stepped pinion

Abstract

The present application discloses a stepped pinion capable of making the engagement of tooth surfaces appropriate regardless of the direction of the transmitted torque and simple in structure. In the stepped pinion, a large-diameter gear portion and a small-diameter gear portion are arranged at a prescribed interval in the axial direction of a rotation shaft. The large-diameter gear portion has a disc portion and a rim portion extending from the outside in the radial direction of the rotation shaft. A reinforcing member is arranged in the rim portion to support the portion extending from the disc portion toward one side in the axial direction. The reinforcing member is fixed in a state of extending to the outside in the radial direction of the rotation shaft. The inner peripheral surface of the rim portion is brought into abutment with the front end portion to limit the first inclination of the rim portion and allow the second inclination of the rim portion in the direction opposite to the first inclination in which the inner peripheral surface of the rim portion is separated from the front end portion.

Description

Technical Field

[0001] This utility model relates to a stepped pinion with gears of different pitch circle diameters arranged on the same axis. Background Technology

[0002] Patent Document 1 describes an example of a reinforcing structure for a gear component having a large-diameter gear portion and a small-diameter gear portion, respectively, that are helical gears. The gear component described in Patent Document 1 is formed from a resin material such as injection-molded plastic, and its walls are thinned to achieve high-precision molding. When this type of gear rotates, the thrust causes gear twisting in the direction of decreasing meshing width of the tooth surface, potentially leading to changes in gear rotation speed or tooth surface wear. To avoid this adverse situation, a metal reinforcing member is mounted on at least one side of the gear component described in Patent Document 1. This reinforcing member is a circular metal plate component with an outer diameter the same as the inner diameter of the large-diameter gear portion, and is mounted to the back of the gear component by multiple bolts. Furthermore, reinforcing members with the same structure can also be mounted on the surface of the gear component. In this case, the center of gravity of the gear component in the axial direction is homogenized relative to the center of rotation of the gear component, and the moment of inertia of each reinforcing member is applied to the gear component, thus enabling the gear component to rotate stably.

[0003] Furthermore, Patent Document 2 describes a gear that limits gear deformation caused by the thrust generated due to its helical nature by providing a reinforcing structure. In this gear, helical teeth are formed on the outer circumferential surface of the cylindrical rim portion, and a disc portion (or flange) is integrally formed approximately at the center of the inner circumferential side of the rim portion in the width direction. If a load in the thrust direction accompanying the transmission torque is applied to the helical teeth, the gear (i.e., the rim portion) tilts relative to a direction parallel to the axis of rotation. Therefore, in the gear described in Patent Document 2, a reinforcing member is mounted along both sides of the disc portion (or flange), and the front end (the end on the outer circumferential side) of the reinforcing member abuts against the inner circumferential surface of the rim portion, thereby limiting the tilting of the gear.

[0004] Patent Document 1: Japanese Patent Application Publication No. 8-74971

[0005] Patent Document 2: Japanese Patent Application Publication No. 2007-040399 Utility Model Content

[0006] When a helical gear meshes with an opposing gear to transmit torque, twisting or tilting occurs due to the load in the direction of the thrust that causes the reaction force. In the gears described in Patent Document 1 or Patent Document 2, the twisting or tilting of the cylindrical portion, which is essentially the cylindrical portion, is limited by a reinforcing member disposed on its inner circumference supporting a toothed cylindrical portion formed on its outer circumference. The reinforcing member is mounted on both sides of a so-called disk portion connected to the inner circumference of the cylindrical portion. Furthermore, particularly in the gear described in Patent Document 2, tilting towards the left and right sides that sandwich the disk portion can be limited or suppressed by reinforcing members similarly provided on both sides.

[0007] The load acting on the thrust direction of a helical gear varies depending on the direction of the torque transmitted by the gear (the forward rotation direction and the opposite reverse rotation direction), and there are often cases where the frequency of torque transmission in the forward rotation direction and the frequency of torque transmission in the opposite reverse rotation direction are different. In such a gear configuration, the proper meshing state cannot be ensured in the structures described in Patent Document 1 or Patent Document 2, thus generating noise or vibration, and potentially reducing gear durability. Specifically, in helical gears, twisting or tilting occurs due to the load accompanying the thrust direction of torque transmission; therefore, such deformation is sometimes taken into account when setting the tooth surface shape or assembling the gear. In this case, the deformation considered is a high-frequency deformation under normal operating conditions; in terms of tilting, it is tilting to either the left or right. Therefore, in the normal operating region, the tooth surface is set or the gear is assembled considering this deformation, thus optimizing the tooth meshing.

