Gear Lubricating Oil Quantity Calculation Method

Abstract

To provide a method for calculating a lubricant amount of a gear, which can appropriately calculate a lubricant amount between tooth surfaces to be evaluated in a gear where transition of a meshing point occurs.SOLUTION: A method for calculating a lubricant amount of a gear comprises: setting a lubricant amount calculation area 12 in which a lubricant amount is calculated, along a drive-side tooth surface 8 of a ring gear 2 and in a vicinity area that does not protrude from the drive-side tooth surface 8; setting a contact line C between a tooth 4 of the ring gear 2 and a tooth 5 of a pinion gear 3 passing through a meshing point; and using the specifications of the gear and the specifications of the lubricant, and moving the lubricant oil amount calculation area 12 or the contact line C with the transition of the meshing point, to calculate the lubricant amount in the lubricant amount calculation area 12 with fluid analysis means by an arithmetic processing device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for calculating the lubricating oil amount of gears, and more particularly to a method for calculating the lubricating oil amount existing between the tooth surfaces of a ring gear and a pinion gear.

Background Art

[0002] For example, a bevel gear used in a final reduction gear of a vehicle is composed of a pinion gear (small-diameter gear) and a ring gear (large-diameter gear). When the input and output shafts of both gears are offset, the rotation axes of the two gears are in a twisted position. Such a gear is called a hypoid gear. In addition to the characteristics of excellent sound vibration performance during meshing rotation and a large transmissible torque, the meshing point of the hypoid gear has a characteristic that it transitions in the tooth trace direction (generally, the tooth surface slides). Regarding this characteristic, when focusing on the ring gear, on the tooth surface of the ring gear where the tooth trace bends and extends substantially in the radial direction, among the meshing points with the teeth of the above-mentioned transitioning pinion gear, the meshing portion at the radially inner end is considered to have the greatest stress.

[0003] Therefore, in Patent Document 1 below, chamfers are provided at the portion (corner portion) where the tooth surface of the tooth of the ring gear intersects with the radially inner end face of the tooth, so as to avoid stress concentration at this corner portion. The chamfered portion described in this prior art is provided on both the drive (driving) side tooth surface and the coast (driven) side tooth surface of the tooth of the ring gear, and is configured by a so-called C chamfer that obliquely and planar removes the corner portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in recent years, with the increasing demand for transmitted torque in vehicles, a decrease in transmission efficiency in gears has become a problem. This is presumably because, for example, when the lubrication state between the tooth surfaces of a hypoid gear is the same, as the transmitted torque increases, the lubricating oil thickness between the tooth surfaces decreases, and the friction coefficient between the tooth surfaces increases. That is, as the transmitted torque increases, the lubrication mode between the tooth surfaces changes in the order of hydrodynamic lubrication, mixed lubrication, and boundary lubrication, with the oil film thickness becoming smaller (thinner). In particular, in the region from mixed lubrication to boundary lubrication, there is almost no lubricating oil between the tooth surfaces, so the friction coefficient between the tooth surfaces increases.

[0006] To analyze such a problem, it is considered a good strategy to determine the amount of lubricating oil present between the tooth surfaces of the ring gear and the pinion gear and evaluate that amount of lubricating oil. However, no specific method has been developed to appropriately determine the amount of lubricating oil present between the tooth surfaces of a hypoid gear. Also, even if the amount of lubricating oil present between the tooth surfaces of a hypoid gear can be calculated by an existing computer application software (hereinafter simply referred to as an app), that is, a fluid analysis method by an arithmetic processing unit, in a gear such as a hypoid gear where the meshing point transitions as described above, no part has been found for which the amount of lubricating oil should be calculated and evaluated.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a method for calculating the amount of lubricating oil in a gear that can appropriately calculate the amount of lubricating oil between tooth surfaces to be evaluated in a gear where the meshing point transitions.

