US3593978A

US3593978A - Hydro-pneumatic spring system, especially for motor vehicles

Info

Publication number: US3593978A
Application number: US816344A
Authority: US
Inventors: Manfred Lohr
Original assignee: Hoesch AG
Current assignee: Fried Krupp AG Hoesch Krupp
Priority date: 1968-04-17
Filing date: 1969-04-15
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20
Also published as: GB1261555A; FR1600135A; DE1755237B1

Abstract

A shock absorbing and automatic level control operating cylinder with a hollow piston rod reciprocable therein and having a highpressure storage and an operating chamber. A hollow pump rod is axially movable in said hollow piston and a pump piston is carried by a free end of the hollow pump rod. A valve body is slidably guided with respect to the pump rod and has an abutment engageable upon the pump piston. An insert member has a surface liftable with respect to a valve seat provided by the valve body and a throttle-forming bore means makes possible passage of hydraulic medium from the high-pressure storage into the operating chamber. A preloaded tension spring means presses upon a surface of the insert member for interrupting pump operation. Additional check valves are provided for opening of high-pressure storage and for making possible pump operation.

Description

United States Patent 2/ I 970 Tulzek...

Primary Examiner.lamcs B. Marbert Atwrney walter Becker [72] Inventor ManiredLohr ABSTRACT: A shock absorbing and automatic level control operating cylinder with a hollow piston rod reciprocable therein and having a high-pressure storage and an operating chamber. A hollow p ump rod is axially movable in said hollow piston and a pump piston is carried by a free end of the hollow ESPECIALLY FOR MOTOR VEHICLES 16 Claims, 5 Drawing Figs.

\ pump rod. A valve body is slidably guided with respect to the pump rod and has an abutment engageable upon the pump U-S- piston. Ah insert member has a surface liftable with respect to Ink a valve seat provided by the valve body and a throttle-forming 501 Field ofSearch..................w.r

bore means makes possible passage of hydraulic medium from 8 the high-pressure storage into the operating chamber. A preloaded tension spring means presses upon a surface of the in- [56] References Cited UNITED STATES PATENTS 11/1967 Axthammeretal.........

PATENTFU JUL 20 Ian SHEET 1 BF 5 PATENTED JUL 20 lSil SHIIH u nr 5 FIG. 4

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ATENIH] JUL 2 0 Ian SHEET 5 0F 5 HYDRO-PNEUMATIC SPRING SYSTEM, ESPECIALLY FOR MOTOR VEHICLES The present invention relates to a hydropneumatic spring system with hydraulic damping effect or if desired without a damping effect, and with automatic level control, which spring system will be able to control or stabilize the loads during a standstill and the relief during the drive, especially for motor vehicles, said spring system comprising two separate preloaded gas cushions operable to act upon a hydraulic medium which, by means ofa pumping or control mechanism arranged in a hollow piston rod, is controlled in conformity with the load.

Hydropneumatic spring systems or elements are known by means of which the nominal level of the vehicle is obtained under load only after the vehicle has driven a certain distance, and by means of which when relieved of load the'standing vehicle is brought back to its nominal level. Spring elements or systems of this type have the drawback that when installed on the rear axle, after the vehicle has been loaded, the position of the bright lights will not be correct as long as the vehicle is below the nominal level whereby during night driving the driver of the oncoming vehicle will be blinded. Moreover, with a fully loaded vehicle, the residual travel stroke of the spring is relatively short.

When combining such hydropneumatic spring element with a steel spring, the fully loaded vehicle will at the start of its travelling move along a too soft spring line of characteristic. When driving through a curve or cornering this leads to a transverse tilting of the vehicle.

There has also become known a hydropneumatic spring element which when the vehicle is at a standstill levels or regulates upwardly and when the vehicle is being driven levels out a previously effected relief, which, however, has the drawback that the pumping effect is speed responsive and has no socalled normal range whereby after reaching its level, the pump will not be turned offso that the vehicle carries out a continu' ous upward and downward movement or plays around the nominal level.

