In-wheel type driving device

Abstract

To provide an in-wheel type driving device which enables components to be used for several models and can achieve reduction of costs.SOLUTION: In an in-wheel type driving device, a first pinion gear 12b is formed in a cylindrical shape. A carrier 13 has: a cylindrical drum part 13a which covers the first pinion gear 12b; and a pin support part 13c which rotatably supports a pinion pin 12a at the inner periphery side of the first pinion gear 12b. A minimum interval C between an inner peripheral surface of the drum part 13a and an outer peripheral surface of the pin support part 13c is set to an interval that allows a plurality of first pinion gears 12b having different tooth tip diameters to be selectively provided at the pinion pin 12a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive unit that is incorporated inside the wheels of various running bodies such as vehicles that run by rotating the wheels, and transmits driving force and braking force for running to the wheels, and more particularly to an in-wheel type drive unit in which a reduction mechanism is constituted mainly by a stepped pinion type planetary gear mechanism. [Background technology]

[0002] An example of this type of drive device is described in Patent Document 1. The drive device described in Patent Document 1 is a device that is miniaturized so that a motor, a reduction mechanism, and a brake device can be accommodated on the inner periphery side of a wheel, and a reduction mechanism is arranged between the wheel hub and the motor arranged inside it. The reduction mechanism is mainly configured with a planetary gear mechanism equipped with a so-called stepped pinion in which a large-diameter pinion gear and a small-diameter pinion gear are connected by a pinion pin. A ring gear that meshes with the small-diameter pinion gear is arranged on the inner periphery side of the motor so that a part of it overlaps in the radial direction. A central shaft arranged concentrically with the ring gear is arranged from the motor side toward the wheel hub side, and a rotor in the motor is connected to one end of the central shaft. In addition, a sun gear is formed on the other end of the central shaft, and a large-diameter pinion gear meshes with the sun gear. Therefore, the sun gear is an input element in the planetary gear mechanism. The carrier that holds the stepped pinion has a flange portion to which the pinion pin is attached and an output shaft portion that is located on the same axis as the central shaft and extends further toward the wheel hub from the tip side of the central shaft. In other words, the carrier is the output element of the planetary gear mechanism, and the wheel hub is connected to the output shaft portion that is integrated with the carrier.

[0003] The stator of the motor is mounted inside a case that serves as a fixed part that is mounted to a vehicle body or the like, and the case has a cylindrical part that covers the outer periphery of the flange part of the carrier and the outer periphery of the output shaft part. The ring gear has a drum part that covers the outer periphery of the large-diameter pinion gear, and is fixed by connecting the drum part to the cylindrical part, thereby serving as a fixed element of the planetary gear mechanism. Furthermore, a bearing is inserted into the inner periphery of the part of the cylindrical part that covers the outer periphery of the output shaft part, and the cylindrical shaft part that is part of the wheel hub is rotatably supported by the bearing. The output shaft part is spline-fitted to the inner periphery of the cylindrical shaft part. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-147177 A Summary of the Invention [Problem to be solved by the invention]

[0005] The drive device described in the above-mentioned Patent Document 1 mainly uses a stepped pinion type planetary gear mechanism as a transmission mechanism, and therefore a large reduction ratio can be set with a small number of components, thereby achieving a compact overall device. In addition, the relative positional relationship between the motor and the planetary gear mechanism, the configuration for fixing the ring gear, and other factors have been devised to achieve a compact overall device. On the other hand, there is a lack of freedom in the configuration, and therefore there is room for improvement in terms of versatility and cost reduction.

[0006] That is, in a stepped pinion type planetary gear mechanism, the pinion gear meshing with the sun gear and the pinion gear meshing with the ring gear are gears with different pitch circle diameters (or numbers of teeth), so if one of the pinion gears and the gear meshing with it are left unchanged and the other pinion gear and the gear meshing with it are both replaced with other gears, the gear ratio as a planetary gear mechanism (reduction ratio as a reduction mechanism) can be changed. In other words, parts can be shared between planetary gear mechanisms with different gear ratios, or if configured as a reduction mechanism, it may be easier to change the reduction ratio.