Means for Solving the Problems

[0008] A method for calculating the amount of lubricating oil in a gear according to an aspect of the present invention for achieving the above object is in a gear in which the meshing point of the teeth of a ring gear and a pinion gear transitions as they rotate meshingly, a method for calculating the amount of lubricating oil in a gear that calculates the amount of lubricating oil present between the tooth surfaces of the ring gear and the pinion gear in the leading region in the transition direction of the meshing point, A lubricating oil amount calculation region for calculating the lubricating oil amount is set in the vicinity region along and not protruding from the tooth surface of either the ring gear or the pinion gear, and a contact line between the teeth of the ring gear and the teeth of the pinion gear passing through the meshing point is set. Using the specifications of the ring gear and the pinion gear and the specifications of the lubricating oil, and moving the lubricating oil amount calculation region or the contact line as the meshing point transitions, the lubricating oil amount within the lubricating oil amount calculation region is calculated by fluid analysis means of an arithmetic processing unit.

Advantages of the Invention

[0009] As described above, according to the present invention, since the lubricating oil amount between the tooth surfaces in the forward region in the transition direction of the meshing point can be calculated by the fluid analysis means of the arithmetic processing unit, the lubricating oil amount involved in future meshing can be obtained, and therefore the lubricating oil amount between the tooth surfaces of the gear to be evaluated can be appropriately obtained.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the lubricating oil amount calculation method for the gears of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a lubricating oil amount calculation area showing a first embodiment of the lubricating oil amount calculation method for the gears of the present invention, FIGS. 2 and 3 are explanatory diagrams of the setting of the lubricating oil amount calculation area in FIG. 1, and FIG. 8 is an explanatory diagram showing an example of the hypoid gear 1. First, the hypoid gear 1 will be briefly described. The hypoid gear 1 is composed of a combination of a ring gear (large-diameter gear) 2 with the entire gear being ring-shaped and a pinion gear (small-diameter gear) 3 with the entire gear being frustum-shaped. An axial member (not shown) is integrally coupled to the large-diameter side of the frustum of the pinion gear 3. Since the rotation axes of the pinion gear 3 and the ring gear 2 are offset in the vertical direction in the figure, their rotation axes are in a twisted position.

[0012] The teeth 4 and 5 formed on the ring gear 2 and the pinion gear 3 of the hypoid gear 1 are so-called spiral teeth. The teeth 4 of the ring gear 2 extend substantially in the radial direction while the tooth flanks are curved, and the teeth 4 have a radially inner end face 6 and a radially outer end face 7. Among these teeth 4 and 5, the convex tooth surface of the ring gear 2 and the concave tooth surface of the pinion gear 3 constitute the respective drive-side (driving-side) tooth surfaces 8 and 9, and the concave tooth surface of the ring gear 2 and the convex tooth surface of the pinion gear 3 constitute the respective coast-side (driven-side) tooth surfaces 10 and 11. Due to such a tooth surface configuration and the offset of the rotation axes, in the hypoid gear 1, the meshing points between the tooth surfaces transition in the tooth flank direction, which is referred to as the tooth surfaces sliding. In this example, on the drive-side tooth surface (convex tooth surface) 8 of the ring gear 2, in the meshing rotation with the pinion gear 3, the meshing point transitions from the tooth tip side on the radially outer side to the tooth root side on the radially inner side. In this embodiment, the rotation axis of the pinion gear 3 is arranged above the rotation axis of the ring gear 2.

[0013] FIG. 5 schematically shows the meshing state of the teeth 4 of the ring gear 2 and the teeth 5 of the pinion gear 3 in the hypoid gear 1. For example, when the driving pinion gear 3 is rotated in the direction of the arrow in the figure, the amount of lubricating oil present in the leading region of the meshing point of the teeth 4 and 5 is important. If the amount of lubricating oil in this region is sufficient, the coefficient of friction between the tooth surfaces is reduced and the transmission efficiency is improved as described above. The lubricating oil present in this region is called an oil wedge 13 from its shape, and it is desirable to appropriately determine the amount of lubricating oil in the oil wedge 13. In the hypoid gear 1 where the meshing point transitions in the tooth width direction, it is desirable to appropriately determine the amount of lubricating oil in the oil wedge 13 present in the leading region in the transition direction of this meshing point.

