Showing papers on "Hydraulic machinery published in 1987"

Intrapulmonary pressure monitoring system

Abstract: A pressure sensing device hydraulically coupled with a transducer comprising a closed hydraulic system incorporated within an endotracheal tube to monitor intrapulmonary pressure. The tube employs an hydraulic system for conveying pressure data from a distal sensor, on the tube, to a transducer. The sensor and transducer are connected by a liquid-filled lumen. Use of an hydraulic conduit avoids the errors of gas-filled systems because liquids, such as the water used in this system, are incompressible.

Hydraulic system for the mold clamping unit of a plastics injection molding machine

Abstract: A hydraulic actuator assembly for use in a mold clamping unit of an injection molding machine. The actuator assembly serves as a rapid-travel drive for mold opening and closing movements and as a source of elevated mold clamping pressure. Among the hydraulic elements contributing to the operation of the mold clamping unit are a power piston for effecting elevated mold clamping pressures and a drive piston for effecting rapid die closing movements. With the hydraulic actuator system of the present invention, it is possible to control the operation of the mold clamping unit based on two-sided hydraulic influencing of the power piston and the drive piston.

Control system for controlling input power to variable displacement hydraulic pumps of a hydraulic system

Abstract: A control system for controlling input power to hydraulic pumps of a hydraulic system including a prime mover and a plurality of variable displacement hydraulic pumps driven by said prime mover. The control system comprises: a first computing unit for computing, for each of the hydraulic pumps, an input torque control value concerning a distribution of input torques of said hydraulic pumps from a representative pressure obtained on the basis of a discharge pressure of at least one other hydraulic pumps; a second computing unit for determining an input torque for each of the hydraulic pumps on the basis of a corresponding one of the input torque control values determined by the first computing unit; and a third computing unit for determining an object discharge rate of each of the hydraulic pumps from the input torque obtained by the second computing unit and an own discharge pressure of each of the hydraulic pumps.

Control apparatus for variable-speed hydraulic power generating system

Abstract: Disclosed is a control apparatus for a variable-speed hydraulic power generating system comprising a variable-speed a.c. electric generator connected to an a.c. electric power system and a hydraulic machine system including a water turbine for driving the generator and a guide vane for controlling an amount of water supplied to the water turbine. The control apparatus comprises a frequency converter connected between the electric power system and the generator for controlling electric power supplied from the generator to the electric power system, control means operating in response to at least an externally applied power generation command signal for controlling, on one hand, the frequency converter thereby controlling the electric power supplied from the generator to the electric power system and generating, on the other hand, a guide-vane opening command signal for controlling the guide vane thereby controlling the amount of water supplied to the water turbine, and means for reducing resonance which may occur in the hydraulic machine system when the rotation speed of the water turbine changes in response to a change of the externally applied power generation output command signal.

Pressure checked electrical pressure switch

Abstract: An electrical pressure switch (12) is used on a hydraulic system to indicate the presence of a minimum operating pressure. The hydraulic fluid acts on a piston (34) to move the piston (34) against a force exerted by a calibration spring (46). Movement of the piston (34) ultimately closes the contacts (72, 76, 78) of a switch (58), thereby delivering an electrical signal indicative of minimum operating pressure. A check valve (86, 90) moves in concert with the piston (34) and isolates the internal structure of the pressure switch (12) from escalating hydraulic pressure.

Electro-magnetic-hydraulic valve drive for internal combustion engines

Abstract: Valve drive for a combustion engine with an hydraulic transmission system between a control member and a valve includes a device for stepping up the hydraulic transmission.

Actively controlled automotive suspension system with mutually independent hydraulic systems having mutually different damping characteristics for improving response characteristics in active suspension control

Abstract: An actively controlled suspension system has two hydraulic systems for generating damping force against the vibration to be transmitted between a vehicle body and a suspension member (13). One of the hydraulic systems is designed for absorbing relatively high frequency vibration generally input from the suspension member for preventing vibration from the suspension member t=from being transmitted to the vehicle body. The other hydraulic system is active on relatively low frequency of vibration generally input from the vehicle body upon change of attitude of the vehicle body. The other hydraulic system generates a fluid pressure suppressing the attitude change. A pressure control valve (18) and a fluid pressure source (20) may be incorporated in the second hydraulic system so that they may not be active when aforementioned one of the hydraulic system is active.

