JP2006118671A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device capable of reducing a frictional resistance at a meshing portion of a helical spline as much as possible and reducing a driving force required for the power transmission.
A maximum lift amount variable mechanism includes an intermediate drive mechanism, a support pipe, a control shaft, and a lift amount variable actuator. Each mediation drive mechanism 32 includes an input arm 36, a first output arm, and a second output arm 42. Each mediation drive mechanism 32 includes a power transmission slider gear 45 between the support pipe 33, the input arm 36, and both output arms. The helical spline 45c of the slider gear 45 is crowned on both the tooth tip surface 61 side and the tooth surface 60 side of the spline teeth.
[Selection] FIG.

Description

  The present invention relates to a power transmission device that converts a power transmission direction.

  2. Description of the Related Art Conventionally, a variable valve mechanism that makes the maximum lift amount of an intake valve or an exhaust valve variable according to the operating state of an internal combustion engine is known (see Patent Document 1). According to this variable valve mechanism, for example, in a low rotation and low load range, the maximum lift amount of the intake valve can be reduced and the intake air amount can be controlled to improve fuel efficiency. On the other hand, the output can be improved by increasing the maximum lift amount of the intake valve and improving the intake charging efficiency in the high rotation and high load range.

  By the way, such a variable valve mechanism includes a control shaft that is drivingly connected to an actuator, a slider gear that moves in the axial direction in conjunction with the control shaft, an input arm and an output arm that are engaged with the slider gear through a helical spline, and the like. I have. When power is applied to the control shaft by the actuator, the slider gear moves horizontally in the axial direction in conjunction with the control shaft, and the input arm and the output arm each rotate by a predetermined amount. Then, the relative phase difference between the nose of the output arm and the nose of the input arm is changed, and the maximum lift amount of the intake valve is adjusted. In such a variable valve mechanism, the lubricating oil is normally supplied to the meshing portion of the helical spline of the slider gear and the helical splines of the input arm and the output arm. With this lubricating oil, the frictional resistance when the helical splines slide between the slider gear and both arms is reduced, and the power is reduced to be applied to the control shaft.

Incidentally, as prior art documents according to the present invention, Patent Document 2 and Patent Document 3 describe a crown spline formed on a straight spline formed on a power transmission shaft. This aims at facilitating attachment / detachment with a member engaged with the power transmission shaft by performing crowning on the straight spline.
JP 2001-263015 A Japanese Patent Laid-Open No. 7-83242 JP 2001-287122 A

  By the way, when power is mutually converted in the horizontal direction and the rotational direction by such helical spline engagement, the tooth surfaces of each helical spline are always slid, so that the lubricity is maintained well in the sliding portion. Need to be. In this regard, in the variable valve mechanism, the slider gear and both arms have the helical spline teeth formed in a square shape. For this reason, it becomes difficult to sufficiently distribute the lubricating oil over the entire tooth surfaces of the helical spline of the slider gear and the helical splines of both arms, and the lubricating action of the lubricating oil is not sufficiently exhibited at the sliding portion. Sometimes. As a result, in order to move the slider gear by a predetermined amount in the axial direction, a large amount of power must be applied to the control shaft by the actuator, which may increase the output of the actuator and consequently increase the size of the device and increase the power consumption. was there.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the frictional resistance at the meshing portion of the helical spline as much as possible and to reduce the driving force required for the power transmission. Is to provide.

  In order to achieve the above object, according to the first aspect of the present invention, the first member that moves horizontally in the axial direction and the second member that rotates around the shaft are engaged by helical splines formed on both members. And a gap between the first helical spline of the first member and the second helical spline of the second member in the power transmission device that performs mutual conversion of power in the horizontal direction and the rotational direction through each movement of the members. The gist is that at least one end portion of the both end portions of the engaging portion is set larger than the other portions.

  According to this structure, the clearance gap between at least one edge part of the engaging part of the 1st helical spline of a 1st member and the 2nd helical spline of a 2nd member is made larger than another part. For this reason, when the first member is moved in the horizontal direction, the lubricating oil can be easily introduced into the meshing portion, that is, the engaging portion between the first helical spline and the second helical spline through the gap. Thereby, lubricating oil can be spread over the entire tooth surfaces of the first and second helical splines. Due to the lubricating action of the lubricating oil film formed in this way, slipping easily occurs when the tooth surfaces of the first and second helical splines slide, and the frictional resistance can be kept small. Therefore, when performing mutual conversion of power in the horizontal direction and the rotation direction, the force for moving each member in the horizontal direction and the rotation direction can be kept small.