Another heretofore known design of the type involved lacks a damping system and practically cannot be realized inasmuch as the spring of the pushrod valve cannot produce the necessary high forces at corresponding spring strokes which are required for the opening of the check valve of the high pressure accumulator when the vehicle is empty.

It is, therefore, an object of the present invention to provide a hydropneumatic spring system which will make it possible that when the standing vehicle is under load the desired level will be reached immediately and when the vehicle is relieved after having driven over a certain distance, the desired level will be reached.

It is another object of this invention to provide a hydropneumatic spring system or spring arrangement as set forth in the preceding paragraph which for avoiding continuous upward leveling and pumping operations will have a normal range.

These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:

FIG. 1 shows a hydropneumatic spring system according to the invention in the pumping range.

FIG. 2 shows the hydropneumatic spring system according to the invention in its normal range.

FIG. 3 illustrates the hydropneumatic spring system according to the invention in its upward-leveled range.

FIG. 4 represents a hydropneumatic spring element according to the invention with a high pressure accumulator above the upper suspension.

FIG. 5 is a hydropneumatic spring system without damping in its normal range.

The hydropneumatic springsystem according to the present invention is characterized primarily in that in the interior ofa hollow piston rod there is axially movably arranged a hollow pump rod the nonclamped-in end of which is provided with a pump piston having axially movably and slidably mounted thereon a valve bodywhich in its upward leveling or upward regulating range hasiits abutment engage the pump piston whereby the valve seat of said valve body is lifted off from a surface of an insert member and through the intervention of a throttle bore, the passage of hydraulic "fluid from a high-pressure accumulator to a working chamber is made possible. When the piston rod moves into this position, the abutment closes the check valve in the pump piston whereby outer influences upon the spring line of characteristic are limited to a minimum. Within the normal range, the valve body is adapted by means of the pressure in the high-pressure accumulator which pressure acts through bores and an annular passage of the pump piston, a longitudinal groove of the valve body and the bores of the abutment upon the valve seat, is pressed upon the surface of the insert member in a sealing manner whereby the pumping effect will be interrupted whereas within the pumping range the valve body operates as suction valve and in cooperation with the check valve in the pump piston makes possible a pumping effect.

By means of a damping piston, a damping effect will be realized which is independent of the respective load or working position of the spring system. This damping effect will in the pulling direction be buffered between fixed walls, whereasthe pressure direction is determined by the pressure of the working chamber and is by means of a valve arranged in the guiding means for the rod limited in such a way that below the damping piston no low pressure will occur.

When installation space is lacking, a particularly advantageous design of the hydropneumatic spring system according to the invention is realized by arranging the high-pressure accumulator for instance in the trunk of the vehicle, said highpressure accumulator being screwed onto an upper suspension system formed by a pin suspension. By means of two check valves which are opened only when screwing on the high-pressure accumulator, the spring element or spring system and the high-pressure accumulator can be filled separately and can be subjected to a corresponding pressure. By means of a pipe of synthetic material, e.g. polyvinylchloride, which pipe may have its upper end designed for instance as a sealing ring, gas and hydraulic liquid are separated from each other in the spring system.

A very simple hydropneumatic spring system without damping is obtained when during the compression of the spring (Einfedem) hydraulic liquid is, by a check valve in the piston, drawn into the space between the piston and the piston rod, which liquid when the piston and piston rod move outwardly is, by lifting off the valve body, pumped into the high-pressure accumulator until the piston ring of the piston moves over a longitudinal groove in the cylinder and thus ends the pumping effect.

Referring now to the drawings in detail, a hydropneumatic spring element or spring system inthe pump range of FIG. 1 is,

' by means of an upper suspension ll, connected to the vehicle body and, by means of a lower suspension 2, is connected to the axle of the vehicle. An outer mantle 3 which at one endis closed by a bottom 4 encloses the hydropneumatic spring system. The bottom 4 is provided with a piston rod seal 5 while a further seal 6 is interposed between the bottom 4 and the outer mantle or jacket 3. A hollow piston rod 7 is adapted to slide in guiding means 8 and is provided with an insert member 9 carrying a damping piston 10 movable in a cylinder 11. An annular chamber I6 is formed by a supporting pipe 12 with openings 13 at the lower end thereof, and by the cylinder 11 with openings 14 at the upper end of said cylinder Ill, said.

upper end resting against a supporting body 15.

