JP2017025748A - Variable valve train - Google Patents

Abstract

When assembling an input arm, an output arm, and a slider gear, if the input arm and the output arm are mistakenly assembled, it is easy to notice the wrong assembly. In a variable valve mechanism configured to change a relative phase difference between a roller 41a of an input arm 41 and a nose 42a of an output arm 42 by movement of the slider gear 43 in the axial direction, the input side of the slider gear 43 is provided. The number of teeth of the helical spline 43a is the same as the number of teeth of the output side helical spline 43b, and the module of the output side helical spline 43b is made smaller than the module of the input side helical spline 43a. With such a configuration, when the slider gear 43 and the input arm 41 and the output arm 42 are assembled, if the phases of the input arm 41 and the output arm 42 are wrongly assembled, it is easy to notice the wrong assembly. [Selection] Figure 3

Description

  The present invention relates to a variable valve mechanism that continuously changes the valve characteristics of an intake valve and an exhaust valve of an internal combustion engine.

  2. Description of the Related Art A variable valve mechanism that makes a valve lift amount (maximum lift amount) of an engine valve (intake valve / exhaust valve) variable in accordance with an operating state of an internal combustion engine (hereinafter also referred to as an engine) is known. As an example of a variable valve mechanism, a cylindrical rocker shaft (support pipe) fixed to the engine, a control shaft disposed in an axially movable state within the rocker shaft, and a rocker shaft are provided. There is also a variable valve lift mechanism that continuously changes the working angle and valve lift amount of the engine valve (see, for example, Patent Document 1).

  In such a variable valve mechanism, a variable valve lift mechanism is provided for each cylinder of the engine, and a slider gear that can move in the axial direction in conjunction with a control shaft, and an input arm that is driven by a camshaft cam. And an output arm for lifting the engine valve. The slider gear is formed with an input-side helical spline that meshes with the input arm and an output-side helical spline that meshes with the output arm. Also, a helical spline that meshes with the input side helical spline of the slider gear is formed on the inner peripheral surface of the input arm, and similarly, a helical spline that meshes with the output side helical spline of the slider gear is formed on the inner peripheral surface of the output arm. ing.

  In the variable valve mechanism having the above configuration, the input arm is swung by the camshaft of the engine. The swing of the input arm is transmitted to the output arm via the slider gear, so that the output arm swings, and the engine valve is pushed down against the valve spring by the swing of the output arm. When the control shaft is moved in the axial direction, the slider gear is rotated in conjunction with the movement, and is moved in the axial direction. As a result, the relative phase difference between the input arm and the output arm is changed by the helical spline, and accordingly, the operating angle of the engine valve and the valve lift amount are changed.

JP 2006-118671 A

  In the variable valve mechanism described above, when the input side helical spline is arranged at the center of the slider gear and the output side helical splines are arranged on both sides of the input side helical spline, respectively (for example, applicable to a 4-valve engine) There is a variable valve mechanism). In the variable valve mechanism having such a structure, in order to enable the slider gear to be assembled to the input arm, the number of teeth on the output side helical spline is smaller than that on the input side helical spline, and the outer diameter of the output side helical spline is input. It is smaller than the side helical spline.

  Thus, in the structure where the number of teeth on the input side helical spline and the number of teeth on the output side helical spline of the slider gear are different, when the input arm, the output arm and the slider gear are assembled, the input arm and the output arm are mistakenly assembled. When one tooth is deviated in the direction (one direction of small working angle or large working angle), the phases of the input arm and the output arm are shifted. However, the deviation of the arm phase is small (the difference is equivalent to the number of teeth difference between the number of teeth on the input-side helical spline and the number of teeth on the output-side helical spline). You may not notice the mistake.

  The present invention has been made in consideration of such circumstances, and when the input arm and the output arm and the slider gear are assembled, if the input arm and the output arm are mistakenly assembled, it is easy to notice the assembly error. An object of the present invention is to provide a variable valve mechanism.

  The present invention includes an axially movable control shaft, a slider gear that is movable in the axial direction in conjunction with the control shaft, and has an input side helical spline and an output side helical spline formed on the outer periphery, and a roller An input arm formed with a helical spline that meshes with the input side helical spline of the slider gear on the inner periphery, and an output arm with a nose and formed with a helical spline that meshes with the output side helical spline of the slider gear; In the variable valve mechanism configured to change the relative phase difference between the roller of the input arm and the nose of the output arm according to the movement of the slider gear in the axial direction, the input side helical of the slider gear Number of teeth on the spline and teeth on the output helical spline DOO are the same, and the module of the output-side helical spline is being smaller than the module of the input-side helical spline.