  In addition, as a mode when the gap is increased at the end of the meshing portion of the helical spline as described above, it is desirable that the gap is gradually increased from the center to the end of the engaging portion. According to this configuration, when the first member is moved in the horizontal direction, the lubricating oil can be introduced into the engaging portions of the first and second helical splines from the ends thereof. Thereby, it becomes much easier to introduce the lubricating oil into the engaging portions of the first and second helical splines.

  According to a second aspect of the present invention, in the first aspect of the present invention, the gap between the first helical spline and the second helical spline may be different at both ends in the advancing / retreating direction when the first member moves horizontally. The gist is that it is set larger than the portion.

  According to this configuration, when the horizontally moving first member advances and retracts in the axial direction, the lubricating oil can be introduced from each end of the engaging portion between the first helical spline and the second helical spline each time. it can. For this reason, the introduction of the lubricating oil can be further promoted, and the frictional resistance when the tooth surfaces of both helical splines slide can be further reduced.

  In addition, as a structure which makes the clearance gap between a 1st helical spline and a 2nd helical spline larger than the other part in the at least one edge part of those engaging parts, as described in Claim 3, 1st helical It is possible to adopt a configuration in which one of the spline and the second helical spline is formed so that the tooth height decreases as it goes toward the end of the tooth line. Further, as another configuration, as described in claim 4, one of the first helical spline and the second helical spline is formed such that the tooth thickness decreases toward the end of the tooth trace. Can also be adopted. If this configuration is adopted, the lubricant is directly introduced into the tooth surfaces of the first and second helical splines, so that the frictional resistance when the tooth surfaces of both helical splines slide between each other is effectively reduced. Can be suppressed.

  According to a fifth aspect of the present invention, there is provided a slider gear that horizontally moves in the axial direction in conjunction with a control shaft that is drivingly connected to an actuator, and a helical spline that is engaged with the helical spline of the slider gear, And an input arm and an output arm that are interlocked with a cam formed on the engine camshaft. The input arm is configured to apply power to the control shaft and horizontally move the slider gear in the axial direction. The present invention is applied to a variable valve mechanism for an engine that changes the relative phase difference between the nose of the output arm and the nose of the output arm and changes the maximum lift amount of a valve that is opened and closed by the output arm.

  In this configuration, a helical spline is formed on each of the slider gear, the input arm, and the output arm, and the engaging portion of each helical spline is set to be larger than at the other end at least at one of its both ends. I have to. According to such a configuration, when the slider gear is moved horizontally in the axial direction, the lubricating oil is entrained and introduced into the engaging portion between the helical spline of the slider gear and the helical spline of the input arm and the output arm. it can. Thereby, introduction | transduction of lubricating oil can be accelerated | stimulated and the frictional resistance at the time of those helical splines sliding with respect to a slider gear, an input arm, and an output arm can be restrained small. For this reason, in the variable valve mechanism, when the slider gear is horizontally moved in the axial direction in order to change the maximum lift amount of the valve, it is possible to reduce the power applied to the control shaft by the actuator.

  In addition, when the slider gear is stopped at a predetermined position, the lubricating oil can be easily discharged from the engaging portion between the helical spline of the slider gear and the helical splines of the input arm and the output arm. It is also possible to promote film breakage of the lubricating oil film formed on the tooth surface. Therefore, the helical spline of the slider gear and the helical splines of the input arm and output arm are easily meshed with each other, and the frictional resistance at the contact surface where the tooth surfaces of both helical splines are in contact with each other can be increased. Therefore, when the slider gear is held at a predetermined position in order to maintain the maximum lift amount of the valve, the power applied to the control shaft by the actuator can be kept small.

Hereinafter, an embodiment in which a power transmission device of the present invention is applied to a variable valve mechanism mounted on an engine will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the engine 11 includes a cylinder head 12 and a cylinder block 14 having a plurality of cylinders 13. A piston 15 is accommodated in each cylinder 13 so as to be able to reciprocate. Each piston 15 is connected to the crankshaft 10 via a connecting rod.

  In each cylinder 13 of the engine 11, a combustion chamber 16 is defined by a cylinder block 14, a cylinder head 12, and a piston 15. The cylinder head 12 is provided with a pair of intake ports 17 and a pair of exhaust ports 18 communicating with each combustion chamber 16 for each cylinder 13. In order to open and close these intake / exhaust ports 17, 18, a pair of intake valves 21 and a pair of exhaust valves 22 are supported by the cylinder head 12 so as to reciprocate for each cylinder 13. The intake / exhaust valves 21 and 22 are always urged upward by the valve spring 23, that is, in the valve closing direction for closing the intake / exhaust ports 17 and 18.

