Sump pump activation switch

This application claims priority from U.S. Provisional Patent Application Ser. No. 60/937,599 filed Jun. 27, 2007, and incorporated herein in its entirety by reference.

The disclosed device relates to fluid activated switches for electrical devices. More particularly, the disclosed device relates to a switch for a sump pump having a hose mount that imparts a ground reference to the water or fluid while concurrently insuring the user self-installs the device at a proper level in the water to ensure proper operation.

Sump pumps are commonly employed on boats and ships to ensure that the bilge tanks do not overflow and are promptly and automatically emptied when needed. Another common function of a sump pump is to protect a basement from flooding.

In such installations, the pump is conventionally activated when water or other fluid reaches a certain level in the sump tank or bilge. Once activated by a switch the pump pumps out the excess water or fluid in the tank.

Many switches have been employed over the many years of sump pumps. One type of switch is a float switch is the part of the sump pump that activates the pump when water reaches a certain threshold. Essentially, a float on the end of a control rod rises and falls with water levels. At some lever in the rise, the switch activates the pump to remove fluid. Once the float switch settles to a new level as water is evacuated, it will turn off the pump. Due to harsh operating conditions, especially in a marine environment, a float switch is usually the first part of a sump pump to break, so it is recommended to choose a sump pump whose float switch is easily replaceable.

Another type of pump switch is the diaphragm switch which is engaged to the body of the pump which is immersed under water. A membrane in the diaphragm switch is sensitive to water pressure. As the water level rises, the water pressure increases and the diaphragm becomes concave, thereby activating the switch to turn on the sump pump. When the water level drops, the switch turns off. Such switches in a marine environment with oil and debris in the water are subject to problems and mechanical failure. Further the rocking of a boat can cause the water in the tank to push on the diaphragm and activate the pump in a condition that is too low for the pump to operate.

In the highly dynamic application such as the bilge of a small boat, as the boat bounces from wave to wave, a pivoting float will cause the switch to close many times per minute even without water in the bilge. This needlessly consumes the switch contact so that the system has a relatively short life. Further, a diaphragm switch can suffer the same fate due to moving fluid in the bilge from the moving and rocking boat.

A more modern switch employs electronic switching using sensors to ascertain the presence of water or fluid sufficient to require pump activation. Generally, such electronic devices employ a plurality of electrical contacts with the fluid with one to impart an electrical signal or other aspect to the fluid which is picked up by the other sensor. Or, the second sensor may negate the signal imparted if fluid is present and fail to do so when it is not. Many such devices use some type of electronic sensing that employs a reference to battery ground to the signal received to ascertain the presence of water and turn on the pump. The sensor continually sensing the fluid for an electronic property such as voltage, current, inductance impedance, resistance, or one or a combination of such electronic properties, will generally be under the fluid when activating the pump, and will turn the pump off if not under the fluid. The monitoring sensor is seeking the electronic property imparted to the fluid by a second component which must always be below fluid level for the device to work. It is extremely important that the plurality of electronic contacts for such devices to be properly immersed in the fluid to be pumped. If one of the electronic contacts is mounted too high and out of the fluid, the electronic switch cannot function to turn on the pump since no signal is transmitted or received to cause it.

However, since most such pump switches are user-installed, and because users fail to read directions, or view the electronic contacts and assume the wrong mounting scheme, many electronic switches for sump pumps fail or perform poorly.

As such, there exists an unmet need for a sump pump switch which will endure the harsh marine environment and moving fluid in a bilge or other tank, to properly activate a sump pump. Such a device should employ electronic communicating contacts with the fluid which provide and receive a signal through the fluid which ascertains the presence or absence of the fluid. Such a device should impart a ground reference to the fluid such that it can be accurately measured should the bilge be poorly grounded. Finally, and of major importance, such a device, being generally user-replaced, should provide a mounting configuration which ensures that the sensor is properly submersed in the fluid it monitors and thereby avoids confusion or assumption by the user as to proper mounting.

The disclosed device is a float switch replacement for a marine bilge sump pump or other sump pump which is immersed in a fluid such as water in a storage tank such as a bilge or sump tank.

The device employs an electronic circuit to constantly sample the fluid for an electronic property using a first sensor that communicates through the casing with the fluid. A second contact is employed to affect the electronic property by proving a ground to the fluid such that the electronic property can ascertain the presence of fluid and turn on the pump.

In the current device, the electric property is a capacitance load of the bilge water that is monitored. An analog inverter CMOS chip oscillates at approximately 10,000 hertz. A frequency is generated into the fluid which is referenced at the water sensor. Through the sensor, a logic circuit looks for a change in frequency to activate the pump. Water covering a metallic component will change the frequency sufficiently to flip the logic circuit to turn on power to the pump, however ungrounded tanks such as fiberglass tanks or those on fiberglass boats, and improperly mounted sensor components communicating with the fluid, will cause the switch to malfunction. A ground communicating with the battery providing power to the logic circuit, submersed in the fluid, enhances the performance of the logic circuit by providing a better reference to ground through the fluid.

This problem with improperly mounted sensors and poor ground reference has been exacerbated in prior manufactured devices which have employed a casing wherein the two or more metal electronic monitor components communicating through the casing, have to be properly oriented in the fluid. Users installing such devices frequently do not read the directions and install them incorrectly. Most such devices employ screw apertures to mount the device in the tank and invite improper installation by installers who assume one or both metal components must be below water level.

Most sump pumps employ a fluid intake under a bottom or very low side surface for intake of fluid. A pump inside the pump casing exhausts fluid through an exhaust hose which is routed to drain the bilge or tank. The hose is conventionally engaged to a hose bib on the pump with a hose clamp. This hose clamp and bib are conventionally located just above the intake by design since the intake is conventionally located as low as possible in the tank in which the pump is placed.

The novel casing provided with the device employs two components which enhance performance of the internal electronic switch. First, since the hose bib on sump pumps is conventionally located above the lower water intake which is the lowest point the water will reach, providing a mounting member that extends from the casing to mount the device to the hose bib, inherently mounts the casing, and sensing and monitoring component, just above the lowest point the water can reach. This is exactly the correct placement for the sensor and by providing a mounting member with a curved lower surface, adapted to engage under the hose clamp, the user inherently will mount the casing correctly even if they fail to read the installation directions which is a frequent occurrence.

Additionally, the mounting member is connected to the battery ground. By mounting it to the mounting member which will encounter the fluid, a very good ground reference is imparted to the fluid before or at the same time the fluid reaches the sensing component looking for an electronic property in the fluid to ascertain fluid levels at or above the sensing component to activate the switch to turn on the pump. On fiberglass boats and tanks, this properly located reference to ground greatly enhances switch performance. On older boats corroded tanks, an equal gain in performance is provided by this novel inherently properly positioned grounding component.

It is thus an object of this invention to provide a switch for a sump pump which has a member extending from the casing which provides a curved surface to engage under a hose clamp conventionally employed on hoses engaged to a submerged sump pump.