JP4388688B2 - Gear device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear device, and more particularly to a gear device in which power transmission between a driving gear and a driven gear supported by different members is performed via an intermediate gear.
[0002]
[Prior art]
In general, an idler is provided in a path for transmitting the rotational force of the crankshaft of the engine to, for example, a balance shaft or an oil pump in order to properly set the distance between the shafts and the rotation direction.
[0003]
On the other hand, in the case where the gear trains that mesh with each other are arranged across a plurality of members, it is difficult to ensure the desired inter-axis distance accuracy, and in some cases, the meshing gap may be excessive. Such an improper meshing gap leads to an increase in backlash and increases noise.
[0004]
A technique for reducing noise by providing scissors gears in each of the meshing portion of the driving gear and the intermediate gear and the meshing portion of the intermediate gear and the driven gear (see Japanese Utility Model Publication No. 4-13468) is known. According to this, the number of parts and the number of manufacturing steps tend to increase.
[0005]
[Problems to be solved by the invention]
The present invention has been devised to solve such problems of the prior art, and its main purpose is to be supported by different members, so it is difficult to increase the meshing accuracy between the gears. Even in such a case, an object of the present invention is to provide an improved gear device that can suppress the generation of noise while minimizing the increase in the number of parts and the number of manufacturing steps.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the invention of claim 1 of the present application includes a drive gear (3) provided on a crankshaft (2) rotatably supported by a cylinder block (23), and an oil pump housing (5). ) Supported by a driven gear (4) and an intermediate gear (1) for transmitting power from the drive gear to the driven gear, the intermediate gears being coupled to each other so as to be capable of relative angular displacement. The scissors gear is composed of a main gear (21) and a sub gear (22) , the main gear is located outside the sub gear in the crank axis direction, the drive gear meshes with both the main gear and the sub gear, The driven gear meshes only with the main gear, and the driving gear, the driven gear, and the intermediate gear are arranged in a line on the same plane that is perpendicular to the axis of the crankshaft, with their axially outer end faces aligned. was assumed that
[0007]
In this way, it is sufficient to use a scissors gear for one of the two gears supported between the different members for which it is difficult to obtain the required inter-axis distance accuracy, thereby minimizing the increase in the number of parts and the number of manufacturing steps. The backlash between the gears can be reduced while keeping the gears at a minimum. In particular, if the intermediate gear and the driven gear are supported by the same member, the gears supported by the common member can obtain the required inter-axis distance accuracy with machining accuracy. This is advantageous when the driven gear and the intermediate gear are sub-assembled.
[0008]
According to a second aspect of the present invention, in addition to the above configuration, the oil pump housing includes a support portion (31) for supporting the intermediate gear, and a support portion (34) for the oil pump housing to support the driven gear. A rib (33) for connecting the two is formed integrally with the oil pump housing .
[0009]
Furthermore, in the invention of claim 3, the oil pump housing is fastened to another member with bolts inserted through a plurality of boss portions (32), and the oil pump housing supports the intermediate gear and the plurality of oil pump housings. The rib (33) which connects the boss | hub part is integrally formed . As a result, the support rigidity of the intermediate gear is further increased and the rotation of the intermediate gear is stabilized, so that the meshing noise between the intermediate gear and the driven gear is further reduced.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0011]
1 and 2 show a mounting portion of an idler gear as an intermediate gear to which the present invention is applied. The idler gear 1 is located at an intermediate position in a path for transmitting the rotational force of a crank gear 3 (drive gear) provided on the crankshaft 2 to a pump gear 4 (driven gear) provided on a lubricating oil pump (not shown). It is provided with a spur gear having the same number of teeth as that of the crank gear 3 and is engaged with both the crank gear 3 and the pump gear 4 while being attached to an oil pump housing 5 disposed in the oil pan. Yes.
[0012]
The crank gear 3, the idler gear 1 and the pump gear 4 are arranged in a line on one plane orthogonal to the axis of the crankshaft 2 with the axial outer end faces aligned, thereby reducing the dimension in the crankshaft direction. It has been.