  Above the intake valve 21, an intake camshaft 20 having one intake cam 24 for each cylinder 13 is rotatably supported by standing wall portions 25 and 26 formed in the cylinder head 12. Above the exhaust valve 22, an exhaust camshaft 27 having one exhaust cam for each cylinder 13 is rotatably supported by the cylinder head 12. The intake / exhaust camshafts 20 and 27 are drivingly connected to the crankshaft 10 via a timing chain 19 or the like. For this reason, the rotation of the crankshaft 10 is transmitted to the intake / exhaust camshafts 20 and 27 via the timing chain 19 and the like, whereby the camshafts 20 and 27 rotate. As the camshafts 20 and 27 rotate, the intake / exhaust valves 21 and 22 are reciprocated to open and close the intake / exhaust ports 17 and 18.

  Intake air is introduced into the combustion chamber 16 through the intake port 17 when the intake valve 21 is opened. Each cylinder 13 is provided with a fuel injection valve (not shown) for injecting fuel toward the combustion chamber 16 and a spark plug 28. In the combustion chamber 16, the fuel injected from the fuel injection valve and the intake air introduced through the intake port 17 are mixed to form an air-fuel mixture.

  As shown in FIG. 2, the engine 11 is provided with a maximum lift amount changing mechanism 31 that can continuously change the maximum lift amount and the operating angle of each intake valve 21. The maximum lift amount changing mechanism 31 includes an intermediate drive mechanism 32 provided for each cylinder 13, one support pipe 33, one control shaft 34, and one lift provided in common to each intermediate drive mechanism 32. A variable amount actuator 35 is provided.

  The support pipe 33 is disposed along the direction in which the cylinders 13 are arranged, and is fixed to the standing wall portion 25 by penetration. Hereinafter, the extending direction of the control shaft 34 is referred to as “axial direction”, and the direction thereof is indicated by an arrow F or an arrow R. The support pipe 33 is fixed so that it cannot move in the axial direction (direction indicated by the arrow F or R) and cannot rotate.

  A control shaft 34 is inserted and supported in the support pipe 33. The control shaft 34 is supported in the support pipe 33 so as to be horizontally movable in the axial direction. The lift amount variable actuator 35 includes a motor, a hydraulic cylinder, and the like, and a drive shaft (not shown) is connected to an end of the control shaft 34. As a result, the lift amount variable actuator 35 is driven to horizontally move the control shaft 34 in the axial direction, thereby adjusting the position in the axial direction.

  The intermediate drive mechanism 32 is disposed between the intake camshaft 20 and a pair of intake valves 21 corresponding thereto. As shown in FIG. 3, the mediation drive mechanism 32 includes an input arm 36 as a second member, and a first output arm 41 and a second output arm 42 that are also provided on both sides in the axial direction as second members. I have. The input arm 36 and the output arms 41 and 42 of the mediation drive mechanism 32 are disposed between the adjacent standing wall portions 25. The input arm 36 includes a pair of support pieces 37, and a roller 39 is supported at the tips of both support pieces 37 via a support shaft 38. Each of the first output arm 41 and the second output arm 42 includes a base circle portion 43 and a nose 44 having a substantially triangular shape, and a concave cam surface 44a is formed on the nose 44 in a curved manner.

  As shown in FIG. 1, each intermediary drive mechanism 32 is disposed at a position where the roller 39 of the input arm 36 and the intake camshaft 20 come into contact with each other. Thereby, the input arm 36 of each intermediary drive mechanism 32 swings up and down with the support pipe 33 as a fulcrum according to the cam shape of the intake cam 24. A spring 51 is disposed in a compressed state between the support piece 37 of the input arm 36 and the cylinder head 12. The roller 39 of the input arm 36 is always pressed against the intake cam 24 of the intake camshaft 20 by the urging force of the spring 51.

  A rocker arm 52 is disposed between the intake valve 21 and the output arms 41 and 42. Through the rocker arm 52, the swing of the output arms 41 and 42 with the support pipe 33 as a fulcrum is transmitted to the corresponding intake valve 21. In addition, each rocker arm 52 is disposed at a position where the base end portion 52 a is supported by the adjuster 54 and the tip end portion 52 b is in contact with the stem end 21 a of the intake valve 21. For this reason, the urging force of the valve spring 23 is applied to the distal end portion 52b of the rocker arm 52 via the intake valve 21, so that the roller 53 of the rocker arm 52 causes the base circular portion 43 or the nose of both the output arms 41 and 42 to move. 44 is in contact.