[0014] In this embodiment, the amount of lubricating oil between the tooth surfaces was analyzed using the particle method. As is well known, the particle method captures a fluid, for example, as an array of particles, obtains the acceleration of each particle from the Navier-Stokes equation, and successively updates the velocity of the particles moved by that acceleration to obtain the movement of the fluid, that is, the flow. However, the particles do not represent a substance like a water droplet, but rather represent calculation points, similar to the lattice points of the lattice method. This particle method has several merits, but it is particularly effective for tracking a state where fluid droplets are widely scattered, and the analysis results can be intuitively visualized. By extracting (and making static) the fluid flow from the meshing rotation state of the gears and obtaining the amount of particles of the lubricating oil present in the aforementioned oil wedge 13, the amount of lubricating oil in the oil wedge 13 can be calculated. In this embodiment, a fluid analysis application based on the particle method was installed in an arithmetic processing device such as a personal computer to calculate the amount of lubricating oil between the tooth surfaces in the hypoid gear 1. For calculating the amount of lubricating oil, the gear specifications of the hypoid gear 1, that is, the specifications of the ring gear 2 and the pinion gear 3 and the specifications of the lubricating oil are used. According to this fluid analysis application, the flow of the lubricating oil can be dynamically viewed, for example, on the monitor of a personal computer in conjunction with the meshing rotation of the hypoid gear 1. Note that in this specification, the lubricating fluid of the gear mechanism is represented as lubricating "oil", but it is obvious that this lubricating oil also includes lubricating fluids that do not correspond to oils and fats such as petroleum.

[0015] In this embodiment, the lubricating oil amount calculation region 12 in FIG. 1 is set as follows. Since the meshing points in the meshing rotation of the ring gear 2 and the pinion gear 3 are known from the specifications of the gears, by making the backlash between the tooth 4 of the ring gear 2 and the tooth 5 of the pinion gear 3 approach zero at this meshing point, a contact line C can be obtained where both teeth 4 and 5 are considered to be in almost contact. The curved line described on the drive side tooth surface 8 of the ring gear 2 in FIG. 2 is an example of the contact line C and passes through the meshing point at a specific time. Such a contact line C can be obtained approximately continuously (substantially discretely at a predetermined sampling period) for each meshing point. Therefore, this contact line C is moved forward in the meshing point transition direction by a predetermined amount, such as after a predetermined time, as shown by C' in FIG. 3, and a surface formed by its movement locus (in this case, a part of the drive side tooth surface 8 of the ring gear 2) is obtained. The surface formed by this contact line movement locus (hereinafter defined as the movement locus contact surface F) is given a thickness in the rotation direction of the ring gear 2. In this example, the volume portion formed by rotating the movement locus contact surface F by a predetermined angle around the rotation axis of the ring gear 2 is taken as the lubricating oil amount calculation region 12 shown in FIG. 1.

[0016] Therefore, this lubricating oil amount calculation region 12 is moved forward in the meshing point transition direction while its position and shape change with the transition of the meshing point. In this embodiment, the lubricating oil amount calculation region 12 is moved in accordance with the locus of the tool for forming the tooth 4 of the ring gear 2. FIG. 6 schematically shows a face milling type ring gear manufacturing process in which the cutter head 14 is rotated to form teeth (tooth grooves) while the workpiece (blank of the ring gear 2) is fixed. The movement of the contact point of the blade of the cutter head 14 is simpler in the state where only the cutter head 14 is rotated with the ring gear 2 (blank) fixed than in the state where the ring gear 2 and the pinion gear 3 are meshing and rotating with each other. Therefore, in this example, the lubricating oil amount calculation region 12 in FIG. 1 is moved in accordance with the movement of the contact point of the blade of this cutter head 13. When moving, the lubricating oil amount calculation region 12 formed by the movement locus contact surface F from the moved contact line C to the contact line C' moved forward by a predetermined amount in the meshing point transition direction is set.

