Planetary gearbox

Abstract

The present invention relates to a planetary gear transmission box, comprising a housing part, a first planetary gear transmission stage and a second planetary gear transmission stage, wherein the first planetary gear transmission stage comprises a first sun gear, a first planet carrier and a first inner gear ring, and the second planetary gear transmission stage comprises a second sun gear, a second planet carrier and a second inner gear ring, wherein the first sun gear is connected to an external input element, the first planet carrier is connected to the second sun gear, the second planet carrier is connected to an output element, the second planet carrier is directly supported on the housing, the transmission ratio of the transmission box is greater than 25, and the second planet carrier is directly supported on the housing. The present invention increases the stall torque of the gear box, reduces the output speed, and thus the bearing member can be eliminated at the output end.

Description

Technical Field

[0001] The invention belongs to the technical field of transmission, and in particular relates to a planetary gear transmission box. Background Art

[0002] As cars continue to develop towards intelligence and comfort, electric tailgates have become a trend, and more and more cars are beginning to use electric tailgates. Electric tailgates are generally driven by a motor to drive the gearbox, which in turn drives the tailgate to open and close.

[0003] Figure 1 It is an existing gearbox structure for electric tailgate. The gearbox has a first-stage planetary gear transmission train PG1 and a second-stage planetary gear transmission train PG2. Each stage of the planetary gear transmission train consists of a sun gear, a ring gear and a planet carrier. The power is input from the sun gear of the first-stage planetary gear transmission train PG1, output to the second-stage planetary gear transmission train PG2 through the planet carrier, and then output from the planet carrier of the second-stage planetary gear transmission train PG2. The planet carrier of the second-stage planetary gear transmission train PG2 is supported on bearing B.

[0004] This type of gearbox is designed with a low transmission ratio, generally less than 25, which results in a low torque transmission, and the output torque is generally less than 5Nm; due to the small torque transmission, the strength requirement for the sun gear is also low, so at least the sun gear of the first-stage planetary gear transmission train can be made of plastic. At the same time, due to the low transmission ratio, when using this type of gearbox, a symmetrical setting is generally adopted.

[0005] Therefore, this gearbox has the disadvantages of low transmission torque and high cost. At the same time, since two gearboxes need to be arranged, the space occupied is also larger. Summary of the invention

[0006] In order to solve the above technical problems to a certain extent, the present invention proposes the following technical solutions.

[0007] A planetary gear transmission box comprises a housing portion, a first planetary gear transmission stage and a second planetary gear transmission stage, wherein the first planetary gear transmission stage comprises a first sun gear, a first planet carrier and a first inner gear ring, and the second planetary gear transmission stage comprises a second sun gear, a second planet carrier and a second inner gear ring, the first sun gear is connected to an external input element, the first planet carrier is connected to the second sun gear, the second planet carrier is connected to an output element, and the transmission ratio of the gear transmission box is greater than 25.

[0008] A planetary gear transmission box includes a housing part, a first planetary gear transmission stage and a second planetary gear transmission stage, wherein the first planetary gear transmission stage includes a first sun gear, a first planet carrier and a first inner ring gear, and the second planetary gear transmission stage includes a second sun gear, a second planet carrier and a second inner ring gear, the first sun gear is connected to an external input element, the first planet carrier is connected to the second sun gear, the second planet carrier is connected to an output element, and the second planet carrier is directly supported on the box body.

[0009] According to the above two technical solutions, the present invention redesigns the transmission ratio of the gearbox to make it greater than or equal to 25, preferably between 25-30, thereby increasing the stall torque of the gearbox. In addition, the increase in the transmission ratio reduces the output speed, so the bearing can be removed at the output end.

[0010] Furthermore, the second sun gear is made of metal.

[0011] Further, the housing portion includes an intermediate housing, the intermediate housing is provided with a support portion extending radially inwardly, and the first planet carrier is supported by the support portion.

[0012] Furthermore, the shell part also includes a first end cover and a second end cover.

[0013] Furthermore, a bearing is arranged in the central through hole of the first end cover.

[0014] Furthermore, a gasket is provided between the first end cover and the planetary gear located on the first planetary carrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other specific features and advantages will become apparent from the following description, which is given as a rough and non-limiting guide in conjunction with the accompanying drawings, in which:

[0016] Figure 1 It is a schematic diagram of the gear box structure in the prior art.

[0017] Figure 2 It is a schematic structural diagram of the gear box of the present invention.

[0018] Figure 3 It is an exploded view of the parts of the gear box of the present invention.

[0019] All the drawings are only schematic and not necessarily drawn to scale, and they only show those parts necessary for explaining the present invention, and other parts are omitted or only mentioned. That is, in addition to the parts shown in the drawings, the present invention may also include other parts. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0021] See also Figure 2 and Figure 3 The housing part of the gearbox of the present invention includes a first end cover 1 located on the left, a second end cover 8 located on the right, and a gearbox intermediate housing 4. The first end cover 1 and the second end cover 8 close the gearbox intermediate housing 4 from both sides, and the transmission components are arranged in the closed space.

