Abstract:
A pedal lever ( 2 ) for actuation with the foot is connected to an actuating element ( 18 ) by a spring element ( 12 ) in such a manner that an actuating force is introduced directly or by a component ( 13 ), but the restoring force introduced into the pedal lever ( 2 ) by a restoring spring element ( 6 ) is transmitted only up to a maximum permitted value. As soon as this value is exceeded, the spring element ( 12 ) absorbs the force exceeding it. As a result, the actuating element ( 18 ) is protected against damage caused by excessive introduction of force during the restoring movement.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a pedal mechanism, in particular for a vehicle, having a pedal lever which is mounted pivotably about an axis, can be deflected by foot force and can be pivoted back into a basic position by a restoring spring element, an actuating element being actuable by the pedal lever. 
     Pedals of the abovementioned type have long been customary in motor vehicles and are therefore generally known. If the driver of a motor vehicle moves back his foot which is actuating the pedal lever, the pedal lever then has to follow this movement. If the driver takes his foot off the pedal lever completely in order, for example, to actuate the accelerator after a braking procedure, the pedal lever then has to move back relatively rapidly into its inoperative position. This restoring movement is usually made possible by means of a restoring spring element. When the actuating force is suddenly taken away by the foot letting go or sliding off from the pedal lever, the spring force of the restoring spring element causes the pedal lever to accelerate relatively powerfully (what could be termed allowing it “to snap”). If this movement is only stopped by the actuating element as soon as it has reached its maximum deflection or has arrived against its stop, it may be that the force applied to the actuating element by the momentum of the pedal lever exceeds the highest permissible force and damage to the actuating element occurs. 
     Overloading of the actuating element can be counteracted by a stop or a stopper which limits the movement of the pedal arm being provided on the pedal mechanism. However, it has proven disadvantageous here that the stop has to be matched exactly to the associated actuating element in order to achieve the desired effect. This requires complicated setting and adjusting activities, which are associated in turn with increased costs. At the same time, the conversion to different vehicle or motorization variants is also difficult. Furthermore, the maximum possible deflection, which is limited by the actuating element, is reduced by the stop, since the theoretically possible maximum deflection has to be reduced by a safety margin which ensures permanently reliable 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of providing a pedal mechanism of the described type, in which damage to the actuating element can largely be ruled out and at the same time a stop or a stopping element for limiting the restoring movement of the actuating element can be dispensed with. 
     According to the invention this problem is solved by the pedal lever being connected to the actuating element by a spring element which is provided in order to limit the force transmitted to the actuating element by the pedal lever during the restoring movement of the pedal lever by decoupling the pedal lever from the actuating element. By this means, when the pedal lever is actuated, the actuating element is actuated as in the case of a conventional pedal lever and the actuating force is transmitted to the actuating element. When the actuating force is suddenly taken away, the pedal lever swings back under the action of the restoring spring force. If, in this case, the highest permissible force for the actuating element is exceeded, the spring element is tensioned. The maximum force acting on the actuating element in the release direction is therefore determined by the configuration of the spring element. Damage to the actuating element, which may be a hydraulic cylinder, for example, is therefore ruled out. A stop can either be omitted completely or serves merely to limit the movement in the restoring direction if the spring element is tensioned and the distance between the pedal lever and the actuating element is therefore enlarged. 
     A particularly advantageous embodiment of the invention is provided if a component is arranged between the actuating element and the spring element, which component is designed such that in the actuating direction, it can move together with the pedal lever, and, in the restoring direction, it can move relative to the pedal lever against the spring force of the spring element. This makes it possible, on the one hand, to decouple the actuating element during the restoring movement from the movement of the pedal lever and, on the other hand, to relieve the load on the spring element in the actuating direction. A defined path of movement in the component is preferably established. Lateral deviation of the actuating element is thus prevented. The actuating element therefore reliably returns into its inoperative position. 
     It is advantageous here if the component bears against the pedal lever when the latter is actuated. As a result, the actuating force is transmitted to the actuating element from the pedal lever by means of the component with the spring element being excluded. By this means, the spring element is not subjected to load when the pedal is actuated and is therefore subject to considerably less wear. Possible compliance of the pedal mechanism in the actuating direction, caused by the spring element being loaded in a direction opposed to the direction of action, can therefore be avoided. 
     A particularly simple embodiment of the invention in terms of structure is one in which the component and the pedal lever are arranged pivotably about a common axis. This enables very compact constructions of the pedal mechanism to be realized. At the same time, the path of movement of the arrangement, in particular of the actuating element, is unchanged as compared to a conventional pedal mechanism. Only very slight changes to existing pedal mechanisms are therefore required, and so this embodiment is also suitable for retrofitting purposes. 
