JP3662624B2 - Gear specification setting method of differential limiting device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a gear specification setting method for a differential limiting device used in a vehicle or the like.
[0002]
[Prior art]
Japanese Unexamined Patent Publication No. 63-76938 discloses a differential limiting device as shown in FIG. The differential limiting device 101 is driven by the engine via the drive gear 103 and the ring gear 105 to rotate. Left and right helical side gears 109 and 111 are disposed opposite to each other in the axial center of the differential case 107, and two pairs of pinion gear housing holes 113 and 115 are provided on the outer periphery of the side gears 109 and 111 in parallel with the rotation shaft. It has been. Helical pinion gears 117 and 119 are housed and supported in these housing holes 113 and 115 so as to be slidable and rotatable. The axially outer portions of the pinion gears 117 and 119 mesh with the left and right side gears 109 and 111, respectively. The parts mesh with each other. Thereby, the left and right side gears 109 and 111 are connected to each other. A spacer 121 is disposed between the side gears 109 and 111. An arcuate recess is formed on the outer periphery of the spacer 121 so as to face the storage holes 113 and 115.
[0003]
Thus, when a difference in driving resistance occurs between the left and right side gears 109 and 111, the driving force is differentially distributed between the side gears 109 and 111 by the rotation of the pinion gears 117 and 119. At this time, the pinion gears 117 and 119 are pressed against the cylindrical wall surfaces of the housing holes 113 and 115 and the arcuate recesses of the spacer 121 by the meshing reaction force with the mating counterpart gear, and a frictional resistance is generated. At the same time, frictional resistance is generated between the end surfaces of the gears 109, 111, 117 and 119 and the differential case 107 and the spacer 121 due to the meshing thrust force of the helical gear. The differential limiting force is obtained by these frictional resistances.
[0004]
[Problems to be solved by the invention]
However, the differential limiting device 101 uses a helical gear of standard gear specifications, and slides between the pinion gears 117 and 119 having the tooth tip arc tooth thickness and the housing holes 113 and 115 of the differential case 107. Since the movement limiting force is obtained, there is a problem that the surface pressure of the pinion gears 117 and 119 serving as the sliding portions is not sufficiently ensured and the surface pressure of these portions is high and seizure occurs. Further, if the storage hole diameter of the differential case 107 is increased to reduce the surface pressure and the number of teeth of the pinion gears 117 and 119 is increased, the apparatus itself becomes larger.
[0005]
The present invention has been made paying attention to such a problem, and prevents the seizure of the pinion gear tooth tip and provides the gear specifications of the differential limiting device capable of obtaining a differential limiting force by a stable frictional resistance. The purpose is to provide a setting method .
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 is a case that is rotated by a driving force of an engine, a pair of helical side gears that are rotatably supported in the case, and a helical pinion gear that meshes with one side gear. A helical pinion gear that meshes with the other side gear and meshes with the pinion gear, and a gear specification of the helical pinion gear of the differential limiting device that is formed in a case and accommodates the helical pinion gear that is slidably rotatable. In the setting method, at least one of the pinion gears has a value (l · tan β + w) × z represented by a tooth width l, a torsion angle β, a circumferential width w of the tooth tip, and the number of teeth z. It is characterized in that the gear specifications are set in a range exceeding twice the tip circumference .
[0007]
The invention according to claim 2 is the gear specification setting method of the differential limiting device according to claim 1, wherein the gear specification includes a tooth width, a torsion angle, and a circumferential width of a tooth tip. The number of teeth and the tip diameter.
[0008]
[Action]
According to the first aspect of the present invention, the driving force of the engine is distributed from each pinion gear to each output shaft side via each side gear. When the vehicle travels straight, the side gears and the pinion gears rotate integrally with the case without relative rotation, and no differential limiting action occurs.
[0009]
When a difference in driving resistance occurs between the output shafts when the vehicle is turning or traveling on a rough road, the driving force of the engine is differentially distributed to each side by the rotation of each pinion gear. At this time, the tooth tip of each pinion gear is pressed against the wall surface of the storage hole by the meshing reaction force with the side gear and the mutual meshing reaction force, and frictional resistance is generated. Further, frictional resistance is generated between the end face of each pinion gear and the case, between the side gear and the case, and between both side gears by the meshing thrust force of the helical gear. These frictional resistances provide a torque sensitive differential limiting action.
[0010]
At this time, the pinion gear that is pressed against the wall surface of the storage hole and slides is set in a range in which the specifications satisfy (l · tan β + w) × z> 2 × (tooth tip circumference). The surface pressure is reduced to prevent the pinion gear from being seized, and the fall in the accommodation hole due to the meshing reaction force is suppressed. As a result, a stable frictional resistance is generated and the differential limiting characteristic is stabilized. This improves the durability of the differential limiting device.
[0011]
According to the second aspect of the present invention, the tooth width of the pinion gear, the torsion angle, the circumferential width of the tooth tip, the number of teeth, and the tooth tip diameter are (l · tan β + w) × z> 2 × (tooth Since it is set in a range that satisfies the (peripheral length), an action equivalent to the action according to the first aspect of the invention can be obtained.