[0017] In the fluid analysis application using the particle method described above, the flow of lubricating oil in the meshing rotation of the ring gear 2 and the pinion gear 3 can be obtained. Therefore, as the meshing point transitions, if the volume portion from the contact line C at that time to the contact line C' ahead by a predetermined amount is set as the lubricating oil amount calculation region 12, the lubricating oil amount in the oil wedge 13 in the lubricating oil amount calculation region 12 can be obtained (calculated). An example of the lubricating oil amount in the oil wedge 13 thus obtained, that is, in the lubricating oil amount calculation region 12, is shown in FIG. 7. The horizontal axis in this figure is the phase of the meshing point, which is equivalent to the rotation angle of the ring gear 2 in the meshing rotation with the pinion gear 3. In this example, as the meshing point transitions, it was possible to obtain a tendency for the lubricating oil amount to increase at the center in the tooth width direction and then decrease.

[0018] Next, a second embodiment of the method for calculating the lubricating oil amount of the gear of the present invention will be described with reference to FIG. 4. Also in this embodiment, as in the first embodiment, the flow of lubricating oil is obtained by a fluid analysis application using the particle method installed in an arithmetic processing device such as a personal computer, but the method for calculating the lubricating oil amount obtained by the application is different from that of the first embodiment. Although details will be described later, in this embodiment, an oil film of a predetermined thickness uniformly exists in the lubricating oil amount calculation region 12 to be described later, and as the contact line C similar to that in the first embodiment moves in the tooth width direction, this oil film is scraped and an oil wedge 13 is formed. However, when the contact line C passes through the center in the tooth width direction, gaps are formed at the tip and root portions of the teeth in the meshing portion of the tooth 4 of the ring gear 2 and the tooth 5 of the pinion gear 3 calculated from the gear specifications, and the gaps gradually become larger, and the lubricating oil scraped through these gaps leaks and the lubricating oil amount gradually decreases.

[0019] The lubricating oil amount calculation region 12 shown in Fig. 4 is set by giving a predetermined thickness in the rotational direction of the ring gear 2 to the entire drive-side tooth surface 8 of the ring gear 2. In this lubricating oil amount calculation region 12, there is an oil film with a uniform thickness of, for example, 10 μm, and the contact line C passing through the meshing point scrapes it while gradually moving in the transition direction of the meshing point to form an oil wedge 13. Therefore, as the contact line moves in the tooth trace direction, the amount of lubricating oil accumulated in the oil wedge 13 increases. However, for example, in the meshing of the teeth 4 of the ring gear 2 and the teeth 5 of the pinion gear 3 obtained from CAD data, from the time when the contact line C passes through the center portion in the tooth trace direction, clearances (gaps) are formed at the tooth tip portion and the tooth root portion, and furthermore, since the clearances gradually increase, the scraped lubricating oil leaks through the clearances, and the amount of lubricating oil gradually decreases. The amount of lubricating oil in the oil wedge 13 obtained by this lubricating oil amount calculation method is also equivalent to that in Fig. 7 described above. The actual amount of lubricating oil in the oil wedge 13 is the value obtained by subtracting the amount of lubricating oil of the oil film with a uniform thickness initially set from the amount of lubricating oil accumulated from the start of meshing.

[0020] Thus, according to the lubricating oil amount calculation method for the gears of these embodiments, a lubricating oil amount calculation region 12 for calculating the lubricating oil amount is set in the vicinity region along the drive side tooth surface 8 of the ring gear 2 and not protruding from the drive side tooth surface 8, and a contact line C between the tooth 4 of the ring gear 2 and the tooth 5 of the pinion gear 3 passing through the meshing point is set. Using the specifications of the ring gear 2 and the pinion gear 3 and the specifications of the lubricating oil, and moving the lubricating oil amount calculation region 12 or the contact line C as the meshing point transitions, the lubricating oil amount within the lubricating oil amount calculation region 12 is calculated by the fluid analysis means of the arithmetic processing unit. Specifically, when setting the lubricating oil amount calculation region 12 corresponding to the contact line C in the forward direction of the meshing point transition direction, if the lubricating oil amount calculation region 12 is moved as the meshing point transitions, the lubricating oil amount in the forward region in the meshing point transition direction can be obtained. When setting the lubricating oil amount calculation region 12 over the entire tooth surface, if the contact line C is moved within the lubricating oil amount calculation region 12, the lubricating oil amount formed by the contact line C scraping the oil film within the lubricating oil amount calculation region 12 can be obtained as the lubricating oil amount in the forward region in the meshing point transition direction. Thereby, the lubricating oil amount involved in the meshing from now on can be obtained, and thus the lubricating oil amount between the tooth surfaces of the hypoid gear 1 to be evaluated can be appropriately obtained.

