JP2008095724A - Contrate gear and differential device using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contrate gear and a differential device using this, which prevents an edge-like portion from forming, and improves the durability in the contrate gear. <P>SOLUTION: In the differential device using contrate gears 1, 3 for a pair of output-side side gears 1, 3, a tooth height H from the rotation center of the contrate gears 1, 3 radially outward is continuously made low, so that an increasing portion 105 having a rotational width W is provided in an addendum flank top surface 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a face gear and a differential device using the same.

  Patent Document 1 discloses a surface gear transmission.

  The face gear does not need to accurately position the pinion gear, which is the counterpart gear, in the axial direction. In addition, for example, compared to a device using a bevel gear (bevel gear), the device is arranged in the axial direction. There are advantages such as compactness.

  In the case of the face gear, friction due to the rotational speed difference occurs between the pinion gear and the pinion gear except for the part that rotates at the same speed, and it is necessary to change the pressure angle α of each tooth over the tooth width direction to reduce this. The above document describes an example in which the pressure angle α is minimized (α = 0 °) at the radially innermost portion of the face gear and maximized (α = 40 °) at the radially outermost portion. Yes.

  However, when the pressure angle α is changed in the tooth width direction in this way, the tooth height of the face gear needs to be matched with the minimum tooth height in the radially innermost part or the radially outermost part, and the tooth height is changed to the tooth width. When it is formed constant in the direction, the tooth height of the face gear is lowered, the effective portion of each tooth is reduced, and the power that can be transmitted (power transmission capacity) is reduced.

The above document proposes to increase the power transmission capacity by increasing the tooth height from the radially outermost part to the radial intermediate part without making the tooth height constant in the tooth width direction.
JP 62-151649 A

  However, when the pressure angle α is increased, the rotational width of the tip (end of the tooth) of each tooth becomes narrower and becomes an edge, and stress is concentrated on the edge of the tooth when forming the face gear. The durability is lowered, and when the face gear is cured and heat-treated, the edge-shaped portion may be cracked.

  Accordingly, an object of the present invention is to provide a face gear that can prevent the formation of an edge-shaped portion of the face gear and improve the durability of the face gear, and a differential device using the face gear.

  The face gear according to claim 1 is characterized in that an increasing portion in the rotational direction width is provided on the top surface of the tooth end by continuously decreasing the tooth height from the center of rotation outward in the radial direction.

  According to a second aspect of the present invention, in the face gear according to the first aspect, the increasing portion has a portion having a constant width in the rotation direction from the rotation center to the outside in the radial direction.

  A third aspect of the present invention is the face gear according to the first or second aspect, wherein the increased portion is a curved surface.

  According to a fourth aspect of the present invention, in the face gear according to the first aspect, the increasing portion is formed to extend radially outward from a pitch line of the face gear.

  The differential device according to claim 5 includes a differential case that rotates by receiving a driving force of a prime mover, a pinion gear that revolves together with the differential case, and a pair of output side gears that mesh with the pinion gear and transmit the driving force to a wheel side. And the pair of output side gears is the face gear according to any one of claims 1 to 4.

  In the face gear according to the first aspect, the tooth height is continuously lowered from the center of rotation to the outer side in the radial direction, thereby forming an increasing portion of the width in the rotational direction on the apical surface.

  If the tooth height of the face gear is lowered from the center of rotation toward the outside in the radial direction, the thick part of the tooth becomes the top land, and an increased part of the width in the direction of rotation can be formed, and the end of the tooth has an edge shape It is possible to prevent the portion from being formed.

  Therefore, when the face gear is formed, stress concentration on the edge-shaped portion can be prevented, and the durability of the face gear can be improved. Further, since the edge-shaped portion is not formed, no cracking occurs during the curing heat treatment.

  In the face gear according to the second aspect, since the increased portion has a portion with a constant width in the rotation direction from the rotation center to the outside in the radial direction, the width in the rotation direction of the top land is not narrowed, and an edge shape is formed at the end of the tooth. It is possible to prevent the portion from being formed.

  In the face gear according to the third aspect, since the increased portion is formed of a curved surface, local strong tooth contact with the counterpart gear is prevented, and abnormal noise, vibration and abnormal wear are prevented. In the face gear according to the fourth aspect, since the increased portion is formed to extend radially outward from the pitch line of the face gear, the range in which the tooth height is lowered is narrow, and the meshing efficiency can be kept high.

  The differential device according to claim 5 can obtain a necessary power transmission capacity for the above-described reason, and can be configured at a low cost by using a low-cost face gear as a side gear as described above. Abnormal noise, vibration and abnormal wear in the gear are prevented, and durability is improved.

<One Example>
1 and 2, side gears 1 and 3 (face gear) and a differential device 5 (one embodiment of the present invention) using them will be described. In the following description, the left and right directions are the four-wheel drive vehicle in which the differential device 1 is used and the left and right directions in FIG.