  According to the present invention, the number of teeth on the input-side helical spline of the slider gear is the same as the number of teeth on the output-side helical spline, and the output-side helical spline module is made smaller than the input-side helical spline. Is made smaller than the outer diameter of the input-side helical spline.

  By making the number of teeth of the input side helical spline of the slider gear the same as the number of teeth of the output side helical spline, when the input arm, the output arm and the slider gear are assembled, the input arm and the output arm are in the same direction ( When one tooth shifts in one direction (small direction of working angle or large direction of working angle), the arm phases of the input arm and the output arm do not relatively shift.

  When the output arm deviates by one tooth from the input arm to the small working angle side (small working angle direction) or large working angle side (large working angle direction), the input arm is out of phase with the output arm (angular displacement). ) Is a large angle (360 ° / number of teeth) corresponding to one tooth of the spline teeth, so that it is possible to notice an assembly error.

  Specifically, when the output arm is shifted by one tooth to the small operating angle side with respect to the input arm, the operating angle of the variable valve mechanism becomes small and misfiring is likely to occur. be able to. Also, if the output arm deviates by one tooth from the input arm to the larger operating angle side, the operating angle of the variable valve mechanism increases and the piston and engine valve interfere with each other (a piston stamp is generated). You can notice the assembly error from the hard abnormality.

  Here, in the present invention, since the module of the output side helical spline of the slider gear is made small, when the piston stamp is generated due to the wrong assembly to the large working angle side, the output side helical spline is generated by the load received from the piston. Tends to shear. If the output-side helical spline is deformed, the engine torque is normal because the relative phase difference between the roller of the input arm and the nose of the output arm is in a low lift state even if the slider gear is moved to a position where the bubble lift amount is increased. Lower than when assembled. By this torque reduction, the user can know the engine abnormality.

  In the present invention, the number of teeth of the input-side helical spline and the output-side helical spline of the slider gear is as described above when the output arm deviates by one tooth from the input arm to the large working angle side or the small working angle side. It is preferable to set the number of teeth (for example, 24 teeth) or less where stamping or misfire occurs.

  According to the variable valve mechanism of the present invention, since the number of teeth of the input side helical spline of the slider gear and the number of teeth of the output side helical spline are the same, when the input arm, the output arm and the slider gear are assembled, the input arm If you make a mistake in the assembly of the output arm, you can notice the wrong assembly.

It is a schematic block diagram which shows an example of the engine by which a variable valve mechanism is mounted. It is a perspective view which shows the principal part structure of a variable valve mechanism. It is a disassembled perspective view which shows the principal part structure of a variable valve mechanism. It is operation | movement explanatory drawing of a variable valve mechanism. It is operation | movement explanatory drawing of a variable valve mechanism. It is a figure which shows the working angle when the output arm is shifted by one tooth to the small working angle side with respect to the input arm, and the working angle when the output arm is shifted by one tooth to the large working angle side with respect to the input arm .

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

-Engine-
First, an engine (internal combustion engine) equipped with a variable valve mechanism will be described with reference to FIG.

  The engine 1 in this example includes a cylinder block 10 and a cylinder head 11 provided on the upper portion of the cylinder block 10. The engine 1 is, for example, an in-line 4-cylinder gasoline engine (4-valve engine). FIG. 1 shows only one of the four cylinders.

  The cylinder block 10 is formed with a cylinder bore 10a. A piston 12 is accommodated in the cylinder bore 10a so as to be capable of reciprocating. The piston 12 is connected to a crankshaft (not shown) via a connecting rod (not shown), and the reciprocating motion of the piston 12 is converted into rotation of the crankshaft by the connecting rod.

  A combustion chamber 1a is formed between the piston 12 and the cylinder head 11 in the cylinder bore 10a. The cylinder head 11 is provided with a pair of intake ports 13 and exhaust ports 14 communicating with each combustion chamber 1a for each cylinder. A spark plug (not shown) is disposed on the cylinder head 11 so as to face the combustion chamber 1a.

  Further, the cylinder head 11 is provided with two intake valves 21 for opening and closing each intake port 13 and two exhaust valves 22 for opening and closing the exhaust port 14. Each intake valve 21 is provided with a valve spring 25, and each intake valve 21 is urged in a direction to close the intake port 13 by the elastic force of the valve spring 25. Similarly, each exhaust valve 22 is provided with a valve spring 25.

