JP2007232162A - Idle gear support structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an idle gear support structure, setting substantially constant thrust clearance without any increase in the number of parts. <P>SOLUTION: This idle gear support structure includes: a shaft 20 having shaft end faces 22, 23 at the projection side and the base side; an idle gear 30; a spacer 14 between a cylinder block 11 and the shaft 20 , which has at least one of a projection side thrust bearing 40 and a base side thrust bearing 41; and a thrust plate 38 located on the projection side of the shaft 20. The projection side shaft end face 22 is abutted on the face of one of the projection side thrust bearing 40 and the thrust plate 38, and the projection side end face 35 is adjacent to the above face. The base side shaft end face 23 is abutted on the face of one of the base side thrust bearing 41 and the spacer 14, and the base side end face 35 is adjacent to the above face. The thrust clearance of the idle gear 30 is defined by the respective one faces at the projection side and the base side and one face at the base side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an idle gear support structure in an internal combustion engine such as an engine, and more particularly to an idle gear support structure including a thrust bearing that supports a load in the thrust direction of the idle gear.

As a conventional idle gear support structure, for example, there is an idle gear support structure shown in FIG.
In this idle gear support structure, the shaft 70 is fixed to the cylinder block 61 via fixing bolts 69, and the idle gear 80 is rotatably supported on the outer peripheral portion 71 of the shaft 70 via a radial bearing 78. Yes.
The idle gear 80 is a “helical gear” and has a tooth surface 82 that is inclined with respect to the rotational axis.
A thrust plate 88 is brought into contact with the projecting side shaft end surface 72 of the shaft 70, and the thrust plate 88 is fixed to the shaft 70 via a fixing bolt 69.

A thrust side thrust bearing 90 is interposed between the thrust plate 88 and the idle gear 80.
A protrusion 70 a is formed on the base side of the shaft 70 so as to face the base-side end face 85 of the idle gear 80, and a base-side thrust bearing 91 is interposed between the protrusion 70 a and the idle gear 80. .
The protrusion-side thrust bearing 90 has a perforated disk shape and includes a through hole 90b that allows the shaft 70 to pass therethrough and a thrust end surface 90a.
In addition, a lubricating oil passage 76 reaching the outer peripheral portion 71 is formed in the shaft 70, and a configuration for lubricating the radial bearing 78 and the thrust bearings 90 and 91 with the lubricating oil is adopted.

By the way, since the idle gear 80 is a “helical gear”, a load in the thrust direction acts on the idle gear 80 in addition to a load in the radial direction.
When the thrust load on the idle gear 80 acts excessively, the movement of the idle gear 80 being inclined with respect to the rotation axis increases, which may cause wear and seizure.
The protruding side thrust bearing 90 and the base side thrust bearing 91 are provided to prevent wear and seizure based on the load in the thrust direction.
In this case, it is important to set a clearance (denoted as “thrust clearance” for convenience of explanation) between the protruding side end surface 84, the base side end surface 85, and the thrust bearings 90 and 91 in the idle gear 80.
Incidentally, when the thrust clearance is set too narrow, the formation of an oil film by the lubricating oil becomes insufficient, and when the thrust clearance is set too wide, the tilting movement of the idle gear 80 increases.

Moreover, as the same kind of technology, for example, the idle gear support structure disclosed in Patent Document 1 can be cited.
This technique employs a configuration in which an elastic washer is interposed between at least one of the shaft flange and the thrust washer or between the thrust plate and the thrust washer.
Japanese Utility Model Publication No. 63-24448

However, the conventional technique shown in FIG. 4 has a problem that the projecting-side thrust bearing 90 and the base-side thrust bearing 91 are included as elements that influence the setting of the thrust clearance.
This point will be described in detail. The thrust clearance in the prior art is the dimension in the thrust direction on the shaft 70 side of the idle gear 80 (distance between the base-side end face 85 and the protruding-side end face 84), each thrust bearing 90, 91 in the thrust direction dimension (thickness) and the dimension in the thrust direction of the outer peripheral portion 71 of the shaft 70 (the distance between the bearing 90 side end surface of the thrust plate 88 and the bearing 91 side end surface of the projection 70a). It is determined.
This means that the accumulated dimensional tolerance of the idle gear 80 and each of the thrust bearings 90 and 91 is reflected as a variation in clearance. As a result, the thrust clearance may be too narrow or too wide. is there.