[0007] Conventional drive devices using a stepped pinion type planetary gear mechanism, including the drive device described in Patent Document 1, are not configured to utilize the above-mentioned characteristics of the stepped pinion type planetary gear mechanism, and therefore there is room for improvement in terms of reducing costs through the use of standardized parts.

[0008] This invention has been made against the background of the above circumstances, and aims to provide an in-wheel type drive device that is not only easily miniaturized for incorporation into a wheel, but also enables cost reduction through the use of standardized parts. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a stepped pinion type planetary gear mechanism disposed on the inner periphery of a wheel on which a tire is mounted, the planetary gear mechanism comprising: a sun gear driven by a motor; a first pinion gear meshed with the sun gear; a second pinion gear having a smaller diameter than the first pinion gear and integrated with the first pinion gear on the same axis; a carrier which rotates by rotatably holding a pinion pin on which the first pinion gear and the second pinion gear are provided and which is connected to the wheel; an in-wheel type drive device having a first pinion gear and a ring gear arranged concentrically with a housing to which the motor is attached and fixed to a housing to which the motor is attached, wherein the first pinion gear is formed cylindrically, the carrier has a cylindrical drum portion covering the first pinion gear and a pin support portion rotatably supporting the pinion pin on the inner side of the first pinion gear, and the minimum gap between the inner surface of the drum portion and the outer surface of the pin support portion is set so that a plurality of first pinion gears having different tooth tip diameters can be selectively attached to the pinion pin.

[0010] In this invention, the housing has a shaft support boss portion inserted into the inner periphery of the wheel from one end side in the axial direction of the wheel, an input shaft arranged along the central axis of the wheel is rotatably supported on the inner periphery of the shaft support boss portion via a bearing, the sun gear is provided on the other end side of the input shaft in the axial direction of the wheel, and the minimum inner diameter of the shaft support boss portion for fitting the bearing therein may be greater than or equal to the tooth tip diameter of the sun gear that meshes with the first pinion gear which has the smallest tooth tip diameter.

[0011] In this invention, the carrier has a retaining piece extending radially inward from the cylindrical portion between the first pinion gear and the second pinion gear in the axial direction of the pinion pin, and the pin support portion may be integrated with the retaining piece.

[0012] In the present invention, a ratio between the number of teeth of the first pinion gear and the number of teeth of the second pinion gear may be an integer.

[0013] In this invention, the sun gear may be a separate member from the input shaft, and may be attached to the input shaft, and may be arranged parallel to the pinion pin at a predetermined axial distance from the pinion pin and have an input shaft driven by the motor, and mesh with the selected first pinion gear.

[0014] In this invention, the sun gear and the first pinion gear are arranged on the other end side in the axial direction of the wheel opposite the end side on which the motor is arranged, and an opening on the other end side of the wheel may be closed by a cover that is removable from the wheel.

[0015] In the present invention, a brake for braking the rotation of the input shaft may be provided on an end side of the input shaft opposite to the end where the sun gear is provided in the axial direction of the input shaft. Effect of the Invention

