, the offset link and the second link are separated in the camshaft axial direction by the thickness of the control member, so that the arm length of the moment due to the force applied to the offset link from the second link is reduced. Naturally, it becomes long, which is advantageous in obtaining the effect of the invention of claim 2.

  In this case, if the engine has a plurality of cylinders, the second link is disposed above the swing cam of another adjacent cylinder, and the second link is viewed along the camshaft axis. It is preferable to arrange the link so that the movement locus of the link itself does not overlap with the movement locus of the swing cam (invention of claim 6). In this case, since the second link is arranged in the vertical direction along with the swing cam, the variable valve gear can be made compact in the longitudinal direction of the engine, as in the fourth aspect of the invention. .

  As described above, according to the variable valve operating apparatus for an engine according to claim 1 of the present invention, the rotational movement of the eccentric portion of the camshaft supported on the same camshaft by the offset link and the link mechanism. In the variable valve operating apparatus configured to transmit to the cam, the link mechanism includes a first link that connects the offset link and the swing cam, and a second link that regulates the operation of the offset link accompanying the rotation of the camshaft. The first link and the second link are arranged on both sides of the offset link, so that the tilt of the offset link due to the lift reaction force or the like is suppressed, and the sliding contact surface between the offset link and the eccentric portion of the camshaft The occurrence of uneven wear and seizure can be suppressed, and the reliability of the variable valve system can be ensured.

  In particular, as in the second aspect of the invention, the distance between the offset link and the second link is relatively increased, and the tilting link restraining moment of the offset link due to the force from the second link is increased as much as possible, By making the falling moment due to the force from the first link as small as possible, the above-described effect can be sufficiently obtained.

The effect of the present invention is particularly advantageous in the case where the variable valve operating device is made as compact as possible as in the inventions of claims 3 to 6, and this causes severe restrictions on the layout of the control member and each link. It becomes effective.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Basic configuration of variable valve operating device)
FIG. 1 shows an overall configuration in which a variable valve operating apparatus according to an embodiment of the present invention is applied to an intake valve of an engine. In the figure, 3 is a camshaft that rotates in synchronization with the rotation of the crankshaft of the engine. Although not shown, this engine has first, second, third, and fourth from the front side (left side in the figure) in the longitudinal direction of the camshaft 3 toward the rear side (right side). This is an in-line four-cylinder engine with four cylinders arranged in it, adopting a four-valve double overhead cam system with two intake valves 1 and 2 and two exhaust valves (not shown) for each cylinder. is there.

  A pair of swing cams 4, 5 is swingably supported for each cylinder at a portion (camshaft body) of the camshaft 3 other than the eccentric cam 6 described later. The pair of swing cams 4 and 5 are formed integrally with each other so as to correspond to the two intake valves 1 and 2, respectively. That is, both the swing cams 4 and 5 are connected to each other by a cylindrical connecting portion 50 provided therebetween, and around the axis X of the camshaft 3 (the rotation center of the camshaft 3: see FIG. 2 and the like). It swings as a unit. Then, each of the two intake valves 1 and 2 in one cylinder is lifted by the swing cams 4 and 5, respectively. The outer peripheral surface of the connecting portion 50 also serves as a cam journal portion that is in sliding contact with the bearing surface.

  In order to operate the oscillating cams 4 and 5 as described above, the camshaft 3 is integrally provided with four circular eccentric cams 6 (eccentric portions) that are eccentric from the axis X thereof with a space therebetween. ing. An outer ring 7 is rotatably fitted to each eccentric cam 6, and the eccentric protrusion provided so as to protrude from the outer periphery of the outer ring 7 is connected to the eccentric cam 6 via a connecting link 8 (first link). The swing cam 5 is connected. In other words, one end side of the outer ring 7 is rotatably fitted to the eccentric cam 6 of the camshaft 3, and the other end portion (eccentric convex portion) is connected to the swing cam 5 by the connecting link 8 (hereinafter referred to as the outer ring 7). Is called an offset link).

  A control shaft 11 is provided in parallel with the camshaft 3 obliquely above. Four control arms 12 (control members) are coupled and fixed to the control shaft 11, and the leading end portion of each control arm 12 and the other end portion (eccentric convex portion) of the offset link 7 are regulated links 13. It is connected by (second link). The restriction link 13 restricts the displacement of the offset link 7 and reciprocates the other end when the one end side of the offset link 7 revolves around the camshaft 3 as the eccentric cam 6 rotates. Thus, the connecting link 8 connected to the other end of the offset link 7 swings the swing cams 4 and 5.

