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 traction rail vehicles compact drive unit for mounting on outside of a wheel of a traction rail vehicle, the traction rail vehicles compact drive unit comprising an electrical motor supplied with voltage or current from a power electronics converter, a gearbox divided into a high-speed gearbox stage and a low-speed gearbox stage, and a mechanical coupling to a wheelset or the wheel, wherein the high-speed gearbox stage includes an input spur/helical gearset that defines a set of pinion gear and spur/helical gear, wherein the electrical motor is a high-speed electrical motor with a speed over 9000 rpm, its rotor is supported by bearings along with the pinion gear of the input spur/helical gearset of the high-speed gearbox stage and all together create a rotor assembly having an axis of rotation that is perpendicular to the axis of rotation of the wheel, wherein the low-speed gearbox stage includes a following bevel gearset that defines a set of bevel gears, wherein an output shaft of the spur/helical gearset of the high-speed gearbox stage is a part of the following bevel gearset of the low-speed gearbox stage, an output shaft of the bevel gearset of the low-speed gearbox stage is connectable 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, wherein the power electronics converter is arranged to feed current into a stator winding of the electrical motor which causes production of heat due to existing losses in the electrical motor, wherein the heat is distributed inside the drive unit using conduction via both drive components and the housing for preheating of a lubricant of the high-speed gearbox stage before motor rotation and running the gearbox under extremely low ambient temperatures.

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

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

4. The traction rails vehicles compact drive unit according to claim 1 wherein the output shaft of the high-speed gearbox stage is connected to a brake.

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

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

7. The traction rail vehicles compact drive unit according to claim 1, wherein the output shaft of the bevel gearset of the low-speed gearbox stage is connected to the wheelset or the wheel of the traction vehicle via additional gears.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The invention is further explained by means of the drawings.

(2) FIG. 1 describes basic configuration and cooperation of particular components of invented compact traction drive unit.

(3) FIG. 2 describes the functionality of optional additional gearbox stages and alternative position of the brake.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) 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.

(5) 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.

(6) 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 gearbox stage 11, and low-speed gearbox stage. The high-speed gearbox stage 11 includes an input spur/helical gearset that defines a set of pinion gear 4 and spur/helical gear 5. The low-speed gearbox stage includes a following bevel gearset that defines a set of bevel gears 7. 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 high-speed gearbox stage 11 is a part of the following bevel 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.

(7) Output shaft of the bevel 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 bevel gear 7 can be connected to additional gears 10 (as shown in FIG. 2), where the output shaft of these additional 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 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.

(8) 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.

(9) 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.

(10) 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.