Electric vehicle utilizing kinetic energy efficiently and effectively

Abstract

ENERGY SAVING, SIMPLIFICATION, COST REDUCTION, AND HIGH RELIABILITY OF ELECTRIC VEHICLE SOLUTION: Instead of an electric vehicle of a regenerative cooperative braking system in which kinetic energy of a traveling vehicle is regenerated during deceleration of the vehicle and stored in a battery (or a large-capacity capacitor) to be used as an energy source for subsequent traveling, the kinetic energy of the vehicle is directly utilized for deceleration traveling of the vehicle by performing deceleration traveling mainly by inertia traveling from a point within an inertia travelable distance upstream of a target point of deceleration / stop corresponding to a vehicle traveling speed toward the target point of deceleration / stop; To achieve simplification, cost reduction, and high reliability of vehicle configuration / control by dispensing with a regenerative power storage battery (or a large-capacity capacitor), and reducing battery management accuracy for maintaining battery performance by reducing a high charge / discharge load to a vehicle driving power storage battery.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This electric vehicle is simpler in configuration and control and more efficient in utilizing kinetic energy than conventional electric vehicles that use cooperative regenerative braking, which regenerates the kinetic energy of a moving vehicle when the vehicle decelerates and utilizes it for subsequent driving. [Background technology]

[0002] Conventionally, electric vehicles, including hybrid vehicles, have used regenerative braking as a way to effectively utilize the vehicle's kinetic energy. However, this regenerative braking requires a battery or a large-capacity capacitor to store the regenerative energy, and the battery that stores the regenerative energy must be able to withstand the frequent, rapid charging and discharging of the power generated by kinetic energy regeneration under limited battery conditions. These factors have a significant impact on the price and lifespan of the vehicle, and ultimately on the widespread adoption of vehicles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2011-46272 [Patent Document 2] Patent Publication No. 2014-000942 [Patent Document 3] Patent Publication No. 2017-124807 [Patent Document 4] Patent Publication No. 2022-183407 Summary of the Invention [Problem to be solved by the invention]

[0004] use In contrast to the kinetic energy regeneration methods / devices used in the conventional electric vehicles described above, this invention aims to solve the above problems by providing a deceleration / braking method using kinetic energy that does not require kinetic energy regeneration, has high kinetic energy utilization efficiency, does not require a battery for storing regenerated energy, and simplifies battery management, thereby simplifying vehicle configuration / control. [Means for solving the problem]

[0005] The kinetic energy possessed by a vehicle while it is running is not regenerated during deceleration and used as part of the subsequent running energy, but is directly used as an energy source during deceleration (Patent Document 3). In other words, the kinetic energy is used as energy to compensate for running resistance during deceleration, thereby improving the efficiency of kinetic energy utilization. Furthermore, when it comes to regenerating kinetic energy, the regenerative braking method lacks sufficient braking force, and as a solution to this problem, a regenerative cooperative braking method must be adopted. As a result, the efficiency of kinetic energy utilization decreases. Furthermore, when kinetic energy is regenerated, the frequency of battery charging and discharging increases, and the requirements for the battery state during charging and discharging become more complex and sophisticated, making battery management to maintain battery performance and lifespan a challenge; however, these problems can be alleviated by not performing regeneration. [Effects of the Invention]

[0006] By decelerating the vehicle mainly by coasting instead of regenerative braking, the vehicle's kinetic energy is effectively utilized. Also, because there is no need to store regenerative power, the requirements for battery management to efficiently utilize kinetic energy, such as upper limit battery charging voltage, lower limit discharge voltage, and cell balancing, are relaxed. This simplifies the vehicle configuration and control, and also reduces the risk of shortening battery life due to frequent rapid battery charging and discharging caused by kinetic energy regeneration. The present invention is applicable not only to HEVs (hybrid vehicles) and BEVs (electric vehicles), but also to FCEVs (fuel cell vehicles). [Brief explanation of the drawings]

[0007] [Figure 1] Illustration of coasting-based deceleration DETAILED DESCRIPTION OF THE INVENTION

[0008] Vehicles must be equipped with a car navigation system. The car navigation system must set a coasting start point in a map database within a distance that allows coasting, such as an intersection, upstream of a target deceleration / stop point corresponding to the vehicle's traveling speed. It must also specify in advance the coasting deceleration αi corresponding to the coasting start speed vc and the braking deceleration αb after coasting (Patent Document 1, Patent Document 2). [Example]

[0009] This will be explained using the explanatory diagram of deceleration traveling mainly in coasting in Figure 1. A vehicle traveling at a speed vc starts coasting (coasting at a coasting deceleration αi) at point A' within coasting possible distance point A upstream of target stopping point O, and when the vehicle reaches point O' upstream of point O at a speed vb while coasting, it transitions from coasting to braking at a braking deceleration αb, and then brakes to reach target stopping point O and stop (Patent Document 4). As a result, the vehicle coasts from speed vc to speed vb, and brakes from speed vb to 0 km / h, and the kinetic energy utilization efficiency η during this coasting is η=(vc 2 -vb 2 ) / vc 2 (Patent Document 2). Here, if vc=60km / h and vb=30km / h, the efficiency η of kinetic energy utilization by coasting is η=0.75. This coasting-based deceleration driving does not require a kinetic energy storage battery or electric double layer capacitor, and also does not require the complex battery management described above for efficiently regenerating kinetic energy. However, while regenerative braking can provide sufficient braking force by coordinating braking with friction braking (regenerative cooperative braking), this may not be possible when decelerating while coasting. To address this issue, by using electric braking in addition to friction braking, it is possible to obtain a braking force equal to or greater than that of regenerative cooperative braking in terms of total braking capacity. [Industrial Applicability]

[0010] This invention alleviates the problems of battery cost, weight and reliability that have been major obstacles to the widespread adoption of electric vehicles, including conventional hybrid vehicles. It also makes it possible to disconnect the drive body from the drive wheels when the vehicle is decelerating, thereby improving the efficiency with which the vehicle's kinetic energy is used for driving, thereby enabling energy savings and reduced CO2 emissions for the entire vehicle. In other words, the above effects will alleviate problems such as the efficiency of battery and kinetic energy utilization and battery reliability in conventional regenerative braking cooperative driving, and are expected to greatly contribute to the widespread use of electric vehicles. [Explanation of symbols]

[0011] In Figure 1, v: Vehicle speed αi: Coasting deceleration αb: Braking deceleration Point A: Point upstream of the target stopping point where coasting is possible Point A': Target stopping point upstream coasting start point Point B: braking start point at speed v O point: Target stopping point Point O': braking start point at speed v' AO: Coasting distance A'O': Coasting distance

Claims

[Claim 1] Instead of a regenerative cooperative braking system in which the kinetic energy of a moving vehicle is regenerated when the vehicle decelerates and stored in a battery or large-capacity capacitor to be used as an energy source for subsequent driving, this electric vehicle decelerates by mainly coasting from a point within a coasting distance upstream of the target point for deceleration and stopping that corresponds to the vehicle's traveling speed, toward the target point for deceleration and stopping.This system utilizes the kinetic energy of the vehicle directly to decelerate the vehicle, thereby achieving efficient use of kinetic energy, and by eliminating the need for a battery to store regenerative energy, it alleviates various problems in battery management for maintaining battery performance, thereby enabling simpler vehicle configuration and control, lower costs, and overall higher vehicle reliability.

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