Vehicle with a charging system for a battery

Abstract

Vehicle (1) with a charging system (2) for a battery (3), with a first electrical connection (4) for an alternating voltage, wherein the first connection (4) is connected to the charging system (2), with a second electrical connection (5) for a direct voltage, wherein the second connection (5) is connected to the charging system (2), wherein the charging system (2) comprises a converter (8), wherein the converter (8) is designed to convert the alternating voltage of the first connection (4) into a direct voltage for charging the battery (3), and wherein the converter (8) is designed to convert a level of a direct voltage, which is fed from the second connection (5) to the converter (8), and to pass it on to the battery (3), wherein the converter (8) is designed to convert the direct voltage of the battery (3) into an alternating voltage for driving an electric motor (9), wherein the electric motor (9) has three strands with three coils (81, 82, 83, 84, 85,86), wherein an electrical line (51, 67) of the second terminal (5) is connected to at least one of the three coils (81, 82, 83, 84, 85, 86), wherein each coil is divided into a first and second, series-connected partial coil (81, 82, 83, 84, 85, 86), wherein a center tap (91, 92, 93) is provided between the partial coils (81, 82, 83, 84, 85, 86) of at least one coil, wherein the electrical line (51, 67) of the second terminal (5) is connected to at least one center tap (91, 92, 93).

Description

[0001] The invention relates to a vehicle with a charging system for a battery according to claim 1 and a charging system according to claim 7.

[0002] US 2011 / 0 221 363 A1 discloses a vehicle with a charging system for a battery, with a first electrical connection for an alternating voltage, wherein the first connection is connected to the charging system, with a second electrical connection for a direct voltage, wherein the second connection is connected to the charging system, wherein the charging system comprises an inverter, wherein the inverter is designed to convert the alternating voltage of the first connection into a direct voltage for charging the battery, and wherein the inverter is designed to convert a level of a direct voltage that is fed from the second connection to the inverter and to pass it on to the battery, wherein the inverter is designed to convert the direct voltage of the battery into an alternating voltage for driving an electric motor with three phases.

[0003] DE 10 2012 205 972 A1 and US 2014 / 0 042 807 A1 disclose further prior art.

[0004] The object of the invention is to provide a vehicle with a charging system with increased flexibility when charging the battery.

[0005] The object of the invention is solved by patent claims 1 and 7.

[0006] Further embodiments are specified in the dependent claims.

[0007] One advantage of the described vehicle and charging system is that the battery can be charged with either an external AC voltage or an external DC voltage. Two connections are provided for this purpose, via which an AC voltage or a DC voltage can be connected to the vehicle's electrical system to charge the vehicle's battery.

[0008] In one embodiment, a switching unit is provided with which the external DC voltage, i.e., the second terminal, can be connected either to a converter or directly to the battery. The proposed solution achieves increased functionality, allowing various external voltage sources, in particular DC voltage sources, to be used to charge the battery via the converter, even if the voltage of the external voltage source does not match the voltage of the vehicle's battery.

[0009] The charging system for the battery has a first electrical connection for an alternating voltage, wherein the first connection is connected to the charging system. The charging system also has a second electrical connection for a direct voltage. The charging system comprises an inverter, wherein the inverter is designed to convert the alternating voltage of the first connection into a direct voltage for charging the battery, and wherein the inverter is designed to convert a level of a direct voltage that is fed from the second connection to the inverter and to pass it on to the battery. Furthermore, the inverter is designed to convert the direct voltage of the battery into an alternating voltage for driving an electric motor.

[0010] In one embodiment, the converter comprises a DC-DC converter and an inverter, wherein the DC-DC converter is designed to be operated in two directions, wherein the inverter is designed to be operated in two directions.

[0011] In a further embodiment, the inverter has two partial converters, wherein the two partial converters are connected in parallel and are each connected to a positive and negative supply line of the battery, wherein a first partial converter is connected to one input of each of the three coils, wherein the second partial converter is connected to one output of each of the coils.

[0012] In one embodiment, the electrical line of the second terminal is routed to each coil.

[0013] In one embodiment, the second terminal is connected to a switching unit, wherein the switching unit is connected to the converter via first connecting lines, wherein the switching unit is connected to the battery terminal via second connecting lines, and wherein the switching unit is designed to connect the second terminal either to the converter via the first connecting lines or to the battery terminal via the second connecting lines, depending on the electrical voltage at the second terminal.