A working chamber 17 between an intermediate member 18 and the bottom 4 is subdivided into a working gas chamber 17I and a working fluid chamber 172. The said intermediate member 18 separates the working chamber 17 from a high pressure accumulator 19 which in its turn is subdivided by an elastic separating member 20 into a high-pressure gas chamber 191 and a high-pressure fluid chamber 192. The supporting body is provided with passages 21 and furthermore comprises a pump limiting valve 22 and an elastic suspension 23 of a hollow pump rod 24 the hollow end of which carries a pump piston 25. Piston 25 is provided with

piston rings

26 and 27 which are so arranged that an annular passage 28 is formed thcrebetween which passage through bores 29 communicates with an inner bore 30 of the hollow pump rod 24 and also comprises a check valve 31. The pump piston 25 is slidably guided in a valve body 32 which in its upper end has a valve seat 33 a throttling bore 34 while its lower end is provided with a longitudinal groove 35, an abutment 36, and a closure member 37. The valve body 32 is pressed by a preloaded tension spring 38 against a surface 40 of the insert member 9. The spring 38 is connected for instance to the closure member 37 and is furthermore for instance by a ring 39 connected to the hollow piston rod 7.

When the piston rod 7 moves outwardly, the check valve 31 closes, and hydraulic fluid passes from the working liquid chamber 172 through openings 13, annular chamber 16, and openings 14 into a chamber 41 above the damping piston 10. Furthermore, a portion of the hydraulic liquid in a quantity corresponding to the pump rod cross section passes through a damping bore 42, a connecting bore 43, an annular passage 44, and a bore 45, by the valve body 32 being lifted, into the chamber 46 of the hollow piston rod 7v Simultaneously, hydraulic liquid is pressed from a chamber 47 below the damping piston 10 through a pull-direction damping valve 48 (Zugstufendampfungsventil) into the chamber 4. whereby the pull-direction damping is realized.

When the piston rod 7 moves inwardly, the valve body 32 will, by means of the valve seat 33, sealingly engage the surface 40 of the insert member 9, and the hydraulic liquid drawn in during the pulling stage is, by opening the check valve 31, pressed from the chamber 46 through the inner bore 30 of the hollow pump rod 24 and the passages 21 into the high-pressure liquid chamber 192. Simultaneously,hydraulic fluid flows from chamber 41 through a pressure stage damping valve 49 into the chamber 47 thereby realizing the pressure stage damping. in view of this pumping operation, the pressure effective for the supporting force of the spring system is reduced in the working chamber 17 whereby the hollow piston rod 7 moves inwardly until the level of the vehicle has been reached. For safety reasons, the pump-limiting valve 22 is arranged in the supporting body 15. This valve 22 will prevent the pres sure in the high-pressure accumulator from increasing unduly to a nonpermissible extent, especially when'thc spring system is rigidly clamped in, for instance, for testing purposes.

in the normal range (P16. 2) of the spring system, the chamber 46 will be under the pressure of the high-pressure accumulator 19 through the passages 21, the inner bore 30 of the hollow piston, rod 20, the bores 29, annular passage 28, longitudinal groove 35, and openings 50 in the abutments 36. [n this way, the valve seat 33 of the valve body 32 is pressed sealingly against the surface 40 whereby the pump effect is interrupted. Within this normal range, when moving the piston rod 7, hydraulic fluid is, in conformity with the cross section 'of the hollow pump rod 24, movedback and forth between the chamber 46 and the high pressure fluid chamber 192. The

damping is effected in the same manner as described above in connection with Figure 1.