  On the other hand, the technique disclosed in Patent Document 1 is an excellent technique for solving wear and seizure problems from the viewpoint different from the thrust clearance by interposing an elastic washer. However, a part called an elastic washer must be added. There is a fact that it must be.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an idle gear support structure capable of setting a substantially constant thrust clearance without increasing the number of parts.

In order to achieve the above object, the present invention provides a shaft having a base side fixed to a cylinder block and having a shaft end surface perpendicular to the thrust direction on the protruding side and the base side, and an idle that is rotatably held on the outer periphery of the shaft. An idle gear support structure having at least one of a gear, a projecting side thrust bearing slidably contactable with a projecting side end surface of the idle gear, and a base side thrust bearing slidably contacted with a base side end surface, the cylinder block and the A spacer interposed between the shafts and a thrust plate located on the projecting side of the shaft are provided, and the shaft end surface on the projecting side is in contact with one surface of the projecting side thrust bearing or thrust plate, and the projecting of the idle gear The projecting side thrust bearing has a side end surface out of one surface of the projecting side thrust bearing or thrust plate. Adjacent to the one surface to be abutted, the shaft end surface on the base side abuts on one surface of the base side thrust bearing or spacer, and the base side end surface of the idle gear is one of the base side thrust bearing or spacer. Among the surfaces, the idle gear is adjacent to the one surface that comes into contact with the base-side thrust bearing, and includes one surface of the protrusion-side thrust bearing or thrust plate and one surface of the base-side thrust bearing or spacer. The clearance in the thrust direction is defined.
The “base side” here refers to the direction on the cylinder block side as viewed from the shaft, and the “projection side” refers to the direction on the thrust plate side as viewed from the shaft.

According to the present invention, the protruding shaft end surface is in contact with one surface of the protruding thrust bearing or thrust plate, and the protruding end surface of the idle gear is one of the surfaces of the protruding thrust bearing or thrust plate, Adjacent to one surface abutting against the protruding thrust bearing.
The shaft end surface on the base side is in contact with one surface of the base side thrust bearing or spacer, and the base side end surface of the idle gear is in contact with the base side thrust bearing of one surface of the base side thrust bearing or spacer. Adjacent to one face touched.
For this reason, the clearance in the thrust direction of the idle gear is defined by one surface of the protruding-side thrust bearing or thrust plate and one surface of the base-side thrust bearing or spacer, and in setting the thrust clearance, at least the thrust bearing Thrust direction dimension (thickness) is not required.
In addition, the meaning of "a face and a face adjoining" here means that each face is in contact with each other and in an approached state. Means that there are no inclusions

In the present invention, in the above-described idle gear support structure, the idle gear may be a helical gear.
In this case, since the idle gear is a helical gear, a load in the thrust direction surely acts on the idle gear.
For this reason, the setting of the thrust clearance in consideration of the dimension in the thrust direction of the idle gear and the dimension in the thrust direction on the outer periphery of the shaft realizes an appropriate clearance that is neither too narrow nor too wide. Abrasion and seizure are prevented more remarkably.

In the present invention, in the idle gear support structure described above, the spacer may be formed integrally with a gear case that covers the idle gear.
In this case, the number of parts in the idle gear support structure can be suppressed by integrating the spacer and the gear case.

In the present invention, in the idle gear support structure described above, the distance between the protruding side end surface of the idle gear and the base side end surface is between the protruding side shaft end surface and the base side shaft end surface of the shaft. It is preferable to set the distance to less than.
In this case, the thrust clearance is ensured by setting the distance between the projecting side end surface and the base side end surface of the idle gear to be less than the distance between the projecting side shaft end surface and the base side shaft end surface of the shaft. The

  According to the present invention, it is possible to provide an idle gear support structure capable of setting a substantially constant thrust clearance without increasing the number of parts.

