Abstract: It is an object to provide a method of adjusting a pressure sensor, in which adjustment of a diaphragm portion and adjustment of an amplification circuit connected to the diaphragm portion are simplified. A flexible circuit board having the amplification circuit mounted thereon is connected to a diaphragm member having the diaphragm portion formed with gauge resistances, and offset, span and temperature-compensating adjustment resistances, and adjustment of the adjustment resistances formed on the diaphragm member is performed in this state. The adjustment on the side of the diaphragm member including the amplification circuit accommodates adjustment deviation on the amplification circuit, and hence adjustment of the whole pressure sensor can be achieved by a single adjustment process. The adjustment process thus simplified can reduce manufacturing costs.

Abstract: The object of the present invention is to provide a three-way switching valve having a valve mechanism compact in size, and capable of changing a flow of a high-pressure fluid, without internal leakage of the fluid. A compact pilot-operated three-way switching valve changes a flow of a fluid introduced into an inlet port such that the fluid is caused to flow into a first outlet port or a second outlet port. Pressures in pressure-regulating chambers above pistons are selectively guided into a passage by a pilot valve having a pilot valve element, plugs including respective valve seats, and a spring. The passage leads one of the pressures to the first outlet port or the second outlet port via a check valve having valve, and a valve element. The check valve causes a very small amount of fluid permitted to flow so as to keep main valves open and closed, respectively, to flow to the downstream side of an open one of the main valves, whereby internal leakage of fluid is prevented.

Abstract: To provide a refrigeration cycle which is capable of reducing power consumption while solving the problems of hunting and oil circulation. The refrigeration cycle is formed by combining an expansion valve that controls the flow rate of refrigerant supplied to an evaporator such that refrigerant at the outlet of the evaporator always maintains a predetermined level of superheat, in normal times, and is equipped with a minimum flow rate-securing device capable of allowing the refrigerant to flow at a predetermined minimum flow rate when the flow rate is most restricted, with a variable displacement compressor.

Abstract: To provide a constant differential pressure valve which is compact in size and can be realized at low cost. In the constant differential pressure valve according to the present invention, a pipe forming a body thereof not only accommodates internal structures, such as a differential pressure control mechanism, a movable core, and a fixed core, but also serves as part of piping of a refrigeration cycle. Further, a solenoid section including a solenoid coil is disposed outside the pipe in a manner surrounding the same. Therefore, substantial integration of the differential pressure control mechanism into the piping of the refrigeration cycle can be achieved, which makes the entire constant differential pressure valve very simple in construction. As a result, reduction of the size of the constant differential pressure valve and resultant reduction of material costs and manufacturing costs can be achieved, which makes it possible to achieve low costs of the constant differential pressure valve.

Abstract: To provide a small-sized solenoid-driven flow-regulating expansion valve which can be realized at low cost. In a flow-regulating expansion valve according to the present invention, a pipe forming a body thereof not only accommodates internal structures, such as a flow-regulating mechanism, a movable core, and a fixed core, but also serves as a part of piping of a refrigeration cycle. Further, a solenoid section including a solenoid coil is disposed outside the pipe in a manner surrounding the same. Therefore, substantial integration of the flow-regulating mechanism in the piping of the refrigeration cycle can be achieved, which makes the entire flow-regulating expansion valve very simple in construction. As a result, reduction of the size of the flow-regulating expansion valve and resultant reduction of material costs and manufacturing costs can be achieved, which makes it possible to achieve low costs of the flow-regulating expansion valve.

Abstract: The object of the present invention is to provide a proportional valve which does not open or close by itself and is free of internal leakage. A valve element is formed integrally with a piston having a cross-sectional area equal to that of a valve hole constituting a valve seat, and a diaphragm having an outer peripheral portion secured to a body by a holder is disposed in contact with a pressure-receiving end face of the piston. The diaphragm is mounted in a displaced state such that when the valve element is seated on the valve seat, the pressure receiving area of the diaphragm is at a maximum and is equal to that of the valve element. Change in the pressure receiving area of the valve element corresponding to the lift amount thereof is canceled out by change in the pressure receiving area of the diaphragm corresponding to the amount of displacement thereof, thus preventing the valve from opening or closing by itself due to the difference between the pressure receiving areas.

