Procedure for determining whether a minimum fill level has been reached in a liquid container of a vehicle

Abstract

Method for determining whether a minimum fill level (30) in a liquid container (10) of a vehicle has been breached, comprising the following steps: - Monitoring the fill level (20) of the liquid container (10) with reference to the minimum fill level (30), - Generating a warning signal (40) when the minimum fill level (30) is undershot, - Monitoring at least one vehicle dynamics parameter (50), - Suppressing the output of the warning signal (40) when at least one vehicle dynamics parameter (50) exceeds a predetermined dynamics limit (52), wherein at least two different vehicle dynamics parameters (50) are monitored, wherein a specific dynamics limit (52) is predetermined for each vehicle dynamics parameter (50), and wherein at least one additional combinational dynamics limit (52) is predetermined for each of the at least two vehicle dynamics parameters (50).

Description

[0001] The present invention relates to a method for determining when a minimum fill level in a liquid container of a vehicle is undershot and to a corresponding monitoring device for carrying out such a method.

[0002] It is known that liquids are stored in vehicles. These liquids can be, for example, operating fluids such as fuel, windshield washer fluid or coolant. An expansion tank for engine oil can also be understood as liquid storage in the vehicle. For any liquid storage, liquid containers are usually provided in the vehicle. Depending on the type of liquid stored, monitoring the fill level within the liquid container is necessary. This is often provided by appropriate sensors which are able to provide the actual state with regard to the level in the liquid container. Various devices and methods for determining liquid levels in containers are known from DE 10 2009 039 145 A1, DE 100 05 185 A1, DE 43 15 519 A1, US 3,675,227 A and US 2010 / 0145638 A1.

[0003] A disadvantage of known solutions is that the fluid level in the reservoir can be affected under certain driving situations. For example, when cornering, driving uphill or downhill, accelerating or braking, a corresponding lateral force can act on the fluid in the reservoir. This leads to the corresponding level within the fluid reservoir adjusting and thus shifting to the side. This no longer results in a single, uniform water level, but rather a highest and lowest water level due to the angular adjustment. Since the sensors for determining the water level are usually only arranged at one position within the fluid reservoir, the value measured by the sensor corresponds to the water level at this location.If the water level has been adjusted at an angle due to the influence of lateral forces, this information about the water level, which is purely related to the specific location, can provide no or only very little information about the actual liquid level within the liquid container. It has already been proposed to make a correction for such situations. Something like this is described, for example, in EP 1 063 498 A2 or DE 10 2012 001 580 A1. However, what these solutions have in common is that a great deal of effort is required to computationally determine the actual value for the liquid level within the liquid container. A large number of input parameters must be taken into account in real time. This leads to a high computational effort and correspondingly high costs for implementing such a process.

[0004] The object of the present invention is to at least partially remedy the disadvantages described above. In particular, the object of the present invention is to prevent misdiagnosis regarding the minimum fill level in a liquid container in a cost-effective and simple manner.

[0005] The above object is achieved by a method having the features of claim 1 and a monitoring device having the features of claim 10. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the monitoring device according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0006] A method according to the invention is used to determine when a minimum fill level in a vehicle's fluid reservoir has been undershot. For this purpose, the method according to the invention comprises the following steps: - Monitoring the level of the liquid container with reference to the minimum level, - Generating a warning signal when the minimum level is reached, - Monitoring at least one vehicle dynamics parameter, - Suppressing the output of the warning signal if the at least one vehicle dynamics parameter exceeds a predetermined, in particular applicable, dynamic limit value.

[0007] A method according to the invention is therefore based on the known simple monitoring logic of the liquid level within the liquid container. The fill level is thus monitored essentially regularly or continuously by an appropriate sensor system. This is preferably done in a location-specific manner, so that the fill level is monitored at a specific location within the liquid container. A digital sensor, preferably in the form of a reed sensor, can be used as the sensor. For normal situations, a method according to the invention therefore behaves similarly to known methods in which corresponding information about the fill level is output. A method according to the invention can be used for both a quantitative and a qualitative determination of the fill level.However, in order to achieve the greatest possible reduction in the complexity of a method according to the invention, it is advantageous to implement digital monitoring to detect when the minimum fill level is undershot. This involves qualitative monitoring of the fill level between sufficient filling and undershooting the minimum fill level.