For limiting the pressure stage damping and for purposes of preventing underpressure conditions in chamber 47, a pressure stage limiting valve 51 is provided which opens when a and connecting bores 53. ln order to assure that the vehicle under its respective load will also statically maintain its normal position, the insert member 9 is provided with a seal 54 which prevents the escape of hydraulic fluid from the high-pressure liquid chamber 192 through chamber 46 into chamber 41 and back to the working fluid chamber 172. In upward leveling 7 position (Aufregelstellung)FlG. 3-, the abutment 36 will,

when the hollow piston rod 7 is moved inwardly, engage the pump piston 25, and the valve seat 33 on valve body 32 is lifted off from the surface 40 of the insert member 9 so that hydraulic liquid will from the high-pressure liquid chamber 192 pass through openings 21, inner bore 30, bores 29, annular passage 28, longitudinal groove 35, through throttling bore 34, into the chamber 46, and from there will pass through bore 45, annular passage 44, connecting bore 43, and damping bore 42, into the chamber 41 and from here through openings 14, annular chamber 16, and openings 13 into the working fluid chamber 172. in this way the pressure in the working chamber 17 increases, and the piston rod 7 moves outwardly until the surface 40 of the insert member 9 again seats onto the valve seat 33 whereby the level of the vehicle has been reached again. When the vehicle swings through, by closing the check valve 31, the now covered bores 50in the abutment 36 prevent hydraulic liquid from passing from chamber 41 through chamber 46 into the high-pressure liquid chamber 192. Also, in this position, the damping is obtained which has been described in connection with FIG. 1. I

Figure 4 represents a modification of the spring system according to the invention according to which a high-pressure accumulator 55 is arranged above an upper'suspension 56. The outer diameter of the spring element or spring system is with this design considerably reduced when lack of installation space exists. Advantageously, the upper suspension 56 forms a so-called pin suspension into which is built in a check valve 57. After screwing on the high-pressure accumulator 55 and sealing the same toward the outside by a seal 58, first the check valve 57 and after further tightening a check valve 59 of the high-pressure accumulator 55 is opened, and the connection between the high-pressure liquid pressure 552 and a chamber 60 is freed. A working chamber 61 is in this instance advantageously by means of a pipe 62 of synthetic material having its upper end forming a sealing ring 63 and having its lower end immersed in the slight liquid level of the working chamber 61, subdivided into a working gas chamber 611 and a working fluid chamber 612. This is effected in such a way that when the hollow piston rod 7 is in motion, only hydraulic fluid can pass from the working fluid chamber 612 through an annular chamber 64 and via openings 14 into the chamber 41.

A hydropneumatic spring element or spring system without damping is illustrated in FIG. 5. Within the pumping range, when the hollow piston rod 65 moves'inwardly, a check valve 66 is lifted off by a piston 67 and fills a'chamber 68 below the piston 67 with hydraulic fluid from a chamber 69 above the piston 67, which chamber 69 communicates through openings 17, annular chamber 71 and openings 72 with the working fluid chamber 732. a

When the piston rod 65 moves outwardly, by closing the check valve 66 and lifting a valve seat 86 of a valve body 74 off a surface 75 of the piston 67, the previously drawn-in liquid is from the chamber 68 pressed through a channel 76 into a chamber 77 and from there through

bores

78, 79, and 80 ofa connecting rod 81 into a high-pressure liquid chamber 822. The piston rod 65 moves inwardly until a piston ring 83 passes over a groove 84 in a cylinder 85 whereby the pump effect is ended. In this normal position, the pressure of a highpressure accumulator 82 acts through

bores

80, 79, 78 onto the valve seat 86 of the valve body 74 and presses the same together by means of the preload of a pull spring 87 in a sealing manner against the surface 75 of piston 77. When the vehicle is loaded and thepiston 65 moves inwardly, an abutment 88 of the valve body 74' engages the bores 79 of a closure member 89 whereby the valve seat 86 with the valve body 74 is lifted off the surface 75 and hydraulic liquid is passed from the high-pressure liquid 822 through a bore 80, and a throttling bore 90 into the chamber 77 and from there passes through passage 76 into the chamber 68 and through groove 84 into the chamber 69. From here the liquid passes through openings 70 into the annular chamber 71 and openings 72 in the working fluid chamber 732 whereby an increase in the working gas chamber 731 will be realized which bririgs about an-outwardly movement of the piston rod 65 until the valve seat 86 again seats on the surface 75 and the vehicle is again on the desired level. In order to be able to keep the vehicle also while his standing still over a longer period of time at the desired level, a seal 91 is provided. h

it is, of course, to be understood that the present invention is, by no means, limited to the specific showing in the drawings, but also comprises modifications within the scope of the appended claims.

