US3555971A

US3555971A - High pressure lift device for power vehicles and the like

Info

Publication number: US3555971A
Application number: US749698A
Authority: US
Inventors: Hermann Schroder
Original assignee: MESSRS MARKISCHES WERK GmbH
Current assignee: MESSRS MARKISCHES WERK GmbH
Priority date: 1967-08-12
Filing date: 1968-08-02
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19
Also published as: DE1756579A1; DE1756579B2

Abstract

Equipment for the release of air pressure from the high pressure cylinder of a hydraulic lift system is disclosed with use of a restricted passageway permitting air to escape but retaining sufficient pressure from hydraulic fluid to effectively bleed only the air from the system automatically.

Description

United States Patent Inventor Appl. No. Filed Patented Assignee Priority Hermann Schroder Halver, Westphalia, Germany 749,698

Aug. 2, 1968 Jan. 19, 1971 Messrs, Markisches Werk Gesellschaft mit beschrankter Haftung Halver, Westphalia, Germany a corporation of Germany Aug. 12, 1968 Germany HIGH PRESSURE LIFT DEVICE FOR POWER VEHICLES AND THE LIKE 6 Claims, 4 Drawing Figs.

US. Cl 92/113,

1 91/4, 91/422 Int. Cl F011 11/02 Field of Search ..91/(lnquired),

Primary Examiner-Martin P. Schwadron Assistant Examiner-Leslie J Payne Attorney-Laurence R. Brown ABSTRACT: Equipment for the release of air pressure from the high pressure cylinder of a hydraulic lift system is disclosed with use of a restricted passageway permitting air to escape but retaining sufficient pressure from hydraulic fluid to l 15: 254/ 93 effectively bleed only the air from the system automatically.

. h k 11 I I T 17 11. i I 19 1s 2n 1 i 18 l a 21 l r i l a 1 g l 12 l I i l urr nEv rcE roR POWER vErncLEs This invention relates to high pressure lift devices for .powered vehicles. having an outer fixed housing enclosing a guide tube closed by a capping plate'and coaxially arranged about a high lift chamber. The inventionis directed to the problem in high pressure lift devices of this type in Creating an arrangement for releasing air from the high. pressure system. The solution of this problem is therefore characterized by improving the 'arrangement 1 of the main shaft so that it is removably attached' 'onthe capping'plate of the guide tube which has a piston with an air discharge port at its upper end, thereby providing a solution for the problem of high pressure at the'capping plate by permitting the pressure chamber.

In spite of the improvement in function afforded by the high pressure head ar'rangementand the main shaft conforming with thesense of theinvention to produce an air discharge attachment, it can be produced at smallexpense, and simply made. In other embodiments of the invention, the air discharge apparatus may be affordedin a manner that the mouth of the air discharge porti s exhibited in a section of unrestricted air discharge except for building such pressure for hydraulic fluid that the'piston maybe driven by this pressure to a position at the cap plate to automatically discharge the air pressure. Accordingly the high pressure cylinder may be separated from the cap'plate of the guide tube to prevent the cylinder from impacting at its limitingpo'sition; Also it is possible to discharge the escape'ports in the guide tube. Only a little hydraulic fluid is lost through the air pressure releasesystem and it does not harm if discharged in the guide tube.

In another embodiment a discharge-port may be axially bored in the piston head which isthreaded to receive a head bolt mating in an aperture in the guide tube cap plate, where a lateral bore in the piston walls leads to that in the head bolt to let air flow freely, with such spacing that the opening'lies in he high pressure cylinder while the head bolt unites the piston and the cap plate; A second somewhat simpler embodiment of the air discharge apparatus is characterized in that an appendage head on the piston mates with a bore in the cap plate and is removably attached therewith by a spring or the like, and an escape port for airlis located on the appendage.

Further examples and objects of the invention are found in the following description, drawing and claims, wherein 2 top of piston head a leading into the borehole cavity 15b. A lateral bore 15cleads through the wallof piston 15 into the 'cavity 15b. Similarly in the shaft end of headbolt 23 is a cavity bore 23a leading into a lateral bore 23b out of the side.

The bores 15c/15b/23u/23b comprise in their working position the air discharge port. For this reason bore 23b is narrow,

so that escaping air is unrestricted but when hydraulic oil is encountered, offers resistance to provide a restriction so that the piston can be lifted with appropriate restraint.

. The discharge apparatus operates in the following manner: As shown in FIG. 1, the head bolt 23 is screwed out of threaded bushing 24 to extend out of cavity 15b enough that the head bolt has its bottom brought near the indentation 22b in capplate 22. The piston 15 is then touching cap plate 22 and joins guide tube 13. Now the high pressure extending in the cylindrical cavity 26 between piston 15 and pressure cylinder 12 must be withdrawn, as in FIG. 1 by headbolt 23 being unscrewed far enough that in the .FIG. 2'position 15 drops mouth 150 of the air escape port into the high pressure cavity 26, that is beneath the sealing means of steel ring 21. In order for piston 15 to pass to a limiting impact position (not shown) in high pressure cylinder 12, an appropriate pipe or rod is provided in the lower position. When the piston is in the FIG. 1 shows the upper portion of a first embodiment in partial elevation cross section without the framework of the high pressure driving system, which shows the retaining "bolt holding the piston movably in placewith the cap plate of the guide tube,

FIG. 2 is a similar embodiment with the; piston in a lowered air pressure release position,

