Integration of a brake resistor into a vehicle's coolant circuit

Abstract

The present invention relates to a coolant circuit (K) of a vehicle, comprising: a cooler (1) which is designed to dissipate heat to the environment, a braking resistor (2), a first heat storage device (3a, 3b, 3c, 3d, 3e, 3f), a first distribution valve (4) adapted to connect the outlet side of the cooler (1) to the at least one heat storage device (3a, 3b, 3c, 3d, 3e, 3f) and / or to the braking resistor (2). This makes it possible to integrate the braking resistor into the thermal architecture of a vehicle, i.e., a coolant circuit.

Description

[0001] The present application deals with the integration of a brake resistor into a coolant circuit of a vehicle, in particular a commercial vehicle.

[0002] Vehicles, especially commercial vehicles, usually have a radiator which exchanges heat with the environment, i.e., releases heat energy into the environment.

[0003] In the field of drive technology, and particularly in commercial vehicles, excess braking energy can be converted into braking resistors. First, kinetic energy is converted into electrical energy, for example, in the generator mode of a drive motor. If this energy cannot be used otherwise, it must be converted into a braking resistor. A liquid-cooled braking resistor is particularly suitable for this purpose. The generated heat is then dissipated into the environment via a cooler.

[0004] A liquid-operated braking resistor is known, for example, from document DE 10 2021 202 037 A1. This document describes a particularly simple and efficient design for a liquid-cooled braking resistor, which is capable of dissipating electrical energy in the form of heat into a heat storage medium.

[0005] In current technology, a brake resistor is often integrated with a separate coolant circuit, because a brake resistor can generate a very high amount of heat, which can easily cause other components in a coolant circuit to overheat. However, a separate coolant circuit requires additional installation space and adds weight.

[0006] It is therefore a challenge to integrate a braking resistor into the thermal architecture of an electric vehicle.

[0007] This problem is solved by a coolant circuit according to claim 1 and a vehicle according to claim 10.

[0008] Further advantageous embodiments of the present invention are the subject of the dependent claims.

[0009] A vehicle coolant circuit according to the invention comprises: a radiator configured to dissipate heat to the environment, a brake resistor, a first heat storage device, and a first distribution valve adapted to connect the outlet side of the radiator to the at least one heat storage device and / or the brake resistor. The radiator, the brake resistor, and the at least one heat storage device are generally connected in series; however, the first distribution valve allows the flow through the first heat storage device to be shut off by directing the coolant flow to a first bypass that leads directly to the brake resistor.

[0010] This makes it possible to integrate the brake resistor into a vehicle's thermal architecture, i.e., a coolant circuit. This allows components of the coolant circuit, or other vehicle components and their thermal mass, to be used as primary heat storage devices. Heat generated in a brake resistor can either be dissipated directly by the radiator if the brake resistor is connected to the radiator. However, if the radiator cannot dissipate all the thermal energy, it is also possible for the heat to be temporarily stored in the primary heat storage device by circulating coolant through the radiator and the primary heat storage device.By providing the first distribution valve, it is possible to direct the coolant flow accordingly; either it can only pass through the brake resistor and the radiator (via a first bypass), or the first heat storage device can also be added.

[0011] Preferably, the coolant circuit includes a second distribution valve adapted to connect the first heat storage device to the brake resistor and / or directly to the inlet side of the radiator. The second distribution valve also makes it possible to shut off the flow through the brake resistor by directing the coolant flow exiting the first heat storage device directly to the radiator. Furthermore, the inclusion of a second distribution valve allows for more precise control of the coolant flow: the coolant exiting the first heat storage device can be routed through the brake resistor via the second distribution valve or can be fed directly to the radiator via a second bypass.

[0012] The first heat storage device can therefore be connected directly to the radiator without the coolant having to pass through the brake resistor; this happens, for example, when the first heat storage device has absorbed heat and this heat is to be released again after a braking process.

