US3620542A

US3620542A - Level control assemblage for vehicles

Info

Publication number: US3620542A
Application number: US817045A
Authority: US
Inventors: Reiner Hovorka
Original assignee: Langen and Co
Current assignee: Langen and Co
Priority date: 1968-05-15
Filing date: 1969-04-17
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16
Also published as: FR2008557A1; GB1266960A; DE1755480A1

Abstract

A level control assemblage for vehicles for stabilizing the distance between the vehicle body and one or more wheelsupporting means independently of load variations at the vehicle and maintaining the distance constant at a preselectable value in which setting or regulating cylinders are connected in series with spring components between the vehicle body and the wheelsupporting means. The pressure spaces of the setting cylinders are connected, dependent upon the distance between the vehicle body and the wheel-supporting means, via one or more level control valves to which the distances are, via linkages communicated, either with a pressure source or with a tank conduit, with the length of the linkages being continuously variable by means of piston-cylinder units installed in the linkages.

Description

United States Patent [72] Reiner Hovorka Wuppertal-Barmen, Germany [211 App]. No. 817,045 [22] Filed Apr. 17, 1969 [45] Patented Nov. 16, 1971 [73] Assignee Langen & Company Dusseldorf, Germany [32] Priority May 15, 1968 [33] Germany [31] P17 55 480.2

[54] LEVEL CONTROL ASSEMBLAGE FOR VEHICLES 5 Claims, 4 Drawing Figs.

[52] US. Cl

[51] Int. Cl 860g 17/04 [50] Field of Search 280/6, 124 F, 6.1, 6.11, DIG. 1; 267/65 56] References Cited UNITED STATES PATENTS 2,978,254 4/1961 Bundorf 3,071,394 1/1963 Miller lnventor 3,074,739 1/1963 Alfieri 280/124 3,209,784 10/1965 Schwartz 280/DIG. 1

FOREIGN PATENTS 1,124,833 3/1962 Germany 280/124 Primary Examiner-Kenneth H. Betts Attorney-Holman & Stern ABSTRACT: A level control assemblage for vehicles for stabilizing the distance between the vehicle body and one or more wheel-supporting means independently of load variations at the vehicle and maintaining the distance constant at a preselectable value in which setting or regulating cylinders are connected in series with spring components between the vehicle body and the wheel-supporting means. The pressure spaces of the setting cylinders are connected, dependent upon the distance between the vehicle body and the wheel-supporting means, via one or more level control valves to which the distances are, via linkages communicated, either with a pressure source or with a tank conduit, with the length of the linkages being continuously variable by means of pistoncylinder units installed in the linkages.

LEVEL CONTROL ASSEMBLAGE FOlR VEHICLES BACKGROUND OF THE INVENTION It is known in the art, and attention is invited to German Provisional Pat. No. 1,124,833 to provide such a level control.

device. The prior device employs a single-acting cylinder provided with a return spring which can be loaded with gas or a liquid by means of a rotary slide valve and thus increase the length of linkage. On the other hand, it is possible to lessen the length of the linkage by discharging gas or liquid.

The disadvantage of this particular arrangement resides in the fact that a sensitive setting of a certain level position is possible only by a pulse-type actuation of the rotary slide valve. In addition, a rotary slide valve is not so tight from the structural viewpoint that repeated correction of the height of the vehicle is not required.

According to another proposal disclosed in the above-mentioned Provisional Patent, a double-acting cylinder equipped with a single piston rod is displaced via a transmitter cylinder having equal effective faces. However, such an arrangement is operable only with air since a blocking occurs with a substantially incompressible liquid due to the known differential effect unless storage components are installed. It should be pointed out that even with a hydrostatic linkage operating satisfactorily under traction and compression, certain disadvantages occur and in particular it is difficult to compensate for volume variations caused by leakages or variations in temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a level control assemblage for vehicles which overcomes the above and other disadvantageous features existing in the art and to provide a sensitive, continuous, and maintenance-free length variation of the linkage with the leakage oil and variations in temperature being compensated for automatically and the setting can be effected from any desired location particularly from the drivers compartment.

The present invention solves the problem by providing a piston-cylinder unit which is a single-acting cylinder having a single piston rod and return spring, with the piston being loaded hydraulically counter to the force of the return spring and the pressure in the liquid being maintained substantially constant by means of an adjustable pressure control valve provided with an outflow aperture.

In a particularly efficacious embodiment of the invention, the piston-cylinder units of each vehicle side may be loaded jointly and it is also possible to adjust the height of the front and rear sections of the vehicle separately and for trimming the vehicle in the unloaded state, the initial tension of the return spring and the basic length of the linkage should be variable.

By the utilization of a pressure control valve having an outflow opening, leakage losses as well as volume increases due to temperature rise are compensated for automatically. In as much as the piston-cylinder units operate substantially statically, there is only a minimum consumption of fluid which is covered from the pressure source already present for supplying the setting or regulating cylinders without an impairment of other functions.

