JP3479952B2 - Engine gear train structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear train structure for an engine. 2. Description of the Related Art In a gear train structure for transmitting a driving force from a general crankshaft via a gear, noise (gear noise) caused by meshing of the gears has conventionally been a problem. As a method for reducing gear noise that has been conventionally adopted as a preventive measure, the following 5 methods are used.
Two measures have been taken. That is, the accuracy of the tooth surface of the gear is improved by the use of a toothed gear or the like, and the variation in the collision between the teeth is reduced. [0003] Backlash is reduced by adding a fiction gear or scissors gear. Increase the meshing ratio between gears. A member having a high damping ability is used. The distance from the gear rib to the hub, that is, the path through which the vibration is transmitted is lengthened. In such a conventional engine gear train structure, for example, as disclosed in Japanese Patent Application Laid-Open No. 56-154109, an injection pump is driven by a driving force from a crankshaft via a gear and a crank transmission. Conveyed
In a structure in which a camshaft receives a driving force from an injection pump through a toothed belt transmission, a toothed belt transmission has been proposed as a belt that attenuates angular velocity fluctuations from the injection pump. Further, as disclosed in Japanese Utility Model Laid-Open Publication No. 2-72303, an annular friction gear is provided on one side of an idler gear, and a spring member for pressing the friction gear against one side of the idler gear. There are proposed backlash gears. [0006] However, in each of the conventional examples configured as described above, Japanese Patent Application Laid-Open No.
The technique disclosed in Japanese Patent No. 4109 has a problem that the angular velocity fluctuation is adversely amplified due to the resonance of the belt. In the technique disclosed in Japanese Utility Model Laid-Open No. 2-72303, the backlash is reduced to reduce the impact between the teeth due to the angular velocity fluctuation. There is a problem that it cannot be expected. Accordingly, the gear train structure of the engine according to the present invention has been made in view of the above-mentioned circumstances, and has as its object the purpose of the present invention. An object of the present invention is to provide a gear train structure of an engine that reduces rattling noise generated in the engine. [0008] To solve the above problems,
In order to achieve the object, the engine gear train structure of the present invention is provided with a first gear to which a driving force is transmitted from a crankshaft.
When the driving force is applied by meshing with the first gear
Both are rotations that drive the plunger pumping type fuel injection pump
A load for driving the pump is attached to the shaft.
And a second gear, which is coaxially rotated with the second gear.
And from the crankshaft via the second gear
Pump pump that drives the pump by transmitting the driving force
A first rotating body composed of
A cam pulley that drives the camshaft by transmitting the driving force
A second rotating body, and the first and second rotating bodies
A tension member wound by an endless timing belt
And the pump pulleys are circumferentially spaced at a predetermined angle from each other.
And the inner pulley fitted rotatably
And an inner pulley, wherein the inner gear is a second gear.
And driven from the second gear
The outer pulley is connected to the timing belt
Is wound, and the outer peripheral portion of the inner pulley and the outer tap
And the inner periphery of the coil with an elastic member.
A torsion resonance frequency based on a load of the second gear;
By setting the wave number to an attenuating value, the second gear
It is characterized by absorbing torsional resonance generated on the rotating shaft of (1 ). As described above, since the engine gear train structure according to the present invention is constituted, the first rotating body is provided with the first rotating body. By providing means for absorbing torsional resonance generated on the rotation shaft of the second gear based on torque fluctuations of the second rotating body, rattling noise between gears generated in the first gear and the second gear can be reduced. Can be reduced. Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front view showing a gear train structure of an engine according to an embodiment of the present invention.
FIG. 2 shows a part of the gear train structure of FIG.
