A GEAR BOX

Technical Field

The present invention relates to a gearbox which is used in electric vehicles and enables to receive the forces, that occur in an axial direction, through the bearing by means of the shaft, gear and bearing orientation created in the transmission systems that receive power from the motor and transmit it to the wheels and to prevent the mounting of gears in a different way.

Background of the Invention

Gearboxes are used for changing the speed and torque in mechanical systems and contain parts such as gears, bearings and shafts for this. Single-speed two-stage gearboxes used in electric vehicles are one of the gearboxes which transmit the power they receive from the motor to the wheels. The said gearboxes contain three shafts and four gears on them. Four gears create the two-stage gearbox. In singlespeed two-stage gearboxes, when the driving gear is defined as the pinion gear and the driven gear is defined as the wheel gear, the wheel gear of the first stage and the pinion gear of the second stage are connected to the second shaft -that is located in the middle inside the gear box- together. The said gears apply axial force to each other, the direction of the total axial force varies by the driving modes such as normal driving mode and regenerative braking mode. If the gears apply axial load to each other such that they separate from each other in the gearbox, it is required to apply an axial counter force to prevent the said load from not separating the gears. At the same time, different driving modes cause the shaft to be loaded sometimes by driving the 2 ^nd stage pinion, and sometimes by driving the 1 ^st stage wheel as well. This causes the contact surfaces of the gears be created on both sides of the tooth flanks and flanks -different from each other- are loaded with different loads. In the state of the art, there are solutions such as shrink fit, spline shrink fit and using locknut in order to create a force in the opposite direction of the axial force and nevertheless, mostly a solution wherein the bearing located at both ends of the shaft fits onto the two-stage pinion and again uses the axial bearing surfaces on the two-stage pinion is chosen.

Assembly methods are used to attach the gears to each other in a certain direction. The solutions used today use the tight fittings and lock nut parts mentioned above to transmit the axial forces that may occur in both directions to the bearings and from there to the casings that hold the bearings. On the other hand, the solution of connecting the gears to each other using assembly methods prolongs the assembly time and brings about incorrect assembly. Therefore, solutions to overcome these problems are needed today. Mounting methods are used in order to attach the gears to each other in a certain direction. Solutions, which are already used today, use the above-mentioned shrink fittings and lock nut parts so as to transmit the axial forces that may occur in both directions to the bearings and to the casings, maintaining the bearings, therefrom. On the other hand, the solution of connecting the gears to each other using assembly methods prolongs the assembly time and brings about incorrect assembly. Therefore, solutions to overcome these problems are needed today, the solution of connecting the gears to each other by using mounting methods prolongs the mounting time and brings about incorrect mounting. Therefore, today there is need for solutions to overcome the said problems.

The Chinese patent document no. CN104565310A, an application included in the state of the art, discloses a gear assembly for vehicle gearboxes. The said gear assembly comprises a drive shaft provided with an annular step. A plurality of bearings are mounted in the gear wheel disk included in the gear assembly. The front ends of the bearings are provided with a fixing ring at the front end opening of the gear wheel disk. With the gear assembly configuration disclosed in the said Chinese patent document, abraded and damaged gear wheel disk can be replaced easily. The Chinese patent document no. CN104565310A does not mention that the gear wheel disk has a stepped structure like a shaft. The Russian patent document no. RU2762981C1, an application in the state of the art, discloses a gearbox. The said gearbox is used to as a two-stage gearbox. The output shaft included in the gearbox has a stepped structure. The said output shaft comprises an inner ring which interacts with the protrusions located on the outer ring during its rotation and comprises toothed protrusions on its outer surface. On the other hand, the base part comprises a working part which interacts with the eccentric shaft by means of the bearing. In the inventive gearbox, the input and output shafts are located on the same axis of rotation and the eccentric shaft has an offset structure.

Summary of the Invention

An objective of the present invention is to realize a gearbox wherein the bearings fit into the shaft and it is ensured that an axial load is created upon one of the bearings contacts the gear and uses the gear surface as a bearing surface.

Another objective of the present invention is to realize a mounting apparatus whereby it is ensured that gears are prevented from being mounted to the shaft in a different way, by means of a formal change such as a tab or stepped structure created on the shaft diameter.

