JP4310265B2 - Engine valve gear - Google Patents

Description

  The present invention relates to a valve operating apparatus for an engine provided with a variable lift mechanism that continuously changes a lift amount of an engine valve that is an intake valve or an exhaust valve.

In order to change the lift amount of the engine valve steplessly, one end of the push rod is fitted to the other end portion of the rocker arm having a valve contact portion that contacts the engine valve on one end side, and the other end of the push rod and A valve operating apparatus in which a link mechanism is provided between valve cams is already known from Patent Document 1.
JP-A-8-74534

  However, in the valve operating apparatus of the engine disclosed in Patent Document 1, it is necessary to secure a relatively large space for arranging the link mechanism and the push rod between the valve operating cam and the rocker arm. Turn into. In addition, since the driving force from the valve cam is transmitted to the rocker arm via the link mechanism and the push rod, it is difficult to say that the follower of the rocker arm with respect to the valve cam, ie, the open / close operation followability of the engine valve is excellent.

  Therefore, the applicant of the present invention has one end portion of the first and second link arms rotatably connected to the rocker arm, and the other end portion of the first link arm is rotatably supported by the engine body. Japanese Patent Application No. 2002-196872 has already proposed a valve operating apparatus for an engine in which the other end is displaced by a driving means. According to this valve operating apparatus, the valve operating apparatus can be made compact. At the same time, the power from the valve cam can be directly transmitted to the rocker arm to ensure excellent followability to the valve cam.

  By the way, in order to reduce the size of the valve operating device, it is important to set the width along the rotation axis of the rocker arm as small as possible, but when opening a pair of engine valves with a single rocker arm, The distance between the engine valves is substantially determined by the shape and size of the combustion chamber, and the width of the valve connecting portion provided on the rocker arm to be connected to both engine valves is also determined according to the distance between the two engine valves. Therefore, in order to reduce the width of the rocker arm as much as possible, it is desirable to configure the rocker arm with the width of the valve connecting portion being maximized.

  The present invention has been made in view of such circumstances, and it is possible to achieve compactness while ensuring followability of the opening and closing operation of the engine after continuously changing the lift amount of the engine valve. An object of the present invention is to provide an engine valve operating device.

In order to achieve the above object, the invention described in claim 1 has a cam abutting portion that abuts on the valve cam, a rocker arm that is linked to and coupled to the engine valve, and one end portion of the rocker arm that is rotatable. A first link arm that is connected and rotatably supported at a fixed position of the engine body, and a movable shaft having one end rotatably connected to the rocker arm and the other end being displaceable A second link arm that is rotatably supported by the motor, and a driving means coupled to the movable shaft so that the position of the movable shaft can be displaced so as to continuously change the lift amount of the engine valve, A valve connecting portion to which a tappet screw that abuts each of the pair of engine valves is screwed so that its advance / retreat position can be adjusted, and first and second supports that rotatably connect one end portions of the first and second link arms. Department and It said rocker arm having found the width of the valve connecting portion in the direction along the rotational axis of the valve operating cam made is formed to be larger than the width of the other portions, a valve operating system for an engine, the first The other end of the one link arm is rotatably supported via a support shaft on a support wall provided in the engine body so as to be disposed on both sides of the other end of the first link arm. Between the other end portion of one link arm and the both support walls, a twist is provided between the engine body and the rocker arm to urge the rocker arm toward the side where the cam contact portion comes into contact with the valve cam. Each of the springs is interposed .

The invention according to claim 2, in addition to the configuration of the invention according to claim 1, wherein the first support portion is formed in a substantially U-shape so as to sandwich the roller which is the cam abutment portion from both sides, The roller is rotatably supported by the first support portion.

According to a third aspect of the present invention, in addition to the configuration of the second aspect of the present invention, a pair of connecting portions sandwiching the first support portion of the rocker arm from both sides are provided at one end portion of the first link arm, two joining portions are pivotally connected to the first support portion through a connecting shaft, characterized in that the roller is axially supported by the first support portion through the connecting shaft.

The invention described in claim 4, in addition to the configuration of the invention according to any one of claims 1 to 3, wherein the first and second support portions, one end portion of the first and second link arms A connecting hole for inserting a connecting shaft for pivotal connection is provided so as to be aligned in the opening / closing operation direction of the two engine valves, and the tangent line that contacts the outer edge of the two connecting holes on the two engine valves side. wherein in the connecting wall and the two engine valves to be at least partially located opposite Te, the between the first and second support portions is connected to its connecting wall, the other end of the second link arm it you wherein a recess is formed at a position opposing the other end of the second link arm closest state to the rocker arm side.

