JP2001124184A - Scissors gear device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent uneven abrasion and operational failure caused by a surface swing of a sub-gear in a scissors gear mechanism for interposing a spring for relatively rotatably supporting the sub-gear having the same tooth number and a module adjacently to a main gear and imparting rotational directional energizing force between these main gear and sub-gear. SOLUTION: When the rotational center of a scissors gear is a point O and the action center of force acting on a sub-gear 13 from a spring 17 is a point A, lubricating oil supply passages 82, 83 for supplying lubricating oil to a contact surface of the sub-gear 13 and a main gear 12 are arranged at a point P or the vicinity where an angle AOP measured in the gear rotating direction becomes almost 90 degrees to enhance a lubricating property of the highest contact pressure part between the sub-gear 13 and the main gear 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a scissors gear device used for a rotation transmitting portion accompanied by torque fluctuations and rotation fluctuations, such as driving an engine camshaft or a fuel injection pump.

[0002]

2. Description of the Related Art A scissors gear device is known as a gear mechanism suitable for driving a device that causes torque fluctuation or rotation fluctuation such as a fuel injection pump or a camshaft of an automobile engine. This has a configuration in which sub gears having the same number of teeth and modules are provided adjacent to a main gear provided on a drive shaft so as to be relatively rotatable, and these main gears and sub gears are biased in the rotational direction by elastic bodies. With such a scissors gear device,
Since the backlash is eliminated by the action of pinching the teeth of the mating gear between the tooth surfaces of the main gear and the sub gear which can be relatively rotated elastically, it is possible to smoothly and quietly drive a camshaft or the like that causes torque fluctuation. it can. (Publications of scissors gear devices include, for example,
See JP-A-8456 and JP-A-6-288462. )

[0003]

In such a scissors gear mechanism, an elastic member is provided so as to urge the main gear and the sub-gear in the rotation direction, so that the sub-gear is inclined with respect to the center of the rotation shaft. In such a case, there is a problem that a displacement, that is, a so-called surface blur occurs, and accordingly, abnormal wear occurs at a contact portion with the main gear and poor meshing with a mating gear occurs.

Since the gear noise due to the backlash is more remarkable as the torque fluctuation / rotation fluctuation is larger, it is necessary to set the swing reaction force of the elastic body of the scissors gear to a larger value as the torque fluctuation / rotation fluctuation is larger. However, the above-mentioned problems such as abnormal wear become more remarkable as the tension of the elastic body is increased, so that it is difficult to apply the scissor gear in applications where its effectiveness is expected to be originally higher.

An object of the present invention is to solve such a conventional problem.

[0006]

According to a first aspect of the present invention, a sub gear having the same number of teeth and modules as the main gear is supported adjacent to the main gear attached to the rotating shaft so as to be rotatable relative to the main gear. In a scissors gear mechanism in which an elastic body for applying a biasing force in the rotation direction is interposed between the main gear and the sub gear, a point O is defined as the center of rotation of the scissor gear, and a point A is defined as a center of action of the force acting on the sub gear from the elastic body. At or near the point P where the angle AOP measured in the gear rotation direction is approximately 90 degrees, a lubricating oil supply passage for supplying lubricating oil to the contact surface between the sub gear and the main gear is provided (see FIG. 1). ).

In the second invention, a sub-gear having the same number of teeth and modules as the main gear is supported adjacent to the main gear attached to the rotating shaft so as to be rotatable relative to the main gear. In a scissors gear mechanism with an elastic body that applies a biasing force in the direction of rotation between the scissors gear, the coordinate axis is set on the rotation axis of the scissors gear in a direction where the scissors gear rotation direction is the left-handed screw direction, and the elastic body acts on the sub gear A on the coordinate axis of the acting center point A of the force to be applied, b on the coordinate axis of the acting center point B of the force acting on the sub-gear from the axis rotatably supporting the sub-gear, b The coordinate on the coordinate axis of the acting center point C of the force input to the sub-gear through meshing on the tooth surface from the mating gear is c, Gear the distance from the rotation center O to the point A rs, the distance from the rotation center O to the action center point C r
g, when the pressure angle of the sub gear is α, the angle AOP (rad) measured in the rotation direction of the scissors gear when the relationship of (−a + b) (r _g / r _s ) cos α ≧ bc is satisfied ,

[0008]

(Equation 1) At or near point P that satisfies the condition, a lubricating oil supply passage for supplying lubricating oil to the contact surface between the sub gear and the main gear was provided (see FIGS. 3 and 4).

