KR-20260066273-A - Driving device for electric vehicles

KR20260066273AKR 20260066273 AKR20260066273 AKR 20260066273AKR-20260066273-A

Abstract

A drive unit for an electric vehicle is disclosed. A drive unit for an electric vehicle according to one embodiment of the present invention combines two motors and two to four reduction gear units to increase axial mounting capacity even when required performance specifications increase, and operates to appropriately perform its role according to the driving range of the electric vehicle, thereby maintaining cost-effectiveness gains and effects or maintaining high driving efficiency.

Inventors

임성엽

Assignees

현대자동차주식회사
기아 주식회사

Dates

Publication Date: 20260512
Application Date: 20241104

Claims (12)

In a drive system for an electric vehicle, A first motor comprising a first motor shaft formed of a hollow shaft that is positioned on the line of one of the two drive shafts that connect the differential and both wheels to transmit driving force to the two wheels, and which is positioned overlappingly with the one drive shaft without rotational interference; A second motor positioned parallel to the first motor; A first idler shaft positioned parallel to the first motor shaft of the first motor and the second motor shaft of the second motor; A first reduction gear unit comprising a second output gear fixed to the second motor shaft and a first idler gear fixed to one side of the first idler shaft and externally meshing with the second output gear; A second reduction gear mechanism comprising a second idler gear fixed to the other side of the first idler shaft and a differential ring gear of the differential that externally meshes with the second idler gear; and A third reduction gear mechanism that directly or indirectly transmits the rotational power of the first motor to the first idler gear on the first idler shaft through the first output gear; A drive unit for an electric vehicle including
In paragraph 1, The above third reduction gear mechanism A drive device for an electric vehicle formed by the first output gear fixed to the first motor shaft engaging externally with the first idler gear fixed to one side of the first idler shaft.
In paragraph 1, The above third reduction gear mechanism A drive device for an electric vehicle formed by the first output gear, which is rotatably disposed on the first motor shaft and selectively receives rotational power input from the first motor, and the first idler gear engaging externally.
In paragraph 3, The above driving device is A drive device for an electric vehicle comprising a first planetary gear set arranged on the first motor shaft having first, second, and third rotational elements, and further comprising a fourth reduction gear mechanism that reduces and outputs rotational power input from the first motor to the first output gear.
In paragraph 4, The above first planetary gear set is A drive device for an electric vehicle in which the first rotating element is connected to the first motor shaft and operates as an input element, the second rotating element is selectively connected to the first output gear and operates as an output element, and the third rotating element is fixed to the housing and acts as a fixed element.
In paragraph 5, The above first planetary gear set is A drive device for an electric vehicle comprising a single pinion planetary gear set, wherein the first, second, and third rotating elements comprise a first sun gear, a first planetary carrier, and a first ring gear.
In paragraph 5, The above first output gear is A drive device for an electric vehicle that is positioned on the above-mentioned one-sided drive shaft without rotational interference and is selectively connected to the second rotating element of the first planetary gear set through a clutch.
In paragraph 5, The above first output gear is A drive device for an electric vehicle that is positioned without rotational interference on an output shaft connected to a second rotating element of the first planetary gear set and is selectively connected to the output shaft through a clutch.
In paragraph 8, The above output shaft is A drive device for an electric vehicle made of a hollow shaft and overlapped and arranged on one side drive shaft without rotational interference.
In Article 7 or Article 8, The above clutch A drive system for an electric vehicle comprising a dog clutch, a wet clutch, a synchronizer, or a one-way clutch.
In paragraph 1, The above third reduction gear mechanism A drive device for an electric vehicle that forms a second idler shaft on the opposite side of the first reduction gear mechanism based on the first and second motors, and transmits the rotational power of the first motor to the first idler gear through a third idler gear on the second idler shaft, an input gear on the second motor shaft, and the first reduction gear mechanism.
In Paragraph 11, The above third reduction gear mechanism A second idler axis positioned parallel to the first idler axis; The first output gear fixed to the first motor shaft; Input gear fixed to the second motor shaft; and A third idler gear rotatably disposed on the second idler shaft and externally meshing with the first output gear and the input gear, respectively; A drive unit for an electric vehicle including