[0021] Further, a surface formed by moving the contact line C between the ring gear 2 and the pinion gear 3 a predetermined amount in the forward direction of the meshing point transition direction along the tooth surface is given a thickness in the rotation direction of the ring gear 2 to set the lubricating oil amount calculation region 12, and this lubricating oil calculation region 12 is moved as the meshing point transitions to calculate the lubricating oil amount within the lubricating oil calculation region 12. Thereby, the lubricating oil amount in the forward region in the meshing point transition direction, that is, the lubricating oil amount of the oil wedge 13, can be appropriately obtained.

[0022] Further, the entire drive side tooth surface 8 of the ring gear 2 is given a predetermined thickness in the rotation direction of the ring gear 2 to set the lubricating oil amount calculation region 12, and the lubricating oil amount obtained by the contact line C between the ring gear 2 and the pinion gear 3 scraping the uniformly thick oil film within the lubricating oil calculation region 12 as the meshing point transitions is calculated. Thereby, the lubricating oil amount in the forward region in the meshing point transition method direction, that is, the lubricating oil amount of the oil wedge 13, can be appropriately obtained.

[0023] The lubricating oil amount calculation method for the gear according to the embodiment has been described above. However, the present invention is not limited to the configuration described in the above embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the above embodiment, only the case where the lubricating oil amount calculation region 12 is set on the drive side tooth surface 8 of the ring gear 2 has been described, but this lubricating oil amount calculation region 12 can also be set in the same manner for the tooth surface of the pinion gear 3.

[0024] In addition to the aforementioned particle method, a well-known lattice method (mesh method) or the like can also be used as the fluid analysis means by the arithmetic processing device.

Explanation of Reference Numerals

[0025] 1 Hypoid gear 2 Ring gear 3 Pinion gear 4 (Teeth of the ring gear) 8 (Drive side) Tooth surface

Claims

1. A gear lubricating oil quantity calculation method for a gear in which the meshing point of the teeth of a ring gear and a pinion gear transitions as they rotate in mesh, the method calculating the amount of lubricating oil present between the tooth surfaces of the ring gear and the pinion gear in the leading region in the transition direction of the meshing point, comprising: setting a lubricating oil quantity calculation region for calculating the lubricating oil quantity along a tooth surface of either the ring gear or the pinion gear and within a vicinity region that does not protrude from the tooth surface; setting a contact line between the tooth of the ring gear and the tooth of the pinion gear passing through the meshing point; and calculating the lubricating oil quantity within the lubricating oil quantity calculation region by fluid analysis means of an arithmetic processing unit while moving the lubricating oil quantity calculation region or the contact line in accordance with the transition of the meshing point, using the specifications of the ring gear and the pinion gear and the specifications of the lubricating oil. A gear lubricating oil quantity calculation method characterized by the above.

2. The lubricating oil quantity calculation region is set by giving a thickness in the rotational direction of the gear to a surface formed by moving the contact line a predetermined amount in the leading direction of the transition direction along the tooth surface. The lubricating oil quantity within the lubricating oil quantity calculation region is calculated by fluid analysis means of the arithmetic processing unit while moving the lubricating oil quantity calculation region in accordance with the transition of the meshing point. The gear lubricating oil quantity calculation method according to claim 1, characterized by the above.

3. The lubricating oil quantity calculation region is set by giving a predetermined thickness in the rotational direction of the gear to the entire tooth surface. The lubricating oil quantity obtained by the contact line scraping together a lubricating oil film of uniform thickness within the lubricating oil quantity calculation region in accordance with the transition of the meshing point is calculated by fluid analysis means of the arithmetic processing unit. The gear lubricating oil quantity calculation method according to claim 1, characterized by the above.

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