Brake system with at least two energy sources

Abstract

The invention relates to a braking system (100) having at least two energy sources (116, 118) and having at least two electromechanical wheel brakes (108, 110, 112, 114), wherein a first wheel brake (108) is directly connected only to a first energy source (118) of the energy sources and is not directly connected to a second energy source (116) of the energy sources, and a second wheel brake (110) is directly connected to the second energy source (116) and is not directly connected to the first energy source (118). According to the invention, it is provided here that the wheel brakes (108, 110, 112, 114) are each configured to supply energy from a remaining energy source (116, 118) to the other wheel brakes (108, 110, 112, 114) in the event of failure of the energy source (116, 118) of the respective other wheel brakes (108, 110, 112, 114).

Description

Technical Field

[0001] The present invention relates to a braking system. Background Art

[0002] It is known from the prior art that there is a braking system having at least two energy sources and at least two, in particular four, electromechanical wheel brakes, wherein the electromechanical wheel brakes are in each case only directly connected to one of the energy sources and not to both energy sources. Such a braking system is schematically shown by way of example in Figure 1 herein.

[0003] Here, Figure 1 the braking system 100 shown herein has a pedal actuation unit 102, which consists essentially of a pedal feel simulator and is only used to determine a corresponding actuation signal in the case of actuation by the vehicle driver. The braking system 100 also has two electronic control units 104 and 106, which are connected to the pedal actuation unit 102 and are configured to generate control commands suitable for activating the wheel brakes 108, 110, 112 and 114 based on the actuation signal received from the pedal actuation unit 102. In order to transmit such control commands to the wheel brakes 108, 110, 112 and 114, the electronic control units 104 and 106 are connected to the wheel brakes 108, 110, 112 and 114 via respective cable connections. Here, in each case, two wheel brakes are connected to a single electronic control unit, thereby forming two independently controlled braking circuits. In the example shown, by way of example, the electronic control unit 104 is connected to the left front wheel brake 108 and the right rear wheel brake 114, while the electronic control unit 106 is connected to the right front wheel brake 110 and the left rear wheel brake 112.

[0004] To supply energy to the electronic control units 104 and 106 and to both the wheel brakes 108, 110, 112, and 114, the braking system 100 has two energy sources 116 and 118, for example in the form of respective batteries. However, such energy sources can equally well be interpreted as representing the vehicle's on-board electrical system. Here, the first battery 116 is connected directly specifically to the electronic control unit 106 and to the right front wheel brake 110 and the left rear wheel brake 112. The second battery 118 is in turn connected directly to the electronic control unit 104 and to the left front wheel brake 108 and the right rear wheel brake 114. For example, the right rear wheel brake 114 is not directly connected to the first battery 116. Here, the wheel brakes 108, 110, 112, and 114 are each configured as electromechanical wheel brakes and in each case have an independent control unit 120, 122, 124, and 126, which control units regulate the behavior of the respective wheel brakes based on received control commands.

[0005] Accordingly, there are two independent braking circuits, which in each case include an energy source, an electronic control unit, and two wheel brakes, which two wheel brakes are diagonally distributed in this case.

[0006] For highly automated driving in such a brake-by-wire braking system, it is necessary here that braking controlled by the driver remains possible in the case of any form of failure. This also applies in particular to faults in the electronic equipment, especially with regard to the energy supply via the energy sources. A prerequisite for this is a redundant concept for the energy supply in the vehicle, in which case a connection of the two on-board electrical systems of the vehicle must be avoided fundamentally. Otherwise, there would be a risk that in the case of a short circuit, the two on-board electrical systems would be disabled simultaneously. Braking would no longer be possible.

[0007] This basic concept is implemented in Figure 1 the shown braking system 100 by separate braking circuits, which separate braking circuits have their independent energy supply and control. Thus, in the case of a failure of one of the energy sources or one of the electronic control units in the energy source, there is always another braking circuit with two wheel brakes available, via which the braking demand can be met. However, if the effective braking system is reduced to only two operating wheel brakes, the available deceleration performance will in some cases be reduced to such an extent that the necessary safety requirements are no longer met.

[0008] Therefore, the concept that is needed is that even in the case of a failure of one of the energy sources or one of the electronic control units in the energy source, a sufficiently high deceleration performance remains available, thus ensuring safe deceleration of the vehicle. Summary of the Invention

[0009] This object is achieved by means of a braking system as described below.