  In other words, the connecting link 8 and the restriction link 13 connect the swing cam 5 and the offset link 7 and also operate the offset link 7 accompanying the rotation of the eccentric cam 6 with the swing cam 5 (and the swing link 5). A link mechanism that restricts the moving cam 4) to swing is configured. This link mechanism is composed of the two links 8 and 13 and reduces sliding friction resistance as compared with a case where a rocker arm is employed as in a conventionally known one (for example, disclosed in Patent Document 1). As a result, the drive loss can be reduced, and the rocker shaft is unnecessary, which is advantageous for making the apparatus compact.

  A worm gear 14 having teeth formed on only a part of its circumference is coupled to the control shaft 11, and a worm 16 that is rotationally driven by a motor 15 is engaged with the teeth of the worm gear 14. Then, by operating the motor 15 to rotate the control arm 12, the position of the restriction link 13 (the position of the link mechanism) is changed, and thereby the reciprocating motion of the other end of the offset link 7. , That is, the swing trajectory of the connecting link 8 can be changed. As a result, the swing range of the swing cams 4 and 5 changes, and the lift amount and timing of the intake valves 1 and 2 change.

  More specifically, first, as shown in FIG. 2B, a direct acting tappet 21 is provided at the upper end of the stem of the intake valve 2, and the swing cam 5 is in contact with the tappet 21. The intake valve 2 closes the intake port 25 by a valve spring 24 provided between a retainer 22 provided in the tappet 21 and a retainer 23 provided in the cylinder head (a direction opposite to the valve lift direction). ). The intake valve 1 has the same configuration as the intake valve 2.

  One end portion of the connection link 8 is rotatably connected to the swing cam 5 by a pin 31, while one end portion of the regulation link 13 is rotatably connected to a tip portion of the control arm 12 by a pin 32. ing. Thus, the connecting link 8 and the regulating link 13 are disposed on both sides of the offset link 7 and are linked with the offset link 7 interposed therebetween. That is, the other end of each of the connecting link 8 and the regulating link 13 is coaxially and rotatably connected to the other end of the offset link 7 by the connecting pin 33. The pins 31 to 33 all extend parallel to the camshaft 3.

  As shown in the figure, the connecting pin 33 between the offset link 7 and the connecting link 8 is located above the camshaft 3, and the rotation center of the control arm 12 (the axis of the control shaft 11) is located on the side of the connecting pin 33. positioned. The pin 32 at the tip of the control arm 12 is a rotation shaft of the restriction link 13, and the position of the restriction link 13 is changed by changing the position of the pin 32, thereby changing the swing locus of the connecting pin 33. Thus, the lift amount of the intake valves 1 and 2 can be changed.

  That is, the specific operation of each link or pin will be described in detail below. However, when the pin 32 is positioned below the control shaft 11 as shown in FIG. 2, the lift with the largest valve lift at the lift peak is obtained. Enters the control state. Further, when the pin 32 is moved upward by the rotation of the control arm 12 and is positioned above the camshaft 3 as shown in FIG. 3, the valve lift amount at the lift peak becomes the smallest lift control state. Become.

  In the large lift control state shown in FIG. 2, the position of the offset link 7 changes with the rotation of the eccentric cam 6, so that the swing cam 5 is a direct acting tappet 21 as shown in FIG. The lift peak state when the intake valve 2 is greatly lifted via the intake valve (the swing cam 4 lifts the intake valve 1 greatly via the direct acting tappet) and the intake air as shown in FIG. It swings between the lift amount of the valve 2 (intake valve 1) and zero. The same applies to the case of FIG. 3 which is the small lift control state (see FIGS. 3A and 3B).

(Operation of variable valve system)
Hereinafter, the operation of such links and cams will be described in detail with reference to FIGS. In both figures, the control arm 12, the connecting link 8, and the restricting link 13 are simply represented by straight lines, and the rotation trajectory of the center of the eccentric cam 6 (the center of the outer ring of the offset link 7) is indicated as T0. ing. As described above, the relationship between the intake valve 1 and the swing cam 4 is the same as the relationship between the intake valve 2 and the swing cam 5, and the swing cam 4 works in the same manner as the swing cam 5. Now, the relationship between the intake valve 2 and the swing cam 5 will be described.