  According to the first aspect of the present invention, it is possible to change the lift amount of the engine valve steplessly by displacing the movable shaft steplessly, and the one end portions of the first and second link arms are rocker arms. It is directly connected to the camshaft so that it can be rotated, and the space for disposing both link arms can be reduced to make the valve operating device more compact. The power from the valve operating cam is directly transmitted to the cam contact portion of the rocker arm. Therefore, excellent followability to the valve cam can be secured. In addition, the rocker arm is for driving the pair of engine valves to open, a valve connecting portion in which tappet screws that respectively contact the both engine valves are screwed so that the advance / retreat position can be adjusted, and the first and second link arms The rocker arm has first and second support portions that rotatably connect one end of the valve, and the rocker arm has a width of the valve connecting portion in the direction along the rotation axis of the valve cam. Therefore, the width of the rocker arm in the direction along the rotation axis of the valve operating cam can be made as small as possible, and this also makes it possible to make the valve operating apparatus more compact.

In addition, since inclusions are interposed between the other end of the first link arm and a support wall provided on the engine body so as to be disposed on both sides of the other end of the first link arm, By selecting the inclusion, the positioning of the first link arm is facilitated so that the dimensional tolerance between the first link arm and the both support walls is absorbed by the inclusion . Further, the inclusion of a torsion spring that urges the rocker arm in the direction in which the cam abutting portion abuts on the valve cam makes it easy to absorb the dimensional tolerances, and the cam abutting portion is connected to the valve cam It is possible to increase the control accuracy of the valve lift amount by reliably bringing it into contact with each other.

According to the second aspect of the present invention, it can be so as to rotatably support the roller in the first support portion formed in a substantially U shape, constituting the entire rocker arm including a roller compact.

According to the third aspect of the present invention, pivotal connection to the first support portion of one end of the first link arm, and achieve journalled to the first support portion of the roller a common connecting shaft In this way, the number of parts can be reduced and the valve gear can be made more compact.

According to the fourth aspect of the present invention, the first and second support portions of the rocker arm, opposite to the engine valve to a tangent in contact with the outer edge of the engine valve side of the pair of connecting holes provided on both support portions Since it is connected by the connecting wall at least partially disposed on the side, the rigidity of the first and second support portions can be increased . In addition, it is possible to displace the other end of the second link arm as close as possible to the rocker arm side, thereby making the valve system more compact and setting the maximum lift of the engine valve as large as possible. It becomes possible to do.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 11 show an embodiment of the present invention. FIG. 1 is a partial longitudinal sectional view of an engine, taken along line 1-1 of FIG. 2, and FIG. 2 is taken along line 2-2 of FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a side view of the variable lift mechanism, FIG. 5 is an exploded perspective view of the variable lift mechanism, and FIG. 6 is a cross sectional view taken along line 6-6 in FIG. 7 is a view taken from the direction of arrow 7 in FIG. 3, FIG. 8 is an explanatory diagram of the operation of the variable lift mechanism, FIG. 9 is a diagram showing the lift curve of the engine valve, FIG. It is a graph which shows the relationship between the rotation angle of an arm, and the rotation angle of a sensor arm.

  First, in FIG. 1, an engine body 10 of an in-line multi-cylinder engine E includes a cylinder block 12 in which cylinder bores 11 are provided, a cylinder head 14 coupled to the top surface of the cylinder block 12, and a cylinder head 14 A head cover 16 coupled to the top surface of each of the cylinders. A piston 13 is slidably fitted to each cylinder bore 11..., And a combustion chamber 15 that faces the top of each piston 13. It is formed between the heads 14.

  The cylinder head 14 is provided with intake ports 17 that can communicate with the combustion chambers 15 and exhaust ports 18 that are opened and closed by intake valves 19 that are a pair of engine valves, respectively. Each exhaust port 18 is opened and closed by a pair of exhaust valves 20. A stem 19 a of the intake valve 19 is slidably fitted to a guide cylinder 21 provided on the cylinder head 14, and between a spring seat 22 provided on the upper end portion of the stem 19 a and a spring seat 23 abutted on the cylinder head 14. Each of the intake valves 19 is urged in the valve closing direction by a valve spring 24 provided in the valve. Further, the stem 20a of the exhaust valve 20 is slidably fitted to a guide cylinder 25 provided on the cylinder head 14, and between the spring seat 26 provided on the upper end portion of the stem 20a and the spring seat 27 abutted on the cylinder head 14. The exhaust valves 20 are urged in the valve closing direction by the valve springs 28 provided in the valve.

  Referring also to FIG. 2, the cylinder head 14 is integrally provided with a holder 44 having support walls 44 a disposed on both sides of each cylinder, and the intake cam holder 46 is provided on each support wall 44 a. ... And caps 45..., 47. Thus, the intake cam shafts 31 are rotatably supported by the intake cam holders 46... And the exhaust cam shafts 32 are rotatably supported by the exhaust cam holders 48. The exhaust valves 20 are driven by the exhaust camshaft 32 via the lift / timing variable mechanism 34.

