JP4070266B2 - Gear train structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear train structure comprising a plurality of helical gears interlocking with a crankshaft gear mounted coaxially with an engine crankshaft.
[0002]
[Prior art]
In an automobile engine, a crankshaft gear mounted coaxially with the crankshaft is used to drive various external devices such as pumps, mixers and vacuum devices, or to drive engine-accompanying devices such as fuel injection valves. A gear train composed of a plurality of interlocking helical gears may be attached.
[0003]
[Problems to be solved by the invention]
In the gear train described above, among the plurality of helical gears, a helical gear that drives an external device or an engine associated device such as a fuel injection valve is, for example, an external device or an engine associated device such as opening / closing of a fuel injection valve. Depending on the operation, the applied driving torque may increase or decrease.
[0004]
For this reason, between the helical gears constituting the gear train and between the helical gears and the crankshaft gear, there is play between the helical gears and between the helical gears and the crankshaft gear. Backlash occurs during At this time, there is room for improvement in which the tooth surfaces of the helical gear and the crankshaft gear collide with each other to generate noise such as rattling noise.
[0005]
Therefore, in order to suppress abnormal noise generated between the helical gears and between the tooth surfaces of the crankshaft gear, a helical gear that constitutes the gear train is used as a helical gear that meshes with each other. It is possible to eliminate the play that exists between them.
[0006]
This scissor gear is provided with a pair of gears on the same axis, and these gears are urged by a spring or the like around the axis in the opposite directions. One gear of the pair of gears is used as a main gear for transmitting driving force, and the other gear is used as a sub gear for eliminating the play described above.
[0007]
The scissor gear can be free from backlash by eliminating play between the scissor gear and the helical gears that mesh with each other. However, in the above-described gear train, play occurs between the helical gears that are not meshed with the scissor gear, and noise is generated.
[0008]
That is, in the case of the scissor gear, it has to be disposed at each meshing position of the gear train, and a lot of scissor gears are required.
Therefore, an object of the present invention is to apply a drive acting on a helical gear only to a driven gear located at the end of the gear train in a gear train having a plurality of helical gears interlocking with the crankshaft gear. An object of the present invention is to provide a gear train structure that does not generate abnormal noise between helical gears that mesh with each other even when the torque increases or decreases.
[0009]
[Means for Solving the Problems]
In the gear train structure of the present invention according to claim 1 for solving the above-mentioned problems and achieving the object, an engine associated device which is located at an end of the gear train and is to be operated in conjunction with the crankshaft gear is provided. A driven gear movable in the axial direction of the driving shaft, biasing means for applying a biasing force to the driven gear in a direction opposite to a thrust force generated in the driven gear in the gear train, and the crankshaft An idler gear that is provided between the gear and the driven gear and transmits the rotation of the crankshaft to the driven gear and is movable in an axial direction, and the idler gear is transmitted from the driven gear. By receiving the urging force and transmitting it to the helical gear on the crankshaft gear side, the tooth surface of the idler gear is brought into close contact with the tooth surface of the helical gear on the other side.
[0010]
Therefore, backlash generated between the plurality of helical gears and the crankshaft gear is reduced. Further, the biasing means, since the thrust force generated in the driven gear for generating a biasing force opposite to bias the driven gear in the opposite direction to the thrust force. For this reason, even in a gear train having a large driving reaction force, the urging means does not need a large urging force exceeding the driving reaction force and only needs to have a relatively small urging force.
[0011]
In the gear train structure according to the second aspect of the present invention, since the urging means urges the driven gear via the thrust plate, friction generated between the urging means and the driven gear is reduced. It becomes possible.
According to a third aspect of the present invention, the idler gear can move in the axial direction when the range in which the idler gear can move is changed from a state where the tooth surfaces of the crankshaft gear and the idler gear do not contact each other. is set to the first moving amount is dimensioned, movable range of the driven gear, the driven gear when the tooth surface before Symbol idler gear and the driven gear is changed to a state of being in contact from a state which is not in contact The second movement amount is set to a dimension that is movable in the axial direction and that is larger than the first movement amount .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
As shown in FIGS. 1 and 2, the gear train structure 1 is attached to an engine 2 such as an automobile, and a crankshaft gear 4 including a helical gear attached coaxially to the crankshaft 3, and the crankshaft gear. Two helical gears 5 and 6 meshing with and interlocking with 4 and an urging means 7 for urging the helical gear 6 located at the end of the gear train of the helical gears 5 and 6; It has.
[0013]
In the present embodiment, the helical gear 5 that meshes with the crankshaft gear 4 among the plurality of helical gears 5 and 6 is called an idler gear, and is meshed with the idler gear 5 and positioned at the end of the gear train. The helical gear 6 is called an injection pump gear as a driven gear.