[0010] In the case of a braking system having at least two energy sources and at least two electromechanical wheel brakes, wherein a first wheel brake is specifically directly connected to a first energy source of the energy sources and not directly connected to a second energy source of the energy sources, and a second wheel brake is directly connected to the second energy source and not directly connected to the first energy source, it is provided according to the invention that the wheel brakes are respectively configured to supply energy from the remaining energy source to the other wheel brakes in the event of a failure of the energy source of the respective other wheel brake.

[0011] Here, the "direct connection" between the wheel brake and the energy source is understood to mean a connection without other components or devices being connected between the wheel brake and the energy source. Thus, if at least one device (e.g., another wheel brake) is only provided in the connection between the considered wheel brake and the associated energy source, there is no longer a "direct connection" in the context of the present invention. Here, the "energy source" can be understood to mean, for example, a battery or the vehicle's on-board electrical system.

[0012] By means of the described configuration of the braking system, the failure of one of the energy sources can be compensated for by the wheel brake directly affected by the failure still continuing to supply energy from the remaining energy source that is still retained, such that at least the deceleration performance of the wheel brakes connected to the unaffected wheel brakes is maintained. Here, the energy transfer between the wheel brakes is preferably controlled by the control unit of the wheel brakes. Here, the control unit of the wheel brake can also be specifically configured to output a corresponding alarm message if a failure of the energy source is recognized, and this alarm message indicates to the vehicle driver, for example, visually or audibly that a malfunction of the braking system has occurred.

[0013] To ensure reliable energy transfer between the wheel brakes, in one embodiment it is provided that power regulation units are respectively provided in the wheel brakes, and the power regulation units are configured to control the energy transfer from the remaining energy source to the respective other wheel brakes in the event of a failure of the energy source not connected to the wheel brake. Here, the power regulation unit can be specifically configured as part of the control unit of the wheel brake and is particularly used to isolate the corresponding wheel brake from the failed energy source in the event of a recognized failure of the wheel brake, such that, for example, a short circuit occurring due to a defect does not have any adverse effects on the other wheel brakes. It is provided here that the power regulation unit is formed in the control unit only in the case where the control unit is connected to another control unit of another wheel brake for energy transfer.

[0014] According to another embodiment, the wheel brakes affected by the failure of the energy source are supplied with energy by the unaffected wheel brakes in as efficient a manner as possible, since the first wheel brake and the second wheel brake are directly connected to each other via at least one connection line for transmitting energy from the respective energy source. Here, preferably, the connection line is charged only when one of the energy sources has failed. In addition, it can be provided here that the power regulation unit and / or the control unit of the wheel brake periodically checks the availability of the direct connection line and, if necessary, issues an alarm when it is no longer available.

[0015] Here, according to another embodiment, the safety of this arrangement can be further improved by directly connecting the first wheel brake and the second wheel brake to each other via two connection lines for transmitting energy from the respective energy source, wherein the first connection line in the connection lines is configured to specifically transmit energy from the first wheel brake to the second wheel brake, and wherein the second connection line in the connection lines is configured to specifically transmit energy from the second wheel brake to the first wheel brake. Accordingly, the connection lines respectively constitute one-way connectors, and these one-way connectors respectively only allow energy transmission in a single direction. In this way, the energy transmission paths do not affect each other, thereby improving safety.

[0016] According to another embodiment, it is further provided that the wheel brakes respectively have a first interface for connecting to the respective energy source and a second interface for connecting to the respective other wheel brakes. Here, the interfaces can in particular each be formed as part of the control unit of the wheel brake. Here, these interfaces are preferably configured such that they do not affect each other, in particular as separate plug connectors. Here, the interfaces are preferably configured such that the existing connections to the energy source or to the respective other wheel brakes can be cut off in a targeted manner. Thus, especially in the case of a defect in the energy supply or in the other wheel brakes, it is possible to prevent the defect from having a direct impact on the wheel brake under consideration. For example, in the case of a fault, a defect in the respective other wheel brake or the energy source may also cause the failure of the wheel brake under consideration as a consequential fault.

[0017] According to another embodiment, in order to improve the electrical isolation between the wheel brake and the energy source as well as between the wheel brakes themselves, it is provided that the wheel brakes are respectively connected to the energy source and / or the respective other wheel brakes via DC converters of the respective interfaces. Therefore, preferably, DC converters are respectively provided at the interfaces between the energy source and the wheel brake and between the wheel brakes.

