JP6003695B2 - Engine valve gear - Google Patents

Description

  The present invention relates to a valve operating apparatus for an engine, and more particularly, to a valve operating apparatus for an engine with improved mountability on the engine.

  2. Description of the Related Art Conventionally, there has been known an engine valve operating device configured to be able to switch valve operating characteristics such as a lift amount and opening / closing timing of an intake / exhaust valve according to an operating state of the engine. This valve operating apparatus includes a camshaft that rotates in conjunction with a crankshaft of an engine, and a cam element that is externally fitted to the camshaft so as to be movable in the axial direction and rotates integrally with the camshaft. The cam element includes a plurality of cams having different cam profiles arranged along the axial direction of the crankshaft, and is provided for each intake valve or exhaust valve. When the cam element moves in the axial direction and the cam that presses the cam follower is switched, the valve operating characteristics of the intake and exhaust valves are switched according to the cam profile.

  The valve gear disclosed in Patent Literature 1 is provided on one end side in the axial direction of the cam element as means for moving the cam element in the axial direction, and the axial direction in which the protruding amount in the axial direction varies along the circumferential direction. An end face cam member including a cam and a position where the end face cam member is in contact with the axial cam and a non-contact position where the end face cam member is not in contact are provided so as to be movable. And an operation pin for moving the cam element in the axial direction by applying a pressing force of.

  Here, the valve gear disclosed in Patent Document 1 is mounted on a multi-valve engine provided with two intake valves or exhaust valves per cylinder. Therefore, two cam elements corresponding to two intake valves or exhaust valves are provided side by side in the axial direction at a predetermined interval. The two cam elements are connected to each other by a cylindrical extension extending in the axial direction, and the extension is supported by a bearing portion standing on the cylinder head so as to be movable in the axial direction and rotatable in the circumferential direction. Yes. That is, the bearing portion is arranged between the two cam elements.

US Patent Publication 2011/0226205

  Incidentally, the valve operating device disclosed in Patent Document 1 is provided with a detent mechanism for positioning a plurality of cams connected to the cam element with respect to the cam follower. The detent mechanism has a ball member provided on the cam shaft in a state of being biased so as to protrude radially outward from the outer peripheral surface of the cam shaft, and a position corresponding to a plurality of cams on the inner peripheral surface of the cam element. A plurality of concave grooves formed along the circumferential direction of the cam element. When the cam element is moved in the axial direction and the cam is switched, the ball member comes out of the groove corresponding to the switching source cam and is fitted into the groove corresponding to the switching destination cam. Axial movement is restricted and the cam is positioned relative to the cam follower.

  However, when the momentum of the movement of the cam element is strong, there is a possibility that the cam element excessively collides with the bearing portion. Then, noise is generated and the cam element and the bearing portion may be damaged.

  In order to deal with this problem, it is proposed to leave a relatively large clearance between the cam element and the bearing part. However, since this increases the axial distance between the two cam elements, the valve operating device can only be mounted on a large engine having a relatively long axial distance (valve pitch) between adjacent valves, There is a problem that the engine cannot be downsized.

  Further, in order to cope with the above problem, it is proposed to use a cylindrical groove cam member in which a concave groove is formed on the outer periphery of the cylinder instead of the end face cam member as means for moving the cam element in the axial direction. That is, the operating pin is engaged with the concave groove of the cylindrical groove cam member to positively move the cam element along the concave groove. However, if so, a wall is formed on the side of the cylinder next to the groove, and the axial distance from the cam element of the adjacent cylinder must be increased by the thickness of the wall. Therefore, there is a problem that the valve operating device can be mounted only on a large engine having a relatively long axial distance (cylinder pitch) between cylinders adjacent to each other, and the engine cannot be downsized.

  Such a problem is not limited to the collision between the cam element and the bearing portion, and is applied when an abutting member such as a rib or a pipe is disposed on the side where the cam element approaches when the cam is switched. This is a problem that may occur even when the cam element may collide with the contact member.

  Accordingly, the present invention reduces the noise caused by the collision between the cam element and the abutting member and the breakage of the cam element and the abutting member, while shortening the axial distance between the adjacent cam elements, The purpose of the present invention is to provide a valve operating system for an engine with improved mountability.

In order to solve the above-mentioned problems, the present invention is an engine valve operating device capable of switching the valve operating characteristics of an intake / exhaust valve according to the operating state of the engine, and rotates in conjunction with the crankshaft of the engine. And a plurality of cams that are externally fitted to the cam shaft so as to be movable in the axial direction, rotate integrally with the cam shaft, and have cam profiles that are continuously provided along the axial direction of the crankshaft. Including a cam element, a cam switching means for switching the cam by moving the cam element in the axial direction, and a contact member disposed on the side where the cam element approaches when the cam is switched by the cam switching means, A collision mitigation means for mitigating a collision between the cam element and the contact member when the cam is switched by the cam switching means is provided. BenSo location.

  According to the present invention, in the valve operating device of the engine capable of switching the valve operating characteristics of the intake and exhaust valves according to the operating state of the engine, even when the cam element collides with the contact member at the time of switching the cam, the collision Since the collision is mitigated by the mitigation means, noise caused by the collision and damage to the cam element and the contact member are suppressed.