It is the figure seen from the direction. As shown in FIGS. 1 and 2, the gear train structure shown as an example is interlocked with a crankshaft timing gear (hereinafter referred to as a timing gear) 1 to which a driving force is applied from a crankshaft (not shown) and a timing gear 1. The idle gear 2 which is supported by the shaft, an idle gear 3 which is also interlocked with the idle gear 2, a vacuum pump gear 4 and a fuel injection pump gear (hereinafter referred to as FIP gear) 10 which is interlocked with the idle gear 3, a FIP gear 10 and a rotating shaft. And a camshaft driving pulley 50 to which a driving force is transmitted from the FIP pulley 20 via a timing belt 70, and an idler 60 for applying a constant tension to the timing belt 70. This is the gear train structure of the engine part. Each of the idle gears 2 and 3 has a predetermined gear ratio, and is provided to convert the rotation speed transmitted from the timing gear 1 and transmit the rotation number to the vacuum pump gear 4 or the FIP gear 10 at a predetermined timing. Gear. FI that meshes with and interlocks with idle gear 3
An FIP pulley 20, which is axially mounted on the P gear 10 so that its rotation axis is the same, is fixed by mounting bolts 11a to 11d. That is, the FIP pulley 20 is a pulley that rotates together with the FIP gear 10. The camshaft driving pulley 50 is mounted on the camshaft 51 by mounting bolts 52, and
A rotational force is supplied from the P pulley 20. The idler 60 rotatably abuts the timing belt 70 by means of a bearing 62 and has a function of a tension adjusting mechanism for applying a constant tension. The tension can be adjusted by a spring 61. <Structure of FIP pulley> Next, referring to FIGS.
The configuration of the FIP pulley 20 will be described. FIG.
It is a front view showing the details of IP pulley. Also, FIG.
FIG. 4 is a sectional view taken along the line XX in FIG. 3. 3 and 4,
The FIP pulley 20 of the present embodiment includes an inner pulley 20a forming an inner portion and an outer pulley 2 forming an outer portion.
0b, which are fitted relatively slidably in the circumferential direction by a predetermined angle. The boss portion of the inner pulley 20a has four fixing bolt holes 26a-2
6d are formed, and as shown in FIG.
The FIP gear 10 is attached by 1d. On the other hand, the outer pulley 20b is provided with the toothed portion 25 for the timing belt.
Is formed, and the timing belt 70 is wound. In the outer pulley 20b, the FI
In the opening opposite to the side where the P gear 10 is mounted,
A radially enlarged portion 20c extending in the radial direction of the pulley is formed, and a circumferential groove is formed by the peripheral edge of the inner pulley located at the corresponding position. An annular elastic member 22 made of elastic rubber or the like is mounted in the groove. The elastic member 22 has an inner peripheral portion and an inner pulley adhesive portion 23 fixed to each other, and an outer peripheral portion and an outer pulley adhesive portion 24 fixed to each other with a fixing adhesive. Further, as shown in FIG. 3, on the sliding surface between the inner pulley and the outer pulley, a convex portion 21 formed on the inner pulley and a concave portion 27 formed on the outer pulley are fitted with a predetermined gap H. . This gap is set to about 2 mm so that the injection timing of the fuel injection pump and the opening / closing timing of the valve do not significantly shift. <Damping Function by Angular Velocity Fluctuation Absorbing Means> Next, the damping action of angular velocity fluctuation and torsional resonance by the configuration of the FIP pulley shown in FIGS. 3 and 4 will be described. (Attenuation of Angular Velocity Fluctuation) In general, gear rattling noise that causes noise is caused by angular velocity fluctuation due to torque fluctuation generated in the shaft when the valve is pushed up and down while the camshaft is rotating. . FIG. 9 is a diagram showing torque fluctuation values of the camshaft and the FIP pulley in terms of engine speed. In FIG. 9, the torque fluctuation value at the camshaft is substantially constant irrespective of the change in the engine speed, whereas the torque fluctuation at the FIP pulley increases as the engine speed increases. This is because, as the engine speed increases, torque fluctuation is transmitted from the camshaft, and the load for driving the fuel injection pump increases. However, FI
The rattling noise of the P gear is canceled out by the noise from the engine at a predetermined engine speed. In other words, if the torque fluctuation can be reduced in the engine rotation range where the rattling noise from the FIP gear is higher than the noise from the engine, the noise from the FIP gear can be reduced. FIG. 5 shows that the FIP gear 10
FIG. In FIG. 5, first,
The driving force transmitted from the crankshaft is transmitted to the inner pulley 20a via the FIP gear 10. Then, the inner pulley 20a is rotated relatively to the outer pulley by the torque applied from the gear 10, and the elastic member 22 shown in FIG.
