Abstract:
A pneumatically driven hydraulic pump in accordance with the present invention is comprised of a cylindrical body, a front end cap, a rear end cap, a division wall, a piston, a control valve, a pneumatic valve, an air bladder and a pedal. The pneumatically piston and the air bladder also connected to the air source are used to quickly pump hydraulic fluid to an external hydraulic lifting device. Consequently, a heavy object can be lifted or lowered quickly.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is related to a pump, and more particularly to a pneumatically driven hydraulic pump.  
           [0003]    2. Description of Related Art  
           [0004]    In some lifting devices such as jacks for raising heavy objects, hydraulic mechanisms are generally used as driving devices to lift the heavy objects because they have characteristics of stability and high load-bearing capability. To operate, the hydraulic mechanism must be filled with hydraulic fluid or another liquid. If the lifting device has a very long lifting distance, it is very slow and inconvenient to manually fill with hydraulic fluid. Thus, pneumatically driven hydraulic pumps have been invented for pumping hydraulic fluid into the hydraulic lifting mechanism.  
           [0005]    A conventional pneumatically driven hydraulic pump has a cylindrical body with a center, two ends, a top, a bottom and two sides. A division wall at the center of the cylindrical body divides the cylindrical body into a piston chamber and a hydraulic fluid reservoir at opposite ends of the cylindrical body. A piston is movably mounted in the piston chamber, and hydraulic fluid is stored in the hydraulic fluid reservoir. A pedal is pivotally mounted on the top of the cylindrical body.  
           [0006]    A hydraulic fluid discharge passage composed of a lower channel, an upright channel, an inclined channel and an upper channel is defined in the division wall and communicates with the hydraulic fluid reservoir through the lower channel and the piston chamber through the inclined channel.  
           [0007]    A check valve and a control valve are mounted in the division wall. The check valve is mounted in the upright channel of the hydraulic fluid discharge passage near the piston. The control valve communicates with the upper channel of the hydraulic fluid discharge passage near the hydraulic fluid reservoir, extends out from the top of the cylindrical body and abuts a first end of the pedal. A hydraulic fluid discharge connector is mounted on one side of the cylindrical body, and a hydraulic fluid discharge port is defined in the discharge connector and communicates with the upper channel of the hydraulic fluid discharge passage. A hydraulic fluid return passage is defined in an upper portion of the division wall and communicates with the upper channel through the control valve.  
           [0008]    A pneumatic valve is formed in a cap at the end of the cylindrical body adjacent to the piston and is controlled by a second end of the pedal.  
           [0009]    When operating the pump, the second end of the pedal opens the pneumatic valve when it pivots down, and the piston is driven in a reciprocating manner. The piston pumps hydraulic fluid from the hydraulic fluid reservoir into the hydraulic fluid discharge passage through the check valve and out through the hydraulic fluid discharge port of the hydraulic fluid discharge connector. The hydraulic fluid under pressure fills an external hydraulic mechanism for lifting a heavy object. In this case, the control valve is closed, and hydraulic fluid cannot flow back into the hydraulic fluid reservoir.  
           [0010]    When the first end of the pedal is pivoted downward and presses the control valve down, the control valve is opened and the pneumatic valve is closed. The piston stops, and hydraulic fluid in the external hydraulic mechanism flows through the hydraulic fluid discharge port, the control valve and the hydraulic fluid return passage to the hydraulic fluid reservoir.  
           [0011]    Hydraulic fluid pumped by a single stroke of the piston is small, and objects are lifted slowly. Even when pressure of air supplied to the pneumatic valve is increased, the output of hydraulic fluid is still limited. Thus, a very long time is required to lift an object when using this type of pneumatically driven hydraulic pump.  
           [0012]    Therefore, the invention provides to an improved pneumatically driven hydraulic pump to mitigate and/or obviate the aforementioned problems.  
         SUMMARY OF THE INVENTION  
         [0013]    The main objective of the invention is to provide a pneumatically driven hydraulic pump that can quickly pump hydraulic fluid into an external hydraulic mechanism for lifting a heavy object.  
