Monitoring device for a coolant circuit and method for monitoring a coolant level in a coolant circuit

Abstract

Monitoring device set up for a coolant circuit (10) with: at least two temperature sensors (14, 16), each of which can be arranged on and / or in the coolant circuit (10) or is fixedly arranged such that at least two individual temperature values ​​(T1 to T4) of local temperatures of a coolant (12) of the coolant circuit (10) in at least two different partial volumes of the coolant circuit (10) can be measured by means of the at least two temperature sensors (14, 16) arranged on and / or in the coolant circuit (10); and an evaluation device (18) which is designed to calculate at least one difference (Δ1, Δ2) between the individual temperature quantities (T1 to T4) measured in different partial volumes, and, if the at least one difference (Δ1, Δ2) deviates from at least one specified normal range, to output a warning information (20) regarding a low coolant level in the coolant circuit (10).

Description

[0001] The invention relates to a monitoring device for a coolant circuit. The invention also relates to a coolant circuit, drive and / or power electronics for a vehicle, and a battery for a vehicle. Furthermore, the invention relates to a method for monitoring the coolant level in a coolant circuit. State of the art

[0002] German patent DE 10 2015 205 891 A1 describes a vehicle with an electric drive comprising an electric motor, power electronics, and an electrical control system. A coolant circuit filled with a coolant is used to cool the power electronics.

[0003] DE 10 2015 011 117 A1 describes a method for determining the fill level of a coolant in a motor vehicle and a cooling device for cooling an internal combustion engine in a motor vehicle.

[0004] Furthermore, DE 10 2013 219 789 A1 discloses a device and a method for determining the flow velocity of a coolant through a cooling channel. Disclosure of the invention

[0005] The invention provides a monitoring device for a coolant circuit with the features of claim 1, a coolant circuit with the features of claim 6, drive and / or power electronics for a vehicle with the features of claim 7, a battery for a vehicle with the features of claim 8 and a method for monitoring a coolant level in a coolant circuit with the features of claim 9. Advantages of the invention

[0006] The present invention provides a means for reliably detecting a (too) low coolant level in a coolant circuit. By using the present invention, a user of a device cooled by the coolant circuit can therefore be warned in good time by means of a warning message indicating the (too) low coolant level. For example, a driver of a vehicle equipped with the cooled device can be warned in such a timely manner that an undesirable breakdown of the vehicle, particularly in a dangerous location (such as a highway, expressway, or level crossing), due to a malfunction or failure of the device (due to the (too) low coolant level), is avoided.The present invention thus contributes to the improved usability of devices cooled by means of a coolant circuit.

[0007] The present invention is also relatively simple and can be implemented without the need for expensive components. This increases the acceptance of using the present invention in vehicles to improve their safety standards.

[0008] In an advantageous embodiment of the monitoring device, the evaluation unit is designed to detect, based on at least one signal output by at least one pump of the coolant circuit and / or by at least one flow sensor of the coolant circuit, whether the coolant is flowing through the coolant circuit at least at a predetermined minimum flow velocity, and, if necessary, to switch the at least two temperature sensors from a deactivated mode to an active measuring mode. This embodiment of the monitoring device thus takes into account that the technology used for diagnosing the coolant level functions reliably, especially with a moving coolant.In the embodiment of the monitoring device described here, the at least two temperature sensors can therefore be in deactivated mode when the coolant is stationary, thus reducing the energy consumption of the monitoring device and preventing a misdiagnosis of the monitoring device (due to the stationary coolant).

[0009] In a further advantageous embodiment of the monitoring device, the at least two temperature sensors can be arranged on and / or in the coolant circuit or are fixedly mounted such that the distance between any two adjacent temperature sensors arranged on and / or in the coolant circuit is between 1 cm and 10 cm. The at least two temperature sensors are thus reliably suitable for determining local temperatures of the coolant in different subvolumes of the cooling circuit.

