COMPACT DRIVE UNIT FOR TRACTION VEHICLES

Abstract

A compact drive unit is predominantly intended for traction vehicles, especially for rail vehicles. This invention allows significant reduction of volume and weight of drive units. The drive unit comprises high-speed electrical motor (1) with passive cooling, which is supplied by power electronics converter (2), whose rotor is supported by bearings (3) along with pinion gear (4) of the input spur/helical gear (5). The output shaft (6) of the gear (5) is a part of the next following gear (7). Output shaft of this gear (7) can be connected either directly or by using the coupling (12) to the axle (8) of the traction vehicle, or to the wheel (9). Alternatively, in case the higher transmission ratio is required, it can be connected to another gears (10), where the output shaft of the gears (10) is connected to the wheel (9), or to the axle (8) of the traction vehicle directly or by using the coupling (12). The drive unit can be equipped with brake (13).

Claims

1. A compact drive unit for traction vehicles consisting of an electrical motor supplied by a power electronics converter, a gearbox and a mechanical coupling to a wheelset or a wheel, wherein the electrical motor is a high-speed electrical motor with a speed over 9000 rpm, its rotor is supported by bearings along with pinion gear of an input spur/helical gear of a high-speed gearbox stage and all together create a rotor assembly, wherein an output shaft of the gear is a part of a following bevel gear, an output shaft of the bevel gear is connected either directly or by using the coupling to an axle of the traction vehicle, or to the wheel, wherein at least the electrical motor and the high-speed gearbox stage are embedded in a single compact housing and the electrical motor is a thermal source for preheating of a lubricant of the high-speed gearbox stage before running the gearbox under extremely low ambient temperatures.

2. A compact drive unit for traction vehicles consisting of an electrical motor supplied by a power electronics converter, a gearbox and a mechanical coupling to a wheelset or a wheel, wherein the electrical motor is a high-speed electrical motor with speed over 9000 rpm, its rotor is supported by bearings along with pinion gear of an input spur/helical gear of a high-speed gearbox stage and all together create a rotor assembly, wherein an output shaft of the gear is a part of a following bevel gear, an output shaft of the bevel gear is connected to additional gears either directly or by using the coupling connected to an axle of the traction vehicle, or to the wheel, wherein at least the electrical motor and the high-speed gearbox stage are embedded in a single compact housing and the electrical motor is a thermal source for preheating of a lubricant of the high-speed gearbox stage before running the gearbox under extremely low ambient temperatures.

3. The compact drive unit for traction vehicles according to claim 1 wherein the electrical motor is with passive cooling.

4. The compact drive unit for traction vehicles according to claim 1 wherein the rotor assembly is supported by at least three bearings.

5. The compact drive unit for traction vehicles according to claim 1 wherein the shaft is connected to a brake.

6. The compact drive unit for traction vehicles according to claim 1 wherein the rotor assembly is connected to a brake.

7. The compact drive unit for traction vehicles according to claim 1 wherein the output of the low-speed gearbox stage is connected to a brake.

8. (canceled)

9. (canceled)

10. The compact drive unit for traction vehicles according to claim 1 wherein the additional gear is designed as a bevel gear, a spur/helical gear, or an epicyclic gear set.

11. The compact drive unit for traction vehicles according to claim 2 wherein the electrical motor is with passive cooling.

12. The compact drive unit for traction vehicles according to claim 2 wherein the rotor assembly is supported by at least three bearings.

13. The compact drive unit for traction vehicles according to claim 2 wherein the shaft is connected to a brake.

14. The compact drive unit for traction vehicles according to claim 2 wherein the rotor assembly is connected to a brake.

15. The compact drive unit for traction vehicles according to claim 2 wherein the output of the low-speed gearbox stage is connected to a brake.

16. The compact drive unit for traction vehicles according to claim 2 wherein the additional gear is designed as a bevel gear, a spur/helical gear, or an epicyclic gear set.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0020] The invention is further explained by means of the drawings.

[0021] FIG. 1 describes basic configuration and cooperation of particular components of invented compact traction drive unit.

