Applied Power Inc.

Dynex/rivett, Inc.

Dale A Knutson

George R Steber

Frank M Fritz

Douglas P Miller

Kishor J Patel

James P Janecke

Thomas J Stobbs

A system for tightening a threaded fastener with a hydraulic wrench has a pumping unit which measures parameters representative of the torque applied to the fastener and the angle of advance of the fastener, remote from the wrench. The pump measures pressure as a parameter representative of torque and measures, pump speed as a parameter which is processed so as to be representative of the angle of advance of the fastener. A ratchet-type hydraulic wrench is used, and the pressure versus angle data produced in tightening a fastener is manipulated to discard irrelevant portions and smooth relevant portions to provide data representative of torque and angle during the tightening process from which to determine a final stopping parameter for terminating tightening. The system also has a calibration fixture for determining the volumetric rate of angle advance for a given wrench. Any tightening methodology dependent upon angle may be used to practice the invention, or the invention may be applied to monitor the tightening process.

Pumping unit with speed transducer

A system for tightening a threaded fastener with a hydraulic wrench has a pumping unit which measures parameters representative of the torque applied to the fastener and the angle of advance of the fastener, remote from the wrench. The pump measures pressure as a parameter representative of torque and measures flow rate, pump speed (for a fixed displacement pump), or time (for a fixed displacement pump driven at constant speed) as a parameter representative of the angle of advance of the fastener. A ratchet-type hydraulic wrench is used, and the pressure versus angle data produced in tightening a fastener is manipulated to discard irrelevant portions and smooth relevant portions to provide data representative of torque and angle during the tightening process from which to determine a final stopping parameter for terminating tightening. The system also has a calibration fixture for determining the volumetric rate of angle advance for a given wrench. Any tightening methodology dependent upon angle may be used to practice the invention, or the invention may be applied to monitor the tightening process.

Method and apparatus for hydraulically tightening threaded fasteners

A piezo-electrically actuated hydraulic valve has a nozzle type seat and a piezo-electric actuator in a plane orthogonal to the axis of the nozzle. The actuator includes a piezo-ceramic layer laminated to an electrode sheet, so that the composite is in sheet form and parallel to the plane of the seat. The electrode sheet has opposite edges which extend beyond the piezo-ceramic layer and are clamped by the housing of the valve so that the center of the actuator is positioned over the seat, and in the preferred embodiment normally closes the seat. When an electric field is applied to the piezo-ceramic layer, the actuator bows or dishes so as to displace relative to the nozzle. The electric field may be applied proportionally, in which case the actuator displaces proportionally to the field applied, the field may be applied as a pulse width modulated signal, in which case the displacement of the actuator also modulates. The actuator has an electrode coating applied over the ceramic layer, which may be divided into motor and generator sub-areas, and an area of the coating is absent where the ceramic layer seats against the nozzle. Rectangular and circular actuators are disclosed.

Piezo composite sheet actuated valve

A piezo-electrically actuated fluid control valve has a nozzle type seat, a magnet opposite from the seat, and a piezoelectric actuator in sheet form between the seat and magnet. The actuator includes a piezo-ceramic layer laminated to an electrode sheet, so that the composite is parallel to the seat and a surface of the magnet. The electrode sheet has opposite edges which extend beyond the piezo-ceramic layer and are clamped by the housing of the valve so that the center of the actuator is positioned between the seat and magnet. When an electric field is applied to the piezo-ceramic layer, the actuator bows or dishes so as to displace from the seat toward the magnet, and the magnetic field of the magnet draws the actuator further away from the seat, to increase the valve opening between the actuator and the seat. The actuator may be operated by a pulse width modulated or a proportional analog electrical signal, which may be applied in combination with the magnetic field to move the actuator, or if the magnetic field is induced by an electromagnet, electrical and magnetic control modes may be used alternatively.

Magnetically assisted piezo-electric valve actuator

A direct-operated, two-way solenoid valve is disclosed. The valve balances the hydraulic flow forces acting on a poppet in order to achieve fast-acting, high-flow operation. The valve has a housing with the poppet mounted in a main bore. The poppet has a sealing end with a longitudinal central bore that is open at the sealing end and terminates in a pressure wall. A radial cross bore in the poppet provides fluid communication between the central bore and an outlet port formed in the housing. The sealing end of the poppet may contact a valve seat to prevent fluid communication between an inlet port formed in the housing and the central bore of the poppet. The sealing end of the poppet is biased into contact with the valve seat to prevent fluid communication between the inlet port and the central bore. An actuator generating a magnetic flux path tends to move the poppet out of contact with the valve seat.

Fluid control valve

A compact, high response regulating valve has a solenoid modulated armature and plunger construction. The solenoid assembly and armature minimize magnetic flux leakage by maintaining the armature in close proximity to the induced magnetic field. In one embodiment, the lightweight armature has a number of holes to increase the speed at which it may be modulated. Mounted to the armature is a regulator plunger which controls fluid communication between the valve's inlet and outlet ports. Normally spring-biased closed, the plunger uses a line seal to maximize flow with minimal longitudinal plunger movement. Plunger response time is enhanced by eliminating elastomeric friction (i.e., eliminating O-rings and replacing them with a number of notches about the plunger periphery). A conical seat and bevelled plunger provide an effective line seal.

