Patent Application
20130333556
1. Field of the Invention
The present invention relates to a pump piston structure of a hydraulic cylinder, and more particularly to the structure having a penetrating hole formed between a pump piston and a piston rod and blocked by a pressure valve, and the pump piston includes an aslant circular groove formed on a circumferential surface of the pump piston and interconnected to a through hole on a distal surface, and a movable O-ring is installed in the aslant circular groove for enhancing the suction efficiency of a hydraulic oil and reducing the resistance of operating a jack.
2. Description of Related Art
In general, the lifting operation of a conventional hydraulic cylinder relies on a pump piston to suck hydraulic oil from an oil suction hole and then push the hydraulic oil into an oil outlet to drive a hydraulic rod, such that a stroke of the hydraulic rod can drive and lift a heavy object.
However, a conventional piston of a jack simply has a piston structure, so that the jack can only output a fixed quantity of hydraulic oil to push the hydraulic rod regardless of whether or not it is at the time when the hydraulic cylinder starts lifting a heavy object (since the resistance differs at the time before/after the hydraulic rod has pushed the hydraulic oil to a position in contact with the heavy object). To achieve a quick lifting effect, the oil suction quantity of the jack is increased. Although the effect of lifting the hydraulic rod quickly can be achieved by increasing the oil suction quantity, yet the resistance of operating the jack is also increased (wherein the impelled quantity of the hydraulic oil is increased for each up-and-down stroke for sucking hydraulic oil, and thus the resistance of the jack is increased). As a result, the hydraulic rod has a very quick lifting stroke before the heavy object is lifted, but the resistance becomes relatively larger as long as the hydraulic rod is loaded with the heavy object, and thus such arrangement has the drawback of requiring much laborious efforts for users to operate the jack. On the other hand, the oil suction quantity of the jack can be reduced to provide an easy operation of the jack loaded with a heavy object, but it takes a longer time before the hydraulic rod can be lifted to a position in contact with the heavy object, and thus such arrangement has the drawback of a time-consuming operation.
Therefore, it is a primary objective of the present invention to provide a pump piston structure of a hydraulic cylinder, particularly the structure with a pump piston having an aslant circular groove formed on a circumferential surface of the pump piston and interconnected to a through hole on a distal surface, a movable O-ring installed at the aslant circular groove, a penetrating hole formed between a distal surface of the pump piston and a piston rod and blocked by a pressure valve, and an oil suction hole formed separately on the pump piston and the piston rod for sucking hydraulic oil to push the hydraulic cylinder in reciprocal movements of the pump piston, so that the invention can achieve the following effects:
Since the jack of the present invention has an oil suction hole interconnected to the pump piston and the piston rod separately, and the pump piston has an aslant circular groove formed on a circumferential surface of the pump piston and interconnected to a through hole on a distal surface, and a movable O-ring is installed at the aslant circular groove, therefore when the hydraulic rod is lifted to a position not in contact with the heavy object yet, the hydraulic oil at the pump piston can be outputted when the jack is pressed down, and the hydraulic oil at the piston rod is sucked. When the jack is pushed upward, the hydraulic oil at the pump piston can be sucked through the oil suction hole, and the hydraulic oil at the piston rod can flow through the aslant circular groove and the through hole to the pump piston, so that the jack can be operated more efficiently in the process of sucking hydraulic oil. Further, when the hydraulic rod starts loading a heavy object to produce a greater resistance, the jack is pressed down to drive the pump piston to push the hydraulic oil and thus also produces a larger pressure. As a result, the pressure of the hydraulic oil at the pump piston can push open the pressure valve and let a part of the hydraulic oil flow towards the piston rod and the other part of the hydraulic oil be outputted to the oil outlet, so as to push the hydraulic rod (wherein the cross-sectional area of the hydraulic oil at the pump piston is greater than the cross-sectional area of the piston rod. In the operations of the same jack, the output quantity of the hydraulic rod hydraulic oil drops automatically to assure an easy operation of lifting the heavy load when the heavy object is loaded, so as to achieve the effect of lifting the hydraulic rod quickly before the heavy object is lifted and the advantage of reducing the resistance of operating the jack after the heavy object is lifted.
The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.
With reference to
With the aforementioned components, the piston rod 2 of the pump 10 drives the pump piston 1 to move up and down reciprocally in the oil chamber 20. Since the pump piston 1 is abutted against the inner wall of the oil chamber 20 through the movable O-ring 13 (as shown in
When the pump piston 1 moves upward, the hydraulic oil at the piston rod 2 and the oil suction hole 4 is filled into the space below the pump piston 1 to allow the users to operate the pump 10 reciprocally.
The pressure valve 15 is formed by using a spring 151 to prop a bead 152 to seal a penetrating hole 14.
In summation of the description above, the pump piston 1 of the present invention can lift the hydraulic rod 101 quickly before lifting a heavy object. When the hydraulic rod 101 is loaded with the heavy object, the output quantity of hydraulic oil is reduced automatically to assure that users can lift the heavy object easily.
While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