[0014]
The injection pump gear 6 is connected to a fuel injection pump 8 as an example of an accompanying device of the engine. The fuel injection pump 8 is a fuel injection valve (not shown) so as to inject fuel to each cylinder unit 9 at a desired timing by the rotational driving force transmitted from the crankshaft gear 4 via the injection pump gear 6. Open and close.
[0015]
The idler gear 5 is rotatably provided on the central shaft 11 as shown in FIG. The central shaft 11 is provided substantially parallel to the crankshaft 3 and is fixed to the casing 10 of the engine 2 or the like.
[0016]
The idler gear 5 is sandwiched between the first stopper plate 12 and the second stopper plate 13 fixed to the central shaft 11 so as to be movable in the axial direction by the distance S1. . The stop plates 12 and 13 hold the idler gear 5 so as to be movable by an interval S1 along the axial direction of the central shaft 11 and are positioned with respect to the engine 2.
[0017]
The interval S1 is determined by moving the idler gear 5 along the central axis 11 from a state where play is generated between the tooth surfaces when the crankshaft gear 4 and the idler gear 5 are assembled. And the idler gear 5 are close to each other so that no backlash occurs between the crankshaft gear 4 and the idler gear 5.
[0018]
With this configuration, the crankshaft gear 4 is subjected to a force (thrust force) T1 directed in the direction along the crankshaft 3 and the central shaft 11 by the rotational driving force transmitted from the crankshaft 3. Will be.
[0019]
The injection pump gear 6 is provided at the end of the pump shaft 14 connected to the fuel injection pump 8. The pump shaft 14 is rotatable with respect to the casing 10 of the engine 2 and is provided substantially parallel to the crankshaft 3 and the central shaft 11.
[0020]
The injection pump gear 6 rotates together with the pump shaft 14 about the axis around the pump shaft 14. The injection pump gear 6 is fixed by bolts. In the casing 10, a first presser plate 15 integrally formed with the pump shaft 14 is disposed. The pump shaft 14 is positioned so as to be movable with respect to the second pressing plate 16.
[0021]
The second presser plate 16 is provided coaxially with the injection pump gear 6 and is rotatable with respect to the pump shaft 14. The second presser plate 16 is provided in a state that it can move along the axial direction of the pump shaft 14 together with the injection pump gear 6 by an interval S2.
[0022]
The second presser plate 16 reduces the friction generated between the second presser plate 16 and the injection pump gear 6 even when it is pressed toward the injection pump gear 6 by the following compression spring 17 that functions as the urging means 7, thereby reducing the injection pump gear 6. The metal is made of a metal having a relatively small coefficient of friction so as not to hinder the rotation.
[0023]
The distance S2 is not greater than the interval S1. That is, when the idler gear 5 and the injection pump gear 6 are assembled, the injection pump gear 6 is moved along the axial direction of the pump shaft 14 from the state where play is generated between the tooth surfaces of the idler gear 5 and the injection pump gear 6. When the tooth surfaces of the pump gear 6 are brought into close contact with each other, the dimension is such that no backlash occurs between the idler gear 5 and the injection pump gear 6, and the idler gear 5 is located between the idler gear 5 and the crankshaft gear 4. Even if it moves on the central shaft 11 by an interval S1 that does not cause backlash, the interval is such that the movement of the injection pump gear 6 can follow.
[0024]
With this configuration, the idler gear 5 and the injection pump gear 6 are moved in the direction along the axial direction of the central shaft 11 and the pump shaft 14 by the rotational driving force transmitted from the crankshaft 3 to the idler gear 5. Directed forces (thrust forces) T3 and T4 act respectively.
[0025]
The urging means 7 is constituted by a compression spring 17 which is provided between the casing 10 of the engine 2 and the second presser plate 16 and urges the injection pump gear 6 in the direction opposite to the thrust force T4. . The urging force of the compression spring 17 is smaller than the thrust force T4.
[0026]
According to the above-described configuration, the compression spring 17 causes the injection pump gear 6 as an example of the driven gear positioned at the end of the gear train structure 1 to have a force smaller than the thrust force T4 in the direction opposite to the thrust force T4. It will be energized at.
[0027]
In this way, the compression spring 17 biases the injection pump gear 6 in the direction of the arrow F1 shown in FIG. 2 against the thrust force T4.