[0018] Furthermore, according to another embodiment, a reliable and targeted connection and disconnection between the wheel brake and the energy source can be achieved by detachably connecting the wheel brake to the energy source via a switching device with an interface to the energy source and / or to the respective other wheel brakes. Thus, for example, the connection between the wheel brake and a faulty energy source can be cut off in a targeted manner via the interface, so that the rest of the braking system is not affected by the faulty energy source. Here, the switching device can be controlled by the power regulation unit or the control unit of the wheel brake. Here, the switching device can be specifically configured as a safety switch.

[0019] In particular, it can also be provided that the interface between the wheel brake and the energy source has a switching device, while the interface to the respective other wheel brakes has a DC converter, or vice versa.

[0020] According to another embodiment, furthermore, it is provided that the braking system has two brake circuits, each brake circuit having at least two wheel brakes respectively, wherein at least one wheel brake of the first brake circuit in the brake circuit is directly connected to at least one wheel brake of the second brake circuit in the brake circuit for supplying energy in the event of failure of one of the energy sources. Here, taking a vehicle with two axles as an example, it can be specifically provided that there is a direct connection between the wheel brakes of the front axle of the vehicle, between the wheel brakes of the rear axle of the vehicle, between the wheel brakes on one side of the vehicle in each case, or between the diagonally opposite wheel brakes of the vehicle.

[0021] According to another embodiment, in the above configuration with two brake circuits, it is provided that the brake circuits each have a central control unit for providing control information to the wheel brakes, wherein at least one of the wheel brakes in one brake circuit is configured to receive and process control information from the wheel brakes of the other brake circuit in the event of failure of the central control unit of the brake circuit. For this purpose, a separate bus system can be configured between the control units of the wheel brakes, and the separate bus system is separate from the direct connection of the wheel brakes for energy exchange. In this way, even in the event of failure of one of the central control units in the brake circuits, the braking adjustment function depending on the corresponding control signals of the central control unit, such as the ABS adjustment operation, can continue to be executed.

[0022] According to another embodiment, the operational reliability of the energy transfer between the wheel brakes can be improved because the braking system has at least one energy transfer unit which is directly connected to the first wheel brake and the second wheel brake respectively, and is configured to control the energy supply from the energy source of the respective other wheel brake to the affected wheel brake in the event of a failure of one of the energy sources in the energy source. Accordingly, the energy transfer unit is preferably arranged in the direct connection between the wheel brakes. By using a separate unit to control the energy transfer between the wheel brakes, the power regulation unit in the wheel brakes (the power regulation unit can essentially provide for controlling the energy transfer between the wheel brakes) can be made simpler or even completely omitted. Here, the voltage for the operation of the energy transfer unit is preferably supplied to the energy transfer unit only by the wheel brakes, such that it is not necessary to directly connect the energy transfer unit to one of the on-vehicle electrical systems in the vehicle's on-vehicle electrical system. Here, the energy transfer unit is preferably configured such that as long as one of the energy sources has not failed, the energy transfer unit remains in an energy-saving standby state. The energy transfer unit is preferably also configured such that even in the case where both energy sources are under-voltage, the energy transfer unit remains in the standby state, so as not to impose an additional burden on the on-vehicle electrical system.

[0023] Here, according to another embodiment, it is provided that the energy transfer unit is connected to the first wheel brake via a first interface and to the second wheel brake via a second interface, wherein the energy transfer unit is configured to identify a voltage drop at one of the interfaces and, in response to the identified voltage drop, maintain the voltage at the corresponding interface at least at a minimum voltage.

[0024] Here, the energy transfer unit is preferably configured such that the control of the voltage present at the interface by the energy transfer unit is performed only based on the voltage provided by the wheel brake at the interface. Preferably, no further control signal is required. For this purpose, for example, pulse width modulation generators (PWM) can be used, by means of which, within the energy transfer unit, the voltage provided at the interface is regulated only based on the voltage present at the interface and the current intensity derived from the voltage.