The scissors gear mechanism of each of the above inventions includes:
A circumferential groove is provided coaxially with the rotating shaft on the opposite end face of the main gear or the sub gear, and locking portions are projected on each of the main gear and the sub gear so as to face the circumferential groove. A configuration in which an elastic body that applies a biasing force in the direction is housed in the circumferential groove can be applied.

[0010]

Operation / Effect Before describing the operation and effect of the present invention, the reason why the sub-gear causes the surface wobbling effect in the conventional scissors gear mechanism will be described in detail. 5 and 6 show a general structure example of the scissors gear device. In the figure, a main gear 12 is fitted and fixed to a rotating shaft 11, and a sub gear 13 having the same number of teeth and modules is rotatably held adjacent to one end surface thereof. The main gear 12 has a sub gear 13
A circumferential groove 16 is formed coaxially with the rotation shaft 11 on the end face facing the shaft, and a C-shaped swing spring 1 is formed therein as an elastic body.
7 is housed. One end of the torsion spring 17 has a circumferential groove 16.
The other end abuts on a pin-shaped engaging portion 14 press-fitted into the sub gear 13 and the other end abuts on a locking portion 15 also press-fitted on the main gear 12.
5 acts on the main gear 12 and the sub-gear 13 in the rotational direction.

Here, the force acting on the sub gear 13 is shown in FIG.
This will be described below. FIG. 7 is a view observed from a viewpoint fixed to the sub gear 13 (a viewpoint rotating with the sub gear 13). In this case, the meshing counterpart gear 18 rotates counterclockwise around the sub gear. While the restoring force Fs of the spring 17 acts on the pin 14 press-fitted into the sub-gear 13, the sub-gear 13
The reaction force Fg of the force pinching the teeth of the mating gear 18 acts.
Since the meshing position is rotated counterclockwise in the figure by the rotation of the sub gear 13, the force Fg acting on the tooth surface is Fg
.., Fg2, Fg3,... Further, since the sub gear 13 is held by the shaft portion 11a, the resultant force of Fs and Fg acts on the shaft portion 11a from the sub gear 13, and the reaction force N acts on the sub gear 13. The point of application of the reaction force N is a fitting portion between the sub gear 13 and the shaft 11a.

FIG. 8 shows the force acting on the sub-gear 13 as viewed from above (observed in the xy plane). Generally, due to the structure of the scissors gear, the point of action of the force acting on the sub-gear from the spring, the point of action of the force input to the sub-gear from the mating gear through the tooth surface, and acts on the sub-gear from the shaft supporting the sub-gear. The points of action of the forces are not coplanar. In particular, the subgear 13 which does not contribute to torque transmission has its tooth width set to be small, so that the meshing center point and the action point of the spring 17 are naturally separated in the axial direction.
Therefore, the spring reaction force Fs and the tooth surface engagement force F
g, the support shaft reaction force N acts on the action points at different positions in the vertical direction in FIG.

In FIG. 8, since the action points of Fs, Fg, and N are not on a straight line parallel to the y-axis, a moment Tz about the z-axis acts on the sub gear 13. The moment Tz tends to rotate the sub gear 13 in the direction of surface deviation. As described above, since the force Fg changes its direction as the sub gear 13 rotates, it becomes an alternating load that changes its magnitude and direction from side to side in FIG. Further, since the support point reaction force N is generated by the combined force of Fg and Fs, the magnitude and direction of N also changes due to the rotation of the sub gear 13.