[0028]
Further, the tooth surface of the injection pump gear 6 is brought into close contact with the tooth surface of the idler gear 5 by the biasing force of the compression spring 17. Since the interval S2 is formed larger than the interval S1, when the tooth surface of the injection pump gear 6 is brought into pressure contact with the tooth surface of the idler gear 5, the injection pump gear 6 and the idler gear 5 are integrated into the illustrated state. It is energized along the arrow F3. Then, the tooth surface of the crankshaft gear 4 is pressed against the tooth surface of the idler gear 5.
[0029]
As described above, when the teeth of the injection pump gear 6 and the idler gear 5 are engaged with each other, the compression spring 17 is moved when the meshing relationship shifts from the tooth meshed with the surface pressure to the next tooth. The low surface pressure state that occurs temporarily is eliminated. In other words, the compression spring 17 presses the tooth surfaces together to eliminate play between the injection pump gear 6 and the idler gear 5 and also eliminate play between the idler gear 5 and the crankshaft gear 4.
[0030]
Therefore, even if the drive torque acting on the injection pump gear 6 is increased or decreased by opening / closing the fuel injection valve, the backlash generated between the helical gears 4, 5 and 6 constituting the gear train is reduced. And no abnormal noise is generated between the helical gears 4, 5, 6 that mesh with each other.
[0031]
Further, since the second presser plate 16 is constituted by a thrust plate that suppresses friction between the second presser plate 16 and the injection pump gear 6, friction between the compression spring 17 and the injection pump gear 6 is reduced. For this reason, the lifetime of the injection pump gear 6 can be extended.
[0032]
As shown in FIG. 3, the compression spring 17 may be provided between the injection pump gear 6 and an outer casing 18 that is located outside the casing 10 and surrounds the injection pump gear 6 from the outside. . The end portion 14a of the pump shaft 14 in this case is integrally provided with a protruding portion 19 that penetrates the injection pump gear 6 and the outer casing 18 and has an enlarged outer diameter at its end.
[0033]
The compression spring 17 is provided between the protrusion 19 and the outer casing 18, and urges the injection pump gear 6 along the arrow F1 against the thrust force T4. Also in this case, as in the case shown in FIG. 2 described above, backlash is reduced by eliminating play between the helical gears 4, 5, and 6.
[0034]
FIG. 4 shows a second embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.
In this embodiment, since the meshing between the injection pump gear 6 and the idler gear 5 is opposite to that in the first embodiment described above, the thrust force T4a acting on the injection pump gear 6 is also the above-mentioned. The direction is opposite to the thrust force T4.
[0035]
As shown in FIG. 4, the gear train structure 20 of the present embodiment is provided with a biasing means 21 between the injection pump gear 6 and the outer casing 18, and this biasing means 21 is located on the outer casing 18 side. The compression spring 22 is disposed on the injection pump 6 side, the thrust bearing 23 is disposed on the injection pump 6 side, and the support plate 24 is provided between the compression spring 22 and the thrust bearing 23.
[0036]
The pump shaft 14 is provided with a bobbin 25 and is rotatable with respect to the casing 10. The bobbin 25 has flanges 26 and 27 at both ends thereof. The bobbin 25 is formed so that the casing 10 is positioned between the flanges 26 and 27 .
[0037]
With this configuration, the injection pump gear 6 is movable along the axial direction of the pump shaft 14 by the interval S2. Further, the idler gear 5 is fitted with no gap between the stop plates 12 and 13.
[0038]
According to the configuration described above, the compression spring 22 urges the injection pump gear 6 along the arrow F1a in the figure against the thrust force T4a via the support plate 24 and the thrust bearing 23. Become.
[0039]
Thereby, the teeth of the injection pump gear 6 and the idler gear 5 are in close contact with each other. Further, the injection pump gear 6 is moved in the F1a direction by the urging force of the compression spring 22 and rotates the idler gear 5 until the idler gear 5 and the crankshaft gear 4 are in close contact with each other.
Accordingly, as in the first embodiment described above, the play between the helical gears 4, 5, and 6 is eliminated, and the backlash is reduced. For this reason, even if the drive torque acting on the injection pump gear 6 is increased or decreased by opening or closing the fuel injection valve or the like, no noise is generated between the helical gears 4, 5 and 6.
[0040]
Further, since the thrust bearing 23 hardly generates friction between the support plate 24 and the injection pump gear 6, the shortening of the life of the injection pump gear 6 is further suppressed.
[0041]
5 and 6 show a fourth embodiment, and the same components as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.
In this embodiment as well, as in the second embodiment described above, the meshing between the injection pump gear 6 and the idler gear 5 is opposite to that in the first embodiment described above, and therefore the injection pump gear. The thrust force T4a acting on 6 is also opposite to the thrust force T4.
