Electric car

Abstract

The invention relates to an electric car with (a) a first axle (12), (b) a second axle (14), (c) an electric motor (18) for driving at least one of the axles, which has an electric motor overall height (h.sub.M)t, and (d) a battery (22) for supplying the electric motor (18) with electrical energy, which has a battery overall height (h.sub.B), wherein (e) the electric motor overall height (h.sub.M) corresponds to the battery overall height (h.sub.B). According to the invention, (f) the electric motor (18) is composed of at least two electric motor modules (38.1, 38.2) and (g) the electric motor modules (38.1, 38.2) are arranged one behind the other in relation to a motor rotational axis (D.sub.18); (h) the electric motor modules (38.1, 38.2) have a common rotor shaft (4) or coupled rotor shafts (41); (i) the electric motor (18) and the battery are arranged at the same height; and (j) a battery mass centre of gravity (S.sub.22) of the battery lies in a central third (Q) between the axles (12, 14).

Claims

1. An electric car, comprising: (a) a first axle, (b) a second axle, (c) an electric motor for driving at least one of the first and second axles which has an electric motor overall height (h.sub.M), and (d) a battery for supplying the electric motor with electrical energy, said battery having a battery overall height (h.sub.B), wherein (e) the electric motor overall height (h.sub.M) corresponds to the battery overall height (h.sub.B), wherein (f) the electric motor is composed of at least two electric motor modules, (g) the at least two electric motor modules are arranged one behind the other in relation to a motor rotational axis (D.sub.18), (h) the at least two electric motor modules have a common rotor shaft or coupled rotor shafts, (i) the electric motor and the battery are arranged at the same height, and (j) a battery mass centre of gravity (S.sub.22) of the battery lies in a central third between the first and second axles.

2. The electric car according to claim 1, wherein (a) the electric motor is an external rotor motor, (b) a rotor of the external rotor motor has a T-shaped drum, and (c) a stator of the external rotor motor comprises at least one coil package which is arranged between the T-shaped drum and the common rotor shaft or coupled rotor shafts.

3. The electric car according to claim 2, wherein the T-shaped drum is T-shaped in a radial direction in relation to a cross-section.

4. The electric car according to claim 2 wherein the T-shaped drum has a form-fit contour, (b) the common rotor shaft or coupled rotor shafts has a form-fit contour, and (c) the T-shaped drum is connected to the common rotor shaft or coupled rotor shafts by the form-fit contours such that a connection created therebetween is torque-proof.

5. The electric car according to claim 2 wherein (a) the stator is connected to a base body via a cap and comprises at least two or more coil packages, and (b) the at least two or more coil packages are fixed to the cap of the stator, (c) wherein the cap is reversibly fixed to the base body.

6. The electric car according to claim 1 wherein an electric motor mass centre of gravity (S.sub.18) of the electric motor lies in the central third between the first and second axles.

7. The electric car according to claim 1 wherein the battery features at least two battery units, and the motor rotational axis (D.sub.18) extends between the at least two battery units.

8. The electric car according to claim 1, further comprising: (a) a differential, and (b) a gearbox arranged in a torque flow between the motor and the differential.

9. The electric car according to claim 8, further comprising: (a) a second differential, and (b) a second gearbox arranged in a torque flow between the motor and the second differential.

10. The electric car according to claim 1, wherein as an internal rotor, the electric motor has a rotor shaft with permanent magnets, and the rotor shaft comprises grooves that extend in a longitudinal direction, the permanent magnets being arranged in said grooves.

11. The electric car according to claim 1, further comprising: a second electric motor which is composed of at least two second electric motor modules, wherein the at least two second electric motor modules feature a common second rotor, and wherein the rotor shaft and the common second rotor extend parallel to one another.

12. The electric car according to claim 1, further comprising: (a) a second electric motor, (b) a third electric motor, and (c) a fourth electric motor, (d) wherein each electric motor drives a wheel.

13. The electric car according to claim 1 wherein the electric motor mass centre of gravity (S.sub.18) is situated in a central longitudinal quarter.

14. An electric motor for an electric car according to claim 1, wherein (a) the electric motor is an external rotor motor, and wherein the electric motor comprises (b) a stator which has at least one coil package, and (c) a rotor which comprises a drum which radially surrounds the at least one coil package as a sleeve.

15. The electric motor according to claim 14, wherein the drum is T-shaped in the radial direction in relation to a cross-section.

16. The electric motor according to claim 14 wherein the drum has a form-fit contour, (b) the rotor shaft has a form-fit contour, and (c) the drum is connected to the rotor shaft by the form-fit contours such that the connection is torque-proof.