[0013]
A fixed shaft receiving hole 6 is formed in the front end wall in the crankshaft direction of the oil pump housing 5. The base end portion of the fixed shaft 7 is tightly fitted into the fixed shaft receiving hole 6 by, for example, press fitting. The idler gear 1 formed by press-fitting and fixing a metal bearing 8 to the shaft insertion hole is pivotally attached to the fixed shaft 7.
[0014]
At the shaft end of the fixed shaft 7, a retaining flange 9 is formed. The idler gear 1 is sandwiched between the retaining flange 9 and the oil pump housing 5, and a fixing bolt is attached to the oil pump housing 5. The fixed shaft 7 in a state where the idler gear 1 is pivotally supported is fixed to the oil pump housing 5 by screwing 10.
[0015]
A recess 11 is formed in the bottom surface of the fixed shaft receiving hole 6 by a casting process. One of the recesses 11 is concentric with the center of the female screw hole 12 screwed with the fixing bolt 10 and is connected to a gap between the bolt insertion hole 13 of the fixing shaft 7 and the fixing bolt 10. The other of the recesses 11 bites into the inner peripheral surface of the fixed shaft receiving hole 6, and this biting continues to the axial groove 14 reaching the opening surface of the fixed shaft receiving hole 6.
[0016]
Connected to the axial groove 14 is a lubricating oil discharge passage 15 connected to a discharge port of an oil pump (not shown). The discharge passage 15 is drilled in an oblique direction from the opening of the fixed shaft receiving hole 6. The discharge passage 15 is formed so as to directly communicate with the discharge port of the oil pump, so that the oil passage configuration is simplified and the passage length is shortened.
[0017]
A radial through hole 16 is formed in a portion of the fixed shaft 7 that is located at the intermediate portion in the axial direction of the metal bearing 8. The radial through hole 16 communicates with a gap between the bolt insertion hole 13 of the fixed shaft 7 and the fixed bolt 10.
[0018]
The lubricating oil supplied from the discharge passage 15 flows into the axial groove 14, and part of the lubricating oil flows to the sliding contact surface between the axial end surface of the idler gear 1 and the oil pump housing 5 through the axial groove 14, and the rest It flows into the recess 11. Then, it flows out from the recess 11 to the sliding contact surface between the fixed shaft 7 and the metal bearing 8 through the gap between the bolt insertion hole 13 of the fixed shaft 7 and the fixed bolt 10 and the radial through hole 16. Further, the oil flows from the radial groove 17 formed on the contact surface of the fixed shaft 7 with the retaining flange 9 along the front surface of the idler gear 1 into the oil pan.
[0019]
In this way, the lubricating oil for the working surfaces of the thrust and radial loads in the idler gear 1 is sufficiently supplied.
[0020]
The idler gear 1 is supported by the oil pump housing 5, and the crank gear 3 is supported by the cylinder block 23. As described above, when the two gears are supported by different members, it is difficult to set the inter-axis distance accuracy to a predetermined accuracy. In particular, if the distance between the axes of the two gears becomes excessive, the meshing gap between the two gears becomes large, which can cause an increase in noise.
[0021]
In view of this point, in the present invention, the idler gear 1 is constituted by a scissors gear composed of a main gear 21 and a sub gear 22 that are coupled to each other so as to be capable of relative angular displacement. This scissor gear is constructed by connecting main and sub gears 21 and 22 via spring means that exerts a resilient force in the circumferential direction for shifting the phase angle from each other. Since there is no change, the detailed explanation is omitted.