[0012]
【Example】
An embodiment of the present invention will be described with reference to FIGS.
[0013]
FIG. 1 is an overall cross-sectional view of a differential limiting device of this embodiment used in a vehicle. FIG. 2 is an explanatory diagram relating to the specifications of the pinion gear. FIG. 3 is an explanatory diagram of the differential limiting characteristic.
[0014]
The differential case (case) 3 is configured by fixing a case body 5 and a cover 7 with bolts 9. The entire differential limiting device 1 is arranged inside a differential carrier (not shown), and the left and right boss portions 11 and 13 of the differential case 3 are supported by the differential carrier via bearings. The differential carrier is provided with an oil reservoir, and the differential limiting device 1 has its lower part immersed in the oil reservoir in a stationary state, and repels oil from the oil reservoir when rotated.
[0015]
In the differential case 3, left and right side gears 15 and 17 each formed of a helical gear are arranged. The hollow boss portions 19 and 21 of the side gears 15 and 17 are rotatably supported by the support portions 23 and 25 of the differential case 3. Thrust blocks 31 are arranged in the large-diameter holes 27 and 29 formed inside the bosses 19 and 21 so as to straddle the inner periphery thereof, and the free ends of the side gears 15 and 17 are supported and centered. ing.
[0016]
The left and right wheel side output shafts (not shown) pass through the boss portions 11 and 13 of the differential case 3 and are splined to the boss portions 19 and 21 of the side gears 15 and 17. A thrust washer 33 is disposed between the side gears 15 and 17 and the differential case 3, and a thrust washer 35 is disposed between the side gears 15 and 17 (outside of the thrust block 33).
[0017]
The differential case 3 is provided with openings 55, 57, 59, and spiral oil grooves 61, 61 are formed on the inner periphery of the boss portions 11, 13. When the differential limiting device 1 rotates, the oil repelled from the oil reservoir, and when stationary, the oil in the oil reservoir flows into the differential case 3 through the openings 55, 57, 59 and the oil grooves 61, 61. Are supplied to the receiving holes 37 and 39 and the meshing portions of the gears to lubricate them.
[0018]
A plurality of long and short storage holes 37 and 39 are formed in the differential case 3 in the circumferential direction. The first and second gear portions 45, 51, 47, and 53 of the long and short pinion gears 41 and 43 each formed of a helical gear are accommodated in the storage holes 37 and 39 so as to be slidable and rotatable over the entire axial length. Has been.
[0019]
The long pinion gear 41 includes first and second gear portions 45 and 47 and a small-diameter shaft portion 49 that connects them, and the first gear portion 45 meshes with the right side gear 17. The short pinion gear 43 includes first and second gear portions 51 and 53 that do not have a shaft portion therebetween. The first gear portion 51 meshes with the left side gear 15 and the second gear portion 53 is a pinion gear. 41 is engaged with the second gear portion 47 of the motor 41.
[0020]
The gear specifications of the gear portions 45, 47, 51, and 53 of the pinion gears 41 and 43, that is, the torsion angle β of the gear, the tooth width l, the tooth tip width w, the number of teeth z, and the tooth tip diameter d are as follows. It is set to a combination that satisfies the following conditions. In addition, the set tooth width l of each pinion gear 41 and 43 is in contact with each other so as to be slid and rotated in the full-length direction of each storage hole 37 and 39.
[0021]
The setting conditions will be described with reference to FIG. 2A is a front view of the first and second gear portions 45 and 47 of the pinion gear 41, FIG. 2B is a side view thereof, and FIG. 2C is a development view of FIG. 2B. . Here, description will be made assuming that the tooth tips of the gear portions 45 and 47 and the wall surface of the storage hole 37 are in contact with each other. In addition, although it demonstrates using the figure of the 1st and 2nd gear parts 45 and 47 of the pinion gear 41 here, the gear specifications of the 1st and 2nd gear parts 51 and 53 of the pinion gear 43 are the same as FIG. The rest is the same except for the twist direction.
[0022]
The contact length of all teeth obtained by multiplying the contact length B in the circumferential direction between the tooth tip surface of one tooth of the gear portions 45 and 47 shown in FIG. The ratio between the height (B × z) and the tooth tip circumference A of the gear portions 45 and 47 is defined as a contact ratio η, and the condition is that η ≧ 2 is satisfied. This relationship is expressed as in equation (1). This condition is preferably η ≧ 2.5.
[0023]
(B × z) / A ≧ 2 (1)
Here, B: contact length in the circumferential direction of one tooth (= t + w = 1 / tan β + w)
z: number of teeth A: tooth circumference (= πd)
t: l · tan β (see FIG. 2 (c))
w: circumferential width of tooth tip l: tooth width β: twist angle d: tooth tip diameter η: contact rate These A and B are substituted into equation (1) to obtain equation (2).
[0024]
[Expression 1]
{(L · tan β + w) × z} / πd ≧ 2 (2)
The combination of the tooth width l, the torsion angle β, the tooth tip circumferential width w, the number of teeth z, and the tooth tip diameter d is set so as to satisfy the equation (2).
