MAIN SWITCH OF AN ELECTRICAL SYSTEM OF A VEHICLE

Abstract

A main switch of an electrical system of a vehicle, in particular agricultural machinery, with a first main current path in which a first switch is introduced, and with a second main current path. The main switch comprises a control unit and the first main current path is associated with a first current sensor and the second main current path is associated with a second current sensor. By means of the control unit, the first switch is actuated as a function of a deviation from the electrical currents detected by the two current sensors.

Claims

1. A main switch of an electrical system of a vehicle), in particular agricultural machinery, the main switch comprising: a first main current path, in which a first switch is introduced; a second main current path; and a control unit, wherein the first main current path is associated with a first current sensor and the second main current path is associated with a second current sensor, and wherein, via the control unit, the first switch is actuated as a function of a deviation of electric currents detected by the two current sensors.

2. The main switch according to claim 1, wherein the first switch is bridged by a precharging circuit.

3. The main switch according to claim 1, further comprising a discharge circuit, which is routed against one of the main current paths.

4. The main switch according to claim 1, wherein, in the second main current path, a second switch is introduced, which is operated by means of the control unit.

5. The main switch according to claim 1, further comprising a further power port via which the control unit is energized.

6. The main switch according to claim 5, wherein, between the further power port and the control unit, a DC-DC converter is connected.

7. The main switch according to claim 1, further comprising a data interface, which is signally connected to the control unit.

8. The main switch according to claim 1, further comprising a housing within which the first switch, the control unit and the current sensors are arranged, and wherein the two main current paths extend between two ports, which are located outside the housing.

9. The main switch according to claim 8, wherein the housing comprises a box-like base body with a recess in which a plastic body is inserted, to which the ports of the first main current path and the first switch are attached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0049] FIG. 1 is schematically, a vehicle with a main switch;

[0050] FIG. 2 is a block diagram of the main switch;

[0051] FIG. 3 is in perspective, the main switch in an exploded view, which comprises two modules;

[0052] FIG. 4 is in perspective, one of the modules comprising a first switch;

[0053] FIG. 5 is the main switch, in perspective, in a rear view;

[0054] FIGS. 6, 7 are in perspective, in a front or rear view, an alternative embodiment of the main switch.

DETAILED DESCRIPTION

[0055] FIG. 1 shows a vehicle 2 in the form of an agricultural machine, namely a tractor, i.e., a traction machine, schematically simplified. The vehicle 2 comprises a plurality of wheels 4, at least some of which are driven by means of an internal combustion engine 6 via an unspecified transmission. By means of the internal combustion engine 6, a generator 8 is also driven, by means of which a vehicle electrical system 10 is supplied with electrical energy. For this purpose, an electrical DC voltage of 48 V is fed into the vehicle electrical system 10 by means of the generator 8. The vehicle electrical system 10 comprises a main switch 12, which is connected directly downstream of the generator 8. In other words, between the generator 8 and the main switch 12, with the exception of a connecting line 13, no other components of the vehicle electrical system 10 are arranged. Also, no other components are contacted there with the vehicle electrical system 10.

[0056] The vehicle 2 further comprises a battery 14, by means of which a secondary electrical system 16 is supplied. By means of the battery 14, an electrical DC voltage of 12 V is provided, which is thus routed by means of the secondary vehicle electrical system 16. The battery 14 is charged on demand when operated by means of the generator 8 via an unspecified DC-DC converter. With the secondary vehicle electrical system 16, the main switch 12 and an on-board computer 18 are energized. The on-board computer 18 and the main switch 12 are signally connected by means of a bus system 20, so that it is possible to exchange data / signals between the on-board computer 18 and the main switch 12.

[0057] A trailer 22 is coupled to the vehicle 2 and detachably connected to it. The trailer 22 carries an auxiliary unit 24, which is energized by means of the vehicle electrical system 10. For this purpose, the auxiliary unit 24 has an unspecified plug, which is electrically connected to a line 26 of the vehicle electrical system 10 downstream of the main switch 12. By means of the auxiliary unit 24, a certain function is performed during operation. For example, the trailer 22 is a planting machine, and by means of the auxiliary unit 24, seedlings are placed in suitably positioned guides.

[0058] FIG. 2 shows a schematically simplified circuit diagram of the main switch 12. The main switch 12 comprises a housing 28 through which a first main current path 30 and a second main current path 32 extend. Each main current path 30, 32 is associated with two ports 33, which are arranged outside the housing 28 and between which the main current paths 30, 32 extend. In this case, each main current path 30, 32 or each port 33 is routed through corresponding openings of the housing 28.