Hydraulic power wrench

Abstract: The power wrench comprises a housing (10) with a rearward housing member (12) which forms a protection against bursting for the hydraulic cylinder (27) arranged within the housing member (12) Through a joint (38, 40) and self-aligning, the piston (35) acts upon the lever (18) which is supported coaxially to the ring (14) The lever (18) comprises a ratchet element (17) being supported at the lever (18) by a semisperical pressure member (20) The power wrench can be submitted to extremely high hydraulic pressures without a danger to the environment

Utility vehicle designed for frequent starting and stopping

Abstract: The invention is concerned with improvements in utility vehicles having hydraulically driven items of equipment and designed for frequently stopping and starting, such as a garbage collection vehicle, a forklift truck, an excavator or the like. In order to facilitate operation of the equipment the vehicle has its engine connected with a hydromechanical four-shaft power branching transmission as previously proposed for use in city omnibuses operating city services. The branching transmission is adapted for operation in at least two working ranges and has at least two hydroconverters. The one hydroconverter is connected with a power output shaft at least in the starting up state of the vehicle. A second hydroconverter is connected with a shaft different to the transmission input shaft and the transmission output shaft. The pumps of the hydraulic power circuitry for operation of the equipment of the vehicle are able to be connected via clutch with the shaft of a hydroconverter, more especially of the second hydroconverter. This avoids the necessity of having a special auxiliary output transmission driven by the engine.

Wave powered propulsion system for watercraft

Abstract: A watercraft is provided with a propulsion system having a hydraulic power plant driving a propeller through a transmission. The power to operate hydraulic pumps in the power plant is derived from wave motion by buoyant members connected to the power plant by outrigger arms. Undulation of the waves is converted to fluid pressure by the vertical movement of the buoyant members reciprocating pistons in the hydraulic pumps. Pressurized fluid is applied to a fluid motor driving the transmission. A steering assembly is operatively associated with one of the buoyant members.

A new high speed cavitation tunnel for cavitation studies in hydraulic machinery. ASME, Boston, December1987

Abstract: Note: Using Smart Source Parsing Dec. pp 3 Reference LMH-CONF-1987-005 Record created on 2005-11-04, modified on 2017-05-10

Cylinder for hydraulic systems

Abstract: Cylinder for hydraulic systems, in particular for motor vehicles, consisting of a housing with an axial bore in which a piston is guided in an axially displaceable manner and is acted upon on the one end face by hydraulic fluid, the cylinder being provided with connections for at least one pressure-medium line, a connection to a fluid chamber and for fastening. To design a safe and simple connection, which can be assembled without auxiliary tools, for the pressure-medium line on the cylinder, the connection is designed as a push-in connection.

System for supporting a working unit

Abstract: A hydraulic system (30) suitable for raising, lowering, floating and locking a cutting deck (16) Hydraulic circuit (30) preferably includes a back pressure system (40) for automatically, or manually, applying a preferred back pressure to hydraulic cylinders (24) to "float" decks (16) Connected to back pressure system (40) is an actuation system (42) which can automatically or manually act on back pressure system (40) to change the back pressure depending on conditions For example, it may be desirable to increase the back pressure when mower (10) encounters a hill to transfer more weight from the cutting unit (16) to the traction vehicle (12) of mower (10)

