Field of the disclosure

The disclosure relates generally to electric vehicles. More particularly, the disclosure relates to an electric car.

Background

Electric cars have many advantages over traditional cars provided with a combustion engine. In most cases, the electric energy used by an electric car can be produced with smaller pollution emissions and with smaller consumption of non-renewable natural resources than in a case where a combustion engine is used for converting on-board fuel energy into propulsion. Furthermore, electric cars are typically capable of recovering braking energy whereas in traditional cars provided with combustion engines the braking energy is wasted as heat. An electric car comprises typically one or more electric drives for driving one or more wheels of the electric car. An electric drive comprises an electric machine connected directly or via a gear to one or more wheels and a converter system for converting direct voltage of a battery system into voltages suitable for the electric machine. The converter system is advantageously two directional so as to allow the electric machine to operate not only as a motor for providing the propulsion but also as a generator for charging the battery system during braking. It is also possible that an electric car is a hybrid car which comprises a combustion engine in addition to an electrical propulsion system.

An inconvenience related to electric cars is the weight and the space requirement of a battery system. In a typical arrangement, a battery system is placed in a room under the floor of the trunk of an electric car. This arrangement makes it possible that the center of gravity of the electric car can be kept low but an inconvenience related to this arrangement is that the center of gravity is located in the aft part of the electric car, which causes adverse oversteering tendency because the battery system may act as a pendulum mass in road bends. Furthermore, in some cases e.g. in conjunction with electric racing cars, there can be a requirement that a battery module of an electric car has to be able to be changed quickly to another battery module. Yet furthermore, there can be a safety requirement that a battery module should be able to be removed from an electric car during driving.

Summary The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.

In accordance with the invention, there is provided a new electric car that can be, for example but not necessarily, an electric racing car. An electric car according to the invention comprises: - a chassis constituting a longitudinal tunnel in the longitudinal direction of the electric car,

- one or more electric drives for driving one of more wheels of the electric car,

- fastening devices for holding an elongated battery module in the longitudinal tunnel so that the longitudinal tunnel is arranged to act as a room for the elongated battery module, the fastening devices comprising one or more quick couplers controllable from a cockpit of the electric car so as to enable a driver to release the elongated battery module, and

- one or more electric connectors for electrically connecting the one or more electric drives to the elongated battery module.

As the battery module is located in the longitudinal tunnel of the chassis, the center of gravity of the electric car can be kept low. Furthermore, the center of gravity of the electric car can be located on the middle portion of the electric car. Thus, the weight of the battery module does not cause such adverse oversteering tendency as in a case where a battery module is located in the aft part of an electric car.

The battery module may comprise for example: - one or more electrically separate battery elements each comprising one or more electrically interconnected battery cells,

- one or more electric connectors for electrically connecting the one or more battery elements to one or more electric drives of the electric car, and

- an elongated casing containing the one or more battery elements and shaped to be suitable for a longitudinal tunnel of the chassis of the electric car.

A number of exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.

Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in connection with the accompanying drawings.

The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in the accompanied dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality. Brief description of figures

Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below with reference to the accompanying drawings, in which: figures 1 a, 1 b, and 1 c illustrate an electric car according to an exemplifying and non-limiting embodiment of the invention, and figures 2a and 2b illustrate a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention. Description of exemplifying embodiments

The specific examples provided in the description below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated. Figures 1 a, 1 b, and 1 c illustrate an electric car according to an exemplifying and non-limiting embodiment of the invention. Figure 1 a shows a schematic bottom view of the electric car, figure 1 b shows a front view of the electric car, and figure 1 c shows a back view of the electric car. The viewing directions related to figures 1 a-1 c are illustrated by a coordinate system 199. The electric car comprises bodywork 101 where a chassis 1 1 1 is arranged to constitute a longitudinal tunnel 106 on the longitudinal center line of the chassis 1 1 1 . An advantage of the longitudinal tunnel 106 is that it increases the mechanical stiffness of the bodywork and thereby the mechanical stiffness of the electric car. The electric car comprises electric drives 102, 103, 104, and 105 for driving the wheels of the electric car. In figures 1 a and 1 b, one of the wheels is denoted with a reference number 1 13. The electric car comprises fastening devices 107 for holding an elongated battery module 1 10 in the longitudinal tunnel 106 so that the longitudinal tunnel is arranged to act as a room for the battery module 1 10. The electric car comprises electric connectors 108a, 108b, 108c, and 108d for electrically connecting the electric drives 102-105 to the battery module 1 10. Correspondingly, the battery module 1 10 comprises electric connectors that match the electric connectors of the electric car. In this exemplifying case, the electric car and the battery module comprise separate electric connectors for each of the electric drives. It is also possible that the electric car, and correspondingly the battery module, comprises only one electric connector that comprises a sufficient number of electrical poles for connecting the electric drives 102-105 to the battery module 1 10. Advantageously, the battery module 1 10 further comprises a charging connector for receiving charging current from an external electric system. In figure 1 c, the charging connector is denoted with a reference number 123. It is also possible that the electric car comprises a charging connector and the charging current is conducted to the battery module via the electric car but an inherent advantage of the charging connector 123 of the battery module is that the battery module can be charged also when the battery module is separate from the electric car.