  The lift / timing variable mechanism 34 for driving the exhaust valves 20 is well known, and the outline thereof will be described here. One end of a pair of low-speed rocker arms 36 and 36 and one end of a single high-speed rocker arm 37 are pivotally supported on the exhaust rocker shaft 35 supported by the support wall 44a of the exhaust cam holder 48. The two low-speed cams 39, 39 provided on the exhaust camshaft 32 abut on the rollers 38, 38 that are pivotally supported on the intermediate portion of the low-speed rocker arms 36, 36, and the high-speed rocker arm 37 has an intermediate shaft. A high speed cam 41 provided on the exhaust camshaft 32 contacts the supported roller 40. Further, tappet screws 42 that are in contact with the upper ends of the stems 20a of the exhaust valves 20 are screwed to the other ends of the low-speed rocker arms 36 so that the advance / retreat position can be adjusted.

  Moreover, both the low-speed rocker arms 36 and 36 and the high-speed rocker arm 37 can be switched between connection and release by hydraulic control, and the low-speed rocker arms 36 and 36 and the high-speed rocker arm 37 can be connected when the engine E operates at low speed. When released, the low-speed rocker arms 36, 36 are driven by the corresponding low-speed cams 39, 39, and the exhaust valves 20 are opened and closed with a low lift and a low opening angle. When the low-speed rocker arms 36 and 36 and the high-speed rocker arm 37 are connected during high-speed operation of the engine E, the high-speed rocker arm 37 is driven by the corresponding high-speed cam 41 and coupled to the high-speed rocker arm 37. 36, the exhaust valves 20 are opened and closed with a high lift and a high opening angle. Thus, the lift and timing of the exhaust valves 20 are controlled in two stages by the lift / timing variable mechanism 34.

  Next, the structure of the variable lift mechanism 33 will be described with reference to FIGS. 3 to 7. The variable lift mechanism 33 serves as a cam contact portion that contacts a valve cam 69 provided on the intake camshaft 31. A rocker arm 63 having a roller 65; a first link arm 61 having one end rotatably connected to the rocker arm 63 and the other end rotatably supported at a fixed position of the engine body 10; and the rocker arm And a second link arm 62 rotatably supported by a movable shaft 68a having one end rotatably connected to 63 and the other end displaceable.

  One end portion of the rocker arm 63 is provided with a valve connecting portion 63a into which tappet screws 70, 70 abutting from above on the upper ends of the stems 19a of the pair of intake valves 19 are screwed so that the forward and backward positions can be adjusted. The other end of the rocker arm 63 is formed in a substantially U shape so as to open to the side opposite to the intake valves 19. The first end for pivotally connecting one end of the first link arm 61. The rocker arm 63 is configured such that the support portion 63b and the second support portion 63c that rotatably connects one end portion of the second link arm 61 are disposed below the first support portion 63b. Provided at the other end. In addition, the roller 65 that is in rolling contact with the valve cam 69 of the intake camshaft 31 is disposed so as to be sandwiched between first U-shaped first support portions 63b. It is coaxially supported by the first support portion 63b.

  The rocker arm 63 is formed by making the width of the valve connecting portion 63a in the direction along the rotational axis of the valve cam 69 larger than the width of the other portions, and the first and second support portions 63b. , 63c are formed to have the same width.

  The first link arm 61 includes a pair of first connecting portions 61a and 61a sandwiching the rocker arm 63 from both sides, a cylindrical fixed support portion 61b, and a pair connecting the first connecting portions 61a and 61a and the fixed support portion 61b. The arm portions 61c and 61c are formed in a substantially U shape.

  The first connecting portions 61 a and 61 a at one end of the first link arm 61 are inserted through and fixed to a first connecting hole 49 provided in the first support portion 63 b of the rocker arm 63. The roller 65 is pivotally connected to the first support part 63 b at the other end of the rocker arm 63, and the roller 65 is also pivotally supported by the first support part 63 b via the first connection shaft 64. In addition, the outer surface of the portion of the first support portion 63b facing the intake camshaft 31 and the outer surfaces of the first connecting portions 61a and 61 in the first link arm 61 are overlapped in a side view so as to overlap the first connecting shaft. It is formed in an arc shape centered on 64 axes.

  The second link arm 62 disposed below the first link arm 61 has a first connecting portion 62a at one end and a movable support portion 62b at the other end, and the second connecting portion 62a The second support portion 63b formed in a substantially U shape is disposed between the second support portions 63b. The second support portion 63c is provided with a second connection hole 50 arranged in the opening / closing operation direction of the intake valves 19, that is, the vertical direction, together with the first connection hole 49 of the first support portion 63b. 62a is rotatably connected to the second support portion 63c via a second connection shaft 66 that is inserted into and fixed to the second connection hole 50.

  That is, one end portion of the rocker arm 63 having the roller 65 in contact with the valve cam 69 on the other end side is linked and connected to the pair of intake valves 19... And the upper first link arm 61 has the first link arm 61 at one end portion. 1 connection part 61a, 61a and the 2nd connection part 62a which the 2nd link arm 62 arrange | positioned under the 1st link arm 61 has in the one end part are arranged in parallel with the other end part of the rocker arm 63 up and down It will be connected so that relative rotation is possible.