[0014] In one version, the converter has three branches, each with two switches, with the branches being connected between the supply lines.

[0015] The invention is explained below with reference to the figures. Fig. 1 a schematic representation of a vehicle with a charging system for a battery, and Fig. 2 a schematic representation of an embodiment of a charging system.

[0016] Fig. 1 shows a vehicle 1, which is designed, for example, in the form of a motorcycle, a car, or a truck. The vehicle 1 has a charging system 2 for charging a battery 3 of the vehicle 1. The battery 3 can be designed as a high-voltage battery and, for example, provide electrical voltages in the range of up to 400 V or 800 V and more. Depending on the available external voltage source, a conversion of the voltage to charge the battery may or may not be necessary. External DC voltage sources can, for example, provide 110 volts, 230 volts, or 400 V. Thus, it may be necessary to transform the voltage of the external DC voltage source to a higher voltage in order to be able to charge the vehicle's battery. For charging the battery 3 via an external electrical voltage source, a first connection 4 is provided for connection to an external AC voltage source.Furthermore, a second terminal 5 is provided, via which the battery 3 can be charged using an external DC voltage source. In a simple embodiment, the second terminal 5 is connected directly to the battery or to connecting lines 61, 62 of the battery 3, or can be connected via appropriate switches.

[0017] Furthermore, an electronic circuit 8 is provided, which is connected to the connecting lines 61, 62 of the battery 3, i.e. to the poles of the battery 3, via lines 42. In addition, the circuit 8 is connected to coils of the electric motor 9 via further lines 37. The circuit 8 is connected to a charging management system 40 via a first control line 43. In addition, the charging management system 40 is connected to the electric motor 9 via a second measuring line 44. Furthermore, the charging management system 40 is connected to a second sensor unit 55 via a third measuring line 45. In addition, the sensor device 55 is connected to the first and / or second connecting lines 51, 52. In addition, the charging management system 40 is connected to the switching unit 7 via a second control line 46. The second connection 5 has a first and a second connecting line 51, 52, which are led to the switching unit 7.In addition, the connecting lines 61, 62 of the poles 11, 12 of the battery 3 are routed to the switching unit 7. Furthermore, a first and / or a second connecting line 53, 54 is routed from the electric motor 9 to the switching unit 7.

[0018] The charging management system 40 controls the switching position of the switching unit 7. In a first switching position of the switching unit 7, the connecting lines 51, 52 of the second connection 5 are connected directly to the connecting lines 61, 62 of the battery 3 in order to charge the battery via the second connection 5. The sensor unit 55 detects whether a voltage is present at the second connection 5 that is suitable for charging the battery 3. For example, the battery 3 can have a nominal voltage of 400 to 800 volts. If the direct voltage on the first and second connecting lines 51, 52 is at least the nominal voltage of the battery 3, the charging management system 40 controls the switching unit 7 in such a way that the first and second connecting lines 51, 52 are connected to the connecting lines 61, 62 of the battery 3 if charging is necessary. The charging management system 40 can, for example,via a further measuring line 41, which is connected to the connecting lines 61, 62. If charging is required, the first and second connecting lines 51, 52 are connected directly to the connecting lines 61, 62 of the battery 3 via a corresponding control of the switching unit 7 by the charging management system 40. If the charging management system 40 detects that the battery 3 is fully charged, the charging is terminated and the first and / or second connecting lines 51, 52 are disconnected from the connecting lines 61, 62 of the battery 3.

[0019] Furthermore, a voltage present at the connecting lines 51, 52 of the second terminal 5, which is however unsuitable for charging the battery due to the voltage being too low, can be transmitted via a corresponding switching position of the switching unit 7 via the first and second connecting lines 53, 54 to the electric motor 9, in particular to coils of the motor 9. The low DC voltage is transmitted via the motor 9 to the circuit 8 via further lines 37. In the circuit 8, which is designed as a converter, the excessively low voltage is transformed to a higher voltage and transmitted to the poles 11, 12 of the battery 3.