High efficiency pump method and apparatus with hydraulic actuation

Abstract: A method and apparatus for pumping water, oil, or other production fluid up a production tube from a well or the like to achieve greater efficiency as compared to conventional pumpjacks. A hydraulic actuator unit with its own hydraulic fluid incorporates pressure sensing valves to move a hydraulic piston through a power stroke and a resetting stroke. A power transmission tube having its own power fluid transfers pressure from the hydraulic actuator to a downhole piston assembly to pump the production fluid directly up the production tube during a power stroke. The static head of the production fluid in the production tube resets the downhole piston assembly during the resetting stroke. The pressure sensing valves enable the hydraulic piston to extend its power stroke a sufficient distance to pressurize the power transmission fluid and move the downhole piston assembly through its entire production stroke independent of the compressibility of the power transmission fluid. Another embodiment provides for two power tubes respectively coupled through pulser units to opposite ends of the hydraulic piston to alternately pressurize the power tubes thus making each stroke of the hydraulic piston a combined power/resetting stroke. Each of the embodiments is applicable for single and multiple well installation.

Arrangement for operating a diesel hydraulic drive

Abstract: An arrangement for operating a diesel-hydraulic drive on a construction machine in limit-load control with a microprocessor controller in which the installed hydraulic power is greater than the rated output of the diesel engine. Upon thermal and/or diesel-engine overload the hydraulic power which can be taken off is reducible; in the case of non-output loading, after a selectably predetermined time the diesel engine can be switched to idling speed of rotation and hydraulic displacement pumps can be operated with minimum delivery oil quantity; and the adjustable hydraulic displacement pumps can be adjusted in accordance with selectably predeterminable output curves.

Hydraulic fluid replenishment device

Abstract: A device for automatically replenishing and exchanging hydraulic fluid in the hydraulic system (such as that of a fastener placing tool (31)) comprises a lower reservoir (29) for holding new hydraulic fluid (39) and an upper reservoir (28) for receiving old hydraulic fluid. The device connects with the system to be replenished by means of a single hydraulic fluid connection (17) at the bottom of the lower reservoir (29). An entry port (25) to the second reservoir is positioned opposite the connection (17) at the bottom end of a tube (23) leading to the top of the second reservoir. In use, the device is connected to the hydraulic system through the connection (17) and the system is pressurised. Old hydraulic fluid is forced up through the connection (17) at high speed and passes through the new hydraulic fluid (39) in the lower reservoir (29), through the port (25), up the tube (23) and down into the upper reservoir (28) where it is retained. When the system is depressurised, new hydraulic fluid (39) is drawn down through the same connection (17) into the hydraulic system.

Remote control system for a soil compactor

Abstract: A hydraulic operated control system for remotely operating a walk-behind soil compactor. A remotely operated three-position valve is connected to the pressure line of the hydraulic system of the soil compactor and serves to control the flow of hydraulic fluid to opposite ends of a hydraulic cylinder unit that is operably connected to a hydraulic pump which operates the speed and direction control for the compactor. The cylinder unit includes a piston that is slidable within the cylinder and the piston is biased to a neutral position by springs. Through remote operation of the valve, hydraulic fluid will be directed to either end of the cylinder to provide direction and speed control for the compactor. A deadman switch is located on the remote control panel and manual release of the deadman switch will open the hydraulic circuit between the opposite ends of the cylinder to prevent fluid from being directed to the cylinder and will enable the springs to return the cylinder to a neutral no speed position. The return line from the cylinder is connected to a second valve which conrols the supply of hydraulic fluid to the steering system for the compactor.

Operator control system

Abstract: An operating control system for a lift truck controlled from a single multi-function operator hand control which is located and designed for improved operator comfort, convenience, simplicity and to reduce operator fatigue. The sole hand control for directional and speed control and the operation of all hydraulic functions of the truck related to the handling of loads is recessed in a compartment adjacent one side of the truck and supported from a control shaft which extends forwardly, leftwardly and downwardly and along which the control handle may be pushed or pulled linearly to control all such hydraulic truck functions. The grip handle is rotatable to control direction and speed of the truck. Switch controls are located conveniently adjacent the one end of the rotatable grip handle for selecting a variety of hydraulic functions by the same movements forwardly and rearwardly of the operator control handle along the control shaft. Electrical and hydraulic systems control the various hydraulic functions and are operatively connected to the control handle for operator selection of direction and speed of the truck as well as simultaneous operation of any selected hydraulic function one at a time only.

