JP2006002841A - Vibration damping mechanism of rotary shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration damping mechanism capable of providing a sufficient damping force at low revolution of a rotary shaft while suppressing an excessive damping force at high revolution, with no growth in diameter or size of the rotary shaft. <P>SOLUTION: A rotary shaft 2 of the vibration damping mechanism is provided with a flange 4 which is stored in a housing 5 filled with viscous fluid 6. The vibration damping mechanism comprises a movable stirring resistor 22 which is so provided in the flange 4 for rising and setting as to be housed in the flange 4 by the centrifugal force caused by rotation of the rotary shaft 2, and an elastic body 24 which energizes the stirring resistor 22 so that the stirring resistor 22 protrudes from the flange 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vibration damping mechanism for a rotating shaft that attenuates vibration of a rotating shaft such as an engine camshaft by the viscosity of a fluid. It relates to the thing which aimed at coexistence with the suppression effect.

  Conventionally, as a mechanism for attenuating vibration in the rotational direction of a rotating shaft accompanied by torque fluctuation, for example, there is a vibration damping mechanism for an engine cam shaft. The cam shaft vibration damping mechanism is used to reduce engine noise.

  Engine noise resulting from camshaft vibration includes valve sound and cam gear rattling noise. In particular, the cam gear rattling noise is generated when the vehicle is idle, and the noise becomes a problem in convenience store delivery in towns where the vehicle is often idle stopped. The cam gear rattling noise is generated due to large torque fluctuations that occur in the camshaft during low-speed rotation such as idle.

  In general, in order to reduce engine noise such as valve sound caused by cam shaft vibration, damping force is applied to the cam shaft. For applying the damping force to the camshaft, for example, a camshaft vibration damping mechanism as shown in FIGS. 4 and 5 is used.

  In the cam shaft vibration damping mechanism 31 shown in FIG. 4, a flange 4 is provided on the cam shaft 2 driven by a cam gear (not shown), and the flange 4 includes a cylinder head 7 and a cap 9. Stored in the housing 5. Lubricating oil 32 is supplied and filled in the housing 5 through an oil hole 11 formed in the cylinder head 7. A damping force is applied to the camshaft 2 by the viscosity of the lubricating oil 32 (see, for example, Patent Document 1).

  The cam shaft vibration damping mechanism shown in FIG. 5 has a viscous damper 34 provided at the tip of a cam gear (not shown). The viscous damper 34 includes housings 36a and 36b filled and sealed with a viscous fluid 35, and a rotating disk 38 accommodated in the housings 36a and 36b, and includes a camshaft 2 and a cam gear (not shown). Are connected via a rotating disk 38. In the vibration damping mechanism of FIG. 5 as well, the damping force is applied to the camshaft 2 due to the viscosity of the viscous fluid 35, similarly to the vibration damping mechanism 31 shown in FIG. In the viscous damper 34, high-viscosity silicon oil or the like is used as the viscous fluid 35.

  By the way, since the camshaft 2 is driven by the crankshaft via the gear mechanism, application of excessive damping force to the camshaft 2 may deteriorate the fuel consumption of the engine. In particular, the torque fluctuation generated on the camshaft when the engine rotates at a high speed is smaller than that when the engine rotates at a low speed. Therefore, it is desirable to suppress the damping force applied to the camshaft 2 when the engine rotates at a high speed.

  Therefore, the vibration damping mechanism of the cam shaft 2 is required to achieve both a vibration damping effect when the cam shaft 2 rotates at a low speed and a damping force suppression effect when the cam shaft 2 rotates at a high speed.

JP-A-8-158823

  However, the vibration damping mechanism 31 shown in FIG. 4 gives the camshaft 2 a damping force that is not so great due to the viscosity of the lubricating oil 32 in consideration of the fuel consumption of the engine, and deteriorates the fuel consumption at the time of high engine rotation. Although not allowed, the damping force is insufficient to suppress large torque fluctuations at low revolutions.

