JP2008051048A - Valve mechanism of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the wear of a lost motion lifter from being concentrated in a narrow range. <P>SOLUTION: A variable valve mechanism 9 comprises an input portion 21 and an output portion 26 which are swingingly arranged on the same axis line so as to be able to adjust a relative rotational phase difference G with each other, and a lost motion mechanism 41 to energize the input portion 21 to a rotation cam 10. As the rotation cam 10 rotates, the input portion 21 and the output potion 26 integrally swing so as to open and close a valve 8 in the output portion 26. The lost motion mechanism 41 is configured to include the lost motion lifter 42 brought in contact with the input portion 21, a coil spring 43 to press the lost motion lifter 42 against the input portion 21, and a ratchet mechanism 46 to rotate the lost motion lifter 42 in a one-way direction by taking a rotating force out of rotation forces into both circumferential directions P, Q generated by circumferential torsion caused in the dynamic compression of the coil spring 43 and a return of the circumferential torsion caused in dynamic expansion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a valve operating mechanism for driving a valve of an internal combustion engine.

The valve mechanism includes a valve lifter 82 attached to the stem end of the valve 8 as in the conventional valve mechanism 80 shown in FIG. 6A, and the rotating cam 81 directly connects the valve lifter 82. Between the rotary cam 91 and the valve 8, like a direct hitting type that opens and closes the valve 8 by pressing (Patent Document 1) and a variable valve mechanism 90 of the conventional example 2 shown in FIG. The input portion 92 and the output portion 94 as swing members that are arranged so as to be swingable side by side on the same axis, and the relative rotation phase difference G between the input portion 92 and the output portion 94 can be variably adjusted. And a lost motion mechanism 96 that urges the input unit 92 to the rotating cam 91. When the rotating cam 91 rotates, the input unit 92 and the output unit 94 swing together. The valve 8 is opened and closed by the output unit 94 Those striking type (Patent Document 2).
Japanese Patent Laid-Open No. 6-17611 JP 2001-263015 A

  In the above two conventional examples, the rotary cam 81 and the arm 93 of the input unit 92 are generally placed at the center of the valve lifter 82 and the lost motion lifter 97, respectively. As shown in FIG. 6B and FIG. 6D, the wears f1 and f2 are concentrated at the same position in the center of the valve lifter 82 and the lost motion lifter 97, respectively.

  Therefore, in the valve mechanism 80 of the first conventional example, as shown in FIG. 7A, the rotary cam 81 causes the valve lifter 82 to be offset by offsetting the position of the rotary cam 81 from the center of the valve lifter 82 by the width w1. There is also known one in which a rotational force is applied to the valve lifter 82 when pressing.

  According to the above method, by applying the rotational force and gradually rotating the valve lifter 82, as shown in FIG. 7B, the portion where the wear f3 occurs is spread over the entire upper surface of the valve lifter 82, so that the wear is prevented. Although it is possible to prevent concentration in a narrow range, a method similar to this cannot be employed in the variable valve mechanism 90 of the second conventional example. This is because the lost motion lifter 97 of the variable valve mechanism 90 urges the arm 93 of the input portion 92 as a swinging swinging member, and as shown in FIG. Even if the position of the lost motion lifter 97 is offset by the width w2 with respect to the central portion of the arm 93, the lost motion lifter 97 cannot be given a rotational force having a direction in one direction. This is because the motion lifter 97 only swings in the circumferential direction within a minute range, and as shown in FIG. 7 (d), the wear f4 is concentrated in a narrow range.

  Therefore, an object is to prevent the wear of the lost motion lifter that biases the swing member from being concentrated in a narrow range.

In order to achieve the above object, a valve operating mechanism for an internal combustion engine according to the present invention includes a swinging member that is swingably interposed between a rotating cam and a valve, and biases the swinging member to the rotating cam. A valve mechanism of an internal combustion engine that opens and closes the valve by swinging the swinging member when the rotating cam rotates.
The lost motion mechanism is generated when a lost motion lifter that comes into contact with the swing member, a coil spring that presses the lost motion lifter against the swing member, and a circumferential twist and elastic extension that occur when the coil spring is elastically compressed. It includes a ratchet mechanism that takes out one of the rotational forces in both circumferential directions due to the return of the circumferential twist and rotates the lost motion lifter in one direction.