[0008] If a driving situation occurs during use of the vehicle in which a shift or angular adjustment of the level within the fluid reservoir is highly likely, the invention allows for a reaction to this information. The influence of lateral forces can be measured in a vehicle in a variety of ways. For example, sensors are already available that monitor the current force acting on the vehicle for driver assistance systems. Examples include sensors such as those used as acceleration sensors for ABS systems or airbag systems. Of course, additional and independent sensor technology can also be used for a method according to the invention.

[0009] In a method according to the invention, an application is carried out, in particular, on a control unit of a vehicle or a vehicle engine. This application includes the specification of the dynamic limit value. Thus, during the application, and taking into account the type of fluid container and possibly other factors, the dynamic limit value can be specified in a specific manner.

[0010] It is particularly important to note that, according to the invention, the corresponding warning signal is always generated when the minimum fill level is undershot. This allows this first part of the process to be standardized, and the subsequent warning logic is also unambiguous. This results in the vehicle occupant being alerted when the warning signal is generated and after the warning signal has been transmitted. This can be provided, for example, by a display within the cockpit in the form of a corresponding warning light.

[0011] A key aspect of the invention is that after the warning signal is generated and before it is transmitted, this warning signal is suppressed. The suppression of this warning signal occurs depending on the current driving situation. The current driving situation is assessed and evaluated in relation to the current driving dynamics.

[0012] A vehicle dynamics parameter is therefore a parameter that reflects the current driving situation of the vehicle with regard to its force influence. In particular, lateral forces acting on the vehicle are considered to be vehicle dynamics parameters. It should also be noted that vehicle dynamics parameters refer specifically to a moving vehicle. However, there are also application situations, such as a vehicle parked on an inclined surface, which can provide a vehicle dynamics parameter in the form of an inclination angle when the vehicle is stationary.

[0013] For each dynamic vehicle parameter, at least one predefined dynamic limit value is provided. This dynamic limit value specifies the threshold above which the current dynamic vehicle situation is considered critical with regard to determining the fill level. In such a case, this means that the lateral force, for example, when cornering, has become so great that the angle of the fluid level within a fluid reservoir can no longer ensure a realistic and meaningful determination of the actual fill level. Although a warning signal is still generated, its output is actively suppressed.

[0014] A method according to the invention includes the simple solution of digitally monitoring the fill level in the liquid container. However, the generated warning signal is now superimposed according to the invention before it is output and can be suppressed accordingly. The generation of the warning signal and the display of the warning signal in the vehicle can be adopted as standard interfaces from known vehicles or known solutions. According to the invention, the interface between these two method steps is now suppressed, so that the output or transmission of the warning signal is prevented if there is a high probability that the warning signal was generated incorrectly.

[0015] In contrast to the known solutions with correction values, no determination of the actual fill level is performed in the suppression state during high driving dynamics applications, and in particular, no correction is performed. Rather, no calculation is required; the warning signal is only considered if it is highly meaningful information based on the driving dynamics situation.

[0016] A method according to the invention can also reduce the size of the liquid containers. The actual fill level can also be reduced, since a higher fill level is no longer necessary to prevent unwanted false triggering of a warning signal.

[0017] A method according to the invention can be further developed in such a way that the monitoring of the fill level of the liquid container only distinguishes between the following two situations: - The fill level is at or above the minimum fill level, - The fill level is below the minimum fill level.

[0018] The above list therefore represents digital, qualitative monitoring of the fill level. This further reduces the cost and, above all, the complexity of implementing this step. Only a digital 0-1 switch is required, which generates a corresponding switching signal in the form of a warning signal when the fill level falls below the predefined minimum level. This eliminates the need for quantitative determination and the associated complexity. In particular, because a method according to the invention prevents false triggering in the presence of high transverse forces, a reduction in complexity with simplified sensor technology can now be implemented without the undesirable risk of the liquid container running dry.