Description

Driving device for electric vehicles The present invention relates to a drive unit for an electric vehicle, and more specifically, to a drive unit for an electric vehicle that combines two motors and two or three reduction gear units to appropriately perform its role according to the driving range of the electric vehicle. Generally, drive systems for electric vehicles (commonly referred to as e-axles, hereinafter referred to as drive systems) require high efficiency, high performance (higher torque × higher output), and low-cost design and manufacturing within a limited mounting space. Depending on whether they are applied as the primary drive source in two-wheel drive (2WD) or four-wheel drive (4WD) electric vehicles, or as an auxiliary drive source in four-wheel drive (4WD) electric vehicles, they are equipped with high-cost, high-efficiency motor systems or low-cost, low-efficiency or non-rare-earth motor systems. When such a drive unit is applied as the primary drive source, it is configured as a single drive platform under conditions that satisfy installability while focusing on low cost and high efficiency to improve the driving range and energy efficiency of electric vehicles, thereby responding to multiple required performance specifications by changing only some design specifications. In particular, when applying a conventional motor system equipped with rare-earth permanent magnets as a drive unit, there are limitations in achieving both high efficiency and low cost within a limited mounting space through simple electrical design changes. Furthermore, if torque and output performance exceeding any arbitrary limit are required, the efficiency gains and effects obtainable relative to the input cost decrease rapidly. Meanwhile, when a drive unit is applied as an auxiliary drive unit, the focus is placed on low-cost development rather than high-efficiency development under conditions that satisfy vehicle performance. This involves adopting a motor system equipped with an inverter in which an expensive power module is replaced with a low-cost type in the power conversion section of the drive unit applied as the main drive unit, or adopting a motor system equipped with a motor of the same type or a non-rare earth motor that has lower cost and lower efficiency characteristics than the motor equipped with rare earth permanent magnets in the main drive unit. However, when a motor equipped with a permanent magnet is adopted to configure the driving source of a four-wheel drive (4WD) electric vehicle, when driving in two-wheel drive (2WD) mode using only the main driving source, a significant no-load drag (loss) caused by the motor equipped with a permanent magnet occurs on the wheel where the auxiliary driving source is located, and as a result, there is a problem of reduced driving range and energy efficiency of the four-wheel drive (4WD) electric vehicle. To solve this problem, a separate disconnect device must be added between the differential gear side of the auxiliary drive source and the wheel, but this results in another problem that causes an increase in input costs and weight. On the other hand, there is a disadvantage that in order to implement an auxiliary drive source with the same torque and output specifications using a motor system equipped with a non-rare earth motor, an increase in size, volume, or cooling capacity is unavoidable compared to a drive unit adopting a motor equipped with a rare earth permanent magnet. Furthermore, when a drive unit implemented with a motor equipped with rare-earth permanent magnets requires additional or improved hill-climbing and towing capabilities beyond basic performance requirements, conventional drive units inevitably necessitate overall design changes to the reduction gear mechanism, motor unit, and power conversion unit; consequently, there is a problem in that the efficiency gain and effectiveness relative to the input cost are reduced. The matters described in this background technology section are written to enhance understanding of the background of the invention and may include matters that are not prior art already known to those skilled in the art to which this technology belongs. These drawings are intended for reference to explain exemplary embodiments of the present invention, and therefore, the technical concept of the present invention should not be interpreted as being limited to the attached drawings. FIG. 1 is a configuration diagram of a drive unit for an electric vehicle according to a first embodiment of the present invention. FIG. 2 is a configuration diagram of a drive unit for an electric vehicle according to a second embodiment of the present invention. FIG. 3 is a configuration diagram of a drive unit for an electric vehicle according to a third embodiment of the present invention. FIG. 4 is a configuration diagram of a drive unit for an electric vehicle according to the fourth embodiment of the present invention. The drawings re