[0016] In this invention, the first pinion gear, which is a so-called large-diameter pinion gear, is formed in a cylindrical shape, and a wide space is secured between the inner peripheral surface of the cylindrical portion of the carrier on which the first pinion gear is arranged and the outer peripheral surface of the pin support portion which rotatably supports the pinion pin. Specifically, the first pinion gears having different tooth tip diameters, large and small, can be selected and arranged on the inner peripheral side of the cylindrical portion. Therefore, by using a sun gear that matches the first pinion gear, it is possible to obtain an in-wheel type drive device with a different gear ratio (or reduction ratio) without changing the ring gear, carrier, or second pinion gear. As a result, the cost of the in-wheel type drive device can be reduced by standardizing parts. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic diagram of an embodiment of the present invention. [Diagram 2] Schematic cross-sectional views showing examples of planetary pinion units having different diameters of the first pinion gear, where (a) shows an example in which a so-called large diameter first pinion gear is provided, (b) shows an example in which a so-called medium diameter first pinion gear is provided, and (c) shows an example in which a so-called small diameter first pinion gear is provided. [Diagram 3] 4 is a view of the first pinion gear and the second pinion gear as viewed in a direction along their central axes. FIG. [Figure 4] FIG. 11 is a cross-sectional view showing a schematic diagram of another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of the implementation of the present invention, and is not intended to limit the present invention.

[0019] FIG. 1 is a cross-sectional view showing a schematic view of an embodiment of an in-wheel type drive device according to the present invention, which includes a housing 3 supporting a cylindrical wheel 2 with a tire 1 mounted on the outer periphery thereof. The tire 1 is attached to a vehicle body (not shown) by supporting the housing 3 with an appropriate arm member (not shown). The housing 3 is configured to be cylindrical as a whole, and is attached to the vehicle body with its central axis substantially horizontal. The diameter of the tip end side (left side in FIG. 1) of the housing 3 gradually decreases, and this portion with a smaller diameter is an axle support boss portion 3a, which is inserted into the wheel 2 from one end side (right side in FIG. 1) in the axial direction of the wheel 2.

[0020] An output bearing 4 is fitted to the outer periphery of the portion of the shaft support boss 3a where the outer diameter is relatively large on the base end side (right side in FIG. 1). In the example shown in FIG. 1, a pair of ball bearings arranged in the axial direction are used as the output bearing 4, and more specifically, a sealed type bearing that does not leak lubricating oil to the outside is used. The wheel 2 is fitted to the outer periphery of these output bearings 4, so that the wheel 2 (tire 1) is rotatably attached to the vehicle body. The output bearings 4 are prevented from coming off in the right direction in FIG. 1 by a C-ring 5 fitted to the inner periphery of the wheel 2. A seal ring 6 (not shown) is provided on the outer periphery of the output bearing 4 on the center side in the axial direction of the wheel 2 to prevent leakage of lubricating oil.

[0021] An input bearing 7 is fitted into the inner periphery of the shaft support boss 3a (particularly the tip end side portion on the left side of FIG. 1). As shown in FIG. 1, the input bearing 7 is composed of a rolling bearing with a large outer diameter and a rolling bearing with a small outer diameter, so that the inner diameter of the shaft support boss 3a is smaller on the tip end side (left side of FIG. 1). The input bearing 7 rotatably supports an input shaft 8. The input shaft 8 is a rotating shaft for transmitting driving torque to the wheel 2 for traveling, and its central axis coincides with the central axis of the wheel 2. The inner diameter of the rolling bearing on the tip end side with a small outer diameter of the input bearing 7 is larger than the inner diameter of the rolling bearing with a large outer diameter, so that the outer diameter of the input shaft 8 is larger on the tip end side (left side of FIG. 1) than on the base end side (right side of FIG. 1) in accordance with the inner diameters of these rolling bearings. In addition, reference numeral 9 in FIG. 1 denotes a C-ring, and the input bearing 7 and the input shaft 8 are prevented from coming off in the right direction in FIG. 1 by this C-ring 9 attached to the inner peripheral surface of the shaft support boss portion 3a.

[0022] A stepped pinion type planetary gear mechanism 10 is provided as a reduction mechanism that increases and transmits torque from an input shaft 8 to wheels 2. This planetary gear mechanism 10 is a gear-type differential mechanism mainly composed of a sun gear 11 serving as an input element, a carrier 13 serving as an output element that holds a planetary pinion unit 12 so that it can rotate and revolve, and a ring gear 14 serving as a reaction element (or fixed element). The planetary pinion unit 12 is characterized by having pinion gears 12b and 12c of different diameters arranged coaxially and integrated with a single pinion pin 12a, as shown in Fig. 1.

