Hydraulic circuit system for one-touch jack and its structure

  • US 5,755,099 A
  • Filed: 11/01/1996
  • Issued: 05/26/1998
  • Est. Priority Date: 11/01/1996
  • Status: Expired due to Term
First Claim
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1. A one-touch jack comprising:

  • a) a hydraulic cylinder having a movable piston rod extending therefrom with a portion of the piston rod located in an inner chamber of the hydraulic cylinder, the piston rod having an inner oil chamber therein, the hydraulic cylinder having an outer reservoir;

    b) a pump having a pump oil chamber and a plunger movable into and out of the pump oil chamber, a volume of the pump oil chamber being at least as large as a volume of the inner oil chamber of the piston rod;

    c) an oil inlet circuit comprising;

    a first oil channel extending between the pump chamber and outer reservoir, a first check valve located in the first oil channel so as to allow hydraulic flow from the outer reservoir into the pump oil chamber and prevent flow in the reverse direction;

    a second oil channel extending between the pump oil chamber and the inner oil chamber of the piston rod, a second check valve located in the second oil channel to allow hydraulic flow from the pump oil chamber into the inner oil chamber of the piston rod when the plunger is moved into the pump oil chamber, and to prevent flow in the reverse direction;

    a third oil channel extending between the outer reservoir and the inner chamber, a third check valve located in the third oil channel to allow hydraulic flow from the outer reservoir into the inner chamber and to prevent flow in the opposite direction; and

    a fourth oil channel extending between the inner chamber and the second oil channel ahead of the second check valve, a sequence valve located in the fourth oil channel closing the fourth oil channel until a predetermined pressure is reached in the second oil channel, the sequence valve opening at the predetermined pressure to enable hydraulic flow from the second oil channel into the inner chamber, the sequence valve comprising;

    i) a hollow post threadingly connected to the hydraulic cylinder in the fourth oil channel;

    ii) a first conical valve element; and

    iii) a spring bearing against the hollow post and the first conical valve element biasing the first conical valve element toward a closed position, whereby a predetermined opening pressure may be set by rotating the hollow post to move the hollow post toward or away from the first conical valve element to vary the spring biasing force; and

    ,d) an oil return circuit comprising;

    a fifth oil channel extending between the outer reservoir and the fourth oil channel at a location between the hollow post and conical valve element, the fifth oil channel also communicating with the inner oil chamber of the piston rod, a relief valve located in the fifth oil channel to selectively open or close the fifth oil channel.

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