Gear mechanism

Abstract

In conventional gear mechanisms, there was a demand for reducing the length in the longitudinal direction of the vehicle, especially in vehicles like automobiles where the space for mounting equipment is extremely limited. [Solution] The gear mechanism includes a drive gear 4 fixed to the output shaft 3 of the motor 2 within a housing 1, a driven gear 5 whose rotation axis is parallel to the drive gear 4, a rotating gear 6 fixed on the axis of the driven gear 5, and a revolving gear 7 whose rotation axis is perpendicular to the rotating gear 6. The driven gear 5 has a concentric annular recess 5A, and a first bearing B1 that rotatably holds the driven gear 5 is housed in the recess 5A. The end of the shaft portion 6A of the rotating gear 6 has a second bearing B2 that rotatably holds the coaxial portion 6A. This gear mechanism achieves a reduction in dimensions not only in the direction perpendicular to the axis of the motor 2, but also in the direction along the axis of the motor 2, providing a gear mechanism with excellent applicability to automobile drive systems.

Description

Technical Field

[0001] The present invention relates to a gear mechanism, and more particularly to a gear mechanism suitable for a drive device of an automobile.

Background Art

[0002] As a conventional gear mechanism, for example, there is one described in Patent Document 1. Patent Document 1 describes a gear mechanism that transmits the rotation of a motor to a differential device and an axle in a vehicle. This gear mechanism arranges the motor in a posture where the rotation axis faces in the longitudinal direction of the vehicle, and includes a pinion that is rotationally driven by the motor and a hypoid gear whose rotation axis is arranged orthogonally to that of this pinion, thereby achieving a reduction in the dimension in the vehicle width direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, while the above-described conventional gear mechanism realizes a reduction in the dimension in the vehicle width direction, the dimension in the longitudinal direction of the vehicle becomes longer, and in a vehicle such as an automobile where the mounting space for equipment is extremely narrow and limited, a reduction in the dimension in the longitudinal direction of the vehicle has been desired.

[0005] The present invention has been made in view of the above conventional situation, and an object thereof is to provide a gear mechanism that can realize a reduction in dimensions not only in the direction orthogonal to the axis of the motor but also in the direction along the axis of the motor, and has excellent applicability to a drive device of an automobile.

Means for Solving the Problems

[0006] The gear mechanism according to the present invention comprises a drive gear fixed to the output shaft of a motor, a driven gear whose rotation axis is arranged parallel to the drive gear, a rotating gear fixed on the axis of the driven gear, and a revolving gear whose rotation axis is arranged perpendicular to the rotating gear, all housed in a housing, and transmits the rotation of the drive gear to the revolving gear via the driven gear and the rotating gear. This gear mechanism is characterized in that the driven gear has an annular recess concentrically on the opposite side of the revolving gear, and a first bearing is housed in the recess to rotatably hold the driven gear relative to the housing, and the rotating gear has a shaft portion that penetrates the center of the driven gear, and a second bearing is arranged at the end of the shaft portion protruding from the driven gear to rotatably hold the shaft portion relative to the housing. [Effects of the Invention]

[0007] By adopting the above configuration, the gear mechanism according to the present invention can reduce the dimensions not only in the direction perpendicular to the motor axis but also in the direction along the motor axis. In vehicles such as automobiles, where the mounting space for equipment is very narrow and limited, it is possible to reduce the dimensions in both the vehicle width direction and the vehicle longitudinal direction, resulting in excellent applicability to vehicle drive systems. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view illustrating the main part of the gear mechanism according to the present invention. [Figure 2] This is a perspective view illustrating the overall configuration of a gear mechanism. [Figure 3] This is a side view illustrating a comparison between the gear mechanism according to the present invention (right side) and a gear mechanism with a general configuration (left side). [Modes for carrying out the invention]

[0009] The gear mechanism shown in Figures 1 and 2 comprises a drive gear 4 fixed to the output shaft 3 of the motor 2, a driven gear 5 whose rotation axis is parallel to the drive gear 4, a rotating gear 6 fixed on the axis of the driven gear 5, and a revolving gear 7 whose rotation axis is perpendicular to the rotating gear 6, all housed in a housing 1 partially shown in Figure 1. This gear mechanism transmits the rotation of the drive gear 4 to the revolving gear 7 via the driven gear 5 and the rotating gear 6. Note that Figure 2 shows the overall configuration of the gear mechanism, and details such as the holding portion of the rotating gear 6 differ from the configuration of the embodiment shown in Figure 1.