Further objects and advantages of the invention will become more readily apparent to those skilled in the art from the following detailed description and annexed drawings in which drawings:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view illustrating the essential components ofthe invention,

FIG. 2 is a view generally similar to FIG. 1 illustrating the manner in which the piston-cylinders of one vehicle side are loaded jointly,

FIG. 3 is a view along the lines of FIG. 1 illustrating the means whereby the heights of the front and rear sections of the vehicle can be set separately, and

FIG. 4 is a fragmentary view, partly in elevation and partly in cross section depicting means whereby the basic length of the linkage means is variable mechanically and means for adjusting the initial tension of the return spring means of each piston-cylinder unit installed in the linkage means.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, it will be noted that a vehicle (not illustrated in detail) is provided with a rear axle 1 on which are suitably supported

rear wheels

2 and 3.

Front wheels

4 and 5 are operably associated with wheel steering and suspension arrangements 6 and 7.

It will be noted that the rear axle 1 braces itself against the vehicle body (not shown), by means of setting or regulating cylinders 8 and 9 respectively and the steering and suspension arrangements 6 and 7 brace themselves against the vehicle body via setting or regulating

cylinders

14 or 15.

The cylinders 8 and 9 are provided with

pressure spaces

10 and 11 which are in communication with hydroreservoirs l2 and 13 respectively, which function as spring members. Similarly,

pressure spaces

16 and 17 of the cylinders 14 and are connected with

hydroreservoirs

18 and 19.

It will be noted that a line 20 interconnects the

pressure spaces

10 and 11 and a level control valve 22 is provided for the axle l. The valve 22 is provided with ports, A, P, and T and the line 20 is connected to the port A of the valve 22 via line 21. The port P communicates with a pressure source and the port T with a tank a Level control valves 22' and 22" are provided for the steering and suspension arrangements 6 and 7 respectively and the valves are provided with ports A, A", P, P, and T and T".

The

pressure spaces

16 and 17 are connected by way of

lines

23 and 24 with the ports A and A" of the

valves

22 and 22". The connections P and P lead to pressure sources and ports T and T to tanks.

More specifically, the ports T, T and T" are connected to

lines

25, 26 and 27 communicating with tanks 25a and 25b. The connections P, P and P" are supplied via a pressure line or conduit 28 from a common source of pressure denoted generally 29. A pressure limiting valve 30 is provided for serving as protection against overloads.

The level control valves, 22, 22 and 22" secured on the vehicle body are actuated by means of linkages denoted generally 31, 31' and 31" respectively which are articulated to the rear axle 1 and the steering arrangements 6 and 7 respectively.

Piston-cylinder units, 32, 32 and 32" are installed in the

linkages

31, 31 and-3l" and these units are provided with

return springs

33, 33' and 33". Pistons 34, 34' and 34" for the

units

32, 32 and 32" are hydraulically loaded counter to the force of the

return springs

33, 33' and 33" by means of a line or conduit 35 which is connected with the pressure line 28 through a pressure control valve 36 equipped with an outflow aperture. The valve 36 is equipped with a high-pressure port Pe, a consumer connection B and a drain port R.

In the embodiment shown in FIG. 2, components which correspond to those illustrated in FIG. I bear the same reference legends and it will be seen that two pressure regulator valves 136" and 136" are provided. The regulator valve 136' via transmission line effects the piston-cylinder units 32' and 132' at the left side of the vehicle while the regulator valve 136" via transmission line I35" effects the piston-cylinder units 32" and 132 at the right side of the vehicle. By virtue of such an arrangement, it is possible to retain a vehicle body in a level position, even on a strongly inclined slope in the mountains.

With reference to FIG. 3,

pressure regulator valves

236 and 236" are included and the valve 236' by way of a transmission line 235 effects the two piston-cylinder units 232' and 232" arranged at the rear axle I. The regulator valve 236" effects the piston-cylinder units 32' and 32" for the

front wheels

4 and 5 via transmission line 235". This arrangement permits the heights of the front and rear sections of the vehicle to be set separately.

The operation of the present invention is as follows:

A certain setting at the pressure control valve 36 means a reduction of the pressure in the pressure line 28 which is dependent upon the setting of the pressure limiting valve 30 or the load applied to the setting cylinders respectively to a lower pressure in the system denoted B, and line 35. This pressure acts upon the

pistons

34, 34 and 34" of the

units

32, 32 and 32" and an equilibrium position establishes itself between the forces of the

return springs

33, 33' and 33" and the hydraulic pressure force on the

pistons

34, 34' and 34". When by adjustment at the pressure control valve 36, the pressure is increased, the

springs

33, 33 and 33" are compressed more and the length of the

units

32, 32' and 32 and as a consequence the length of the

linkage

31, 31 and 31" increases. The result thereof is a greater ground clearance of the vehicle while on the other hand such ground clearance is reduced at lower pressure since then the lengths of the

linkages

31, 31' and 31" are shortened.