  Moreover, in order to avoid a collision between the cam element and the contact member, a relatively large clearance is not left between the cam element and the contact member, or a cylindrical groove cam member is not used in place of the end face cam member. Therefore, the valve gear can be mounted on a small engine having a relatively short valve pitch or cylinder pitch.

  As described above, according to the present invention, in the valve operating device for an engine capable of switching the valve operating characteristics of the intake / exhaust valve according to the operating state of the engine, noise caused by the collision between the cam element and the abutting member and the cam element In addition, the axial distance between the cam elements adjacent to each other is shortened while the breakage of the abutting member is suppressed, and the mountability to the engine is improved.

In the present invention, preferably, the cam element is provided with an extension portion extending in the axial direction, and the extension portion is provided with a bearing portion for bearing the cam element so as to be movable in the axial direction and rotatable in the circumferential direction. abutting member Ru said bearing portion der.

  According to this configuration, in the valve operating device of the engine that can switch the valve operating characteristics of the intake / exhaust valve according to the operating state of the engine, even when the cam element collides with the bearing portion when switching the cam, the collision mitigation Since the collision is mitigated by the means, noise caused by the collision and damage to the cam element and the bearing portion are suppressed.

  Moreover, in order to avoid a collision between the cam element and the bearing portion, a relatively large clearance is not left between the cam element and the bearing portion, or a cylindrical groove cam member is not used instead of the end face cam member. The valve gear can be mounted on a small engine having a relatively short valve pitch or cylinder pitch.

  As described above, according to this configuration, in the valve operating device of the engine capable of switching the valve operating characteristics of the intake / exhaust valve according to the operating state of the engine, noise caused by the collision between the cam element and the bearing portion, the cam element, While the breakage of the bearing portion is suppressed, the axial distance between the cam elements adjacent to each other is shortened, and the mountability to the engine is improved.

In the present invention, it is preferable that two cam elements are provided in the axial direction with a predetermined interval per cylinder, and the extension portion connects the two cam elements to each other. the bearing portion is disposed between the two cam elements, said shock absorbing means Ru der which mitigate collisions with each of the bearing portions of the two cam elements.

  According to this configuration, for example, a valve operating apparatus for a multi-valve engine provided with two intake valves or exhaust valves per cylinder is provided. The two cam elements corresponding to the two intake valves or the exhaust valve are connected to each other by an extension portion, and in this extension portion, the two cam elements can be moved in the axial direction by a bearing portion disposed between the two cam elements and can be Bearings are rotatable in the direction. For each cam element, the collision with the bearing portion when the cam is switched is alleviated. Therefore, the two cams are switched so that one of the two cam elements moves close to the bearing so that one cam element moves close to the bearing, and two cams so that the other cam moves close to the bearing. The noise caused by the collision between the cam element and the bearing portion and the breakage of the cam element and the bearing portion are suppressed both at the time of switching the cam in which the element is moved simultaneously.

In the present invention, preferably, the collision mitigation means includes a circular concave groove centering on an axis of a cam shaft formed on one of opposing surfaces of the cam element and the bearing portion, the cam element, and the cam element. wherein formed on the other surface facing the bearing portion through the oil circular groove that is configured to include a ridge that fits.

  According to this configuration, a specific example of the collision mitigation unit is shown. That is, oil, such as lubricating oil, accumulates in a circular groove formed on one of the opposing surfaces of the cam element and the bearing portion, and in the event of a collision, a ridge formed on the other of the opposing surfaces of the cam element and the bearing portion. However, the oil accumulated in the circular concave groove serves as a damper, and the impact of the collision is effectively reduced.

  The present invention relates to an engine valve device capable of switching the valve operating characteristics of an intake / exhaust valve in accordance with the operating state of the engine, and is caused by a collision between a cam element and a contact member such as a rib, a pipe, or a bearing portion. While suppressing noise and breakage of the cam element and the abutting member, the axial distance between adjacent cam elements is shortened and the mountability to the engine is improved. Contributes to the development and improvement of valve device technology.

It is a front view of the valve operating apparatus of the engine which concerns on embodiment of this invention. FIG. 2 is a side view of an exhaust camshaft and an operation pin driving device of the valve gear as viewed from an arrow A in FIG. 1. It is an expanded sectional view of the cam shaft and cam element of the exhaust camshaft. It is the elements on larger scale which show the ditch | groove and the inclined surface which were formed in the internal peripheral surface of the said cam element. It is a schematic diagram of the said cam element, an end surface cam member, and a bearing part. It is a side view of the said cam element and an end surface cam member. It is a perspective view of the said cam element and an end surface cam member. It is explanatory drawing of a ditch | groove pitch and a 2nd pressing force generation required distance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Overall Configuration In the present embodiment, the present invention is applied to the valve gear 1 for an engine shown in FIG. A valve operating apparatus 1 shown in FIG. 1 is a valve operating apparatus for an exhaust valve 2 and includes a swing arm type rocker arm 3. The rocker arm 3 presses the exhaust valve 2 and the fulcrum 3a supported by the lash adjuster 4 that automatically adjusts the valve clearance, the force point 3b provided with the cam follower 7 pressed by the cam 6 of the exhaust camshaft 5, and the exhaust valve 2. Point 3c. The valve gear 1 is disposed in an engine cylinder head (not shown).