[0008] However, in the structures described in Patent Document 1 or Patent Document 2, since the structure restricts or suppresses tilting or twisting in both left and right directions, in a so-called emergency state where the direction of the transmitted torque is to be reversed, the twisting or tilting exceeds "0" and twists or tilts in the opposite direction. As a result, in the case of deformation not considered for the setting or assembly of the tooth surface, the amount of twisting or tilting that produces proper engagement (the amount of twisting or tilting when the torque is in the unloaded state of "0") increases beyond the opposite side compared to the degree of twisting or tilting observed from the state of proper engagement. That is, the error from proper engagement increases, and in the case of reversal of the transmitted torque, noise or vibration may worsen. Furthermore, in the structures described in Patent Document 1 or Patent Document 2, reinforcing members are mounted on both sides of the disk, so the outer periphery of these reinforcing members supports the part of the cylindrical rim of the essentially gear closest to the disk, i.e., the tilted root portion. Since the root portion represents the area with the least displacement in the event of tilting, significant tilting may be permissible if machining or assembly errors occur between the inner diameter of the rim and the outer diameter of the reinforcing component. Therefore, high precision is required in the machining or assembly of the reinforcing component, and its manufacturability or assemblability is not necessarily good.

[0009] This utility model was developed in response to the aforementioned technical issues, and its purpose is to provide a stepped pinion that can appropriately optimize the meshing on the tooth surface regardless of the direction of the transmitted torque and has a simple structure.

[0010] This utility model relates to a stepped pinion, characterized in that it comprises: a large-diameter gear portion having helical teeth on its outer circumferential surface; and a small-diameter gear portion having a smaller diameter than the large-diameter gear portion and having other helical teeth on its outer circumferential surface, and being arranged at predetermined intervals in the axial direction on a predetermined rotation axis. The large-diameter gear portion has a disc portion extending outward in the radial direction from the rotation axis, and a cylindrical rim portion extending from the outer circumferential end of the disc portion to both sides in the axial direction of the rotation axis and having the helical teeth formed on its outer circumferential surface. A reinforcing member is provided in the rim portion to support the portion extending from the disc portion to one side in the axial direction from the inner circumferential side. The reinforcing member is configured to be fixed in a state extending outward in the radial direction of the rotation axis, and to abut against the front end of the rim portion to restrict a first tilt of the rim portion and allow a second tilt in the opposite direction to the first tilt that separates the inner circumferential surface of the rim portion from the front end portion.

[0011] Utility Model Effect

[0012] According to this invention, when the large-diameter gear portion is tilted to one side in the axial direction of its rotation axis, further tilting of the large-diameter gear portion is limited by one end of the reinforcing member abutting against the inner circumferential surface of the rim portion of the large-diameter gear portion. Furthermore, if a load acts on the large-diameter gear portion in the opposite direction of the transmitted torque, causing it to tilt to the other side in the axial direction, the rim portion tilts to the other side and separates from the reinforcing member because there is no restriction based on the reinforcing member. By taking this tilting of the large-diameter gear portion to the other side as a normal state, and setting the shape or assembly of the tooth surface according to this tilt, the meshing of gears in the normal state can be properly optimized, and vibration, noise, or a decrease in durability can be avoided or suppressed. Conversely, when the torque acts in the opposite direction to the so-called normal state, causing the large-diameter gear portion to tilt to that side, the outer circumferential end of the reinforcing member abuts against the inner circumferential surface of the rim portion, limiting the tilting of the rim portion to that side. That is, since the tilting of the rim portion is limited from the proper meshing state by the reinforcing member, the deviation from the proper meshing state, i.e., the meshing error, is reduced. As a result, even if the direction of the torque is reversed, the meshing state of the gears can be properly optimized, or deviations or errors from the proper meshing state can be reduced to suppress noise, vibration, or a decrease in durability. Attached Figure Description

[0013] Figure 1 This is a perspective view showing the structure of a planetary gear mechanism using a stepped pinion in an embodiment of the present invention.