[0059] One of the ports 33 of the first main current path 30 and one of the ports 33 of the second main current path 32 are directly connected to the connecting line 13 leading to the generator 8. The remaining ports 33, however, are electrically contacted with the line 26, which is thus connected to them.

[0060] In the first main current path 30, a first switch 34 is introduced, which is designed as a relay. In this case, it is possible to carry and to switch an electric current of 250 A by means of the first switch 34, wherein an electrical voltage applied to the first switch 34 may be 48 V. By means of the first switch 34, it is possible to interrupt a current flow via the first main current path 30, namely by opening the first switch 34. When the first switch 34 is closed, on the other hand, a current flows via the first main current path 30. The first switch 34 is bridged with a pre-charging circuit 36, which comprises an unspecified further switch, which is preferably a relay or alternatively a semiconductor switch, and which is connected in series with a resistor.

[0061] The first switch 34 and the pre-charging circuit 36, i.e., the further switch, are operated by means of a control unit 38 and consequently actuated. In this case, the electrical energy required for switching the first switch 34 and the further switch 36 is provided by means of the control unit 38 during operation and a corresponding switching voltage is applied to the respective switches for this purpose.

[0062] In the second main current path 32, a second switch 40, which is structurally identical to the first switch 34, is introduced in at least some embodiments of the invention. The second switch 40, if present, is also actuated by means of the control unit 38. Thus, it is possible by means of the second switch 40 to also separate the second main current path 32, so that a current flow over this is interrupted. The main current path 32 is electrically guided to ground in an unspecified manner.

[0063] With the control unit 38, further a first current sensor 42 and a second current sensor 44 are operated, which are identical to each other and each designed as a shunt. Herein, the first current sensor 42 is associated with the first main current path 30, and the second current sensor 44 is associated with the second main current path 32. During operation, measurement data are generated by means of the two current sensors 42, 44, which are read out by means of the control unit 38. In this case, the electric current conducted with each of the main current paths 30, 32 is detected by means of the two current sensors 42, 44 and the control unit 38. If a deviation between the electrical currents detected by the two current sensors 42, 44 is greater than a limit value of 0.5 A, the first switch 34 is opened so that a current flow over the first main current path 30 is prevented. Such a difference occurs, for example, if there is a ground fault of the line 26 or a malfunction of the auxiliary unit 24, which leads to leakage currents. In this case, further damage to the auxiliary unit 24 or the environment of the vehicle 2 and the trailer 22 is thus avoided by actuating the first switch 34. In addition to the first switch 34, the second switch 40 is also actuated so that there is no electrical voltage present at all on the line 26. In an unspecified variant, the two current sensors 42.44 are realized by means of a common unit, namely as a residual current sensor.

[0064] If the auxiliary unit 24 is to be operated, the second switch 40 is first closed. Before the first switch 34 is transferred to the electrically conductive state, the pre-charging circuit 36 is first actuated, namely the further switch. Thus, an electric current flows first via the pre-charging circuit 36, which is limited due to the resistance of the pre-charging circuit 36. The electrical voltage applied to the terminals 33 facing the line 26 is also limited, so that current peaks in the vehicle electrical system 10 are avoided. Only when the electrical voltage generated via the first switch 34 falls below a certain limit is the first switch 34 closed and then the further switch is opened, so that the pre-charging circuit 36 is no longer current bearing. Thus, no electrical losses occur in the pre-charging circuit 36, and the electrical resistance of the first main current path 30 is comparatively low.

[0065] To determine the electrical voltage applied via the first switch 34, the main switch 12 comprises a first voltage sensor 46 and a second voltage sensor 48, by means of which the electrical voltage applied between the two main current paths 30, 32 can be measured. Between the two voltage sensors 46, 48 are the first switch 34 and the second switch 40. The two voltage sensors 46, 48 are signally connected to the control unit 38.

[0066] In addition to determining the applied electrical voltage via the first switch 34, the first switch 34, and optionally the second switch 40, is actuated on the basis of the respective electrical voltage detected by means of the voltage sensors 46, 48 and the control unit 38. If, for example, the electrical voltage detected by the second voltage sensor 48 decreases, which is the case with a short circuit of the auxiliary unit 24, the first switch 34 and the second switch 40 are also actuated, which prevents a further malfunction.