Here, the y-direction components of Fs, Fg, and N are Fsy, Fgy, and Ny, respectively. The x-coordinate of the acting center of the force Fs input from the spring 17 to the sub-gear 13 is a, and the shaft 11a is the sub-gear 13 Assuming that the x-coordinate of the acting center of the force N input to the sub-gear b is c and the x-coordinate of the acting center of the force Fg inputted to the sub-gear 13 from the mating gear 18 by meshing the tooth surfaces is c, the moment Tz is _{T z = aF sy + bN y} + cF gy ... is (1).

Let the magnitude of Fs be | Fs | and the magnitude of Fg be |
Fg |, the angle between the point of engagement with the counterpart gear 18 and the Z-axis minus direction is CA (the counterclockwise direction is positive in FIG. 7), and the pressure angle of the gear is α, _Fsy = − | F _s |... (2) F _gy = − | F _g | cos (CA-α)... (3) N _y = −F _sy −F _gy = | F _s | + | F _g | cos (CA-α) ... (4)

[0016] Equation (2) is rearranged to (4) into equation _{(1), T z = (} - a + b) | F s | + (b-c) | F g | cos (CA- α) (5)

In the above description, the action of the force in the xy plane has been described with reference to FIG. 8, but as shown in FIG.
Considering the action of the force in the xz plane, a moment Ty about the y axis also acts on the sub gear. Here, when the counterclockwise direction as positive in FIG. 9, the moment Ty is represented by _{T y = -bN z -cF gz ...} (6). Here, Nz is the z-direction component of the support shaft reaction force N, and Fgz is the z-direction component of the force Fg input to the sub-gear from the mating gear through the tooth surface, and is expressed as follows.

F _gz = − | F _g | sin (CA-α) (7) N _z = −F _gz = | F _g | sin (CA-α) (8) Equations (7) to (8) By substituting into Equation (6) and rearranging, _Ty = (c−b) | F _g | sin (CA−α) (9)

The distance between the acting center A of the force Fs inputted to the sub-gear 13 from the spring 17 and the rotation center O of the sub-gear 13 is represented by rs, and the force inputted to the sub-gear 13 from the mating gear 18 by meshing of the tooth surfaces. if the distance between the rotation center O of the action of Fg center C and subsidiary gear 13 and rg, | Fs | and | Fg | _{between, | F s | r s =} | F g | cos (α) r g ... (10)

Therefore, the torque for actually rotating the sub-gear 13 in the direction of surface deflection is the resultant T of the moment Tz about the Z axis and the moment Ty about the y axis.

Here, the moment Tz,
When the time change of Ty is calculated, it becomes as shown in FIG. However, the direction of the moment is positive in the counterclockwise direction in FIGS. The time change of the moment Tz (reference numeral 51) and the moment Ty (reference numeral 52) is a function approximated to a trigonometric function having a substantially sinusoidal shape, and its period coincides with the rotation period of the scissors gear.

FIG. 11 shows a change in the direction and magnitude of the moment T, which is the resultant of the moments Tz and Ty, plotted on the yz plane. The moment T is represented by a vector extending from the origin 61 on FIG. A moment T acts in the right-handed screw direction with respect to the direction of the vector, and its magnitude is represented by the length of the vector. The magnitude and direction of the moment T are determined according to the rotation of the scissor gears 62, 63,.
, But the tip of the vector moves on the circle 64.

