Integration of a braking resistor into a coolant circuit of a vehicle

Abstract

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

Description

[0001] 2024PF00254 September 2, 2024

[0002] 1

[0003] DESCRIPTION

[0004] Integration of a brake resistor into a vehicle's coolant circuit

[0005] The present application deals with the integration of a brake resistor into a coolant circuit of a vehicle, in particular a commercial vehicle.

[0006] Vehicles, especially commercial vehicles, usually have a radiator which exchanges heat with the environment, i.e., releases heat energy into the environment.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] It is therefore a challenge to integrate a braking resistor into the thermal architecture of an electric vehicle. 2024PF00254

[0011] 2

[0012] This problem is solved by a coolant circuit according to claim 1 and a vehicle according to claim 10.

[0013] Further advantageous embodiments of the present invention are the subject of the dependent claims.

[0014] A coolant circuit according to the invention for a vehicle 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.

[0015] 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.

[0016] Preferably, the coolant circuit has a second distribution valve adapted to connect the first heat storage device to the brake resistor and / or 2024PF00254

[0017] 3. to connect directly to the inlet side of the cooler. The second distribution valve also makes it possible to shut off the flow through the brake resistor by directing the coolant flow leaving the first heat storage device directly to the cooler. Furthermore, the 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 it can be fed directly to the cooler via a second bypass.

[0018] 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.

[0019] 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 also to guarantee a specific heat output from the radiator.

[0020] 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.

[0021] 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 heat up accordingly when the braking resistor converts a large amount of electrical energy and thus generates a correspondingly large amount of heat. 2024PF00254

[0022] 4. Thermal energy is released, 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 circulated with coolant, which can then be released into the environment via the radiator. The first heat storage device thus acts as an intermediate storage or buffer for heat.

[0023] 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.

[0024] Preferably, additional distribution valves are also provided to distribute the coolant flow between the multiple components.

[0025] 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 acts as a further buffer in case a large amount 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). In this way, the excess heat can be easily dissipated to the environment over a certain period of time – either by free convection or with the assistance of a fan. 2024PF00254.

[0026] 5

[0027] A vehicle according to the invention has a coolant circuit dimensioned according to the criteria / aspects described above.

[0028] 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.

[0029] Advantageous embodiments of the present invention are described in more detail with reference to the accompanying figures.

[0030] Fig. 1 shows a basic representation of the function of a braking resistor in the thermal architecture of a vehicle.

[0031] Fig. 2 shows normal operation of the system according to Fig. 1, i.e., heat from certain vehicle components (pump for steering, e-axle, inverter ...) is transferred to the coolant and then dissipated via the radiator.

[0032] Fig. 3 shows a braking process in the system according to Fig. 1, in which heat is released by the braking resistor.

[0033] Fig. 4 showed a second embodiment of the present invention, wherein a second heat storage device is arranged on the braking resistor.

[0034] Fig. 5 shows a second embodiment during a braking process.

[0035] Fig. 6 shows normal operation of the second embodiment or operation in which the braking process has just ended.

[0036] Fig. 7 shows a diagram illustrating the heat generated, heat dissipated by the radiator, and heat absorbed by heat storage devices during normal operation, braking, and after braking. 2024PF00254

[0037] 6

[0038] Fig. 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.

[0039] As mentioned, Fig. 2 shows the normal operation of the system according to claim 1. Here, the first distribution valve 4 is configured so 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 so 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. This configuration is also used when a braking process is completed so that components 3a-3f of the first 2024PF00254

[0040] 7

[0041] Heat storage device 3, which has temporarily stored heat during a braking process and can therefore release the heat again, is represented accordingly by the heat flows Q.

[0042] Fig. 3 also shows the first embodiment of the present invention, here, however, during a braking process. The coolant leaving the pump 6 is directed partly to the first heat storage device 3 and partly to the brake resistor 2. The heat generated in the brake resistor 2 during the braking process is directed to the cooler 1 and dissipated there; this is represented by the heat flow Q. 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 Q. 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.

[0043] Fig. 4 shows a second embodiment of the present invention in normal operation (similar to Fig. 2). Here, the brake resistor 2 is not supplied with coolant. In contrast to Fig. 2, however, a second heat storage device 7 is arranged on the brake resistor; this device is non-functional in Fig. 4. This second heat storage device is then only associated with the brake resistor 2.

[0044] Fig. 5 shows a braking operation of a second embodiment of the present invention. Similar to Fig. 3, the first distribution valve 4 distributes the coolant flow from the pump 6 to the braking 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 2024PF00254

[0045] 8

[0046] Components 3a and 3f then store heat as intermediate storage (Qacc). For example, component 3e of the first heat storage device generates further heat, which must then be dissipated – by the heat flow Q. 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, where it generates the corresponding heat (Q). dlss ) absorbs, which is then released by cooler 1. This is due to the heat flows Q acc It is indicated that heat from the first heat storage device 3 is temporarily stored; simultaneously, heat from the braking resistor 2 is also dissipated directly to the second heat storage device 7 and from there partially dissipated to the environment (Q). dlsS ' )env ).

[0047] Fig. 6 is similar to Fig. 5 – however, it shows a state shortly after the braking process. Here, heat from the second heat storage device 7 is also transferred back to the coolant via the braking resistor 2 and thus released to the radiator 1; the remaining heat is released to the environment (Q). dlsS ' )env )■

[0048] Fig. 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 to the environment by the radiator.

[0049] 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.

[0050] During operation after braking, the generated heat is equal to the cooling capacity of the radiator. This means that the temperature of the heat storage device also decreases slowly through free convection, and the generated heat can therefore be completely dissipated by the radiator. 2024PF00254

[0051] 9

[0052] 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.

[0053] 2024PF00254

[0054] 10

[0055] REFERENCE MARK LIST

[0056] 1 cooler

[0057] 2 Braking resistor

[0058] 3a, 3b, 3c, 3d, 3e, 3f first heat storage device

[0059] 4 first distribution valve

[0060] 5 second distribution valve

[0061] 6 pump

[0062] 7 second heat storage device

[0063] 8 first bypass

[0064] 9 second bypass

[0065] K Coolant circuit

Claims

2024PF00254 11 PATENT CLAIMS 1. Coolant circuit (K) of a vehicle, comprising: a radiator (1) which is configured to dissipate heat to the environment, a brake resistor (2), a first heat storage device (3a, 3b, 3c, 3d, 3e, 3f), a first distribution valve (4) which is adapted to connect the outlet side of the radiator (1) to the first heat storage device (3a, 3b, 3c, 3d, 3e, 3f) and / or to the brake 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 pump of the steering system (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 2024PF00254 12 are available to distribute the coolant flow between the multiple 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 transfer 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 comprising the coolant circuit (K) according to any one of claims 1 to 9, which is preferably an electric vehicle, further preferably an electric commercial vehicle.

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