17. The electric motor according to claim 14 wherein the stator is connected to a base body via a cap and comprises at least two or more coil packages, and the two or more coil packages are fixed to the cap of the stator, wherein the cap is reversibly fixed to the base body.

Description

(1) In the following, the invention will be explained in more detail by way of the attached figures. They show

(2) FIG. 1a a three-dimensional partial view of an electric vehicle according to the invention, according to first embodiment,

(3) FIG. 1b the electric vehicle according to FIG. 1a in a sectional view from behind,

(4) FIG. 2 an electric vehicle according to a second embodiment,

(5) FIG. 3 an electric vehicle according to the invention, according to a third embodiment,

(6) FIG. 4 an electric vehicle according to the invention, according to a fourth embodiment,

(7) FIG. 5 an electric vehicle according to the invention, according to a fifth embodiment,

(8) FIG. 6 an electric vehicle according to the invention, according to a sixth embodiment,

(9) FIG. 7 with the partial FIGS. 7a and 7b as isometric views and partial FIG. 7c as a sectional view of an electric motor as an internal rotor for an electric vehicle according to the invention, and

(10) FIG. 8 with the partial FIGS. 8a and 8b as isometric views and partial FIGS. 8c and 8d as sectional views of an electric motor as an external rotor for an electric vehicle according to the invention.

(11) FIG. 1a depicts an electric vehicle 10 according to the invention in the form of an electric car, which comprises a first axle 12 in the form of a front axle and a second axle 14 in the form of a rear axle. Wheels 16.1, 16.2 are fixed to the first axle 12; wheels 16.3, 16.4 are fixed to the second axle 14. An electric motor 18 drives the wheels 16.1, 16.2 of the first axle 12 via a differential gearbox 20, which may also be referred to as a differential.

(12) The electric motor 18 is supplied with power from a battery 22. The battery 22 comprises at least two—in the present case eight—battery units 24.1, 24.2, . . . , 24.8.

(13) It is clear to see that a motor rotational axis D.sub.18 extends between the battery units 24.1, 24.3, 24.5, 24.7 on one side and 24.2, 24.4, 24.6 and 24.8 on the other. A mass m.sub.r of the battery units 24.1, 24.3, 24.5 and 24.7 arranged to the right of the motor rotational axis D.sub.18 corresponds to a mass m.sub.l of the battery elements to the left of the motor rotational axis D.sub.18, i.e. in the present case of the battery elements 24.2, 24.4, 24.6 and 24.8.

(14) The feature that the two masses m.sub.r, m.sub.l correspond to each other should be understood particularly to mean that the two masses deviate from one another by a maximum of 20%, preferably a maximum of 15%.

(15) The electric vehicle 10 has a vehicle floor 25. In the present embodiment, both the battery 22 and the electric motor 18 are mounted on the vehicle floor 25. The electric vehicle 10 also has components that are not depicted, such as an outer casing, in particular made of sheet metal, seats and a steering system.

(16) FIG. 1a also demonstrates that the electric motor mass centre of gravity S.sub.18 is situated in a central longitudinal quarter LQ, especially in a longitudinal fifth. In general, it is beneficial for the electric motor mass centre of gravity S.sub.18 to be situated as close as possible to a centre line M.

(17) It should also be recognised that all battery modules 24 are—and thus that the battery 22 is—arranged between the axles 12, 14. However, it is also possible that a part of the battery modules 24.j (j=1, 2, . . . , number of battery modules) is arranged on the other side of the axles; however, it is beneficial if at least 80% by weight of the mass of the battery modules 24.j is arranged between the axles. In the present embodiment, the structural length L.sub.18 of the electric motor 18 is 0.4 times the wheelbase A.

(18) FIG. 1b shows the electric vehicle 10 in a view from behind. It should be recognised that an electric motor overall height h.sub.M corresponds to a battery overall height h.sub.B. The electric motor overall height h.sub.M is the height of the conceived cuboid Q.sub.1 of minimal volume, which encloses 90% of the mass of the battery 22. FIG. 1b also shows a body 26 of the electric vehicle 10. A driver's seat 30 and a front passenger's seat 32 are also depicted, both of which are arranged on an even floor 34 of a passenger area 36.

(19) It should be noted that the electric motor mass centre of gravity S.sub.18 is at a height H.sub.18, which corresponds to a height H.sub.22 of the battery mass centre of gravity S.sub.22.

