Improvement in or regarding the monitoring of engine coolant

Abstract

Engine coolant temperature sensor (10), comprising: an earthing line (16) which is arranged to be earthed through the engine coolant (26) in a coolant line (24) in such a way that a warning is triggered when coolant (26) is not present, wherein the earthing line (16) within the temperature sensor (10) is connected exclusively to the housing (18).

Description

[0001] This invention relates to improvements in or concerning the monitoring of engine coolants and, in particular, the monitoring of both the presence and the temperature of this coolant.

[0002] Providing a device for sensing the temperature of engine coolant is common practice in automotive engineering, as the coolant temperature can indicate the temperature inside the engine. To ensure efficient operation, the engine, and therefore the coolant, must be kept within a specified temperature range.

[0003] The sensor will not detect coolant loss because the air temperature will likely remain within the specified range. However, the absence of coolant can have significant adverse consequences for engine operation.

[0004] The present invention was made against this background.

[0005] Publications US 5 708 412 A and CN 2 02 903 362 U each present prior art solutions.

[0006] The object of the present invention is to provide an improved engine coolant temperature sensor, an improved engine system and an improved method for operating an engine system.

[0007] This problem is solved by the subject matter of the independent claims. Preferred embodiments of the present invention are the subject matter of the dependent claims.

[0008] According to the present invention, an engine coolant temperature sensor is provided, comprising an earthing line which is arranged to be earthed by the engine coolant in a coolant line in such a way that a warning is triggered when coolant is not present, wherein the earthing line within the temperature sensor is connected exclusively to the housing.

[0009] The sensor, which combines the functions of an engine coolant temperature sensor and a coolant level sensor, has the ability to protect the entire engine in the event of coolant loss. Integrating this additional function into the temperature sensor reduces cost and complexity compared to using a separate coolant level sensor.

[0010] The sensor may have a metal housing containing a cable designed to allow the sensor to ground itself through the coolant during operation. If the engine experiences a loss of coolant, the sensor will lose this grounding connection previously established by the coolant.

[0011] The warning can be audible or visual. In some designs, both audible and visual warnings can be combined. The purpose of the warning is to draw the driver's attention and ensure that the engine is switched off immediately to allow it to cool down and replenish the coolant. Furthermore, the circumstances leading to the coolant shortage should be investigated to ensure that the problem does not recur.

[0012] If the warning is visual, it can take the form of a light on the dashboard. This positioning is chosen to ensure that the driver notices the light and is notified in order to act immediately.

[0013] The warning can also be linked to the engine control unit (ECU) to force the vehicle into a "limp-home mode." This mode is intended to give the driver a small degree of control to stop the vehicle, allowing them to choose a location to pull over and prevent the driver and other vehicle occupants from being exposed to unnecessary danger due to the vehicle's location at the time of the fault. For example, the vehicle may be configured to allow slow movement over a short distance before the engine is completely shut down.

[0014] The invention will now be described in more detail and with further examples, with reference to the accompanying drawings, in which: Fig. 1 a schematic cross-section through a coolant sensor of the present invention; Fig. 2 is an embodiment of a coolant sensor according to the present invention; Fig. Figure 3 shows the location of the coolant sensor of the present invention within an engine.

[0015] Fig. Figure 1 shows a coolant sensor 10, which includes two temperature sensing cables 12 and 14, and a grounding cable 16. All three cables 12, 14, and 16 are enclosed in a housing 18, which is equipped with a removable metal tip 20. The temperature sensing cables 12 and 14 detect the temperature of fluid adjacent to the metal tip 20 by measuring the resistance through the metal tip 20. Under normal operating conditions, the metal tip 20 is immersed in coolant, and the temperature sensing cables 12 and 14 therefore provide the temperature of the coolant. The temperature data obtained from the sensor 10 is then provided to a vehicle's engine control unit (ECU), which is not shown. Assuming that the detected temperature remains within a predetermined range, the coolant can be considered to be functioning correctly.

[0016] However, if coolant is lost, the temperature sensor will remain functional, and the sensed temperature will be that of the air adjacent to the metal tip 20 of the sensor 10. While this temperature is within the permissible range for coolant, the air cannot adequately cool the engine, and the absence of coolant can cause the engine temperature to exceed the permissible operating range, potentially leading to engine failure.

[0017] The third cable 16 is connected to the metal tip 20 of the sensor to provide a ground connection through the coolant. If coolant is lost, the metal tip 20 can no longer ground, and therefore the ground connection is interrupted. The sensor 10 triggers a warning (not shown) when the ground connection is lost. Therefore, a warning is triggered when the coolant level drops sufficiently that the metal tip 20 of the sensor 10 is no longer immersed in coolant.