  The valve mechanism is not particularly limited, but it is preferably employed in a variable valve mechanism that can change the opening / closing amount of the valve. This is because the necessity of interposing a swing member between the rotating cam and the valve is high for such a variable valve mechanism.

  Further, at this time, the variable valve mechanism is not particularly limited, but the input part and the output part as the swinging member provided side by side on the same axis, and the input part and the output part between them. A rotation phase difference variable mechanism engaged so that the relative rotation phase difference can be variably adjusted, and when the rotating cam rotates, the input unit and the output unit are integrally swung and the output unit It is preferable to open and close the valve.

  According to the present invention, by providing a ratchet mechanism and rotating the lost motion lifter in one direction, the wear of the lost motion lifter can be prevented from being concentrated in a narrow range.

  The variable valve mechanism 9 for an internal combustion engine of the present invention includes an input portion 21 and an output portion 26 as swing members interposed between the rotary cam 10 and the valve 8 so as to be swingable side by side on the same axis, A rotation phase difference variable mechanism 31 in which the input unit 21 and the output unit 26 are engaged so that the relative rotation phase difference G between the input unit 21 and the output unit 26 can be varied and adjusted, and a lost motion mechanism 41 that biases the input unit 21 to the rotating cam 10. When the rotary cam 10 rotates, the input unit 21 and the output unit 26 swing together to open and close the valve 8 at the output unit 26.

  The lost motion mechanism 41 includes a lost motion lifter 42 that abuts the input unit 21, a coil spring 43 that presses the lost motion lifter 42 against the input unit 21, and a circumferential torsion and elastic extension that occur when the coil spring 43 is elastically compressed. It includes a ratchet mechanism 46 that takes out one of the rotational forces in both circumferential directions P and Q caused by the return of the circumferential twist generated, and rotates the lost motion lifter 42 in one direction.

  The variable valve mechanism 9 shown in FIG. 1 and FIG. 2 of the first embodiment is a mechanism that continuously changes the valve opening / closing amount in accordance with the operating state of the internal combustion engine. It is attached to the valve 8 for use. Specifically, there is one variable valve mechanism 9 for each cylinder 6, and each variable valve mechanism 9 is installed in the cylinder head 7 for each cylinder 6, and the intake valve described above. Two 8 are pressed simultaneously.

  The variable valve mechanism 9 includes a rotary cam 10 that is rotationally driven as the internal combustion engine 5 is operated, a rocker arm 15 that swings when the power is transmitted, and opens and closes the valve 8, and the rotary cam 10 and the rocker arm 15. An intermediate drive mechanism 20 that adjusts the amount of opening and closing of the valve 8 by transmitting the power from the rotary cam 10 to the rocker arm 15 in a variable amount is interposed therebetween.

  The rotating cam 10 is formed on a camshaft 10 x that is rotatably installed above the cylinder head 7, and includes a base circle portion 11 that is a basic portion and a cam nose 12 that protrudes from the base circle portion 11. Has been. A cam surface 10 s for pressing the mediating drive mechanism 20 is formed on the outer peripheral surface of the rotating cam 10.

  There are two rocker arms 15 for each variable valve mechanism 9, and one rocker arm 15 is installed for each valve 8. Each rocker arm 15 has a base end portion 15 a supported by the lash adjuster 17 so as to be swingable, and a tip end portion 15 b abutting against the stem end 8 e of the valve 8. A roller 16 that is pressed by the mediating drive mechanism 20 is pivotally attached to the intermediate portion of the rocker arm 15.