[0025] According to another embodiment, the safety of the braking system is improved here because the first interface and the second interface are spatially separated such that the interfaces do not affect each other, especially in the case where one of the interfaces is defective, especially in the case of uncontrollable mechanical damage. In particular, the two interfaces can be spatially separated plug connectors. The defect or mechanical damage here particularly refers to malfunctions that cause undesired electrical contact to occur between essentially separated contact parts. For example, such behavior may occur due to the melting or burning of one of the contact parts.

[0026] In addition to the connectors of the energy transfer unit for supplying voltage to or from the wheel brakes, the energy transfer unit preferably also has two ground connectors, which can coincide with the corresponding plug connectors to the wheel brakes.

[0027] According to another embodiment, it is also provided that the energy transfer unit hereby has a first circuit for supplying voltage at a first interface and a second circuit for supplying voltage at a second interface, wherein the first circuit is galvanically isolated from the second circuit. In this way, it can be avoided that, for example, a short circuit of a faulty energy source affects the brake circuit not directly connected to the faulty energy source.

[0028] Here, according to another embodiment, it is provided that the circuits hereby supply voltage from the respective other circuit in the event of a failure of one of the energy sources in the energy source. For this purpose, in particular in the energy transfer unit, a transformer can be provided, which preferably has a ferrite core, through which the voltage present at the first interface and thus in the first circuit can be transferred to the second circuit. The voltage provided at the interface of the second circuit based on the voltage thus provided can then preferably be controlled, based on the voltage and current present in the circuit, by means of the PWM generator of the energy transfer unit, which is provided in the second circuit.

[0029] According to another embodiment, in order to avoid an overload of one of the energy sources in the event of a failure of the other energy source, it is provided that the energy transfer unit hereby is configured to supply energy with a maximum defined power to the wheel brakes affected by the failure in the event of a failure of one of the energy sources in the energy source. The limitation is preferably achieved by means of a correspondingly configured PWM generator of the energy transfer unit. Here, the power transmitted is preferably regulated based on the respective current, which simplifies the measurement of the power transmitted. Description of the Drawings

[0030] The preferred embodiments of the present invention will be explained in more detail below based on the drawings. In the drawings:

[0031] Figure 1 A schematic illustration of a conventional braking system is shown,

[0032] Figure 2 A schematic illustration of an exemplary braking system with four wheel brakes is shown, two of which are connected to each other to supply energy to each other,

[0033] Figure 3 A schematic illustration of an exemplary connection configuration of an energy source and a control unit of a wheel brake is shown,

[0034] Figure 4 Schematic illustration showing an additional exemplary connection configuration of an energy source and a control unit of a wheel brake,

[0035] Figure 5 Schematic illustration showing an exemplary connection configuration of an energy source, a control unit, and an energy transmission unit of a wheel brake,

[0036] Figure 6 Schematic illustration of a circuit of an exemplary energy transmission unit, and

[0037] Figure 7 Schematic circuit diagram showing the arrangement of an energy source, a control unit, and an energy transmission unit of a wheel brake.

[0038] Hereinafter, similar or identical features are denoted by the same reference numerals. DETAILED DESCRIPTION

[0039] Figure 2 Schematic illustration of a brake system 100 is shown, which largely corresponds to the brake system 100 described above with respect to Figure 1 However, for clarity, the pedal actuation unit 102, the electronic control units 104 and 106, and the wheels disposed at the wheel brakes 108, 110, 112, and 114 are not shown in Figure 2 herein.

[0040] As compared with the brake system 100 shown in Figure 1 in the brake system 100 of Figure 2 it is provided that the left front wheel brake 108 and the right front wheel brake 110 are connected to each other via a connection line 128 such that in the event of a failure of one of the energy sources 116 or 118, the wheel brake not affected by the failure can supply energy to the corresponding affected wheel brake.

[0041] To control the energy transfer in the event of a failure of one of the energy sources 116 or 118, power regulation units 130 and 132 are respectively formed in each of the control unit 120 of the wheel brake 108 and the control unit 122 of the wheel brake 110. Here, the power regulation units 130 and 132 are respectively preferably designed to identify a failure of one of the energy sources 116 or 118 and, in response thereto, cut off the connection between the affected wheel brake and the failed energy source and draw the energy required for the operation of the affected wheel brake from the unaffected wheel brake.