[0020] The first connection 4 is connected to the electric motor 9, in particular to coils of the motor 9, via further connecting lines 56, 57, 58. Depending on the selected embodiment, the first connection 4 can be connected to the electronic circuit 8 via an AC voltage filter 59. The first connection 4 is connected to the electronic circuit 8 via the electric motor 9. In addition, the charging management system 40 can use the second measuring line 44 to detect whether an AC voltage is present at the motor 9 via the further connecting lines 56, 57, 58 of the first connection 4, a voltage that would be suitable for charging the battery 3.If the charging management system 40 detects that an alternating voltage suitable for charging the battery is present on the further connecting lines 56 and thus also on the further lines 37, the charging management system 40 controls the circuit 8 via the control line 43 in such a way as to rectify the alternating voltage and to adjust the level of the rectified direct voltage so that charging of the battery 3 via the lines 42 is possible.

[0021] The electronic circuit 8 has a converter, wherein the converter is configured to convert the magnitude of a DC voltage supplied from the second terminal 5 to the converter and to transmit it to the battery in order to charge the battery. Furthermore, the converter can be configured to convert the AC voltage of the first terminal 4 into a DC voltage for charging the battery. Furthermore, the converter is configured to convert the DC voltage of the battery 3 into an AC voltage for driving an electric motor 9.

[0022] The electric motor 9 can, for example, be designed as a drive motor for driving the vehicle's wheels. However, the vehicle can also be designed as a hybrid vehicle, so that the motor is designed to drive the vehicle only partially or temporarily. However, the electric motor 9 can also be provided as an auxiliary motor for other components of the vehicle. The electric motor 9 is supplied with power from the battery 3 via the electronic circuit 8.

[0023] Fig. Figure 2 shows a detailed illustration of an embodiment of the charging system 2, wherein the battery 3 has two poles 11, 12 that can be connected to battery lines 61, 62 via a first and a second switch 13, 14, respectively. The first battery line 61 is connected to the positive pole 11 of the battery 3 and is also connected to a first supply line 63 of the electronic circuit 8. The second battery line 62 is connected to the negative pole 12 of the battery 3 and is connected to a second supply line 64 of the electronic circuit 8.

[0024] Furthermore, a second switching unit 70 is provided, which has a first additional line 65. The first additional line 65 is connected to the first supply line 63. In addition, a second additional line 66 is led from the second switching unit 70 to the second supply line 64. The first additional line 65 can be connected to the first connecting line 51 of the second connection 5 via a first additional switch 15. In addition, the second additional line 66 can be connected to the second connecting line 52 of the second connection 5 via a second additional switch 16. Furthermore, the second switching unit 70 has a third additional switch 17, which can connect the second additional line 66 to a third additional line 67 via a capacitor 19.In addition, a fourth further switch 18 is provided in the second switching unit 70, which can establish an electrically conductive connection between the first connecting line 51 and the third further line 67.

[0025] Motor 9 is shown only schematically, with three phases of motor 9 with three coils being shown. In the illustrated embodiment, the coils are each designed as two series-connected partial coils 81, 82, 83, 84, 85, 86. A center tap 91, 92, 93 is provided between each two coils.

[0026] The electronic circuit 8 represents a converter comprising a first sub-converter 21 and a second sub-converter 22. The inputs of the first sub-converter 21 are connected to the first and second supply lines 63, 64. The first sub-converter 21 has three outputs 31, 32, 33, each connected to a first, second, or third sub-coil 81, 82, 83 of the motor 9. The first sub-coil 81 is connected in series with the fourth sub-coil 84. The second sub-coil 82 is connected in series with the fifth sub-coil 85. The third sub-coil 83 is connected in series with the sixth sub-coil 86. The first and fourth partial coils, the second and fifth partial coils, and the third and sixth partial coils each represent a coil of the electric motor 9. A first center tap 91 is provided between the first and fourth partial coils 81, 84.The second center tap 92 is provided between the second and fifth partial coils 82, 85. The third center tap 93 is provided between the third and sixth partial coils 83, 86.

[0027] The inputs of the second sub-converter 22 are also connected to the first and second supply lines 63, 64. The fourth sub-coil 84 is connected to a further first output 34 of the second sub-converter 22. The fifth sub-coil 85 is connected to a further second output 35 of the second sub-converter 22. The sixth sub-coil 86 is connected to a further third output 36 of the second sub-converter 22. Furthermore, the first terminal 4 is connected to the first center tap 91 via a further connecting line 56 via a filter 59 and a isolating switching unit 60. In addition, a further connecting line 57 of the first terminal 4 is connected to the second center tap 92 via the filter 59 and the isolating switching unit 60. Furthermore, a further connecting line 58 of the first terminal 4 is connected to the third center tap 93 via the filter 59 and the isolating switching unit 60.The isolating switch unit 60 makes it possible to separate the further connecting lines 56, 57, 58 from the coils of the motor 9.