Detailed Description of the Invention

“A Gearbox” realized to fulfil the objectives of the present invention is shown in the figure attached, in which:

Figure l is a section view of the inventive gearbox.

The components illustrated in the figure are individually numbered, where the numbers refer to the following: 1. Gearbox

2. Shaft

3. Gear

4. Bearing

O: Seat surface

B : Stepped structure

The inventive gearbox (1) which enables to receive the forces, that occur in an axial direction, through the bearing by means of the shaft, gear and bearing orientation created in the transmission systems that receive power from the motor and transmit it to the wheels and to prevent the mounting of gears in a different way comprises:

- at least one shaft (2) which performs the function of driving or the function of being driven according to the driving mode;

- at least one gear (3) which is located on the shaft (2) and performs the exact opposite of the function performed by the shaft (2);

- two rollers (4) which are located at each end of the shaft (2), one for each, and whereby it is ensured that the torque is transmitted up to a certain level by creating a counter axial load upon the first one creates a seat surface (O) by contacting the gear (3) and wherein the second one is located on the other end of the shaft (2).

The inventive gearbox (1) comprises three shafts (2) one of which is located in the middle of the casing and the other is a two-stage pinion gear shaft and four gears (3) located on the shafts (2) one of which is a first-stage wheel gear shaft (3). With the said four gears (3) located in the gearbox (1), a two-stage gearbox used in electric vehicles is obtained. The said gearbox (1) receives power from the motor and it is used in transmission systems that transmits power to the wheels.

In the inventive gearbox (1), the gear (3) is located on the shaft (2) -that is present in a middle position- together with two rollers (4). One bearing (4) is located in one end of the shaft (2) and a gear (3) contacting the bearing (4) from one of its surfaces is located on the other end thereof together with one bearing (4). In the inventive gearbox (1), a stepped structure (B) comprising a plurality of steps is located on the junction surfaces of the shaft (2) and the gear (3) where the roller (4) is not located. The stepped structure (B) functions as a pokoyoke by creating a tab on the shaft (2). Mounting of the gears to the shaft (2) is prevented in a different way by means of the said stepped structure (B).

In one preferred embodiment of the invention, the rollers (4) are located on different ends on a shaft (2). One of the rollers (4) fits onto the shaft on one end of the shaft

(2) and abuts against the gear (3) from one surface thereof. Thereby, a seat surface (O) is created between the gear (3) and the roller (4). And the other bearing (4) is located in the other end of the shaft (2) and fits onto the shaft (2). The bearings (4) compress the gear (3) and the shaft (2) and the forces with separation direction to occur in the gearbox (1) according to the axial direction in the driving mode are met by the bearings (4). Thus, the need for an axial bearing force that occurs due to using extra pieces or shrink fit and will cause serious changes based on temperature, manufacturing tolerance of pieces is eliminated. At the same time, torque transmission is provided up to a certain level due to the fact that the bearings (4) compress the gear (3) and the shaft (2).

In the mounting of the inventive gearbox (1), the gear (3) is shrink fit to the shaft (2) and by means of the stepped structure (B) located in the side surfaces where the gear

(3) and the shaft (2) contact, it is guaranteed that the gear (3) and the shaft (2) flanks, namely the side surfaces thereof, are positioned correctly and the shrink fit only bears the torque. With the stepped mounting process, a separate measure is not necessary anymore in the mounting of the gear (3) and the shaft (2). Upon the mounting of the gear (3) to the shaft (2), one of the bearings (4) abuts against the gear (3) and then fits into the shaft (2). Thereby, a seat surface (O) is created between the gear (3) and the bearing (4), a compression force is created in a certain direction by means of the seat surface (O) and the said compression force supports the torque transmission. The compression force created at one end of the bearing (4) and the shaft (2) by means of abutting against the gear (3); using an extra piece such as lock nut, segment; or shaft or spline shrink fit eliminate the need for methods of creating an axial force the amount of which will change substantially with a productive and tolerant method. It is possible to develop various embodiments of the inventive gearbox (1); the invention cannot be limited to examples disclosed herein and it is essentially according to claims.