  On the other hand, the viscous damper 34 as shown in FIG. 5 can provide a damping force that suppresses a large torque fluctuation at the time of low rotation by using a dedicated viscous fluid 35 having a high viscosity. The force becomes resistance when the engine is running at a high speed, which worsens fuel consumption. If the viscous damper 34 is added to the camshaft 2, the camshaft 2 is increased in diameter and size.

  Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide a sufficient damping force when the rotating shaft is rotated at a low speed without increasing the diameter and size of the rotating shaft, and an excessive damping force at a high speed. An object of the present invention is to provide a vibration damping mechanism for a rotating shaft that can be suppressed.

  In order to achieve the above object, the present invention provides a rotary shaft vibration damping mechanism configured by providing a rotary shaft with a flange and storing the flange in a housing filled with a viscous fluid. The stirring resistor that is movable so as to be housed in the flange by centrifugal force generated by the rotation of the rotating shaft, and the stirring resistor is attached so that the stirring resistor protrudes from the flange. And an elastic body.

  Preferably, the moving direction of the stirring resistor is set so as to obliquely intersect the axis of the rotation shaft at a predetermined inclination angle.

  Preferably, the stirring resistor is provided at a position outside the flange in the radial direction.

  Preferably, an inclined hole formed in the flange and extending radially outward of the rotating shaft, a pin member that is movably inserted into the inclined hole and forms the stirring resistor, and provided in the inclined hole And a coil spring forming the elastic body.

  The rotating shaft may be a cam shaft of a valve mechanism of an engine.

  According to the present invention, a sufficient damping force is applied by projecting the stirring resistor when the rotating shaft rotates at a low speed without increasing the diameter and size of the rotating shaft, and a centrifugal force when the rotating shaft rotates at a high speed. Thus, excessive damping force can be suppressed by storing the stirring resistor in the flange.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a vibration damping mechanism for a rotating shaft according to this embodiment, and shows a state when the rotating shaft is rotating at a low speed. FIG. 2 shows the vibration damping mechanism of the rotating shaft of the present embodiment, and shows a state when the rotating shaft is rotating at a high speed. 3A is a partially enlarged view of the flange of FIG. 1, and FIG. 3B is a partially enlarged view of the flange of FIG. In FIG. 1, FIG. 2, FIG. 3 (a) and FIG. 3 (b), the same elements as those shown in FIG. 4 and FIG.

  In the present embodiment, the vibration damping mechanism for a rotating shaft according to the present invention is applied to a cam shaft of a valve mechanism of an engine.

  An outline of the camshaft 2 that is a target of the vibration damping mechanism 1 of the rotating shaft according to the present embodiment will be described with reference to FIGS. 1 and 5. A cam shaft 2 having a plurality of cams 39 is supported on the upper portion of the cylinder head 7, and a cam gear (not shown) is provided at one end of the cam shaft 2. The cam gear meshes with an idle gear, and the idle gear meshes with a crank gear provided on the crankshaft (not shown). The rotation of the crankshaft is transmitted to the camshaft 2 by these gear mechanisms.

  As shown in FIG. 1 and FIG. 2, the vibration damping mechanism 1 of the rotating shaft includes a flange 4 provided on the cam shaft 2 and a housing 5 that houses the flange 4. Fluid 6 is filled.

  In the present embodiment, the housing 5 is formed on an upper portion of the cylinder head 7, and is configured by an upward concave housing base 8, and placed on the top of the housing base 8, and a downward concave cap 9. The The housing 5 is filled with engine lubricating oil 32 which is a viscous fluid 6. The lubricating oil 32 is supplied from an oil passage provided in the camshaft 2 or the housing 5. In the present embodiment, the lubricating oil 32 is supplied from the oil hole 11 provided in the housing base 8. Further, the penetrating portion of the cam shaft 2 with the housing 5 is a shaft seal, and the leakage of the lubricating oil 32 from the gap between the cam shaft 2 and the housing base 8 and the cap 9 is very small.