[Features of side gears 1 and 3 and differential device 5]
The side gears 1 and 3 (face gears) have a tooth width W (rotational direction width) on the top land 7 (end tooth top surface) by continuously lowering the tooth height H from the rotation center to the outside in the radial direction. An increase unit 105 is provided.

  The differential device 5 includes a differential case 9 that rotates in response to a driving force of an engine (prime mover), a pinion gear 11 that revolves together with the differential case 9, and a pair of output sides that mesh with the pinion gear 11 and transmit the driving force to the wheels. Side gears 1 and 3 are provided.

[Configuration of Differential Device 5]
The differential device 5 is accommodated in a differential carrier provided with an oil sump, and includes the side gears 1 and 3, the differential case 9, the pinion gear 11, the pinion shaft 13, and the like.

  The differential case 9 is formed by fixing the cover 15 and the casing body 17 with bolts 19. Each boss portion 21, 23 is supported by a differential carrier by a bearing, and input from a ring gear bolted to each flange portion 25, 27. It is driven to rotate by the driving force of the engine.

  In the side gears 1 and 3, the boss portions 29 and 31 are supported by the support portions 33 and 35 of the cover 15 and the casing body 17, and are connected to the wheel side via drive shafts connected to the spline portions 37 and 39. A washer 40 that receives the meshing reaction force of the side gears 1 and 3 is disposed between the side gears 1 and 3 and the cover 15 and the casing body 17. A radial oil groove 42 is formed in the washer 40 so as to extend radially outward from the rotational axis side. The pinion gear 11 is a spur gear and is supported by the pinion shaft 13 to mesh with the side gears 1 and 3. The casing body 17 is formed with a spherical portion 41 that receives the centrifugal force of each pinion gear 11, and the pinion shaft 13 is assembled through the through-hole 43 of the casing body 17 and is prevented from being detached by a pin 45.

  Further, the casing body 17 includes radial oil grooves 47 and 49 that extend from the rotational axis side of the pinion gear 11 to the radially outer side (in FIG. 1, the rotational axis direction of the differential case 9). 47 and 49 are provided with oil reservoirs 51 and 53 facing the meshing portions of the side gears 1 and 3 and the pinion gear 11, and the cover 15 and the casing body 17 are provided in the radial direction communicating with the respective oil reservoirs 51 and 53. Oil grooves 55 and 57 are provided, and the oil grooves 55 and 57 open to the inner periphery of the boss portions 21 and 23. Each boss portion 21, 23 is provided with spiral oil grooves 59, 61 on the inner periphery, and oil passages 63, 65 communicating the oil grooves 59, 61 with the outside, and the pinion shaft 13 and each An oil groove 67 is provided between the pinion gear 11 and the pinion gear 11.

  The oil of the differential carrier is sucked into the inside by the pumping action of the spiral oil grooves 59, 61 accompanying the rotation of the differential case 9, and the pressure causes the drive shaft and the inner periphery of the boss portions 21, 23 and the spline portions 37, 39, and after receiving the centrifugal force and lubricating them through the meshing portion of the side gears 1 and 3 and the pinion gear 11 and the oil groove 67 between the pinion shaft 13 and the pinion gear 11, the gear 1 , 3 and the gear 11 are subjected to pressure, and the washers 40, 40 are lubricated through the oil grooves 47, 49, the oil reservoirs 51, 53, and the oil grooves 55, 57 of the spherical surface portion 41. Return to the inner circumference of the bosses 21 and 23 and repeat such circulation to lubricate and cool each lubricated part, especially the side gears 1 and 3 and the pinion Sufficiently lubricate the meshing portions of the A 11.

  As shown in FIG. 2, the driving force of the engine that rotates the differential case 9 is transmitted from the pinion shaft 13 and the pinion gear 11 to the left and right wheels via the side gears 1 and 3 and the drive shaft. This transmission is performed by the pinion gear 11 and the side gears 1 and 3 meshing on the meshing line (pitch line) 103. The top lands 7 of the side gears 1 and 3 have a constant tooth width H with a constant tooth width W and hung outward in the radial direction. Note that the tooth width W does not necessarily have to be a constant tooth width W as in the embodiment, and the tooth width is continuously or stepwise narrowed by decreasing the tooth height toward the radially outer side as the predetermined width W1 on the pitch line side. The widths W2 and W3 may be set. In this case, the relationship between the predetermined widths of W1, W2 and W3 becomes W1> W2> W3 as it goes to the outer diameter side. Also in this case, the effects of the present application can be shared.

