BRAKE-FORCE SIMULATOR FOR A MOTOR VEHICLE

Abstract

A brake-force simulator for a motor vehicle includes a piston operatively connectible to an operable brake pedal that is guided in an axially displaceable manner in a cylinder; and at least one elastomer spring element situated in the cylinder, which acts with a spring force counter to the movement of the piston in one direction.

Claims

1-13. (canceled)

14. A brake-force simulator for a motor vehicle, the simulator comprising: a cylinder; a piston operatively connected or connectible to an operable brake pedal of the motor vehicle and guided axially displaceably in the cylinder; and an elastomer spring arranged in the cylinder and applying a spring force against movement of the piston in a direction towards the elastomer spring.

15. The brake-force simulator of claim 14, wherein the elastomer spring is made at least essentially from at least one of ethylene propylene diene rubber and polyurethane.

16. The brake-force simulator of claim 14, wherein the elastomer spring is at least essentially cylindrical and is positioned so that the elastomer spring and the cylinder share a same central longitudinal axis.

17. The brake-force simulator of claim 14, wherein a first end of the elastomer spring is a planar surface that abuts against a bottom of the cylinder.

18. The brake-force simulator of claim 17, wherein a second end of the elastomer spring, that is opposite the first end, is also planar and is orthogonal to a longitudinal axis of the elastomer spring.

19. The brake-force simulator of claim 17, wherein a second end of the elastomer spring, that is opposite the first end, is frustoconical.

20. The brake-force simulator of claim 17, wherein a second end of the elastomer spring, that is opposite the first end, is spherical.

21. The brake-force simulator of claim 17, wherein a second end of the elastomer spring, that is opposite the first end, has a depression.

22. The brake-force simulator of claim 21, wherein the depression forms a concavely shaped vault.

23. The brake-force simulator of claim 17, wherein a second end of the elastomer spring, that is opposite the first end, includes a first axial stop face and a second axial stop face arranged for engagement with the piston.

24. The brake-force simulator of claim 23, wherein the first and second axial stop faces are arranged axially apart from each other.

25. The brake-force simulator of claim 23, wherein the piston includes a first axial stop with which the first axial stop face of the elastomer spring is arranged to engage and a second axial stop with which the second axial stop face of the elastomer spring is arranged to engage.

26. The brake-force simulator of claim 25, wherein the first and second axial stops are arranged axially apart from each other.

27. The brake-force simulator of claim 25, wherein the first and second axial stop faces are arranged axially apart from each other, and the first and second axial stops are arranged axially apart from each other.

28. The brake-force simulator of claim 14, wherein the elastomer spring is designed as a sleeve.

29. A motor vehicle braking device comprising: a brake-force simulator that includes: a cylinder; a piston operatively connected or connectible to an operable brake pedal of the motor vehicle and guided axially displaceably in the cylinder; and an elastomer spring arranged in the cylinder and applying a spring force against movement of the piston in a direction towards the elastomer spring; and a brake pedal that operatively connected to the brake-force simulator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 illustrates, in a simplified longitudinal sectional view, a brake-force simulator having an elastomer element, according to an example embodiment of the present invention.

[0020] FIGS. 2A and 2B illustrate the elastomer element according to an example embodiment of the present invention.

[0021] FIGS. 3A and 3B illustrate the elastomer element according to another example embodiment of the present invention.

[0022] FIGS. 4A and 4B includes lateral and perspective views of the elastomer element according to another example embodiment of the present invention.

DETAILED DESCRIPTION

[0023] FIG. 1 shows, in a simplified longitudinal sectional view, a brake-force simulator 1 of a braking device of a motor vehicle that is not shown in more detail here. Brake-force simulator 1 is designed to be inserted into the braking device developed as a hydraulically operating system. For this purpose, brake force simulator 1 has a cylinder 2, in which a piston 3 is situated in an axially displaceable manner. Piston 3 is additionally situated, guided by at least one sealing ring 4, radially on the periphery close on the inner wall of cylinder 2. It is possible to convey hydraulic medium into the cylinder via a pressure connection 5, whereby piston 3 is axially displaced into cylinder 2. Pressure connection 5 is hydraulically coupled for example to a master brake cylinder of the braking device. Alternatively, it is advantageously provided that piston 3, as shown by dashed lines, is mechanically coupled with a brake pedal of the braking device so that piston 3 is shifted in cylinder 2 by mechanical actuation.