[0067] The main switch 12 further comprises a discharge circuit 50, which is routed on the side of the first switch 34 facing the line 26 against the first main current path 30. The discharge circuit 50 has a resistor and a further switch, which are electrically connected in series. The remaining end of the discharge circuit 50 is electrically guided to ground. In an unspecified variant, the discharge circuit 50 is connected between the two main current paths 30, 32, wherein the discharge circuit 50 is located on the side of the first switch 34 and the second switch 40 facing away from the generator 8. If there is a malfunction, for example due to too large a deviation of the detected electrical currents or a certain applied electrical voltage, or if a certain condition is present, so that the first switch 34 and the second switch 40 are opened, the discharge circuit 50 is actuated. In this case, the further switch is closed so that the first main current path 30 is electrically guided to ground. Thus, after opening the first switch 34, ground is present at the auxiliary unit 24 as an electrical potential, which is why a safe separation of the trailer 22 is possible and troubleshooting is facilitated.

[0068] The main switch 12 further comprises a data interface 52 comprising a USB port 54, an analog port 56, and a digital port 58. The bus system 20 is connected to the digital port 58. During operation, state data are provided by means of the control unit 38 via the data interface 52, so that, for example, from the on-board computer 18, the current state of the two switches 34, 40 can be retrieved. Also, via the data interface 52, the data acquired by means of the sensors 42, 44, 46, 48 are provided, so that they can be stored, for example, on a drive connected to the USB port 54. In addition, it is possible to forward commands to the control unit 38 via the data interface 52, as a function of which the switches 34, 40 are opened or closed. Thus, it is possible to influence the current supply of the auxiliary unit 24 by means of the on-board computer 18.

[0069] The control unit 38 is energized via a further power port 60, which is electrically contacted with the secondary vehicle electrical system 16. Here, a DC-DC converter 62 is connected between the further power port 60 and the control unit 38. By means of the DC-DC converter 62, the electrical DC voltage provided at the further power port 60 is reduced from 12 V to an electrical DC voltage of 5 V. Due to the current supply via the secondary vehicle electrical system 16, the required dielectric strength of the DC-DC converter 62 is reduced.

[0070] The DC-DC converter 62 is connected to an ignition of the vehicle 2 via a further port 63. In other words, the further port 63 corresponds to the terminal 15. In this case, the DC-DC converter 62 is operated only if there is a level at the further port 63. Thus, the electrical voltage is provided by means of the DC-DC converter 62 only when the ignition is switched on, and only then is the control unit 38 operated. Thus, the energy requirement is reduced.

[0071] The first switch 34 and also the second switch 40 are designed in such a way that these are in the electrically conductive state only when a corresponding signal is applied by means of the control unit 38. In other words, the switches 34, 40 are monostable. Unless such a signal is created with the control unit 38 / such an electrical voltage is applied, the first switch 34 and the second switch 40 are in the open state. Thus, in the event of a failure of the control unit 38, or even if the ignition is switched off, operation of the components connected to the line 26, such as the auxiliary unit 24, is not possible, which increases safety.

[0072] The main switch 12 further comprises an interlock system 64, which is at least partially operated with the control unit 38. The interlock system 64 comprises a plurality of unspecified auxiliary ports, which are electrically connected to corresponding auxiliary mating plugs of the line 26. The electrical currents conducted with the auxiliary ports / auxiliary mating plugs amount to a few milliamperes, wherein the applied electrical voltage is below 50 V. When detaching the line 26 from the main switch 12, first the auxiliary ports are disconnected from the auxiliary mating plugs due to the geometric design, wherein the ports 33 are still electrically connected to the assigned mating plugs of the line 26. If the detachment of the auxiliary ports from the auxiliary mating plugs is detected, the first switch 34 and the second switch 40 are opened, so that electrical voltage is no longer present at the ports 33, which are assigned to the line 26. If, therefore, the line 26 is subsequently completely detached, there is no danger when a person touches the main switch 12 or components of the vehicle electrical system 10 connected downstream.

[0073] FIG. 3 shows a first embodiment of the main switch 12 in a perspective exploded view. The housing 28 has a box-like base body 66 which is made of an aluminum, and which is shown in FIG. 4 in perspective from the back. At the bottom of the box or pot-like base body 66, several cooling fins 67 are formed on the outside, so that the base body 66 is partially designed in the manner of a heat sink.

[0074] The base body 66 is sealed fluid-tight in the assembled state by means of a flat lid 68, also made of aluminum, wherein between these there is an unspecified seal. In an unspecified variant, the sealing effect is realized by means of an adhesive. Within the base body 66, the control unit 38 is arranged, which is attached to a circuit board or comprises this. Also attached to the circuit board are the pre-charging circuit 36 and the discharge circuit 50 and the sensors 42, 44, 46, 48 as well as other components of the main switch 12 arranged within the housing 28.