  As shown in FIG. 3, the side gears 1 and 3 have a top land portion 101 on the rotation center side that is a tooth height H that is the tooth height of the reference tooth shape calculated by the tooth shape, and is hung outward in the radial direction starting from the meshing line 103. Thus, the tooth height H is continuously lowered, and the increasing portion 105 is provided. The increased portion 105 has a constant tooth width W extending radially outward from the center of rotation. Further, in the side gears 1 and 3 shown in FIG. 3B, the inclined surface of the increasing portion 105 is formed linearly, and in the side gears 1 and 3 shown in FIG. 3C, the inclined surface of the increasing portion 105 is formed. It is curved. In FIG. 3, a broken line 107 indicates the shape of a conventional face gear in which the tooth height H is not lowered. The side gears 1 and 3 have the power transmission capacity necessary for transmitting the driving force of the engine as described above while preventing the formation of the edge-shaped portion by providing the increased portion 105 of the tooth width W in this way. It has gained.

  The side gears 1 and 3 set the starting point for lowering the tooth height H as necessary at the radially innermost portion 109 of the top land 7 and hang on the radially outer side over the entire top land 7. May be lowered. Further, the tooth width W which is the width of the top land 7 takes into account the relationship with the hardened layer depth of the hardening heat treatment, for example, and in the case of forging, the plastic fluidity of the work material and the die life of the forging die are reduced. Although it will be considered, it is desirable to set in the range of 0 <W <1 × m (m: module).

[Effects of side gears 1 and 3 and differential device 5]
The side gears 1 and 3 have the following effects.

  Since the tooth height H is continuously lowered and the increased portion 105 is provided on the top land 7 by being hung on the radially outer side where the tooth width W becomes narrower, an edge-like portion is prevented from being formed at the end of the tooth. Stress concentration due to the edge portion is prevented, and the durability of the face gear is improved. In addition, when using a forging die as a means of forming the tooth mold, the forging die has a bottom shape that does not have an edge shape, so that the life of the forging die is increased and the edge of the face gear at the top of the tooth end is increased. Since no portion is formed, the side gears 1 and 3 are not cracked during the heat treatment of the face gear, the yield is greatly improved, and the manufacturing cost is reduced accordingly.

  Further, by configuring the increasing portion 105 with a curved surface, strong tooth contact with the pinion gear 11 is prevented, and abnormal noise, vibration, and abnormal wear are prevented.

  Further, the present invention reduces the tooth height H within a range in which the formation of the edge-shaped portion is prevented, and the effective gears (allowable load) of the side gears 1 and 3 are not impaired and the meshing efficiency with the pinion gear 11 is affected. Not give. Further, the side gears 1 and 3 have the tooth height H lowered from the meshing line 103 in the radial direction, and since the range in which the tooth height H is lowered is narrow, the meshing efficiency is kept high.

  The differential device 5 can obtain a necessary power transmission capacity for the above reasons, and can be configured at a lower cost by using the low-cost side gears 1 and 3. And vibration and abnormal wear are prevented, and durability is improved.

  Further, due to the characteristics of the face gear, it is not necessary to accurately position the pinion gear 11 in the axial direction with respect to the side gears 1, 3, so that the assembly can be facilitated and the cost can be reduced, and the axial direction of the differential device 5 can be reduced. It becomes compact and the in-vehicle performance is improved.

[Other embodiments within the scope of the present invention]
The face gear of the present invention can be widely applied to a power interrupting device using a gear transmission mechanism in addition to a differential device.

It is sectional drawing which shows the side gear (face gear) of one Example, and a differential apparatus using the same. It is a perspective view which shows the side gear of one Example, a pinion gear, and a pinion shaft. (A) It is a front view which shows the top land of the side gear of one Example. (B) It is a side view which shows the top land of the side gear of one Example. (C) It is a side view which shows the top land of the side gear of another Example.

Explanation of symbols

1,3 Side gear (face gear)
5 Differential device 7 Top land (end tooth top surface)
9 Differential case 11 Pinion gear 13 Pinion shaft 105 Increased part H Tooth height W Tooth width (rotation direction width)

Claims (5)

  A face gear characterized in that an increased portion in the rotational direction width is provided on the top surface of the tooth end by continuously decreasing the tooth height from the center of rotation to the outside in the radial direction. The face gear according to claim 1,
The face gear according to claim 1, wherein the increasing portion has a portion having a constant width in the rotation direction from the rotation center to the outside in the radial direction. The face gear according to claim 1 or 2,
A face gear characterized in that the increased portion is curved. The face gear according to claim 1,
The face gear is characterized in that the increasing portion is formed to hang radially outward from a pitch line of the face gear. A differential case that rotates in response to the driving force of the prime mover, a pinion gear that revolves together with the differential case, and a pair of output side gears that mesh with the pinion gear and transmit the driving force to the wheel side;
The differential gear according to any one of claims 1 to 4, wherein the pair of output side gears is the face gear according to any one of claims 1 to 4.

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