  The flange 4 according to the present embodiment includes a disk portion 12 that extends radially outward from the cam shaft 2 and a protruding portion 14 that protrudes in the axial direction from a radially outer position of the disk portion 12. The side surface of the disk portion 12 is orthogonal to the axis of the cam shaft 2, and the protruding portion 14 protrudes from the outer peripheral end of one side surface of the disk portion 12 over the entire circumference and has a cylindrical shape. As described above, the flange 4 is formed in a short cylindrical shape in which one side (left side in FIG. 1) is opened and the other side (right side in FIG. 1) is closed.

  In particular, the vibration damping mechanism 1 of the rotating shaft of the present embodiment is provided so as to be able to protrude and retract in the flange 4 as shown in FIGS. 1, 3 (a) and 3 (b), and by rotating the cam shaft 2. A stirring resistor 22 that is movable so as to be accommodated in the flange 4 by centrifugal force, and an elastic body 24 that biases the stirring resistor 22 so that the stirring resistor 22 protrudes from the flange 4 are provided. .

  Specifically, the vibration damping mechanism 1 of the rotating shaft of the present embodiment is formed in the flange 4 and extends into the radially outer side of the cam shaft 2 and is movably inserted into the inclined hole 21. The pin member 25 that forms the stirring resistor 22 and the coil spring 26 that is provided in the inclined hole 21 and forms the elastic body 24 are provided.

  The inclined hole 21 of the present embodiment is provided at the outer peripheral end portion of the disk portion 12 of the flange 4 and penetrates the disk portion 12 at a predetermined inclination angle θ that obliquely intersects the axis of the cam shaft 2. . More specifically, the inclined hole 21 extends radially outward from the side surface of the disk portion 12 on the inner side of the flange at an inclination angle of approximately 45 ° (θ≈45), and extends outward from the flange 4. It opens at the corner of the disk part 12 at Further, the inclined hole 21 is formed in a circular shape in cross section, and is specifically a drill hole. Further, a screw thread 28 is formed at the outer end of the inclined hole 21 in the radial direction of the cam shaft 2. In the present embodiment, the inclined holes 21 described above are formed at four locations at intervals of 90 ° in the circumferential direction.

  The pin member 25 of the present embodiment has a cylindrical shape extending along the extending direction of the inclined hole 21 and has an outer diameter slightly smaller than the inner diameter of the inclined hole 21. Further, the pin member 25 can move smoothly in the inclined hole 21. Therefore, the moving direction of the pin member 25 has the same inclination angle θ as the inclination angle of the inclined hole 21. In other words, the pin member 25 is provided on the outer side in the radial direction of the flange 4, and the moving direction thereof is set so as to obliquely intersect the axis of the cam shaft 2 at an inclination angle θ.

  The coil spring 26 of the present embodiment is provided so as to extend and contract in the extending direction of the inclined hole 21, and is positioned on the outer side in the radial direction from the pin member 25. One end of the coil spring 26 is fixed to the end surface on the radially outer side of the pin member 25.

  Further, a stop plug 29 is fixed to the radially outer end of the inclined hole 21, and the other end of the coil spring 26 is fixed to the stop plug 29. The coil spring 26 urges the pin member 25 radially inward (from the lower right to the upper left in FIG. 3A).

  The stopper plug 29 of the present embodiment is a cylindrical member having a male thread that is screwed with the thread 28 of the inclined hole 21, and the stopper plug 29 has a lubricating oil 32 by the piston action of the pin member 25. A discharge hole 30 is provided so as to allow entry and exit.

  Thus, the pin member 25, the coil spring 26, and the stopper plug 29 become an integral part. For example, by welding the coil spring 26 to the pin member 25 and the stopper plug 29, they are joined to each other.

  The pin member 25, the coil spring 26, and the stopcock 29 joined in this way are provided in each inclined hole 21 formed at a plurality of locations in the circumferential direction of the flange 4 (four locations in the present embodiment). The amount of protrusion of the pin member 25 from the inclined hole 21 is determined by the balance between the centrifugal force (inertial force) caused by the rotation of the cam shaft 2 and the spring force of the coil spring 26.

  Next, the operation of the vibration damping mechanism 1 for the rotating shaft of the present embodiment will be described.