  Above the intake valve 21, an intake camshaft 23 having an intake cam 23a is disposed. An exhaust camshaft 24 having an exhaust cam 24a is disposed above the exhaust valve 22. The intake camshaft 23 and the exhaust camshaft 24 are connected to a crankshaft via a timing chain (not shown) or the like, and the rotation of the crankshaft is transmitted to the intake camshaft 23 and the exhaust camshaft 24. With each rotation of the intake camshaft 23 and the exhaust camshaft 24, the intake valve 21 and the exhaust valve 22 reciprocate.

  A rocker arm 26 having a roller 26a is swingably disposed between the upper end portion of the intake valve 21 and the intake cam 23a and between the upper end portion of the exhaust valve 22 and the exhaust cam 24a. Further, hydraulic lash adjusters 27 are disposed in the vicinity of the upper ends of the intake valve 21 and the exhaust valve 22, respectively. A compression reaction force of the valve spring 25 and a push-up force of the lash adjuster 27 are transmitted to the rocker arm 26, and the roller 26a of the rocker arm 26 is biased substantially upward by these transmission forces. The roller 26a having such a structure directly contacts the exhaust cam 24a and indirectly contacts the intake cam 23a via a variable valve mechanism 30 described later.

  In the engine 1 described above, an intake passage is connected to the intake port 13, and air outside the engine 1 is taken into the combustion chamber 1 a through the intake passage and the intake port 13. An injector (not shown) for fuel injection is disposed in the intake passage. Fuel of a predetermined pressure is supplied from the fuel tank to the injector by a fuel pump, and the fuel is injected into the intake passage. This injected fuel is mixed with intake air to form an air-fuel mixture, and is introduced into the combustion chamber 1 a of the engine 1 through the intake port 13. The air-fuel mixture (fuel + air) introduced into the combustion chamber 1a is ignited by the spark plug 3 and burns and explodes. The piston 12 reciprocates due to combustion / explosion of the air-fuel mixture in the combustion chamber 1a, and the crankshaft rotates.

-Variable valve mechanism-
In the engine 1 as described above, the variable valve mechanism 30 is provided in the vicinity of the intake camshaft 23. Hereinafter, the configuration of the variable valve mechanism 30 will be described with reference to FIGS.

  The variable valve mechanism 30 is a mechanism for continuously changing the operating angle and valve lift amount (maximum lift amount) of the intake valve 21, and is provided between the intake cam 23 a of the intake cam shaft 23 and the rocker arm 26. It is arranged.

  The variable valve mechanism 30 includes a rocker shaft 31, a control shaft 32, an actuator 33, and a variable valve lift mechanism 40.

  The rocker shaft 31 is a cylindrical member extending along a direction parallel to the intake camshaft 23 (cylinder arrangement direction, F / R direction indicated by arrows in FIG. 2), and a plurality of supports provided on the cylinder head 11. It is attached to a wall (not shown) in a state where movement in the axial direction and the circumferential direction is restricted. The direction in which the rocker shaft 31 extends is referred to as the “axial direction”.

  The control shaft 32 is inserted into the rocker shaft 31 so as to be movable in the axial direction. The control shaft 32 is moved forward and backward in the axial direction (F direction or R direction shown in FIG. 2) by the actuator 33.

  The variable valve lift mechanism 40 is mounted on the rocker shaft 31 so as to correspond to each cylinder. The variable valve lift mechanism 40 includes an input arm 41, two output arms 42 and 42, and a slider gear 43.

  The input arm 41 is a cylindrical member and includes a roller 41 a that is in sliding contact with the intake cam 23 a of the intake cam shaft 23. A helical spline 41 b that meshes with an input-side helical spline 43 a of a slider gear 43 described later is formed on the inner peripheral surface of the input arm 41.

  Output arms 42 and 42 are disposed on both sides of the input arm 41 in the axial direction. Each output arm 42 is a cylindrical member and has a nose 42 a that presses the rocker arm 26. A helical spline 42b that meshes with an output-side helical spline 43b of a slider gear 43, which will be described later, is formed on the inner peripheral surface of each output arm 42.

  The slider gear 43 is a substantially cylindrical member, and is externally mounted on the rocker shaft 31 so as to be movable in the axial direction. The slider gear 43 is engaged with the control shaft 32 via a pin (not shown). When the control shaft 32 moves in the axial direction, the slider gear 43 moves in the axial direction in conjunction with the movement of the control shaft 32. To move to. The slider gear 43 is provided so as to be rotatable with respect to the control shaft 32.

  An input-side helical spline 43 a that engages with the helical spline 41 b of the input arm 41 is machined in the central portion of the slider gear 43 in the axial direction. At both ends in the axial direction of the slider gear 43, output-side helical splines 43b that are engaged with the helical splines 42b of the output arm 42 are respectively machined. The output side helical spline 43b has a smaller outer diameter than the input side helical spline 43a. Further, the input side helical spline 43a and the output side helical spline 43b are processed so that the directions of twisting of teeth are opposite to each other.