  First, the profile of the oscillating cam 5 will be described with reference to FIG. 4. On the peripheral surface of the oscillating cam 5, a base circle surface (base circle section) θ1 having a constant radius of curvature within a predetermined angular range and the θ1 Subsequently, a cam surface (lift section) θ2 having a gradually increasing radius of curvature is formed. The figure shows the large lift control state of FIG. 2, and the control arm 12 is in the large lift control position.

  The solid line in FIG. 2 shows the state of FIG. 2B in which the intake valve 2 is in the vicinity of the lift peak. At this time, the pin 31 is pulled up most by the connecting link 8, and the swing cam 5 is The cam nose tip side of the surface θ2 is in contact with the tappet 21. On the other hand, the phantom line shows a state in which the lift amount is zero (FIG. 2A). At this time, the base circle surface θ1 of the swing cam 5 is in contact with the tappet 21, and the valve lift amount is zero (intake valve). 1 and 2 are closed).

  When the camshaft 3 (eccentric cam 6) rotates in the clockwise direction in the figure, one end side (lower end side in the figure) of the offset link 7 moves along the axis X of the camshaft 3 as indicated by the arrow in the figure. Although revolving around, the displacement of the other end portion of the offset link 7 is regulated by a regulation link 13 connected thereto. That is, the restriction link 13 swings between the position of the solid line and the position of the phantom line around the pin 32 positioned below the control shaft 11, and accordingly, the other end side of the offset link 7. The (connecting pin 33) reciprocates around the pin 32 every time the eccentric cam 6 makes one revolution (the movement locus of the connecting pin 33 is shown as T1).

  With the reciprocating arc motion T1 of the connecting pin 33, the other end portion (pin 31) of the connecting link 8 whose one end portion is connected to the offset link 7 by the same connecting pin 33 is reciprocated along a locus shown as T2. The oscillating cam 5 that is circularly moved and is connected to the connecting link 8 by the pin 31 oscillates between the position of the solid line and the position of the phantom line in the figure. That is, when the connecting pin 33 moves upward, the pin 31 is pulled upward by the connecting link 8, and the cam nose of the swing cam 5 pushes down the tappet 21, thereby compressing the valve spring 24 (see FIG. 2). Then, the intake valve 2 is lifted. On the other hand, when the connecting pin 33 moves downward, the tappet 21 is pushed up by the reaction force of the compressed valve spring 24 and the intake valve 2 is closed.

  Next, from the large lift control state, the control arm 12 is pivoted upward about the axis of the control shaft 11 until it becomes substantially horizontal, and as shown in FIG. 3 and FIG. When the pin 32 that is the moving shaft is positioned closer to the front side in the rotational direction of the camshaft 3 than during the large lift control, the small lift control state is established. Also in FIG. 5, as in FIG. 4, the state where the intake valve 2 is in the vicinity of the lift peak is indicated by a solid line, and the state where the lift amount is zero is indicated by a virtual line.

  In this figure, when the camshaft 3 (eccentric cam 6) rotates, the displacement of the connecting pin 33 of the offset link 7 is restricted by the restriction link 13 and is located on the side of the control shaft 11 as in the case of the large lift control. A reciprocating arc motion T3 is performed around the pin 32 (the restriction link 13 reciprocates between the solid line position and the virtual line position in the figure). The pin 31 of the connecting link 8 performs a reciprocating arc motion T4 in accordance with the reciprocating arc motion T3 of the connecting pin 33, and the swing cam 5 connected to the connecting link 8 by the pin 31 is indicated by a solid line in the figure. The intake valve 2 is opened and closed by swinging between the position and the position of the virtual line.

  FIG. 6 shows the lift characteristics of the intake valves 1 and 2 that are changed from the large lift control state to the small lift control state by the change in the position of the restriction link 13 as described above. The illustrated graph L1 shows the lift characteristics at the time of large lift control in which the swing cam 5 swings between the solid line position (near the lift peak at the time of large lift control) and the virtual line position (zero lift) in FIG. On the other hand, the graph L2 shows the lift characteristics at the time of small lift control in which the swing cam 5 swings between the solid line position (near the lift peak at the time of small lift control) and the virtual line position (zero lift) of FIG. ing.