[0042] Figure 2The connection between the left front wheel brake 108 and the right front wheel brake 110 shown in [the figure] is in this case merely an example of how at least partial redundancy can be created for the case of failure of one of the energy sources 116 or 118. For example, in the case of failure of the energy source 116 and thus the energy supply to the wheel brake 110, the remaining available braking performance of the braking system 110 will be significantly increased by means of the wheel brake 108 compared to the braking performance available in the case of failure of both wheel brakes 112 and 110, since three quarters of the wheel brakes can continue to operate.

[0043] However, in the context of the present invention, it is also possible in any case to connect the left rear brake 112 to the right rear brake 114 via a corresponding connecting line for energy exchange. It is also possible to connect the wheel brakes on one side, that is to say, to connect the wheel brake 108 to the wheel brake 112, or the wheel brake 110 to the wheel brake 114 for energy exchange. In addition, it is also possible in each case to connect more than two wheel brakes to each other for energy exchange. For example, correspondingly, in addition to the connection between the left front wheel brake 108 and the right front wheel brake 110, a further connection can also be provided between the left rear wheel brake 112 and the right rear wheel brake 114. However, in the described concept, the variant in which the front wheel brakes 108 and 110 can compensate for the failure of the correspondingly associated energy sources 116 and 118 is particularly advantageous, since it is usually the case that during vehicle deceleration most of the deceleration performance is provided by the wheel brakes of the front axle.

[0044] Below, different exemplary variants of the connection configuration of the energy sources and control units of the wheel brakes will now be described with reference to Figure 3 and Figure 4 the corresponding schematic illustrations. Here, purely by way of example, it is assumed that the control unit shown on the left side is the control unit 120 of the left front wheel brake 108, and the control unit shown on the right side is the control unit 122 of the right front wheel brake 110. The two energy sources 116 and 118 shown can be, for example, batteries or the vehicle on-board electrical system of a vehicle using the braking system 100 described above.

[0045] Here, the control units 120 and 122 have substantially the same construction and each control unit respectively includes microcontrollers 134 and 136, which are configured, for example, to enable the wheel brakes 108 in order to achieve the braking requirement. In addition, the control units 120 and 122 each respectively have power regulation units 130 and 132, which are configured to control the energy supply of the wheel brakes not affected by the failure in the event of a failure of the energy source associated with the wheel brakes. For this purpose, the power regulation unit 130 of the control unit 120 is connected, for example, to the energy source 118 via the first interface 138, while the connection to the control unit 122 of the right front wheel brake 110 is realized via the second interface 140.

[0046] Similarly, the control unit 122 of the right front wheel brake 110 also has a first interface 142 for connection to the energy source 116 and a second interface 144 for connection to the control unit 120. In addition, the two control units 120 and 122 each have a data bus 146 and 148 in each case, via which control information for enabling the wheel brakes can be exchanged, for example.

[0047] In Figure 3 In the variant shown in a) of, the switch units configured as safety switches are respectively provided at the first interfaces 138 and 142 of the control units 120 and 122, so that in the event of a failure of one of the energy sources, the connection between the control units 120, 122 and the correspondingly associated energy sources 116 and 118 can be cut off. The second interfaces 140 and 144 of the control units 120 and 122 each have a DC converter, by means of which the current isolation of the control units 120 and 122 is realized.

[0048] During the normal operation of the shown braking system 100, that is, during the normal operation of the energy sources 116 and 118, the safety switches of the interfaces 138 and 142 are closed, so that the control units 120 and 122 are supplied with energy from the correspondingly associated energy sources 116 and 118 in each case. Here, no energy is transmitted via the connection line 128. The control units 120 and 122 or the associated power regulation units 130 and 132 can be configured in this case to periodically check the availability of the connection line 128 and, if necessary, output a fault message in the event of the non-operation of the connection line 128.

[0049] For example, if the energy source 116 fails due to a short circuit or some other defect now, this is recognized by the power conditioning unit 132, and the safety switches of the interfaces 142 are opened. The energy required to operate the wheel brakes 110 is drawn from the wheel brakes 108 via the connecting line 128, or directly from the energy source 118. Here, the regulation of the energy transfer by the power conditioning units 130 and 132 is preferably configured such that an uninterrupted transfer of energy to the energy supply via the wheel brakes 108 is ensured. At the same time, overload protection can also be achieved by means of the described infrastructure. For example, if a short circuit occurs at the connecting line 128, this can also be recognized based on the overload detection of the power conditioning units 130 and 132, such that the DC converters of the interfaces 140 and 144 are deactivated in order to avoid the impact of the recognized short circuit on the control units 120 and 122.