[0022]
Here, a case is assumed in which the distance between the shafts of the idler gear 1 and the crank gear 3 becomes excessive due to manufacturing errors and assembly errors between the oil pump housing 5 and the cylinder block 23. In this case, the main and sub gears 21 and 22 connected via the spring means that exerts the elastic force in the circumferential direction are shifted in the circumferential direction in accordance with the increase of the meshing gap, and the tooth thickness is increased. Has the same effect as. Therefore, even if the distance between the axes is excessive, the backlash does not increase and the generation of noise is suppressed. Lubricating oil is supplied to the sliding contact surfaces of the main and sub gears 21 and 22 from an oil hole 30 provided in the shaft support portion of the idler gear 1 so as to be continuous with the radial through hole 16 of the fixed shaft 7.
[0023]
On the other hand, the idler gear 1 and the pump gear 4 are assembled to an oil pump housing 5 which is a common member. In the case of two shafts supported by a common member in this way, the required inter-axis distance accuracy can be obtained with machining accuracy, and this side is meshed with ordinary gears. According to this, since the thickness of the pump gear 4 can be made smaller than the thickness of the idler gear 1, it can contribute to compactness.
[0024]
By the way, between the support portion 31 of the idler gear 1 and the support portion 34 of the pump gear 4 with respect to the oil pump housing 5, and the support portions 31 and 34 of both gears and the oil pump housing 5 are fixed to an oil pump body (not shown). A plurality of screw bosses 32 for screwing the bolts to be connected are connected by ribs 33, respectively. As a result, the rigidity of the support portions 31 and 34 of both gears is increased and the rotation of both gears 1 and 4 is stabilized, so that it is possible to further reduce the meshing noise of the gears.
[0025]
【The invention's effect】
As described above in detail, according to the configuration of claim 1 of the present invention, the scissors gear may be used only for one of the two gears supported between the different members for which it is difficult to obtain a highly accurate inter-axis distance. Therefore, a great effect can be achieved in reducing the backlash between the gears and suppressing the noise without causing a significant increase in the number of parts and the number of manufacturing steps. Also, since the required distance accuracy between the shafts supported by the common member can be obtained with machining accuracy, this side can be meshed with normal gears, and the idler gear consisting of scissors gear can be driven by the driven machine. If it is assembled to a certain oil pump housing, it is possible to install an oil pump sub-assembled by pre-installing idler gears outside the main line, so that it can be assembled to the engine on the main line. This is effective in attempting to shorten the line length.
[0026]
If the configuration of claim 2 or claim 3 is added to the above configuration, the support rigidity of the idler gear and the pump gear is increased and the rotation thereof is further stabilized, so that the meshing noise of these gears can be further reduced. It is effective.
[Brief description of the drawings]
FIG. 1 is a front view of an essential part of an engine provided with an idler gear to which the present invention is applied. FIG. 2 is a cross-sectional view taken along a plane passing through the center of each axis.
DESCRIPTION OF SYMBOLS 1 Idler gear 3 Crank gear 4 Pump gear 5 Oil pump housing 21 Main gear 22 Sub gear 23 Cylinder block 31 Idler gear support part 32 Screw boss 33 Rib 34 Pump gear support part

Claims (3)

A gear device having a drive gear provided on a crankshaft rotatably supported by a cylinder block, a driven gear supported by an oil pump housing, and an intermediate gear for transmitting power from the drive gear to the driven gear. And
The intermediate gear is composed of a scissors gear composed of a main gear and a sub gear that are coupled to each other so as to be capable of relative angular displacement, the main gear is located on the outer side in the crank axis direction than the sub gear, and the The drive gear meshes, the driven gear meshes only with the main gear,
The gear device, wherein the drive gear, the driven gear, and the intermediate gear are arranged in a line on the same plane orthogonal to the axis of the crankshaft, with the axially outer end surfaces thereof aligned. Wherein the ribs the oil pump housing and the support portion where the oil pump housing to support the intermediate gear is linked between the support portion for supporting the driven gear is integrally formed with the oil pump housing The gear device according to claim 1. The oil pump housing is fastened to another member with bolts inserted through a plurality of boss portions, and a rib for connecting the support portion supporting the intermediate gear and the plurality of boss portions is integrally formed by the oil pump housing. gear device according to claim 1 or 2, characterized in that it is.

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