What I claim is;

ll Ahydropneumatic spring system having automatic level control both for regulation of loads during standstill and relief thereof controlled during running operation, especially for motor vehicles with two separate preloaded gaseous cushions operable toact upon a hydraulic medium which is controlled according to loadby a purhp and control mechanism, which compr ses: a cylinder, a hollow piston rod rcciprocably arranged in said cylinder, a high pressure fluid storage container, operating chamber means associate with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hollow piston rod, a pump piston carried by a free end of said hollow pump rod, at valve body slidablyguided with respect to said hollow pump rod and having an abuttneht operable in upward leveling position to test against said pump piston, said valve body includihg valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, and throttle means associated with said valve body and operable in response to said valve seat means disengaging said seat surface to estttblishfluid communication between said high-pressure fluid storage container and said operating chamber.

L A hydropneumatic spring system according to claim 1, which inclu des a check valve arranged in said pump piston, and in which in upward leveling position said abutment is operable to cover said check valve so as to rearwardly seal and close thc same,

3. A hydropneumatic spring system having automatic level control for regulation of loads during standstill and relief thereof during running operation, especially for inotorvchicles with two separate preloaded gaseous cushions operable to act upon a hydraulic medium which is controlled accbrding'to load by a pump and control mechanism, which comprises: a cyliilder, a hollow piston rod reciproeably arranged in said cylinder, a high-pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hol low piston rod, a pump piston carried bya free end of said hollow ptlnip rod, a valve body slidably guided with respect to said hollow purnp rod and having an abutment operable in upward leveling position to rest against said ump piston, said valve body including valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, throttle means associated with said valve body and operable in response to said yalve seat means disengaging said seat surface to establish fluid communication between said high-pressure fluid storage container and said operating chamber, said pump piston being provided with radial passage means and with an annular passage communicating with said radial passage means, and said valve body having longitudinal groove means adapted in the normal range of said valve body to communicate with said annular passage for conveying the pressure prevailing in said high-pressure fluid storage container through said radial passage means and said ahnular passage to said valve seat means to press the same against said seat surface of said insert member, and preloaded spring means continuously urging said valve seat means against the seat surface of said insert member.

4, A hydropneumatic spring system according to claim 3, in which in pumping range said valve body with the valve seat operating as the inlet valve arid making possible pump operation with said check valve iri said pump piston.

5. A hydropneumatic spring system according to claim 3, ih which a damping piston is so provided inside said spring system that the suction stepwise damping is buffered between rigid walls and the pressure stepwise damping is effected by means ofthe pressure in the operating chamber. 3

6. A hydropneumatic spring system according to claim 3, which includes guiding means for said piston rod and also includes a pressure stepwise limiting vaIli/e associated with said guiding means for opcratively limiting the pressure stepwise damping.

7. A hydropneumatic spring system according to claim 3, in which an overpressure valve means is provided in a supporting body.

8. A hydropneumatlc spring system according to claim 3, which includes an upper suspension for said spring system and also includes high-pressure storage means arranged above said upper suspension.

9. A hydropneumatic spring system according to claim 8, in which a separating clement formed at its upper end as a sealing ring is immersed in the slight liquid level of the operating chamber.

it). A hydropjncumatilc spring system having automatic level control for regulation of loads during standstill and relief thereof during running operation, especially for motor vchicles with two separate preloaded gaseous cushions operable to act upon a hydraulic medium whichis controlled according to load by a pump and control mechanism, which comprises: a cylinder, a hollow piston rod reciprocably arranged in said cylinder, at high-pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and beihg axially movable in said hollow piston rod, :1 pump piston carried by a free end of said hollow pump rod, a valve body slldably guided with ,respcctto said hollow pump rod and having an abutment operable in upward leveling position to rest against said pump piston, said valve body including valve seat meahs, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, throttle means associated with said valve body and operable in response to said valve seat means discngaging said seat surface to establish fluid communication between said high-pressure fluid storage container and said operating chamber, an upper suspension for said spring system and also high-pressure storage means arranged above said upper suspension, and a check valve being provided in said upper suspension. h i

ll. A hydropneumatic spring system according to clairn,l0 in which a cheelt valve is installed in the high-pressure storage.

