Check valve structure for use in pump of hydraulic cylinder

1. Field of the Invention

The present invention relates to a check valve and, more particularly, to a check valve for use in a pump of a hydraulic cylinder that may prevent the hydraulic oil from leakage during the accelerated operation of the jack.

2. Description of the Prior Arts

The cylinder is an indispensable component provided in jacks due to its high bearing capacity, thus lifting objects easily. However, the conventional cylinder had some disadvantages, such as poor operating stability, slow raising speed and the like. To overcome such defects, an improved cylinder provided with an air operated pump therein had been developed and applied in the related field.

Such an improved air-operated pump utilizes an inputted air pressure to actuate a piston (including a spring element disposed therein and designed in an air venting and a position returning manner). A stem member of the piston is in communication with an oil route of the cylinder so as to cause a pump effect. Thus, the cylinder may generate larger fluid pressure during the operation of the air operated pump for enhancing the operating speed. Thereby, the lifting speed of the jack may be improved. However, such a lifting speed still can be accelerated.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.

The primary object of the present invention is to provide a check valve for use in a pump of a hydraulic cylinder that may prevent the hydraulic oil from leakage during the accelerated operation of the jack.

Another object of the present invention is to provide a check valve for use in a pump of a hydraulic cylinder and including the sealing sleeve replaced by the ring element, thus saving the production cost.

In accordance with one aspect of the present invention, there is provided a check valve for use in a pump of a hydraulic cylinder comprising a check valve including a tubular member disposed therein and having a sheath member received therein. The pump includes a chamber provided in an output pipe thereof for receiving the check valve.

The tubular member is constructed in the form of a hollow cylinder and includes a sealing sleeve fitted therearound. The tubular member includes an oil seal mounted on the front end thereof for engagement with a hollow screw element in the chamber.

The sheath member includes a hollow cap member, a first spring element, a ball, a hollow disc element and a second spring element.

The hollow cap member, the first spring element, the ball and the disc element are placed into the tubular member in turn. By using the disc element and the second spring element, the tubular member may be fixed in the chamber. Thereafter, by way of the screw element, the tubular member is enclosed in the chamber. The front end of the tubular member is matingly engaged with the screw element by using the resilience of the second spring element through the disc element. The sealing sleeve corresponds to an air opening of the chamber, and the ball abuts against the disc element by the first spring element for achieving a checking purpose. The pump may generate air pressure to push the ball away and input the pressure into a cylinder. After the air pressure in the cylinder of a jack is released, the tubular member is pushed to press against the second spring element, so that the tubular member disengages from the air opening. Then, the air pressure vents from the air opening for a quick pressure releasing purpose. Thereafter, the second spring element biases the tubular member to return its initial position such that the air opening may be sealed once more, thus preventing the hydraulic oil from leakage during the accelerated operation of the jack.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustration only, the preferred embodiment in accordance with the present invention.

FIG. 1 is a perspective diagram of a jack according to the present invention;

FIG. 2 is a cross sectional diagram of a pump according to the present inventions;

FIG. 3 is a perspective diagram illustrating the exploded components of a check valve for use in a pump of a hydraulic cylinder according to the present invention;

FIG. 4 is a perspective diagram illustrating the assembly of the check valve for use in a pump of a hydraulic cylinder according to the present invention;

FIG. 5 is a cross sectional diagram illustrating the check valve for use in a pump of a hydraulic cylinder of the present invention being associated with a pump;

FIG. 6 is a cross sectional diagram illustrating the check valve for use in a pump of a hydraulic cylinder of the present invention outputting air pressure;

FIG. 7 is a cross sectional diagram illustrating the check valve for use in a pump of a hydraulic cylinder of the present invention venting the air pressure;

FIG. 8 is a cross sectional diagram illustrating the operation of the pump according to the present invention; and

FIG. 9 is a cross sectional diagram illustrating a tubular member of the present invention being provided with one or more ring elements.

Referring to FIGS. 1 and 2 , a check valve 1 for use in a pump of a hydraulic cylinder in accordance with the present invention includes a tubular member 11 disposed therein and having a sheath member 12 received therein. The pump 2 including a chamber 21 , in communication with an output pipe 20 A, slideably receives the tubular member 11 of the check valve 1 for movement in a movement direction. The chamber 21 has larger cross sections perpendicular to the movement direction than the output pipe 20 A.