  The intermediary drive mechanism 20 includes an input portion 21 and an output portion 26 as swing members supported in a swingable manner along the same support pipe 20x between the rotary cam 10 and the rocker arm 15, and the input portion 21 and the output. A rotation phase difference variable mechanism 31 that engages the portion 26 so that the relative rotation phase difference G between the two can be varied, and a lost motion mechanism 41 that biases the input portion 21 toward the rotary cam 10. ing. The intermediate drive mechanism 20 is configured such that when the rotary cam 10 rotates, the input unit 21 and the output unit 26 integrally swing to open and close the valve 8 at the output unit 26. If the relative rotation phase difference G between the input unit 21 and the output unit 26 is changed by the rotation phase difference variable mechanism 31, the opening / closing amount of the valve 8 can be changed. In the following description, one of the length directions of the support pipe 20x is defined as the front F and the other is defined as the rear R, and the output unit 26 drives the rocker arm 15 and opens the valve 8 in the circumferential direction of the support vip 20x. The direction on the side is the opening direction O, and the direction on the opposite side is the closing direction C.

  The support pipe 20 x is a single pipe shared by the plurality of variable valve mechanisms 9, and rotates around the plurality of standing wall portions 7 v arranged in parallel at intervals in the front-rear directions F and R on the upper portion of the cylinder head 7. It is fixed immovable. And between two of the plurality of standing wall portions 7v, the input portion 21 and the output portion 26 of one variable valve mechanism 9 are supported side by side with their end surfaces aligned with each other. The input portion 21 and the output portion 26 are prevented from moving in the front-rear directions F and R by having both ends of the arrangement abut against the standing wall portions 7v on both sides.

  The input part 21 is disposed at a substantially center between the standing wall parts 7v. The input unit 21 includes a cylindrical base circle 22 serving as a basic part, an input arm 23 that supports an input roller 24 that contacts the rotating cam 10, and a return arm 25 that is pressed by a lost motion mechanism 41. A shaft hole for inserting the support pipe 20x and the rotation phase difference variable mechanism 31 is formed at the center of the base circle 22. Two input arms 23 are formed so as to protrude in parallel to the outer peripheral surface of the base circle portion 22, and the above-described input roller 24 is axially attached via a shaft 24 x between the tips of the input arms 23. Yes. The return arm 25 is formed on the opposite side of the radial direction of the input portion 21 with respect to both the input arms 23. When the return arm 25 is urged in the closing direction C by the lost motion mechanism 41, the input is performed. The roller 24 is always in contact with the cam surface 10 s of the rotating cam 10.

  The output unit 26 is disposed one by one on both sides in the front-rear direction F, R of the input unit 21. Each output portion 26 includes a base circle portion 27 serving as a basic portion and an output nose 29 having an output cam surface 29 s for pressing the rocker arm 15. A support portion is provided at the center of the base circle portion 27. A shaft hole through which the pipe 20x and the rotation phase difference variable mechanism 31 are inserted is formed. Moreover, the bearing part 28 provided with the center hole for inserting the support pipe 20x in each end surface on the opposite side to the input part 21 side of each output part 26 is provided. The output nose 29 of each output portion 26 is formed so as to protrude from the outer peripheral surface of the base circular portion 27, and the above-mentioned output cam curved in a concave shape is formed on the outer peripheral surface on the opening direction O side from the top of the output nose 29. A surface 29s is formed.

  The rotation phase difference variable mechanism 31 includes a slider gear 32 in which helical splines having different angles are engaged with each other between the input unit 21 and the output unit 26, and a control that slides in the front and rear directions F and R in the support pipe 20x. The shaft 33 includes a connecting mechanism 34 that restrains the slider gear 32 to the control shaft 33 in the front and rear directions F and R and is slidably connected in the opening and closing directions O and C.

  The lost motion mechanism 41 includes a lost motion lifter 42 that contacts the input unit 21, a coil spring 43 that presses the lost motion lifter 42 against the input unit 21 at the distal end portion 43 b, and a support unit that supports the base end portion 43 a of the coil spring 43. 44 and a connecting frame 45 in which the support portion 44 is connected and fixed to the standing wall portions 7v on both sides in the front-rear direction F and R. Further, between the lost motion lifter 42 and the tip 43b of the coil spring 43, the circumferential twist caused by the elastic compression of the coil spring 43 and the circumferential directions P and Q due to the return of the circumferential twist caused by the elastic extension. A ratchet mechanism 46 is provided that takes out one of the rotational forces and rotates the lost motion lifter 42 in one direction.