12. A hydropheumatic spring system according to claim 10, in which during installation of the high-pressure storage the'rb is an outward sealing with respect thereto, a check valve being provided in said upper suspension of 'the spring system and upon further tightened installation there is opening of tho high-pressure storage by check valve means.

13. A hydropneumatic spring system having automatic level control for regulation of loads during standstill and relief thereof during running operation, especially for motor vehicles with two separatcpreloaded gaseous cushions operable to act upon a hydraulic medium which is controlled according to load by a pump and control mechanism, which comprises: a cylinder, a hollow piston rod reciprobably arranged in said cylinder, a high-pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hollow piston rod, a pump piston carried by a free end of said hollow pump rod, a valve body slidably guided with respect tb said hollow pump rod and having an abutment operable in upward leveling position to test against said pump piston, said valve body including valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat ,mcans, throttle means associated with said valve body and operable in response to said valve seat means disengaging said seat surface to establish fluid communication between said high pressure flu d storage container and said operating chamber, particularly without hydraulic damping there being provided ahollow connectingrod axially movable internally of said hollow piston rod, a closure member pro- '15. A hydropneumatic spring system according to claim 13, in which a piston ring in a groove in normal range controls upwardly in said operating cylinder and thereby stops pump operation, while the pressure of the high-pressure storage through bores is operative upon a valve seat of a valve body and presses the same upon the surface of said piston and avoids a further upward regulation.

16' A hydropneumatic spring system according to claim 15, in which in pumping range the piston is located below the groove in said operating cylinder, said check valve serving as a suction vent and said valve body with the pressure seat serving as a pressure vent whereby the pump operation is attained.

Claims

1. A hydropneumatic spring system having automatic level control both for regulation of loads during standstill and relief thereof controlled during running operation, especially for motor vehicles with two separate preloaded gaseous cushions operable to act upon a hydraulic medium which is controlled according to load by a pump and control mechanism, which comprises: a cylinder, a hollow piston rod reciprocably arranged in said cylinder, a high pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hollow piston rod, a pump piston carried by a free end of said hollow pump rod, a valve body slidably guided with respect to said hollow pump rod and having an abutment operable in upward leveling position to rest against said pump piston, said valve body including valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, and throttle means associated with said valve body and operable in response to said valve seat means disengaging said seat surface to establish fluid communication between said high-pressure fluid storage container and said operating chamber.

2. A hydropneumatic spring system according to claim 1, which includes a check valve arranged in said pump piston, and in which in upward leveling position said abutment is operable to cover said check valve so as to rearwardly seal and close the same.

3. A hydropneumatic spring system having automatic level control for regulation of loads during standstill and relief thereof during running operation, especially for motor vehicles with two separate preloaded gaseous cushions operable to act upon a hydraulic medium which is controlled according to load by a pump and control mechanism, which comprises: a cylinder, a hollow piston rod reciprocably arranged in said cylinder, a high-pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hollow piston rod, a pump piston carried by a free end of said hollow pump rod, a valve body slidably guided with respect to said hollow pump rod and having an abutment operable in upward leveling position to rest against said pump piston, said valve body including valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, throttle means associated with said valve body and operable in response to said valve seat means disengaging said seat surface to establish fluid communication between said high-pressure fluid storage container and said operating chamber, said pump piston being provided with radial passage means and with an annular passage communicating with said radial passage means, and said valve body having longitudinal groove means adapted in the normal range of said valve body to communicate with said annular passage for conveying the pressure prevailing in said high-pressure fluid storage container through said radial passage means and said annular passage to said valve seat means to press the same against said seat surface of said insert member, and preloaded spring means continuously urging said valve seat means against the seat surface of said insert member.