Hereinafter, an idle gear support structure according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an idle gear support structure according to the first embodiment.
As shown in FIG. 1, the idle gear support structure of the first embodiment includes an engine cylinder block 11, a spacer 14, a shaft 20, an idle gear 30, a thrust plate 38, a fixing bolt 19, a protruding side thrust bearing 40, The base side thrust bearing 41 and the radial bearing 28 are the main components.

The cylinder block 11 is a known cylinder block, and a positioning hole 12 of the shaft 20 and a screw hole 13 for fastening the fixing bolt 19 are formed on the side surface of the cylinder block 11.
The axes of the positioning hole 12 and the screw hole 13 are parallel.
A spacer 14 with a gear case 15 is in contact with the side surface of the cylinder block 11.
The spacer 14 according to this embodiment is a member in which a gear case 15 that covers the periphery of the idle gear 30 is integrally formed.
The spacer 14 has an insertion hole 16 through which the positioning shaft portion 24 of the shaft 20 is inserted and an insertion hole 17 for the fixing bolt 19. The spacer 14 is connected to the shaft 20 and the thrust plate 38 via the fixing bolt 19. The cylinder block 11 is fixed.
Note that a vertical protrusion-side spacer end face 14a is formed on the protrusion side of the spacer 14 (left side in FIG. 1).

The shaft 20 is a shaft member that holds the idle gear 30, and an outer peripheral portion 21 to which a radial bearing 28 for holding the idle gear 30 is mounted is formed.
A protruding side shaft end surface 22 perpendicular to the thrust direction is formed on the protruding side of the shaft 20, and a base side shaft end surface 23 perpendicular to the thrust direction is formed on the base side (right side in FIG. 1) of the shaft 20. Is formed.
A positioning shaft portion 24 corresponding to the positioning hole 12 on the cylinder block 11 side is provided on the base side shaft end surface 23 toward the cylinder block 11 side.
After inserting the spacer 14 into the positioning shaft portion 24 and then inserting the positioning shaft portion 24 into the positioning hole 12 of the cylinder block 11, the position of the shaft 20 relative to the cylinder block 11 (the vertical position in FIG. 1). Stipulate.
The depth of the positioning hole 12 in the cylinder block 11 is set to such a depth that the tip of the positioning shaft portion 24 does not hit the bottom of the positioning hole 12.

Inside the shaft 20, a bolt through hole 25 for the fixing bolt 19 penetrating the protruding side shaft end surface 22 and the base side shaft end surface 23 is formed.
The axes of the positioning shaft portion 24 and the bolt through hole 25 are parallel to each other and have a relationship that coincides with the axis of the positioning hole 12 and the screw hole 13 in the cylinder block 11.
Inside the shaft 20, there are provided a through hole 26 formed along the axis of the center of the positioning shaft portion 24 and a communication hole 27 extending from the through hole 26 to the outer peripheral portion 21.
The through hole 26 and the communication hole 27 constitute a lubricating oil passage, and serve as a passage for guiding the lubricating oil from the cylinder block 11 side to the thrust bearings 40 and 41 (the lubricating oil passage in the cylinder block 11 is not shown). .
An idle gear 30 is rotatably held on the outer peripheral portion 21 of the shaft 20 via a radial bearing 28.

The idle gear 30 is a gear for transmitting torque of a crankshaft (not shown) in the engine to various devices.
The idle gear 30 of this embodiment is a “helical gear”, and a tooth surface 32 that meshes with another gear is formed on the outer peripheral portion of the idle gear 30.
On the projecting side of the shaft body portion 33 in the idle gear 30, a projecting side end surface 34 perpendicular to the rotational axis of the idle gear 30 is formed, and on the base side, a base side end surface 35 parallel to the projecting side end surface 34 is formed. Is formed.
The dimension between the projecting side end surface 34 and the base side end surface 35 of the idle gear 30 (referred to as “gear side thrust dimension” for convenience) is between the projecting side shaft end surface 22 and the base side shaft end surface 23 of the shaft 20. Is set slightly shorter than the dimension (for convenience, it is referred to as “shaft side thrust dimension”).
The difference between the gear-side thrust dimension and the shaft-side thrust dimension corresponds to the clearance in the thrust direction of the idle gear 30 (“thrust clearance” for convenience).