  As shown in FIG. 3A, when the rotational speed of the camshaft 2 is relatively low (for example, idle rotational speed), the centrifugal force acting on the pin member 25 is small. The pin member 25 is held in a state in which a part thereof protrudes from the inclined hole 21 (the protrusion amount of the pin member 25 is relatively large).

  Therefore, when the cam shaft 2 rotates at low speed, the lubricating oil 32 is stirred by the protruding pin member 25, and the damping force on the cam shaft 2 is further increased by the stirring resistance. Therefore, a large torque fluctuation of the camshaft 2 that occurs at the time of low rotation is buffered.

  As the rotational speed of the cam shaft 2 increases, the centrifugal force acting on the pin member 25 increases. The coil spring 26 is compressed by the increased centrifugal force, and the protruding amount of the pin member 25 from the inclined hole 21 is reduced. Further, when the rotational speed of the camshaft 2 increases and exceeds the predetermined rotational speed, the pin member 25 is completely stored in the inclined hole 21 against the spring force (see FIG. 3B).

  Therefore, when the camshaft 2 rotates at a high speed, the amount of protrusion of the pin member 25 decreases compared to when the camshaft 2 rotates at a low speed, thereby reducing the damping force due to the stirring resistance of the pin member 25. In particular, in the present embodiment, when the rotational speed of the camshaft 2 is equal to or higher than a predetermined rotational speed, the pin member 25 is completely stored, so that the damping force by the pin member 25 disappears.

  As described above, the vibration damping mechanism 1 of the rotating shaft according to the present embodiment provides a sufficient damping force when the cam shaft 2 rotates at a low speed without increasing the diameter and size of the cam shaft 2, and An excessive damping force can be suppressed during high rotation. That is, it is possible to achieve both the vibration damping effect when the camshaft 2 rotates at a low speed and the stirring resistance (damping force) suppressing effect when the camshaft 2 rotates at a high speed.

  Specifically, by applying a sufficient damping force at low rotation, it is possible to buffer large fluctuation torque generated on the camshaft 2 at low rotation, and engine noise such as valve system noise, particularly cam gear rattling. Sound can be reduced.

  Further, by suppressing an excessive damping force at the time of high rotation, it is possible to prevent deterioration of fuel consumption at high rotation of the engine.

  In particular, since the pin member 25 moves obliquely with respect to the axis of the cam shaft 2, the protruding amount of the pin member 25 can be set large. For example, if a hole is provided in the protruding portion 14 so that the pin member moves perpendicularly to the axis of the cam shaft 2, the length of the hole is short, or the pin member interferes with the cam shaft 2. For this reason, the protruding amount of the pin member must be set small. In this embodiment, since the hole is inclined (inclined hole 21), the length of the hole and the length of the pin member 25 can be made longer, and the protruding amount of the pin member 25 is set larger. be able to.

  By providing the pin member 25 on the radially outer side of the flange 4, the protruding amount of the pin member 25 can be set larger without causing the pin member 25 to interfere with the cam shaft 2.

  By configuring the flange 4 to include the protruding portion 14 extending in the axial direction, a gap having a predetermined width is formed between the outer peripheral surface of the protruding portion 14 and the inner wall surface of the housing 5 facing the protruding portion 14. A damping force can be applied to the camshaft 2 by the lubricating oil 32 in the gap.

  By configuring the pin member 25, the coil spring 26, and the stopper plug 29 as an integral part, handling of the pin member 25 and the like can be facilitated, and the assembling property with respect to the flange 4 can be improved. it can.

  The vibration damping mechanism 1 of the rotating shaft of the present embodiment has a relatively simple structure as described above, and can be manufactured easily and inexpensively.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, in the present embodiment, the mode for the cam shaft 2 driven by the gear mechanism has been described, but the rotation shaft targeted by the present invention is not limited to the cam shaft. Further, the driving means of the rotating shaft is not limited to the gear mechanism, and other means such as a pulley can be used.