  As shown in FIG. 2, the engine E according to this embodiment is an in-line four-cylinder engine in which four cylinders C (first cylinder C1 to fourth cylinder C4) are arranged in series in a direction in which a crankshaft (not shown) extends. It is. The engine E is a multi-valve engine provided with two intake valves (not shown) and two exhaust valves 2 per cylinder C.

  The valve gear 1 is configured to be able to switch the valve characteristics such as the lift amount and opening / closing timing of the exhaust valve 2 by switching the cam 6 of the exhaust camshaft 5 according to the operating state of the engine E. Yes. Although the present invention can be applied to a valve gear for an intake valve, in the present embodiment, a case where the present invention is applied to a valve gear for an exhaust valve 2 will be described as an example.

  The exhaust camshaft 5 is connected to a camshaft 8 that rotates in conjunction with the crankshaft, and the camshaft 8 is connected to the camshaft 8 via splines 9a and 9b (see FIGS. 4 and 5). And a cam element 10 that is externally fitted so as to be movable in the left-right direction) and rotates integrally with the cam shaft 8. The cam element 10 includes an A cam 6A and a B cam 6B having mutually different cam profiles provided along the axial direction, and is provided for each exhaust valve 2. When the cam element 10 moves in the axial direction and the cam 6 that presses the cam follower 7 of the rocker arm 3 is switched, the valve operating characteristic of the exhaust valve 2 is switched according to the cam profile.

  As described above, in the present embodiment, since the two exhaust valves 2 are provided per cylinder C, the cam element 10 is also provided with two cam elements 10 per cylinder C. The two cam elements 10 corresponding to the two exhaust valves 2 are provided side by side in the axial direction at a predetermined interval, and are connected to each other by a cylindrical extension portion 11 extending in the axial direction. In the present embodiment, the two cam elements 10 connected to each other are referred to as a cam unit 12. That is, one cam unit 12 is provided for each cylinder C.

  As shown in FIG. 3, the cam unit 12 is supported by the bearing portion 30 erected on the cylinder head in the extension portion 11 so as to be movable in the axial direction and rotatable in the circumferential direction. That is, the bearing portion 30 is disposed between the two cam elements 10. The bearing portion 30 includes a support wall 31 integrally formed with the cylinder head, and a cam cap 32 fastened and fixed to the support wall 31.

  As a means for moving the cam element 10 or the cam unit 12 in the axial direction, as shown in FIGS. 4 to 7, one end side of the cam element 10 in the axial direction (the cam unit 12 in the axial direction of the cam unit 12). The end face cam member 13 is provided on the side. The end face cam member 13 includes an axial cam 13a in which the amount of axial protrusion varies along the circumferential direction. Further, as shown in FIGS. 2 and 5, an operation pin 21 is provided as a forcible moving member capable of moving forward and backward with respect to the end face cam member 13. The operation pin 21 is a plunger of an electromagnetic valve (solenoid valve) 20 as an operation pin driving device. Therefore, the operation pin 21 is provided so as to be movable between a contact position that contacts the axial cam 13a of the end cam member 13 and a non-contact position that does not contact when the electromagnetic valve 20 is turned ON or OFF. The electromagnetic valve 20 is assembled to the cylinder head and fixed in position.

  For example, when the solenoid valve 20 is turned ON, the operation pin 21 advances with respect to the end face cam member 13 and comes into contact with the axial cam 13a (contact position). At this time, the operation pin 21 comes into contact with the base portion where the axial protrusion amount of the axial cam 13a is zero. Thereafter, as the cam element 10 rotates, the contact point between the axial cam 13a and the operation pin 21 moves to the apex where the axial protrusion amount of the axial cam 13a is large. Thereby, since the position of the operation pin 21 is fixed, the cam element 10 is given an axial pressing force (that is, the first pressing force) from the operation pin 21 and is axially moved away from the operation pin 21. Moved. The axial protrusion amount K (see FIG. 5) of the axial cam 13a corresponds to the operation amount of the axial cam 13a. On the other hand, when the solenoid valve 20 is turned off, the operation pin 21 is retracted from the end face cam member 13 and is not in contact with the axial cam 13a (non-contact position).

  As shown in FIG. 3, the valve operating apparatus 1 according to this embodiment includes a detent mechanism 40 for positioning the A cam 6 </ b> A and the B cam 6 </ b> B connected to the cam element 10 with respect to the cam follower 7 of the rocker arm 3. Is provided. The detent mechanism 40 includes a ball member 43 as a fitting member provided on the cam shaft 8 in a state of being biased so as to protrude radially outward from the outer peripheral surface of the cam shaft 8, An A groove 51 and a B groove 52 formed along the circumferential direction of the cam element 10 are provided at positions corresponding to the A cam 6A and the B cam 6B on the circumferential surface.