A thrust plate 38 is located on the protruding side of the shaft 20, and an insertion hole 39 through which the fixing bolt 19 is inserted is formed in the thrust plate 38.
The axial force of the fixing bolt 19 acts as an urging force that presses the thrust plate 38 toward the cylinder block 11.
A protruding side thrust bearing 40 is interposed between the thrust plate 38 and the shaft 20, and a base side thrust bearing 41 is interposed between the shaft 20 and the spacer 14.
The protrusion side thrust bearing 40 and the base side thrust bearing 41 are both disk-shaped slide bearings.

Each of the thrust bearings 40 and 41 is set to have a larger diameter than the protruding side shaft end surface 22 and the base side shaft end surface 23 of the shaft 20.
In other words, it can be said that the protruding shaft end surface 22 and the base shaft end surface 23 are smaller in diameter than the thrust bearings 40 and 41.
In this embodiment, the diameter is set so as to cover the protruding side end surface 34 and the base side end surface 35 of the idle gear 30 when the thrust bearings 40 and 41 are mounted.

The surface of each thrust bearing 40, 41 constitutes thrust end surface 40a, 41a, and a number of recesses (not shown) capable of retaining lubricating oil are formed on the flat surface.
The thrust end surface 40 a of the protruding side thrust bearing 40 is in contact with the protruding side shaft end surface 22 of the shaft 20.
In the protruding thrust bearing 40, the portion of the shaft 20 that protrudes from the protruding shaft end surface 22 faces the protruding side end surface 34 of the idle gear 30, and corresponds to the portion that is in sliding contact with the protruding side end surface 34 of the idle gear 30.
The protrusion-side thrust bearing 40 has a bolt insertion hole 40 b through which the fixing bolt 19 is inserted.
On the other hand, the base side thrust bearing 41 has the same dimensions as the protruding side thrust bearing 40, and the thrust end surface 41 a of the base side thrust bearing 41 is in contact with the base side shaft end surface 23.
In the base-side thrust bearing 41, the portion of the shaft 20 that protrudes from the base-side shaft end surface 23 corresponds to a portion that faces the base-side end surface 35 of the idle gear 30.
In addition, the base side thrust bearing 41 is formed with a through hole 41c through which the positioning shaft portion 24 is inserted, in addition to the bolt insertion hole 41b.

As described above, the thrust-side thrust bearing 40 and the base-side thrust bearing 41 are in contact with the shaft 20 to define the position in the thrust direction.
Therefore, the dimensions of the thrust end face 40a in the protruding side thrust bearing 40 and the thrust end face 41a in the base side thrust bearing 41 coincide with the shaft side thrust dimension.
That is, it can be said that the thrust end faces 40a and 41a define the clearance of the idle gear 30 in the thrust direction.
Even if the thrust clearance varies due to tolerances, the tolerance that causes variations in the thrust clearance does not include the dimensions of the thrust bearings 40 and 41 in the thrust direction, but only the gear-side thrust dimension relative to the shaft-side thrust dimension.
Therefore, even if the clearance varies due to the tolerance of the gear side thrust dimension, the degree of the variation in the clearance is significantly suppressed as compared with the conventional case.
The idle gear 30 that receives the thrust force maintains a stable rotation by setting an appropriate clearance.

The idle gear support structure according to the first embodiment has the following effects.
(1) Since the thrust end surfaces 40a and 41a of the protruding side thrust bearing 40 and the base side thrust bearing 41 are surfaces facing the protruding side end surface 34 and the base side end surface 35 of the idle gear 30, the protruding side is used in setting the thrust clearance. The dimensions (thicknesses) of the thrust bearing 40 and the base side thrust bearing 41 in the thrust direction are not required. For this reason, a substantially constant thrust clearance can be set without increasing the number of parts.
(2) Since the thrust end surface 41a of the base side thrust bearing 41 is in sliding contact with the base side end surface 35 of the idle gear 30, the thrust clearance is the gear side thrust dimension (the distance between the base side end surface 35 and the protruding side end surface 34). And only the shaft-side thrust dimension (the distance between the thrust end surface 40a of the protruding-side thrust bearing 40 and the thrust end surface 41a of the base-side thrust bearing 41) need only be considered.