[0019] It is also advantageous if at least one of the following vehicle dynamics parameters is monitored in a method according to the invention: - Lateral acceleration - Longitudinal acceleration - Vehicle's inclination angle - Vehicle engine temperature.

[0020] The above list is not exhaustive. Of course, two or even more vehicle dynamics parameters can be monitored in parallel. This allows both an individual consideration of each vehicle dynamics parameter with regard to a specific dynamic limit value, or a combination of these. Lateral acceleration is attributable to a corresponding acceleration when the vehicle starts moving or brakes. Cornering, driving uphill, or downhill can also generate corresponding lateral forces. The vehicle's inclination angle can be used as a vehicle dynamics parameter both when moving and when stationary on an inclined surface. Other environmental parameters, such as engine temperature, or in special cases, the vehicle's exterior temperature, can also be corresponding vehicle dynamics parameters.Even though temperature values ​​generally have no direct correlation with the dynamic situation of the vehicle, they form a possible basis for the behavior of the respective fluid in a dynamic situation within the meaning of the present invention. Preferably, sensors or sensor devices that are already present in the vehicle for other systems are used. Examples include ABS sensors with corresponding acceleration sensors. Thus, a method according to the invention can be implemented in existing devices in a vehicle without significant additional costs in order to achieve the advantages of the invention.

[0021] A further advantage can be achieved if, in a method according to the invention, the suppression of the output of the warning signal continues for a predefined period of time after the at least one driving dynamics vehicle parameter has fallen below the predetermined dynamic limit. Therefore, if a method according to the invention has determined that a vehicle is in a driving dynamics situation that does not allow a regular determination of the fill level within the fluid reservoir, this suppression continues for a predefined period of time, even if the driving dynamics situation has already ended. For example, if a vehicle negotiates a bend, this leads to a lateral force being applied. This results in an adjusted fluid level within the fluid reservoir.Based on the information from the sensors, the generated warning signal is now suppressed by an appropriate procedure and not issued. If the vehicle is then steered back onto a straight road, the lateral force is reduced so that the corresponding dynamic limit is no longer exceeded. However, since the fluid level within the fluid reservoir most likely has to settle down again first, the warning signal can be continuously suppressed with regard to its output during this settling-down period. This prevents the warning signal from being activated too quickly from having an after-effect of the dynamic driving situation and thus also leading to an undesired output of the warning signal. This predefined period can therefore be a so-called decay time or hold-up time.

[0022] It is further advantageous if, in a method according to the invention, at least two different vehicle dynamics parameters are monitored, with a specific dynamic limit value being specified for each vehicle dynamics parameter. As already explained, many different vehicle dynamics parameters can exert different influencing forces on the fluid in the respective fluid container. For each vehicle dynamics parameter, a corresponding specific dynamic limit value can be stored, for example, in a stored table. This ensures a further increase in the accuracy of the method according to the invention and, consequently, a further reduction in the risk of false triggering of the warning signal and its output.

[0023] It is also advantageous if, in a method according to the invention, at least one additional combinatorial dynamic limit value is specified for each of the at least two vehicle dynamics parameters. Thus, when considering individual vehicle dynamics parameters in isolation, a higher limit for the dynamic limit value may be decisive than in the combined situation of different vehicle dynamics parameters. For example, the influence on the sensor signal within the fluid reservoir during a downhill drive with steep inclination angles and a gentle curve may be just as great and thus considered risky as a steeper curve with stronger lateral acceleration when driving straight ahead on a level stretch. Thus, the combination of different dynamic limit values ​​as combinatorial dynamic limit values ​​also provides additional safety in order to achieve the advantages according to the invention.