Are elastically deformed in the circumferential direction. By utilizing the elastic deformation of the elastic member, the angular velocity fluctuation transmitted from the FIP gear to the FIP pulley is attenuated. That is, the elastic body fulfills the function of the angular velocity fluctuation absorbing means. Further, the angular velocity fluctuation of the FIP drive shaft is further amplified by the resonance frequency of the belt transmitted from the camshaft driving pulley and the timing belt stretched over the FIP pulley. The frequency is also attenuated. The amount of deformation of the elastic member is the relative rotation angle of the inner pulley with respect to the outer pulley, and is equal to the gap of the stopper member formed on the sliding surface between the inner pulley and the outer pulley as described with reference to FIGS. It will rotate relatively. Since the elastic body of this embodiment is made of a material such as rubber, it is destroyed when a torque equal to or more than a predetermined value is applied (exceeds the rigidity limit value), or the inner and outer are bonded to each other. The part will be peeled off. Therefore, destruction or peeling is prevented by the stopper member. FIG. 6 is a diagram showing the damping action of angular velocity fluctuation by providing the means for absorbing angular velocity fluctuation. As is clear from FIG. 6, the provision of the elastic body attenuates the angular velocity fluctuation transmitted from the FIP pulley to the FIP gear and attenuates the resonance frequency of the cam pulley and the belt stretched over the FIP pulley. (Attenuation of Torsional Resonance) On the other hand, as shown in FIG. 5, the fuel injection pump drive shaft 12 has a relatively long shaft length.
This is a structure in which the driving resistance of the FIP pulley is added at a position eccentric to the rotation center of the shaft (a position far from the rotation center). Therefore, when the driving force is transmitted to the FIP gear, a torsional stress acts on the FIP drive shaft that supports the gear, and the shaft is vibrated by this stress, causing a torsional resonance phenomenon. FIG. 10 is a diagram showing the angular speed fluctuation values of the camshaft and the FIP pulley in terms of engine speed. In FIG. 10, the point at which the angular velocity fluctuation value is maximum between the camshaft and the FIP drive shaft (when the engine speed is approximately 2300 rpm to 250
0 rpm) is the respective torsional resonance point. Here, the reason why the torsional resonance point is slightly shifted between the camshaft and the FIP drive shaft is that the resonance frequency of the timing belt stretched between the cam pulley and the FIP pulley is transmitted to the FIP drive shaft side. That's why. FIG. 7 is a diagram showing the distribution of angular displacement acting on each of 10 points (P1 to P10) on the FIP drive shaft. In FIG.
The torsional resonance of the FIP drive shaft occurs at the point Y in the figure as a boundary point, and the further away from the FIP gear (P10 in FIG. 17).
) The amplitude increases. Therefore, the elastic body and the stopper member provided as angular velocity fluctuation absorbing means provided on the FIP pulley attenuate the torsional resonance and the resonance frequency of the timing belt. (Setting of Elastic Modulus of Elastic Body) FIG.
FIG. 4 is a diagram illustrating a torsional resonance frequency of a P drive shaft by a rotation speed of the shaft. In FIG. 8, the elastic modulus of the elastic body is FI
It is necessary to attenuate the torsional resonance frequency of about 200 Hz or more when the rotation speed of the P drive shaft becomes maximum (point A). That is, it is necessary to attenuate a resonance frequency equal to or higher than the frequency at the intersection A 'between the point A, which is the rotational speed at which the angular velocity fluctuation at which the torsional resonance occurs in FIG. However, in this case, the cylindrical face cam surface 1 which is a connecting portion between the FIP drive shaft and the FIP.
3 (see FIG. 5), the torsional resonance frequency can be reduced by increasing the moment of inertia. If the moment of inertia on the face cam surface is set to approximately twice that of the present state by utilizing this effect, the torsional resonance frequency is reduced. The frequency becomes a value closer to 166 Hz. That is, in FIG. 10, the resonance frequency 16 at the rotation speed at which the angular velocity fluctuation at which the torsional resonance occurs is maximized.
