Measuring and testing – Liquid level or depth gauge
Reexamination Certificate
1999-09-14
2001-08-14
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Reexamination Certificate
active
06272923
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a cooling system for an internal combustion system. More particularly this invention concerns a system for determining the fill level of such an engine cooling system.
BACKGROUND OF THE INVENTION
In a standard motor-vehicle cooling system sensors are provided for determining the fill level of the liquid. Such sensors can be of the simple float or pressure type and serve mainly to ascertain if the fill level dips below a certain threshold. This information is used to indicate to the driver that the coolant supply should be checked.
Such a system is invariably of the simple on/off type, that is it merely indicates whether or not the fill level is above or below a certain threshold. It gives no indication of how much above or below, that is does not provide an output of relative fill level. In addition the sensors of such systems are notoriously unreliable. Most work poorly in a sometimes violently moving bath of water containing various chemically active substances and have a short service life.
In another known system described in German patent document 41 16 496 a device detects overloading of the coolant pump and alters the timing or fuel feed of the engine so that it runs cooler. Thus this arrangement provides a sort of emergency operation mode, but in no way supplies the user of the engine with information about how much coolant is in the system.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved system for determining the fill level of the liquid in a cooling system.
Another object is the provision of such an improved system for determining the fill level of the liquid in a cooling system which overcomes the above-given disadvantages, that is which supplies an output indicating relative fill level.
A further object is to provide an improved apparatus for doing this which is very simple and reliable and which can be incorporated at minimal cost into a motor vehicle.
SUMMARY OF THE INVENTION
A cooling system of a motor-vehicle internal-combustion engine has a pump driven by a current-consuming electrical motor. The liquid fill level of a this system is determined according to the invention by continuously and concurrently monitoring current consumption of the electrical motor and generating an output corresponding thereto. The output is continuously compared with at least one threshold and a difference between the output and the threshold is established as the fill level of the cooling system.
Monitoring the current consumption of the pump's motor is extremely easy and can be done at very little cost, it merely being necessary to set up an ammeter, that is a voltage meter measuring current drop across a resistor, in the line to the motor driving the water pump. The need for actual sensors in the cooling system is avoided, which means that the liquid level can be monitored more effectively with equipment that is simpler, cheaper, and more reliable. What is more the system is capable of determining the coolant level somewhat analogously, or at least at several different levels which is quite useful. The system is so simple and inexpensive that it can even be used for redundancy's sake in addition to the known system with a sensor in the reservoir and a simple warning lamp for low coolant.
In accordance with the invention an alarm signal is emitted when the output drops below the threshold. When the output is compared with two separate such thresholds one of which is lower than the other, the signal is emitted when the output drops below the lower threshold. It is also within the scope of this invention to emit the alarm signal when the output drops to a level somewhat above the threshold, the difference being determined electronically by the control system serving as comparator.
In practice it has been surprising learned that there are three distinct levels of current consumption for the electrical motor of a water pump in a cooling system. When the system is completely full and the pump is only moving liquid, the load is greatest and current consumption is at its maximum. When the level is somewhat low so that there is cavitation and the pump periodically is pushing gas in addition to liquid, the level is at an intermediate level. Finally when the system is dry the pump runs freely, moving no significant load, so that consumption it at a minimum. In fact the intermediate cavitation level is not represented by a sudden change but is a gradual change in current consumption, so the system can even gauge intermediate fill levels.
According to the invention the sensor can be incorporated in the motor. It can be an ammeter or hall-effect sensor.
REFERENCES:
patent: 3763836 (1973-10-01), Guehr
patent: 4786866 (1988-11-01), Yabe et al.
patent: 4913625 (1990-04-01), Gerlowski
patent: 7037473 (1971-02-01), None
patent: 2131271 (1972-01-01), None
patent: 3825500 (1990-02-01), None
patent: 4116496 (1991-12-01), None
patent: 42 121971 (1992-11-01), None
patent: 0893582 (1999-01-01), None
patent: 07026953 (1995-01-01), None
Dubno Herbert
Pierburg Aktiengesellschaft
Wilford Andrew
Williams Hezron
Worth Willie Morris
LandOfFree
Determining fill level of engine cooling system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Determining fill level of engine cooling system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Determining fill level of engine cooling system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2551377