[0010] The monitoring device can comprise at least one section of the coolant circuit that can be used or is used in the coolant circuit, and to which the at least two temperature sensors of the monitoring device are attached. Alternatively, the monitoring device can also be designed such that the compact monitoring device can be attached to at least one section of the coolant circuit in such a way that the at least two individual temperature parameters can be measured by means of the at least two temperature sensors arranged on and / or in the coolant circuit.

[0011] For example, the at least two temperature sensors can comprise at least one IGBT temperature sensor and / or at least one DCDC temperature sensor. Such temperature sensor types are cost-effective and require relatively little installation space. The monitoring device according to the invention is therefore comparatively inexpensive and can be manufactured with a small overall installation space requirement. However, it should be noted that the temperature sensor types mentioned here are only examples.

[0012] The advantages described above are also guaranteed in a coolant circuit with such a monitoring device.

[0013] A drive and / or power electronics system for a vehicle with such a monitoring device or a corresponding coolant circuit also enables the advantages described above.

[0014] The advantages described above are also achieved with a battery for a vehicle equipped with such a monitoring device or a corresponding coolant circuit.

[0015] Furthermore, implementing a corresponding method for monitoring the coolant level in a coolant circuit also provides the advantages described above. It is expressly noted that the method for monitoring the coolant level in a coolant circuit can be further developed according to the embodiments of the monitoring device described above. Brief description of the drawings

[0016] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1a to 1e a schematic representation of an embodiment of the monitoring device and coordinate systems to explain its operation; and Fig. 2 a flowchart to explain one embodiment of the method for monitoring a coolant level in a coolant circuit. Embodiments of the invention

[0017] Fig. Figures 1a to 1e show a schematic representation of an embodiment of the monitoring device and coordinate systems to explain its operation.

[0018] The in Fig. The monitoring device shown schematically in Figure 1a can also be referred to as a sensor device or a diagnostic device. The monitoring device is designed to monitor the coolant level of a coolant 12 filled into a (partially shown) coolant circuit / cooling circuit 10, or to perform a diagnosis regarding a potentially (too) low coolant level in the coolant circuit 10. The term "coolant 12" can be understood to mean any cooling medium in its liquid and / or gaseous state.

[0019] Furthermore, the use of the monitoring device is not limited to any specific form / design of the coolant circuit 10, nor to any specific device cooled (at least partially) by means of the coolant circuit 10. The coolant circuit 10 can, for example, be a low-pressure coolant circuit / This is a low-pressure circuit. It is merely an example that the monitoring device for a coolant circuit 10 of a drive and / or power electronics system and / or a battery, such as the drive and / or power electronics system and / or battery of a vehicle, can be used. The vehicle can be, for example, an electric or hybrid vehicle, optionally a small, medium, or luxury vehicle.

[0020] The monitoring device comprises at least two temperature sensors 14 and 16, each of which can be arranged on and / or in the coolant circuit 10 or is fixedly mounted such that at least two individual temperature parameters T1 to T4 of the local temperatures of the coolant 12 of the coolant circuit 10 in at least two different partial volumes of the coolant circuit 10 can be measured by means of the at least two temperature sensors 14 and 16 arranged on and / or in the coolant circuit 10. The individual temperature parameters T1 to T4 can, for example, be temperature values ​​(in degrees Celsius or Kelvin). Likewise, the individual temperature parameters T1 to T4 can also be other physical quantities, such as current values ​​and / or voltage values, which correspond to the local temperatures prevailing in the at least two different partial volumes of the coolant circuit 10.

[0021] The at least two temperature sensors 14 and 16 can, for example, comprise at least one IGBT temperature sensor (insulated-gate bipolar transistor) 14, a power switch with a temperature sensor, and / or at least one DCDC temperature sensor 16. Thus, relatively inexpensive and comparatively small-volume sensor types can be used as temperature sensors 14 and 16 for the monitoring device. However, the sensor types mentioned here are only examples.