4. A hydropneumatic spring system according to claim 3, in which in pumping range said valve body with the valve seat operating as the inlet valve and making possible pump operation with said check valve in said pump piston.

5. A hydropneumatic spring system according to claim 3, in which a damping piston is so provided inside said spring system that the suction stepwise damping is buffered between rigid walls and the pressure stepwise damping is effected by means of the pressure in the operating chamber.

6. A hydropneumatic spring system according to claim 3, which includes guiding means for said piston rod and also includes a pressure stepwise limiting valve associated with said guiding means for operatively limiting the pressure stepwise damping.

8. A hydropneumatic spring system according to claim 3, which includes an upper suspension for said spring system and also includes high-pressure storage means arranged above said upper suspension.

9. A hydropneumatic spring system according to claim 8, in which a separating element formed at its upper end as a sealing ring is immersed in the slight liquid level of the operating chamber.

10. A hydropneumatic spring system having automatic level control for regulation of loads during standstill and relief thereof during running operation, especially for motor vehicles with two separate preloaded gaseous cushions operable to act upon a hydraulic medium which is controlled according to load by a pump and control mechanism, which comprises: a cylinder, a hollow piston rod reciprocably arranged in said cylinder, a high-pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hollow piston rod, a pump piston carried by a free end of said hollow pump rod, a valve body slidably guided with respect to said hollow pump rod and having an abutment operable in upward leveling position to rest against said pump piston, said valve body including valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, throttle means associated with said valve body and operable in response to said valve seat means disengaging said seat surface to establish fluid communication between said high-pressure fluid storage container and said operating chamber, an upper suspension for said spring system and also high-pressure storage means arranged above said upper suspension, and a check valve being provided in said upper suspension.

11. A hydropneumatic spring system according to claim 10, in which a check valve is installed in the high-pressure storage.

12. A hydropneumatic spring system according to claim 10, in which during installation of the high-pressure storage there is an outward sealing with respect thereto, a check valve being provided in said upper suspension of the spring system and upon further tightened installation there is opening of the high-pressure storage by check valve means.

13. A hydropneumatic spring system having automatic level control for regulation of loads during standstill and relief thereof during running operation, especially for motor vehicles with two separate preloaded gaseous cushions operable to act upon a hydraulic medium which is controlled according to load by a pump and control mechanism, which comprises: a cylinder, a hollow piston rod reciprocably arranged in said cylinder, a high-pressure fluid storage container, operating chamber means associated with said cylinder, a hollow pump rod having an axial bore and being axially movable in said hollow piston rod, a pump piston carried by a free end of said hollow pump rod, a valve body slidably guided with respect to said hollow pump rod and having an abutment operable in upward leveling position to rest against said pump piston, said valve body including valve seat means, an insert member having a seat surface adapted to be engaged and disengaged by said valve seat means, throttle means associated with said valve body and operable in response to said valve seat means disengaging said seat surface to establish fluid communication between said high pressure fluid storage container and said operating chamber, particularly without hydraulic damping there being provided a hollow connecting rod axially movable internally of said hollow piston rod, a closure member provided in the unpreloaded end of said connecting rod, a valve body portion likewise axially movable to slide upon said closure member and engageable in regulating range to abut upon said closure member, said valve body portion thereby lifting from a valve seat of a surface of a piston and making possible passage of hydraulic medium from the high pressure storage into an operating chamber through a throttle bore in said closure member.

14. A hydropneumatic spring system according to claim 13, in which in the regulation position said abutment uncovers sealing of said bores.

15. A hydropneumatic spring system according to claim 13, in which a piston ring in a groove in normal range controls upwardly in said operating cylinder and thereby stops pump operation, while the pressure of the high-pressure storage through bores is operative upon a valve seat of a valve body and presses the same upon the surface of said piston and avoids a further upward regulation.

16. A hydropneumatic spring system according to claim 15, in which in pumping range the piston is located below the groove in said operating cylinder, said check valve serving as a suction vent and said valve body with the pressure seat serving as a pressure vent whereby the pump operation is attained.