[0028] The first and second partial converters 21, 22 are designed to convert the direct current of the battery 3 into an alternating current in order to drive the electric motor 9 using the three coils. Furthermore, the partial converters 21, 22 can be used to convert the alternating current applied to the center taps 91, 92, 93 via the additional connecting lines 56, 57, 58 into a direct current with a corresponding voltage level in order to charge the battery 3 via the first and second supply lines 63, 64.

[0029] Furthermore, the third additional line 67 of the second switching unit 70 is connected to the first center tap 91. Depending on the design used, in particular on the required electrical power, more than one third additional line 67 may be provided in order to connect the second switching unit 70 to the second and / or third center tap 92, 93 in addition to the first center tap 91.

[0030] However, if more than one third further line 67 is provided, a blocking diode 94 must be arranged in each of the third further lines 67, as shown in dashed lines in Fig. 2, in order to achieve electrical isolation of the additional connecting lines 56, 57, 58. When using exactly one third additional line 67, the blocking diode 94 is not necessary.

[0031] The arrangement of the Fig.2 can have multiple switching states. In a first switching state, in which a DC voltage high enough to charge the battery is present at the second terminal 5, the first and second connecting lines 51, 52 are connected to the first and second battery lines 61, 62 via the first additional switch 15 and the second additional switch 16 and the first and second additional lines 65, 66, respectively, and the battery 3 is thus charged. The voltage at the second terminal 5 is detected by means of a sensor unit 55 and reported to the charging management system 40. The charging management system 40 is connected to the second switching unit 70 and the switches of the second switching unit 70 via control lines. The charging management system 40 switches the first additional switch 15, the second additional switch 16, and the first switch 13 or the second switch 14 to a closed position accordingly.In addition, the third additional switch 17 and the fourth additional switch 18 are switched to the open position or held in the open position. In addition, the first and second switches 13, 14 are switched to a closed position or held in the closed position.

[0032] If the charging management system 40 detects that a direct voltage is present at the second terminal 5, but that this voltage is lower than the nominal voltage of the battery 3, the charging management system 40 switches the second and third additional switches 16, 17 and the fourth additional switch 18 to a closed position. As a result, a negative voltage or ground is applied to the second terminal 12 of the battery 3 via the second connecting line 52. In addition, the positive voltage of the second terminal 5 is applied to the first center tap 91 via the third additional line 67. The charging management system 40 is also connected to the converter 8. In this switching position, the charging management system 40 controls the converter 8 in such a way that the direct voltage of the second terminal 5 is increased to the required higher nominal voltage of the battery 3 and is fed to the positive terminal 11 of the battery 3 via the first supply line 63.Thus, the converter 8, which is intended to drive the motor 9, is used as a DC-DC converter and to charge the battery 3. Depending on the selected design, the converter 8 can have a DC-DC converter, independent of the partial converters 21, 22, which is arranged between the battery 3 and the partial converters 21, 22 and adjusts the DC voltage between the battery and the converter.

[0033] A further sensor unit 23 is provided at the first terminal 4, which detects whether an alternating voltage suitable for charging the battery 3 is present at the first terminal 4. The further sensor unit 23 is connected to the charging management system 40. If the charging management system 40 detects that a corresponding alternating voltage is present at the first terminal 4, the charging management system 40 switches the first, second, third, and fourth further switches 15, 16, 17, 18 to the open position or holds them in the open position. In addition, the first and second switches 13, 14 are switched to the closed position. Furthermore, the converter 8 is controlled by the charging management system 40 in such a way that the alternating voltage of the first terminal 4 is rectified and raised to the voltage level required for charging the battery.The rectified voltage with the correspondingly high voltage level is applied via the first and two supply lines 63, 64 to the poles 11, 12 of the battery 3 to charge the battery 3.

[0034] Depending on the selected embodiment, the first and second switches 13, 14 can also be omitted and the first pole 11 of the battery 3 can always be connected to the first battery line 61 and the second pole 12 of the battery 3 can always be connected to the second battery line 62.