Hydraulic valve-operating system for internal combustion engines

Abstract: A fluidic valve-operating system has a reciprocally-movable plunger for moving a valve of an internal combustion engine between closed and opened conditions. A main circuit has feed and return paths for flow of hydraulic fluid from a reservoir to the plunger and a pump interposed in the feed path and driven by the engine. A breather circuit has feed and return paths for flow of hydraulic fluid from an accumulator to the plunger. A control valve interposed in the feed and return paths of the respective main and breather circuits is actuatable by a piezoelectric valve for switching each of the main and breather circuits between pressure supply and return flow modes with respect to the plunger. The main circuit when switched to its pressure supply mode applies a drive pressure to the plunger which varies proportionally with the speed of the engine to accelerate the plunger along a drive stroke to move the valve form its closed toward its opened condition. The breather circuit allows pressure relief when the plunger has moved a portion of its total stroke. A chamber containing a gas is connected in flow communication with the pump via a piston to provide a variable pressure spring for applying a return pressure to the plunger which varies proportionally with engine speed, opposes but is less than the drive pressure and causes deceleration and return of the plunger to its initial position when main and breather circuits are in return flow modes.

Weight scale for a hydraulic loader and related method

Abstract: A weight scale for a loader operated by a hydraulic system incorporated in equipment and a related method are provided. The scale includes a pressure gauge installed in a hydraulic line of the hydraulic system. The gauge may either be located at a loader boom or the tractor instrument panel. The gauge includes an adjustable pointer to correspond the gauge to the tare weight of the particular loaded it is applied to; a calibration factor which allows the operator to convert from the pressure reading on the gauge to a weight value in pounds or kilograms; and a safety line for warning the operator when the safe load limit of the loader is being surpassed. The method includes the steps of: lifting an object on the loader; sensing the pressure exerted in the system by the gauge when the object is lifted by the loader; displaying the pressure; and converting the pressure displayed to a weight value based on the predetermined calibration factor.

Trailerable earth digging apparatus

Abstract: A small, self-contained portable back-hoe has a wheeled frame with a towing tongue for over-the-road trailering. Pivoted outriggers are connected to the back and a third support is secured to the front of the frame. Cylinder units are coupled to position the supports for digging and in raised position for trailering. The bucket and articulated boom assembly is affixed to the frame with a vertical pivot and includes cylinder units for digging operation thereof. An operator station and a hydraulic power supply source or system is secured to the front of the frame. A special hydraulic supply is integrated into the front framework. The back-hoe boom assembly and operating assembly are balanced about the single axle for convenient positioning. The bucket assembly and three-point support are arranged to minimize the tipping of the frame as a result of the digging forces. A gasoline driven high efficiency industrial-type pump is connected to the cylinder units with a filter and the suction side. A reservoir is built into the front frame structure and includes a watertower element to eliminate air from the hydraulic liquid. The reservoir reliably removes the air from the liquid to avoid pump malfunction.

Vehicular hydraulic brake system with anti-locking

Abstract: A vehicular hydraulic brake system with anti-locking, wherein there is provided a master cylinder (27) with a power booster (9) connected upstream thereof for the purpose of supplying the brake-actuating members (32, 33, 36 37) with pressure. Valves (34, 35, 38, 39) are provided for the pressure control of the brake-actuating members (32, 33, 36, 37) and wherein a pressure piston (23) of the hydraulic power booster (9) can be acted upon by the pressure of an auxiliary pressure source (1) in the brake's release direction. To structurally simplify the brake system, the present invention provides that a housing chamber (24) which can be acted upon by the pressure of an unpressurized supply reservoir (5) or of the auxiliary pressure source (1), alternatively, is confined by an end face of the pressure piston (23) remote from the pedal.