[0023] In the example shown in Fig. 1, a sun gear 11 is provided on the tip of the input shaft 8 described above. The sun gear 11 only needs to be integral with the input shaft 8, and may be formed by cutting the tip of the input shaft 8, or may be produced as a separate member from the input shaft 8 and attached to the input shaft 8. A first pinion gear 12b having a large diameter is disposed on the outer periphery of the sun gear 11 and meshes with the sun gear 11. The first pinion gear 12b is a cylindrical external gear, and is connected to and integrated with an end of the pinion pin 12a (the end on the left side in Fig. 1) by a disk portion integrated with one end of the first pinion gear 12b in the axial direction.

[0024] The pinion pin 12a extends from the first pinion gear 12b side toward one end side in the axial direction of the wheel 2 (the right side in FIG. 1) and is parallel to the input shaft 8. A second pinion gear 12c having a smaller diameter than the first pinion gear 12b is provided at the end of the pinion pin 12a on the right side in FIG. 1. This second pinion gear 12c may be formed by machining the pinion pin 12a, or may be made as a separate member from the pinion pin 12a and attached to the pinion pin 12a.

[0025] This second pinion gear 12c meshes with a ring gear 14. The ring gear 14 is an external gear having a cylindrical shape as a whole, and is provided in a cylindrical portion of the housing 3 into which the above-mentioned output bearing 4 is fitted. The ring gear 14 only needs to be integral with the housing 3 and fixed thereto, and may be provided by cutting the housing 3 or may be assembled to the housing 3.

[0026] The planetary pinion units 12 described above are arranged at equal intervals on a circle centered on the sun gear 11, and a carrier 13 serving as an output element holds the planetary pinion units 12 so that they can rotate and revolve. In the example shown in Fig. 1, the carrier 13 has a cylindrical drum portion 13a that covers the outer periphery of the first pinion gear 12b, and is integrated with the wheel 2 by, for example, spline-fitting the drum portion 13a into the inner periphery of the wheel 2. One axial end of the drum portion 13a abuts against an end of the output bearing 4 described above, and fixes the output bearing 4 in the axial direction together with the C-ring 5 described above.

[0027] A gap is provided between the output bearing 4 and the axial end of the first pinion gear 12b. A flange-shaped retaining piece 13b is integral with the drum portion 13a of the carrier 13, passing through the gap and extending radially inward, and a pin support portion 13c is provided at the radially inner end of the retaining piece 13b. The pin support portion 13c is a portion that rotatably holds the pinion pin 12a, and is formed in a ring shape (or a cylindrical shape) so that the pinion pin 12a rotatably passes through it.

[0028] Although not shown, a bearing is fitted into the inner periphery of the pin support portion 13c, and the pinion pin 12a is rotatably supported by being tightly fitted into the inner periphery of the bearing. The portion of the pinion pin 12a that is tightly fitted into the bearing is adjacent to a disk-shaped portion that connects the first pinion gear 12b to the pinion pin 12a. Therefore, the pinion pin 12a (or the planetary pinion unit 12) is held by the carrier 13 at the middle portion of the pinion pin 12a in the axial direction, or at the portion between the first pinion gear 12b and the second pinion gear 12c. Therefore, second pinion gear 12c is supported at one end in the axial direction, so that it is in a cantilevered state, but because the point where pinion pin 12a is supported is the middle part in the axial direction, the length from the support point to the point where the load of second pinion gear 12b acts is short, and even if pinion pin 12a or second pinion gear 12c is made small (thin), a necessary and sufficient bending rigidity can be obtained. In other words, the diameter of second pinion gear 12c can be made small.