[0075] On the outside of the base body 66, outwardly facing tabs 70 are formed, which serve to attach the main switch 12 to other components of the vehicle 2. For this purpose, the tabs 70 each have an opening 72, within which corresponding mounting screws are arranged in the assembled state. In addition, the opening 70 is lined by means of an unspecified compression force limiter, which is provided by means of a metal sleeve.

[0076] On opposite (edge) sides, the base body 66 has open recesses 74 on each edge side, which are completely filled by means of a respective plastic body 76. Each plastic body 76 is a component of one of two identical modules 78, one of which is shown enlarged in perspective in FIG. 5. Here, by means of one of the modules 78, the first switch 34 is provided, and by means of the remaining one, the second switch 40. On the plastic body 76 of the respective module 78, the first or second switch 34, 40 is attached, wherein the switches 34, 40 are located on the side of the plastic body 76 facing the inside of the housing. On the opposite side of the plastic body 76, the ports 33 assigned to the respective switch 34, 40 are attached to it, which merge into a respective busbar 80 of the respective main current path 30, 32. Between the two ports 33, a platelet-shaped insulating body 82 of the plastic body 76 is arranged, which is why an unintentional short circuit between the two ports 33 is avoided when connected to other components.

[0077] The busbars 80 are overmolded with the plastic of the plastic body 76, so that the module 78 is designed fluid tight. In an unspecified variant, the busbars 80 are additionally encapsulated with a sealant. With the busbars protruding through the plastic body 76, the respective switch 34, 40 is electrically contacted. Each port 33 is formed by means of a flat conductor, which is one-piece with the respective busbar 80, and into which a bolt 84 is pressed, to which a cable lug 86 of the connecting line 13 or the line 26 can be connected.

[0078] A plug 88 is attached to the base body 66, which is partially made of a plastic. In the plug 88, the data interface 52, the further power port 60 and the further port 63 are integrated. Thus, assembly of the main switch 12 is simplified.

[0079] FIG. 6 shows an alternative embodiment of the main switch 12 in a front view and FIG. 7 in a rear view. Here, too, the main switch 12 comprises the housing 28 having the box-like or shell-like base body 66, which is closed with the lid 68, but which is not shown in FIG. 7. The box-like base body 66 is made of a plastic in this embodiment, as well as the lid not shown in more detail.

[0080] The box-like base body 66 has a rectangular cutout 90 at its bottom, in which a heat sink 92 made of an aluminum is inserted. During production, the heat sink 92 is overmolded circumferentially by means of the plastic of the base body 66, so that a fluid tight connection is created between them. In a further alternative, the heat sink 92 is tightly joined with the base body 66 using a seal and / or bond. The heat sink 92 is thermally connected via an electrically insulating thermal bridge 94 and optionally a thermal paste with components arranged in the base body 66, so that during operation a heat dissipation of these takes place. Also in this variant, the tabs 70 are formed on the base body 66 with the openings 72, within each of which one of the compression force limiters is arranged.

[0081] In this embodiment, the modules 78 are not present, but instead the similarly designed ports 33, which are arranged parallel to each other, reach directly into the base body 66 and have also been overmolded with the plastic of the base body 66 during production, so that a fluid tight connection takes place. In an unspecified variant, the sealant is additionally present, by means of which the ports 33 are potted. The ports 33 assigned to the second main current path 32 are directly electrically contacted with each other by means of one of the busbars 80, so that only a single-pole disconnection is possible in this embodiment. In other words, the second switch 40 is not present.

[0082] The remaining ports 33, in this embodiment the outer ones, are connected to each other by means of corresponding busbars 80 via the first switch 34, which is operated by means of the control unit 38 not shown herein. Here, too, the plug 88 is present, which, however, is partially formed by means of the base body 66. In this case, the plug 88 is located at the bottom of the base body 66, and by means of the plug 88, both the data interface 52, the further power port 60 and the further port 63 are provided. In addition, a further plug 90 is available, which is also inserted into the bottom of the base body 66, and into which other components can be plugged if necessary, such as a capacitor. Due to the external connection of the capacitor, replacement, for example in the event of damage, is facilitated.

[0083] The invention is not limited to the embodiments described above. Rather, other variants of the invention can be derived therefrom by the skilled person without departing from the subject-matter of the invention. In particular, all the individual features described in connection with the individual embodiments can also be combined in other ways without departing from the subject-matter of the invention.

[0084] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications as would be obvious to one skilled in the art to be included within the scope of the following claims.