Abstract: Provided are apparatus, including electronic thermostats, for detecting temperatures and elapsed times and, in response to those temperatures and elapsed times, controlling the opening or closing of an electric circuit.

Abstract: Apparatus for monitoring a refrigerant state in a refrigeration system includes a charge sensor and a controller. The sensor is positioned adjacent to the outlet of an evaporator. The sensor produces a voltage output signal in response to an input signal from the controller. The controller compares the output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state. The sensor is preferably a self-heated thermistor positioned adjacent to flow exiting the evaporator through the outlet. The controller preferably compares the output signal to a set point at preset intervals and computes an average for a predetermined time duration. This helps to avoid false readings due to transitory conditions. The apparatus may be used in various types of refrigeration systems but is contemplated to be used primarily in mobile air conditioning systems in order to detect a reduced refrigerant charge in such systems.

Abstract: A heater circuit in a vehicle engine cooling and passenger compartment heating system comprises a control valve (26), and a supply line (22) and a return line (24) both of which are separate from the radiator circuit of the system. A bypass passageway (48) extends between the supply line (22) upstream of the valve (26) and the return line (24) downstream of the valve (26). A bypass valve normally closes the passageway (48) and opens in response to a pressure differential between the supply line (22) and return line (24) exceeding a predetermined magnitude. The passageway (48) has first and second detachably connected portions that communicate with the supply and return lines (22, 24) via radial openings (44, 46). A spring (72) abuts a shoulder (54) in the second portion and a valve element (62) that seats against a flat surface surrounding the radial opening (44) in the supply line (22). The element (62) has laterally extending guide teeth (68) and a rear reduced diameter lug (70) engaged by the spring (72).

Abstract: A T-block fitting (22) has an integral molded plastic body (24) including a stem (28) with a radial shoulder (26) and a radial flange (30) on opposite ends. An externally threaded split nut (40, 42) has a major portion (40) with a circumferential extent greater than 180.degree., and a minor portion (42). Complementary chordal mating surfaces (46, 62) are formed on the major and minor portions (40, 42). A semicylindrical projection (64) extends perpendicularly from each mating surface (62) and is received into a corresponding recess (48) in the abutting mating surface (46). A slot (50) extends along each mating surface (46) on the head portion (54) of the major portion (40). The slot (50) opens onto an outer surface of the head portion (54) and terminates in an inner enlarged diameter portion (52). A corresponding projection (66) with an enlarged inner end (68) is formed on each mating surface (62 ).

Abstract: The conical tip of a load applying member (42) acts against one side (136) of a movable plate (120). A spring (84) urges the conical tip of a biasing member (88) against the other side (138). In response to a relatively small movement of member (42) against plate (120), plate (120) pivots about a first axis a.sub.1 to depress the operator (102) of a first snap-action switch (98). In response to a relatively large movement of member (42), plate (120) pivots away from contact with operator (102), first about auxiliary axis a.sub.4 and then about third axis a.sub.3. In response to an intermediate movement, plate (120) pivots to depress the operator (103) of a second snap-action switch (99), first about second axis a.sub.2 and then about auxiliary axis a.sub.4. Axis a.sub.4 is defined by first and second fulcrums (71, 134). Axis a.sub.2 is defined by second fulcrum (134 ) and operator (102); axis a.sub.3 is defined by first fulcrum (71) and operator (103). Axis a.sub.

Abstract: A housing (28) has parallel passageways (30). Each passageway (30) has an inlet port (34) and an outlet port (32). A valve stem (26) with a head (36) reciprocates in each passageway (30) to control the outlet port (32). A flat plate (22) rotates perpendicularly to the stems (26) and has flat surface portions (48) and cavities (46). The positioning of portions (48) and cavities (46) is programmed to bring one of them into alignment with each stem (26) when plate (22) is in any one of a number of predetermined positions. When a portion (48) is moved into alignment, it bears against the head (36) and moves the stem (26) inwardly against a spring (38) into a second position. When a cavity (46) is moved into alignment, the stem (26) is urged into its first position by spring (38) and its head (36) extends into the cavity ( 46).

Abstract: A desired temperature within the passenger compartment (10) of a motor vehicle is selected by occupant movement of a control lever (80) for a variable resistor (VR2). The temperature of conditioning air being supplied to the compartment is measured by a thermister (72). The two temperatures are electronically compared. If the measured temperature is higher than the selected temperature, a solenoid (62) is energized which moves a control valve (48) in a position allowing passage of pressurized air into an air cylinder (26). The air cylinder (26) functions to close a valve (22) in a water line (18, 20) which extends from the engine cooling system to a heat exchanger (24) located within the conditioning air duct (12). When the temperature of the conditioning air falls below the selected temperature level, the solenoid (62) is de-energized and a spring (54) moves the control valve (58) into a position in which it blocks flow of compressed air to the air cylinder (26) and vents the air cylinder to the atmosphere.

Abstract: A conductive member of plate form is supported on a spring biased member into a static postion of contact at a first corner with a support surface and at a second adjacent corner with a first contact member. A load applying member makes contact with the conductive member on the side thereof opposite from the spring biased support. A low rising pressure acting through the load applying member swings the conductive member in position about a first axis defined by its locations of contact with the support surface and the first contact member into a position in which it also contacts a second contact member and completes a conductive path between the two contact members. An intermediate rising pressure signal causes the conductive member to swing in position about a second axis defined by its locations of contact with the two contact members and against the operator of a micro-switch.