6 Hz (the point where the engine speed becomes about 2500 rpm). Therefore, the spring constant (hardness of rubber) of the elastic body is set so that the torsional resonance frequency is attenuated between 150 Hz and 200 Hz. <Effects of the Embodiment> In the structure of the above-described embodiment, the gear corresponding to the tip end portion with respect to the crankshaft and receiving the exciting force is provided with an angular velocity fluctuation absorbing means constituted by an elastic member. As a result, gear noise generated due to angular velocity fluctuation can be reduced. In addition, the elastic member absorbs fluctuations in angular velocity up to a predetermined allowable angle that can be deformed by elasticity, and sets the elastic coefficient of the elastic member so as to be compatible with the torsional resonance frequency of the drive shaft. When the angle is smaller than the allowable angle, the elastic member reduces (attenuates) the angular velocity fluctuation and the torsional resonance frequency. When the angle exceeds the allowable angle, the stopper member prohibits further rotation of the pulley, Destruction can be prevented. That is, according to the engine gear train structure of the present embodiment, it is possible to reduce the rattling noise generated between the gears due to the angular velocity fluctuation of the rotating shaft due to the torque fluctuation and the torsional resonance. The present invention can be applied to a modification or a modification of the above embodiment without departing from the spirit thereof. For example, in the present embodiment, the gear receiving the exciting force corresponding to the tip end portion with respect to the crankshaft is the FIP gear. However, the gear of the present embodiment is used in other places where the gear rattle is generated. May be used. As described above, according to the engine gear train structure of the present invention, the first rotating body is provided with the rotating shaft of the second gear based on the torque fluctuation of the second rotating body. By providing the means for absorbing the torsional resonance generated in the first gear and the second gear, the rattling noise of the gears generated in the first gear and the second gear can be reduced. [0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing a gear train structure of an engine according to an embodiment of the present invention. FIG. 2 is a view of a part of the gear train structure of FIG. FIG. 3 is a front view showing details of an FIP pulley. FIG. 4 is a sectional view taken along the line XX of FIG. 3; FIG. 5 is an overall view when an FIP gear is mounted on a FIP pulley. FIG. 6 is a diagram showing the damping action of angular velocity fluctuation by providing an angular velocity fluctuation absorbing means. FIG. 7 is a diagram showing angular displacements acting on respective locations at arbitrary 10 locations on the FIP drive shaft. FIG. 8 is a diagram showing a torsional resonance frequency by the number of rotations of a FIP drive shaft. FIG. 9 is a diagram showing torque fluctuation values of a camshaft and a FIP pulley in terms of engine speed. FIG. 10 is a diagram showing angular velocity fluctuation values of a camshaft and a FIP pulley in terms of engine speed. [Description of Signs] 1 ... Crankshaft timing gear, 2, 3 ... Idle gear, 4 ... Vacuum pump gear, 10 ... Gear for driving fuel injection pump, 11a to 11d ... FIP pulley mounting bolt, 12 ... Drive shaft for fuel injection pump , 20: FIP pulley, 21: Inner pulley protrusion (stopper member), 22:
Angular velocity fluctuation absorbing means, 23: inner pulley bonding portion, 24
... Outer pulley bonding part, 25 ... Timing part for timing belt, 27 ... Outer pulley concave part (stopper member), 50 ...
Pulley for driving the camshaft, 60 ... idler, 70 ... timing belt.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Shibakawa 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. −68540 (JP, U) JP-A 6-45132 (JP, U) JP-A 4-109432 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 67/04 F02B 67/06 F02B 77/00 F01L 1/02 F02M 39/02 F16F 15/10 F16F 15/12 F16H 1/06 F16H 55/36

Claims (1)

(57) [Claim 1] The first in which the driving force is transmitted from the crankshaft.
And a driving force is applied by meshing with the first gear,
Axle on the rotating shaft that drives the plunger pumping type fuel injection pump
The load is applied to drive the pump.
And the second gear and the second gear.
A driving force is transmitted from the rank shaft via the second gear.
A first pump comprising a pump pulley for driving the pump
And the camshaft receiving the driving force transmitted from the rolling element and the first rotating body.
A second rotating body composed of a cam pulley for driving the shaft and the first and second rotating bodies, an endless timing base.
And a tension member wound around the pump pulley , wherein the pump pulleys are circumferentially relative to each other by a predetermined angle.
Inner pulley and outer pulley fitted rotatably
And the inner pulley rotates coaxially with the second gear.
And the driving force is transmitted from the second gear.
The timing belt is wound around the outer pulley.
Is, the inner peripheral portion of the outer peripheral portion of the In'napuri Autapuri
Are joined by an elastic member, and the elastic coefficient of the elastic member is
Attenuating the torsional resonance frequency based on the load of the second gear
By setting the value to a certain value, the rotation of the second gear
An engine gear train structure that absorbs torsional resonances that occur .