US3615157A - Hydraulic jack - Google Patents

Abstract

THERE IS HEREIN DISCLOSED A HYDRAULIC JACK FOR USE WITH AUTOMOBILES OR THE LIKE, HAVING A PUMP HANDLE CONNECTED TO A PISTON FOR PUMPING HYDRAULIC FLUID FROM A RESERVOIR TO A LIFTING CYLINDER. THE LIFTING CYLINDER SURROUNDS A STATIONARY, GROUND SUPPORTED PISTON AND CARRIES A HOOK FOR CONNECTION TO AN AUTOMOBILE BUMPER OR THE LIKE.

Description

1971 L. D'AMICQTROTTAI I 3, 1

HYDRAULIC JACK 2 Sheets-Sheet 1 Filed Jan. 23, 1969 INVENTOR. Zzzz'yz' 2772mm 7/7274 BY j I) United States Patent O 3,615,157 HYDRAULIC JACK Luigi DAmico Trotta, Caracas, Venezuela, assignor to Multipreus, C.A., Caracas, Venezuela Filed Jan. 23, 1969, Ser. No. 793,277 Claims priority, application Venezuela, Mar. 7, 1968,

Int. Cl. B66f 3/24 U.S. Cl. 254-93 H 3 Claims ABSTRACT OF THE DISCLOSURE There is herein disclosed a hydraulic jack for use with automobiles or the like, having a pump handle connected to a piston for pumping hydraulic fluid from a reservoir to a lifting cylinder. The lifting cylinder surrounds a stationary, ground supported piston and carries a hook for connection to an automobile bumper or the like.

SUMMARY OF THE INVENTION This invention relates generally to lifting devices and, more particularly, to a new and improved hydraulic jack which consists of a minimum number of parts so as to give the device a design which is compact in nature and highly reliable in operation.

This and other objects are accomplished in a construction which is so reduced in the number and character of its component parts so as to approach the ultimate in structural simplicity to thereby create an economy in its manufacture, installation and maintenance. The device includes a piston housing which is spacedly surrounded by a wall to define an annular-shaped fluid reservoir therebetween. A piston is reciproeated within a bore of the housing to draw fluid from the reservoir and deliver it to a lifting cylinder. The opposite ends of the housing are provided with flanges that are sealed with respect to the reservoir wall by conventional O-rings.

(Passages exist between the housing and the reservoir and between the housing and the lifting cylinder. A pair of check valves control the flow of fluid through the passages. Reciprocation of the piston is accomplished by a conventional pump handle. When the handle and piston are raised, fluid is drawn from the reservoir past a first check valve to fill the piston bore in the housing. At this time the second check valve remains closed. Downward movement of the handle will cause the piston to displace fluid past the second check valve to the lifting cylinder. At this time the first check valve remains closed. Downward movement of the handle is yieldably resisted toward the end of its stroke by a spring. In pumping up the lifting cylinder, downward movement of the handle is stopped when the spring is encountered. Further downward movement of the handle against the spring is operable to relieve pressure in the lifting chamber and permit return flow of fluid to the reservoir. This function results from the provision of a special valve displacing element on the piston which will unseat the balls of both check valves.

The formation and location of the reservoir in the foregoing manner renders the unit highly compact, minimizes the danger of damages to the reservoir defining wall, simplifies the formation of connecting passages between the reservoir and housing, enables the housing to be inexpensively machined in two parts and reduces other manufacturing costs.

Patented Oct. 26, 1971 The structure of the present invention also eliminates a separate pressure relief valve by use of a valve displacement member on the pumping piston. This valve displacement member also greatly simplifies the lowering of the jack.

The various objects and advantages and the novel details of construction of one commercially practical embodiment of the invention will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view, with parts broken away, of a preferred embodiment of the present invention;

FIG. 2 is an enlarged sectional view of the structure illustrated in FIG. 1, taken substantially along the line 22 thereof;

FIG. 3 is an enlarged vertical sectional view of a portion of the structure depicted in FIG. 1; and

FIG. 4 is a view of the structure illustrated in FIG. 3, showing another position of the parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a hydraulic jack made in accordance with the present invention is illustrated as having a two-part pump housing 10 surrounded by a reservoir member 12, a pump handle 14 mounted on the reservoir member 12 and a lifting cylinder 16 on which the reservoir member is mounted. A bracket 18 is adjustably secured on the lifting cylinder 16 which surrounds and is telescopically fitted on a supporting post 20 having a ground supported base 22 at its lower end. The hydraulic jack illustrated herein is primarily intended for use with an automobile for lifting one end of the automobile to change a flat tire. For this purpose, the base 22 is positioned on the ground with the lifting cylinder in a vertical attitude. The pump handle 14 is manually reciprocated to pump hydraulic fluid to the lifting cylinder 16. This produces vertical movement of the lifting cylinder with respect to the supporting post 20. The vehicle to be lifted is connected to the bracket 18 so that the elevation of the lifting cylinder will lift the vehicle.