[0029] A motor 15 that drives the tire 1 (or wheel 2) to travel is attached to the housing 3. The housing 3 has a flange portion 3b at the end opposite the shaft support boss portion 3a described above in the direction of the central axis, and the motor 15 is attached to this flange portion 3b with bolts 16. Therefore, the open end of the housing 3 facing the outside is sealed by the motor 15. The motor 15 is attached to the housing 3 so that its rotating shaft (rotor shaft) 15a is positioned on the central axis of the wheel 2 or input shaft 8, and the input shaft 8 described above is connected to the rotating shaft 15a by an appropriate joint 17.

[0030] Inside the housing 3, the portion between the shaft support boss portion 3a and the motor 15 described above is an accommodation portion with an inner diameter larger than the inner diameter of the shaft support boss portion 3a, and a brake 18 is accommodated here. The brake 18 is an electrically controlled device that applies a braking force to the input shaft 8 to stop its rotation, and has a brake disc 18a and a caliper 18b that pinches the brake disc 18a to generate a frictional force for braking. The caliper 18b is fixed to the housing 3 with bolts 19, and the brake disc 18a is attached to the input shaft 8 in a state where it protrudes outward in the radial direction.

[0031] Furthermore, a cover 20 is detachably attached by bolts 21 to the open end of the wheel 2 opposite the housing 3 and motor 15, sealing the opening. A sealant 22 is interposed between the cover 20 and the carrier 13 described above, creating a liquid-tight state. Furthermore, the end of the pinion pin 12a of the planetary pinion unit 12 is abutted against the inner surface of the cover 20, thereby preventing it from coming off to the left in FIG. 1 and fixing its position.

[0032] The above-mentioned in-wheel type drive device is configured so that parts can be commonized to provide devices with different reduction ratios. The configuration for this purpose will be described with reference to FIG. 2. The example shown in FIG. 2 is an example configured so that parts other than the first pinion gear 12b and the sun gear 11 are commonized, and a large gap is provided between the inner peripheral surface of the drum portion 13a that houses the first pinion gear 12b in the carrier 13 and the outer peripheral surface of the pin support portion 13c. This spaced portion is a portion where the cylindrical first pinion gear 12b is arranged, and the minimum gap C is a gap that allows the selection and arrangement of first pinion gears 12b with different diameters. Here, the minimum gap C is, for example, the gap between the inner peripheral surface of the drum portion 13a and the outer peripheral surface of the pin support portion 13c measured on a radial line common to the sun gear 11 and the pinion pin 12a. 1 and 2(a) show an example in which the first pinion gear 12b with the largest diameter D1 among the selectable first pinion gears 12b is used, and therefore in this example, there is a large gap between the inner peripheral surface of the first pinion gear 12b and the outer peripheral surface of the pin support portion 13c. In other words, the minimum interval C is not set to a distance that corresponds only to first pinion gears 12b with one type of outer diameter, but is set to a distance with a margin so that first pinion gears 12b with different outer diameters can be arranged.

[0033] FIG. 2(b) shows an example in which a first pinion gear 12b with a diameter D2 smaller than that of the first pinion gear 12b shown in FIG. 2(a) is used, and FIG. 2(c) shows an example in which a first pinion gear 12b with a diameter D3 smaller than that of the first pinion gear 12b shown in FIG. 2(b) is used. In the example shown in FIG. 2(a), the diameter (tooth tip diameter or pitch circle diameter, hereinafter simply referred to as diameter) D1 of the first pinion gear 12b is large, so that the reduction ratio is so-called large. A large space (or interval) is provided between the inner peripheral surface of the first pinion gear 12b and the outer peripheral surface of the pin support portion 13c. The space or interval is large enough to accommodate another first pinion gear 12b selected from the first pinion gears 12b with a smaller diameter D2 that are prepared in advance.