  The ball member 43 is urged radially outward by a spring 42 accommodated in a deep hole 41 formed in the camshaft 8 in the radial direction. As shown in FIG. 4, the concave grooves 51 and 52 are partitioned in the axial direction via a convex portion 55 projecting radially inward. The concave grooves 51 and 52 are formed in such a size that the ball member 43 can be fitted when the cam 6 is switched by the axial movement of the cam element 10, and the width, depth, cross-sectional shape, etc. Are formed the same.

  In the present embodiment, the groove (A groove 51 or B groove 52) into which the ball member 43 is fitted before the cam element 10 is moved in the axial direction by the operation pin 21 is referred to as a first groove. The concave groove (B concave groove 52 or A concave groove 51) into which the ball member 43 is fitted after the cam element 10 is moved in the axial direction is referred to as a second concave groove.

  When the cam 6 is switched by moving the cam element 10 or the cam unit 12 in the axial direction, the ball member 43 of the detent mechanism 40 has a first groove (A) corresponding to the switching source cam (A cam 6A or B cam 6B). By slipping out of the groove 51 or B groove 52) and fitting into the second groove (B groove 52 or A groove 51) corresponding to the switching destination cam (B cam 6B or A cam 6A) The movement of the cam element 10 or the cam unit 12 in the axial direction is restricted, and the cam 6 is positioned with respect to the cam follower 7.

  For example, FIGS. 3 and 5 show a state in which the B cam 6B presses the cam follower 7 (note that FIGS. 3 and 5 show a “third cam unit” to be described later). At this time, the cam unit 12 moves to the left in FIGS. 3 and 5, and the right cam element 10 is close to the bearing portion 30. The ball member 43 of the detent mechanism 40 is fitted into the B concave groove 52 corresponding to the B cam 6B by the outward urging force of the spring 42 (that is, the B concave groove 52 is the first concave groove). From this state, when the left solenoid valve 20 in FIG. 5 is turned ON and the cam unit 12 moves to the right in FIGS. 3 and 5, the cam 6 that presses the cam follower 7 is switched from the B cam 6B to the A cam 6A. . At this time, the left cam element 10 in FIG. 3 and FIG. 5 is close to the bearing portion 30, and the ball member 43 of the detent mechanism 40 comes out of the B concave groove 52 and is relative to the A concave groove 51 corresponding to the A cam 6A. It moves and fits into the A groove 51 by the outward urging force of the spring 42 (that is, the A groove 51 is the second groove). The reverse operation is the same as above.

  As shown in FIG. 4, two inclined surfaces 53 and 54 are formed in the circumferential direction corresponding to the two concave grooves 51 and 52 on the inner peripheral surface of the cam element 10. The two inclined surfaces 53 and 54 are formed between the two concave grooves 51 and 52. The A inclined surface 53 is formed continuously with the A groove 51 and the B inclined surface 54 is formed continuously with the B groove 52.

  That is, as described above with reference to FIGS. 3 and 5, when the cam 6 is switched from the B cam 6B to the A cam 6A, the B groove 52 is the first groove, and the A groove 51 is the second groove. In the case of the concave groove, the A inclined surface 53 is formed continuously with the A concave groove 51 which is the second concave groove. Conversely, when the cam 6 is switched from the A cam 6A to the B cam 6B, if the A groove 51 is the first groove and the B groove 52 is the second groove, it is the second groove. A B inclined surface 54 is formed continuously to the B concave groove 52.

  The two inclined surfaces 53 and 54 are formed so that their widths and inclination angles (angles between the inclined surfaces 53 and 54 and the axis of the cam element 10), cross-sectional shapes, and the like are mirror images of each other. Therefore, the convex part 55 which is a ridge line where the two inclined surfaces 53 and 54 intersect is located in the middle between the two concave grooves 51 and 52 in the axial direction.

  When the cam 6 is switched, the ball member 43 of the detent mechanism 40 that has slipped out of the first concave groove 51 or 52 is biased outwardly by the spring 42 during the period until it is fitted into the second concave groove 52 or 51. Accordingly, the inclined surfaces 53 and 54 continuously receive the outward biasing force from the ball member 43. Thereby, the first half of the period (generally before the ball member 43 gets over the convex portion 55) is camped by the contact between the operation pin 21 and the axial cam 13a due to the contact between the ball member 43 and the inclined surface 53 or 54. A pressing force having an axial component opposite to the first axial pressing force applied to the element 10 (that is, an axial component toward the side close to the operation pin 21) is applied to the cam element 10. On the other hand, the latter half of the period (generally after the ball member 43 has climbed over the convex portion 55), the contact between the ball member 43 and the inclined surface 54 or 53 causes the same axial component (that is, operation) as the first pressing force. A pressing force (that is, a second pressing force) having an axial component toward the side away from the pin 21 is applied to the cam element 10.

  This will be described in more detail with reference to FIG. FIG. 8 is an enlarged view of FIG. 4 schematically. In FIG. 8, reference numeral 43 i denotes a ball member fitted in the A groove 51, reference numeral 43 ii denotes a ball member that has just slipped out of the A groove 51 and got over the protrusion 55, and reference numeral 43 iii denotes a protrusion. 55 shows the ball member fitted in the B concave groove 52 after getting over 55, and the symbols Xi, Xii, and Xiii indicate the centers of the respective ball members 43i, 43ii, and 43iii.