(20) FIG. 2 depicts a second embodiment of an electric vehicle 10 according to the invention, wherein the electric motor 18 is composed of three electric motor modules 38.1, 38.2, 38.3 that are coupled one behind the other. All three electric motor modules 38.1, 38.2, 38.3 are structurally identical and comprise rotor shafts 41 that are coupled with one another. It is possible, but not necessary, for each electric motor module 38.i (i=1, . . . N; N: number of electric motor modules) to have its own rotor element—as is the case in the present embodiment—wherein the individual rotor elements are connected to one another, thereby forming the rotor 39. It is possible that the rotor is designed to be free of joints. The electric motor modules 38.i are structurally identical.

(21) FIG. 2 shows that the electric vehicle 10 features an additional gearbox 42 between the differential gearbox 20 and the electric motor 18. This renders possible a simple adjustment of the rotor speed to match the wheel speed. In particular, the electric motor may be driven at higher speeds than without the gearbox 42, wherein said gearbox preferably refers, accordingly, to a reduction gearbox.

(22) In the present embodiment, the structural length L.sub.18 of the electric motor 18 is also 0.4 times the wheelbase A.

(23) FIG. 3 shows a further embodiment of an electric vehicle 10 according to the invention; the coupled rotor shafts 41 of the electric motors 18 are rigidly connected to both the differential 20 and a second differential 44. In the present case, the end of the coupled rotor shaft 41 is connected to the second differential 44 via a second gearbox 46.

(24) Unlike in the embodiment according to FIG. 2, the electric motor 18 has five electric modules 38.i (N=5). A maximum torque M.sub.max of the electric motor according to FIG. 2 is M.sub.max=300 Nm. Conversely, the maximum torque M.sub.max for the electric vehicle according to FIG. 3 is M.sub.max=500 Nm. It should be recognised that the maximum torque increases in a linear fashion with the number of electric motor modules N.

(25) In this embodiment, the structural length L.sub.18 of the electric motor 18 is 0.7 times the wheelbase A.

(26) FIG. 4 shows a fourth embodiment of an electric vehicle 10 according to the invention. The electric motor 18 features several stator coil packages 48.1, . . . , 48.N.sub.48 (N.sub.48: number of coil packages). Each stator coil package 48.j (j=1, . . . , N.sub.48) can be removed without having to remove the continuous rotor shaft 40. It should be recognised that the continuous rotor shaft 40 comprises grooves 50.1, 50.2, into which permanent magnets are inserted; said magnets are not depicted for the sake of clarity. The electric motor according to FIG. 4 is an internal rotor.

(27) FIG. 5 depicts a fifth embodiment of an electric vehicle 10 according to the invention, which has a second electric motor 18′. The second electric motor comprises three electric motor modules 38′.1, 38′.2 and 38.'3. The two electric motor modules 38′.1, and 38.'3 are structurally identical. The continuous rotor shaft 40′ runs, in the technical sense, parallel to the continuous rotor shaft 40, i.e. small deviations of, for instance, a maximum of 5° are tolerable. Both continuous rotor shafts 40 and 40′ and thereby the allocated motor rotational axes D.sub.18, D′.sub.18 also extend along a longitudinal axis L of the electric vehicle 10, as is the case in the remaining embodiments.

(28) The two electric motors 18, 18′ collectively drive a first coupling mechanism 52 and a second coupling mechanism 54. The first coupling mechanism 52 is rigidly coupled with the first differential 20; the second coupling mechanism 54 is rigidly connected to the second differential 44.

(29) FIG. 6 depicts a sixth embodiment of an electric vehicle 10 according to the invention in which 4 electric motors 18.1, 18.2, 18.3 and 18.4 are used. Here, the first electric motor 18.1 drives the first wheel 16.1 and the second electric motor 18.2 drives the second wheel 16.2. The third electric motor 18.3 drives the third wheel 16.3 and the fourth electric motor 18.4 drives the fourth wheel 16.4. The electric vehicle 10 also features a schematically depicted motor control system 58, which is connected to all electric motors and the battery. The motor control system 58 is designed to control all electric motors 18.1, . . . , 18.4 in such a way that, when the electric vehicle 10 is cornering, the different angular speeds of the wheels give rise to adapted speeds of the respective electric motors, such that the skid on all wheels 16.i is the same size and ideally has a value of zero. It is possible that each electric motor is composed of two or more structurally identical electric motor modules.

(30) In all the electric vehicles shown, a battery mass centre of gravity S.sub.22 (see FIG. 1a) lies between the axles 12, 14. In the embodiments shown, a distance of the battery mass centre of gravity S.sub.22 from a vehicle mass centre gravity point S.sub.10 is at most a quarter of a wheelbase A of the two axles 12, 14. An electric motor mass centre of gravity S.sub.18 is also situated close to the vehicle mass centre of gravity S.sub.16, specifically in a central quintile Q along the longitudinal axis L between the axles 12, 14.