[0050] In Figure 3 In the variant shown in b) of , the safety switches of the first interfaces 138 and 142 of the control units 120 and 122 are replaced by DC converters. In the event of a fault, the use of DC converters at the two interfaces further reduces the possibility of current coupling between the control unit 120 and the energy source 118, or between the control unit 122 and the energy source 116, respectively.

[0051] In contrast, in Figure 4 In the variant shown in a) of , the first interfaces 138 and 142 and the second interfaces 140 and 144 of the control units 120 and 122 are each equipped with safety switches, where the safety switches can preferably be actuated by the power conditioning units 130 and 132. The shown embodiment has a significant cost advantage over the use of DC converters in the interfaces, since the production of safety switches is generally cheaper than that of voltage converters.

[0052] In Figure 4 In the variant shown in b) of , the control units 120 and 122 also each have a third interface 150 and 152 in each case, and the control units 120 and 122 are also connected to each other via the third interfaces for energy exchange. Here, in the shown embodiment, all the interfaces of the control units 120 and 122 are each equipped with safety switches, and the corresponding connecting members can be cut off by the safety switches if necessary. Here, the connecting line 128 between the second interfaces 140 and 144 in each case is configured to specifically transfer energy from the first control unit 120 to the second control unit 122, while another connecting line 154 between the third interfaces 150 and 152 in each case is configured to specifically transfer energy from the second control unit 122 to the first control unit 120. Therefore, in this variant, the connecting lines 128 and 154 are one-way connecting members in each case, such that the directional paths between the control units 120 and 122 are separate in each case.

[0053] Figure 5 shows another embodiment of a variant of the connection configuration of the control units 120 and 122 and the energy sources 116 and 118 as described above with reference to Figure 3 and Figure 4 In the variant shown here (which basically corresponds to the variant of a) of Figure 4 ), the energy transfer unit 160 is arranged in the connection line 128 between the respective second interfaces 140 and 144 of the control units 120 and 122. Here, the energy transfer unit 160 is configured to control the energy exchange between the control units 120 and 122, or between the wheel brakes 108 and 110, based on the voltages U1 and U2 provided at the interfaces 140 and 144.

[0054] Now the operation of the energy transfer unit 160 will be described below with reference to Figure 6 which shows two variants of the circuit by means of which the energy transfer unit 160 within the meaning of the present invention can be implemented. Here, the variants of the energy transfer unit shown are preferably configured as independent control units in a separate housing, where the energy transfer unit preferably has only four connectors. The connectors are here used to supply the voltages U1 and U2 from the second interfaces 140 and 144 of the control units 120 and 122 and from two independent ground connectors (GND1, GND2). Here, preferably, in each case one voltage (U1 or U2) and in each case one ground (GND1, GND2) are combined in one plug connector 166 or 168, where the two resulting plug connectors 166 and 168 and the corresponding interfaces of the energy transfer unit 160 are preferably spatially separated from each other.

[0055] In Figure 6 the variant shown in a), two separate circuits 162 and 164 are formed within the energy transfer unit 160, which circuits are in each case connected to one of the plug connectors 166 and 168, where the circuits 162 and 164 are galvanically isolated from each other. To transfer energy between the circuits 162 and 164, the energy transfer unit 160 has a transformer 170 with a ferrite core. In addition, pulse width modulation generators (PWM) 172 and 174 are arranged in each of the circuits 162 and 164, which pulse width modulation generators are each configured to transfer energy precisely to the wheel brake whose associated energy source has failed, or to the control unit of said wheel brake, in a manner depending on the voltages U1 and U2 present in the circuits 162 and 164 and the respective current intensities I1 and I2 via the respective circuits.

[0056] Capacitors 176 and 178 are connected in parallel relative to PWM generators 172 and 174 in each case, while the outputs of PWM generators 172, 174 are connected to the gate connectors of transistors 184, 186 (e.g., MOSFETs) in each case. The transistors connect the ferrite core transformer 170 to the respective grounds GND1 and GND2 via downstream elements 180 and 182 for current measurement. Furthermore, transistors 184 and 186 are connected across diodes 188 and 190 in each case, such that the switching voltage of transformer 170 is rectified and supplied to capacitors 176 and 178.