[0018] The sensor housing 18 is predominantly made of plastic, with only the tip 10 being metal. This ensures that the sensor 10 does not ground through its mounting location, but is instead forced to ground through the coolant fluid. The size of the metal tip 20 is minimal to minimize the cost and weight of the sensor 10. In some embodiments not shown in the accompanying drawings, a larger proportion of the housing may be made of metal.

[0019] Fig. Figure 2 shows the sensor 10 with the metal tip 20 removed. The plastic housing 18 holds the temperature sensing cables 12, 14 and the grounding cable 16. The grounding cable 16 protrudes in such a way that when the metal tip 20 is engaged with the plastic housing, the grounding cable 16 forms an electrical connection with the metal tip 20. The grounding cable 16 and the plastic tip 20 effectively provide a sensor for the presence of coolant, since the absence of coolant adjacent to the metal tip 20 leads to a loss of the grounding connection.

[0020] The one in the Fig. 1 and Fig. The sensor 10 shown in Figure 2 therefore provides a dual function: identifying the presence of coolant and also providing the temperature reading for the fluid adjacent to the sensor 10. Providing both functions within a single sensor 10 eliminates the need for a separate coolant level sensor. The dual-function sensor 10 has the same encapsulation requirements as a single temperature function sensor and can therefore be retrofitted in a location previously occupied by a temperature sensor. In environments where space is relatively limited, providing the two functions within a single sensor 10 offers efficient space utilization and reduced costs compared to using two separate sensors.

[0021] Fig.Figure 3 shows the sensor 10 in the context of a part of a vehicle engine 22. The engine 22 is shown in cross-section, with the sensor 10 positioned at the highest point in the coolant flow path 24, which is enclosed by a plastic housing 25. The coolant 26 is present throughout the coiled path 24, which leads to the cylinder head 28. The cylinder head 28 is metallic and connected to the vehicle chassis (not shown). The cylinder head 28 therefore provides the grounding point for the sensor 10. The coolant 26 provides the conductor for the grounding connection from the metal tip 20 of the sensor 10 to the cylinder head 28.

[0022] If the coolant level 26 drops so low that it no longer touches the metal tip 20 of the sensor, the grounding connection is interrupted and a warning tone (not shown) sounds.

[0023] A person skilled in the art will recognize that although the invention has been described by way of example with reference to several embodiments, it is not limited to the disclosed embodiments and alternative embodiments can be formed without deviating from the scope of protection of the invention as defined in the pending claims. 10 Engine coolant temperature sensor 12, 14 Temperature sensor cables 16 grounding cables 18 cases 20 metal tips 22 Engine 24 Coolant flow path 25 plastic housings 26 Coolant 28 Cylinder head

Claims

[1] Engine coolant temperature sensor (10), comprising: a ground line (16) configured to ground through the engine coolant (26) in a coolant line (24) such that a warning is triggered when coolant (26) is not present, wherein the ground line (16) within the temperature sensor (10) is connected exclusively to the housing (18). [2] Sensor according to claim 1, wherein the housing (18) is in electrical contact with the ground line (16) and is made of metal. [3] Sensor according to claim 2, further comprising a plurality of temperature measuring wires (12, 14) spaced from the ground line (16). [4] The sensor of claim 2, wherein the alarm is an audible alarm. [5] The sensor of claim 1, wherein the alarm is a visual alarm. [6] Engine system, comprising: an engine coolant temperature sensor (10) comprising a plurality of temperature measuring wires (12, 14) positioned in a housing, a ground line (16) positioned in a housing (18) and spaced from the plurality of temperature measuring wires (12, 14), and a controller that receives signals from the ground line (16) and from the plurality of temperature sensing wires (12, 14) and determines whether a coolant level in a coolant line (24) in which the engine coolant temperature sensor (10) is positioned is below a threshold based on the signals from the ground line (16). [7] The system of claim 6, further comprising a metal tip (20) at least partially enclosing the housing (18). [8] The system of claim 7, wherein the ground wire (16) is in electrical contact with the metal tip (20). [9] The system of claim 6, wherein the controller determines an engine temperature based on the signals from the plurality of temperature sensing wires (12, 14). [10] A method for operating an engine system, comprising: Determining an engine temperature based on signals from a plurality of temperature measuring wires (12, 14) in an engine coolant temperature sensor (10); and Determining whether the engine coolant temperature sensor (10) is grounded based on signals from a ground line (16) in the engine coolant temperature sensor (10), wherein the ground line (16) is not connected to the plurality of temperature sensing wires (12, 14).

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