By the construction of the pressure control valve with a drain aperture, leakage'losses and other volume variations are compensated for since all volume variations will bring about a tensioning or relaxing of the

return springs

33, 33' and 33" and hence an increase or decrease of the set pressure.

Upon a pressure drop in the system denoted B, and 35, the liquid will automatically flow from port Pe to B until the set pressure is again attained. Upon an increase in pressure, the connection B-R is established automatically and since the height of the vehicle depends solely upon the height of the reduced pressure, it is advisable to provide, following a proper calibration, a graduation on the control valve 36 by which it is possible to directly read the height of the vehicle. Since, due to possible manufacturing tolerances, the length of the

linkages

31, 31' and 31" may differ from their theoretical lengths, an adjustment to be actuated mechanically may be installed. Similarly, it should be possible to set the initial tensions of the

return springs

33, 33' and 33".

More particularly, in FIG. 4, a piston-cylinder unit 32 is shown in detail and it will be noted that a piston 34 connected with a piston rod 39 moves in a cylinder 38 with the piston being stressed by a spring 33 surrounding the rod 39. One end of the spring 33 bears against the piston 34 while the other end bears against a regulatable component, namely a screw cap or plug 37 through which the piston rod 39 extends. Manifestly, this arrangement enables the initial tension of the spring 33 to be set. 1

It will further be seen in H6. 4 that the free end of the piston rod 39-is provided with a thread 40 which engages a threaded hole 41 in the rod of the linkage 31 and a lock nut 42 is adapted to coact with the thread 40. Obviously, this enables an adjustment of the length of the linkage 31 to be effected mechanically.

With these possibilities of adfiistment, it is possible to easily bring the vehicle into the desired starting position for a given or particular load. With the assistance of additional hydraulic shifting means, it is feasible to connect only the pistoncylinder units of one axle or of one vehicle side with the pressure control valve. The vehicle can be tilted or canted and such possibility may be of interest, for example, for agricultural equipment or utility vehicles. Of course, alternatively, two separate pressure control valves equipped with cor! responding shift means may be utilized.

The stroke of the

piston cylinder units

32, 32' and 32" may be so limited that there still remains spring movement for the cylinders 8, 9, l4 and 15 even in the end positions. Moreover, the stroke may be so great that elastic movement is no longer possible due to the fact the setting cylinders run against their abutment.

Under the invention, it is possible to replace the illustrated hydropneumatic elastic suspension by means of an air suspension or other elastic suspension. In order to avoid a lowering of the vehicle when pump 29 is stationary, releasable check valves may be connected following the

level control valves

22, 22' and 22" as is known per se.

What is claimed is: l. A level control assemblage for vehicles for stabilizing the distance between a vehicle body and one or more wheel supporting means independently of load variations at the vehicle and maintaining the same constant at a preselectable value, comprising setting piston-cylinder units connected in series with spring components between the vehicle body and the wheel-supporting means, a pressure line, a tank line, linkage means operably related to each wheel-supporting means, a level control valve incorporated in each linkage means adapted to provide communication between the pressure line or the tank line and the pressure spaces of the piston-cylinder units dependent upon the distance between the vehicle body and the wheel-supporting means, piston-cylinder units installed in said linkage means whereby the length of the linkage means is continuously variable, each piston-cylinder unit including a single-acting cylinder, a piston and return spring means for the piston, said piston being hydraulically loadable counter to the action of the return spring means, and an adjustable pressure control valve having an outflow aperture for maintaining the pressure in the liquid substantially constant.

2. The level control assemblage for vehicles as claimed in claim 1 in which the piston-cylinders of one vehicle side are loaded jointly.

3. The level control assemblage for vehicles as claimed in claim 1 including means whereby the heights of the front and rear sections of the vehicle can be set separately.

4. The level control assemblage for vehicles as claimed in claim 1 including means whereby the basic length of the link- 7 age means is variable mechanically.

5. The level control assemblage for vehicles as claimed in claim 1 including means for adjusting the initial tension of the return spring means of each piston-cylinder unit installed in the linkage means.

Claims

1. A level control assemblage for vehicles for stabilizing the distance between a vehicle body and one or more wheel supporting means independently of load variations at the vehicle and maintaining the same constant at a preselectable value, comprising setting piston-cylinder units connected in series with spring components between the vehicle body and the wheelsupporting means, a pressure line, a tank line, linkage means operably related to each wheel-supporting means, a level control valve incorporated in each linkage means adapted to provide communication between the pressure line or the tank line and the pressure spaces of the piston-cylinder units dependent upon the distance between the vehicle body and the wheel-supporting means, piston-cylinder units installed in said linkage means whereby the length of the linkage means is continuously variable, each piston-cylinder unit including a single-acting cylinder, a piston and return spring means for the piston, said piston being hydraulically loadable counter to the action of the return spring means, and an adjustable pressure control valve having an outflow aperture for maintaining the pressure in the liquid substantially constant.

4. The level control assemblage for vehicles as claimed in claim 1 including means whereby the basic length of the linkage means is variable mechanically.