  The lost motion lifter 42 is a bottomed cylindrical member, and the distal end side of the coil spring 43 is inserted into the cylindrical hole, and the inner bottom surface 42n of the cylindrical hole is pressed against the distal end portion 43b of the spring. Thus, the end face 42e on the back side of the inner bottom face 42n is pressed against the return arm 25 of the input unit 21.

  The coil spring 43 is a coiled spring that spirally turns. The base end portion 43a is supported by the support portion 44 so as not to rotate, and the distal end portion 43b is brought into contact with the inner bottom surface 42n of the lost motion lifter 42. Yes. The tip portion 43b is not seated, and has an end face 43e that stands substantially perpendicular to the winding direction of the spring. When the coil spring 43 is elastically compressed in the length directions V and W, a circumferential twist in the circumferential directions P and Q occurs, and the tip end portion 43b slightly rotates in one circumferential direction P. When the elastic extension extends again in the length directions V and W, the circumferential twist returns, and the tip end portion 43b slightly rotates in the other circumferential direction Q. In the following description, the one circumferential direction P is referred to as a twist direction P, and the other circumferential direction Q is referred to as a return direction Q.

  The support portion 44 supports the proximal end portion 43a of the coil spring 43 that presses the lost motion lifter 42 at the distal end portion 43b, and wraps the lost motion lifter 42 from the side so that the lost motion lifter 42 is coiled. 43 is a cylindrical member supported in the length directions V and W so as to be displaceable in accordance with the expansion and contraction of the spring and in a direction orthogonal to the length directions V and W. Specifically, the support portion 44 is a bottomed cylindrical member that supports the base end portion 43a of the coil spring 43 on the inner bottom surface 44n, and is integrally formed with the connecting frame 45 that extends in the front-rear directions F and R. The both ends of the connecting frame 45 in the front-rear direction F, R side are supported by the standing wall portions 7v on both sides, so that the support portion 44 is supported so as not to move relative to the cylinder head 7.

  The ratchet mechanism 46 engages the lost motion lifter 42 with the distal end portion 43b so as not to move relative to the distal end portion 43b when the distal end portion 43b of the coil spring 43 is slightly rotated in the twisting direction P. When rotating slightly to Q, by allowing the tip 43b to move relative to the lost motion lifter 42 in the return direction Q, the loft motion lifter 42 is twisted in the twisting direction P as the coil spring 43 expands and contracts. It is a mechanism that rotates it.

  Specifically, the ratchet mechanism 46 includes a plurality of ratchet teeth 47 arranged in a circumferential manner along the outer peripheral portion of the inner bottom surface 42n of the lost motion lifter 42. The plurality of ratchet teeth 47 are coil springs. When 43 is pressed by the input unit 21 and compressed, one end is provided for each length range that is substantially equal to or slightly smaller than the stroke at which the tip 43b of the spring rotates slightly. Each ratchet tooth 47 is engaged with the tip end portion 43b of the coil spring 43 so as not to be relatively movable in the twisting direction P on the return direction Q side. On the twisting direction P side, the surface 48 is provided with an inclined surface 49 inclined at a relatively gentle angle with respect to the return direction Q, which allows the tip portion 43b to move relative to the return direction Q. Yes.

  When the variable valve mechanism 9 shown above rotates the lost motion lifter 42 when opening and closing the valve 8, the base circle 11 of the rotating cam 10 touches the input roller 24 (1). (2) When the input unit 21 rotates in the opening direction O from when the cam nose 12 starts to hit the input roller 24 until the top of the cam nose 12 hits, and when the input roller 24 A description will be given below of (3) the rotation of the input unit 21 in the closing direction C from the time when the top part comes into contact until the base circle part 11 comes into contact again.

(1) When the input unit 21 is stationary Since the input unit 21 does not move in the opening / closing directions O and C, the lost motion lifter 42 and the coil spring 43 are stationary without moving as shown in FIG. At this time, the tip 43b of the coil spring 43 is positioned between one ratchet tooth 47i and one ratchet tooth 47j adjacent to the return direction Q side.