  As shown in the figure, when shifting from the large lift control to the small lift control, the valve lift amount at the lift peak decreases. That is, the lift stroke of the intake valves 1 and 2 is changed by changing the position of the link mechanism (the restriction link 13) by the control arm 12. The lift stroke of the valve can be changed steplessly according to the pivot position by pivoting the control arm 12 between the large lift position and the small lift position shown in FIGS. it can.

  Further, as shown in the figure, the crank angle position at the lift peak is gradually advanced when shifting from the large lift control to the small lift control. This is because the position of the pin 32 that is the rotation shaft of the restriction link 13 is moved forward in the rotational direction of the camshaft 3 by the rotation of the control arm 12 as described above in the transition from the large lift control to the small lift control. This is because the locus of the reciprocating arc motion of the connecting pin 33 is moved from the position T1 in FIG. 4 to the position T3 in FIG.

  Thus, during the large lift control shown in FIG. 4, the center of the eccentric cam 6 when the intake valves 1 and 2 are in the vicinity of the lift peak is located at the point Ta on the rotation locus T0. In the small lift control state shown in FIG. 5, the center position of the eccentric cam 6 near the lift peak moves to a point Tb shown in FIG. That is, when shifting from the large lift control to the small lift control, the lift peak of the intake valve 2 is advanced by the center angle θ3 of the points Ta and Tb on the rotation locus T0 as shown in FIG. .

  As described above, as the valve lift amount in the vicinity of the lift peak is reduced, the peak timing of the valve lift is advanced. Therefore, as shown in FIG. This is advantageous in substantially aligning the valve opening start times. In addition, the positional relationship of each member such as a link and a cam for aligning the valve opening start timing in this way is when the rotation direction of the swing cams 4 and 5 during the valve lift is the same as the rotation direction of the camshaft 3. It is easier to obtain than if it is different.

(Link mechanism layout)
Next, the mutual positional relationship between the link and the cam in the above-described variable valve operating apparatus will be described with reference to FIGS. FIG. 7 is a side view of a portion of the variable valve operating apparatus corresponding mainly to the first cylinder as shown by an arrow VII in FIG. 1, and as shown in FIG. The pair of rocking cams 4 and 5 for lifting the two intake valves 1 and 2 are connected by a connecting portion 50 to be integrated, and one of them (in the example shown, the rear side of the engine close to the second cylinder). A connecting link 8 that connects the swing cam 5 to the offset link 7 is disposed adjacent to the swing cam 5.

  That is, the offset link 7 that operates in synchronization with the rotation of the camshaft 3 and the swing cams 4 and 5 that lift the intake valves 1 and 2 in conjunction with this are arranged on the same camshaft 3, By connecting with the connecting link 8, the variable valve operating device can be made compact. In this case, the two swing cams 4, 5 for each cylinder are connected to the offset link 7 by one connecting link 8. As a result, the number of parts can be reduced and the configuration can be simplified, which is also advantageous for making the variable valve operating apparatus compact.

  Further, on the side opposite to the connecting link 8 across the offset link 7, a regulation link 13 is disposed adjacent to the offset link 7, and further, with the offset link 7 across the regulation link 13. On the opposite side, a control arm 12 is disposed adjacent to the restriction link 13. In other words, the offset link 7 is disposed in a limited space between the swing cam 5 of the first cylinder and the swing cam 4 of the second cylinder adjacent thereto, and the offset link 7 is arranged in the engine longitudinal direction (camshaft). The connecting link 8 and the regulating link 13 are arranged so as to be sandwiched from both sides in the direction of the axis X).

  The restriction link 13 is disposed above the boss portion of the eccentric cam 6 so as not to interfere with the boss portion, and the control arm 12 adjacent to the restriction link 13 is located above the swing cam 4 of the second cylinder. In addition, they are arranged so as not to interfere with this. That is, when viewed along the camshaft axis X as shown in FIG. 8, the control arm 12 is in a large lift control position where the tip end portion is positioned at the lowest position. Even when the largest swinging range is swung on the camshaft 3, it is arranged so as not to overlap the movement locus.

  As described above, the control arm 12 of the first cylinder is arranged side by side above the swing cam 4 of the adjacent second cylinder, that is, the control arm 12 and the swing cam 4 are overlapped in the longitudinal direction of the engine. Therefore, the variable valve gear can be made compact in the longitudinal direction of the engine.