High response, compact solenoid two-way valve

A valve has a magnetic drive unit axially spaced from a valve section. An axially movable armature is moved by an electromagnet and an annular permanent magnet having radial magnetization. Reciprocation of the armature opens and closes a poppet valve to regulate fluid flow between two chambers. The magnetic characteristics of the magnetic drive unit are such that the armature remains in either of two axial limit positions when current is not being applied to the electromagnetic coils. In order to compensate for fluid flow forces tending to close the poppet when open, a biasing spring is also used to help overcome these forces. In an embodiment applied to vehicle shock absorbers, an orifice plate and disc springs are used adjacent the poppet structure to permit damping characteristics which vary depending on whether the piston or the shock absorber is compressing or rebounding.

Electromagnetic valve utilizing a permanent magnet

A pressure regulator includes an inlet adapted to be connected to a pressure source and a chamber in which the pressure is to be regulated. An orifice is provided between the inlet and the chamber for metering the flow of hydraulic fluid therebetween. In addition, regulating means is provided adjacent the orifice and is movable in a timed relation in response to a series of pulse signals for changing the effective flow area of said orifice whereby the pressure in the chamber varies with the integral of the voltage pulses.

Pressure regulator

Disclosed is an electrohydraulic proportional valve comprising an electromagnetic force motor, a pilot actuator assembly, and a main spool and body assembly. The pilot actuator assembly comprises a pilot spool slidably received in a pilot sleeve and a feedback spool which has a camming surface against which the pilot sleeve rides. The camming surface comprises a first portion in which the position of the pilot sleeve is a function of the axial position of the camming surface and a second portion immediately adjacent the first portion in which the position of the pilot sleeve is constant regardless of the axial position of the camming surface. The main spool and body assembly comprises a main spool connected to the pilot actuator assembly, first and second load holding check valves slidably disposed in a bore, first means for communicating pilot supply pressure to a reduced diameter area on the main spool when it is the float position, and second means for communicating pilot supply pressure from the reduced diameter area on the main spool to the bore between the first and second load holding check valves when the main spool is in its float position.

Electrohydraulic proportional valve

An electromechanical force motor including an elongate magnetic casing which coaxially enhouses a magnetic armature. An annular electromagnetic coil surrounds the armature and is axially positioned between a pair of permanent magnets having axially directed poles. A magnetic pole is positioned at each end of the armature in a posture juxtaposed to but spaced from the ends of the armature to provide a magnetic flux gap between the armature and poles. A pushrod is connected to one end of the armature and projects outwardly from the casing to produce work upon excitation of the electromagnetic coil.

Electromechanical force motor

A proportional flow control valve comprises a directional control valve having a valve spool, a servo actuator or servo means for operating said directional control valve, and manual override means for operating the valve spool. The servo means comprises a movable ram or piston for moving the valve spool to thereby operate the directional control valve and the ram has a pair of equally sized piston areas connected thereto. The servo actuator also comprises a pilot valve having a null position and is selectively operable to apply fluid alternately to either of said piston areas to effect ram and valve spool movement in one direction or another from a null position. Means including a proportional electromagnetic device such as a proportional solenoid or force motor are provided for selectively operating the pilot valve. Feedback means are connected between the ram and the pilot valve to maintain the ram and the valve spool in a position wherein they are moved. Orifice means are connected between the pilot valve and the piston areas for relieving fluid pressure on one piston area when fluid pressure is being applied to the other piston area. The orifice means also serve to relieve the fluid pressure on both piston areas whenever the signal to the proportional solenoid is zero and the pilot valve is in null position to thereby prevent ram movement. Biasing means are provided on the valve spool for maintaining the ram and the valve spool in null position whenever the proportional solenoid signal is zero. The biasing means exert a force on the valve spool which is less than the force exerted by fluid being applied to a ram area whenever an electric signal is applied to the proportional solenoid. The override means are manually operable to move the valve spool by means of a mechanical linkage to effect manual operation of the directional control valve.

Proportional flow control valve

A hydraulic system and latching mechanism for a cab tiltably mounted to the chassis of a vehicle. The cab is normally disposed over the engine of the vehicle and is pivotally attached to the chassis at its forward end for movement through 90.degree.. The cab is powered by an air-motor-actuated hydraulic pump which energizes lifting cylinders disposed between the chassis and cab. When the system is energized, a hydraulically actuated latch is released prior to commencement of the tilting movement of the cab. A direction-control valve is employed which, when in the neutral or closed position, utilizes the pressures generated in the hydraulic system by the weight of the tilted cab in certain positions to assist the valve in sealing the reservoir port in the valve against leakage thereby preventing the cab from creeping.

Tilt cab power stream and valve control therefor

A proportional force amplifier having a cylinder separated by a piston assembly into a pressure chamber, a control chamber and a reservoir chamber, a spool valve mounted for axial movement within a bore in said piston assembly to selectively connect the control chamber to either the pressure chamber or the reservoir chamber, the piston assembly moving in response to the change in pressure between the pressure chamber and the control chamber a distance equal to the distance of movement of the spool valve, the spool valve being connected for actuation by a resilient compensating rod and being pressure balanced.

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Nashotah, WI, United States of America

Dale A Knutson