  By the way, the rocker arm 63 is integrally provided with a pair of connecting walls 63d connecting the first and second support portions 63b, 63c, which are substantially U-shaped. In addition, the connecting wall 63d is disposed at least partially on the opposite side of the intake valves 19 with respect to the tangent line L contacting the outer edges of the first and second connection holes 49, 50 on the intake valves 19 side. Thus, the first and second support parts 63b and 63c are formed so as to be connected.

  Further, the connecting wall 63d has recesses 51 so that the movable support portion 62b at the other end of the second link arm 62 is disposed at a position facing the movable shaft 68a in a state of being closest to the rocker arm 63 side. It is formed. Further, the connecting wall 63d is formed with a thinned portion 52 so as to be recessed inward from the outer surface, for example.

  The fixed support portion 61b at the other end of the first link arm 61 is formed on the support walls 44a disposed on both sides of the fixed support portion 61b so as to form a lower portion of the intake cam holder 46 provided in the engine body 10. The fixed support shaft 67 is rotatably supported via the fixed support shaft 67, and the fixed support shaft 67 is fixedly supported by the both support walls 44a.

  With particular attention to FIG. 6, a pair of support bosses 53, 53 are integrally projected on the support wall 44 a... So as to protrude toward the fixed support portion 61 b of the first link arm 61. These support bosses 53 are spaced from both end surfaces of the fixed support portion 61b so as to surround the base end portions of the small diameter shaft portions 53a and the small diameter shaft portions 53a. .. Are provided, and the fixed support shaft 67 is fixedly supported by the support bosses 53 so as to penetrate the small diameter shaft portions 53a coaxially.

  The two intake valves 19 are spring-biased in the valve closing direction by the valve springs 24, and the two intake valves 19 spring-biased in the valve closing direction are driven by the rocker arm 63 in the valve opening direction. While the roller 65 of the rocker arm 63 is in contact with the valve cam 69 by the action of the valve springs 24, the spring force of the valve springs 24 is closed when the intake valves 19 are closed. There is a possibility that the roller 65 does not act on the rocker arm 63 and the roller 65 moves away from the valve cam 69, and the control accuracy of the valve lift amount when the intake valves 19 are minutely opened may be reduced. Therefore, it is interposed between both surfaces of the fixed support portion 61b at the other end of the first link arm 61 and support bosses 53 projecting from the support walls 44a disposed on both sides of the fixed support portion 61b. The torsion springs 54 are provided separately from the valve springs 24. The torsion springs 54 urge the rocker arm 63 in the direction in which the roller 65 is brought into contact with the valve cam 69.

  The torsion springs 54 are disposed so as to surround the fixed support shaft 67 via the small-diameter shaft portions 53 a of the support boss 53, and are provided between the engine body 10 and the rocker arm 63. That is, one end of a torsion spring 54 surrounding the small-diameter shaft portion 53a is engaged with a locking pin 55 embedded in a step 53b of the support boss 53, and the other end of the torsion spring 54 ... Are inserted and engaged in a hollow first connecting shaft 64 that operates integrally with the rocker arm 63.

  By the way, the fixed support portion 61b at the other end of the first link arm 61 is cylindrical so that the outer periphery is disposed inwardly in the side view from the outer periphery of the torsion springs 54 wound in a coil shape. A plurality of, for example, a pair of protrusions 56 and 57 for preventing the torsion springs 54 from falling to the fixed support portion 61b side are provided at both ends in the axial direction of the fixed support portion 61b in the circumferential direction. The projections 56 and 57 are provided so as to be spaced apart from each other, and the projections 56 and 57 are disposed so as to avoid the operating range of the second link arm 62.

  In the engine body 10, the first connecting part 61 a... And the second connecting part 62 a at one end of the first and second link arms 61, 62 are connected to the other end of the rocker arm 63 so as to line up and down. Oil jets 58 as oil supply means for supplying oil toward the upper connecting shaft among the first and second connecting shafts 64 and 66 are fixedly arranged. Oil jets 58 that supply oil toward the first connecting shaft 64 that is the upper connecting shaft of the first and second connecting shafts 64 and 66 are caps 45 in the intake cam holders 46 that are provided in the engine body 10. Fixedly mounted on.

  In addition, a first support part 63b formed in a substantially U shape with the roller 65 sandwiched from both sides is provided at the upper part on the other end side of the rocker arm 63, and a first connection part 61a at one end part of the first link arm 61 is provided. Are connected to the first support portion 63b via a first connecting shaft 64 that pivotally supports the roller 65, and the oil jets 58 ... are connected to the first connecting portion 61a of the first link arm 61. ... and the cap 45 ... are arranged so as to supply oil toward the mating surface of the first support part 63b.

  A movable shaft 68 a that rotatably supports a movable support portion 62 b that the second link arm 62 has at the other end is provided on the crank member 68. The crank member 68 is disposed at right angles so that the movable shaft 68a and the support shaft 68c protrude in opposite directions at both ends of a connecting plate 68b disposed in a plane parallel to the operation plane of the second link arm 62. The support shaft 68c is rotatably supported by a support hole 16a provided in the head cover 16 of the engine body 10.