[0034] An example in which a first pinion gear 12b of a so-called medium diameter D2 selected in this manner is attached is shown in the example in FIG. 2(b). In this case, in order to standardize the ring gear 14, the housing 3, and the second pinion gear 12c, etc., it is necessary to maintain a constant axial distance L (the distance between the central axes) between the input shaft 8 and the pinion pin 12a. To achieve this, compared to the example shown in FIG. 2(a), the sun gear 11 is increased in accordance with the reduction in the diameter of the first pinion gear 12b. In other words, compared to the example shown in FIG. 2(a), the diameters and modules of the first pinion gear 12b and the sun gear 11 are changed.

[0035] In the example shown in Fig. 2(b), the diameter D2 of the first pinion gear 12b employed is so-called medium and is smaller than that of the example shown in Fig. 2(a), so the reduction ratio is so-called medium, smaller than that of the configuration shown in Fig. 2(a). Also, because the diameter D2 of the first pinion gear 12b is so-called medium, there is a relatively large space (or interval) between the outer circumferential surface of the first pinion gear 12b and the above-mentioned drum portion 13a, and between the inner circumferential surface (the surface on the inner circumferential side of the tooth bottom) of the first pinion gear 12b and the outer circumferential surface of the pin support portion 13c, which is large enough to accommodate another first pinion gear 12b with a different diameter.

[0036] FIG. 2(c) shows an example in which that space is used to assemble a first pinion gear 12b with an even smaller diameter D3. Even in this case, the axial distance L between the input shaft 8 and the pinion pin 12a is kept constant in order to standardize the ring gear 14, the housing 3, and the second pinion gear 12c. That is, compared to the example shown in FIG. 2(b), the sun gear 11 is further enlarged in accordance with the reduction in the diameter of the first pinion gear 12b. That is, compared to the example shown in FIG. 2(b), the diameters and modules of the first pinion gear 12b and the sun gear 11 are changed.

[0037] In the example shown in Fig. 2(c), the diameter D3 of the first pinion gear 12b employed is so-called small, and is smaller than that of the example shown in Fig. 2(b), so the reduction ratio is smaller than that of the configuration shown in Fig. 2(b), so that it is so-called small. Also, because the diameter D3 of the first pinion gear 12b is so-called small, a large space (or interval) is provided between the outer circumferential surface of the first pinion gear 12b and the above-mentioned drum portion 13a, while, conversely, there is a small interval between the inner circumferential surface of the first pinion gear 12b (the surface on the inner circumferential side of the tooth bottom) and the outer circumferential surface of the pin support portion 13c, so that they do not come into contact with each other.

[0038] In the embodiment of the present invention, as described above, even if the configuration has a different reduction ratio, at least the ring gear 14 and the second pinion gear 12c meshing therewith are made common. In contrast, the first pinion gear 12b and the sun gear 11 meshing therewith are changed in order to change the reduction ratio. In the embodiment of the present invention, in order to facilitate the assembly of the planetary pinion unit 12 even if the first pinion gear 12b is changed, the ratio (=Zb / Zc) of the number of teeth Zb of the first pinion gear 12b to the number of teeth Zc of the second pinion gear 12c is configured to be an integer. FIG. 3 is a view of the first pinion gear 12b and the second pinion gear 12c viewed from the direction along their central axes, showing the relative phases of these pinion gears 12b and 12c. In the example shown here, the number of teeth of the first pinion gear 12b is "40", and the number of teeth of the second pinion gear 12c is "10", and the ratio between them is "4". Any tooth (in other words, a crest) of the second pinion gear 12c coincides with any tooth (in other words, a crest) of the first pinion gear 12b in the rotation direction. This relationship is the same for any tooth of the second pinion gear 12c, and therefore, when assembling the planetary pinion unit 12, if any tooth of one of the pinion gears 12b, 12c is set to a predetermined phase (rotation position), any tooth of the other pinion gear 12c, 12b can be set to the same phase (rotation position). Therefore, there are fewer restrictions on the phase when assembling the planetary pinion unit 12, and the assembling work is easier.