  In FIG. 8, when the ball member (43 i) fitted in the A concave groove 51 comes out of the A concave groove 51, gets over the convex portion 55 (43 ii), and fits in the B concave groove 52 (43 iii), That is, consider a case where switching from the A cam 6A to the B cam 6B is performed. In FIG. 8, for the sake of convenience, the ball member 43 is depicted as moving from the left to the right with respect to the cam element 10, but actually the cam element 10 moves with respect to the ball member 43 from the right to the left.

  In this case, the moving distance of the cam element 10 in the axial direction is equal to the axial distance (that is, the groove pitch) L between the first groove 51 as the switching source and the second groove 52 as the switching destination. Here, as shown in the figure, the concave groove pitch L is the center Xi of the ball member 43i fitted in the first concave groove 51 and the ball fitted in the second concave groove 52. It is defined as the axial distance between the member 43iii and the center Xiii.

  In FIG. 8, the position of the ball member 43ii is the second pressing force generation start position. That is, the second pressing force generation start position is determined by the contact between the B inclined surface 54 that is continuous with the second concave groove 52 that is the switching destination and the ball member 43 when switching from the A cam 6A to the B cam 6B. Of the positions of the ball member 43 where a pressing force having an axial component toward the side away from the operation pin 21 is generated as in the case of the first pressing force, the position is closest to the first concave groove 51 that is the switching source. In other words, the second pressing force generation start position is the position of the ball member 43ii in a state where it has started to come in contact with the B inclined surface 54 over the convex portion 55 from left to right in FIG.

  In the present embodiment, the second pressing force generation start position starts from the center Xii of the ball member 43ii and the inclined surface from the center Xii of the ball member 43ii, immediately after the ball member 43 gets over the convex portion 55 from left to right in FIG. It is defined that the line drawn down at the contact point with 54 is a position perpendicular to the inclined surface 54. When the line segment is perpendicular to the inclined surface 54, a second pressing force having the same axial component as the first pressing force is generated in the latter half of the switching period of the cam 6.

  The axial distance that the ball member (43i) fitted in the first concave groove 51 relatively moves to the second pressing force generation start position (43ii) (that is, the second pressing force generation required distance) is ( L / 2) + L ′. Here, (L / 2) is an axial distance in which the ball member (43i) fitted in the first concave groove 51 is relatively moved to the axial position of the convex portion 55 (as described above). In addition, the convex portion 55 is located in the middle between the two concave grooves 51 and 52 in the axial direction. L ′ is an axial distance in which the ball member 43 located at the axial position of the convex portion 55 relatively moves to the second pressing force generation start position (43ii). Here, L ′ is (φ / 2) × when the diameter of the ball member 43 is φ and the inclination angle of the inclined surface 54 (the angle formed by the inclined surface 54 and the axis of the cam element 10) is θ. It is given by sin θ. That is, the required distance for generating the second pressing force is, as shown in the figure, the center Xi of the ball member 43i in a state of being fitted in the first concave groove 51, and the B inclined surface 54 over the convex portion 55. It is defined as the axial distance from the center Xii of the ball member 43ii in a state of starting contact.

  In the present embodiment, the axial protrusion amount K (see FIG. 5) of the axial cam 13a of the end face cam member 13 is formed to a value smaller than the concave groove pitch L. That is, the operation amount of the axial cam 13a is set to a value less than the groove pitch L at the maximum.

  Further, in the present embodiment, the axial protrusion amount K of the axial cam 13a of the end face cam member 13 is formed to be larger than the second required pressing force generation distance (L / 2) + L ′. . That is, the operation amount of the axial cam 13a is set to a value equal to or greater than the second required pressing force generation distance (L / 2) + L ′.

  In the present embodiment, the inclination angle θ of the inclined surfaces 53 and 54 is set to 30 °. That is, the inclined surfaces 53 and 54 are formed at an angle of 30 ° with respect to the axis of the cam element 10.

  Further, in the present embodiment, the electromagnetic valve 20 that advances and retracts the operation pin 21 with respect to the end face cam member 13 is shared by the two cam units 12 adjacent to each other.

  That is, as shown in FIG. 2, one solenoid valve (first cam) is composed of a cam unit (referred to as “first cam unit” hereinafter) 12 and the second cam unit 12 of the first cylinder C1. In FIG. 2, the solenoid valve 20 that moves the unit 12 to the right and moves the second cam unit 12 to the left is shared, and the second cam unit 12 and the third cam unit 12 have one solenoid valve (second cam). 2 share a solenoid valve 20 that moves the unit 12 to the right and moves the third cam unit 12 to the left in FIG. 2, and the third cam unit 12 and the fourth cam unit 12 have one solenoid valve (third cam). The solenoid valve 20) that moves the unit 12 to the right in FIG. 2 and moves the fourth cam unit 12 to the left is shared.