  As shown in FIG. 1, the roller 41 a of the input arm 41 is pressed against the intake cam 23 a of the intake cam shaft 23 by the lost motion spring 50. Further, the rollers 26a of the rocker arm 26 of each intake valve 21 are pressed against the two output arms 42, 42 from the base circle to the nose 42a by the reaction force of the valve spring 25 of the intake valve 21, respectively. ing. Thus, when the input arm 41 is swung by the rotation of the intake camshaft 23, the rocker arm 26 is operated by the output arm 42 that swings integrally therewith, and the intake valve 21 is lifted.

  Furthermore, when the control shaft 32 is displaced in the axial direction, the slider gear 43 is displaced in the axial direction on the rocker shaft 31 in conjunction with the displacement. The displacement of the slider gear 43 in the axial direction is caused by the engagement of the two helical splines 43a and 43b of the slider gear 43 with the helical spline 41b of the input arm 41 and the helical spline 42b of the output arm 42. Converted to circumferential displacement.

  That is, the axial displacement of the control shaft 32 is converted into the circumferential displacement of the input arm 41 and the output arm 42 by the slider gear 43 in the variable valve lift mechanism 40 so that they are rotated in opposite directions. Become. As a result, the relative phase difference between the roller 41a of the input arm 41 and the nose 42a of the output arm 42 changes, and the valve lift amount and operating angle of the intake valve 21 are continuously changed as described below.

  For example, in the state where the control shaft 32 has moved to the maximum in the direction F shown in FIG. 2, the rollers 41a of the input arm 41 and the noses 42a of the output arm 42 are shown in FIGS. 4 (A) and 4 (B). The angle (relative phase difference) becomes maximum. As a result, as shown in FIG. 4B, the amount of displacement of the rocker arm 26 is maximized when the roller 41a of the input arm 41 is pushed down by the intake cam 23a of the intake cam shaft 23, and the intake valve 21 is at the maximum. The valve lift amount and the operating angle are operated.

  When the control shaft 32 moves in the R direction shown in FIG. 2 from this state, the angle between the roller 41a of the input arm 41 and the nose 42a of the output arm 42 gradually decreases. When the angle is minimized as shown in FIGS. 5A and 5B, the roller 41a of the input arm 41 is pushed down by the intake cam 23a of the intake camshaft 23 as shown in FIG. 5B. Even in this state, the displacement amount of the rocker arm 26 becomes very small, and the intake valve 21 operates with the minimum valve lift amount and operating angle.

-Helical spline specifications-
First, as described above, in order to allow the slider gear to be assembled to the input arm, in the prior art, the number of teeth on the output-side helical spline of the slider gear is smaller than that on the input-side helical spline, and the outer diameter of the output-side helical spline is reduced. Is made smaller.

  Specifically, in the prior art, the number of teeth on the input side helical spline (the number of teeth on the helical arm of the input arm) is 26 (module: 1.00, pitch circle diameter: φ26.8 mm), The number of teeth (the number of teeth on the helical spline of the output arm) is set to 22 (module: 1.00, pitch circle diameter: φ22.5 mm), and the outer diameter of the output-side helical spline is reduced.

  When assembling the input arm and output arm of such spline specifications and the slider gear, the input arm and the output arm are mistakenly shifted by one tooth in the same direction (one direction of small working angle or one direction of large working angle). In this case, the phase between the input arm and the output arm is shifted by 2.6 °. That is, the angle of one tooth of the input side helical spline is [360 ° / 26 teeth → 13.8 ° / tooth], and the angle of one tooth of the output side helical spline is [360 ° / 22 teeth → 16. 4 ° / tooth], the arm phase shifts by the angular difference [16.4 ° -13.8 ° = 2.6 °]. Here, when the phase between the input arm and the output arm is about 3 °, the operating angle of the variable valve mechanism is, for example, 180 ° in the small operating angle direction and 280 ° in the large operating angle direction, An engine abnormality may not be determined (see FIG. 6).

  On the other hand, in this embodiment, the number of teeth of the input side helical spline 43a of the slider gear 43 and the number of teeth of the output side helical spline 43b are the same, and the module of the output side helical spline 43b is replaced with the input side helical spline 43a. The outer diameter of the output side helical spline 43b is made smaller than that of the input side helical spline 43a.