[0039] In this embodiment of the invention, as described above, by using a sun gear 11 corresponding to the first pinion gear 12b, the axial distance L between the sun gear 11 or the input shaft 8 and the pinion pin 12a becomes constant, and the use of parts can be standardized. In other words, a plurality of types of sun gears 11 having different tooth tip diameters are selected and used.

[0040] 1 and 2 show a structure that assumes that sun gear 11, which is integrated with input shaft 8, is inserted and assembled from the motor 15 side (the right side in Figs. 1 and 2). Therefore, in this structure, in order to enable sun gear 11, which has the largest diameter Ds, to pass through the inside of shaft support boss portion 3a, the minimum inner diameter D7 of the fitting hole into which input bearing 7 is fitted (the outer diameter of input bearing 7, which has the smallest outer diameter) is set to be larger than tooth tip diameter Ds of the largest diameter sun gear 11 expected to be used.

[0041] In the embodiment of the present invention, many parts can be made common. If the common parts are assembled in advance, and then parts that change according to the reduction ratio are assembled to the so-called common parts, the productivity or cost of the in-wheel drive device can be reduced. As an example, the example shown in FIG. 4 is an example configured to assemble the input shaft 8 and the sun gear 11 from the opposite side to the motor 15, opposite to the example shown in FIG. 1 described above. To be more specific, in FIG. 4, the inner diameter of the shaft support boss portion 3a and the inner diameter of the portion through which the input shaft 8 is inserted, such as the caliper 18b of the brake 18, are larger than the outer diameter of the input shaft 8, but unlike the example shown in FIG. 1, they are not restricted by the outer diameter of the sun gear 11, and therefore have diameters according to the strength, input bearing 7, etc. The sun gear 11 is integrated with one end of the input shaft 8 (the end on the left side in FIG. 4) before being assembled into the housing 3. This sun gear 11 may be fitted onto the input shaft 8 and integrated therewith, or may be formed integrally with the input shaft 8 by cutting the material of the input shaft 8 .

[0042] The input bearing 7 is fitted to the outer periphery of the input shaft 8, and a so-called sub-assembly consisting of the input shaft 8 and the input bearing 7 is inserted into the shaft support boss portion 3a from the left side of FIG. 4. In this way, the end of the input shaft 8 (the end on the right side of FIG. 4) is inserted through the brake disc 18a, and the tip of the input shaft 8 is fitted into the joint 17. In this case, the planetary pinion unit 12 may be pre-assembled inside the wheel 2 together with the carrier 13, or the first pinion gear 12b may be meshed with the sun gear 11 after the input shaft 8 and the sun gear 11 are assembled. If the sun gear 11 is separate from the input shaft 8 and is attached to the input shaft 8 before the input shaft 8 is assembled to the housing 3, the sun gear 11 can be machined separately, which increases the degree of freedom when cutting the gears, and thus makes it easier to further reduce the diameter of the sun gear 11.

[0043] After the necessary parts are thus assembled inside the wheel 2, the opening on the left side of the wheel 2 in FIG. 4 is sealed with the cover 20. In this case, a sealant 22 is interposed to provide a liquid-tight seal. The end of the pinion pin 12a abuts against the inner surface of the cover 20 to receive the thrust load of the planetary pinion unit 12, as in the embodiment shown in FIG. 1. The input bearing 7 can be fixed in the axial direction by clamping it in the axial direction between a step portion provided on the inner circumferential surface of the shaft support boss 3a and a flange portion provided on the input shaft 8, as shown in FIG. 4.