  Note that the solenoid valve 20 that moves the first cam unit 12 to the left in FIG. 2 and the solenoid valve 20 that moves the fourth cam unit 12 to the right are provided independently. That is, a total of five solenoid valves 20 are provided in the four-cylinder engine E according to the present embodiment (referred to as “first solenoid valve 20” to “fifth solenoid valve 20” in order from the right in FIG. 2). The operation pins are called “first operation pin 21” to “fifth operation pin 21” in order from the right).

  FIG. 2 also shows the axial distance between two exhaust valves 2 adjacent to each other per cylinder C, that is, the valve pitch, and the axial distance between cylinders C adjacent to each other, that is, the cylinder pitch. Is shown.

(2) Cam switching operation For example, in FIG. 2, all the solenoid valves 20 are OFF, and all the operation pins (plungers) 21 are retracted (moved upward in FIG. 2) from the end face cam member 13. Is shown. Further, the first cam unit 12 moves to the left in FIG. 2, the second cam unit 12 moves to the right, the third cam unit 12 moves to the left, and the fourth cam unit 12 moves to the right. . As a result, the B cam 6B presses the cam follower 7 in all the cylinders C. That is, the cam units 12 adjacent to each other are arranged in the opposite directions in FIG. Then, the axial interval between the first cam unit 12 and the second cam unit 12 is reduced, and the axial interval between the second cam unit 12 and the third cam unit 12 is increased. The axial interval with the fourth cam unit 12 is narrow.

  From this state, when the second solenoid valve 20 and the fourth solenoid valve 20 are turned ON and the second operation pin 21 and the fourth operation pin 21 move downward in FIG. 2, the second operation pin 21 is in the first state. The cam unit 12 is in contact with the axial cam 13a of the left end cam member 13 and the axial cam 13a of the right end cam member 13 of the second cam unit 12, so that the first cam unit 12 is on the right and the second cam unit 12 is on the right. 12, the fourth operating pin 21 contacts the axial cam 13a of the left end cam member 13 of the third cam unit 12 and the axial cam 13a of the right end cam member 13 of the fourth cam unit 12. Then, the third cam unit 12 is moved to the right and the fourth cam unit 12 is moved to the left. As a result, the switching from the B cam 6B to the A cam 6A is performed in all cylinders C. Then, the axial interval between the first cam unit 12 and the second cam unit 12 is widened, the axial interval between the second cam unit 12 and the third cam unit 12 is narrowed, and the third cam unit 12 The axial distance from the fourth cam unit 12 is increased.

  At this time, the ball member 43 of the detent mechanism 40 of each cam unit 12 relatively moves from the B groove 52 corresponding to the B cam 6B to the A groove 51 corresponding to the A cam 6A. In the present embodiment, the axial protrusion amount K (see FIG. 5) of the axial cam 13a of the end cam member 13 is formed to be smaller than the groove pitch L, but the second pressing force is generated. Since the distance is formed to be larger than the required distance (L / 2) + L ′, the ball member 43 that has escaped from the first concave groove 52 during the relative movement of the ball member 43 starts to generate at least the second pressing force. Until the position is reached, a first pressing force is generated by the contact between the second operating pin 21 and the fourth operating pin 21 and the axial cam 13a, and each cam unit 12 is moved to the second operating pin by the first pressing force. 21 and the fourth operating pin 21 are moved away from each other.

  Next, during the period of relative movement of the ball member 43, the A inclined surface continues to the second concave groove 51 until the ball member 43 that has passed the second pressing force generation start position reaches the second concave groove 51. Since the second pressing force is generated at 53, the second pressing force is generated by the contact between the ball member 43 and the A inclined surface 53, and each cam unit 12 continues to the second operation pin 21 and the second pressing force by the second pressing force. 4 Moved away from the operation pin 21. Since the A inclined surface 53 is formed continuously with the second concave groove 51, the ball member 43 moves from the A inclined surface 53 to the second concave groove 51 while generating the second pressing force, and the second concave groove 51. 51. Thereby, the A cam 6A is positioned on the cam follower 7, and the switching of the cam 6 is completed.

  The end cam member 13 or the axial cam 13a, the operation pin 21, the ball member 43, and the inclined surfaces 53 and 54 constitute cam switching means of the present invention.

(3) Characteristic Configuration As shown in FIG. 5, the valve gear 1 according to the present embodiment includes a collision mitigation mechanism 60 as a collision mitigation means. That is, as described above, the switching of the cam 6 is such that the ball member 43 of the detent mechanism 40 is fitted into the A concave groove 51 or the B concave groove 52, and the axial movement of the cam element 10 or the cam unit 12 is restricted. To finish.

  However, when the moment of movement of the cam element 10 or the cam unit 12 is strong, there is a possibility that the cam element 10 or the cam unit 12 may collide with the bearing portion 30 excessively. Then, noise is generated and the cam element 10, the cam unit 12, and the bearing portion 30 may be damaged.

  In particular, in this embodiment, the ball member 43 slides on the A inclined surface 53 or the B inclined surface 54 and enters the A concave groove 51 or the B concave groove 52 at the final stage of the switching of the cam 6. There is a possibility that the cam unit 10 or the cam unit 12 may continue to move.