Referring now to FIGS. 3 and 4, the construction of the pump housing 10 and its associated parts are illustrated in detail. The housing 10 includes an elongated generally cylindrical housing member 10A and a smaller externally threaded housing member 10B. The housing member 103 is particularly suited for high production manufacture on automatic screw machines, or the like. The housing member 10A is formed with a cylindrical bore 24- extending from one end thereof to the other. A threaded counterbore 26 is located at the lower end of the bore 24, while a radially outwardly extending annular flange 28 is formed at the upper end of the housing member 10A. The housing member 10B has an externally threaded portion 30 which is threaded into the counterbore 26 to join the housing members 10A and 10B together.

The housing member 10B has a threaded portion 31 formed at its lower end which is threaded into the upper end of the lifting cylinder 16. A radially outwardly extending annular flange 32 is provided on the housing member 103 between the threaded portions 30 and 31 thereof. An axially extending bore 34 extends through the housing member 10B in axial alignment with the bore 24. The

bore 34 is formed with a counterbore 36 at its upper end and a counterbore 38 at its lower end. A recess 40 is formed in the housing portion 30 and projects from one side of the counterbore 36, while a passage 42 in the housing portion 31 provides communication between the recess 40 and the outer periphery of the housing member B in a location beneath the housing member 10A.

It will be seen that the reservoir member 12 surrounds the housing 10 to define a generally annular reservoir 44 therebetween. This is accomplished by the formation of radially inturned annular walls 46 which are located at the opposite ends of the reservoir member 12 and have axially aligned openings 48. The housing 10 extends axially between the two openings 48 with the flanges 28 and 32 being engageable with the outer sides of the walls 46 in locations surrounding the openings 48. O-rings 50 are positioned at such locations to provide a fluid-tight seal between the housing 10 and the reservoir member 12. The reservoir 44 is filled with hydraulic fluid through an opening 49 in the member 12 which is normally closed by a rubber plug 51. From the reservoir 44 fluid flows through the passage 42 to the pocket 40 and counterbore 36, as well as to the lower end of the bore 24. From this location hydraulic fluid is pumped downwardly by a piston 52 which is slidably disposed within the cylinder bore 24. The piston 52 carries a lip seal 54 and has a reduced diameter portion 56 depending from its lower end into the bore 34. The piston portion 56 is of sufficiently smaller diameter than the bore 34 to permit fluid to flow freely around it in the bore 34. The piston 52 has a conical shoulder 58 disposed immediately above the reduced diameter portion 56.

The piston 52 is designed to be reciprocated by the handle 14 which is secured to a fitting 60. The fitting 60 is piovtally connected to the upper end of the piston 52 and to a link 62 which is pivotally mounted on a boss 64 welded to the outer surface of the reservoir member 12. The fitting 60 is engageable with a spring 66 surrounding the piston 52 and seated against the upper end of the housing member 10A. The handle 14 is intended to be moved downwardly in a pumping stroke until the fitting 60 engages the spring 66, which yieldably resists further downward movement of the handle. The handle 10 is then lifted for another pumping stroke.

In order for the pumping movement of the piston 52 to effect lifting movement of the cylinder 16, a pair of check valves are required. One of said check valves comprises a ball 68 positioned in the pocket 40 and adapted to seat against an annular valve seat 70 surrounding one end of the passage 42. The second check valve comprises a ball 72 disposed in the counterbore 38 and engageable with an annular valve seat 74 formed around one end of the bore 34. The ball 72 is normally urged into contact with the valve seat 74 by a spring 76 which is seated within a groove 78 of the bore 38. During the upward movement of the handle 14, the ball 72 will be held closed while the ball 68 will be drawn upwardly by a sucking or vacuum action of the piston 52. This permits fluid to flow from the reservoir 44 through the passage 42 into the counterbore 38 in the lower end of the bore 24. As the piston 52 begins its downward stroke, the pressure which it creates will cause the ball 68 to close against its seat 70 while the resulting pressure of fluid within the bore 34 will displace the ball 72 from its seat, permitting fluid to flow past the ball 72 to an expansion chamber 80 formed within the lifting cylinder 16.

As the lifting cylinder 16 rises, it movement is guided by a guide member 82 of a generally flanged sleeve shape secured to the lower end of the lifting cylinder 16. The lifting cylinder is also guided by a piston 84 fixed to the upper end of the stationary post and smoothly and glidably engaging the inner peripheral surface of the lifting cylinder 16. The piston 84 is fitted with an O-ring 86 and a lip seal 88 which prevents the downward flow of fluid out of the expansion chamber 80.