[0024] It is also advantageous if, in a method according to the invention, the specified dynamic limit value can be changed as a function of at least one input value. Such input values ​​can be provided, for example, by a corresponding application in an engine control unit. They serve to implement a corresponding adjustment of the specified dynamic limit values.

[0025] It is further advantageous if a method according to the invention is used in at least one of the following liquid containers of a vehicle: - Coolant expansion tank - Engine oil tank - Fuel tank - Windscreen washer tank

[0026] The above list is not exhaustive. Of course, corresponding procedural rules according to the invention can also be applied to several or even all liquid containers in the vehicle.

[0027] It is further advantageous if, in a method according to the invention, the step of suppressing the output of the warning signal is carried out by generating and outputting a suppression signal. As already explained, according to the invention, the warning signal is always generated when the minimum fill level is undershot, i.e., even in highly dynamic driving situations. In order to implement the suppression according to the invention, it is now possible to also provide this suppression in the form of a suppression signal. The suppression signal thus serves to be able to implement the suppression in a corresponding suppression device based on this signal for the output of the warning signal.

[0028] The present invention also relates to a monitoring device for monitoring the fill level of a liquid container of a vehicle. This monitoring device has at least one sensor device for monitoring the fill level of the liquid container with reference to a minimum fill level. Furthermore, at least one second sensor device is provided for monitoring at least one vehicle dynamics parameter. A monitoring device according to the invention is characterized in that a control unit is provided for carrying out a method according to the invention. Thus, a monitoring device according to the invention offers the same advantages as those explained in detail with reference to a method according to the invention.

[0029] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show schematically: Fig. 1 shows a first embodiment of a liquid container with a monitoring device according to the invention, Fig. 2 the embodiment of the Fig. 1 in a highly dynamic driving situation, Fig. 3 a partial area of ​​a monitoring device according to the invention and Fig. 4 a schematic diagram representation of a signal curve.

[0030] In the Fig. 1 and Fig. Figure 2 schematically shows a first embodiment of a monitoring device 100 according to the invention. This monitoring device 100 has different types of sensor devices 110 and 120. On the one hand, a plurality of second sensor devices 120 are provided in order to be able to detect and transmit vehicle dynamics parameters 50. Furthermore, a liquid container 10 is provided, for example in the form of an expansion tank for a coolant of an engine cooling system. A corresponding liquid with a fill level 20 is arranged in this liquid container 10. The Fig. 1 shows two different filling levels 20. As a solid line, the upper filling level 20 is a filled liquid container 10. For example, due to consumption of the stored liquid, this filling level 20 will decrease, so it can fall below a minimum filling level 30 at a certain time, until it reaches, for example, the position you see as filling level 20 with a dashed line in Fig. 1 is shown.

[0031] The first sensor device 110 is designed, in particular, as a digital sensor device for distinguishing whether the minimum fill level 30 is exceeded or not reached. For example, the first sensor device 110 can be designed as a reed contact. If the minimum fill level 30 is undershot, as occurred by the fill level 20 according to the dashed line, a corresponding warning signal 40 is generated by the first sensor device 110. This generated warning signal 40 can be forwarded to an output device 140, where it can provide the driver with the corresponding information as a warning signal within the vehicle.

[0032] In addition to normal conditions, in highly dynamic driving situations of the vehicle, an angular setting of the liquid level within the liquid container 10 can occur. Such a situation is in Fig. 2. Starting from the liquid level 20 according to Fig. 1, no fluid consumption has occurred, but rather, a transverse force is applied from left to right, for example, by cornering. As a result, the corresponding fluid level rises sharply at the same fluid level 20. This causes the first sensor device 110 to generate and transmit a corresponding warning signal 40.

[0033] In Fig. Figure 3 schematically illustrates how a corresponding monitoring device can suppress the output of the warning signal 40. A control unit 130 is provided for the monitoring device 100. This control unit 130 collects the information from the sensor devices 110 and 120. The warning signal 40 reaches this control unit 30 in the same way as the at least one vehicle dynamics parameter 50. If the at least one vehicle dynamics parameter 50 is above a corresponding dynamic limit value 52, this is determined in a corresponding comparison unit 134. A suppression signal can then be generated, which suppresses the output of the generated warning signal 40 in a corresponding suppression unit 132. Fig. 2, this results in the warning signal being suppressed due to the detection of the high driving dynamics situation. Although the warning signal 40 was generated by the first sensor device 110, the warning signal 40 is not forwarded to the output device 140.