  As shown in FIGS. 4A, 4B and 5, in the intermediate drive mechanism 32, a slider as a first member is provided between the support pipe 33, the input arm 36, and the output arms 41, 42. A gear 45 is arranged. The slider gear 45 has a through hole 46 at the center thereof, and a support pipe 33 is slidably inserted into the through hole 46. For this reason, the slider gear 45 is supported on the support pipe 33 so as to be rotatable around the axis and horizontally movable in the axial direction.

  A helical spline 45a (first helical spline) for transmitting axially acting power to the input arm 36 when the slider gear 45 is moved horizontally is formed at a substantially central portion of the outer peripheral surface of the slider gear 45. Yes. The helical spline 45 a is formed so as to be inclined at a predetermined angle with respect to the central axis of the slider gear 45. On the other hand, a helical spline 36 a (second helical spline) is formed on the inner peripheral surface of the input arm 36 corresponding to the helical spline 45 a of the slider gear 45. The input arm 36 and the slider gear 45 are engaged when the helical spline 36a and the helical spline 45a mesh with each other.

  On the outer peripheral surface of the slider gear 45, a helical spline 45b (first helical spline) for transmitting axially acting power to the first output arm 41 and a second output arm 42 are provided at each axial end. And a helical spline 45c (first helical spline) for transmitting to each other. The helical splines 45b and 45c of the slider gear 45 are formed so that the inclination directions of the respective tooth traces and the inclination directions of the helical splines 45a described above are opposite to each other.

  On the other hand, a helical spline 41 b (second helical spline) is formed on the inner peripheral surface of the first output arm 41 corresponding to the helical spline 45 b of the slider gear 45. The first output arm 41 and the slider gear 45 are engaged when the helical spline 41b and the helical spline 45b are engaged with each other. A helical spline 42 c (second helical spline) is formed on the inner peripheral surface of the second output arm 42 corresponding to the helical spline 45 c of the slider gear 45. The second output arm 42 and the slider gear 45 are engaged when the helical spline 42c and the helical spline 45c are engaged with each other.

  As described above, when the slider gear 45, the input arm 36, and the output arms 41 and 42 are engaged through the corresponding helical splines, the slider gear 45 moves horizontally on the support pipe 33 in the axial direction. As a result, the rotational force in the opposite direction is transmitted to the input arm 36 and the output arms 41 and 42. With this rotational force, the input arm 36 and the output arms 41 and 42 are rotated in opposite directions, and the relative phase difference between the nose 44 of the input arm 36 and the nose 44 of the output arms 41 and 42 is changed. Will be.

  As shown in FIGS. 5 to 7, a circumferential groove 47 is formed in the slider gear 45 along the inner circumferential surface of the through hole 46. The slider gear 45 is formed with a pin insertion hole 47 a communicating with the circumferential groove 47. In the support pipe 33, a long hole 33 a extending in the axial direction is formed at a position corresponding to the intermediate drive mechanism 32. In the control shaft 34, a support hole 34a extending in a direction perpendicular to the axis is formed at a position corresponding to each intermediate drive mechanism 32.

  The locking pin 48 is locked at the base end portion in the support hole 34 a of the control shaft 34, and the distal end portion is inserted through a support hole 49 a formed through the center of the bush 49. The bush 49 has a rectangular shape, and its width in the axial direction is set substantially equal to the width of the circumferential groove 47. The bush 49 is inserted into a circumferential groove 47 formed on the inner peripheral surface of the slider gear 45 in a state where the locking pin 48 is inserted into the support hole 49 a of itself. Therefore, when the control shaft 34 is horizontally moved in the axial direction, the locking pin 48 moves in the long hole 33a of the support pipe 33, and accordingly, the slider gear 45 is horizontally moved in the axial direction. Further, since the bush 49 is slidably supported along the circumferential groove 47, the slider gear 45 is rotatable about the axis of the support pipe 33.

  A lubricating oil passage 56 is formed by a gap between the inner wall surface of the support pipe 33 and the control shaft 34. A part of the lubricating oil discharged from the engine oil pump is supplied to the lubricating oil passage 56. Then, the lubricating oil supplied to the lubricating oil passage 56 passes through an oil supply port (not shown), and the helical splines 45a, 45b, and 45c of the slider gear 45, the helical spline 36a of the input arm 36, and the helical splines of both the output arms 41 and 42. It is supplied to the meshing part with 41b, 42c, that is, the engaging part.