  Further, as is apparent in the figure, when viewed along the camshaft axis X, the control arm 12 overlaps the upper portion of the offset cam 7 in the vicinity of the lift peak in the large lift control state. That is, the control arm 12 is disposed close to the camshaft 3 so as to partially overlap the movement locus of the offset link 7 when viewed along the camshaft axis X.

  By making the control arm 12 close to the camshaft 3 in this way, the variable valve operating apparatus can be made compact in the vertical and horizontal directions around the axis of the camshaft 3. The rotational center of the arm 12 (axial center of the control shaft 11) is arranged at a low level so that the variable valve operating device does not become bulky.

  By the way, when the offset link 7 and the swing cams 4 and 5 are arranged on the same camshaft 3 and are connected by the connecting link 8 as described above, the valve spring 24 for lifting the intake valves 1 and 2 is used. The compression reaction force acts only on one side (right side in the figure) of the offset link 7 as shown in an enlarged view in FIG. This force is shown as F1). Although not shown, the inertial force of each component also acts biased to one side of the offset link 7 via the connecting link 8.

  As a result, for example, when the reaction force from the valve spring 24 becomes maximum in the vicinity of the lift peak in the large lift control state where the engine is in the low rotation range and the lift stroke of the valve is relatively large, FIG. Since a very large force F1 acts on one side as shown in FIG. 2, a large tilting moment acts on the offset link 7 in the clockwise direction in the drawing so as to pull the offset link 7 toward the connecting link 8 side. Further, when the engine is in the high rotation range, the influence of the inertial force becomes large, and a large falling moment acts in a direction different from the moment due to the force F1.

  The distribution of the surface pressure on the sliding contact surface 6a between the offset link 7 and the eccentric cam 6 of the camshaft 3 is excessively biased due to the action of the large tilting moment (see FIG. 9B), and the oil film There is a possibility that abnormal wear may be caused by cutting and further seizure.

  In contrast, in this embodiment, as described above, first, the restriction link 13 for restricting the operation of the offset link 7 is arranged on the side opposite to the connection link 8, and the two links 8 and 13 are used for offsetting. The link 7 is sandwiched from both sides in the camshaft axis X direction. Thereby, the fall of the offset link 7 due to the force F1 from the connecting link 8 can be suppressed by the restriction link 13 from the opposite side. Furthermore, the length of the arm of the moment is relatively increased so that the fall-suppressing moment acting on the offset link 7 by the force F2 from the restriction link 13 is as large as possible.

  That is, as shown in FIG. 7B, the other end portion (upper end portion in the figure) of the offset link 7 in which the end portions of the connection link 8 and the regulation link 13 are connected coaxially by the connection pin 33 is provided. The boss portion 7a protruding toward the restriction link 13 is formed, and the distance between the two (the offset link 7 and the restriction link 13) is increased accordingly. The length of the arm of the fall suppression moment acting on the offset link 7 by the force F2 is increased.

  In other words, as shown in the figure, the center line C0 in the width direction (camshaft axis X direction) of the sliding contact surface 6a on the outer periphery of the eccentric cam 6 that is in sliding contact with the offset link 7, the connecting link 8 and the regulating link 13 are respectively The distance (camshaft axis center) between the center lines C1 and C2 in the width direction (axial direction of the coupling pin 33 parallel to the camshaft axis X) in the sliding contact surfaces 33a and 33b on the outer periphery of the linking pin 33 in sliding contact The distances R1 and R2 in the X direction are such that the distance R1 on the connection link 8 side (right side in the figure) is shorter than the distance R2 on the restriction link 13 side (left side in the figure).

  Thus, if the distance between the offset link 7 and the connecting link 8 is relatively shorter than the distance between the restriction link 13 and they are made the same (R1 = R2), the intake valve 1 , 2 can reduce the fall moment of the offset link 7 due to the force F1 acting from the connecting link 8 side, and increase the fall restraining moment due to the force F2 acting from the restriction link 13 side at that time. it can. Thereby, the fall of the offset link 7 can be suppressed, the deviation of the pressure distribution on the sliding contact surface 6a with the eccentric cam 6 can be reduced, and the occurrence of uneven wear and seizure can be more reliably suppressed.