  Specifically, the number of teeth of the input side helical spline 43a (the number of teeth of the helical spline 41b of the input arm 41) is 24, the module is 1.00 (pitch circle diameter: φ24.4 mm), and the output side helical spline 43b The number of teeth (the number of teeth of the helical spline 42b of the output arm 42) is 24, and the module is 0.83 (pitch circle diameter: φ20.1 mm).

  In this way, when the number of teeth of the input side helical spline 43a of the slider gear 43 and the number of teeth of the output side helical spline 43b are made the same, when assembling the slider gear 43, the input arm 41 and the output arm 42, When the input arm 41 and the output arm 42 are shifted by one tooth in the same direction (one direction of the small working angle or one direction of the large working angle), the arm phases of the input arm 41 and the output arm 42 are relatively shifted. Absent.

  When the output arm 42 is shifted by one tooth to the small operating angle side with respect to the input arm 41, the phase between the input arm 41 and the output arm 42 is shifted by 15 ° (360 ° / 24 teeth). Thus, the operating angle of the variable valve mechanism 30 is 0 ° CA (valve stop), and one cylinder surely misfires. Therefore, it is possible to notice an assembly error from the engine abnormality (assembly error).

  When the output arm 42 is shifted by one tooth to the large operating angle side with respect to the input arm 41, the phase of the input arm 41 and the output arm 42 is shifted by 15 °. For example, as shown in FIG. The operating angle of 30 is 308 ° CA (valve lift amount: 13.3 mm), and the piston 12 and the intake valve 21 interfere with each other (a piston stamp is generated).

  Moreover, in this embodiment, since the module of the output side helical spline 43b is made small, the said output side helical spline 43b can be made into the weakest part. As a result, when a piston stamp is generated due to an incorrect assembly on the large working angle side, the output-side helical spline 43b is first damaged (sheared) by the load received from the piston 12. When the output-side helical spline 43b is broken, the relative phase difference between the roller 41a of the input arm 41 and the nose 42a of the output arm 42 becomes a low lift state even if the slider gear 43 is moved to a position where the valve lift amount is increased. Therefore, the engine torque is lower than that during normal assembly. By this torque reduction, the user can know the engine abnormality.

  In the conventional structure, the weakest part is a pin that connects the slider gear to the control shaft. In this case (when the pin is the weakest part), if the piston stamp is generated due to incorrect assembly to the large working angle side and the pin is damaged, the damaged pin is held as it is, so the valve behavior is abnormal. May not appear and the user may not know the abnormality.

  Here, the number of teeth of the input-side helical spline 43a and the output-side helical spline 43b of the slider gear 43 is the same as that described above when the output arm 42 is shifted by one tooth from the input arm 41 to the large working angle side or the small working angle side. The number of teeth that causes a valve stamp or misfire, specifically, 24 teeth or less. FIG. 6 shows the operating angle when the number of teeth of the input-side helical spline 43a and the output-side helical spline 43b is 24 or less.

-Other embodiments-
In addition, embodiment disclosed this time is an illustration in all the points, Comprising: It does not become a basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, the technical scope of the present invention includes all modifications within the scope and meaning equivalent to the scope of the claims.

  For example, in the above embodiment, the example in which the present invention is applied to the variable valve mechanism for changing the valve characteristic of the intake valve 21 has been described. The present invention may be applied to a valve mechanism.

  The present invention is applicable to a variable valve mechanism that changes the valve characteristics of an internal combustion engine (engine).

DESCRIPTION OF SYMBOLS 1 Engine 10 Cylinder 11 Cylinder head 12 Piston 21 Intake valve 22 Exhaust valve 23 Intake camshaft 23a Intake cam 26 Rocker arm 26a Roller 30 Variable valve mechanism 31 Rocker shaft 32 Control shaft 33 Actuator 40 Variable valve lift mechanism 41 Input arm 41a Roller 41b Helical spline 42 Output arm 42a Nose 43 Slider gear 43a Input side helical spline 43b Output side helical spline

Claims (1)

A control shaft movable in the axial direction;
A slider gear that is movable in the axial direction in conjunction with the control shaft, and has an input side helical spline and an output side helical spline formed on the outer periphery,
An input arm having a roller and having an inner periphery formed with a helical spline that meshes with the input side helical spline of the slider gear;
An output arm having a nose and formed with a helical spline that meshes with an output-side helical spline of the slider gear,
In the variable valve mechanism configured such that the relative phase difference between the roller of the input arm and the nose of the output arm changes according to the movement of the slider gear in the axial direction,
The number of teeth of the input side helical spline of the slider gear and the number of teeth of the output side helical spline are the same, and the module of the output side helical spline is smaller than the module of the input side helical spline. Variable valve mechanism.

Images