  Next, the helical spline 45c of the slider gear 45 will be described with reference to FIGS. FIG. 8 is an enlarged perspective view of the helical spline 45 c of the slider gear 45. 9A is a cross-sectional view taken along the line AA in FIG. 8, and FIG. 9B is a cross-sectional view taken along the line BB in FIG. Here, since the helical splines 45a and 45b of the slider gear 45 have the same configuration as the helical spline 45c, description thereof will be omitted.

  As shown in FIG. 8, the helical spline 45 c of the slider gear 45 is crowned on the tooth tip surface 61 side and the tooth surface 60 side of the spline teeth 58. That is, as shown in FIGS. 9 (a) and 9 (b), the spline teeth 58 have a smooth convex shape on the entire tooth surface 60, and the tooth thickness w is the center of the tooth line of the helical spline 45c. It is formed so as to become gradually smaller as it goes to both ends of the tooth line. In addition, the spline teeth 58 have a smooth convex surface shape as a whole of the tooth tip surface 61, and the tooth height h is the largest at the center of the tooth line of the helical spline 45c and faces both ends of the tooth line. It is formed so as to gradually become smaller.

  Next, gaps d1 and d2 formed between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 will be described with reference to FIG. 10A shows a side view when the spline teeth 58 are viewed from the tooth surface 60 side, and FIG. 10B is a view when the spline teeth 58 are viewed from the groove bottom 59 (see FIG. 8) side. A perspective view is shown.

  As shown in FIG. 10A, the gap d1 between the tooth tip surface 61 of the helical spline 45c and the groove bottom 64 of the helical spline 42c is the smallest at the center of the tooth line of the helical spline 45c, and both end portions of the tooth line. It gradually increases as you go to. Also, as shown in FIG. 10B, the gap d2 between the tooth surface 60 of the helical spline 45c and the tooth surface 66 of the helical spline 42c is the smallest at the center of the tooth line of the helical spline 45c, and both ends of the tooth line are the same. It gradually grows as it goes to the club. That is, the gaps d1 and d2 between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 are set larger than the other portions at both ends of the engaging portions of the helical splines 45c and 42c. Yes. That is, the gaps d1 and d2 are located at both ends of the engaging portion of the helical splines 45c and 42c at the side of the slider gear 45 in the forward / backward direction (F direction and R direction shown in FIGS. 10A and 10B). It is set larger than the other parts.

  The relative position of the nose 44 of the first and second output arms 41 and 42 with respect to the roller 39 of the input arm 36 is changed by adjusting the axial position of the control shaft 34 by the lift amount variable actuator 35. Along with this change, the maximum lift amount and operating angle of the intake valve 21 change continuously. Since the series of operations for opening and closing the intake valve 21 is the same for the first and second output arms 41 and 42, only the opening and closing operation of the intake valve 21 by the second output arm 42 is shown in FIGS. This will be described with reference to FIG.

  FIG. 11 shows the mediation when the control shaft 34 is moved in the direction indicated by the arrow R in FIG. 2 by the lift amount variable actuator 35 to minimize the relative phase difference between the input arm 36 and the second output arm 42. The drive mechanism 32 is shown. This figure shows a state where the base circle portion 24a of the intake cam 24 and the roller 39 of the input arm 36 are in contact with each other. In this state, the second output arm 42 is in contact with the roller 53 of the rocker arm 52 closer to the base circle 43 than the base end of the nose 44. For this reason, the cam surface 44a does not push down the roller 53 of the rocker arm 52, and the pressing operation of the stem end 21a by the distal end portion 52b of the rocker arm 52 is also stopped.

  Even if the second output arm 42 swings from this state, the roller 53 of the rocker arm 52 continues to contact the base circle 43 without contacting the cam surface 44 a of the nose 44. That is, even if the nose 24b of the intake camshaft 20 pushes down the roller 39 of the input arm 36 to the maximum, the cam surface 44a does not push down the roller 53 of the rocker arm 52. For this reason, the rocker arm 52 does not swing, the amount by which the stem end 21a is pushed down by the tip 52b of the rocker arm 52 becomes zero, and the closed state of the intake valve 21 is maintained.