  Thus, when the rocker arm 63 is in the raised position shown in FIG. 4, that is, when the intake valves 19 are closed, the crank member is placed on the axis C of the second connecting shaft 66 that pivotally supports the lower portion of the rocker arm 63. 68 support shafts 68c are arranged coaxially (see FIG. 5). Therefore, when the crank member 68 is swung around the axis of the support shaft 68c, the movable shaft 68a has an arc A (centered on the support shaft 68c). (See FIG. 4).

  The support shaft 68c of the crank member 68 protrudes from the support hole 16a of the head cover 16. A control arm 71 is fixed to the tip of the support shaft 68c, and the control arm 71 is attached to the outer wall of the cylinder head 14. It is driven by an actuator motor 72 as a driving means. That is, the nut member 74 meshes with the screw shaft 73 rotated by the actuator motor 72, and the other end of the connection link 76 that is pivotally supported at one end by the pin 75 on the nut member 74 is connected to the control arm 71 via the pins 77 and 77. Connected to Therefore, when the actuator motor 72 is operated, the nut member 74 moves along the rotating screw shaft 73, and the crank member 68 is moved around the support shaft 68c by the control arm 71 connected to the nut member 74 via the connection link 76. By swinging, the movable shaft 68a moves between the position of FIG. 8 (A) and the position of FIG. 8 (B).

  A rotation angle sensor 80 such as a rotary encoder is provided on the outer wall surface of the head cover 16, and one end of a sensor arm 81 is fixed to the tip of the sensor shaft 80a. The control arm 71 is formed with a guide groove 82 extending linearly along its longitudinal direction, and a connecting shaft 83 provided at the other end of the sensor arm 81 is slidably fitted in the guide groove 82. .

  The screw shaft 73, nut member 74, pin 75, connection link 76, pins 77 and 77, control arm 71, rotation angle sensor 80, sensor arm 81 and connection shaft 83 are walls protruding from the side surfaces of the cylinder block 14 and the head cover 16. A cover 78 housed inside the portions 14a and 16b and covering the end surfaces of the wall portions 14a and 16b is fixed to the wall portions 14a and 16b with bolts 79.

  In the variable lift mechanism 33, when the control arm 71 is rotated counterclockwise from the solid line position of FIG. 3 by the actuator motor 72, the crank member 68 (see FIG. 5) connected to the control arm 71 rotates counterclockwise. As a result, the movable shaft 68a of the crank member 68 rises as shown in FIG. When the roller 65 is pressed by the valve cam 69 of the intake camshaft 31 in this state, the four-bar link connecting the fixed support shaft 67, the first connecting shaft 64, the second connecting shaft 68 and the movable shaft 68a is deformed. The rocker arm 63 swings downward from the chain line position to the solid line position, the tappet screws 70, 70 press the stem 19 a of the intake valve 19, and the intake valve 19 is opened with a high lift.

  When the control arm 71 is rotated to the solid line position in FIG. 3 by the actuator motor 72, the crank member 68 connected to the control arm 71 is rotated in the clockwise direction, and the crank member 68 is movable as shown in FIG. 8B. The shaft 68a is lowered. When the roller 65 is pressed by the valve cam 69 of the intake camshaft 31 in this state, the four-bar link is deformed and the rocker arm 63 swings downward from the chain line position to the solid line position, and the tappet screws 70 and 70 are moved. Presses the stem 19a of the intake valves 19 ..., and the intake valves 19 ... open with low lift.

  FIG. 9 shows a lift curve of the intake air 19 and the opening angle at the time of high lift corresponding to FIG. 8 (A) and the opening angle at the time of low lift corresponding to FIG. 8 (B) are the same. Only the amount is changing. As described above, by providing the variable lift mechanism 33, it is possible to arbitrarily change only the lift amount without changing the opening angle of the intake valves 19.

  By the way, when the actuator motor 72 swings the crank member 68 to change the lift of the intake valves 19..., The magnitude of the lift, that is, the rotation angle of the support shaft 68c of the crank member 68 is detected. It is necessary to feed back to the control. For this purpose, the rotation angle of the support shaft 68c of the crank member 68 is detected by the rotation angle sensor 80. If the rotation angle of the support shaft 68c of the crank member 68 is simply detected, a rotation angle sensor may be directly connected to the support shaft 68c. However, in the low lift region, the intake efficiency is improved by a slight change in the lift amount. Therefore, the rotation angle of the support shaft 68c of the crank member 68 needs to be accurately detected and fed back to the control of the actuator motor 72. On the other hand, in the high lift area, even if the lift amount changes slightly, the intake efficiency does not change greatly, so that a very high accuracy is not required for the detection of the rotation angle.