[0010] The gear mechanism described above constitutes the vehicle's drive system, with the output shaft 3 of the motor 2 oriented in the vehicle's longitudinal direction (left-right direction in Figure 1), and the rotation axes of the rotation gear 6 and the revolution gear 7 being perpendicular in the horizontal plane when mounted on the vehicle. The rotation of the motor 2 is transmitted to the differential device and axle connected to the revolution gear 7.

[0011] The drive gear 4 and driven gear 5 of the gear mechanism described above are, for example, helical gears. The orbital gear 7 is, for example, a hypoid gear with an annular tooth arrangement, and the rotational gear 6 is a pinion gear that engages with the orbital gear 7 and has a shaft portion 6A that penetrates the center of the driven gear 5. The housing 1 houses the gear mechanism together with the motor 2, and a predetermined amount of lubricating oil is stored inside it.

[0012] In the gear mechanism described above, the driven gear 5 has a concentric annular recess 5A on the opposite side of the revolving gear 7 (right side in Figure 1), and a first bearing B1 is housed in the recess 5A, which rotatably holds the driven gear 5 relative to the housing 1. A second bearing B2 is positioned at the end of the shaft portion 6A that protrudes from the driven gear 5 on the opposite side of the revolving gear 7, which rotatably holds the shaft portion 6A relative to the housing 1. The first bearing B1 shown is a ball bearing. The second bearing B2 can be a ball bearing, a needle bearing, or the like.

[0013] Furthermore, the gear mechanism described above has a configuration in which the diameter (radius R2) of the second bearing B2 is smaller than the diameter (radius R1) of the first bearing B1. This diameter is what is known as the bearing diameter, but in the case of a ball bearing, for example, it may be the outer diameter of the outer race, or it may be the diameter of the circle connecting the centers of each ball.

[0014] Furthermore, as shown by the dashed line in Figure 1, the gear mechanism described above has a configuration in which the motor bearing Bm, which holds the drive gear 4 side of the output shaft 3 in the motor 2, and the second bearing B2 overlap at least partially in a direction perpendicular to the rotation axis of the rotating gear 6 (vertical direction in Figure 1). In the illustrated example, the motor bearing Bm and the second bearing B2 are arranged to overlap almost on the same plane in the vertical direction in Figure 1.

[0015] Furthermore, as previously mentioned, the gear mechanism described above consists of a rotating gear 6 and a revolving gear 7, which are a pinion gear and a hypoid gear whose axes of rotation are perpendicular to each other in the horizontal plane, and as shown on the right side of Figure 4, the diameter of the first bearing B1 is larger than the inner diameter of the teeth of the revolving gear 7.

[0016] Here, the left side of Figure 3 shows a general configuration of a pinion gear 56 and a hypoid gear 57 with their rotation axes arranged orthogonally. In this general configuration, the rotation axis Cp of the pinion gear 56 is offset downward with respect to the horizontal line H passing through the center of the hypoid gear 57, and the lower part of the bearing 58 of the pinion gear 56 is immersed in lubricating oil stored in the housing (oil level indicated by OL).

[0017] In contrast, the above gear mechanism aligns the rotation axis of the rotation gear 6 with the horizontal line H passing through the center of the orbital gear 7, meaning the pinion gear is not offset, and the diameter of the first bearing B1 is larger than the inner diameter of the teeth of the orbital gear 7. As a result, although the rotation gear (pinion gear) 6 is on the upper side in the above gear mechanism compared to a general configuration, the lower part of the first bearing B1 is more easily immersed in lubricating oil (OL), thus enabling a reduction in the amount of lubricating oil used and a reduction in transmission efficiency.

[0018] In the above-described gear mechanism, the driving gear 4 of the motor 2 and the driven gear 5 are engaged, the driven gear 5 and the rotating gear 6 are integrated, and the rotating gear 5 and the revolving gear 7 are engaged, so that the rotation of the motor 2 is transmitted in the order of the driving gear 4, the driven gear 5, the rotating gear 6, and the revolving gear 7, and two-stage speed change is performed in this rotation transmission. At this time, the above-described gear mechanism scoops up lubricating oil by the revolving gear (hypoid gear) 7 and supplies the lubricating oil to the driving gear 4, the driven gear 5, and the rotating gear 6, thereby maintaining the lubricity of the gear mechanism and cooling each part.