(3) Since the idle gear 30 is a helical gear, the load in the thrust direction acts on the idle gear 30 with certainty, but the setting of the thrust clearance in consideration of the gear side thrust dimension and the shaft side thrust dimension is as follows: Since an appropriate clearance that is neither too narrow nor too wide is realized, wear and seizure of the shaft 20, the thrust bearings 40 and 41, and the idle gear 30 due to a load in the thrust direction are more significantly prevented.
(4) By setting the distance between the projecting side end surface 22 of the shaft 20 and the base side end surface 23 to be less than the distance between the thrust end surfaces 40a and 41a of the projecting side thrust bearing 40 and the base side thrust bearing 41, Ensures thrust clearance.
(5) Since the spacer 14 and the gear case 15 are integrated, the number of parts in the idle gear support structure can be suppressed.

(Second Embodiment)
Next, an idle gear support structure according to a second embodiment will be described.
The idle gear support structure of this embodiment is an example that does not include the spacer in the first embodiment.
Therefore, in this embodiment, the configuration excluding the cylinder block is basically the same as that of the first embodiment, and the same configuration is denoted by the same reference numerals used in the first embodiment, and the description thereof is omitted. Incorporate.
FIG. 2 is a longitudinal sectional view showing an idle gear support structure according to the second embodiment.

As shown in FIG. 2, in the idle gear support structure according to the second embodiment, the cylinder block 51 has a bulging portion 52 that bulges sideways.
The bulging portion 52 is formed with a vertical bulging portion end surface 52 a, and the bulging portion end surface 52 a is formed with a positioning hole 53 corresponding to the positioning shaft portion 24 of the shaft 20.
A screw hole 54 for fastening the fixing bolt 19 is formed in the vicinity of the positioning hole 53, and the axes of the positioning hole 53 and the screw hole 54 are parallel to each other.
The axes of the positioning hole 53 and the screw hole 54 are parallel to each other, and have a relationship that coincides with the axis of the positioning shaft portion 24 and the bolt through hole 25 in the shaft 20.
The configuration excluding the cylinder block 51, that is, the shaft 20, the idle gear 30, the protruding-side thrust bearing 40, the base-side thrust bearing 41, the radial bearing 28, and the fixing bolt 19 are the same as those described in the first embodiment. Are the same.

According to the idle gear support structure according to the second embodiment, the same operational effects as the operational effects (1) to (4) of the first embodiment are achieved.
Furthermore, in this embodiment, since the spacer is omitted, the number of parts in the idle gear support structure can be suppressed.

(Third embodiment)
Next, an idle gear support structure according to a third embodiment will be described.
The third embodiment is an example in which the base side thrust bearing in the idle gear support structure is omitted.
Therefore, in this embodiment, except for the point that the base side thrust bearing does not exist, the other configurations are basically the same as those of the first embodiment, and the reference numerals used in the first embodiment are used in common. The explanation is incorporated.
FIG. 3 is a longitudinal sectional view showing an idle gear support structure according to the third embodiment.

As shown in FIG. 3, the shaft 20 is in direct contact with the spacer 14 with the gear case 15.
The protruding end face of the spacer 14 is a protruding spacer end face 14 a formed on a vertical surface, and the base end face 35 of the idle gear 30 faces the protruding spacer end face 14 a of the spacer 14.
The protruding side spacer end surface 14a and the base side end surface 35 of the idle gear 30 are in contact with each other or have a clearance in the thrust direction.
The thrust clearance of this embodiment is defined by the difference between the dimension between the thrust end face 40a and the protrusion-side spacer end face 14a in the protrusion-side thrust bearing 40 and the gear-side thrust dimension.