[0035] The converter 8 can thus be used to charge the battery 3 when an alternating voltage is applied to the first terminal 4. Charging takes place via a three-phase voltage network with a voltage of, for example, 230 to 400 V or more.

[0036] In order to be able to use the converter 8, which is provided for driving the motor 9, to charge the battery 3, measures are taken to prevent the generation of torque in the motor 9 while the battery 3 is charging. For this purpose, the coils of the electric motor 9 are each divided into the first and fourth, second and fifth, third and sixth sub-coils 81, 82, 83, 84, 85, 86, with two sub-coils connected in series. The first, second and third sub-coils 81, 82, 83 are connected to an AC voltage section of the first sub-converter 21. The fourth, fifth and sixth sub-coils 84, 85, 86 are connected to an AC voltage section of the second sub-converter 22. DC voltage sections of the sub-converters 21, 22 are connected to the first and second supply lines 63, 64, to which the battery 3 is connected. The first and second partial converters 21, 22 are controlled synchronously.

[0037] To drive the electric motor 9, the two partial converters 21, 22 are operated in push-pull mode on each of the motor phases, so that the current in the pair of series-connected partial coils flows in the same direction. This generates a rotating field that drives the motor 9 with a corresponding torque.

[0038] During charging operation, the partial converters 21, 22 in each coil can be operated in synchronism, so that the current flows in different directions in the first partial coil 81 and the fourth partial coil 84, or in the second partial coil 82 and the fifth partial coil 85, or in the third partial coil 83 and the sixth partial coil 86. The different current directions compensate for a rotating field generated in the respective partial coils, so that no motor torque is generated.

[0039] In the second charging situation, in which a charging voltage is present at the second terminal 5, which is, however, lower than the target voltage of the battery 3, the first and second partial converters 21, 22 are controlled in such a way as to convert the positive direct voltage of the second terminal 5, which is fed via the third further line 67 to the first center tap 91, via the first and fourth partial coils 81, 84 and the first and second partial converters 21, 22 into a correspondingly higher voltage, which is fed via the first supply line 63 and the first battery line 61 to the positive pole 11 of the battery 3.

[0040] In the illustrated embodiment, each sub-converter 21, 22 has three branches 71, 72, 73 arranged in parallel, with two switches 74, 75 connected in series in each branch 71, 72, 73. The ends of the branches 71, 72, 73 are each connected to the first and second supply lines 63, 64. The switches 74, 75, which are designed, for example, as transistors, are controlled by the charging management system 40 in such a way that the desired rectifier function and / or voltage converter function and / or inverter function is provided. Depending on the selected embodiment, the converter can also have other electrical and electronic components and thus be implemented in a different way.