  FIG. 12 shows the mediation drive mechanism 32 when the control shaft 34 is moved in the direction indicated by the arrow F in FIG. 2 to gradually increase the relative phase difference between the input arm 36 and the second output arm 42. . At this time, axial power is applied to the slider gear 45 by the lift variable actuator 35 via the control shaft 34. The slider gear 45 horizontally moves in the axial direction while sliding the tooth surface 60 of the helical spline 45 c and the tooth surface 66 of the helical spline 42 c of the second output arm 42. Along with this, the contact position between the second output arm 42 and the roller 53 of the rocker arm 52 gradually approaches the tip side of the nose 44 from the base circle 43 side.

  Here, as the slider gear 45 is moved back and forth in the axial direction, between the helical spline 45c and the helical spline 42c of the second output arm 42, each end of the engaging portion of both the helical splines 45c and 42c. The lubricating oil Q is introduced in such a manner as to be caught from the part. As a result, a lubricating oil film is rapidly formed on the entire tooth surfaces 60 and 66 of the helical splines 45c and 42c. The lubricating action of the lubricating oil film suppresses the frictional resistance when the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 slide. The helical splines 45a and 45b of the slider gear 45 also have a small frictional resistance when sliding with the helical splines 36a and 41b of the input arm 36 and the first output arm 41, similarly to the helical spline 45c.

  FIG. 13 shows the mediation when the control shaft 34 is moved in the direction indicated by the arrow F in FIG. 2 by the lift amount variable actuator 35 to maximize the relative phase difference between the input arm 36 and the second output arm 42. The drive mechanism 32 is shown. As shown in the figure, the roller 39 of the input arm 36 is pushed down by the nose 24 b of the intake cam 24. At this time, the input arm 36 swings downward and the second output arm 42 swings downward. By this swinging, the cam surface 44 a of the nose 44 comes into contact with the roller 53 of the rocker arm 52. Then, the roller 53 is pushed down, and the rocker arm 52 swings downward with the base end portion 52a as a fulcrum. Then, the intake valve 21 greatly opens (opens) the intake port 17 by the tip end 52b of the rocker arm 52 greatly pushing down the stem end 21a.

  Here, in order to maintain the relative phase difference between the input arm 36 and the second output arm 42, the slider gear 45 is stopped at a predetermined position in the axial direction. At this time, the axial power by the variable lift amount actuator 35 is continuously applied to the slider gear 45 via the control shaft 34.

  Thus, in a state where the relative phase difference between the input arm 36 and the second output arm 42 is maintained at a predetermined phase difference, the engagement portion between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 is maintained. Lubricating oil Q is quickly discharged from both ends. Thereby, the film breakage of the lubricating oil film formed on the entire tooth surfaces 60 and 66 of the helical splines 45c and 42c is promoted. Since the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 are easily meshed with each other, it is possible to increase the frictional resistance at the contact surfaces of the helical splines 45c and 42c.

  In this state, the second output arm 42 has a repulsive force caused by pushing up the intake valve 21 in a direction (P direction shown in FIG. 13) that reduces the relative phase difference with the input arm 36 via the rocker arm 52. It has been added. In this case, since the frictional resistance at the contact surfaces of both the helical splines 45c and 42c is kept large, the power applied to the slider gear 45 by the variable lift amount actuator 35 can be reduced accordingly. The helical splines 45a and 45b of the slider gear 45 also maintain a large frictional resistance at the contact surfaces of the input arm 36 and the first output arm 41 with the helical splines 36a and 41b, similarly to the helical spline 45c. Yes.

According to the variable valve mechanism of the above embodiment, the following effects can be obtained.
(1) The gaps d1 and d2 between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 are set larger than the other portions at both ends of the engaging portions of both the helical splines 45c and 42c. ing. According to this configuration, as the slider gear 45 is advanced and retracted in the axial direction, the lubricating oil Q can be easily introduced from the end portions of the engaging portions of the helical splines 45c and 42c. Thereby, the lubricating oil Q can be spread over the entire tooth surfaces 60 and 66 of the helical splines 45c and 42c, and the lubricating oil film can be easily formed. By the lubricating action of the lubricating oil film thus formed, the frictional resistance when the helical splines 45c and 42c slide with respect to the slider gear 45 and the second output arm 42 can be kept small. Therefore, when the slider gear 45 is horizontally moved in the axial direction in order to change the maximum lift amount of the intake valve 21, the power applied to the control shaft 34 by the lift amount variable actuator 35 can be kept small.