[0013] Preferably, the coolant circuit includes a pump designed to pump coolant into the circuit. The pump is preferably located between the brake resistor and the first distribution valve. The pump serves to ensure a uniform flow of coolant and to guarantee a specific heat output from the radiator.

[0014] Preferably, the first and / or the second distribution valve is designed as a 3 / 2-way valve. This allows incoming fluid to be discharged to either one or the other outlet, or both. In this way, the coolant flow between the radiator, the first heat storage device, and the brake resistor can be optimally distributed.

[0015] Preferably, the first heat storage device comprises at least one of the following components: a steering system pump, an electric motor inverter, and / or an electric axle, as well as optionally other components. All vehicle components through which coolant flows or around which coolant flows can be suitable heat storage devices. These components all have a large thermal mass and can be heated accordingly when the braking resistor converts a large amount of electrical energy and releases a correspondingly large amount of thermal energy, but the radiator cannot dissipate all of the electrical energy converted into heat to the environment. In this case, the components of the first heat storage device can be heated accordingly, and after the braking process is complete, they can be cooled again by being cooled by coolant flowing through them, which can then be discharged to the environment via the radiator.The first heat storage device therefore functions, so to speak, as an intermediate storage or buffer for heat.

[0016] Preferably, if the first heat storage device comprises several components, these are connected in parallel. This allows excess heat to be distributed among the different components of the first heat storage device – either according to their heat capacities or by means of additional distribution valves. As described above, the first heat storage device as a whole is generally connected in series with the radiator and the braking resistor.

[0017] Preferably, additional distribution valves are also provided to distribute the coolant flow between the multiple components.

[0018] Preferably, a second heat storage device is thermally connected to the braking resistor. This preferably comprises the vehicle body (i.e., the frame) and / or components of the trailer, preferably the trailer body. This is a further intermediate storage device to which the braking resistor can transfer heat, which can later be dissipated (if the braking resistor is cooled but does not itself convert energy). However, the second heat storage device can also directly dissipate energy in the form of heat to the surroundings.This second heat storage device serves as a further buffer, so to speak, in case a lot of electrical energy is converted into heat energy by the braking resistor (and this cannot be dissipated quickly enough by the cooler and the first heat storage device), which can then be easily dissipated to the environment over a certain period of time - either by free convection or with the assistance of a fan.

[0019] A vehicle according to the invention has a coolant circuit dimensioned according to the criteria / aspects described above.

[0020] Preferably, this vehicle is an electric vehicle or an electric commercial vehicle. In such vehicles, the integration of the braking resistor into the vehicle's thermal architecture can be particularly advantageous. This allows for a smaller installation space and a lighter radiator, and thus enables optimal use of existing thermal mass when necessary.

[0021] Advantageous embodiments of the present invention are described in more detail with reference to the accompanying figures. Fig. Figure 1 shows a basic representation of the function of a braking resistor in the thermal architecture of a vehicle. Fig. 2 shows normal operation of the system according to Fig. 1, i.e., that heat from certain vehicle components (pump for steering, e-axle, inverter ...) is transferred to the coolant and then dissipated via the radiator. Fig. 3 shows a braking process in the system according to Fig. 1, in which heat is released by the braking resistance. Fig. Figure 4 showed a second embodiment of the present invention, wherein a second heat storage device is arranged on the braking resistor. Fig. Figure 5 shows a second embodiment during a braking process. Fig. Figure 6 shows normal operation of the second embodiment or operation in which the braking process has just ended. Fig. Figure 7 shows a diagram illustrating the heat generated, heat dissipated by the cooler, and heat absorbed by heat storage devices during normal operation, braking, and after braking.