[0022] In the embodiment of the Fig. 1a The monitoring device includes, for example, a section 10a of the coolant circuit 10, which can be used or is used in the coolant circuit 10, and to which the at least two temperature sensors 14 and 16 of the monitoring device are attached. The section 10a of the coolant circuit 10 can, for example, be a radiator line 10a, a radiator plate, and / or a radiator housing. The in Fig. The design of the monitoring device shown in Figure 1a allows for a comparatively simple installation of the monitoring device on the coolant circuit 10 by inserting the subsection 10a of the coolant circuit 10 into the coolant circuit 10. The Fig. The design of the monitoring device shown in Figure 1a is to be interpreted only as an example. Alternatively, the monitoring device can also be designed such that it (as a compact component) can be arranged on and / or in at least a section of the (compact) coolant circuit 10 in such a way that the at least two individual temperature parameters T1 to T4 can be measured by means of the at least two temperature sensors 14 and 16 arranged on and / or in the coolant circuit 10.

[0023] The at least two temperature sensors 14 and 16 can be arranged on and / or in the coolant circuit 10 or fixedly mounted such that at least one distance between two adjacent temperature sensors 14 and 16 arranged on and / or in the coolant circuit 10 is between 1 cm and 10 cm. In particular, all distances between two adjacent temperature sensors 14 and 16 arranged on and / or in the coolant circuit 10 (of all temperature sensors 14 and 16 of the monitoring device) can be between 1 cm and 10 cm. This allows for the reliable determination of the individual temperature values ​​T1 to T4 of the local temperatures of the coolant 12. However, it should be noted that the numerical values ​​mentioned here are only to be interpreted as examples.

[0024] The monitoring device also includes an evaluation unit 18 (shown schematically). The evaluation unit 18 is designed to calculate at least one difference Δ1 and Δ2 between the individual temperature values ​​T1 to T4 measured in different partial volumes and, if the at least one difference Δ1 and Δ2 deviates from at least one predefined normal range, to output a warning message 20 regarding a (too) low coolant level in the coolant circuit 10. For example, the evaluation unit 18 is designed to activate a warning light, control a display device to show a warning symbol, control an audio output device to emit an acoustic warning signal, and / or control a transmitter to send a corresponding notification as warning message 20.As an advantageous further development, the evaluation device 18 can also be designed to output information regarding a sufficient coolant level in the coolant circuit, provided that at least one difference Δ1 and Δ2 lies within at least one specified normal value range.

[0025] The monitoring device thus provides the aforementioned advantages, as explained in more detail below.

[0026] The evaluation device 18 can, for example, be designed to calculate the at least one difference Δ1 and Δ2 for individual temperature quantities T1 to T3 measured (almost) simultaneously in different partial volumes. Preferably, the evaluation device 18 is designed to calculate the at least one difference Δ1 and Δ2 as a difference between an individual temperature quantity T1 to T3 measured earlier in a first partial volume and an individual temperature quantity T1 to T3 measured later in a second / different partial volume, wherein for a time difference Δt between a first measurement time of the earlier measured individual temperature quantity T1 to T3 and a second measurement time of the later measured individual temperature quantity T1 to T3, the following (essentially) applies: Δt = Δs / v0, where Δs is a distance between the first partial volume and the second partial volume and v0 is an average flow velocity of the coolant 12 through the coolant circuit 10.

[0027] At the in Fig. In the monitoring device shown schematically in Figure 1a, the evaluation unit 18 is also designed to detect, based on at least one signal 24 output to the evaluation unit 18 from at least one pump 22 of the coolant circuit 10, whether the coolant 12 flows through the coolant circuit 10 at least at a predetermined minimum flow velocity along a flow direction 26. Alternatively or additionally, the evaluation unit can also be designed to detect, based on at least one signal output to the evaluation unit 18 from at least one flow sensor of the coolant circuit 10, the flow of the coolant 12 through the coolant circuit 10 at least at the predetermined minimum flow velocity. If necessary, i.e.,Provided that the coolant 12 flows through the coolant circuit 10 at least at an average flow velocity v0 equal to the specified minimum flow velocity, the evaluation unit 18 is designed to switch the at least two temperature sensors 14 and 16 from a deactivated mode to an active measurement mode. Preferably, the evaluation unit 18 is also designed to switch the at least two temperature sensors 14 and 16 to the deactivated mode if it detects that the coolant 12 is flowing through the coolant circuit 10 at an average flow velocity v0 below the specified minimum flow velocity (e.g., an average flow velocity v0 equal to zero).Optionally, the evaluation device 18 can also be designed to briefly activate at least one pump 22 of the coolant circuit 10 (at least for investigating the coolant level in the coolant circuit 10) so that the mean flow velocity v0 of the coolant 12 is at least equal to the specified minimum flow velocity.