[0014] Figure 2 This is a diagram showing the structure of the stepped pinion in an embodiment of the present invention. Figure 2 (a) is a cross-sectional view along the axis of rotation of the stepped pinion. Figure 2 (b) is a side view of the stepped gear when viewed from the front.

[0015] Figure 3 (a) is a schematic diagram showing the tilting state of the large-diameter gear section during power operation. Figure 3 (b) is a schematic diagram showing the area of ​​tooth contact on the tooth surface.

[0016] Figure 4 (a) is a schematic diagram showing the tilting state of the large-diameter gear section during regeneration. Figure 4 (b) is a schematic diagram showing the area of ​​tooth contact on the tooth surface. Detailed Implementation

[0017] The present invention will be described with reference to the illustrated embodiments. Furthermore, the embodiments described below are merely examples embodying the present invention and are not intended to limit the scope of the invention.

[0018] Figure 1 The diagram shows an example of a planetary gear mechanism P for a stepped pinion 1 used in an embodiment of this invention. The planetary gear mechanism P can be installed, for example, in vehicles such as hybrid vehicles, to distribute the torque of a motor or engine, which serves as a driving force source, to the drive wheels and designated output components. Figure 1 As shown, the planetary gear mechanism P includes: a sun gear 2; a ring gear 3 disposed concentrically with the sun gear 2; and multiple stepped pinions 1 disposed around the sun gear 2. The sun gear 2 is an external gear with multiple helical teeth formed on its outer circumferential surface. The ring gear 3 is an internal gear with multiple helical teeth formed on its inner circumferential surface. Each stepped pinion 1 includes a large-diameter gear portion 1a formed at one end and a small-diameter gear portion 1b formed on a pinion shaft Sp, which is a small-diameter rotational axis extending from the large-diameter gear portion 1a along the rotation axis. Multiple helical teeth are formed on the outer circumferential surfaces of both the large-diameter gear portion 1a and the small-diameter gear portion 1b. The large-diameter gear portion 1a of each stepped pinion 1 meshes with the sun gear 2, and the small-diameter gear portion 1b meshes with the ring gear 3.

[0019] A motor (i.e., motor generator), not shown, with a power generation function, is connected to the sun gear shaft 2a of the sun gear 2. When the motor connected to the sun gear 2 functions as a driving force source, i.e., when the motor is in operation, the sun gear 2 rotates due to the output torque of the motor. In this state, the stepped pinion 1 inevitably tilts due to the thrust caused by the meshing between these helical teeth. In particular, the large diameter gear portion 1a of the stepped pinion 1, which meshes directly with the sun gear 2, tilts relative to the pinion shaft Sp. Therefore, in the planetary gear mechanism P, at least the large diameter gear portion 1a of the stepped pinion 1 and the sun gear 2 are adjusted to optimize the meshing between these helical teeth when these gears are tilted during motor operation.

[0020] As described above, the motor connected to the sun gear 2 has a power generation function. Specifically, when the output shaft of the motor rotates due to an external force, the motor functions as a generator. However, when the motor connected to the sun gear 2 functions as a generator, i.e., during motor energy regeneration, the thrust acting between the helical teeth of the sun gear 2 and the helical teeth of the stepped pinion 1 acts in the opposite direction to the motor's power operation. Therefore, during motor regeneration, the large-diameter gear portion 1a of the stepped pinion 1 tilts relative to the pinion shaft Sp in the opposite direction to the tilting direction of the sun gear 2 (the second tilt in this invention). As a result, the helical teeth of the large-diameter gear portion 1a abut against the helical teeth of the sun gear 2, and the helical teeth of both may wear unevenly, or generate noise or vibration that is amplified.

[0021] Here, if we explain the inclination of the large-diameter gear section 1a, it will be as follows: Figure 2As shown, the large-diameter gear section 1a has a disc-shaped portion (or flange) D extending radially from the pinion shaft Sp, and a cylindrical rim portion R integrally formed with the outer periphery of the disc-shaped portion D. Helical teeth are formed on the outer peripheral surface of the rim portion R. The rim portion R extends axially from the disc-shaped portion D. Furthermore, the rim portion R is parallel to the pinion shaft Sp, which is the unloaded state or design state. The tilting of the large-diameter gear section 1a refers to a state where the rim portion R is not parallel to the pinion shaft Sp or its rotational axis, and one end in the tooth pattern direction is displaced more inwardly than the other end. This deformation occurs at the point of meshing with the sun gear 2 or the ring gear 3.