The protrusion-side thrust bearing 40 and the spacer 14 are in contact with the shaft 20 so that the positions in the thrust direction are defined.
Accordingly, the dimensions of the thrust end surface 40a of the protruding side thrust bearing 40 and the protruding side spacer end surface 14a of the spacer coincide with the shaft side thrust dimension.
That is, the protrusion-side spacer end surface 14a of the spacer 14 plays the same role as the thrust end surface 41a of the base-side thrust bearing 41 in the first embodiment in setting the thrust clearance, and is idle together with the thrust end surface 40a of the protrusion-side thrust bearing 40. It can also be said that the clearance in the thrust direction of the gear 30 is defined.

According to the idle gear support structure according to the third embodiment, the same operational effects as the operational effects (1) to (4) of the first embodiment are achieved.
Furthermore, in this embodiment, since the base side thrust bearing is omitted, the number of parts in the idle gear support structure can be suppressed.

  In addition, this invention is not limited to said 1st-3rd embodiment, A various change is possible within the range of the meaning of invention, For example, you may change as follows.

In the first to third embodiments, the spacer and the gear case are integrated. However, it is not essential to integrate the spacer and the gear case, and the purpose is to prevent the spacer and the gear case from being independent parts. is not.
In the third embodiment, an example in which the base side thrust bearing is omitted is shown. However, for example, a base side thrust bearing may be used, and the protruding side thrust bearing may be omitted. It is sufficient that at least one of the bearings is used.

It is a longitudinal cross-sectional view which shows the idle gear support structure which concerns on 1st Embodiment. It is a longitudinal cross-sectional view which shows the idle gear support structure which concerns on 2nd Embodiment. It is a longitudinal cross-sectional view which shows the idle gear support structure which concerns on 3rd Embodiment. It is a longitudinal cross-sectional view which shows the conventional idle gear support structure.

Explanation of symbols

11, 51, 61 Cylinder block 14 Spacer 14a Projection side spacer end surface 15 Gear case 19 Fixing bolt 20, 70 Shaft 21 Outer peripheral portion 22 Projection side shaft end surface 23 Base side shaft end surface 28, 78 Radial bearing 30, 80 Idle gear 33 Shaft Portions 34, 84 Protruding side end surfaces 35, 85 Base side end surfaces 38, 88 Thrust plates 40, 90 Protruding side thrust bearings 40a, 90a Thrust end surfaces (protruding side thrust bearings)
41, 91 Base side thrust bearing 41a Thrust end face (base side thrust bearing)
52a Swelling end face 70a Projection 76 Lubricating oil passage

Claims (4)

A shaft having a base side fixed to the cylinder block and having a shaft end surface perpendicular to the thrust direction on the projecting side and the base side, an idle gear rotatably held on the outer periphery of the shaft, and a projecting side end surface of the idle gear; An idle gear support structure having at least one of a sliding-side protruding thrust bearing and a base-side end face that is slidable and a base-side thrust bearing that is slidable,
A spacer interposed between the cylinder block and the shaft, and a thrust plate located on the protruding side of the shaft;
The shaft end surface on the protruding side is in contact with one surface of the protruding side thrust bearing or thrust plate,
The projecting side end surface of the idle gear is adjacent to the one surface of the projecting side thrust bearing or the thrust plate, which is in contact with the projecting side thrust bearing,
The shaft end surface on the base side is in contact with one surface of the base side thrust bearing or spacer,
The base-side end surface of the idle gear is adjacent to the one surface of the base-side thrust bearing or spacer, which is in contact with the base-side thrust bearing,
An idle gear support structure characterized in that a clearance in a thrust direction of the idle gear is defined by one surface of the protruding side thrust bearing or thrust plate and one surface of the base side thrust bearing or spacer. The idle gear support structure according to claim 1, wherein the idle gear is a helical gear. 3. The idle gear support structure according to claim 1, wherein the spacer is integrally formed with a gear case that covers the idle gear. The distance between the protruding side end surface and the base side end surface of the idle gear is set to be less than the distance between the protruding side shaft end surface and the base side shaft end surface of the shaft. Item 4. The idle gear support structure according to any one of Items 1 to 3.

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