FIGS. 3 and 4 show similarly to FIGSQI and 2 a second example of an air escape mechanism for high pressure hydraulic piston systems. I i

In the first embodiment of FIGS. 1 and 2, is shown a housing tube 11 that comprises the main cavity of the lifting device. The bottom of this housing tube is not shown. Inside this the high pressure cylinder 12 is mounted. Accordingly the guide tube 13 (partly shown) engages the interior of housing tube 11 through guide ring 14. The piston shaft l5 works together with the high pressure cylinder 12. To guide and seal the cylinder 12, the cylinder head 16 is threaded at the upper end of the high pressure cylinder 12, and confines two

brass rings

17 and 18 on opposite sides of packing sleeve 19 and a steel ring 20, at the bottom end of which is another steel ring 21. The

steel rings

20 and 21 serve to absorb the impact when the pressure of the piston 15 engages cylinderhead l6'(a,t 21). The guide tube 13 is closed by capping plate 22 which is affixed'in aperture 13a. The piston 15 lies beneaththe cap plate 22 in the driven position of the head 15a (FIG. '1).

In order for piston 15 to mate with capplate 22 in closing position, the cap plate 22 has a bore 22a through which the shaft of a threaded head bolt 23 extends. The head bolt 23is screwed into threaded bushing 24, whichis threaded into the discharge position of FIG. 2, hydraulic fluid can be passed through hydraulic line fittings 25, 25(whi'ch are shown in part and lead to hydraulic'means at the bottom of the high pressure cylinder). If air is now found in high pressure chamber 26, it

can flow by way of 15c of the discharge port through 15b, 23a and 23b until it escapes. When the chamber 26 is fully purged of air, oil enters thedischarge port system 15c/l5b/23a/23b. The bore 23b is not so narrow as to prevent escape of oil, but the pressure begins to build in chamber 26 strong enough to push piston l5, which moves mouth 15c past the

sealing rings

21, 18 and so forth. This closes the escape port and the little oil that escapes from 23bremainsin the inside of guide tube 13, where it does no harm. Also it is possible that further will extend piston 15 so far that it will strike cap plate 22 of the guide tube 13 with the head section 15a to attain a lower position than in FIGS. 1 and 2. The head bolt for this reason is unscrewed so far at the lower position that its head is at the bot tom'of depression 22b and the piston 15 is held in the guide tube 13.

In the second embodiment of FIGS. 3 and 4, the apparatus for allowing air to escape from the pressure cylinder is simpler to construct. Similar reference characters are used as in FIGS. 1 and 2 for the corresponding parts. The fastening of the piston 15 on the guide tube cap plate 22 is simpler, since on dage l50a'removably in aperture 220b, disengages the valve of the piston system opens and the 'piston 15 lowers into cylinder 12 where it is halted as in the first example by a not shown stop at the lower end position shown in FIG. 4. FIG. 3

shows the restraining drive position where piston 15 contacts guide cylinder 13.

For purposes of releasing air from pressure chamber 26, head 15a of the piston 15 has from theend a bore 15% parallel with the axis and a lateral bore C which ends at the periphery of the piston. The end of bore 150b in appendage 150a is closed by a plug 151. A very thin lateral bore 150d leads normally from bore 15% to the side of appendage 150a.

The system of connecting ports l50c/l50b/ 150d is so oriented that in the drive position ofFIG. 3 the opening-150c lies above the sealing ring'19, while in the air releasing lower position of piston 15(FIG. 4) the opening l50c leads to pressure chamber 26, where in the same manner as described for the first embodiment, the narrow bore'150d opens in the inside of guide cylinder 13, where the escaping air and the following hydraulic fluid can attain atmospheric pressure.

The operationof the apparatus of FIGS. 3 and 4 is similar to thatdescribed for FIGS. 1 and 2.

'Iclaim:

I. High pressure lift means for powered vehicles and the like which have a guide tube closed by a cap plate and an outer housing coaxially arranged about the guide tube and an inner high pressure chamber coaxially arranged therein with a piston movable in said high pressure chamber comprising in combination, closure means on the upper end of the piston removably positioning an air discharge port through said do sure means with an opening movable into and out of the high pressure chamber to release air therethrough when said opening is moved into the high pressure.

2. Means defined in claim 1 wherein the discharge port has a restricted dimension providing substantially unresisted passage of air but providing substantial pressure resisting the passage of hydraulic fluid.

3. Means defined in claim 1 wherein the piston in one limiting position contacts the cap plate.

4. Means defined in claim 1 wherein the discharge port has an outlet in the guide tube.

5. Apparatus defined in claim 1 wherein the piston has on one end an axial bore, the cap plate has an aperture, and means comprising a threaded bolt with an air discharge port therein coupling said piston cap plate.

6. Apparatus defined in claim 1 wherein the piston has on one end an appendage with an axial bore therethrough, the cap plate has a mating aperture receiving said appendage, and a spring holds said appendage removably in said aperture.

Claims

1. High pressure lift means for powered vehicles and the like which have a guide tube closed by a cap plate and an outer housing coaxially arranged about the guide tube and an inner high pressure chamber coaxially arranged therein with a piston movable in said high pressure chamber comprising in combination, closure means on the upper end of the piston removably positioning an air discharge port through said closure means with an opening movable into and out of the high pressure chamber to release air therethrough when said opening is moved into the high pressure.