1. Field of the Invention
The present invention relates to a hydraulic pressure reservoir having at least one pressure chamber that is formed between two opposed, movable boundary surfaces, each of which includes a spring cover, a diaphragm spring, and at least one free-standing boundary surface.
2. Description of the Related Art
A hydraulic pressure reservoir of this general type is known from International Published Application No. WO 2007/000128 A1. That publication discloses a spring-pressurized reservoir in which two diaphragm springs are clamped between two housing covers that are screwed to control plates.
A disadvantage of a hydraulic pressure reservoir in accordance with the existing art is the comparatively complex screwed connection, which in addition must be able to withstand very high tensile forces acting on the screws.
An object of the present invention is therefore to provide a hydraulic pressure reservoir of the above-indicated type that is simpler and less expensive to produce.
The object is achieved by a hydraulic pressure reservoir having at least one pressure chamber that is formed between two opposed, movable boundary surfaces. Each boundary surface includes a spring cover and a diaphragm spring, as well as at least one fixed boundary surface, where the fixed boundary surface over at least part of its periphery is a solid of revolution of a U-shaped cross section as the generating curve, and which fixes the diaphragm springs in the axial direction. The fixed boundary surface is thus cylindrical in shape over part of its axial extent, and includes regions at the end faces of the cylinder with which the outer perimeter of the diaphragm springs in the axial direction is fixed. To that end, it is preferably provided that the fixed boundary surface is a housing ring having a U-shaped cross section. That makes it possible to construct the pressure reservoir without screws that are loaded in the pressure direction of the diaphragm springs, as is required in the known devices.
The fixed boundary surface is constructed approximately like a steel strip that is bent at the top and bottom and is laid around the set of diaphragm springs. Preferably, the design also provides that the housing ring is in two parts, wherein the housing ring preferably includes two half-rings that are furthermore preferably divided by a plane that passes through the axis of rotation of the solid of revolution. The half-rings are preferably identical in construction.
To install the half-rings, they are placed around the pre-assembled spring set of the diaphragm springs that include spring covers, and are joined to each other. The connection is under load only in the circumferential direction of the solid of revolution. Forces that arise in the axial direction are absorbed by the housing ring itself.
The two half-rings are preferably joined together in a positive connection. The positive connection is preferably a dovetail joint. A connection of that type can be produced easily when manufacturing the half-rings, for example by stamping, and in addition is easy to assemble. The dovetail connection can be made by simply bending the half-rings upward slightly and sliding one over the other during assembly, and is self-locking thereafter. The dovetail joint preferably includes a dovetail on one of the half-rings and a correspondingly shaped recess on the other of the half-rings. Alternatively, it is also possible to provide dovetails and recesses one above the other in the axial direction on each end of the half-rings. The dovetail joint preferably includes means that fix the dovetail joint positively in the radial direction.
Once the connection has been made between the two half-rings, the axial compression force exerted by the diaphragm springs ensures that a tensile force arises in the circumferential direction of the half-rings, which fixes and locks the dovetail connection. To that end, lugs or projections or the like can be provided, for example on the dovetails, which prevent the dovetails from being pressed clear through the recesses. In that way the connection of the two half-rings is self-locking.
In another preferred exemplary embodiment of the invention, the housing ring can also be designed in three parts. If it is then divided into three parts in a plane in which the angle of rotation of the housing ring is situated, the housing ring includes three 120° ring segments.
In addition to the above-described joinder of the housing ring parts by means of a dovetail joint, the two-part or multi-part housing ring segments can also abut each other without a positive lock, in which case the connection is supported by means of a band or ring that surrounds the ring segments to secure them radially. Of course, a plurality of circumferential bands or tensioning rings can also be provided.
The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings in which:
Spring cover 6 includes two adjacent annular grooves in its radially outer region, namely an inner annular groove 11 that has an essentially rectangular cross section, and an outer annular groove 12 that has an essentially rectangular cross section in its radially inner area and which changes to a trapezoidal region with a stop 23 radially toward the outside. Inner annular groove 11 receives a cover-mounted pivot ring 13, and outer annular groove 12 receives a cover-mounted sealing ring 14. Diaphragm spring 8 is supported on the housing side on a housing-mounted pivot ring 15, and is sealed from the environment by a housing-mounted sealing ring 16.
If a hydraulic pressure p is built up within pressure chamber 10, spring covers 6 and 7 and the radially inner regions of diaphragm springs 8 and 9 are pressed in the direction of the arrows 17 shown in
The hydraulic pressure reservoir is connected through a valve (not shown) to a hydraulic system (not shown) by the connection fitting 20. A plurality of tongues 21 extend radially inwardly from the ring-shaped housing-mounted support 19. The tongues 21 serve as spacers between the spring covers 6, 7, to prevent the latter from resting directly flat against each other. If spring covers 6, 7 were in flat contact, the surface area pressurized with the pressure p within pressure chamber 10 would not be sufficient to press them apart against the force of the diaphragm springs. One or more tongues 21 serve at the same time to support a sensor system 22. The outer annular groove 12 of spring covers 6, 7 has a circumferential stop 23, which limits the travel of spring covers 6, 7 in the direction of the arrows 17. Starting at a certain distance in the direction of the arrows 17, the stops 23 contact the diaphragm springs 8, 9, so that the pressure force required for further movement of spring covers 6, 7 suddenly increases.
Sensor system 22 is shown in greater detail in
The sensors are mounted in the seal retainer or a tongue 21 of the seal retainer during injection molding of the seal retainer. The conductor paths for the electric wires 28, 29 for the sensors 24, 25 are also molded directly into the plastic of seal retainer 18 during injection molding, and are routed to the connector 30 to make contact with it. The two sensors assure redundancy in case one sensor fails. In addition, that redundancy makes it possible to ensure that neither of the two springs is overloaded in normal operation.
As an alternative to the above-described sensor system, the sensors can also be built into the spring covers, in which case the magnet is positioned in a tongue 21 of seal retainer 18, as shown in
The spring covers 6, 7 are produced as injection-molded plastic parts, as die-cast aluminum parts, or as aluminum forgings. Magnets provided for the Hall sensors are integrated into the spring covers. In the case of plastic parts, the magnets can be included directly in the injection molding; aluminum parts must be installed later, for example by coining the edge of the aluminum material after inserting the magnet into a provided opening. The spring covers carry the pivot rings for the diaphragm springs, they include a seal surface for the seals between spring coves and the diaphragm springs, and they form a mechanical stop for the diaphragm springs. The seals can be included in the injection molding, similar to the case of a seal retainer, if the spring covers are made of plastic. If the diaphragm springs are pressed in, starting from a certain position the stop 23 comes into contact with the diaphragm spring. That results in a point of application located further outside, which brings the spring cover to a stop despite the rising pressure. This brings about an additional safety function against overloading of the diaphragm springs, along with the sensor monitoring and a pressure-limiting valve located beside the reservoir.
Of course, other methods than the sensor system with magnets just described can also be used to detect the distance between the spring covers, and thereby the stored volume. For example, an inductive solution can be chosen. In that case a large coil with a few windings can be integrated, for example, into the middle part, called the seal retainer, which coil is subjected to a modulated electrical signal. The spring covers must now be chosen of a material that damps the frequency in the coil, independent of the distance between spring cover and coil. Aluminum is an example of such a material. Such a sensor principle requires merely one coil with very few windings, and therefore can be manufactured more economically than a Hall sensor solution.
Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. It is therefore intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention.
Number | Date | Country | |
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60922063 | Apr 2007 | US |