  The position of the control arm 71 indicated by the solid line in FIG. 10 corresponds to the low lift area, and the position of the control arm 71 indicated by the chain line swung counterclockwise therefrom corresponds to the high lift area. In the low lift region, the connecting shaft 83 of the sensor arm 81 fixed to the sensor shaft 80a of the rotation angle sensor 80 is engaged with the distal end side (the side far from the axis C) of the guide groove 82 of the control arm 71. The sensor arm 81 swings greatly only by slightly swinging the control arm 71. That is, the ratio of the rotation angle of the sensor shaft 80a to the rotation angle of the crank member 68 is increased, the resolution of the rotation angle sensor 80 is increased, and the rotation angle of the crank member 68 can be detected with high accuracy.

  On the other hand, in the high lift region where the control arm 71 swings to the position indicated by the chain line, the connecting shaft 83 of the sensor arm 81 fixed to the sensor shaft 80a of the rotation angle sensor 80 is on the proximal end side of the guide groove 82 of the control arm 71. Since it is engaged with (the side close to the axis C), the sensor arm 81 swings only slightly even if the control arm 71 swings greatly. That is, the ratio of the rotation angle of the sensor shaft 80a to the rotation angle of the crank member 68 is reduced, and the detection accuracy of the rotation angle of the crank member 68 is lower than that during low lift.

  As is apparent from the graph of FIG. 11, when the rotation angle of the control arm 71 increases from the low lift state to the high lift state, the detection accuracy increases because the angle increase rate of the sensor arm 81 is high at first. Although it becomes high, it turns out that the said increase rate becomes low gradually and detection accuracy falls.

  As described above, the low lift that requires high detection accuracy is achieved by engaging the sensor arm 81 of the rotation angle sensor 80 with the guide groove 82 of the control arm 71 without using an expensive rotation angle sensor with high detection accuracy. The detection accuracy in the state can be ensured and the cost can be reduced.

  At this time, one end side of the control arm 71 (side closer to the support shaft 68 c) and one end side of the sensor arm 81 (side closer to the rotation angle sensor 80) are arranged close to each other, and a guide groove is formed on one end side of the control arm 71. Since 82 is formed, the length of the sensor arm 81 can be shortened and made compact. Further, if the guide groove 82 is formed on one end side of the control arm 71, the distance from the axis C is reduced, and the amount of movement of the guide groove 82 in the circumferential direction is reduced, but the length of the sensor arm 81 is also shortened. A sufficient rotation angle of the arm 81 can be secured to ensure the detection accuracy of the rotation sensor 80.

  Next, the operation of this embodiment will be described. In the lift variable mechanism 33 for continuously changing the valve opening lift amount of the intake valves 19..., The first and second link arms 61 and 62 have at one end thereof. The first and second connecting portions 61a, 61a; 62a are capable of relative rotation in parallel with the other end portion of the rocker arm 63 having a valve connecting portion 63a connected to and connected to the pair of intake valves 19. The fixed support portion 61 b connected to the other end of the first link arm 61 is rotatably supported by a fixed support shaft 67 supported by the engine body 10, and the movable support portion at the other end of the second link arm 62. 62b is rotatably supported by a movable shaft 68a that can be displaced.

  Therefore, the lift amount of the intake valves 19 can be changed steplessly by displacing the movable shaft 68a steplessly, and one end portions of the first and second link arms 61 and 62 are rotated to the rocker arm 63. It is directly connected so as to be movable, and the space for arranging both link arms 61 and 62 can be reduced, so that the valve operating device can be made compact. The power from the valve operating cam 69 is directly applied to the roller 65 of the rocker arm 63. Since it is transmitted, excellent followability to the valve cam 69 can be ensured. Further, the rocker arm 63 and the first and second link arms 61 and 62 in the direction along the axis of the intake camshaft 31 can be disposed at substantially the same position, and the movement in the direction along the axis of the intake camshaft 31 can be performed. The valve device can be made compact.

  In addition, tappet screws 70 that abut against the pair of intake valves 19 are rotatable about a valve connecting portion 73a that is screwed so that the advance and retreat positions thereof can be adjusted, and one end portions of the first and second link arms 61 and 62. The rocker arm 63 having the first and second support parts 63b and 63c connected to the valve connecting part 63a is formed such that the width of the valve connecting part 63a in the direction along the rotational axis of the valve cam 69 is larger than the width of other parts. Therefore, the width of the rocker arm 63 in the direction along the rotational axis of the valve cam 69 can be made as small as possible, and this also makes it possible to make the valve gear compact. In addition, since the rocker arm 63 is formed with the same width of the first and second support portions 63b and 63c, the rocker arm 63 can be made compact while simplifying its shape.