When a moment T acts on the sub-gear 13, the sub-gear is slightly rotated in the right-hand direction of the vector using the vector in FIG. 11 as a rotation axis. As a result, there arises a problem that the meshing between the sub gear 13 and the mating gear 18 deteriorates. Further, the sub gear 13 is slightly rotated in the right-hand screw direction about the vector, so that the sub gear 13 and the main gear 12 do not contact with each other on the entire annular surface 19 where both gears are in contact with each other, but on a part of the surface 19. Local contact will be made at 19a. This contact point 1
The position on the angle of 9a corresponds to each vector in FIG.
The position is rotated clockwise by 0 degrees. Since the contact is in a state close to the point contact, the surface pressure increases, and
The main gear 12 and the main gear 12 rub against each other with a slight displacement in the rotation direction, so that an abnormal wear phenomenon such as fretting may occur near the contact portion. (Effects of the First Invention) Therefore, when the center of rotation of the scissors gear is point O and the center of action of the force acting on the sub-gear from the elastic body is point A as in the first invention, the measurement is performed in the gear rotation direction. By providing a lubricating oil supply passage for supplying lubricating oil to the contact surface between the sub gear and the main gear at or near the point P where the angle AOP is approximately 90 degrees, a moment acting on the sub gear in the direction of surface deflection is provided. This makes it possible to supply lubricating oil to the point at which the contact force is maximized when the sub gear makes a slight rotation in the direction of surface deviation and the sub gear and the main gear make point contact at point 19a,
Failure of the scissors gear due to point contact can be effectively prevented. Therefore, the spring reaction force of the scissor gear can be further increased, and the scissor gear can be applied to applications in which torque fluctuation and rotation fluctuation are larger than in the past. (Effect of the Second Invention) By the way, the above-mentioned contact point 19
a, and the magnitude of the contact force at the contact point 19a is represented by y.
FIG. 12 shows a plot on the z plane. In FIG. 12, the direction of the vector extending from the origin 71 indicates the direction from the origin to the contact point 19a, and the length of the vector is the contact point 1
9a shows the magnitude of the force acting between the sub gear 13 and the main gear 12. Since the moment acting on the sub-gear 13 acts in the right-hand screw direction of the vector shown in FIG.
The position of the contact point 19a is in the direction obtained by rotating the vector representing the moment shown in FIG. 11 approximately 90 degrees clockwise, and the force transmitted at the contact point 19a is proportional to the length of the vector shown in FIG. Therefore, FIG. 12 is similar to FIG. 11 obtained by rotating FIG. 11 approximately 90 degrees clockwise. Contact point 1
Although the position of 9a and the magnitude of the contact force change according to the rotation of the scissors gear, in FIG.
73 ... by changing the direction and size. The position of the contact point 19a where the load due to the contact becomes maximum is shown in FIG.
1 is in the positive direction of the y-axis. If the condition (-a + b) (r _g / r _s ) cos α ≧ bc (11) is satisfied, the range of the angle that the contact point 19 a can take is represented by a circle 74 from the origin 71. On the other hand, it is within the range 77 surrounded by the tangent lines 75 and 76 plotted.

This range 77 corresponds to the area of the angle AOP in the second invention. Therefore, according to the second invention, the same effect as that of the first invention can be obtained.
Further, since the present invention supplies the lubricating oil more widely in the range where the point contact can occur as compared with the first invention, it is possible to prevent the trouble due to the point contact other than when the moment in the surface shake direction is maximized. On the other hand, since the range in which the lubricating oil passage should be formed is limited, it is not necessary to supply the lubricating oil to the entire circumferential surface of the contact surface between the main gear 12 and the sub gear 13.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment of the present invention.
This embodiment corresponds to the first aspect of the invention. The scissors gear composed of the main gear 12 and the sub gear 13 rotates clockwise in FIG. The basic configuration is the same as that of FIG. 5, except that the hollow portion 81 exists inside the rotary shaft 11 that supports the scissors gear, and that the outer peripheral portion of the rotary shaft 11 and the hollow portion 81 communicate with each other. The difference is that an oil passage 82 and a lubricating oil passage 83 are formed inside the main gear 12.