     The present invention is suitable in principle for all intended uses. The pedal mechanism according to the invention is particularly suitable for use in a motor vehicle if the pedal lever is a brake pedal lever and the actuating element is a braking device. While accelerators are increasingly provided with electric actuating elements whose actuating forces can be configured to be considerably lower, brake pedal levers in passenger vehicles and commercial vehicles are generally also used for the (hydro)mechanical transmission of -the actuating force to a braking device or for the (hydro)mechanical activation of a brake servo. The restoring force of the restoring spring element then depends primarily on the configuration of the braking device and brake servo. These are generally produced in large piece numbers, with the result that individual configurations for the intended purpose, in particular with an individually reinforced stop for the pedal mechanism, are generally not possible. 
     A particularly simple embodiment of the invention is provided if the spring element is a tension spring. This can easily be integrated into the connection between the pedal lever and the actuating element and at the same time can also be designed to transmit compressive forces. 
     Another embodiment is provided if the spring element is a compression spring. In the event of the spring element failing, for example should the spring element break, such a spring element makes possible a restoring movement of the actuating element. The actuating element is thus decoupled from excessively high restoring forces, on the one hand, but at the same time has a stop which guides the actuating element into the inoperative position when the compression spring is pressed to the maximum. This may, for example, be effective if the actuating element is jammed in an operating position and no longer returns into the inoperative position. 
     A further advantageous embodiment is provided with a pedal mechanism in which the spring element is a leg spring. This enables a pedal mechanism to be formed which is space-saving and reliable at the same time. To this end, it is possible for the leg spring to be pivotable, for example, about an axis which is shared with the pedal lever and, in a similar manner to a clothes peg, to be supported with one spring clothes arm on the upper side of the pedal arm and, to compress with the other spring arm, the actuating element against the under side of the pedal lever. When the pedal lever is actuated, the actuating force acts directly on the actuating element, and during the restoring movement, when a maximum permissible force is exceeded, the leg spring separates the actuating element from the pedal arm, as a result of which these are pivoted toward each other. 
     Play in the pedal lever can be effectively avoided if, in accordance with another advantageous development of the invention, in the basic position the spring force of the spring element is greater than the spring force of the restoring spring element. This enables the pedal mechanism to be operated particularly regularly and safely. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention permits numerous embodiments. To further clarify its principle two of these are illustrated in the figures of the drawings and are described below with reference to an actuating cycle. In the drawings in a lateral and partially sectional illustration. 
     FIG. 1 shows a pedal mechanism according to the invention having a spring element which is designed as a tension spring, in its inoperative position, 
     FIG. 2 shows the pedal mechanism which is illustrated in FIG. 1, in an actuating position, 
     FIG. 3 shows the pedal mechanism which is illustrated in FIG. 1, in a position after the sudden letting go of the pedal lever, 
     FIG. 4 shows a further pedal mechanism according to the invention with a spring element which is designed as a compression spring, in its inoperative position, 
     FIG. 5 shows the pedal mechanism illustrated in FIG. 4, in an actuating position, and 
     FIG. 6 shows the pedal mechanism illustrated in FIG. 4, in a position after the sudden letting go of the pedal lever. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a pedal mechanism  1  according to the invention in a side view. In this case, a pedal lever  2  is mounted pivotably about an axis  3  which is arranged on a positionally fixed bearing arrangement  4 . The pedal lever  2  has a lever arm  5  having a restoring spring element  6  which is designed as a tension spring, is supported against a positionally fixed abutment, which is designed as a base plate  29  of the pedal mechanism  1 , and in the inoperative position which is illustrated is relaxed. The lever arm  5  is at a small distance from a positionally fixed stop  7 , which is designed, for example, as a rubber buffer. On a lever arm  8  which lies opposite the lever arm  5 , the pedal lever  2  has a section  10  which is designed as a pedal plate  9  and is designed for actuation with the foot. Likewise arranged on the lever arm  8  of the pedal lever  2  is an approximately cup-shaped holder  11  for a spring element  12  which is inserted therein and is designed as a tension spring. The spring element  12  connects the pedal lever  2  to a component  13  which is likewise mounted pivotably about the axis  3 . The lever arm  8  of the pedal lever  2  is inserted into a recess  14  of the component  13  in such a manner that a movement, which is largely independent of the component  13 , about the axis  3  is possible. The component  13  is furthermore connected by means of a pin  15  to a piston rod  16  of an actuating element  18 , which is designed as a braking device  17  and only certain sections of which are illustrated. In the inoperative state which is illustrated, the spring force of the spring element  12  is greater than the spring force of the restoring spring element  6 , with the result that the lever arm  8  of the pedal lever  2  bears against the component  13  which is connected to the piston rod  16 . 