[0028] The diagnostic technique used by evaluation unit 18 is described below with reference to the coordinate systems of the Fig. 1b to 1e explained in more detail, with one abscissa of the coordinate systems of the Fig. 1b to 1e represents a time axis t, while an ordinate of the coordinate systems of Fig. 1b and Fig. 1d a power loss P of the at least two temperature sensors 14 and an ordinate of the coordinate systems of the Fig. 1c and Fig. 1e reproduce 14 individual temperature values ​​F1 to F3 measured by at least two temperature sensors.

[0029] Using the coordinate systems of Fig. 1b and Fig. Figure 1c depicts a situation in which there is a sufficient level of coolant 12 in the coolant circuit 10. At time t1, the evaluation unit 18 switches the temperature sensors 14 and 16, which were previously in their deactivated mode (with a power loss P of almost zero), to active measurement mode (with a power loss P equal to the operating power P0). After a coolant level diagnosis is performed, the temperature sensors 14 and 16 are switched back to deactivated mode at time t2, so that a power loss P equal to the operating power P0 occurs at the temperature sensors 14 and 16 only between times t1 and t2.

[0030] Into the coordinate system of Fig. Figure 1c shows the individual temperature values ​​T1 to T3 measured by temperature sensors 14 between times t1 and t2. The evaluation unit 18 is designed to calculate a first difference Δ1 between two temperature values ​​T2 and T3 (measured within a corresponding time difference Δt) and a second difference Δ2 between two individual temperature values ​​T1 and T3 (measured within a further corresponding time difference Δt). (This can be described as a mutual comparison of the individual temperature values ​​T1 to T3.)

[0031] In the example presented here, the normal ranges are defined such that a first difference Δ1 is below 5 K (Kelvin) and a second difference Δ2 is below 10 K (Kelvin) within the normal ranges. This is the case in the example of Fig. 1b and Fig. 1c is the case. The evaluation unit 18 thus recognizes, based on the differences Δ1 and Δ2, that the coolant circuit 10 is sufficiently filled with the coolant 12.

[0032] In contrast, the coordinate systems of Fig. 1d and Fig. 1e depicts a situation in which the coolant level in coolant circuit 10 is (too) low. This also applies to the example of... Fig. 1d and Fig. In 1e, the temperature sensors 14 and 16 are switched from their deactivated mode to their active measurement mode exclusively between times t1 and t2. This can be seen from the coordinate system of the Fig. 1e entered individual temperature quantities T1 to T3, that a first difference Δ1' between two (measured within the corresponding time difference Δt) individual temperature quantities T2 and T3 and a second difference Δ2' between two (measured within the further corresponding time difference Δt) individual temperature quantities T1 and T3 (compared to the example of the Fig. 1b and Fig. 1c) are significantly increased. In the example of the Fig. 1d and Fig. If the first difference Δ1' is greater than 5 K (Kelvin) and the second difference Δ2' exceeds 10 K (Kelvin), then the differences Δ1 and Δ2 lie outside the specified normal ranges.

[0033] The observed increase in the differences Δ1 and Δ2 is due to the (too) low coolant level in the coolant circuit 10. For example, air bubbles 28 in the coolant 12 can counteract a uniform temperature distribution in the coolant 12. However, even without the presence of air bubbles 28, a (too) low coolant level counteracts a uniform temperature distribution in the coolant 12.

