Brakes – Vehicle – Railway
Reexamination Certificate
2002-05-09
2003-10-07
Schwartz, Christopher P. (Department: 3683)
Brakes
Vehicle
Railway
C403S031000
Reexamination Certificate
active
06629584
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The subject matter of the present invention relates to a clamping and/or braking device
BACKGROUND OF THE INVENTION
Clamping and/or braking devices in a variety of different embodiments and for the most varied applications are known. Thus, for example, EP-A-0 936 366 describes a braking device for a linear guide system which has a supporting body that can move along a guide rail. The supporting body has brake shoes which act on both longitudinal sides. The supporting body is designed in the form of an H and has a narrow, flexible bridge and two lower legs by means of which said supporting body embraces the guide rails. The brake shoe is located between each lower leg and the guide rail. The supporting body has two upper legs which, together with the bridge, form a holding space in which a force-generating means that acts on the upper legs is provided. This force-generating means may be a toggle mechanism which can be hydraulically or pneumatically actuated or a piezo-actuator. In addition, a wedge valve serving as a force transducer can be provided, which can be hydraulically or pneumatically actuated and is located in a space specifically provided for this purpose, which space is located between the upper legs of the supporting body and tapers off in the longitudinal direction of the braking device. In all cases, the elastic bridge is bent as a result of the force with pressure is exerted on the two upper legs, thus causing the two lower legs with the brake shoes to move inward and to pressurize the guide rail with greater force.
The disadvantage of this known braking device in combination with the use of an electromechanical transducer, for example, a piezo-element, is, in particular, the sensitivity of said transducer to shock or other mechanical strains.
The assembly and production costs required when a toggle mechanism or a wedge valve as well as an electromechanical transducer are used are high.
In addition, especially in the case of clamping devices, sufficiently high clamping forces are necessary, but given the devices known at this time, to achieve these forces, the structural volume required and thus the financial expenditure.are relatively high.
U.S. Pat. No. 5,855,446 describes a hydraulic clamping bushing which is aligned on a shaft to which it can be connected, for example, without rotational play. The bushing has an essentially stable bushing body which is located at a distance from and around a driving shaft. Abutting this bushing body and facing the shaft is a chamber which can be pressurized. A side wall of this chamber, which runs essentially parallel to the shaft, at the same time serves as a braking element which—when the chamber is pressurized, as a result of which the wall is expanded—is pressed against the shaft, thus producing a frictional lockup connection. The &Sgr;-shaped design of the laterally abutting walls of the chamber is intended to prevent a misalignment of the bushing with regard to the shaft when the chamber is pressurized. Upon pressurization, the &Sgr;-shaped lateral walls of the chamber can expand in the radial direction toward the shaft even before the pressure in the chamber, which is gradually increasing, also presses the wall of the chamber which runs parallel to the shaft against said shaft. This makes it possible for the bushing to be aligned at a right angle with respect to the axis of the shaft before the rotationally tight connection is produced.
In this clamping device, the transmission of forces for the production of high contact pressures is not satisfactory. In addition, the shape that the chamber can have and, in particular, its potential positioning relative to the bushing body are limited. A braking action can be obtained only by means of a pressurization with overpressure, and the actual braking element, which must potentially be able to transmit high driving forces, is not tightly connected to the bushing body but instead only by way of the pressure chamber which is relatively unstable in nature.
Based on this prior art, the problem to be solved by the present invention is to make available a clamping and/or braking device which can be manufactured so as to require a low structural volume and by means of which it is possible to achieve high braking and/or clamping forces. In addition, it should be possible to use the clamping and/or braking device according to the present invention in a variety of applications and, in particular, under conditions of extreme shock and/or vibrations.
SUMMARY OF THE INVENTION
The present invention is based on the recognition that upon pressurization of a suitable chamber by means of a vacuum or by means of overpressure, said chamber should undergo a certain deformation. When such a chamber is largely formed by a wall which is at least approximately straight, the overpressure or the vacuum in the chamber will first cause a deformation which is directed in a first direction which runs essentially perpendicular to this wall. To yield to the deformation (expansion or contraction) which is directed in this first direction, in turn, a corresponding contraction or expansion of the chamber in a second direction results, which second direction generally runs perpendicular to the first direction (i.e., essentially parallel to the wall).
This takes advantage of the fact that low forces or deformations directed in the first direction are able to generate high forces which are directed in the second direction. According to the present invention, these forces are transmitted and utilized for braking or clamping or for releasing prestressed clamping and/or braking devices.
Thus, the chamber is bounded at least in a partial region by a minimum of one flexible but tension-proof and/or pressure-resistant wall The boundary of the chamber that lies opposite to the wall can have the same design as the first wall. But it can also be a rigid portion of a body. Preferably, the walls are located at a relatively short distance from each other. The forces resulting from the deformation of the chamber are transmitted at least in part in the direction of or along the wall and, in the region of the connection of the wall with a basic body, these forces are introduced into said basic body. If the point of application of said forces on the basic body is properly chosen and if this basic body is at least in part elastically deformable, these forces can be transmitted via this basic body to other parts of the basic body, for example, into clamping and/or braking regions. By means of these forces, a suitable braking or clamping means in these regions can subsequently be moved into or out of a pressurizing position so as to brake or release a guide element or an element that is to be clamped or braked. According to the present invention, both the applied overpressure and the applied vacuum in the chamber can be used to introduce both tensile and compressive forces into the basic body. It is, of course, also possible for the clamping and/or braking regions, prior to and after the introduction of the forces, to still be engaged with the guide element or with the element that is to be clamped or braked, in which case, however, changes in the pressurizing forces between the clamping and/or braking regions and the other element result.
In one particular embodiment of the present invention, at least partial regions of the wall in which tensile or compressive forces are to be exerted on the basic body are connected to the basic body by means of an articulated joint region which is narrower than the thickness of the wall. This leads to the advantage of a higher efficiency during the conversion of the pressure exerted on the wall into tensile forces or tensile stresses that are transmitted to the basic body.
In another embodiment of the present invention, the chamber can be formed by two walls which are preferably located at a short distance from each other and which are connected to the basic body along their edges, by means of which the forces are to be transmitted to said basic body. As a result,
InnoTech Engineering GmbH
Schwartz Christopher P.
Shaffer & Culbertson L.L.P.
Torres Melanie
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