Low fluid level warning system

A low fluid level warning system for use with a reservoir to provide a warning when the level of fluid in the reservoir is below a predetermined level, the warning system comprising:

• first conduit means having an opening positioned near the bottom inner surface of the reservoir at a first level thereof and below said predetermined level for receiving fluid therefrom;
• selectively activated circulating means having activated and deactivated states, and connected to the first conduit means for pumping fluid from the reservoir upwardly through the first conduit means when in the activated state;
• pressure chamber means connected to the circulating means to receive pressurized fluid from said circulating means;
• pressure-sensing means connected to the pressure chamber means for sensing the pressure therein;
• and
• indicator means having activated and deactivated states and connected to the pressure-sensing means for providing an indication of the pressure in the pressure chamber means, the indicator means being in the deactivated state when the pressure in the pressure chamber means is above a predetermined pressure and the indicator means being in the activated state when the pressure in the pressure chamber means is below the predetermined pressure;
• said indicator means being deactivated substantially immediately upon selectively activating the circulation means after a period of deactivation of the circulating means when the level of fluid in the reservoir is above the predetermined level;
• the improvement which comprises:
• the warning system further comprises means in fluid communication with the pressure chamber means and the reservoir to maintain the pressure in the pressure chamber means below said predetermined pressure and to thereby maintain the indicator means in an activated state for a relatively short predetermined time upon selectively activating the circulating means and following deactivation of the circulation means when the level of fluid in the reservoir is above the first level but below the predetermined level;
• whereby said indicator means is in said activated state only for said relatively short predetermined time following selective activation of the circulating means subsequent to a period of deactivation of the circulating means when the level of fluid is below the predetermined level and above the first level to give an indication of a low-fluid condition.

A low oil level warning system for use with an engine oil reservoir to provide a warning when the level of oil in the reservoir is below a predetermined level, the warning system comprising:

• first conduit means having an opening positioned near the bottom inner surface of the reservoir at a first level thereof and below the predetermined level for receiving oil therefrom;
• an engine activated circulating means driven by the engine and connected to the first conduit means for pumping oil from the reservoir upwardly through the first conduit means when the engine is operated;
• pressure chamber means connected to the circulating means to receive pressurized oil from the circulating means;
• pressure-sensing means connected to the pressure chamber for sensing the pressure therein;
• and
• indicator means having activated and deactivated states and connected to the pressure-sensing means for providing an indication of the pressure in the pressure chamber means, the indicator means being in the deactivated state when the pressure in the pressure chamber means is above a predetermined pressure and the indicator means being in the activated state when the pressure in the pressure chamber means is below the predetermined pressure;
• said indicator means being deactivated in a short first time period upon engine start-up when the level of oil in the reservoir is above the predetermined level;
• the improvement which comprises:
• the warning system further comprises means for delaying deactivation of the indicator means upon engine start-up for a second time period, longer than the first time period, when the level of oil in the reservoir is above the first level but below the predetermined level;
• whereby upon engine start-up, said indicator means is activated for said first time period when the oil in the reservoir is above the predetermined level and is activated for said second time period before deactivation when the oil in the reservoir is below the predetermined level but above the first level, thereby giving an indication of a low oil condition.