[0019] The gear mechanism having the above configuration performs rotational transmission to the revolving gear 7 in which the rotation axes are orthogonally arranged with respect to the output shaft 3 of the motor 2 and the rotation axis of the rotating gear 6, so that two-stage speed change is performed with good space efficiency.

[0020] Further, in the configuration of the rotating gear 6 and the revolving gear 7 in which the rotation axes are orthogonally arranged with respect to each other, if the shaft portion 6A of the rotating gear 6 has a both-end supported structure, it is difficult to shorten the axial direction. In contrast, in the above-described gear mechanism, a first bearing B1 that rotatably holds the driven gear 5 with respect to the housing 1 is accommodated in a recess 5A formed in the driven gear 5, and at the end of the shaft portion 6A of the rotating gear 6, A second bearing B that rotatably holds the shaft portion 6A with respect to the housing 1 is arranged.

[0021] As a result, the shaft portion 6A of the rotating gear 6 in the above-described gear mechanism exhibits a single-end supported structure by the second bearing B2, but is actually reliably held in a both-end supported structure by the first bearing B1 and the second bearing B2.

[0022] In this way, the above-described gear mechanism can realize shortening of the dimensions not only in the direction orthogonal to the axis of the motor 2 but also in the direction along the axis of the motor 2 by arranging the driven gear 5 integrated with the rotating gear 6 and the first bearing B1 at the same position. In a vehicle such as an automobile where the mounting space of the device is very narrow and limited, shortening of the dimensions in both the vehicle width direction and the vehicle longitudinal direction can be realized, and the applicability to the drive device of the vehicle is excellent.

[0023] Further, in the above-described gear mechanism, the diameter of the second bearing B2 is made smaller than the diameter of the first bearing B1 Therefore, in the direction orthogonal to the rotation axis of the idler gear 6, the distance between the motor 2 and the rotation axis of the idler gear 6 can be shortened, and further miniaturization in the direction orthogonal to the output shaft 3 of the motor 2, i.e., the vehicle width direction in a vehicle, can be achieved.

[0024] Furthermore, in the above-described gear mechanism, in the direction orthogonal to the rotation axis of the idler gear 6, the motor bearing Bm and the second bearing B2 are arranged such that at least a part of them overlaps with each other. Thereby, it is easy for the gear mechanism to divide the housing 1 into a motor portion and a gear portion at the positions of the motor bearing Bm and the second bearing B2, and when manufacturing the housing 1 by casting, the structure of the casting mold can be simplified.

[0025] The gear mechanism according to the present invention is not limited to the above-described embodiment in its configuration, and can be appropriately changed without departing from the gist of the present invention.

Explanation of Reference Numerals

[0026] 1 Housing 2 Motor 3 Output Shaft 4 Driving Gear 5 Driven Gear 5A Concave Portion 6 Idler Gear 6A Shaft Portion 7 Revolving Gear B1 First Bearing B2 Second Bearing Bm Motor Bearing

Claims

1. A gear mechanism comprising, within a housing, a drive gear fixed to the output shaft of a motor, a driven gear whose rotation axis is parallel to the drive gear, a rotating gear fixed on the axis of the driven gear, and a revolving gear whose rotation axis is perpendicular to the rotating gear, wherein the rotation of the drive gear is transmitted to the revolving gear via the driven gear and the rotating gear, The driven gear has a concentric annular recess on the opposite side of the revolving gear, and a first bearing is housed in the recess, which rotatably holds the driven gear relative to the housing. The aforementioned rotating gear has a shaft portion that penetrates the center of the driven gear, A gear mechanism characterized in that a second bearing is positioned at the end of the shaft portion protruding from the driven gear, the bearing rotatably holds the shaft portion relative to the housing.

2. The gear mechanism according to claim 1, characterized in that the diameter of the second bearing is smaller than the diameter of the first bearing.

3. The gear mechanism according to claim 1, characterized in that the motor bearing that holds the drive gear side of the output shaft of the motor and the second bearing are arranged so that at least a portion of them overlap each other in a direction perpendicular to the rotation axis of the rotating gear.

4. The gear mechanism according to claim 1, characterized in that the rotating gear and the revolving gear are a pinion gear and a hypoid gear whose axes of rotation are perpendicular to each other in the horizontal plane, and the diameter of the first bearing is larger than the inner diameter of the teeth of the revolving gear.

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