The lubricating oil passages 82 and 83 are formed on the horizontal line L in FIG. 1, and are connected to a straight line connecting the pin 14 which is the point of action of the force acting on the sub-gear 13 from the spring 17 to the center of the scissor gear, and the lubricating oil passage 82. , 83 are substantially 90 degrees in the scissors gear rotation direction with reference to the position of the pin 14. Lubricating oil from an oil pump (not shown) is introduced into the hollow portion 81 inside the shaft 11, and the lubricating oil is supplied to the contact surface between the sub gear 13 and the main gear 12 through the lubricating oil passages 82 and 83.

As described above, the reaction force from the spring 17 to the sub-gear 12, the reaction force at the support point acting on the sub-gear 12 from the shaft that freely rotates and supports the sub-gear, and the transmission from the mating gear 18 are transmitted. The force that is exerted acts. Since the positions where these three forces act are different in the thickness direction of the sub-gear 13 (the left-right direction in the side view), a moment acts on the sub-gear in the direction of surface deviation,
Due to the moment, the sub gear is slightly rotated and displaced in the surface blur direction, and the sub gear 13 and the main gear 12 come into point contact. Although the position of the point contact changes according to the rotation of the scissors gear, the position of the contact point when the surface runout moment is maximized is a portion indicated by reference numeral 19b in FIG. In this embodiment, since the lubricating oil is actively supplied to the vicinity of the contact portion (19b) by the lubricating oil passages 82 and 83, problems such as abnormal wear due to point contact and malfunction of the scissors gear are effectively prevented. be able to.

FIGS. 3 and 4 show a second embodiment of the present invention, and correspond to the second embodiment. Main gear 12
FIG. 3 shows a scissors gear composed of
Is assumed to rotate clockwise. The basic configuration is the same as that of the first embodiment, but the configuration of the lubricating oil passage communicating the outer peripheral portion of the rotating shaft 11 and the hollow portion 81 is different. That is, in this case, the lubricating oil passage extending from the hollow portion 81 to the contact portion (19c) passes through the rotating shaft 11, the sub gear supporting portion of the main gear 12, and the sub gear 13, and the lubricating oil passages 91a to 93a and 9a
1b to 93b. In FIG. 3, the angle formed by the first lubricating oil passages 91a to 93a and the second lubricating oil passages 91b to 93b with the horizontal line L is ± sin ^-1 ｛(bc) rs / (− a + b). rgcosα｝. Lubricating oil is pressure-fed to the hollow portion 81 inside the shaft 11, and lubricating oil passages 91a to 93a or 91b
Through 93b, the lubricating oil is supplied to the contact surface between the sub gear 13 and the main gear 12. As described in the description of the prior art, the sub-gear 12 has a reaction force from the spring 17 and a sub-gear 12 from a shaft that freely supports the sub-gear.
And a force transmitted from the mating gear 18 by meshing. Since the positions where these three forces act are different in the thickness direction of the sub-gear 13 (the left-right direction in the side view), a moment acts on the sub-gear in the direction of surface wobble, and the sub-gear is minutely moved in the direction of surface wobble by the moment. Rotationally displaced, sub gear 1
3 and the main gear 12 make point contact. Although the position of the point contact changes according to the rotation of the scissors gear, the range of the contact point is limited to the vicinity of the contact portion (19c).

In this embodiment, two lubricating oil passages 91a are provided.
93a and 91b to 93b, lubricating oil is actively supplied to the vicinity of the contact portion (19c), so that troubles such as abnormal wear due to point contact and adhesion between the sub gear 13 and the main gear 12 are effectively prevented. be able to. Compared to the first embodiment, since the lubricating oil is supplied widely within a range where the point contact can occur, it is possible to prevent the trouble due to the point contact other than when the moment in the surface shake direction is maximized. On the other hand, since the range in which the lubricating oil passage should be formed is limited, it is not necessary to supply the lubricating oil to the entire circumferential surface of the contact surface between the main gear 12 and the sub gear 13.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a first embodiment of the present invention.

FIG. 2 is a side view showing a cross section of the lubricating oil passage shown in FIG. 1;

FIG. 3 is a schematic front sectional view of a second embodiment of the present invention.