[0022] The transmission component is a two-stage transmission device. Specifically, the first transmission stage is composed of the first sun gear 3, the first planet carrier 5, and the first internal gear ring formed on the inner side of the gearbox intermediate housing 4. The power input by the motor is transmitted to the first sun gear 3, and then transmitted to the first planet carrier 5 through the planetary gear, and then transmitted to the second transmission stage.

[0023] The second transmission stage includes a second sun gear, a second inner gear ring 6 and a second planet carrier 7. The second inner gear ring 6 is fixedly arranged on the gearbox intermediate housing 4. Figure 2 It can be seen that the first planet carrier 5 and the second sun gear are configured as an integral part. Of course, this is only an exemplary embodiment, and the first planet carrier 5 and the second sun gear may not be configured as an integral part, but may be made of separate components. The power is finally output by the second planet carrier 7.

[0024] from Figure 2 It can be seen that a bearing 2 is provided in the central through hole of the first end cover 1 for supporting the input shaft. No bearing is provided in the central through hole of the second end cover 8, and the second planet carrier 7 is directly supported in the through hole. Compared with the existing transmission box, the transmission ratio of the transmission box of the present invention is higher (up to 30), so that the output speed of the second planet carrier 7 is lower. Due to the lower speed, the wear between the second end cover 2 is relatively reduced, so that the bearing does not need to be provided, thereby reducing the cost.

[0025] In addition, as a preferred embodiment, lubricating oil is provided between the second planet carrier 7 and the second end cover 8 to further reduce the wear between the two.

[0026] from Figure 2 and Figure 3 It can also be seen in the figure that a gasket 9 is provided between the first end cover 1 and the planetary gears on the first planetary carrier 5 to reduce friction.

[0027] As another preferred embodiment of the present invention, Figure 2 It can be seen that on the intermediate housing 4 of the gearbox of the present invention, a support portion extending radially inward is provided to support the first planet carrier 5. Through this support structure, the operation of the first planet carrier 5 can be more stable, thereby reducing the working noise of the gearbox.

[0028] Further, from Figure 2 It can also be seen that the support portion of the intermediate housing 4 is provided with a protrusion for axially supporting the first planetary carrier 5 at a radial edge close to the first planetary carrier 5, and the second end cover 8 is provided with a protrusion for axially supporting the second planetary carrier 7 at a radial edge close to the second planetary carrier 7.

[0029] Therefore, since the present invention redesigns the transmission ratio of the gearbox to be greater than or equal to 25, preferably between 25-30, the stall torque of the gearbox is increased to be greater than 5.5 Nm; accordingly, due to the increase in torque, in order to increase the strength of the structural parts, the second sun gear is made of metal material. Of course, the first sun gear, the first planet carrier and the second planet carrier can also be made of metal materials. In addition, since the increase in the transmission ratio reduces the output speed, the bearing part can be eliminated at the output end.

[0030] The present invention has been clearly and completely described with reference to the above exemplary embodiments, and it should be understood by those skilled in the art that various other embodiments can be conceived by modifying the disclosed technical solutions without departing from the spirit and scope of the present invention. These embodiments should be understood to fall within the scope of the present invention determined based on the claims and any equivalent technical solutions thereof.

Claims

1. A planetary gear transmission box for an electric tailgate, comprising a housing portion, a first planetary gear transmission stage and a second planetary gear transmission stage, wherein the first planetary gear transmission stage comprises a first sun gear (3), a first planet carrier (5) and a first inner gear ring, and the second planetary gear transmission stage comprises a second sun gear, a second planet carrier (7) and a second inner gear ring (6), wherein the first sun gear (3) is connected to an external input element, the first planet carrier (5) is connected to the second sun gear, and the second planet carrier (7) is connected to an output element, characterized in that: The transmission ratio of the gear transmission box is between 25 and 30. The second planet carrier (7) is directly supported on the housing part. The housing part includes an intermediate housing (4). The intermediate housing (4) is provided with a support portion extending radially inward. The first planet carrier (5) is directly supported by the support portion. The housing part also includes a first end cover (1) and a second end cover (8). A bearing (2) is provided in the central through hole of the first end cover (1). The material of the second sun gear is metal. Lubricating oil is provided between the second planet carrier (7) and the second end cover (8). The support portion of the intermediate housing (4) is provided with a protrusion for axially supporting the first planet carrier (5) at a radial edge close to the first planet carrier (5). The second end cover (8) is provided with a protrusion for axially supporting the second planet carrier (7) at a radial edge close to the second planet carrier (7).

2. The planetary gear transmission box according to claim 1, characterized in that: A gasket (9) is provided between the first end cover (1) and the planetary gear located on the first planetary carrier (5).

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