  FIG. 9 shows the result of the pressure distribution on the sliding contact surface 6a between the offset link 7 and the eccentric cam 6 obtained by simulation under an operating condition in which the engine is in the low rotation range and the lift amount is relatively large. (A) is an Example (R1 <R2) of the present invention, and (b) is a comparative example (R1 = R2). Comparing these figures (a) and (b), it can be seen that according to the present invention, the bias of the pressure distribution is greatly reduced as compared with the comparative example.

  Therefore, according to the variable valve operating apparatus according to this embodiment, by changing the position of the restriction link 13 by the rotation of the control arm 12, the intake valve 1, 2 lift stroke by the swing cams 4, 5 is greatly changed. Therefore, it becomes possible to obtain the optimum intake amount according to the engine operating state only by controlling the lift stroke, and the pumping loss can be reduced by eliminating the throttle valve in the intake passage. It is possible to improve the intake charge efficiency at high load.

  Further, the two oscillating cams 4 and 5 for each cylinder are integrated, and an eccentric cam 6 and an offset link 7 for oscillating the cams are arranged on the same camshaft 3 in a narrow space between the cylinders. In addition to being connected by one connecting link 8, a control link 13 and a control arm 12 for controlling the operation of the offset link 7 are arranged close to the upper side of the camshaft 3, and the control arm 12 is The variable valve system is made compact by devising the arrangement of the links 7, 8, 13 and the cams 4, 5 such as arranging them side by side above the swing cam 4 of another adjacent cylinder. can do.

  Further, the connecting link 8 and the regulating link 13 for connecting the offset link 7 to the swing cam 5 and the control arm 12 are disposed on both sides of the offset link 7 so as to sandwich the offset link 7. Even if a lift reaction force or the like acts only on one side of the offset link 7 via this, a tilting suppression moment acts on the offset link 7 by the restriction link 13 from the opposite side against the tilting moment acting on the offset link 7. Can be made.

  Moreover, in the variable valve system that is compactly configured as described above and has severe restrictions on the layout of links and cams, as shown in FIG. 7B, the distance between the offset link 7 and the restriction link 13 is relatively set. By increasing the length of the arm of the tilting suppression moment and increasing the length of the arm, the tilting of the offset link 7 can be effectively suppressed, whereby the sliding contact surface 6a between the offset link 7 and the eccentric cam 6 can be suppressed. The occurrence of uneven wear and seizure can be suppressed, and the reliability of the variable valve system can be ensured.

  In the above-described embodiment, in order to further increase the arm length of the tilting suppression moment of the offset link 7 due to the force F2 acting from the restriction link 13, as shown in FIG. It is also conceivable that the position of the link 13 is changed, and the control arm 12 is arranged in the middle of the offset link 7 and the restriction link 13 in the camshaft axis X direction.

  In this case, the control arm 12 needs to be arranged so as not to overlap the movement locus of the connecting pin 33 that connects the offset link 7 and the restriction link when viewed along the camshaft axis X, and the restriction link 13. Are arranged above the rocking cams 4 of adjacent cylinders so as not to interfere with each other (when viewed along the camshaft axis X, the movement locus of the restriction link 13 itself is the movement locus of the rocking cam 4). It is preferable to arrange them so that they do not overlap.

  And if comprised in that way, since the offset link 7 and the control link 13 will be separated in the camshaft axis X direction by the thickness of the control arm 12 compared to the above-described embodiment, The length of the arm of the fall suppression moment acting on the offset link 7 due to the force F2 applied from the restriction link 13 is increased, which is advantageous in obtaining the effects of the invention described above. However, in that case, as shown in the figure, the control arm 12 may have to be moved upward in order to avoid interference with the connecting pin 33, which increases the position of the control shaft 11. From the viewpoint of making the variable valve operating apparatus compact, it is preferable to configure as in the above embodiment.

  The control member of the present invention is not limited to the control arm 12 as in the above embodiment, but the position of the restriction link 13 is changed so that the lift amount of the intake valves 1 and 2 by the swing cams 4 and 5 changes. Anything is possible.

  Furthermore, the present invention can be applied not only to the intake valve but also to the exhaust valve.

  The present invention is a variable valve operating device that changes the opening / closing timing and valve lift amount of an intake / exhaust valve of an engine, and can ensure reliability while achieving compactness. It is particularly useful as a valve operating device for an automobile engine.