[0022] Fig. Figure 1 shows a basic circuit diagram of a coolant circuit K according to a first embodiment of the present invention. A radiator 1 is shown, which is connected to a pump 6. A first distribution valve 4 is also included, which allows the coolant leaving the pump 6 to be directed either to the first heat storage device 3 or directly to the braking resistor 2 (via the first bypass 8). The coolant flow leaving the pump 6 can also be split between the first heat storage device 3 and the braking resistor 2. A second distribution valve 5 is provided for the coolant flow leaving the components of the first heat storage device 3, so that coolant flowing from the first heat storage device 3 can either be directed to the braking resistor 2 and then to the radiator 1, or directly to the radiator 1 via a second bypass 9.One component 3a of the first heat storage device 3 can, for example, be an e-axle, a second component 3b of the first heat storage device 3 can, for example, be an inverter for an electric motor, and a third component 3c of the first heat storage device 3 can, for example, be the pump for the power steering system. The first distribution valve 4 and the second distribution valve 5 can thus distribute coolant flows accordingly, so that either the first heat storage device 3, or the brake resistor 2, or both components are supplied with coolant. In this way, the thermal mass of several vehicle components can be used as the first heat storage device 3.

[0023] Fig. Figure 2 shows, as mentioned, the normal operation of the system according to claim 1. Here, the first distribution valve 4 is configured such that all coolant leaving the pump 6 is directed to the first heat storage device 3 and flows through components 3a-3f. The distribution valve 5 is then configured such that the coolant flow leaving the first heat storage device 3 is directed directly to the radiator 1 (i.e., via the second bypass 9). In principle, components 3a-3f of the first heat storage device 3, which here function as heat generators, can thus dissipate heat via the radiator. The braking resistor 2 is not subjected to the coolant flow in this case.Even when a braking process is finished, this circuit is used so that the components 3a-3f of the first heat storage device 3, which have temporarily stored heat during a braking process, can release the heat again; this is represented accordingly by the heat flows Q̇.

[0024] Fig. Figure 3 also shows the first embodiment of the present invention, but here during a braking process. The coolant leaving the pump 6 is directed partly to the first heat storage device 3 and partly to the braking resistor 2. The heat generated in the braking resistor 2 during the braking process is directed to the cooler 1 and dissipated there; this is represented by the heat flow Q̇. The heat that cannot be dissipated by the cooler 1 is temporarily stored by the first heat storage device 3 (more precisely, components 3a and 3f); this is represented by the heat flows Q ̇̇accThis is shown accordingly. Thus, the cooler, the first heat storage device 3, and the braking resistor 2 are connected in series, so that heat generated in the braking resistor is dissipated via the cooler 1 and stored by the first heat storage device 3. Component 3e of the first heat storage device, for example, generates further heat, which must be dissipated – by the heat flow Q̇. dlss as shown. However, there is also a direct connection between the output of pump 6 and the input of brake resistor 2 via the first bypass 8, through which a certain proportion of the coolant is also circulated.

[0025] Fig. Figure 4 shows a second embodiment of the present invention in normal operation (similar to that in Fig. 2) The brake resistor 2 is not subjected to coolant flow here. Unlike in Fig. However, it is noticeable that a second heat storage device 7 is arranged on the braking resistor; this is in Fig. However, 4 is non-functional. This second heat storage device is then only assigned to braking resistor 2.

[0026] Fig. Figure 5 shows a braking operation of a second embodiment of the present invention. Similar to in Fig. The first distribution valve 4 distributes the coolant flow from the pump 6 to the brake resistor 2 on the one hand, and to the first heat storage device 3 with its components 3a-f on the other. The first heat storage device 3 with its components 3a-f (more precisely in Fig. 5 the components 3a and 3f) then in turn store heat as intermediate storage (Q acc For example, component 3e of the first heat storage device generates further heat, which must then be dissipated – by the heat flow Q̇.dlss The second distribution valve 5 is configured such that the coolant flow leaving the first heat storage device 3 is directed directly to the brake resistor 2, generating the corresponding heat (Q̇). dlss ) absorbs, which is then released by cooler 1. This is due to the heat flows Q̇. acc It is indicated that heat from the first heat storage device 3 is temporarily stored; at the same time, heat is also dissipated directly from the braking resistor 2 to the second heat storage device 7 and from there partially dissipated to the environment (Q̇). dlss,env ).