[0025]
Thereby, the tooth width l and the tooth tip width w of the gear portions 45 and 47 are sufficiently secured, and the collapse is suppressed.
[0026]
Next, the operation of the differential limiting device 1 will be described.
[0027]
The driving force of the engine that rotates the differential case 3 is distributed from the pinion gears 41 and 43 to the left and right output shafts via the side gears 15 and 17. When the vehicle is traveling straight, the side gears 15 and 17 and the pinion gears 41 and 43 rotate integrally with the differential case 3 without relative rotation, and depend on the torsion angle between the gears 15, 17, 41, and 43 according to the input torque. As a result of the frictional resistance obtained by the meshing thrust force or the meshing reaction force as in turning described later, the differential limiting force is appropriately obtained.
[0028]
When a driving resistance difference occurs between the output shafts when the vehicle is turning or traveling on a rough road, the driving force of the engine is differentially distributed to the left and right sides by the rotation of the pinion gears 41 and 43. At this time, the tooth tips of the pinion gears 41 and 43 are pressed against the wall surfaces of the storage holes 37 and 39 by the meshing reaction force with the side gears 17 and 15 and the mutual meshing reaction force, thereby generating frictional resistance. Further, frictional resistance is generated between the end surfaces of the pinion gears 41 and 43 and the differential case 3 by the meshing thrust force of the helical gear, and between the side gears 15 and 17 and the differential case 3 via the thrust washer 33, and the thrust washer. Friction resistance is generated between the side gears 15 and 17 via 35. These frictional resistances provide a torque-sensitive differential limiting action.
[0029]
At this time, the pinion gears 41 and 43 that slide while being pressed against the wall surfaces of the storage holes 37 and 39 are formed with gear specifications that satisfy the contact ratio η ≧ 2, so that the tooth tip pressure is reduced. Seizure of the lever is prevented, and the fall in the storage holes 37 and 39 due to the meshing reaction force is suppressed.
[0030]
If the gear specifications of the pinion gears 41 and 43 are set so that the contact ratio η is less than 2, the frictional resistance becomes unstable, so that, for example, as shown in FIG. In this case, a fluctuation range is generated from the straight line. FIG. 3 shows the measurement results when the contact ratio η = 1.057, and the portions C and D (shaded portions) in the figure indicate the fluctuation range of the output shaft torque. As the contact rate η becomes as small as η = 0.523, for example, the fluctuation range increases.
[0031]
Thus, according to the present embodiment, seizure between the pinion gears 41 and 43 and the housing holes 37 and 39 at the time of differential limitation is prevented, and the differential limiting characteristic is stabilized by a stable frictional resistance. 1 durability is improved.
[0032]
【The invention's effect】
As apparent from the above description, according to the invention described in claim 1, the specifications of the pinion gear are set in a range satisfying (l · tan β + w) × z> 2 × (tooth tip circumference). Therefore, seizure of the pinion gear is prevented by reducing the tooth surface pressure, and tilting in the accommodation hole due to the meshing reaction force is suppressed. Thereby, the differential limiting characteristic is stabilized by the stable frictional resistance, and the durability of the differential limiting device is improved.
[0033]
According to the second aspect of the present invention, the tooth width of the pinion gear, the torsion angle, the circumferential width of the tooth tip, the number of teeth, and the tooth tip diameter are (l · tan β + w) × z> 2 × (tooth Since it is set in a range that satisfies (peripheral length), an effect equivalent to the effect of the invention of claim 1 can be obtained.
[Brief description of the drawings]
FIG. 1 is an overall cross-sectional view of an embodiment.
FIG. 2 is an explanatory diagram relating to specifications of a pinion gear according to one embodiment.
FIG. 3 is an explanatory diagram of a differential limiting characteristic of an embodiment.
FIG. 4 is an overall sectional view of a conventional example.
[Explanation of symbols]
3 Differential case
15, 17 Side gear (helical side gear)
37, 39 Storage holes 41, 43 Pinion gear (helical pinion gear)
45, 51 First gear portion 47, 53 Second gear portion A Pinion gear tooth tip circumference B Pinion gear circumferential contact length β Torsion angle l Tooth width w Tooth tip circumferential width z Number of teeth d Tooth tip diameter η Contact rate

Claims (2)

A case rotating by the driving force of the engine, a pair of helical side gears rotatably supported in the case, a helical pinion gear meshing with one side gear, a helical pinion gear meshing with the other side gear and meshing with the pinion gear, and case A setting method for setting gear specifications of the helical pinion gear of a differential limiting device comprising a storage hole that is formed to be slidably rotatable to store the helical pinion gear,
In at least one of the pinion gears, a value (l · tan β + w) × z represented by a tooth width l, a torsion angle β, a circumferential width w of the tooth tip, and the number of teeth z is twice the tooth tip circumferential length of the gear. A gear specification setting method for a differential limiting device, wherein the gear specification is set in a range exceeding . A gear specification setting method for a differential limiting device according to claim 1 ,
A gear specification setting method for a differential limiting device , wherein the gear specifications are a tooth width, a twist angle, a circumferential width of a tooth tip, the number of teeth, and a tooth tip diameter .

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