A mechanical connection between the lifting cylinder 16 and the automobile to be lifted is achieved by means including the bracket 18. Referring to FIGS. 1 and 2, it will be seen that the bracket 18 is provided with a pair of spaced ears 87 on one side thereof. A threaded stud 89 passes freely through one of the ears 87 and is threaded into the other of said ears. The stud 89 is formed with an integral shouldered handle portion 90 by which the stud may be rotated to draw the ears 87 together. This causes a central apertured portion 92 of the bracket 18, surrounding the lifting cylinder to be clamped in a given position on the lifting cylinder 16. Accordingly, the bracket 18 may be moved to any desired vertical position on the lifting cylinder 16 On the side of the bracket 16 opposite from the ears 87, a pair of ears 94 are formed with a pin 96 extending therebetween. A chain 98 is hung from the pin 96 and carries a hook 100 at its lower end. The hook 100 is fitted under the bumper of the automobile to be lifted or in any other desired location on the automobile. It will be appreciated that be simply loosening the stud 89 and positioning the hook 100 as desired, the jack can be immediately positioned so that pumping of the handle 14 will effect immedaite lifting of the automobile.

The various positions of the check valve balls 68 and 72 during various phases of the pumping cycle are illustrated in FIGS. 3 and 4. FIG. 3 illustrates the return stroke of the piston 52 in which the ball 68 is drawn upwardly off of its seat but with the ball 72 being in the closed position. FIG. 4 illustrates a further position of the piston 52 in which the downward movement of the piston 52 has been completed and wherein the handle is pushed downwardly against the spring 66 to cause the reduced diameter portion 56 of the piston to contact the ball 72 and physically displace it downwardly away from its seat 74. The relative spacing between the lower end of piston portion 56 and the piston shoulder 58 is such that when the piston portion 56 unseats the ball 72, the conical shoulder 58 will also unseat the ball 68 from its seat by a sideways wedging movement. Accordingly, the full downward movement of the handle 14 against the spring 66 will unseat both the check valves and thereby permit a free return flow of fluid from the expansion chamber 80 to the reservoir 44. This, of course, lowers the jack. The power for producing such return flow is supplied by the weight of the vehicle.

The jack of the present invention preferably incorporates means to prevent damage to the parts from continued pumping after the lifting cylinder 16 has been fully raised. This means comprises a lead filled hole 102 in the wall of the cylinder 116 which rises above the seal 88 only at the end of the upward movement of the cylinder 16. If the fluid in the cylinder 16 is excessively pressurized with the lifting cylinder in this position, it will force the lead out of the hole 10 and provide a vent for fluid to escape onto the ground. It should be mentioned, however, that the need for this is rather unlikely and the hydraulic fluid is normally contained in a closed system.

From the foregoing, it will be appreciated that the location of the reservoir 44 annularly about the pump housing 10 renders the entire structure highly compact, mini mizes the danger of damage to the reservoir, and reduces the cost of manufacture of the product. In particular, reservoir member 12 can be relatively inexpensively fabricated compared to a sheet metal member which forms the entire enclosure for the reservoir. The utilization of the housing flanges 28 and 32 to close the reservoir takes advantage of the existing housing structure in order to complete the formation of the reservoir at a minimum of expense. Also, the formation of the housing 10 in two parts facilitates the assembly of the device and makes it extremely easy to unite the housing with the lifting cylinder 16. Of course the reduced diameter piston portion 56 and the conical shoulder 58 eliminate the necessity of a third pressure relief valve and render the lowering of the jack highly convenient.

I claim:

1. A hydraulic jack comprising:

a housing defining a bore,

a pump piston disposed within said bore,

a fluid reservoir,

first passage means providing communication from said reservoir to said bore,

a lifting cylinder,

second passage means providing communication from said bore to said lifting cylinder,

a first check valve operable to close said first passage means when said piston is in its pumping stroke,

a. second check valve normally closing said second passage means but operable in response to pumping movement of said piston, and

means on said piston for simultaneously displacin and opening said first and second check valves when said piston is moved to a given position.

2. The invention as set forth in claim 1 wherein said second check valve is a spring biased ball.

3. The invention as set forth in claim 1 wherein said first check valve is a ball and said means on said piston includes a conical shoulder operable to displace said ball laterally of the direction of piston movement.

References Cited UNITED STATES PATENTS 2,498,698 2/1950 Mueller 6052 2,505,187 4/1950 Jurgens 25493 X 2,527,841 10/1950 Mueller 254-93 2,544,039 3/1951 Pearne 25493 2,557,880 6/1951 Lynn 6052 X 3,266,773 8/1966 Cole 254133 X 3,355,147 11/1967 Gormley 6052 X 3,464,204 9/1969 Rudkin 6052 ROBERT C. RIORDON, Primary Examiner D. R. MELTON, Assistant Examiner U. S. Cl. X.R. 6052 HA

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