Power plants – Pressure fluid source and motor – Ram driven by fluid pumped from reservoir
Reexamination Certificate
1999-10-08
2001-03-13
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Ram driven by fluid pumped from reservoir
C060S481000, C060S482000
Reexamination Certificate
active
06199379
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an oil circuit of a jack for rising an object to a preset position rapidly, which improve the device disclosed in U.S. Pat. No. 5,755,099 so that the piston rod can attain a still state rapidly. The inner oil chamber of the piston rod is communicated to inner oil reservoir so that the inner and outer oil pressure of the oil tube are equal so that breakage is prevented.
BACKGROUND OF THE INVENTION
In using a conventional hydraulic jack, despite of dummy load or loading condition, the handle must move repeated many times so as to drive the oil cylinder to work. However, since in dummy load or light load, it still needs to be driven repeated, much work is wasted. Therefore, the invention in U.S. Pat. No. 5,755,099, “Hydraulic Circuit System for One Touch Jack and Its Structure”, discloses a jack structure, in which the jack hydraulic loop circuit includes an oil inlet circuit, an oil return circuit and an overload protecting circuit.
In the oil inlet circuit, the outer oil reservoir is communicated to the pumping oil chamber through a check valve. The pumping oil chamber is communicated to a oil guiding tube through another check valve, The oil guiding tube is embedded into the inner oil chamber in the piston rod for forming as a loop. The pumping oil chamber is communicated to the inner oil reservoir of the piston rod through a sequential valve B. The outer oil reservoir is communicated to the inner oil reservoir of the hydraulic cylinder through a check valve. When a manual pump is in dummy load or light load, the oil circuit provides hydraulic oil to the inner oil chamber of the piston rod from the pump and through the oil guiding tube.
In the oil return circuit, the inner oil reservoir is communicated to the inner oil chamber of the piston rod through a check valve, then it further passes through a release valve to be communicated to the outer oil reservoir. When oil is unloaded and then it desires to the original position, the release valve can be adjusted to a release position so that the oil return circuit is conducted.
In the overload circuit, an outer oil reservoir passes through a safety valve to be communicated to the oil chamber of a manual pump. When the pressure of the hydraulic cylinder is over a rated pressure, the safety valve will be conducted so that the overload protecting circuit will open automatically. In the aforesaid hydraulic loop system, the maximum effective oil storing amount of the pumping oil chamber of the manual pump is large than or equal to the maximum effective oil storing amount of the inner oil chamber in the piston rod so that the hydraulic jack may rapidly rise to a loading position in dummy or light load condition.
However, in above invention, for the check valves in the oil circuit and the oil channels, since when the piston rod move to a position in one touch, the oil guiding tube and the inner oil reservoir are in still condition. Thus, the inner and outer pressures of the oil guiding tube in the piston rod are unequal, the oil guiding tube must suffer from a large still load pressure. Therefore, the pressure-resistance of the oil guiding tube must be further improved, but this will increase the cost. If the pressure-resistance of the oil guiding tube is insufficient, it is possible to break out. Therefore, many considerations in safety are concerned for the prior art design.
SUMMARY OF THE INVENTION
Accordingly, the primary object of the present invention is to provide an oil circuit of a jack for rising an object to a preset position rapidly, wherein the oil inlet circuit of a hydraulic loop system is improved. An oil channel is installed between the inner oil chamber of the piston rod and the sequential valve. A check valve is installed between the oil channel and the sequential valve. An oil channel is installed between the sequential valve and the check valve for being connected to the inner oil chamber of the piston rod. By changing the positions of the check valve and the oil channel. When in the working conditions of dump load or light load, the sequential valve is closed, thus, the hydraulic oil may enter into the inner oil chamber of the piston rod from the pumping oil chamber through the check valve so that the piston rod will rise rapidly to a still condition. In the still condition, since the check valve closes the oil channel, the sequential valve will open automatically so that the inner oil chamber of the piston rod is communicated to the inner oil reservoir. Thus the inner and outer oil pressures of the oil guiding tube in the piston rod are equal. Thus, no strong still load hydraulic pressure exists in the oil guiding tube within the inner oil chamber of the piston rod. BY this changing, the still load hydraulic pressure of the inner oil reservoir and the inner oil chamber of the piston rod can be adjusted equilibrium by the sequential valve. Therefore, the problem of breakage of the oil guiding tube of the piston rod and the high cost due to confinement in material are solved. Moreover, the sequential valve can be located outsides so that the sequential valve is adjustable outsides to a preset actuating pressure.
Another object of the present invention is to provide an oil circuit of a jack for rising an object to a preset position rapidly, wherein the sequential valve is located outsides with a 90 degrees of position shift, and a connecting oil channel is installed between a ball vale and the inner oil reservoir so that the adjusting nut of the sequential valve is locked to the outer wall of the rear seat of a jack. The sequential valve B can be located outsides so that the sequential valve is adjustable outsides to a preset actuating pressure.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.
REFERENCES:
patent: 5755099 (1998-05-01), Hung
Bacon & Thomas PLLC
Leslie Michael
Look Edward K.
MVP ( H.K.) Industries Limited
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