[0057] Here, due to its mirror-symmetrical design, the energy transfer unit 160 is capable of regulating the energy transfer from the control unit 120 to the control unit 122 and also the energy transfer from the control unit 122 to the control unit 120. Here, the design of the energy transfer unit has the effect of fundamentally excluding the case where both PWM generators 172 and 174 operate simultaneously. Here, the energy transfer unit 160 is preferably designed such that the control of the energy transfer unit 160 does not require an additional communication line, where the energy transfer unit 160 can more precisely control the energy transfer between the wheel brakes based only on the values U1, U2, I1, and I2.

[0058] The behavior of the energy transfer unit 160 for different input voltages U1 and U2 will be described by way of example below.

[0059] In the first case, voltages of U1 > 9V and U2 > 9V appear at the two inputs of the plug connectors 166 and 168, respectively. In this case, the PWM generators 172 and 174 are not enabled, such that no energy is transferred and only a low static current flows within the energy transfer unit 160. If the voltages U1 and U2 at both inputs are each very low, that is, if the energy sources 116 and 118 both malfunction or the associated vehicle electrical system is weak, the energy transfer unit 160 also exhibits the same behavior.

[0060] However, if a low voltage appears only at one of the voltage inputs U1 or U2 (e.g., U1 > 10V, U2 < 9V), the PWM generator 172 is configured to modulate the voltage present at the ferrite core transformer 170 such that at least 9V of voltage is maintained at the connector U2. The voltage U2 is maintained at 9V only as long as the current intensity I1 < 15A and the current intensity I2 is below 20A. This regulation is preferably limited by the currents I1 and I2. Thus, current-limited energy transfer limits the power to a range of approximately 150W to 180W. In this way, the still-operating energy source or the corresponding vehicle electrical system can be protected from overload.

[0061] For example, if the voltage U1 is lower than 9V and the voltage U2 is higher than 10V, the above behavior runs conversely.

[0062] Figure 6 b) of shows an alternative configuration of the energy transmission unit 160, where instead of a ferrite core transformer, an inductor 192 is connected in series such that there is no longer current isolation between circuits 162 and 164. Here too, in the case of a voltage drop occurring at one of the inputs U1 or U2, the energy required for the operation of the connected wheel brakes is provided by the corresponding PWM generators 172 or 174 at the relevant outputs.

[0063] Figure 7 shows a schematic circuit diagram of the arrangement of the energy sources 118 and 116, the control units 120 and 122 of the wheel brakes 108 and 110, and the energy transmission unit 160 connected between the control units 120 and 122. Here, in each of the control units in the control unit, a current limiting unit 130 and 132 are respectively provided in each case, and the current limiting unit controls the current flow between the control units 120 and 122 in the case of a failure or malfunction of the corresponding energy source 116 or 118. Here, the control units 120 and 122 are configured to exchange information items via the data bus 194, for example in order to check the reasonableness of the identified fault status and to react appropriately thereto, in particular by cutting off the connection to the energy source 116 or 118 and deactivating the energy supply of the ECU power management 132 and 132 to the energy transmission unit 160.

[0064] The described infrastructure having the energy transmission unit 160 arranged in the energy transmission path between the wheel brakes can in principle be provided in each variant of the variant of the connection between the wheel brakes as described above with reference to Figure 2 For example, in particular, it can also be provided that the energy transmission unit 160 is arranged between the wheel brakes 112 and 114 of the rear axle of the vehicle thereby, or that in each case, one energy transmission unit 160 is arranged between the wheel brakes 108 and 110 of the front axle of the vehicle and in the energy transmission path between the wheel brakes 112 and 114 of the rear axle.