1 is a perspective view showing an embodiment in which a variable valve system of the present invention is applied to an intake side of an in-line four-cylinder engine. It is sectional drawing which shows the state at the time of the large lift control of a variable valve apparatus, (a) shows a lift amount zero state, (b) shows a lift peak state. It is sectional drawing which shows the state at the time of the small lift control of a variable valve apparatus, (a) shows a lift amount zero state, (b) shows a lift peak state. It is explanatory drawing of the action | operation at the time of the large lift control of a variable valve apparatus. It is explanatory drawing of the action | operation at the time of the small lift control of a variable valve apparatus. It is a graph which shows the valve lift characteristic of a variable valve apparatus. FIG. 7 is a view taken along the line VII in FIG. FIG. 8 is a view taken along the line VIII in FIG. 7 showing the layout of the link mechanism as viewed from the front of the engine. It is a figure which shows the simulation result of the surface pressure distribution in the sliding contact surface of an eccentric cam, (a) shows Example R1 <R2, (b) shows comparative example R1 = R2. FIG. 8 is a view corresponding to FIG. 7 according to another embodiment in which the positions of the control arm 12 and the restriction link 13 are exchanged.

Explanation of symbols

1, 2 Intake valve 3 Camshaft 4, 5 Swing cam 6 Eccentric cam (Eccentric part)
7 Offset link 8 Link (first link)
11 Control shaft 12 Control arm (control member)
13 Regulation link (second link)
31-33 Pin R1 The length of the arm of the falling moment (between the center in the width direction of the sliding contact surface where the offset link is in sliding contact with the eccentric portion of the camshaft and the width direction center of the sliding contact surface where the first link is in sliding contact with the pin distance)
R2 Arm length of tilting suppression moment (distance between the center in the width direction of the sliding contact surface where the offset link is in sliding contact with the eccentric portion of the camshaft and the center in the width direction of the sliding contact surface where the second link is in sliding contact with the pin)

Claims (6)

A camshaft having an eccentric portion that rotates in synchronization with the crankshaft of the engine;
A swing cam provided so as to be swingable about the axis of the camshaft and lifting the valve;
An offset link rotatably fitted to the eccentric part;
A link mechanism that couples the swing cam and the offset link, and restricts the operation of the offset link accompanying the rotation of the eccentric portion so that the swing cam swings;
A variable valve operating apparatus for an engine, comprising: a control member that changes a position of the link mechanism so that a lift amount of the valve by the swing cam changes;
The link mechanism is
A first link rotatably connected to each of the swing cam and the offset link by a pin;
A second link rotatably connected to the offset link and the control member by a pin,
A variable valve operating apparatus for an engine, wherein the first link and the second link are disposed on both sides of the offset link in the cam shaft axial direction so as to sandwich the offset link. The variable valve operating apparatus for an engine according to claim 1,
The distance between the center in the width direction of the slidable contact surface where the offset link slidably contacts the eccentric portion of the camshaft and the width direction center of the slidable contact surface where each of the first and second links slidably contact the pin is A variable valve operating system for an engine characterized by being shorter than the second link side. The variable valve operating apparatus for an engine according to claim 1 or 2,
The control member is arranged on the opposite side of the offset link with respect to the second link so as to sandwich the second link together with the offset link from both sides in the camshaft axial direction, and along the camshaft axis. The variable valve operating apparatus for an engine is characterized in that it is arranged close to the camshaft so as to partially overlap a movement locus of the offset link. The variable valve operating apparatus for an engine according to any one of claims 1 to 3,
The engine has a plurality of cylinders,
The control member is disposed above the rocking cam of another adjacent cylinder, and is disposed so as not to overlap the movement locus of the rocking cam when viewed along the camshaft axis. A variable valve operating device for an engine. The variable valve operating apparatus for an engine according to claim 2,
The control member is disposed in the middle of the offset link and the second link in the camshaft axial direction, and a pin for connecting the offset link and the second link when viewed along the camshaft axis. A variable valve operating apparatus for an engine, which is arranged so as not to overlap with a movement locus. The variable valve operating apparatus for an engine according to claim 5,
The engine has a plurality of cylinders,
The second link is disposed above the swing cam of another adjacent cylinder, and the movement track of the second link overlaps with the movement track of the swing cam as viewed along the camshaft axis. A variable valve operating system for an engine, characterized by being arranged so as not to become.