Abstract: To provide an expansion device that is configured compact in size and capable of effectively preventing an abnormal rise in pressure within the expansion device caused by the differential pressure across the expansion device. An expansion device according to the present invention cancels part of refrigerant pressure by a pressure-canceling structure. More specifically, by the amount of pressure received by a valve-closing pressure-receiving surface, the elastic force required of a spring can be reduced. As a result, a small-sized spring can be employed as the spring, and the entire expansion device can be made compact in construction. Further, when the differential pressure across the expansion device has become equal to or higher than a predetermined value, a relief mechanism enables refrigerant flowing in from the upstream side to escape into a passage other than a refrigerant passage through a valve element.

Abstract: To provide a capacity control valve for a variable displacement compressor of a Pd-Ps differential pressure-controlled type, which suppresses overshooting of the differential pressure between the discharge pressure Pd and the suction pressure Ps which can occur when the differential pressure is changed in response to a stepwise change in the solenoid current. The capacity control valve includes a valve section having a Pd-Pc valve for control of the flow rate of refrigerant flowing from a discharge chamber to a crankcase and a Pc-Ps valve for control of the flow rate of refrigerant flowing from the crankcase to a suction chamber operating in a manner interlocked with the Pd-Pc valve.

Abstract: To provide a four-way solenoid valve having a three-way solenoid valve of which non-concentricity between a valve element and a valve hole is small, if any. A core of a three-way solenoid is integrally formed with a refrigerant passage extending axially therethrough, an annular projection forming a valve seat, and a guide for guiding reciprocating motion of a needle forming a valve element. A plug closing a cylinder of a body to define the pressure control chamber is also integrally formed with a valve seat and a guide for guiding reciprocating motion of a needle forming a valve element associated with the valve seat. This causes the needles to be seated on the valve seats associated therewith in respective states guided by the guides substantially concentric with the valve holes, which makes it possible to impart sufficient sealing properties to the valve portions when each valve is closed.

Abstract: To provide an expansion valve having a low-pressure passage that is bent at right angles therein, which is reduced in untoward noise and noise of the flow of refrigerant generated when the refrigerant passes through the low-pressure passage. In an intersecting portion of a low-pressure passage, the axis of a port for introducing refrigerant returned from an evaporator, and the axis of a port for guiding out refrigerant having passed through a body block to a compressor are orthogonal to each other. A hole is formed in the body block in a direction of insertion of a shaft that transmits a driving force from a power element to a valve element, and a holder for holding the shaft.

Abstract: The object of the present invention is to provide a refrigeration cycle for an automotive air conditioner, which is reduced in costs and uses an ejector. A variable displacement compressor driven by an engine for driving an automotive vehicle is used as a compressor, and the capacity of the compressor is controlled by a capacity control valve such that the differential pressure between discharge pressure and suction pressure of refrigerant becomes equal to a predetermined differential pressure determined by an external signal. Pressure substantially equal to pressure applied across the compressor is applied across the ejector, and therefore to control the differential pressure across the compressor is to control the differential pressure across the ejector. A differential pressure valve disposed between a gas-liquid separator and an evaporator is set to a differential pressure approximately proportional to the differential pressure across the ejector.

Abstract: The object of the present invention is to provide a three-way valve reduced in the number of component parts and man-hours for assembling the component parts. A pressure chamber of a piston for urging a first main valve in a valve-closing direction by a spring, and a pressure chamber of a piston for urging a second main valve in a valve-opening direction against the urging force of a spring are connected to a medium-pressure port B via a pilot valve and a pressure passage. When the pilot valve is open, the pressure in the pressure chambers into which high-pressure fluid is introduced from a high-pressure port A via an orifice is permitted to escape to the medium-pressure port B, whereby the piston is pushed upward by the high pressure to open the first main valve, and a plug is urged by the spring to close the second main valve.

Abstract: A four-way switching valve free from leakage of a refrigerant is disclosed. The valve includes two three-way switching valves arranged side by side, each having a pressure-regulating chamber, a piston, and a plug coaxially arranged. One of the pressure-regulating chambers selectively communicates with a low-pressure chamber or a high-pressure chamber via a three-way solenoid valve. The other pressure-regulating chamber communicates with another chamber in which the pressure increases or decreases as the pressure within one of the pressure-regulating chambers decreases or increases. As a result, refrigerant leakage is prevented, in turn preventing degradation of the refrigerating power of a system.

