Abstract: The present invention is directed to a portable power unit for use with various power tools.

Abstract: An electronic ignition system for a gas burner is battery operated. The battery voltage is applied through a DC-DC chopper to a step-up transformer to charge a capacitor which provides the ignition spark. The step-up transformer has a significant leakage reactance in order to limit current flow from the battery during initial charging of the capacitor. A tank circuit at the input of the transformer returns magnetizing current resulting from the leakage reactance to the primary in succeeding cycles. An SCR in the output circuit is gated through a voltage divider which senses current flow through a flame. Once the flame is sensed, further sparks are precluded. The same flame sensor enables a thermopile driven main valve actuating circuit. A safety valve in series with the main gas valve responds to a control pressure thermostatically applied through a diaphragm. The valve closes after a predetermined delay determined by a time delay orifice if the pilot gas is not ignited.

Abstract: An electronic ignition system for a gas burner is battery operated. The battery voltage is applied through a DC-DC chopper to a step-up transformer to charge a capacitor which provides the ignition spark. The step-up transformer has a significant leakage reactance in order to limit current flow from the battery during initial charging of the capacitor. A tank circuit at the input of the transformer returns magnetizing current resulting from the leakage reactance to the primary in succeeding cycles. An SCR in the output circuit is gated through a voltage divider which senses current flow through a flame. Once the flame is sensed, further sparks are precluded. The same flame sensor enables a thermopile driven main valve actuating circuit. A safety valve in series with the main gas valve responds to a control pressure thermostatically applied through a diaphragm. The valve closes after a predetermined delay determined by a time delay orifice if the pilot gas is not ignited.

Abstract: In a force measuring platform, a top plate 12 is supported on tubular load cells 16. The load cells have strain gages to measure the strain due to the horizontal shear forces. The "shear" strain gages also measure moments about the Z axis when properly placed in a bridge circuit. Strain gages mounted to measure vertical strain indicate vertical forces and moments about horizontal axes.

Abstract: The safety valve contains a resilient gland to be held between a valve seat and a valve member and is secured to the valve member by a sleeve surrounding the end of the valve member adjacent to the valve seat. The sleeve is movable relative to the valve member through a limited axial distance and a gap exists between said valve member and said sleeve.

Abstract: A high efficiency gas fired residential water heater includes an insulated, plastic-lined storage tank. The water in the tank is heated by an external heat exchanger which defines a water-walled combustion chamber. The fuel gas and combustion air burned in the chamber are premixed to a near stoichiometric mixture without the use of a blower. Under the force of line pressure or less, the fuel gas is accelerated into an aspirator/mixer which premixes an amount of air sufficient for complete combustion of the fuel gas. The water-walled combustion chamber is particularly suited for substantial recovery of the heat of a pilot flame. The pilot products of combustion heat water at the upper end of the combustion chamber without causing significant convective flow throughout the heat exchanger.

Abstract: A burner assembly provides for 100% premixing of fuel and air by drawing the air into at least one high velocity stream of fuel without power assist. Specifically, the nozzle assembly for injecting the fuel into a throat comprises a plurality of nozzles in a generally circular array. Preferably, swirl is imparted to the air/fuel mixture by angling the nozzles. The diffuser comprises a conical primary diffuser followed by a cusp diffuser.

Abstract: In a water heating system, vapor in the products of combustion gases is condensed in a secondary heat exchanger positioned in a housing with the primary heat exchanger and combustion chamber. The two heat exchangers are coaxial coils with the secondary coil positioned below the primary. Gases flow radially through the primary coil and then axially through the secondary coil at an increased velocity. The gases are then used to pre-heat a gas/air mixture in a third heat exchanger within the secondary heat exchanger. The pre-heated gas/air mixture is burned in a burner within the primary heat exchanger and the gas products are drawn through the exchangers by a blower. A water storage tank is designed to enhance stratification of hot water over cooler water. The cooler water is used to condense vapor in the secondary heat exchanger.

Abstract: A force measuring apparatus includes a platform construction on which forces may be exerted, as for example, by an individual stepping upon a top plate of the platform construction. Apparatus of this nature is commonly referred to in the art as a "Biomechanics Platform", and may include a bottom plate, a top plate deformable by forces exerted thereon and a plurality of load cell members arranged to yieldably support the top plate in spaced relation to the bottom plate. The load cells are constructed with strain ring means having strain gage elements suitably supported thereon, and the cells further include composite anchoring means for connecting the top plate with strain rings of respective load cells in a unique manner. Each of the composite anchoring means includes a compliant or elastic member which is arranged to transmit, at any given time, an entire load exerted between the top plate and its respective load cell.

Abstract: A high efficiency gas fired residential water heater includes an insulated, plastic-lined storage tank. The water in the tank is heated by an external heat exchanger which defines a water-walled combustion chamber. The fuel gas and combustion air burned in the chamber are premixed to a near stoichiometric mixture without the use of a blower. Under the force of line pressure or less, the fuel gas is accelerated into an aspirator/mixer which premixes an amount of air sufficient for complete combustion of the fuel gas. The water-walled combustion chamber is particularly suited for substantial recovery of the heat of a pilot flame. The pilot products of combustion heat water at the upper end of the combustion chamber without causing significant convective flow throughout the heat exchanger.

Abstract: A random vibration generator includes a hollow tabletop for supporting equipment to be subjected to vibration, and a sinusoidal reaction-type vibration machine connected to the tabletop to produce a sinusoidal vibration of adjustable frequency and amplitude. The hollow tabletop is horizontally divided into four sections, each containing a number of projectiles such as heavy balls which roll and bounce about within the compartments in the tabletop, impacting with the floor and ceiling of the compartment and with each other in a random fashion to produce random shocks over a wide band of frequency and amplitude, and subject the equipment to every possible vibration failure mode that might occur in nature.

Abstract: In a water heating system, vapor in the products of combustion gases is condensed in a secondary heat exchanger positioned in a housing with the primary heat exchanger and combustion chamber. The two heat exchangers are coaxial coils with the secondary coil positioned below the primary. Gases flow radially through the primary coil and then axially through the secondary coil at an increased velocity. The gases are then used to pre-heat a gas/air mixture in a third heat exchanger within the secondary heat exchanger. The pre-heated gas/air mixture is burned in a burner within the primary heat exchanger and the gas products are drawn through the exchangers by a blower. A water storage tank is designed to enhance stratification of hot water over cooler water. The cooler water is used to condense vapor in the secondary heat exchanger.