[0034] Optionally, an additional temperature sensor 16, preferably of a different type than the temperature sensors 14, can be used to investigate potential faults in the individual temperature values ​​T1 to T3 of the temperature sensors 14. If an individual temperature value T4 measured by the temperature sensor 16 is relatively close to the individual temperature values ​​T1 to T3 measured by the temperature sensors 14, it can be concluded that the temperature sensors 14 are functioning correctly and providing reliable individual temperature values ​​T1 to T3. Differences Δ1 and Δ2 outside the normal ranges are therefore attributable to a (too) low coolant level in the coolant circuit 10.

[0035] The advantages of the monitoring device described above are also guaranteed in a coolant circuit 10 with such a “built-in” / “integrated” monitoring device.

[0036] Fig. Figure 2 shows a flowchart to explain one embodiment of the method for monitoring a coolant level in a coolant circuit.

[0037] The procedure described below is initiated by a process step S0. The procedure is initiated, for example, whenever a device cooled by the coolant circuit, such as one installed in a vehicle, is started. Similarly, ignition of the vehicle equipped with the device can also trigger the start of the procedure. Optionally, the procedure can also be initiated repeatedly at a predetermined repetition rate during operation of the device (or during driving of the vehicle equipped with the device).

[0038] Optionally, in process step S0, it can be investigated whether a coolant in the coolant circuit flows through the circuit at least at a predetermined minimum flow velocity. For example, it can be examined whether at least one pump in the coolant circuit is operated at at least at a predetermined minimum pumping rate (corresponding to the minimum flow velocity). If the at least one pump in the coolant circuit is operated at at least at the predetermined minimum pumping rate, it can be concluded / determined that the coolant flows through the coolant circuit at least at the predetermined minimum flow velocity.Otherwise, it can be assumed that the average flow velocity of the coolant is below the specified minimum flow velocity. Alternatively or additionally, at least one flow sensor can be used to measure the average flow velocity of the coolant through the coolant circuit.

[0039] In process step S1, at least two individual temperature parameters are measured as local temperatures of the coolant in at least two different partial volumes of the coolant circuit. Examples of the at least two individual temperature parameters have already been mentioned above. For example, at the beginning of process step S1, at least two temperature sensors used to measure the at least two individual temperature parameters can be switched from a deactivated mode to an active measurement mode. In this case, process step S1 is preferably executed only if the coolant in the coolant circuit flows through the circuit at least at the specified minimum flow velocity. (Otherwise, i.e.,The process can be aborted if the average flow velocity of the coolant is below the specified minimum flow velocity.

[0040] In the method of the Fig.In the embodiment of the method shown in Figure 2, an optional process step S2 is executed after process step S1. In this step, the power loss occurring in the at least two temperature sensors during the execution of process step S1 is evaluated. If the power loss is within a defined operating range, it can be concluded that the at least two temperature sensors are operating correctly, and the method can be continued with process step S3. Otherwise, i.e., if the power loss is outside the defined operating range, the process can return to process step S0. However, process step S2 can also be omitted.

[0041] In process step S3, at least one difference between the individual temperature values ​​measured in different partial volumes is calculated. The measurement times for the individual temperature values ​​used to calculate this difference are described in the examples above. In a further process step S4, this difference is compared to at least one standard range. If the difference deviates from at least one predefined standard range, process step S5 generates a "suspected error" warning regarding a potentially low coolant level. If the difference between the individual temperature values ​​measured in different partial volumes falls within the standard range, the process can return to step S0.

[0042] After process step S5, an optional process step S6 is executed, in which a possible error in the individual temperature values ​​measured in different partial volumes and evaluated in process step S3 is investigated. For this purpose, an additional individual temperature value / reference individual temperature value, which was preferably measured during process step S1 using an additional temperature sensor (such as a DC-DC temperature sensor), is used. If a comparison of the additional individual temperature value / reference individual temperature value with the individual temperature values ​​evaluated in process step S3 shows (substantial) agreement, then in process step S7, a warning information regarding a (too) low coolant level is issued to a user of the coolant circuit.However, if process step S6 reveals that the individual temperature values ​​evaluated in process step S3 deviate significantly from the subsequent individual temperature value / reference individual temperature value, the procedure described here can be repeated. Alternatively, instead of process steps S5 and S6, one can proceed directly to process step S7.