(2) When the input unit 21 rotates in the opening direction O As the input unit 21 rotates in the opening direction O, the lost motion lifter 42 is pressed by the return arm 25 as shown in FIG. The coil spring 43 is compressed in the length directions V and W. At this time, the distal end portion 43b of the coil spring 43 slightly rotates in the twisting direction P, and accordingly, the end surface 43e of the distal end portion 43b presses the locking surface 48 of the one ratchet tooth 47i in the twisting direction P. Thus, the lost motion lifter 42 is slightly rotated in the twist direction P by one ratchet tooth 47 or a stroke slightly larger than that.

(3) When the input unit 21 is rotated in the closing direction C As shown in FIG. 3C, the input unit 21 is rotated in the closing direction C, and is lost and compressed by the return arm 25. The motion lifter 42 expands again. At this time, the distal end portion 43b of the coil spring 43 slides along the inclined surface 49 of the ratchet teeth 47j located next to the return direction Q side of the ratchet teeth 47i pressed in (2), thereby causing the lost motion lifter. Independently from 42, it slightly rotates in the return direction Q. Finally, as shown in FIG. 3 (d), the ratchet teeth 47j are overcome and one ratchet tooth 47j is returned. It moves between the adjacent ratchet teeth 47k on the direction Q side.

  By repeating the operations (1), (2), and (3), the lost motion lifter 42 is gradually rotated in the twisting direction P every time the coil spring 43 contracts.

  According to this embodiment, the ratchet mechanism 46 is provided and the lost motion lifter 42 is rotated in the twisting direction P as shown in FIG. 4A. If there is no such rotation, as shown in FIG. In addition, the wear f0 of the end face 42e of the lost motion lifter 42 is concentrated in a narrow range. As shown in FIG. 4C, the wear f of the end face 42e is dispersed in the rotation direction, and the wear f Can be prevented from concentrating on a narrow area. At the same time, also on the side surface 42 s of the lost motion lifter 42, the rotation is not pressed against the inner peripheral surface of the support portion 44 by sliding friction from the return arm 25 as shown in FIG. As shown in FIG. 4C, the wear g0 is concentrated only on the protruding direction side of the return arm 25 on the side surface 42s, and the wear g is dispersed along the side surface 42s in the rotational direction. The wear g can be prevented from being concentrated in a narrow range.

  Further, if such a rotation method using the ratchet mechanism 46 is used, there is no need to offset the position of the lifter as in the conventional example, and therefore, the center of the lost motion lifter 42 is placed at the center of the load applied from the return arm 25. Can be combined.

  The variable valve mechanism shown in FIG. 5 of the second embodiment is substantially the same as that of the first embodiment, but the ratchet mechanism 56 rotates the lost motion lifter 42 not in the twisting direction P but in the return direction Q. This is different in that the return portion 43r for pressing the lost motion lifter 42 in the return direction Q is provided at the distal end portion 43b of the coil spring 43.

  The ratchet mechanism 56 allows the tip 43b to move relative to the lost motion lifter 42 in the twist direction P when the tip 43b of the coil spring 43 is slightly rotated in the twist direction P. When 43b slightly rotates in the return direction Q, the lost motion lifter 42 is engaged with the distal end portion 43b such that the lost motion lifter 42 cannot be relatively moved, so that the loft motion lifter 42 is moved back and forth as the coil spring 43 expands and contracts. It is a mechanism that rotates it.

  Specifically, the ratchet mechanism 56 includes a plurality of ratchet teeth 57 as in the first embodiment, but each ratchet tooth 57 has a distal end portion 43b of the coil spring 43 in the twisting direction on the return direction Q side. An inclined surface 59 that is allowed to move relative to P and is inclined at a relatively gentle angle with respect to the twisting direction P, and on the twisting direction P side, the tip end portion 43b cannot be moved relative to the return direction Q. The second embodiment is different from the first embodiment in that each has a locking surface 58 that is locked at a relatively steep angle with respect to the return direction Q.

  When the variable valve mechanism described above swings and opens and closes the valve 8, as in the first embodiment, (1) when the input unit 21 is stationary, (2) the opening direction of the input unit 21 The following description will be made separately for (3) when the input unit 21 is rotated in the closing direction C.