[0024] Furthermore, a spring element 6 is situated in cylinder 2, which rests on the one hand on a bottom 7 of cylinder 2 and on the other hand on piston 3 so that it is able to be braced elastically between these two. If the driver of the motor vehicle applies a braking force hydraulically or mechanically onto piston 3, then piston 3 is moved against spring element 6 so that the spring force provided by spring element 6 counteracts the movement of piston 3. Spring element 6 is here developed as an elastomer element 8, which is manufactured in particular from polyurethane or from ethylene propylene diene rubber.

[0025] Elastomer element 8 is designed in the shape of a cylinder and has, when seen in the longitudinal section, a first section I having a frustoconical contour and a second section II having a frustospherical contour. First section I forms a first end 9, which is supported on cylinder 2, on its bottom 7. The second section II protruding from first section I forms a second end 10 that is assigned to piston 3.

[0026] Front side 11 of elastomer element 8 is developed on first end 9 to be planar and orthogonal to the longitudinal axis of the elastomer element 8 so that it rests by the first end 9 in a planar manner on the bottom 7 of cylinder 2. The other front side 12 of elastomer element 8, which is associated with piston 3, is designed to be spherical and thus abuts in the initial position shown in FIG. 1 against piston 3 only with small surface or in a punctiform manner. Front side 12 thus forms a first axial stop face 13, which increases in size as a function of the contact pressure of piston 3 or of the displacement travel of piston 3. Because section II has altogether a smaller diameter than first section I of elastomer element 8, the latter additionally forms a second axial stop face 14, which lies radially outside of first stop face 13.

[0027] Piston 3 has on its side facing elastomer element 8 a stepped depression, which has at the center a first axial stop 16, and radially outside additionally a second axial stop 17, which is associated with second axial stop face 14 in such a way that, when piston 3 is shifted sufficiently far in the direction of elastomer element 8, the second axial stop 17 strikes the second axial stop face 14.

[0028] All in all, this provides a pedal-force simulator 1, which has an advantageous force-travel characteristic curve and moreover is designed to save space and ensures a long service life.

[0029] FIGS. 2-4 show different alternative exemplary embodiments of elastomer element 8, respectively in a lateral view and in a perspective view.

[0030] FIGS. 2A and 2B also show elastomer element 8 according to a first alternative exemplary embodiment, in which elastomer element 8 is designed on the whole as a cylindrical body. This represents a particularly cost-effective example embodiment. Piston 3 is expediently adapted to the shape of elastomer element 8 in such a way that front side 12 of the latter comes to contact piston 3 in a planar manner or already abuts against it in a prestressed manner in the initial position.

[0031] FIGS. 3A and 3B show a second alternative exemplary embodiment, in which first section I is designed cylindrically and second section II of elastomer element 8 is designed frustoconically. Elastomer element 8 thus likewise has a planar end face 12 for abutting against piston 3, but, due to the frustoconical design of section II, has an improved spring force-travel characteristic curve of elastomer element 8, which thus initially uses only a slight spring force in particular when piston 3, starting from its initial position as shown in FIG. 1, travels only a short distance.

[0032] FIGS. 4A and 4B show another exemplary embodiment of elastomer element 8, which according to this exemplary embodiment is designed to be sleeve-shaped having an axially continuous cavity 18. First section I is again designed cylindrically. Second section II has on its front side 12 a depression 19 in the shape of a concave vault. Between section I and front side 12, elastomer element 8 additionally has a tapered diameter or radial tapering 20, as a result of which end 10 facing piston 3 obtains the shape of a plate spring. This results in additional advantageous properties of elastomer element 8 in pedal-force simulator 1, in particular with respect to the spring force-travel characteristic curve. Cavity 18 can be used, for example, to situate and guide an additional helical spring in pedal-force simulator 1, which provides an additional spring force acting on piston 3.