  Further, the first support portion 63b provided on the rocker arm 63 is formed in a substantially U shape so as to sandwich the roller 65 from both sides, and the roller 65 is rotatably supported by the first support portion 63b. The entire rocker arm 63 can be configured compactly. Moreover, one end of the first link arm 61 is provided with a pair of first connecting portions 61 a that sandwich the first support portion 63 b from both sides, and both the first connecting portions 61 a are connected via the first connecting shaft 64. Since the roller 65 is pivotally connected to the first support part 63b via the first connection shaft 64, the first support part 63b is pivotally connected to the first support part 63b. The pivotable connection of the roller 65 and the shaft support of the roller 65 to the first support portion 63b are achieved by the common first connection shaft 64, thereby reducing the number of parts and making the valve operating device more compact. Can be

  First and second connection shafts 64 and 66 for rotatably connecting one end portions of the first and second link arms 61 and 62 to the first and second support portions 63b and 63c of the rocker arm 63, respectively. First and second connection holes 49 and 50 to be inserted are provided so as to be aligned in the opening / closing operation direction of both intake valves 19..., And the first and second connection holes 49 and 50 are provided on both intake valves 19. Since the first and second support portions 63b, 63c are connected by a connecting wall 63d, at least a part of which is disposed on the opposite side of the tangent L that contacts the outer edge of the intake valve 19, ... The rigidity of the 1st and 2nd support parts 63b and 63c can be improved. .

  Further, a recess 51 is formed in the connecting wall 63d so that the second connecting portion 62a at the other end of the second link arm 62 faces the second connecting portion 62a with the second connecting portion 62a closest to the rocker arm 63 side. Thus, the second connecting portion 62a of the second link arm 62 can be displaced to a position as close as possible to the rocker arm 63 side, so that the maximum lift of the intake valves 19 can be reduced while making the valve gear compact. It becomes possible to set the amount as large as possible.

  Further, since the thinned portions 52 are formed in the connecting walls 63d, it is possible to suppress an increase in the weight of the rocker arm 63 while enabling an increase in rigidity due to the connecting walls 63d.

  An oil jet 58 for supplying oil toward the upper first connecting shaft 64 side of the first and second connecting shafts 64, 66 connecting one end of the first and second link arms 61, 62 to the rocker arm 63. Is fixed to the engine body 10, and the oil lubricated between the upper first link arm 61 and the rocker arm 63 out of the first and second link arms 61, 62 flows down to the lower second link arm. 62 and the rocker arm 63 are lubricated. Therefore, the lubrication structure with a simple and reduced number of parts can lubricate the connecting portions of the rocker arm 63 and the first and second link arms 61 and 62 together to ensure smooth valve operation.

  In addition, the rocker arm 63 is provided with a first support portion 63b formed in a substantially U shape so as to sandwich the roller 65 from both sides, and the first connecting portion 61a at one end of the first link arm 61 The oil jet 58 is supplied to the first link arm 61 and the first support portion 63b at the mating surface by being rotatably connected to the first support portion 63b via the supporting first connection shaft 64. In this way, since the engine body 10 is disposed, the shaft support portion of the roller 65 can also be lubricated.

  Further, since the intake camshaft 31 provided with the valve cam 69 is rotatably supported, the oil jets 58 are disposed on the caps 45 of the intake cam holders 46 provided on the engine body 10. A sufficiently high pressure and a sufficient amount of oil can be supplied from the oil jets 58 using an oil passage for lubricating the shaft 31 and the intake cam holders 46.

  Incidentally, the intake valves 19 are urged in the valve closing direction by the valve springs 24. However, the rocker arm 63 causes the roller 65 to strike the valve cam 69 by a torsion spring 54 different from the valve springs 24. The roller 65 of the rocker arm 63 does not move away from the valve operating cam 69 even when the intake valves 19 are closed, and the valve lift amount is controlled when the intake valves 19 are minutely opened. The accuracy can be increased.

  Further, the torsion springs 54 are coiled torsion springs surrounding the fixed support shaft 67, and the installation space for the torsion springs 58 can be reduced, and the valve operating device can be made compact.

  Moreover, a pair of support bosses 53, 53 for supporting the fixed support shaft 67 are provided on the support wall 44a of the intake cam holder 46 of the engine body 10 so as to sandwich the other end of the first link arm 61 from both sides, and a torsion spring. 54... Surround the support bosses 53, 53 and are interposed between the support wall 44 a of the engine body 10 and the other end of the first link arm 61, so that the first link arm 61 and both support walls The first link arm 61 is easily positioned by absorbing the dimensional tolerance between 44a ... by the torsion springs 54 ..., and the fixed support portion at the other end of the first link arm 61 is supported by the pair of support bosses 53, 53. The compact of the torsion springs 54 is controlled so as to avoid the influence of the contraction of the torsion springs 54 on the fixed support shaft 67 while restricting the movement of the 61b. Arrangement is possible.

  The other end portion of the first link arm 61 is provided with a cylindrical fixed support portion 61b whose outer periphery is arranged inwardly of the outer periphery of the torsion springs 54 in a side view, and the fixed support portion 61b. Is supported by the fixed support shaft 67 so as to be rotatable, and a plurality of protrusions that prevent the torsion springs 54 ... from falling on the fixed support portion 61b side at both axial ends of the fixed support portion 61b. 56, 57... Project from the circumferential direction at intervals. Therefore, it is possible to prevent the torsion springs 54 from falling while suppressing an increase in size of the fixed support portion 61b, and to increase the support rigidity of the fixed support portion 61b.