[0027] Fig. 6 is similar to the Fig. 5 - here, however, a state shortly after the braking process is shown. Here, heat from the second heat storage device 7 is also transferred back to the coolant via the brake resistor 2 and thus released to the radiator 1; the remaining heat is released to the environment (Q̇̇). dlss,env ).

[0028] Fig. Figure 7 shows a corresponding heat diagram in the 3 different operating modes, also showing the temperature of the first heat storage device. In normal operation, the heat generated by the first heat storage device is equal to the heat output of the radiator; that is, there is no braking, the braking resistor is not active, all heat sources transfer their heat directly to the coolant, which is then dissipated into the environment by the radiator.

[0029] During braking, the heat generated is higher than during normal operation, and the cooling capacity of the radiator is insufficient to dissipate all of it. For this reason, the first (and possibly second) heat storage device 3 or 7 also absorbs a corresponding amount of heat. The temperature of the respective heat storage device rises.

[0030] In operation after the braking process, the generated heat is again equal to the heat output of the cooler, which means that the temperature of the heat storage device also decreases slowly through free convection, and the generated heat can thus be completely dissipated by the cooler.

[0031] The present invention is not limited to the embodiments mentioned above. For example, it would be possible to provide corresponding shut-off valves for the components of the heat storage device 3a-3f and to selectively control which components of the first heat storage device are active during certain processes. Furthermore, multiple coolers are of course possible. REFERENCE MARK LIST 1 cooler 2 Braking resistor 3a, 3b, 3c, 3d, 3e, 3f first heat storage device 4 first distribution valve 5 second distribution valve 6 pump 7 second heat storage device 8 first bypass 9 second bypass K Coolant circuit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 202 037 A1

[0004]

Claims

[1] Coolant circuit (K) of a vehicle, comprising: a cooler (1) which is designed to dissipate heat to the environment, a braking resistor (2), a first heat storage device (3a, 3b, 3c, 3d, 3e, 3f), a first distribution valve (4) adapted to connect the outlet side of the cooler (1) to the first heat storage device (3a, 3b, 3c, 3d, 3e, 3f) and / or to the braking resistor (2); [2] Coolant circuit (K) according to claim 1, further comprising: a second distribution valve (5) adapted to connect the first heat storage device (3a, 3b, 3c, 3d, 3e, 3f) to the braking resistor (2) and / or directly to the inlet side of the cooler (1). [3] Coolant circuit (K) according to claim 1 or 2, further comprising a pump (6) adapted to pump coolant in the coolant circuit (K), wherein the pump (6) is preferably arranged between the brake resistor (2) and the first distribution valve (6). [4] Coolant circuit (K) according to one of the preceding claims, wherein the first distribution valve (4) and / or the second distribution valve (5) is designed as a 3 / 2-way valve. [5] Coolant circuit (K) according to one of the preceding claims, wherein the first heat storage device comprises: a steering system pump (3a) and / or an inverter (3b) for an electric motor and / or an electric axle (3c), and optionally further components. [6] Coolant circuit (K) according to one of the preceding claims, wherein, if the first heat storage device (3a, 3b, 3c, 3d, 3e, 3f) comprises several components, these are connected in parallel, and corresponding further distribution valves are provided to distribute the coolant flow between the several components. [7] Coolant circuit (K) according to one of the preceding claims, wherein a second heat storage device (7) is thermally connected to the braking resistor (2). [8] Coolant circuit (K) according to claim 7, wherein the second heat storage device (7) is adapted to also release heat to the environment. [9] Coolant circuit (K) according to claim 7, wherein the second heat storage device (7) is / are the body of the vehicle and / or components of the trailer. [10] Vehicle which includes the coolant circuit (K) according to any one of claims 1 to 9, which is preferably an electric vehicle, more preferably an electric commercial vehicle.

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