  In this embodiment, although the form which uses the coil spring 26 as the elastic body 24 was demonstrated, it is not limited to this, For example, a disc spring, rubber | gum, etc. may be sufficient.

  In the present embodiment, the configuration in which the engine lubricating oil 32 is shared as the viscous fluid 6 has been described. However, the present invention is not limited to this, and it is possible to use viscous fluids having various viscosities such as exclusive oil made of silicon oil. .

  Although this embodiment demonstrated the form which provides the stirring resistor 22 in four places at 90 degree intervals in the circumferential direction, this invention is not limited to the number and arrangement | positioning of a stirring resistor.

  In this embodiment, although the form which uses the cylindrical pin member 25 as the stirring resistor 22 was demonstrated, the shape of a stirring resistor is not limited to this, For example, various shapes, such as a shape like a stirring blade, are possible It is.

  The inclination angle θ in the moving direction of the pin member 25 is preferably within 60 °, and particularly preferably within the range of 30 ° ≦ θ ≦ 45 °, but the present invention is not limited to this.

  In the present embodiment, the mode (see FIG. 3B) in which all of the pin member 25 is stored in the inclined hole 21 when the cam shaft 2 rotates at a predetermined rotational speed or more has been described. Instead, as indicated by an imaginary line in FIG. 3B, when the pin member is stored most in the inclined hole, a part of the pin member may protrude from the inclined hole.

  In the present embodiment, the configuration in which the coil spring 26 is attached to the bottom surface of the pin member 25 (the end surface on the radially outer side of the pin member 25) has been described. For example, a concave portion is formed at the center of the bottom of the pin member. The bottom side may be formed in a cylindrical shape, a coil spring may be attached in the recess, and the coil spring may be accommodated in the recess when the camshaft rotates at a high speed. Thereby, the protrusion amount of a pin member can be further lengthened. Further, since the length of the coil spring can be increased, it is possible to provide redundancy in adjusting the amount of movement of the pin member with respect to the rotational speed of the cam shaft.

The vibration damping mechanism of the rotating shaft by one Embodiment of this invention is shown, and the state which the stirring resistor protruded from the flange is shown. The vibration damping mechanism of the rotating shaft by one Embodiment of this invention is shown, and the state in which the stirring resistor was accommodated in the flange is shown. (A) shows the partially enlarged view of the flange of FIG. 1, (b) shows the partially enlarged view of the flange of FIG. The conventional vibration damping mechanism of a rotating shaft is shown. Fig. 4 shows another conventional vibration damping mechanism for a rotating shaft

Explanation of symbols

1 Vibration damping mechanism of rotating shaft 2 Cam shaft (rotating shaft)
4 Flange 5 Housing 6 Viscous fluid 21 Inclined hole 22 Stirring resistor 24 Elastic body 25 Pin member 26 Coil spring 32 Lubricating oil

Claims (5)

In the vibration damping mechanism of the rotating shaft configured by providing a flange on the rotating shaft and storing the flange in a housing filled with a viscous fluid,
An agitation resistor that is provided in the flange so as to be movable in and out, and is movable so as to be accommodated in the flange by a centrifugal force generated by the rotation of the rotation shaft, and the agitation resistor is protruded from the flange A vibration damping mechanism for a rotating shaft, comprising: an elastic body that biases the stirring resistor.   2. The vibration damping mechanism for a rotating shaft according to claim 1, wherein the moving direction of the stirring resistor is set so as to obliquely intersect the axial center of the rotating shaft at a predetermined inclination angle.   The vibration damping mechanism for a rotating shaft according to claim 1 or 2, wherein the stirring resistor is provided at a position radially outside the flange.   An inclined hole formed in the flange and extending radially outward of the rotating shaft, a pin member that is movably inserted into the inclined hole and forms the stirring resistor, and is provided in the inclined hole. The vibration damping mechanism for a rotating shaft according to any one of claims 1 to 3, further comprising a coil spring that forms an elastic body. 5. The vibration damping mechanism for a rotating shaft according to claim 1, wherein the rotating shaft is a cam shaft of a valve mechanism of an engine.

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