[0042]
In FIG. 5, magnets 34a and 34b having different poles are attached to the casing 10 and the injection pump gear 6 so as to face each other. In FIG. 6, magnets 33, 33 having the same pole are attached to the outer casing 18 and the injection pump gear 6 so as to face each other.
[0043]
In the gear train structure 35 of the present embodiment, the biasing means 7 uses magnets 33 and 33 having the same poles (shown in FIG. 6) or magnets 34a and 34b having different poles (shown in FIG. 5) and the same. The injection pump gear 6 is urged along the arrow F1a in the figure against the thrust force T4a by the repulsive force of the pole magnets 33, 33 or the attractive force of the magnets 34a, 34b of different poles.
[0044]
Also in this embodiment, since the backlash is reduced by eliminating play between the helical gears 4, 5, 6, the driving torque acting on the injection pump gear 6 is increased or decreased by opening / closing the fuel injection valve or the like. However, no abnormal noise is generated between the helical gears 4, 5, 6. Further, since the magnets 33, 34a, 34b do not contact each other, they are not worn.
[0045]
The present invention is not limited to the first to third embodiments. As shown in FIG. 7, the engine is used to drive the external devices 40 such as various pumps, mixers, and vacuums. 2 may be used as a gear train structure 41 that is connected to the second crankshaft 3 and transmits a driving force from the engine 2 to the external device 40.
[0046]
Further, the driven gear in the gear train structure of the present invention is not limited to the injection pump gear 6 used for driving the fuel injection pump 8 described above, and it is used to drive various associated devices attached to the engine. It can be a gear.
[0047]
Further, a plurality of idler gears 5 provided between the crankshaft gear 4 and the driven gear may be provided as necessary. In this case, the axial displacement of the idler gear 5 located on the crankshaft 3 side is further suppressed. It becomes possible to do.
[0048]
【The invention's effect】
According to the first and third aspects of the present invention, backlash generated between the crankshaft gear , the idler gear , and the driven gear, which are meshed with each other , can be reduced. Even if the driving torque acting on one helical gear increases or decreases, no noise is generated between the helical gears that mesh with each other.
[0049]
According to the second aspect of the present invention, in addition to the effect of the first aspect, the friction generated between the urging means and the driven gear is reduced, so that the shortening of the life of the driven gear is further suppressed. Can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an engine using a gear train structure according to a first embodiment of the present invention.
FIG. 2 is a diagram schematically showing meshing of helical gears along the line ii-ii shown in FIG. 1;
FIG. 3 is a side view showing a modification of the biasing means of the embodiment in a partial cross section.
FIG. 4 is a sectional view showing a gear train structure according to a second embodiment of the present invention.
FIG. 5 is a side view showing a gear train structure according to a third embodiment of the present invention in a partial cross section.
FIG. 6 is a side view showing, in partial cross section, a modification of the biasing means of the third embodiment of the present invention.
FIG. 7 is a side view showing a modified example of an engine having a gear train structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gear train structure 2 ... Engine 3 ... Crankshaft 4 ... Crankshaft gear 5 ... Idler gear (helical gear)
6 ... Injection pump gear (driven gear)
7 ... Energizing means 8 ... Fuel injection pump (engine accompanying device)
16 ... Second presser plate (thrust plate)
T4 ... Thrust force

Claims (3)

In a gear train composed of a plurality of helical gears interlocking with a crankshaft gear mounted coaxially with the crankshaft,
A driven gear movable at an axial direction for driving an engine-accompanying device to be operated in conjunction with the crankshaft gear located at an end of the gear train;
A biasing means for imparting a biasing force to the driven gear in a direction opposite to a direction of a thrust force generated in the driven gear in the gear train;
An idler gear that is provided between the crankshaft gear and the driven gear and transmits the rotation of the crankshaft to the driven gear, and is movable in the axial direction;
The idler gear receives the urging force transmitted from the driven gear and transmits the biasing force to the helical gear on the crankshaft gear side so that the tooth surface of the idler gear is the tooth of the helical gear on the other side. A gear train structure characterized by being in close contact with the surface.   The gear train structure according to claim 1, wherein the biasing means applies a biasing force to the driven gear via a thrust plate disposed coaxially with the driven gear. The movable range of the idler gear is set to a first movement amount that is a dimension in which the idler gear can move in the axial direction when the crankshaft gear and the tooth surface of the idler gear are changed from a non-contact state to a contact state. And
The movable range of the driven gear is a dimension that allows the driven gear to move in the axial direction when the idler gear and the tooth surface of the driven gear are changed from a non-contact state to a contact state, and The gear train structure according to claim 1, wherein the gear train structure is set to be a second movement amount having a dimension larger than the first movement amount .

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