  Therefore, in the present embodiment, a collision mitigation mechanism 60 that mitigates collision between the cam element 10 or the cam unit 12 and the bearing portion 30 when the cam 6 is switched is provided.

  Specifically, a circular concave groove 61 centering on the axis of the cam shaft 8 is formed on the surface of the bearing portion 30 facing the cam element 10, and the surface of the cam element 10 facing the bearing portion 30 is A circular ridge 62 centered on the axial center of the cam shaft 8 is formed so as to be fitted into the circular concave groove 61 via oil.

  More specifically, with respect to the right cam element 10 in FIG. 5, a circular ridge 62 is formed in a region overlapping the bearing portion 30 in the radial direction on the left end surface where the end surface cam member 13 is not provided. Corresponding to the ridge 62, a circular groove 61 is formed in a region overlapping the cam element 10 in the radial direction on the right end surface of the bearing portion 30. Similarly, for the left cam element 10 in FIG. 5, a circular ridge 62 is formed in a region overlapping the bearing portion 30 in the radial direction on the right end surface where the end surface cam member 13 is not provided. Corresponding to the stripe 62, a circular groove 61 is formed in a region overlapping the cam element 10 in the radial direction on the left end surface of the bearing portion 30. That is, the collision mitigation mechanism 60 also mitigates the collision between the right cam element 10 and the bearing portion 30, and also mitigates the collision between the left cam element 10 and the bearing portion 30.

  Since oil such as lubricating oil is circulated in the cylinder head in which the valve gear 1 is disposed, oil accumulates in the circular concave groove 61, and the circular concave groove when the cam element 10 and the bearing portion 30 collide with each other. When the circular ridge 62 enters the 61, the oil accumulated in the circular groove 61 serves as a damper, and the impact of the collision is effectively reduced. Therefore, noise caused by the collision and damage to the cam element 10, the cam unit 12, and the bearing portion 30 are suppressed.

(4) Operation, etc. As described above, in this embodiment, the camshaft 8 that rotates in conjunction with the crankshaft of the engine E, and the camshaft 8 that is externally fitted to the camshaft 8 so as to be movable in the axial direction. The cam element 10 includes a cam element 10 including an A cam 6A and a B cam 6B that are integrally rotated along the axial direction of the crankshaft and have different cam profiles. The following configuration is employed in the valve operating apparatus 1 of the engine E including the cam shift mechanism that can switch the valve operating characteristics of the exhaust valve 2 by switching the cam 6 of the cam shaft 5.

  The end face cam member 13 or the axial cam 13a, the operation pin 21, the ball member 43, and the inclined surfaces 53 and 54 constitute cam switching means for switching the cam 6 by moving the cam element 10 in the axial direction. .

  An abutting member, specifically a bearing portion 30, is provided that is disposed on the side where the cam element 10 is close when the cam 6 is switched by the cam switching means. The bearing portion 30 supports the cam element 10 in an axially extending portion 11 provided in the cam element 10 so as to be movable in the axial direction and rotatable in the circumferential direction.

  And the collision mitigation mechanism 60 which relieves the collision with the cam element 10 and the bearing part 30 at the time of switching of the cam 6 by the cam switching means was provided.

  According to the present embodiment, in the valve operating apparatus 1 of the engine E that can switch the valve operating characteristics of the exhaust valve 2 according to the operating state of the engine E, even when the cam 6 is switched, the cam element 10 is connected to the bearing portion 30. Even if a collision occurs, the collision mitigation mechanism 60 mitigates the collision, so that noise caused by the collision and damage to the cam element 10 or the cam unit 12 and the bearing portion 30 are suppressed.

  Moreover, in order to avoid a collision between the cam element 10 and the bearing portion 30, for example, a relatively large clearance is left between the cam element 10 and the bearing portion 30, or a cylindrical groove cam is used instead of the end face cam member 13. Since no members are used, the valve gear 1 can be mounted on a small engine having a relatively short valve pitch or cylinder pitch.

  As described above, according to the present embodiment, in the valve operating device 1 of the engine E that can switch the valve operating characteristics of the exhaust valve 2 according to the operating state of the engine E, the cam element 10 and the bearing portion 30 are caused to collide. Noise and the damage of the cam element 10 or the cam unit 12 and the bearing portion 30 are suppressed, and the axial distance between the cam elements 10 adjacent to each other is shortened, so that the mountability to the engine E is improved.

  Further, in this embodiment, two cam elements 10 are provided in the axial direction with a predetermined interval per cylinder C, and the extension portion 11 connects the two cam elements 10 to each other, and the bearing portion 30. Is arranged between the two cam elements 10, and the collision mitigation mechanism 60 in FIG. 5 also mitigates the collision between the right cam element 10 and the bearing portion 30, and also the collision between the left cam element 10 and the bearing portion 30. ease. That is, the collision alleviating mechanism 60 alleviates the collision between each of the two cam elements 10 and the bearing portion 30.