Claims

[1] Vehicle (1) with a charging system (2) for a battery (3), with a first electrical connection (4) for an alternating voltage, wherein the first connection (4) is connected to the charging system (2), with a second electrical connection (5) for a direct voltage, wherein the second connection (5) is connected to the charging system (2), wherein the charging system (2) comprises a converter (8), wherein the converter (8) is designed to convert the alternating voltage of the first connection (4) into a direct voltage for charging the battery (3), and wherein the converter (8) is designed to convert a level of a direct voltage, which is fed from the second connection (5) to the converter (8), and to pass it on to the battery (3), wherein the converter (8) is designed to convert the direct voltage of the battery (3) into an alternating voltage for driving an electric motor (9), wherein the electric motor (9) has three strands with three coils (81, 82, 83, 84, 85,86), wherein an electrical line (51, 67) of the second terminal (5) is connected to at least one of the three coils (81, 82, 83, 84, 85, 86), wherein each coil is divided into a first and second, series-connected partial coil (81, 82, 83, 84, 85, 86), wherein a center tap (91, 92, 93) is provided between the partial coils (81, 82, 83, 84, 85, 86) of at least one coil, wherein the electrical line (51, 67) of the second terminal (5) is connected to at least one center tap (91, 92, 93). [2] Vehicle (1) according to claim 1, wherein the converter (8) comprises a DC-DC converter and an inverter, wherein the DC-DC converter is designed to be operated in two directions, wherein the inverter is designed to be operated in two directions. [3] Vehicle (1) according to claim 2, wherein the converter (8) has two partial converters (21, 22), wherein the two partial converters (21, 22) are connected in parallel and are each connected to a positive and negative supply line (61, 62) of the battery (3), wherein a first partial converter (21) is connected to an input of the three coils (81, 82, 83, 84, 85, 86), wherein the second partial converter (22) is connected to an output of the three coils (81, 82, 83, 84, 85, 86). [4] Vehicle (1) according to claim 1, 2 or 3, wherein an electrical line (51, 67) of the second terminal (5) is led to each coil (81, 82, 83, 84, 85, 86). [5] Vehicle (1) according to one of the preceding claims, wherein the second terminal (5) is connected to a switching unit (7, 70), wherein the switching unit (7, 70) is connected to the converter (8) via a third further line (67), wherein the switching unit (7, 70) is connected to battery terminals (61, 62) via further lines (65, 66), wherein a charging management system (40) is provided, wherein the charging management system (40) is designed to switch the switching unit (7, 70) depending on the electrical voltage at the second terminal (5) in such a way that the second terminal (5) is connected either to the converter (8) via the electrical line (51, 67) or to the battery terminals (61, 62) via the further lines (65, 66). [6] Vehicle (1) according to one of claims 3 to 5, wherein a partial converter (21, 22) is designed in the form of three parallel-connected branches (71, 72, 73), each with two switches (74, 75), the branches (71, 72, 73) being connected between the supply lines (63, 64). [7] Charging system (2) for a battery (3), with a first electrical connection (4) for an alternating voltage, wherein the first connection (4) is connected to the charging system (2), with a second electrical connection (5) for a direct voltage, wherein the second connection (5) is connected to the charging system (2), wherein the charging system (2) comprises a converter (8), wherein the converter (8) is designed to convert the alternating voltage of the first connection (4) into a direct voltage for charging the battery (3), and wherein the converter (8) is designed to convert a level of a direct voltage, which is fed from the second connection (5) to the converter (8), and to pass it on to the battery (3), wherein the converter (8) is designed to convert the direct voltage of the battery (3) into an alternating voltage for driving an electric motor (9), wherein the electric motor (9) has three strands with three coils (81, 82, 83, 84, 85, 86),wherein an electrical line (51, 67) of the second terminal (5) is connected to at least one of the three coils (81, 82, 83, 84, 85, 86), wherein each coil is divided into a first and second, series-connected partial coil (81, 82, 83, 84, 85, 86), wherein a center tap (91, 92, 93) is provided between the partial coils (81, 82, 83, 84, 85, 86) of at least one coil, wherein the electrical line (51, 67) of the second terminal (5) is connected to at least one center tap (91, 92, 93). [8] Charging system (2) according to claim 7, wherein the converter (8) comprises a DC-DC converter and an inverter, wherein the DC-DC converter is designed to be operated in two directions, wherein the inverter is designed to be operated in two directions. [9] Charging system (2) according to claim 8, wherein the converter (8) has two partial converters (21, 22), wherein the two partial converters (21, 22) are connected in parallel and are each connected to a positive and negative supply line (61, 62) of the battery (3), wherein a first partial converter (21) is connected to one input of the three coils (81, 82, 83, 84, 85, 86), wherein the second partial converter (22) is connected to one output of the three coils (81, 82, 83, 84, 85, 86). [10] Charging system (2) according to claim 7, 8 or 9, wherein an electrical line (51, 67) of the second terminal (5) is led to each coil (81, 82, 83, 84, 85, 86). [11] Charging system (2) according to one of claims 7 to 10, wherein the second terminal (5) is connected to a switching unit (7, 70), wherein the switching unit (7, 70) is connected to the converter (8) via a third further line (67), wherein the switching unit (7, 70) is connected to battery terminals (61, 62) via further lines (65, 66), wherein a charging management system (40) is provided, wherein the charging management system (40) is designed to switch the switching unit (7, 70) depending on the electrical voltage at the second terminal (5) in such a way that the second terminal (5) is connected either to the converter (8) via the electrical line (51, 67) or to the battery terminals (61, 62) via the further lines (65, 66). [12] Charging system (2) according to one of claims 9 to 11, wherein a partial converter (21, 22) is designed in the form of three parallel-connected branches (71, 72, 73), each with two switches (74, 75), wherein the branches (71, 72, 73) are connected between the supply lines (63, 64).

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