(1) When the input unit 21 is stationary Since the input unit 21 does not move in the opening and closing directions O and C, the lost motion lifter 42 and the coil spring 43 are stationary without moving as shown in FIG. At this time, the tip 43b of the coil spring 43 is positioned between one ratchet tooth 57i and one ratchet tooth 57j adjacent to the twisting direction P side.

(2) When the input unit 21 rotates in the opening direction O As the input unit 21 rotates in the opening direction O, the lost motion lifter 42 is pressed by the return arm 25 as shown in FIG. The coil spring 43 is compressed in the length directions V and W. At this time, the tip 43b of the coil spring 43 is slightly rotated in the twist direction P independently of the lost motion lifter 42 by sliding on the inclined surface 59 of the ratchet teeth 57j on the twist direction P side. Finally, as shown in FIG. 5 (c), the ratchet teeth 57j are crossed and moved between the ratchet teeth 57j and one ratchet tooth 57k adjacent to the twisting direction P side.

(3) When the input unit 21 is rotated in the closing direction C As shown in FIG. 5D, the input unit 21 is rotated in the closing direction C. As shown in FIG. The motion lifter 42 expands again. At this time, the distal end portion 43b of the coil spring 43 is slightly rotated in the return direction Q, and accordingly, the locking surface 58 of the ratchet teeth 57j that has been overcome in (2) is pressed in the return direction Q by the return portion 43r. As a result, the lost motion lifter 42 is slightly rotated in the return direction Q by one ratchet tooth 57.

  By repeating the operations (1), (2) and (3), the lost motion lifter 42 is gradually rotated in the return direction Q every time the coil spring 43 is extended.

  According to the second embodiment, the lost motion lifter 42 can be rotated in the return direction Q opposite to that in the first embodiment, and the same effect as in the first embodiment can be obtained by rotating in the opposite direction. Obtainable.

  In addition, this invention is not limited to the structure of the said Example 1, 2, It can also be changed and embodied in the range which does not deviate from the meaning of invention.

It is a perspective view which shows the variable valve mechanism of Example 1 of this invention. It is side sectional drawing which shows the variable valve mechanism of the Example. It is side sectional drawing which shows a motion of the lost motion mechanism of the Example. (A) is a perspective view showing a state when the lost motion lifter is rotated, (b) is a perspective view showing a state of wear of the lost motion lifter when the lost motion lifter is not rotated, (c) FIG. 5 is a perspective view showing a state of wear of the lost motion lifter when rotated. It is a side sectional view showing the movement of the lost motion mechanism of Example 2. (A) is a perspective view showing a valve operating mechanism of Conventional Example 1, (b) is a perspective view showing a state of wear of the valve lifter, and (c) is a perspective view showing a variable valve operating mechanism of Conventional Example 2, And (d) is a perspective view showing a state of wear of the lost motion lifter. (A) is a perspective view showing a state when the rotary cam of the valve mechanism of Conventional Example 1 is offset, (b) is a perspective view showing a state of wear of the valve lifter, and (c) is Conventional Example 2. The perspective view which shows the mode at the time of offsetting the lost motion mechanism of this variable valve mechanism, (d) is a perspective view which shows the mode of abrasion of the lost motion lifter.

Explanation of symbols

5 Internal combustion engine 8 Valve 9 Variable valve mechanism (valve mechanism)
10 Rotating cam 21 Input part (oscillating member)
26 Output section (oscillating member)
41 Lost motion mechanism 42 Lost motion lifter 43 Coil spring 46 Ratchet mechanism 56 Ratchet mechanism

Claims (1)

A swinging member interposed between a rotating cam and a valve so as to be swingable, and a lost motion mechanism that biases the swinging member to the rotating cam, and the swinging member rotates when the rotating cam rotates. In the valve operating mechanism of the internal combustion engine that swings and opens and closes the valve,
The lost motion mechanism is generated when a lost motion lifter that comes into contact with the swing member, a coil spring that presses the lost motion lifter against the swing member, and a circumferential twist and elastic extension that occur when the coil spring is elastically compressed. A valve operating system for an internal combustion engine, comprising: a ratchet mechanism that takes out one of rotational forces in both circumferential directions due to the return of the circumferential twist and rotates the lost motion lifter in one direction. mechanism.

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