Claims

1. A braking system (100) having at least two energy sources (116, 118) and having at least two electromechanical wheel brakes (108, 110, 112, 114), wherein, The first wheel brake (108) is directly connected only to the first energy source (118) among the energy sources and is not directly connected to the second energy source (116) among the energy sources. The second wheel brake (110) is directly connected to the second energy source (116) and is not directly connected to the first energy source (118). Characterized in that the wheel brakes (108, 110, 112, 114) are respectively configured to supply energy from the remaining energy source (116, 118) to other wheel brakes (108, 110, 112, 114) in the case where the energy sources (116, 118) of the corresponding other wheel brakes (108, 110, 112, 114) fail. Power adjustment units (130, 132) are respectively provided in the wheel brakes (108, 110, 112, 114). The power adjustment units are configured to control the energy transfer from the remaining energy source (116, 118) to the corresponding other wheel brakes (108 110, 112, 114) in the case where the energy sources (116, 118) not connected to the wheel brakes (108, 110, 112, 114) fail. The power adjustment units are further configured to isolate the corresponding wheel brakes from the failed energy source in the case where a wheel brake failure is recognized. The braking system (100) has at least one energy transfer unit (160). The at least one energy transfer unit is directly connected to the first wheel brake (108) and the second wheel brake (110) respectively and is configured to control the energy supply of the affected wheel brakes (108, 110, 112, 114) through the energy sources (116, 118) of the corresponding other wheel brakes (108, 110, 112, 114) in the case where one of the energy sources (116, 118) fails. The energy transfer unit (160) is connected to the first wheel brake (108) via a first plug connector (166) and is connected to the second wheel brake (110) via a second plug connector (168). Wherein, the energy transfer unit (160) is configured to identify the voltage drop at one of the first plug connector (166) and the second plug connector (168), and in response to the identified voltage drop, maintain the voltage at the corresponding plug connector (166, 168) at least at the minimum voltage.

2. The braking system (100) according to claim 1, characterized in that, The first wheel brake (108) and the second wheel brake (110) are directly connected to each other via at least one connection line (128, 154) for transferring energy from the corresponding energy sources (116, 118).

3. The braking system (100) according to claim 1 or 2, characterized in that, The first wheel brake (108) and the second wheel brake (110) are directly connected to each other via two connection lines (128, 154) for transferring energy from respective energy sources (116, 118), wherein a first connection line (128) of the connection lines is only configured to transfer energy from the first wheel brake (108) to the second wheel brake (110), and wherein a second connection line (154) of the connection lines is only configured to transfer energy from the second wheel brake (110) to the first wheel brake (108).

4. The braking system (100) according to claim 1 or 2, characterized in that, The wheel brakes (108, 110, 112, 114) each have a first interface (138, 142) for connection to a respective energy source (116, 118) and a second interface (140, 144) for connection to a respective other wheel brake (108, 110, 112, 114).

5. The braking system (100) according to claim 4, characterized in that, The wheel brakes (108, 110, 112, 114) are each connected to the energy source (116, 118) and / or to the respective other wheel brake (108, 110, 112, 114) via a DC converter of each interface (138, 140, 142, 144).

6. The braking system (100) according to claim 4, characterized in that, The respective interfaces (138, 140, 142, 144) for the energy source (116, 118) and / or the respective other wheel brake (108, 110, 112, 114) are separably connected to the wheel brake (108, 110, 112, 114) via a switching device.

7. The braking system (100) according to claim 1 or 2, characterized in that, The braking system (100) has two braking circuits, each braking circuit respectively having at least two wheel brakes (108, 110, 112, 114), wherein at least one wheel brake (108, 110, 112, 114) of the first braking circuit of the braking circuits is directly connected to at least one wheel brake (108, 110, 112, 114) of the second braking circuit of the braking circuits for supplying energy in the event of failure of one of the energy sources (116, 118).

8. The braking system (100) according to claim 7, characterized in that, The braking circuits each have a central control unit (104, 106) for providing control information to the wheel brakes (108, 110, 112, 114), wherein at least one of the wheel brakes (108, 110, 112, 114) of one braking circuit is correspondingly configured to receive and process control information from the wheel brakes (108, 110, 112, 114) of another braking circuit in the event of failure of the central control unit (104, 106) of the braking circuit.

9. The braking system (100) according to claim 1 or 2, characterized in that, The energy transfer unit (160) is configured to supply energy to the affected wheel brakes (108, 110, 112, 114) in a defined power manner in the event of failure of one of the energy sources (116, 118).

10. The braking system (100) according to claim 1 or 2, characterized in that, The first plug connector (166) is spatially separated from the second plug connector (168).

11. The braking system (100) according to claim 1 or 2, characterized in that, The energy transfer unit (160) has a first circuit (162) for providing a voltage at the first plug connector (166) and a second circuit (164) for providing a voltage at the second plug connector (168), wherein the first circuit (162) is galvanically isolated from the second circuit (164).

12. The braking system (100) according to claim 11, characterized in that, The circuits (162, 164) supply voltage from the respective other circuit (162, 164) in the event of a failure of one of the energy sources (116, 118).

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