[0022] FIG. 2 describes the functionality of optional additional gearbox stages and alternative position of the brake.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] FIG. 1 describes invented compact traction drive unit. The device is composed of a high-speed electrical motor 1 with passive cooling. The motor 1 has typically rated rotor speed over 9 000 rpm. The high-speed electrical motor 1 can be designed as an induction motor, a synchronous motor, a reluctance motor, an electronically commutated (brush-less dc) motor or a direct-current motor. Considering requirements for extremely small volume, high efficiency and reliability, the permanent magnet motor is going to be the most suitable solution.

[0024] The electrical motor 1 is supplied by a power electronics converter 2. Typically, it is a voltage-source inverter. The power electronics converter 2 can also be a current-source inverter.

[0025] From the FIG. 1 it is apparent that a gearbox connected at the drive-end of the motor shaft is divided into two stages: high-speed 11, and low-speed. The rotor of the electrical motor 1 is supported by three rolling-element bearings 3 along with pinion gear 4 of the input spur/helical gear 5 and all together create rotor assembly 14. The location of the middle rolling-element bearing 3 at the motor shaft improves the dynamic stability of the rotor. It also simplifies drive unit assembly. The shaft 6 of the gear is a part of the next following gear 7 and simultaneously it can be connected to the brake 13. The coupling of the brake 13 to the shaft 6 of the high-speed gearbox stage 11 allows important reduction of the dimensions of the brake 13. Alternatively (as shown in FIG. 2), the brake 13 can be connected to the rotor assembly 14 which will further reduce the brake dimensions.

[0026] Output shaft of the gear 7 can be connected either directly or by using the coupling 12 to the axle 8 of the traction vehicle, or to the wheel 9. In case the higher transmission ratio is required, the output shaft of the gear 7 can be connected to another gears 10 (as shown in FIG. 2), where the output shaft of these gears 10 is connected to the wheel 9, or to the axle 8 of the traction vehicle directly or by using the coupling 12. The gear mechanism 7 can be implemented by bevel gear, spur/helical gear, or epicyclic gear set (e.g. planetary gear set). The brake 13 can also be connected to the output of the low-speed gearbox stage. However, this position leads to the larger dimensions and weight of the invented compact traction drive unit.

[0027] Due to significant reduction of both dimensions and weight of particular components of invented drive unit, all the drive unit components can be embedded into one compact housing. This solution significantly decreases the assembly cost and time. However, it is important that at least electrical motor 1 and high-speed gearbox stage 11 are embedded into common compact housing. The integration of the drive unit components into the single housing together with unique construction design of the high-speed motor 1 result in better heat dissipation from all components and it allows a passive cooling of the electrical motor 1 and the whole drive unit. This is very important advantage of the presented invention in comparison to existing traction drive technologies.

[0028] The proposed two-stage solution of the gearbox requires preheating of the lubricant of the high-speed gearbox stage 11 under extremely low ambient temperatures (typically down to 40 C.) before running the gearbox. Due to integration of the drive unit components into one housing, the proposed invention uses preheating of the lubricant of the gearbox 11 by means of the losses of the electrical motor 1. Thus, the power electronics converter 2 feeds the current into the stator winding of the motor 1 which causes production of the heat due to existing losses in the motor 1 (the resistive losses play the major role in this phenomenon). The produced losses, respectively resulting heat is distributed inside the drive unit using the conduction via both drive components and the housing and it preheats in this way the lubricant of the gearbox 11 before its running. Thus, the invented concept does not require any additional device (external thermal source, etc.) and it is very robust and reliable.

[0029] This invention allows significant reduction of drive units volume and weight while demanded traction power/tractive effort is kept. If the electrical motor 1 has the rated speed around 9 000 rpm and the rated power close to 100 kW (typical application for light traction vehicles), our conservative calculation shows that the drive unit volume and weight will decrease at least by 25% while keeping the same traction vehicle characteristics. This invention allows manufacturing of the traction drive unit in a single compact housing. It results in better heat dissipation from the drive components, it is not necessary to use a fan for the drive cooling (passive cooling of the whole drive forms the important advantage in comparison to competitive solutions) and the single drive housing also cuts the assembly cost and time.