           [0014]    Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a perspective view of a pneumatically driven hydraulic pump in accordance with the invention;  
         [0016]    [0016]FIG. 2 is a cross sectional left side view of the pneumatically driven hydraulic pump in FIG. 1;  
         [0017]    [0017]FIG. 3 is a cross sectional top view of the pneumatically driven hydraulic pump in FIG. 1;  
         [0018]    [0018]FIG. 4 is a cross sectional end view of the pneumatically driven hydraulic pump along line “ 4 - 4 ” in FIG. 3;  
         [0019]    [0019]FIG. 5 is a cross sectional end view of the pneumatically driven hydraulic pump along the line “ 5 - 5 ” in FIG. 3;  
         [0020]    [0020]FIG. 6 is an operational cross sectional left side view showing hydraulic fluid flowing out of the pump; and  
         [0021]    [0021]FIG. 7 is an operational cross sectional left side view showing hydraulic fluid flowing back into the pump. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    With reference to FIGS.  1 - 3 , a pneumatically driven hydraulic pump in accordance with the present invention comprises a cylindrical body ( 10 ), a front end cap ( 101 ), a rear end cap ( 102 ), a division wall ( 12 ), a piston ( 17 ), a control valve ( 153 ), a pneumatic valve ( 165 ), an air bladder ( 18 ) and a pedal ( 11 ). The cylindrical body ( 10 ) has a center, a front end, a rear end, a top, a bottom and two sides. The pedal ( 11 ) is pivotally mounted on the top of the cylindrical body ( 10 ) to control the discharge or intake of hydraulic fluid ( 141 ).  
         [0023]    The division wall ( 12 ) with an upper portion, a central portion, a lower portion and a front and rear side is mounted at the center of the cylindrical body ( 10 ) to form a piston chamber ( 13 ) and a hydraulic fluid reservoir ( 14 ) inside the cylindrical body ( 10 ) respectively at rear and front sides of the division wall ( 12 ). The piston ( 17 ) is longitudinally movably mounted in the piston chamber ( 13 ), and the hydraulic fluid reservoir ( 14 ) is filled with hydraulic fluid ( 141 ).  
         [0024]    A hydraulic fluid discharge passage ( 15 ) composed of a lower channel, an upright channel, an inclined channel and an upper channel is defined in the division wall ( 12 ). The lower channel has an exterior end and an interior end and communicates with the hydraulic fluid reservoir ( 14 ) through a hydraulic fluid discharge opening ( 151 ) at the exterior end of the lower channel. The inclined channel communicates with the piston chamber ( 13 ). A check valve (not numbered) is mounted in the upright channel and has a first ball beneath the inclined channel and a second ball above the inclined channel. The control valve ( 153 ) is uprightly provided in the division wall ( 12 ) and extends out from the top of the cylindrical body ( 10 ) to abut a first end of the pedal ( 11 ). A hydraulic fluid return passage ( 154 ) is defined in the upper portion of the division wall ( 12 ) and communicates with the upper channel of the hydraulic fluid discharge passage ( 15 ) through the control valve ( 153 ).  
         [0025]    With reference to FIGS. 4 and 5, a connector (not numbered) is mounted at a side of the cylindrical body ( 10 ), and a hydraulic fluid output ( 152 ) is defined in the connector in communication with the upper channel of the hydraulic fluid discharge passage ( 15 ). Hydraulic fluid ( 141 ) in the hydraulic fluid reservoir ( 14 ) can flow through the hydraulic fluid discharge opening ( 151 ), the hydraulic fluid discharge passage ( 15 ) and the hydraulic fluid discharge port ( 152 ) to an external hydraulic mechanism (not shown) connected to the pump at the connector.  
         [0026]    With reference to FIGS.  1 - 3 , the rear-end cap ( 102 ) has an inside and outside surface and is attached to the rear end of the cylindrical body ( 10 ) to enclose the piston chamber ( 13 ). An air passage ( 16 ) is defined vertically in the rear-end cap ( 102 ). From bottom to top on the rear-end cap ( 102 ), an air inlet ( 161 ), an air discharge port ( 162 ) and an air vent ( 163 ) are in turn defined between the outside surface of the rear-end cap ( 102 ) and the air passage ( 16 ). An air supply (not shown or numbered) is connected to the air inlet ( 161 ). An air port ( 164 ) is defined on the inside surface of the rear-end cap ( 102 ) to communicate between the air passage ( 16 ) and the piston chamber ( 13 ).  