[0022] To prevent the large-diameter gear portion 1a of the stepped pinion 1 from tilting (the first tilt in this invention) during regeneration of the motor, in an embodiment of this invention, a [missing information - likely a type of gear] is provided between the large-diameter gear portion 1a and the small-diameter gear portion 1b of the stepped pinion 1. Figure 2 Support plate 4 is shown. Figure 2 (a) is a schematic cross-sectional view along the axis of rotation of the stepped pinion 1 on which the support plate 4 is provided. Figure 2 (b) is a schematic front view of the stepped pinion 1 with the support plate 4. Figure 2 As shown, the support plate 4 is a rectangular plate component, positioned in the large-diameter gear section 1a with its inner circumferential surface facing one end in the axial direction, and fixed to the pinion shaft Sp. This support plate 4 is equivalent to the reinforcing component in this invention.

[0023] If we describe the support plate 4 in more detail, the radial length of the stepped pinion 1 of the support plate 4 is the length of the front end in contact with the inner circumferential surface of the rim R, which does not tilt under the aforementioned design conditions. Figure 2 The four support plates 4 shown are fixed by inserting their base ends into the grooves 1d formed in the pinion shaft Sp. Furthermore, the mechanism for fixing the support plates 4 to the pinion shaft Sp can be appropriately selected, the key being that the outer peripheral end 4b of the support plate 4 contacts the inner peripheral surface of the rim R, and in particular, stress is avoided.

[0024] Thus, the inner peripheral end 4a of the support plate 4 is fitted into the groove 1d formed on the outer peripheral surface of the small diameter gear portion 1b, and the outer peripheral end 4b of the support plate 4 is not fixed relative to the inner peripheral surface of the rim portion of the large diameter gear portion 1a. Figure 2 In the example shown, the groove 1d is formed at four locations on the outer peripheral surface of the small diameter gear part 1b at equal intervals in the circumferential direction. Therefore, four support plates 4 are arranged between the large diameter gear part 1a and the small diameter gear part 1b on the pinion shaft Sp.

[0025] The states of the stepped pinion 1 and the sun gear 2 during the operation of the planetary gear mechanism P are shown in the figure. Figure 3 and Figure 4 middle. Figure 3 (a) indicates the tilting state of the large-diameter gear section 1a of the sun gear 2 and the stepped pinion 1 when powered by the motor. For example... Figure 3 As indicated by the arrow in (a), during motor-driven operation, the thrust acts between the helical teeth of the sun gear 2 and the helical teeth of the stepped pinion 1 in the direction where the large diameter gear portion 1a of the stepped pinion 1 is in close contact with the sun gear 2 (in...). Figure 3 In (a), the large-diameter gear portion 1a is tilted to the lower right at the meshing point with the sun gear 2 (the second tilt in this invention). As described above, the outer peripheral end 4b of the support plate 4 only contacts the inner peripheral surface of the rim R of the large-diameter gear portion 1a and is not fixed. Therefore, due to the thrust generated by the meshing of the sun gear 2 and the large-diameter gear portion 1a, the large-diameter gear portion 1a is allowed to tilt in a direction that separates radially outward from one end along the axial direction of the large-diameter gear portion 1a toward the outer peripheral end 4b of the support plate 4.

[0026] The helical teeth of the sun gear 2 and the large diameter gear section 1a are formed to optimize meshing when these gears are tilted during motor power operation. Therefore, this optimized meshing of the sun gear 2 and the large diameter gear section 1a can be maintained during power operation. For example, as... Figure 3 In (b), the tooth contact area A is schematically surrounded by an ellipse, and tooth contact occurs at almost the center of the tooth surface F of the sun gear 2 and the large diameter gear 1a.