FIG. 4 is a side view showing a cross section of the lubricating oil passage shown in FIG. 3;

FIG. 5 is a schematic front sectional view of a conventional scissors gear.

FIG. 6 is a side view showing only the upper half in a cross section.

FIG. 7 is an explanatory diagram of a force acting on a sub gear of a scissors gear.

FIG. 8 is an explanatory diagram of a force acting on a sub gear of a scissors gear.

FIG. 9 is an explanatory diagram of a force acting on a sub gear of a scissors gear.

FIG. 10 is an explanatory diagram showing a change in moment acting on a sub gear of a scissors gear due to gear rotation displacement.

FIG. 11 is an explanatory diagram showing the magnitude and direction of a moment acting on a sub gear of a scissors gear.

FIG. 12 is an explanatory diagram showing the angular position of a point where a sub gear and a main gear of a scissors gear contact, and the magnitude of a force transmitted at the contact point.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Rotation shaft 12 Main gear 13 Sub gear 14 Sub gear side pin 15 Main gear side pin 16 Circular groove 17 Spring (elastic body) 18 Opponent gear 19 Contact part 51 Moment Tz 52 Moment Ty 61 Origin, 62, 63 Vector representing moment 64 Moment 71 Origin 72, 73 Vector representing the direction of contact point and contact force 74 Circle representing direction of contact point and change in magnitude of contact force 75, 76 Tangent line from origin to circle 77 Angle of contact point Range of Direction Position 81 Rotary Shaft Hollow Portion 82 Lubricating Oil Passage 83 Lubricating Oil Passage 91a, 91b Lubricating Oil Passage 92a, 92b Lubricating Oil Passage 93a, 93b Lubricating Oil Passage

Claims (3)

[Claims] A sub-gear having the same number of teeth and modules as the main gear is supported adjacent to the main gear attached to the rotating shaft so as to be relatively rotatable with respect to the main gear, and the sub-gear is rotated between the main gear and the sub-gear. In a scissors gear mechanism in which an elastic body that applies a biasing force in the direction is interposed, when the center of rotation of the scissor gear is point O and the center of action of the force acting on the sub-gear from the elastic body is point A, the measurement is performed in the gear rotation direction. A scissors gear device provided with a lubricating oil supply passage for supplying lubricating oil to a contact surface between a sub gear and a main gear at or near a point P where an angle AOP is substantially 90 degrees. 2. A sub-gear having the same number of teeth and modules as the main gear is supported adjacent to the main gear attached to the rotating shaft so as to be rotatable relative to the main gear, and the sub-gear is rotated between the main gear and the sub-gear. In a scissors gear mechanism with an elastic body that applies a biasing force in the direction, a coordinate axis is set on the rotation axis of the scissor gear so that the scissors gear rotates in a left-handed screw direction, and a force acting on the sub gear from the elastic body A is the coordinate of the center point A on the coordinate axis, b is the coordinate of the center point B on the coordinate axis of the force acting on the sub-gear from the axis that rotatably supports the sub-gear, and b is the coordinate on the coordinate axis of the scissors gear. The coordinate on the coordinate axis of the acting center point C of the force input to the sub-gear through meshing on the tooth surface is c, while the scissors gear is rotating The distance from O to the point A rs, when the rg a distance from the rotation center O to the action center point C, and the pressure angle of the sub gear α, (-a + b) ( r g / r s) cosα ≧ b -c, the angle AOP (rad) measured in the direction of rotation of the scissors gear is given by A scissors gear device provided with a lubricating oil supply passage for supplying lubricating oil to a contact surface between the sub gear and the main gear at or near a point P satisfying the condition. 3. A scissors gear mechanism, wherein a circumferential groove is provided coaxially with a rotating shaft on a facing end face of a main gear or a sub gear, and a locking portion is projected from each of the main gear and the sub gear so as to face the circumferential groove. 3. The scissors gear device according to claim 1, wherein said circumferential groove has an elastic body for applying an urging force in a rotational direction with said locking portion acting.