  Further, when the slider gear 45 is stopped at a predetermined position in the axial direction in order to maintain the maximum lift amount of the intake valve 21, the engagement portion between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 is maintained. Lubricating oil Q can be easily discharged from both ends. In this case, the film breakage of the lubricating oil film formed on the entire tooth surfaces 60 and 66 of the helical splines 45c and 42c can be promoted. As a result, the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 are easily meshed with each other, so that the frictional resistance between the helical splines 45c and 42c can be increased. Accordingly, even if the power applied to the control shaft 34 by the lift amount variable actuator 35 is small, the slider gear 45 can be easily held at a predetermined position in the axial direction.

  Therefore, by applying the present invention to the maximum lift amount changing mechanism 31 constituting the variable valve mechanism, it is possible to suppress an increase in the output of the lift amount variable actuator 35 constituting the mechanism 31, and to increase the size of the apparatus. It is possible to prevent the increase in power consumption and power consumption.

  (3) The helical spline 45c of the slider gear 45 is crowned on both the tooth tip surface 61 side and the tooth surface 60 side of the spline teeth 58, respectively. As a result, the gaps d1 and d2 between the helical splines 45c and 42c are set larger than the other portions at both ends of the engaging portion between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42. It becomes possible to do. Further, in the helical spline 45c of the slider gear 45 subjected to such crowning processing, the entire tooth surface 60 of the spline tooth 58 has a smooth convex shape, and the entire tooth tip surface 61 has a smooth convex shape. ing. Thereby, the frictional resistance when the tooth surface 60 of the helical spline 45c of the slider gear 45 and the tooth surface 66 of the helical spline 42c of the second output arm 42 slide can be further reduced. Further, the contact between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 can be kept good, and wear and damage of the spline teeth 58 due to stress concentration can be suppressed as much as possible.

In addition, you may change the said embodiment as follows.
In the present embodiment, not only the spline teeth 58 of the helical splines 45a, 45b, 45c of the slider gear 45 but also at least one of the helical splines 36a, 41b, 42c of the input arm 36 and the first and second output arms 41, 42 One spline tooth 58 may be crowned.

  Further, the crowning process applied to the spline teeth 58 of the helical splines 45a, 45b, 45c of the slider gear 45 is omitted, and the helical splines 36a, 41b, 42c of the input arm 36 and the first and second output arms 41, 42 are omitted. The at least one spline tooth 58 may be crowned. Further, at least one spline tooth 58 of the helical splines 45a, 45b, 45c of the slider gear 45 may be subjected to crowning.

  In the present embodiment, the helical spline 45c of the slider gear 45 is crowned on both the tooth tip surface 61 side and the tooth surface 60 side of the spline teeth 58, but the tooth tip surface 61 side and the tooth surface Only one of the 60 sides may be subjected to crowning. Normally, the processing of the spline teeth 58 is easier than the processing of the tooth thickness. Therefore, if a configuration in which crowning is applied only to the tooth tip surface 61 side, the processing time and the processing cost are reduced. Etc. can be achieved. Further, in the case where the crowning process is applied only to the tooth surface 60 side of the spline teeth 58, both the helical splines 45c, c are formed through the gap d2 between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42. The lubricating oil Q is directly introduced into the tooth surfaces 60 and 66 of 42c. Therefore, even with such a configuration, it is possible to effectively reduce the frictional resistance of the slider gear 45 and the second output arm 42 when the helical splines 45c and 42c slide.

  In the present embodiment, the helical spline 45c of the slider gear 45 is formed so that the tooth height h of the spline teeth 58 becomes smaller toward the both ends from the center of the tooth trace. The tooth height h may be reduced from the center to the end, and the tooth height h may be constant from the center to the other end. Similarly, the helical spline 45c of the slider gear 45 is formed so that the tooth thickness w of the spline tooth 58 becomes smaller toward the both ends of the tooth stripe, but the tooth thickness w from the center of the tooth stripe to one end thereof. The tooth thickness w may be constant from the center to the other end. In these cases, the gaps d1 and d2 between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 are larger than the other portions only at one end of the engaging portion of both the helical splines 45c and 42c. Will be set.

  In the present embodiment, the helical spline 45c has a smooth convex surface shape on the entire tooth surface 60 of the spline tooth 58, but only the both end portions or one end portion of the helical spline 45c has a smooth convex surface shape. It may be. Similarly, with respect to the tooth tip surface 61 of the spline tooth 58, only the both ends or one end of the helical spline 45c may have a smooth convex shape.

