Brakes – Operators – Electric
Reexamination Certificate
2000-04-21
2001-07-31
Oberleitner, Robert J. (Department: 3613)
Brakes
Operators
Electric
C188S156000
Reexamination Certificate
active
06267208
ABSTRACT:
The invention relates to a pedal path simulator as set forth hereinafter.
Pedal path simulators of this type are used in particular in electromotive brakes, as disclosed, for example, in U.S. Pat. No. 4,658 939. The change in the pedal position is converted into an electrical signal which is supplied to a control unit which in turn triggers the wheel brakes.
The purpose of this type of pedal path simulators is to give the driver a pedal feel which corresponds as much as possible to that in conventional hydraulic brakes with vacuum brake boosters and master cylinders.
For example, DE 43 24 041 A1 has disclosed a set point transmitter for controlling a brake system, having a path simulator which includes a piston in a cylinder. On the one end, the piston is acted on by a spring and on the other end, it is loaded by a pre-stressed gas cushion. In the rest position of the piston, the spring functions as a compression spring. When the set point transmitter is actuated, in the course of the movement of the piston counter to the compression force of the gas cushion, the spring begins to function as a tension spring. The resultants of the spring force and compression force lead to a distinct progressivity of the characteristic curve of the path simulator. The path signal and/or pressure signal is converted by means of a measurement converter into an electrical signal in order to trigger a brake system.
Currently, it is not uncommon for the generation of a characteristic pedal path-pedal force characteristic curve with conventional spring elements to lead to large problems.
The object of the invention, therefore, is to produce a pedal path simulator which is in a position to simulate progressive pedal path-pedal force characteristic curves of the type required in motor vehicles in a manner that is technically simple to achieve.
OBJECTS AND ADVANTAGES OF THE INVENTION
This object is attained according to the invention with a pedal path simulator of the type described at the beginning and has the advantage that the embodiment of the restoring means with at least two magnets, whose mutually repelling poles are oriented toward each other, one of the magnets is connected to the pedal and is guided so that the magnet can move in the direction of the resultant repelling magnetic force, and permits complicated progressive pedal characteristic curves to be simulated in a relatively simple fashion.
In this connection, it is particularly advantageous that the embodiment of the restoring means has two magnets, one magnet is considered to be the armature and the other magnet. This is considered to be the armature counterpart, makes it possible to produce practically any arbitrary characteristic curve.
It is also advantageous that such an embodiment of the pedal path simulator permits a very compact construction. Furthermore, the end wall is not required to protrude into the pedal space of the vehicle.
The magnets can be embodied in an extremely wide variety of forms. One advantageous embodiment provides that the magnets are ferromagnetic permanent magnets.
A particularly advantageous embodiment provides that these permanent magnets are magnetic disks which are respectively disposed in a cup that is adapted to them and is made of a soft magnetic material. Such an embodiment is simple to produce and permits practically any arbitrary form of the cups and therefore any arbitrary form of the armature and armature counterpart.
Preferably the provision is made that a non-magnetic sleeve is disposed between the cup and the magnetic disk.
In order to produce the desired pedal characteristic curve, the provision is advantageously made that the characteristic curve of the repelling magnetic force can be changed as a function of the pedal path by means of a shaping of the magnets. It has turned out that by changing the shape of both magnets, an extremely wide variety of force-path characteristic curves can be produced, for example a magnetic force that increases with increasing path can be produced, however it is also possible to produce a force which, with increasing path, increases, then decreases, and increases again, similar to the characteristic curves that are known in switching magnets.
A particularly advantageous embodiment provides that the cup remote from the pedal has a conical shape, with a cone angle that opens on the end remote from the pedal. This produces a force-path characteristic curve which is very similar to that of a known pedal. By changing the cone angle, the force-path characteristic curve can be changed and fixed.
The magnet that can be moved with the pedal is guided by means of a guide rod which is supported so that magnet can slide.
In particular with a view to an advantageous additional guidance when the two repelling magnetic poles must be moved very close to each other, i.e. when the pedal is depressed forcefully, the provision is made that the cup remote from the pedal encompasses the cup oriented toward the pedal at least partially when the pedal is depressed.
In another embodiment, the magnets are advantageously electromagnets whose field intensities can be influenced by the current intensity.
In order to transmit the pedal position to a control unit or the like, the provision is made that sensors for detecting the pedal position are provided on a housing that contains the magnets.
REFERENCES:
patent: 6105737 (2000-08-01), Weigert et al.
Greigg Ronald E.
Griegg Edwin E.
Kramer Devon
Oberleitner Robert J.
Robert & Bosch GmbH
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