Abstract: The object of the present invention is to provide a simple-construction four-way switching valve which is simple in construction and excellent in sealability, performs switching of the operation mode without producing unusual noise, and is reduced in the number of manufacturing steps through elimination of externally-mounted parts for pressure passages. Main valves having a poppet valve structure constitute a three way switching valve which is operated by a pilot valve, for switching the high-pressure refrigerant introduced into the port T1 to the port T2 or to the port T3, and main valves which have a poppet valve structure and are switched by the differential pressure between the ports T2 and T3 constitute a low-pressure three-way switching valve. This makes it possible to improve the sealability, prevent unusual noise from being generated during switching of the operation mode, and simplify the construction.

Abstract: The object of the present invention is to provide a method of controlling a refrigeration cycle such that maximum refrigerating capacity can be educed when the refrigeration cycle is started, the driving torque of a variable displacement compressor can be reduced when an automotive vehicle performs standing start or acceleration, and the refrigeration cycle can be operated with the maximum efficiency in a steady operating condition.

Abstract: The object of the present invention is to provide a control valve for a variable displacement compressor, which is used for controlling differential pressure between discharge pressure and suction pressure such that the differential pressure becomes equal to differential pressure set by duty ratio control, and improved in characteristics thereof when it is in the vicinity of the valve-closing position. A valve section for controlling the flow rate of refrigerant at discharge pressure Pd to thereby supply refrigerant at pressure Pc to a crankcase is implemented by a spool valve structures. A spool valve element and a shaft arranged coaxially with each other are configured such that the spool valve element and the shaft oppositely receive the discharge pressure Pd and the suction pressure Ps, respectively. The differential pressure between, the discharge pressure Pd and suction pressure Ps, which is to be controlled, is set by a pulse current supplied to a solenoid section which is duty ratio controlled.

Abstract: To provide a small-sized and low-cost proportional solenoid valve which is capable of controlling a bidirectional fluid flow. A core is fixed in a pipe, and a hollow shaft having an extreme end thereof closed by a valve seat and a portion adjacent thereto formed with valve holes is fixed in the core. Within the pipe, there are arranged a hollow cylindrical valve element axially movable using the shaft as a guide and urged in a direction away from the core by a spring, for opening and closing the valve holes, and a plunger, while outside the pipe, there is arranged a solenoid coil. The proportional solenoid valve has a body formed by the pipe, and the component parts for opening and closing the valve are arranged within the pipe, so that it is possible to reduce the size of the proportional solenoid valve, the number of component parts, and machining costs and material costs, which contributes to reduction of costs of the valve.

Abstract: The object of the present invention is to provide a switching valve capable of increasing the opening stroke of a valve operated by a differential pressure while saving space, thereby reducing pressure loss. A first valve is disposed between an inlet port and a first outlet port. A pilot valve is provided between a back pressure chamber for a movable plug that holds a valve sheet disposed in a manner opposed to a valve seat, and the first outlet port, such that the first valve is operated by a solenoid. A second valve is arranged between the inlet port and a second outlet port. A back pressure chamber for a movable plug that holds a valve sheet disposed in a manner opposed to a valve seat and the first outlet port are communicated with each other. The second valve is opened by the differential pressure generated by closing of the first valve, and when the first valve is opened, the second valve is closed by the spring since the differential pressure is reduced to zero.

Abstract: The object of the present invention is to provide a method of operating a refrigeration cycle which is capable of preventing oil from staying in an evaporator and ensures high coefficient of performance as well as sufficient circulation of oil. An electronic expansion valve is controlled such that during normal operation, refrigerant is always in a superheated state at the outlet of an evaporator, and the refrigerant is periodically forced to have negative superheat for a predetermined time by a superheat control device. Thus, during normal operation, the refrigerant sucked into a variable displacement compressor always has superheat, whereby the refrigeration cycle can operate with high coefficient of performance and an engine driving the variable displacement compressor can be operated at high fuel efficiency. Also, the refrigerant is temporarily controlled so as to have negative superheat.

Abstract: The object of the present invention is to prevent refrigerant from flowing out into a vehicle compartment due to damage to an evaporator or piping associated therewith. A solenoid valve is arranged at an inlet of an evaporator, and a check valve is arranged at an outlet of the evaporator. When operation of a system is to be stopped, the solenoid valve is closed while a compressor is kept operating for a predetermined time to suck out refrigerant from the evaporator to a downstream side of the check valve, so that during stoppage of the operation, the check valve prevents the refrigerant from flowing back into the evaporator. Thus, even if the evaporator arranged in the vehicle compartment or piping associated therewith is damaged, a situation where a large amount of refrigerant flows out of the evaporator into the vehicle compartment does not occur because no refrigerant remains in the evaporator, making it possible to prevent occupants in the vehicle compartment from being put in a grave situation.