Power plants – Pressure fluid source and motor – Pulsator
Reexamination Certificate
1999-06-03
2001-10-02
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Pulsator
C092S052000
Reexamination Certificate
active
06295813
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to fluid actuated cylinders and more particularly to an actuator for fluid actuated cylinders.
BACKGROUND OF THE INVENTION
Press driven tool modules utilizing fluid actuated cylinders have found acceptance due to their adaptability to conventional presses wherein a vertical force input by a press ram to one fluid power cylinder actuates a second fluid work cylinder to provide a horizontal or otherwise directed force output to actuate a tool to form a portion of a workpiece inclined to the axis of the press ram. This design is flexible in that various tool modules can be used with the same press to provided a number of forming operations actuated by a single press. One such press driven fluid actuated tool module is disclosed in U.S. Pat. No. 5,606,910. In this system a press ram displaces a piston of a hydraulic power cylinder to pressurize the hydraulic fluid and thereby displace a piston of a work cylinder which has a tool mounted thereon to engage the tool with the workpiece. The power cylinder has an upper reservoir containing a reserve supply of hydraulic fluid which when the piston is retracted communicates with a lower portion of the cylinder, which contains the hydraulic fluid to be pressurized by displacement of the piston, after it engages with a high pressure seal to prohibit pressurized fluid from flowing into the upper reservoir. The power cylinder must be disposed in substantially vertically upright position to function properly. When the high pressure seal wears, there is, at the very least, a loss in pressure of the hydraulic fluid when the work cylinder piston is displaced which reduces the efficiency of the system and effects the performance of the work tool in use. Further, wear on the seal can lead to failure of the power cylinder requiring replacement of the entire power cylinder or at least the high pressure seal resulting in increased down time for the system.
SUMMARY OF THE INVENTION
For a hydraulically actuated device a hydraulic power cylinder with an actuator slidably received for reciprocation within the cylinder and a piston slidably received for reciprocation within the actuator and defining in part a gas chamber on one side of the piston and a hydraulic fluid chamber on the other side of the piston so that the maximum pressure in the hydraulic fluid chamber is limited as a function of the pressure of gas in the gas chamber acting on the piston. In this way, the maximum system pressure corresponds to the pressure of the gas within the gas chamber acting on the piston. Desirably, the pressure within the gas chamber can be readily changed to change the maximum hydraulic fluid pressure.
In one form, the hydraulic actuator is used to drive a work cylinder having a work tool to form a workpiece adjacent the work cylinder. Preferably, a press displaces the actuator to decrease the volume of the hydraulic chamber and force hydraulic fluid under pressure from the hydraulic actuator to the work cylinder to drive a piston and rod of the work cylinder to displace the associated work tool to form the workpiece. A biasing member in the work cylinder acting on its rod and piston returns the hydraulic actuator to its unloaded position when the press ram is retracted from the actuator. The biasing member may be one or more gas springs carried by the work cylinder.
Objects, features and advantages of this invention include providing a hydraulic actuator which limits the maximum pressure within the hydraulic actuator and within a device driven by the hydraulic actuator, is readily adaptable to many hydraulic cylinder applications, enables the maximum hydraulic fluid pressure to be readily varied, improves the in-service useful life of the high pressure seals, is reliable durable, of relatively simple design and economical manufacture, and has a long useful life in service.
REFERENCES:
patent: 2786409 (1957-03-01), Claire
patent: 5303906 (1994-04-01), Cotter et al.
patent: 5606910 (1997-03-01), Katz
Diebolt International, Inc.
Lazo Thomas E.
Look Edward K.
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
LandOfFree
Press driven tool actuator module does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Press driven tool actuator module, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Press driven tool actuator module will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2589025