[0027] Figure 4 (a) indicates the tilting state of the large-diameter gear section 1a of the sun gear 2 and the stepped pinion 1 during regeneration. For example... Figure 4 As indicated by the arrow in (a), during regeneration, between the helical teeth of the sun gear 2 and the helical teeth of the stepped pinion 1, there is an action that pushes the stepped pinion 1 towards... Figure 4 The thrust tilted to the left in (a). As a result, the large-diameter gear 1a is inclined towards one end in the axial direction ( Figure 4 (a) The left side is inclined in the direction of radial displacement inward (the first inclination in this invention). Therefore, in this state, the inner circumferential surface of the rim R abuts against the outer circumferential end of the support plate 4, thereby limiting further inclination of the large-diameter gear portion 1a of the stepped pinion 1. That is, during regeneration, the large-diameter gear portion 1a intends to incline in the opposite direction to the aforementioned power operation, but its inclination is limited by the support plate 4. Therefore, deviation from the meshing state appropriate for the inclination during power operation is suppressed, and even if meshing error occurs, it is maintained as a small error. For example, as Figure 4 (b) schematically surrounds the tooth contact area A with an ellipse. Although it is off from the center of the tooth surface F, the deviation is small, and the meshing between the helical teeth of the sun gear 2 and the large diameter gear 1a will not be particularly bad.

[0028] Thus, according to the embodiment of this utility model, when powered by the motor connected to the sun gear 2, the large-diameter gear portion 1a is allowed to tilt in a direction that separates radially outward from one end of the support plate 4 in the axial direction. Therefore, during power operation, the meshing between the helical teeth of these gears, which are pre-optimized taking into account the tilt of the sun gear 2 and the large-diameter gear portion 1a, can be maintained.

[0029] On the other hand, during regeneration by the motor, the outer peripheral end of the support plate 4 abuts against the inner peripheral surface of one end of the rim portion R in the axial direction of the large diameter gear portion 1a, thereby suppressing the tilting of the stepped pinion 1 or its large diameter gear portion 1a. Therefore, even during regeneration, as described above, the meshing between the helical teeth of the sun gear 2 and the large diameter gear portion 1a does not particularly deteriorate, thus preventing uneven wear of these gears and suppressing noise or vibration of the planetary gear mechanism P.

[0030] On the other hand, in this embodiment of the invention, a support plate 4, serving as a reinforcing member supporting the inner circumference of the large-diameter gear section 1a, is provided on the pinion shaft Sp. Therefore, the portion supporting the large-diameter gear section 1a via the support plate 4 can be set as the front end in the axial direction of the rim section R. Since this front end is the portion where the displacement increases when the large-diameter gear section 1a is tilted, the error in the length of the support plate 4 (the dimension from the pinion shaft Sp to the front end) has little impact on the tilt angle when supporting the large-diameter gear section 1a. Therefore, the tilt of the large-diameter gear section 1a or the rim section R can be controlled with high precision.

[0031] Furthermore, this utility model is not limited to the above-described embodiments, and appropriate modifications can be made within the scope of the structure described in the claims. For example, four support plates 4 are used in the above embodiments, but the number of support plates can be set to an appropriate number as needed, or they can be circular plates instead of rectangular plates, in which case there can be only one support plate.

[0032] Symbol Explanation

[0033] 1-Stepped pinion, 1a-Large diameter gear section, 1b-Small diameter gear section, 1d-Slot, 2-Sun gear, 2a-Sun gear shaft, 3-Ring gear, 4-Support plate (reinforcing component), 4a-Inner peripheral end, 4b-Outer peripheral end, A-Tooth contact area, D-Disc section, F-Tooth surface, P-Planetary gear mechanism, R-Rim section, Sp-Pinary gear shaft (rotation shaft).

Claims

1. A stepped pinion, characterized in that, It comprises: a large-diameter gear portion having helical teeth on its outer circumferential surface; and a small-diameter gear portion having a smaller diameter than the large-diameter gear portion and having other helical teeth on its outer circumferential surface, and arranged at predetermined intervals in the axial direction on a predetermined axis of rotation. The large-diameter gear portion has a disk portion extending outward in the radial direction from the axis of rotation, and a cylindrical rim portion extending to both sides from the outer peripheral end of the disk portion in the axial direction of the axis of rotation, and having the helical teeth formed on its outer peripheral surface. A reinforcing member is provided in the rim portion to support a portion extending from the disk portion toward one side in the axial direction. The reinforcing member is configured to be fixed in a state extending outward in the radial direction of the rotation axis, and to abut the inner circumferential surface of the rim portion against the front end portion to limit the first tilt of the rim portion and allow a second tilt in the opposite direction to the first tilt that separates the inner circumferential surface of the rim portion from the front end portion.

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