[0044] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and can be appropriately modified as necessary. For example, in the above-mentioned embodiment, the motor 15 and the input shaft 8 are arranged on the same axis and connected to each other by the joint 17, but the motor 15 may be attached to any part of the housing 3, and therefore the motor 15 and the input shaft 8 may be connected to each other via some kind of transmission mechanism. [Explanation of symbols]

[0045] 1 Tire 2 Wheels 3. Housing 3a Boss for supporting shaft 3b Flange part 4 Output bearing 5 C-Ring 6 Seal ring 7 Input bearing 8 Input shaft 9 C-Ring 10 Stepped pinion type planetary gear mechanism 11 Sun gear 12 Planetary pinion unit 12a Pinion pin 12b Pinion gear 12c pinion gear 13 Carrier 13a Drum section 13b Holding piece 13c Pin support 14 Ring gear 15 Motor 15a Rotation axis 16 Volts 17 Joint 18 Brake 18a Brake disc 18b Caliper 19 Volts 20 Cover 21 Volts 22 Sealing material C Minimum Spacing D1, D2, D3 (1st pinion gear) diameter Ds (Sun gear) Tooth tip diameter D7 (minimum inner diameter of the fitting hole for the input bearing) L Center distance

Claims

1. An in-wheel type drive device comprising: a stepped pinion type planetary gear mechanism disposed on the inner circumferential side of a wheel on which a tire is mounted; the planetary gear mechanism including: a sun gear driven by a motor; a first pinion gear meshed with the sun gear; a second pinion gear having a smaller diameter than the first pinion gear and integrated with the first pinion gear on the same axis; a carrier which rotates while rotatably holding a pinion pin on which the first pinion gear and the second pinion gear are mounted and which is connected to the wheel; and a ring gear which meshes with the second pinion gear, is disposed concentrically with the sun gear, and is fixed to a housing to which the motor is mounted; The first pinion gear is formed into a cylindrical shape, the carrier has a cylindrical drum portion that covers the first pinion gear and a pin support portion that rotatably supports the pinion pin on an inner peripheral side of the first pinion gear, The minimum distance between the inner peripheral surface of the drum portion and the outer peripheral surface of the pin support portion is set to a distance that allows a plurality of first pinion gears having different tooth tip diameters to be selectively provided on the pinion pin. An in-wheel type drive device characterized by:

2. The in-wheel type drive device according to claim 1, the housing has a shaft support boss portion inserted from one end side in an axial direction of the wheel on an inner peripheral side of the wheel, an input shaft disposed along a central axis of the wheel is rotatably supported via a bearing on an inner peripheral side of the shaft support boss portion; The sun gear is provided on the other end side of the input shaft in the axial direction of the wheel, The minimum inner diameter of the shaft support boss portion into which the bearing is fitted is equal to or larger than the tooth tip diameter of the sun gear that meshes with the first pinion gear having the smallest tooth tip diameter. An in-wheel type drive device characterized by:

3. The in-wheel type drive device according to claim 1 or 2, the carrier has a retaining piece extending radially inward from the drum portion between the first pinion gear and the second pinion gear in the axial direction of the pinion pin, The pin support portion is integrated with the holding piece. An in-wheel type drive device characterized by:

4. The in-wheel type drive device according to claim 1 or 2, An in-wheel type drive device, wherein a ratio of the number of teeth of the first pinion gear to the number of teeth of the second pinion gear is an integer.

5. The in-wheel type drive device according to claim 1, an input shaft that is disposed parallel to the pinion pin at a position a predetermined axial distance from the pinion pin and is driven by the motor; The sun gear that meshes with the selected first pinion gear is a separate member from the input shaft and is attached to the input shaft. An in-wheel type drive device characterized by:

6. The in-wheel type drive device according to claim 5, the sun gear and the first pinion gear are disposed on the other end side opposite to the one end side on which the motor is disposed in the axial direction of the wheel, The opening on the other end side of the wheel is closed by a cover that is detachable from the wheel. An in-wheel type drive device characterized by:

7. The in-wheel type drive device according to claim 2 or 6, A brake for braking the rotation of the input shaft is provided on the end side of the input shaft opposite to the end where the sun gear is provided in the axial direction of the input shaft. An in-wheel type drive device characterized by:

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