In the exemplifying electric car illustrated in figures 1 a-1 c, each of the electric drives 102-105 comprises an electric machine for driving one of the wheels and a converter system for converting direct voltage of the battery module into voltages suitable for the electric machine. In figure 1 a, the electric machine of the electric drive 102 is denoted with a reference number 1 14. In this exemplifying case, each electric machine comprises many separate stator windings which are supplied by separate converters of the converter system under consideration. In figure 1 a, one of the converters of the converter system of the electric drive 102 is denoted with a reference number 1 15. The battery module 1 10 comprises electrically separate battery elements each comprising one or more electrically interconnected battery cells. Each of the electric connectors 108a - 108d comprises advantageously as many electrical pole pairs as there are converters in the corresponding one of the electric drives 102-105. In this case, each of the converters can be supplied by a battery element which is electrically separate from the other battery elements supplying the other converters. The modular arrangement where each electric machine comprises many separate stator windings that are electrically insulated from each other and supplied by separate converters and battery elements makes it possible to achieve high power so that the maximum voltage as well as the maximum current can still be relatively low. Furthermore, the modularity of the kind described above improves the fault tolerance of the electric drives 102-105.

In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least four electrical pole pairs for connecting to at least four electrically separate battery elements. In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least ten electrical pole pairs for connecting to at least ten electrically separate battery elements. In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least fifteen electrical pole pairs for connecting to at least fifteen electrically separate battery elements. In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least twenty electrical pole pairs for connecting to at least twenty electrically separate battery elements. In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least fifty electrical pole pairs for connecting to at least fifty electrically separate battery elements. In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least one hundred electrical pole pairs for connecting to at least one hundred electrically separate battery elements. In an electric car according to an exemplifying and non-limiting embodiment of the invention, each of the electric connectors 108a - 108d comprises at least 250 electrical pole pairs for connecting to at least 250 electrically separate battery elements.

The fastening devices 107 for holding the battery module 1 10 in the longitudinal tunnel 106 may comprise for example one or more quick couplers that are advantageously controllable from the car cockpit so as to enable a driver to release the battery module 1 10 during driving. The driver may want to remove the battery module 1 10 from the electric car for example when a dangerous situation is about to develop. Especially in conjunction with electric racing cars, the quick couplers can be controllable also outside the car cockpit so as to allow for example maintenance staff to change the battery module to another one during a pit stop. In some cases it is, however, also possible that the fastening devices 107 comprise traditional bolts.

In an electric car according to an exemplifying and non-limiting embodiment of the invention, the longitudinal tunnel 106 comprises a bottom plate so that the longitudinal tunnel constitutes a tubular room for the battery module 1 10. The bottom plate is shown in figures 1 b and 1 c and the bottom plate is denoted with a reference number 1 12. The bottom plate is not shown in figure 1 a. In this case, the longitudinal tunnel 106 is advantageously open at the front part of the electric car so as to allow the battery module 1 10 to be installed in the longitudinal tunnel and to be removed from the longitudinal tunnel with longitudinal movements via the front part of the electric car. In this case, the battery module 1 10 can be removed from the electric car during driving by releasing the fastening devices 107 and by braking sufficiently strongly so that the battery module 1 10 continues its travel by its own momentum. In the exemplifying electric car illustrated in figure 1 a-1 c, the longitudinal tunnel 106 is open also at the rear end of the electric car so as to allow the battery module 1 10 to be installed in the longitudinal tunnel and to be removed from the longitudinal tunnel with longitudinal movements via the rear end of the electric car.

In an electric car according to an exemplifying and non-limiting embodiment of the invention, the longitudinal tunnel is open downwardly so as the enable the battery module 1 10 to be dropped off from the longitudinal tunnel.

The exemplifying electric car illustrated in figures 1 a-1 c comprises only the electric propulsion system and there is no combustion engine. An electric car according to another exemplifying and non-limiting embodiment of the invention is a hybrid car comprising a combustion engine in addition to the electrical propulsion system. Figures 2a and 2b illustrate a battery module 210 suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention. Figure 2a shows a top view of the battery module 210 and figure 2b shows a view of the section taken along a line A-A shown in figure 2a. The section plane is parallel with the xz-plane of a coordinate system 299. The battery module 210 comprises electrically separate battery elements each comprising one or more electrically interconnected battery cells. In figure 2b, one of the battery elements is denoted with a reference number 216. The battery module 210 comprises an electric connector 218 for electrically connecting the battery elements to one or more electric drives of an electric car. In this exemplifying case, the electric connector 218 comprises a sufficient number of electrical poles for providing electrical connections to the electric drives of the electric car. It is also possible that there is more than one electric connector for providing the electrical connections to the electric drives of the electric car.

The battery module 210 comprises an elongated casing 217 containing the battery elements and shaped to be suitable for a longitudinal tunnel of the chassis of the electric car. For safety reasons, the battery elements are located advantageously in the middle region 219 of the elongated casing 217 so that the end regions 220 and 221 of the elongated casing 217 are free from the battery elements. The end regions 220 and 221 are advantageously arranged to contain impact protection material 222 for protecting the battery elements in a possible crash situation of the electric car. The impact protection material 222 can be for example foamed polyurethane or some other suitable material for absorbing impact energy. Advantageously, the battery module 210 further comprises an electric connector 123 for receiving charging current from an external electric system.

In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the number of the electrically separate battery elements is at least sixteen. In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the number of the electrically separate battery elements is at least forty. In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the number of the electrically separate battery elements is at least sixty. In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the number of the electrically separate battery elements is at least eighty. In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the number of the electrically separate battery elements is at least two hundred. In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the number of the electrically separate battery elements is at least four hundred. In a battery module suitable for an electric car according to an exemplifying and non- limiting embodiment of the invention, the number of the electrically separate battery elements is at least one thousand. In a battery module suitable for an electric car according to an exemplifying and non-limiting embodiment of the invention, the ratio of the length L of the elongated casing 207 to the width W of the elongated casing is on a range from 5 to 20 and the ratio of the length of the elongated casing to the height H of the elongated casing is on a range from 5 to 20. The length L, the width W, and the height H of the elongated casing 207 are illustrated in figures 2a and 2b.

The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.