[0034] Fig. Figure 4 schematically shows a possible progression of corresponding signals. Thus, the fluid level 20 can change due to corresponding vehicle dynamics parameters 50. If it is determined from left to right over time that a vehicle dynamics parameter 50, for example in the form of a lateral force or lateral acceleration, is increasing, this increase can be monitored in comparison to an exceedance of a dynamic limit value 52. In the same way, for example, a drop in the fluid level 20 as a result of this lateral force influence in the Fig. 4. The liquid level 20 falls below a minimum level 30. These two phases are known as phases II and I of the process in Fig. 4. However, falling below the minimum fill level 20 leads to the generation of a warning signal 40 but not to the output of a warning signal 40, since this phase I is within phase II, in which this output is suppressed.

[0035] The above explanation of the embodiments describes the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention. List of reference symbols 10 liquid containers 20 Fill level 30 Minimum fill level 40 warning signal 42 Suppression signal 50 driving dynamics vehicle parameters 52 Dynamic limit 100 monitoring device 110 first sensor device 120 second sensor device 130 Control unit 132 Suppression Unit 134 Comparison unit 140 Dispensing device I Phase of the procedure II Phase of the procedure

Claims

[1] Method for determining whether a minimum fill level (30) in a liquid container (10) of a vehicle has been undershot, comprising the following steps: - monitoring the fill level (20) of the liquid container (10) with reference to the minimum fill level (30), - generating a warning signal (40) when the minimum fill level (30) is undershot, - monitoring at least one vehicle dynamics parameter (50), - suppressing the output of the warning signal (40) if the at least one driving dynamics vehicle parameter (50) exceeds a predetermined dynamic limit value (52), wherein at least two different driving dynamics vehicle parameters (50) are monitored, wherein a specific dynamic limit value (52) is predetermined for each driving dynamics vehicle parameter (50), and wherein at least one additional combinatorial dynamic limit value (52) is predetermined for each of the at least two driving dynamics vehicle parameters (50). [2] Method according to claim 1, characterized by that when monitoring the fill level (20) of the liquid container (10), only the following two situations are distinguished: - the fill level (20) is at or above the minimum fill level (30) - the fill level (20) is below the minimum fill level (30) [3] Method according to one of the preceding claims, characterized bythat at least one of the following vehicle dynamics parameters (50) is monitored: - Lateral acceleration - Longitudinal acceleration - Vehicle's inclination angle - Engine temperature of the vehicle [4] Method according to one of the preceding claims, characterized by that the suppression of the output of the warning signal (40) continues for a predefined period of time after the predetermined dynamic limit (52) has been undershot by the at least one driving dynamic vehicle parameter (50). [5] Method according to one of the preceding claims, characterized by that the predetermined dynamic limit value (52) can be changed as a function of at least one input value. [6] Method according to one of the preceding claims, characterized by that it is used in at least one of the following liquid containers (10) of a vehicle: - Coolant expansion tank - Engine oil tank - Fuel tank - Windscreen washer tank [7] Method according to one of the preceding claims, characterized by that the step of suppressing the output of the warning signal (40) is carried out by generating and outputting a suppression signal (42). [8] Monitoring device (100) for monitoring the fill level (20) of a liquid container (10) of a vehicle, comprising at least one first sensor device (110) for monitoring the fill level (20) of the liquid container (10) with reference to a minimum fill level (30) and at least one second sensor device (120) for monitoring at least one driving dynamics vehicle parameter (50), characterized by that the monitoring device (100) has a control unit (130), wherein the monitoring device (100) is designed to carry out a method according to one of claims 1 to 7.

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