Power-assisted steering system

Abstract: A power-assisted steering system includes a changeover valve unit comprising an input shaft to be rotated by the driver's steering effort applied thereto, an output shaft operatively connected to a hydraulic power cylinder associated with the steering system, a valve assembly for controlling the supply of fluid under pressure from a hydraulic pump to the power cylinder in response to relative rotation between the input and output shafts; and a hydraulic reaction mechanism for applying a reaction force to the input shaft in accordance with a hydraulic reaction pressure applied thereto. The reaction mechanism includes a reaction fluid chamber to be constantly applied with a predetermined small quantity of fluid under pressure and to be applied with a hydraulic pressure caused by relative rotation between the input and output shafts through a throttle. The system is arranged to increase the hydraulic pressure in the reaction fluid chamber in accordance with an increase of travel speed of the vehicle.

Hydraulic operating unit of friction engaging apparatus for transmissions

Abstract: A hydraulic operating unit for the friction engaging apparatus of a transmission provides a hydraulic operating unit which permits the introduction of a low-pressure working fluid to permit the forceable disengagement of the hydraulic operation unit to work against the fluid which would normally urge the unit into engagement. The effective pressure-receiving area on the releasing side of a hydraulic power servo mechanism is made sufficiently large with respect to the effective pressure-receiving area on the engaging side of the servo mechanism while the piston diameter is kept small in order to save space in the construction of the servo mechanism while at the same time permitting the device to effectively disengage the friction mechanism.

Hydraulic dock leveler

Abstract: A hydraulic dock leveler having a pivotable main deck, a lip member pivotably connected to the main deck, and a hydraulic system for pivoting the main deck relative to an adjacent loading dock platform and for power extending and power retracting the lip member between a bridging and stored position. The hydraulic system includes valve means to hydraulically hold the lip member in a fully extended bridging position while the main deck is descending relative to the adjacent loading dock platform. When the main deck reaches its lowest level relative to the loading dock platform, the valve means moves to an open condition and the hydraulic system will simultaneously extend the main cylinder to raise the main deck and retract the lip cylinder to pivot the lip member to a stored position.

Helium charged hydraulic accumulators

Abstract: A helium charged accumulator is disclosed for use in hydraulic fluid pressure systems. The size of the accumulator is optimized for particular operating conditions of specific applications of the hydraulic systems by means of a formula. The formula has, as its terms, the volume of the hydraulic fluid required to power a given device, the compressibility factor of the particular gas used and the temperature and pressure of the gas at the beginning of, during, and at the end of the operation cycle of the accumulator.

Dual reservoir tank for propellant hydraulic fluid for internal combustion engine hydraulically driven cooling fan and for power steering actuating fluid

Abstract: In an automotive vehicle wherein the cooling fan for the internal combustion engine is driven hydraulically by a flow of a first propellant hydraulic fluid, while the power steering device for the steering system is driven hydraulically by a flow of a second propellant hydraulic fluid, reservoirs for storing the first and second propellant hydraulic fluids are provided as first and second tank portions, respectively, of a common reservoir tank, so that the first propellant hydraulic fluid which is more apt to be heated up by friction loss is cooled down by the second propellant hydraulic fluid which remains at ambient temperature as effectively cooled through the power steering fluid circulation system.

Stability and Regulation of a Variable-Displacement Vane-Pump

Abstract: Pressure fluctuations may develop in the hydraulic system of automatic transmissions, even under steady-state conditions. To analyze this phenomenon, a dynamic model was developed for a system which consists of a variable-displacement vane-pump, a regulator, and a resistive load. The model was linearized and reduced to generate a stability criterion for the pressure-regulation circuit. This criterion determines a critical frequency that the natural frequency of the pressure-regulation valve must exceed to assure stability. This critical frequency depends primarily on the daming of the spool of the pressure-regulation valve and on its position; the latter is a function of the regulation-chamber leakage characteristics. The analysis shows that line pressure, flow and leakage, along with production tolerances and different operating conditions, have a significant effect on the stability of the hydraulic system. Test data supports the analysis.