  In addition, since the protrusions 56, 57... Are arranged to avoid the operating range of the second link arm 62, the protrusions 56, 57. A sufficient operating range can be secured.

  Further, the variable lift mechanism 33 includes a crank member 68 formed by projecting a movable shaft 68a and a support shaft 68c having an axis parallel to the movable shaft 68a at both ends of the connecting plate 68b. Is pivotally supported by the head cover 16 of the engine body 10, the movable shaft 68 a can be easily displaced by rotating the crank member 68 around the axis of the support shaft 68 c, and the actuator motor 72 is movable. The mechanism for displacing the shaft 68a can be simplified.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

FIG. 3 is a partial longitudinal sectional view of the engine, taken along line 1-1 of FIG. FIG. 2 is a sectional view taken along line 2-2 of FIG. FIG. 3 is a view taken along line 3-3 in FIG. 2. It is a side view of a lift variable mechanism. It is a disassembled perspective view of a lift variable mechanism. FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. FIG. 7 is a view taken in the direction of arrow 7 in FIG. 3. It is operation | movement explanatory drawing of a lift variable mechanism. It is a figure which shows the lift curve of an engine valve. It is a principal part enlarged view of FIG. It is a graph which shows the relationship between the rotation angle of a control arm, and the rotation angle of a sensor arm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Engine main body 19 ... Intake valve 44a as an engine valve ... Support walls 49, 50 ... Connection hole 51 ... Recess 52 ... Meat removal part 54 ... Inclusion Torsion spring 61 ... first link arm 61a ... connecting part 62 ... second link arm 63 ... rocker arm 63a ... valve connecting part 63b ... first support part 63c ... second Support part 63d ... connecting walls 64, 66 ... connecting shaft 65 ... roller 67 as cam contact part ... support shaft 68a ... movable shaft 69 ... valve operating cam 70 ... Tappet screw 72 ... Actuator motor E as drive means ... Engine L ... Tangent

Claims (4)

A rocker arm (63) that has a cam contact portion (65) that contacts the valve cam (69) and that is linked to and connected to the engine valve (19), and one end portion of which is rotatably connected to the rocker arm (63). A first link arm (61) whose other end is rotatably supported at a fixed position of the engine body (10), and one end is rotatably connected to the rocker arm (63). The second link arm (62) rotatably supported by a movable shaft (68a) whose end is displaceable, and the movable shaft (68a) of the movable shaft (68a) to continuously change the lift amount of the engine valve (19). Drive means (72) connected to the movable shaft (68a) to enable displacement of the position, and tappet screws (70) respectively contacting the pair of engine valves (19) to adjust their advance / retreat positions. Valve to be screwed The rocker arm (63) having a linking portion (63a) and first and second support portions (63b, 63c) that rotatably connect one end portions of the first and second link arms (61, 62). A valve operating device for an engine, wherein the valve connecting portion (63a) in the direction along the rotational axis of the valve operating cam (69) is formed to have a width larger than that of other portions ,
On the support wall (44a) provided on the engine body (10) such that the other end of the first link arm (61) is disposed on both sides of the other end of the first link arm (61). It is rotatably supported via a support shaft (67), and the engine body (10) and the rocker arm (63) are provided between the other end of the first link arm (61) and the support walls (44a). ) And a torsion spring (54) for urging the rocker arm (63) on the side where the cam contact portion (65) contacts the valve cam (69). valve operating equipment of the engine, characterized. The first support part (63b) is formed in a substantially U shape so as to sandwich the roller (65) as the cam contact part from both sides, and the roller (65) can be rotated by the first support part (63b). The valve operating apparatus for an engine according to claim 1 , wherein the valve operating apparatus is supported by the engine. Wherein the one end of the first link arm (61), said rocker arm (63) a pair of connecting portions which sandwich the first support portion (63 b) from both sides of (61a) is provided, connecting the two connecting portions (61a) is The roller (65) is pivotally connected to the first support part (63b) via the connection shaft (64). The roller (65) is pivotally connected to the first support part (63b) via a shaft (64). The valve operating apparatus for an engine according to claim 2 . Said first and second support portions (63 b, 63c), said connecting shaft for one end of the connecting rotatably the respective first and second link arms (61, 62) and (64, 66) Connection holes (49, 50) to be inserted are provided so as to be aligned in the opening / closing operation direction of the two engine valves (19), and on the outer edges of the two connection holes (49, 50) on the two engine valves (19) side. at least in part connecting wall arranged (63d), said first and second support portions (63b, 63c) between the connecting on the opposite side of the tangent the two engine valves with respect to (L) (19) in contact with In the connecting wall (63d), the second link arm (62) is opposed to the other end of the second link arm (62) with the other end of the second link arm (62) closest to the rocker arm (63). A recess (51) is formed in the first portion. The valve operating equipment of the engine according to any one of to 3.

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