  According to this configuration, in FIG. 5, for example, when the cam 6 is moved to the left so that the right cam element 10 is close to the bearing portion 30 (switching from the A cam 6A to the B cam 6B). And at the time of switching of the cam 6 in which the cam unit 12 is moved to the right so that the left cam element 10 is close to the bearing portion 30 (at the time of switching from the B cam 6B to the A cam 6A) Noise caused by the collision between the cam element 10 and the bearing portion 30 and damage to the cam element 10 or the cam unit 12 and the bearing portion 30 are suppressed.

  In the present embodiment, the collision mitigation mechanism 60 includes a circular groove 61 centered on the axis of the cam shaft 8 formed on the surface of the bearing portion 30 facing the cam element 10, and the bearing portion of the cam element 10. 30 is formed including a circular ridge 62 centered on the axis of the cam shaft 8 and fitted in the circular concave groove 61 via oil, which is formed on the surface facing the cylinder 30.

  According to this configuration, oil such as lubricating oil accumulates in the circular groove 61 formed in the bearing portion 30, and at the time of collision, the circular ridge 62 formed in the cam element 10 passes through the oil in the circular groove 61. Therefore, the oil accumulated in the circular concave groove 61 serves as a damper, and the impact of the collision is effectively reduced.

  In the present embodiment, the electromagnetic valve 20 that advances and retracts the operation pin 21 relative to the end face cam member 13 is shared by the two cam units 12 adjacent to each other. That is, two electromagnetic valves 20 are not arranged between two cam units 12 adjacent to each other, but only one electromagnetic valve 20 is arranged. Also by this, the axial distance between the cam units 12 adjacent to each other can be shortened, and the valve gear 1 can be mounted on a small engine having a relatively short cylinder pitch.

  In the above embodiment, the circular concave groove 61 is formed in the bearing portion 30 and the circular ridge 62 is formed in the cam element 10.

  Further, the ridge does not have to be connected to a circle. For example, a plurality of arc-shaped ridges or a plurality of dot-like protrusions may be arranged in a circle at intervals.

  In addition, as a component of the collision mitigation mechanism 60, for example, a wave washer, a leaf spring, a coil spring, a rubber plate, a thin plate made of engineering plastic, or the like is interposed between the cam element 10 and the bearing portion 30. May be. In that case, it is preferable to assemble them on the side of the bearing portion 30 that is stationary.

  Moreover, in the said embodiment, although this invention was applied to the valve operating apparatus 1 for the exhaust valve 2, it may replace with this and may apply this invention to the valve operating apparatus for intake valves.

  In the above-described embodiment, the contact member that the cam element 10 may collide with when the cam 6 is switched is the bearing portion 30. However, the contact member is not limited thereto, and the contact member may be a cam when the cam 6 is switched. For example, it may be a rib or a pipe disposed on the side where the element 10 is close.

DESCRIPTION OF SYMBOLS 1 Valve operating apparatus 2 Exhaust valve 5 Exhaust cam shaft 6 Cam 6A A cam 6B B cam 8 Cam shaft 10 Cam element 13 End surface cam member (Cam switching means)
13a Axial cam (cam switching means)
20 Solenoid valve 21 Operation pin (cam switching means)
30 Bearing part (contact member)
31 Support wall 32 Cam cap 40 Detent mechanism 43 Ball member (cam switching means)
51 A groove 52 B groove 53 A inclined surface (cam switching means)
54 B inclined surface (cam switching means)
55 Convex 60 Impact mitigation mechanism (collision mitigation means)
61 Circular groove 62 Circular ridge E Engine K Axial protrusion of axial cam L Groove pitch

Claims (2)

A valve operating device for an engine capable of switching valve operating characteristics of an intake / exhaust valve according to an operating state of the engine,
A cam shaft which rotates in conjunction with the crankshaft of the engine,
A cam element that includes a plurality of cams that are externally fitted to the cam shaft so as to be movable in the axial direction, rotate integrally with the cam shaft, and have cam profiles that are continuously provided along the axial direction of the crankshaft. ,
A cylindrical extension extending from the cam element in the cam axis direction, the central axis being common to the cam shaft and the outer diameter being smaller than the cam element;
A bearing portion that supports the cam element in the extension portion so as to be movable in the axial direction and rotatable in the circumferential direction;
Cam switching means for switching the cam by moving the cam element in the axial direction,
And a shock absorbing means for mitigating collision between the cam element and the bearing portion at the time of switching of the cam by the cam switching means,
The bearing portion is disposed on the side where the cam element is close when the cam is switched by the cam switching means,
The collision mitigation means includes a concave portion formed on one of the opposing surfaces of the cam element and the bearing portion, and a convex portion formed on the other of the opposing surfaces,
An engine in which the outer diameter side portion of the one of the opposing surfaces is more than the outer diameter side portion and the outer diameter side portion of the other of the opposing surfaces is substantially in contact with the concave portion and the convex portion being fitted. Valve gear. The valve gear for an engine according to claim 1,
The concave portion is a circular concave groove centering on an axis of a cam shaft formed on one of the facing surfaces of the cam element and the bearing portion,
The valve operating device for an engine according to the present invention, wherein the convex portion is a convex strip that is fitted into the circular concave groove formed on the other of the opposed surfaces of the cam element and the bearing portion via oil .

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