[0043] The method described above is just as versatile as the monitoring device explained previously. Reference symbol list 10 Coolant circuit / Cooling circuit 10a Subsection 12 Coolants 14, 16 temperature sensors 18 Evaluation unit 20 Warning information 22 Pump 24 Signal 26 Flow direction / direction of flow 28 air bubbles Δ1, Δ2 differences P Power loss P0 Operating power S0, S1 - S7 process steps t, t1, t2 times T1 - T4 Individual temperature parameters

Claims

Monitoring device configured for a coolant circuit (10) comprising: at least two temperature sensors (14, 16), each of which can be arranged on and / or in the coolant circuit (10) or is fixedly arranged such that at least two individual temperature values ​​(T1 to T4) of local temperatures of a coolant (12) of the coolant circuit (10) can be measured in at least two different partial volumes of the coolant circuit (10) by means of the at least two temperature sensors (14, 16) arranged on and / or in the coolant circuit (10); and an evaluation device (18) which is designed to calculate at least one difference (Δ1, Δ2) between the individual temperature values ​​(T1 to T4) measured in different partial volumes, and, if the at least one difference (Δ1, Δ2) deviates from at least one predetermined normal value range, to output a warning message (20) regarding a low coolant level in the coolant circuit (10). Monitoring device according to claim 1, wherein the evaluation device (18) is designed to detect, on the basis of at least one signal (24) output by at least one pump (22) of the coolant circuit (10) and / or by at least one flow sensor of the coolant circuit (10), whether the coolant (12) flows through the coolant circuit (10) at least at a predetermined minimum flow velocity, and, if necessary, to control the at least two temperature sensors (14, 16) from a deactivated mode into an active measurement mode. Monitoring device according to claim 1 or 2, wherein the at least two temperature sensors (14, 16) can be arranged on and / or in the coolant circuit (10) or are fixedly arranged such that at least one distance between two adjacent temperature sensors (14, 16) arranged on and / or in the coolant circuit (10) is between 1 cm and 10 cm. Monitoring device according to one of the preceding claims, wherein the monitoring device comprises at least one subsection (10a) of the coolant circuit (10) which can be inserted or is inserted in the coolant circuit (10) and to which the at least two temperature sensors (14, 16) of the monitoring device are attached. Monitoring device according to one of the preceding claims, wherein the at least two temperature sensors (14, 16) comprise at least one IGBT temperature sensor (14) and / or at least one DCDC temperature sensor (16). Coolant circuit (10) with a monitoring device according to one of the preceding claims. Drive and / or power electronics for a vehicle with a monitoring device according to one of claims 1 to 5 or a coolant circuit (10) according to claim 6. Battery for a vehicle with a monitoring device according to one of claims 1 to 5 or a coolant circuit (10) according to claim 6 . Method for monitoring a coolant level in a coolant circuit (10) comprising the steps: measuring at least two individual temperature quantities (T1 to T4) of local temperatures of a coolant (12) of the coolant circuit (10) in at least two different partial volumes of the coolant circuit (10) (S1); calculating at least one difference (Δ1, Δ2) between the individual temperature quantities (T1 to T4) measured in different partial volumes (S3); and, if the at least one difference (Δ1, Δ2) deviates from at least one specified normal range (S4), issuing a warning message (20) regarding a low coolant level (S5, S7). Method according to claim 9, wherein at least two temperature sensors (14, 16), by means of which the at least two individual temperature quantities (T1 to T4) are measured, are controlled from a deactivated mode to an active measurement mode only if the coolant (12) flows through the coolant circuit (10) at least at a predetermined minimum flow velocity. Method according to claim 10, wherein it is determined that the coolant (12) flows through the coolant circuit (10) at least at the specified minimum flow velocity when at least one pump (22) of the coolant circuit (10) is operated at least at a specified minimum pump rate (S0).

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