  In the present embodiment, the helical spline 45c has a smooth convex shape on the entire tooth surface 60 of the spline tooth 58, but a flat slope (taper) is provided at the end of the tooth line of the helical spline 45c. Thus, the spline teeth 58 may be trapezoidal. Further, by forming the end of the helical spline 45c to have a stepped shape or an R shape, the gaps d1 and d2 between the helical spline 45c of the slider gear 45 and the helical spline 42c of the second output arm 42 are the same. You may make it become larger than an other part in an edge part.

  -In this embodiment, although the power transmission device was applied to the maximum lift amount changing mechanism 31 which makes the maximum lift amount of the valve of the vehicle-mounted engine variable, the mutual conversion of power in horizontal movement and rotational movement through a helical spline As long as it performs, it may be applied to any one. Specific examples include a valve timing mechanism that makes the opening / closing timing of a valve of an in-vehicle engine variable, a vehicle power transmission system component such as a transmission, a clutch device, and pedals, and various machine tools such as a lathe. .

  In the present embodiment, in the maximum lift amount changing mechanism 31, the lift amount variable actuator 35 is drivingly connected to the horizontally moving control shaft 34. However, depending on the application example of the power transmission device, the rotating member that rotates and moves the actuator May be driven and connected.

  -In this embodiment, you may employ | adopt arbitrary drive sources, such as a rotation motor, a linear motor, a hydraulic cylinder, an air cylinder, as an actuator.

The fragmentary sectional view of the engine to which the variable valve mechanism in this embodiment was applied. The schematic plan view which shows the arrangement | positioning relationship of the cam shaft and variable valve mechanism in a cylinder head. The perspective view of a mediation drive mechanism. (A) is a partially broken perspective view when the mediation drive mechanism is viewed from the front side, and (b) is a partially broken perspective view when the mediation drive mechanism is viewed from the back side. The partial interruption | blocking perspective view which shows the internal structure of a mediation drive mechanism. FIG. 3 is a vertical cut perspective view of a slider gear. The exploded perspective view of the principal part of a support pipe and a control shaft. The expansion perspective view of the helical spline formed in the slider gear. (A) is AA sectional drawing of FIG. 8, (b) is BB sectional drawing of FIG. (A), (b) is explanatory drawing which shows the clearance gap between the helical spline of a slider gear, and the helical spline of a 2nd output arm. Explanatory drawing which shows operation | movement of a variable valve mechanism. Explanatory drawing which shows operation | movement of a variable valve mechanism. Explanatory drawing which shows operation | movement of a variable valve mechanism.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 20, 27 ... Camshaft, 21 ... Intake valve, 22 ... Exhaust valve, 34 ... Control shaft, 35 ... Lift amount variable actuator, 36 ... Input arm, 36a ... Helical spline, 41 ... First output arm, 42 ... second output arm, 41b ... helical spline, 42c ... helical spline, 44 ... nose, 45 ... slider gear, 45a ... helical spline, 45b ... helical spline, 45c ... helical spline.

Claims (5)

A first member that moves horizontally in the axial direction and a second member that rotates around the shaft are engaged by helical splines formed on both members, and the mutual movement of power in the horizontal direction and the rotating direction is achieved through the movement of these members. In the power transmission device that performs the conversion, the gap between the first helical spline of the first member and the second helical spline of the second member is set to be at least one of the both end portions of the engaging portion from the other portion. The power transmission device is characterized by being set to a large value. The power transmission device according to claim 1,
The power transmission device, wherein a gap between the first helical spline and the second helical spline is set larger than other portions at both end portions in the advancing and retreating direction when the first member moves horizontally. The power transmission device according to claim 1 or 2,
One of said 1st helical spline and said 2nd helical spline is formed so that tooth height may become small as it goes to the edge part of a tooth trace. The power transmission device characterized by the above-mentioned. In the power transmission device according to any one of claims 1 to 3,
One of said 1st helical spline and said 2nd helical spline is formed so that tooth thickness may become small as it goes to the edge part of a tooth trace. The power transmission device characterized by the above-mentioned. In the power transmission device according to any one of claims 1 to 4,
A slider gear that moves horizontally in the axial direction in conjunction with a control shaft that is drivingly connected to the actuator;
An input arm and an output arm that have a helical spline engaged with the helical spline of the slider gear, rotate about an axis, and interlock with a cam formed on the camshaft of the engine;
By applying power to the control shaft and horizontally moving the slider gear in the axial direction, the relative phase difference between the nose of the input arm and the nose of the output arm is changed, and the valve opened and closed by the output arm is changed. A power transmission device that is applied to an engine variable valve mechanism that changes a maximum lift amount.

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