         [0027]    The pneumatic valve ( 165 ) is mounted in the air passage ( 16 ) and has a valve stem ( 166 ) with an upper end and a lower end slidably mounted in the air passage ( 16 ) and a resilient member ( 167 ) mounted in the air passage ( 16 ) at the lower end of the valve stem ( 166 ). The upper end of the valve stem ( 166 ) extends out from the air passage ( 16 ) and abuts a second end of the pedal ( 11 ).  
         [0028]    The piston ( 17 ) has a piston rod ( 171 ) extending in a central channel (not numbered) of a piston seat (not numbered) beside the division wall ( 12 ), and a piston spring ( 172 ) provided outside the piston rod ( 171 ). The central channel communicates with the inclined channel of the hydraulic fluid discharge passage ( 15 ).  
         [0029]    The front-end cap ( 101 ) is mounted on the front end of the cylindrical body ( 10 ) to close the hydraulic fluid reservoir ( 14 ). An air bladder ( 18 ) is mounted on the front-end cap ( 101 ) inside the hydraulic fluid reservoir ( 14 ). The hydraulic fluid ( 141 ) in the hydraulic fluid reservoir ( 14 ) is outside the air bladder ( 18 ). The air bladder ( 18 ) communicates with the air discharge port ( 162 ) through a tube ( 19 ) and a joint (not numbered) on the front-end cap ( 101 ).  
         [0030]    With reference to FIG. 6, the air inlet ( 161 ) is opened when a second end of the pedal ( 11 ) is pivoted down to press the valve stem ( 166 ), and the air vent ( 163 ) is closed. High-pressure air flows into the air passage ( 16 ) and through the air port ( 164 ) into the piston chamber ( 13 ) and through the air discharge port ( 162 ) and the tube ( 19 ) into the air bladder ( 18 ). The high-pressure air flowing into the piston chamber ( 13 ) causes the piston ( 17 ) to reciprocate. The hydraulic fluid ( 141 ) in the hydraulic fluid reservoir ( 14 ) is pumped by the piston ( 17 ) into the hydraulic fluid discharge passage ( 15 ) and flows out from the hydraulic fluid discharge port ( 152 ) to the external hydraulic mechanism. The air bladder ( 18 ) is inflated by the high-pressure air through the tube ( 19 ), and the hydraulic fluid ( 141 ) in the hydraulic fluid reservoir ( 14 ) is further expelled by the inflated bladder ( 18 ) into the hydraulic fluid discharge passage ( 15 ). Therefore, by means of the pumping action of the piston ( 17 ) and the expulsion action of the bladder ( 18 ), a large amount of hydraulic fluid ( 141 ) is caused to flow through the hydraulic fluid discharge passage ( 15 ) and the hydraulic fluid discharge port ( 152 ) to the external hydraulic mechanism in a very short time. Therefore, a heavy object can be lifted quickly by the hydraulic mechanism.  
         [0031]    With reference to FIG. 7, the control valve ( 153 ) is pressed down and the valve stem ( 166 ) of the pneumatic valve ( 165 ) is released when the first end of the pedal ( 11 ) is pivoted down. The control valve ( 153 ) opens and the valve stem ( 166 ) of the pneumatic valve ( 165 ) is moved upward by the resilient member ( 167 ), closes the air inlet ( 161 ) and opens the air vent ( 163 ). Air in the piston chamber ( 13 ) flows out through the air vent ( 163 ), and the piston ( 17 ) stops. Air in the bladder ( 18 ) flows out through the tube ( 19 ), the air discharge port ( 162 ) and the air vent ( 163 ), and the air bladder ( 18 ) returns to its original shape. Hydraulic fluid ( 141 ) in the hydraulic mechanism can flow through the hydraulic fluid discharge port ( 152 ), the control valve ( 153 ) and the hydraulic fluid return passage ( 154 ) back to the hydraulic fluid reservoir ( 14 ).  
         [0032]    According to the present invention, the air bladder ( 18 ) in the hydraulic fluid reservoir ( 14 ) of the pneumatically driven hydraulic pump causes a large amount of hydraulic fluid ( 141 ) to rapidly flow to the external hydraulic mechanism connected to the pump so a heavy object is lifted in a short time.  
         [0033]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.