The tubular member 11 is constructed in the form of a hollow cylinder and includes a front end 11 A and a back end 11 B. A first passage 26 extends from the back end 11 B towards but spaced from the front end 11 A. A second passage 28 extends from the front end 11 A and in fluid communication with the first passage 26 . The second passage 28 has cross sections smaller than the first passage 26 to define a shoulder 30 . The tubular member 11 further includes a sealing sleeve 111 fitted therearound. The tubular member 11 includes an oil seal 112 mounted on the front end 11 A thereof for the engagement with a hollow screw element 22 in the chamber 21 (as shown in FIGS. 3 and 4 ).

The sheath member includes a hollow cap member 121 , a first spring element 122 , a ball 123 , a hollow disc element 124 and a second spring element 125 .

In assembly, the hollow cap member 121 , the first spring element 122 , the ball 123 and the disc element 124 are placed into the tubular member 11 in turn. The first spring element 122 is sandwiched against the cap member 121 and the shoulder 30 , and the ball 123 is sandwiched in the first passage 26 between the first spring element 122 and the disc element 124 . The second spring element 125 sandwiched between the chamber 21 and the disc element 124 retains the disc element 124 , the ball 123 and the first spring element in the first passage 26 of the tubular member 11 . By using the disc element 124 and the second spring element 125 , the tubular member 11 may be fixed in the chamber 21 . Thereafter, by way of the screw element 22 received in the chamber 21 opposite to the output pipe 20 A, the tubular member 11 is enclosed in the chamber 21 , such that the front end 11 A of the tubular member 11 is matingly engaged with the screw element 22 by using the resilience of the second spring element 125 through the disc element 124 . The sealing sleeve 111 corresponds to an air opening 23 of the chamber 21 , and the ball 123 abuts against the disc element 124 by the first spring element 122 for achieving a checking purpose (as illustrated in FIG. 5 ). The air opening 23 extends perpendicular to the movement direction and has an axial extent in the movement direction less than the sealing sleeve 11 .

In operation, the pump 2 is compressed by inputted air to actuate a piston so as to generate an internal pressure for being inputted into the chamber 21 through the output pipe 20 A. Hence, air pressure may pass through the disc element 124 to push the ball 123 away (as shown in FIG. 6 , the air pressure is greater than the resilience of the first spring element 122 ). Thereafter, the air pressure may further pass through the cap member 121 and the tubular member 11 to lead into the tank of the cylinder 3 for auxiliary pressure by using the pipe 20 B, such that the jack lifts an object (as illustrated in FIG. 8 ). On the contrary, if desiring to lower the object, the pressure in the jack is released, and the air release switch of the jack is turned on for returning air back to the chamber 21 . Since the air pressure is pressed with respect to the front end of the tubular member 11 (as illustrated in FIG. 7 ), and the ball 123 and the disc member 124 in the tubular member 11 form a checking effect, the air pressure pushes the tubular member 11 to move, pressing against the second spring element 125 . The tubular member 11 disengages from the air opening 23 , and air pressure vents from the air opening 23 for a quick pressure releasing purpose. Thereafter, the second spring element 125 biases the tubular member 11 to return to the initial position, such that the air opening 23 may be sealed once more, thereby preventing the hydraulic oil from leakage during the accelerated operation of the jack.

Furthermore, the sealing sleeve 111 may include integrally formed and radially enlarged bulges 111 A and 111 E spaced in the movement direction and arranged at two ends thereof for providing a preferred engagement in response to the chamber 21 . The air opening 23 is located intermediate the radially enlarged bulges 111 A and 111 B when the tubular member 11 abuts with the hollow screw element 22 .

Likewise, the tubular member 11 may include one or more ring elements 113 directly disposed on the exterior thereof for obtaining the sealing purpose relative to the chamber 21 (as shown in FIG. 9 ). Thus, the sealing sleeve 111 may be replaced by the ring element 113 , thus saving the production cost.

The invention is not limited to the above embodiment but various modifications thereof may be made. It will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope and spirit of the present invention.