     FIG. 2 shows the pedal mechanism  1  in an actuating position which is loaded by the actuating force F B . Compared to the inoperative position illustrated in FIG. 1, the pedal level  2  is now situated in a position which is deflected counter to the spring force of the restoring spring element  6  by an angle of deflection α. In this case, the actuating force F B  which acts on the pedal plate  9  of the pedal lever  2  is transmitted to the component  13  which is pivoted together with the pedal lever  2  and bears against the latter. The piston rod  16  of the braking device  17 , which piston rod is actuated by means of the pin  15 , is therefore partially inserted into the braking device  17 . No forces act here on the spring element  12 . 
     FIG. 3 shows the pedal mechanism  1  in a position after a sudden falling away of the actuating force (F B ). The component  13  is returned again into its inoperative position which is illustrated in FIG.  1 . In this case, the force applied to the spring element  12  by the restoring spring element  6  in conjunction with the mass moment of inertia of the pedal lever  2  has exceeded a maximum permissible force. The pedal lever  2  is therefore situated in a position which is pivoted with respect to the component  13  against the spring force of the spring element  12 . The restoring force acting on the actuating element  18 , which is designed as a braking device  17 , corresponds in this case to the force transmitted by the spring element  12 . The piston rod  16  is therefore situated in a position drawn out of the braking device  17  to its maximum. Decoupling the pedal lever  2  from the braking device  17  prevents damage to the braking device  17  due to inadmissibly high restoring forces. Because of the relatively great spring force of the spring element  12  in the inoperative position as compared to the spring force of the restoring spring element  6 , the lever arm  8  of the pedal lever  2  is again pulled up to the component  13 , which is connected to the piston rod  16 . 
     FIG. 4 shows an embodiment which is modified as compared to the pedal mechanism illustrated in FIGS. 1 to  3 , in which corresponding components are provided with corresponding reference numbers. In this case, an actuating element  20 , which is designed as a braking device  19 , is passed through a recess  22  in a pedal lever  23  by means of a piston rod  21 . Between an expanded portion  24 , which is arranged at the free end of the piston rod  21 , and the recess  22  a spring element  25 , which is designed as a compression spring, surrounds an end section of the piston rod  21 . The spring element  25  is supported here on an edge  26  of the recess  22 . On that side of the pedal lever  23  which lies opposite the spring element  25  a curved component  27 , which is connected fixedly to the piston rod  21 , bears against the recess  22 . In the rest state which is illustrated, the spring force of the spring element  25  is greater than the spring force of a restoring spring element  6 , which is designed as a tension spring, with the result that the pedal lever  23  is clamped between the curved component  27 , which is connected to the piston rod  21 , and the spring element  25 , which is designed as a compression spring. 
     FIG. 5 shows the pedal lever  23  in an actuating position subjected to the actuating force F B  in a similar way to the illustration in FIG.  2 . Compared to the inoperative position illustrated in FIG. 4, the pedal lever  23  is now situated in a position which is deflected against the spring force of the restoring spring, element  6  by an angle of deflection α. The actuating force F B  acting on a pedal plate  28  of the pedal lever  23  is transmitted here by means of the component  27  directly to the piston rod  21  of the braking device  19 , so that said piston rod is partially inserted into the braking device  19 . The spring element  25  is situated here in an insignificantly lengthened position caused by the slightly changed angular position of the piston rod  21  with respect to the pedal lever  23 . 
     FIG. 6 shows the pedal lever  23  after the sudden removal of the actuating force (F B ), the piston rod  21  being returned into its inoperative position illustrated in FIG. 4 by means of the component  27  which is arranged on it. In this case, the restoring force of the restoring spring element  6  has exceeded the maximum force which can be transmitted to the pedal lever  23  by the spring element  25 . In the process, the piston rod  21  of the braking device  19  is pulled as far as possible out of the braking device  19 , while the pedal lever  23  is swung far back. As a result, the spring element  25 , which is designed as a compression spring, is tensioned between the expanded portion  24  and the edge  26  of the recess  22 . In this case, the component  27  which is arranged on the piston rod  21  does not bear against the recess  22 . Because of the relatively great spring force of the spring element  25 , which is designed as a compression spring, in the inoperative position as compared to the spring force of the restoring spring element  6 , the pedal lever  23  is again brought up to the curved component  27  which is connected to the piston rod  21 .