(31) FIG. 1b demonstrates that the battery 22, in particular its galvanic cells, are not situated underneath the electric motor 18. In other words, all battery modules 24.i are arranged to either the left or the right of—but not above or below—the electric motor 18 in relation to the longitudinal axis L.

(32) FIG. 7a shows two electric motor modules 38.1. and 38.2, which lie one behind the other, in the version that features an internal rotor and a shaft bearing 60.1, 60.2, by way of which the continuous rotor shaft 40 is mounted and fixed to the vehicle floor 25 (see FIG. 4, 5). It should be recognised that the electric motor modules 38.1, 38.2 can be removed by means of detachable fixing elements, in the present case in the form of screws 62.1, . . . .

(33) All electric motor modules 38.k (k=1, 2, . . . number of electric motor modules) are electrically commutated, permanently excited synchronous motors.

(34) In a vertical cut through an electric motor module of the internal rotor version, FIG. 7b demonstrates that permanent magnets 64.1 . . . are inserted in the grooves 50.1, 50.2 . . . of the continuous rotor shaft 40, wherein said permanent magnets are induced to rotation by the coil package 48.

(35) FIG. 7c depicts a lateral view of the electric motor modules 38.1 and 38.2 of the internal rotor version.

(36) FIG. 8 shows two electric motor modules 38.1 and 38.2, which lie one behind the other, in the version that features an external rotor, the stator 66 of which features a base body 68 as well as a first cap 70.1 and a second cap 70.2. The caps 70.1, 70.2 are reversibly fixed to the base body 68 using screws 62.1, 62.2, . . . , 62.8. Each cap 70.i is securely connected to at least one stator coil package.

(37) FIG. 8b depicts a to-scale view of the rotor 39, which comprises a shaft 72 in form of a hollow shaft, as do the remaining partial figures of FIG. 8. The shaft 72 features an outer toothing 74; a drum 78 lies on said outer toothing by way of an inner toothing 76. The drum 78 forms a T-shaped outer section of the rotor 39. It should be recognised that the rotor 39 also features a second drum 78′. Of course, further rotor houses may be provided. For example, the electric motor comprises at least three drums. In FIG. 8b, the permanent magnets of the rotor are not depicted for the sake of clarity.

(38) FIG. 8c shows a cut through the electric motor module 38.1 of the external rotor version. It should be noted that the permanent magnets 64 are arranged on an inner side of a cylinder barre/portion 80 of the drum 78. They are moved by the stator coil package 48. For instance, the permanent magnets 64.i are inserted in grooves in the radially inward side of the cylinder barre/portion 80.

(39) FIG. 8d depicts a sectional view through the electric motor modules 38.1 and 38.2 of the external rotor version with the T-shaped drums 78 and 78′. It should be recognised that coils 82.i are rigidly mechanically connected and also thermally connected to the cap 70 of the stator 66. In other words, at least one coil package 48, which comprises the coils 82.i, is fixed to the cap 70 of the stator 66 in such a way that the waste heat from the coil package 48 is actively or passively discharged during operation of the electric vehicle.

REFERENCE LIST

(40) 10 electric vehicle 12 first axle 14 second axle 16 wheels 18 electric motor 20 differential 22 battery 24 battery module 25 vehicle floor 26 body 28 drive shaft 30 driver's seat 32 front passenger's seat 34 floor 36 passenger area 38 electric motor module 39 rotor 40 rotor shaft, continuous 41 rotor shaft, coupled 42 gearbox 44 second differential 46 second gearbox 48 stator coil package 50 groove 52 first coupling mechanism 54 second coupling mechanism 56 electric motor unit 58 motor control system 60 shaft bearing 62 screws 64 permanent magnet 66 stator 68 base body 70 cap 72 shaft 74 outer toothing 76 inner toothing 78 drum 80 cylinder barre/portion 82 coil A wheelbase D.sub.18 motor rotational axis h.sub.M electric motor overall height h.sub.B battery overall height i running index running index L longitudinal axis m.sub.l mass of the battery elements to the left of the motor rotational axis m.sub.r mass of the battery elements to the right of the motor rotational axis M.sub.max maximum torque N.sub.38 number of electric motor modules N.sub.48 number of stator packages Q central percentile LQ longitudinal quarter S.sub.22 battery mass centre of gravity S.sub.18 electric motor macs centre of gravity S.sub.10 vehicle mass centre of gravity