ELECTROMECHANICAL BRAKE DEVICE

Abstract

An electromechanical brake device has a brake caliper and a pressure piston mounted in the brake caliper such that it can move in a clamping direction, wherein the brake device has an electromechanical clamping device, wherein the clamping device is supported, on one side, on the pressure piston and is designed to apply to the pressure piston a force acting in the clamping direction. It is provided that the brake device has at least one hydraulically sealed, fluid-filled cavity, wherein the clamping device is supported, on the other side, indirectly on the brake caliper via the fluid-filled cavity, and wherein a pressure sensor is hydraulically connected to the fluid-filled cavity and is designed to calculate the fluid pressure inside the fluid-filled cavity.

Claims

1. An electromechanical brake device with a brake caliper comprising: a pressure piston mounted in the brake caliper such that it can move in a clamping direction; an electromechanical clamping device for the brake device, wherein the clamping device is supported, on one side, on the pressure piston and is designed to apply to the pressure piston a force acting in the clamping direction; at least one hydraulically sealed, fluid-filled cavity of the brake device, wherein the clamping device is supported, on another side, indirectly on the brake caliper via the fluid-filled cavity; and a pressure sensor hydraulically connected to the fluid-filled cavity and designed to calculate the fluid pressure inside the fluid-filled cavity.

2. The electromechanical brake device as claimed in claim 1, wherein the clamping device has an electromotively driven threaded spindle and a spindle nut, wherein the spindle nut is supported on the pressure piston in the clamping direction and wherein the threaded spindle is supported on the brake caliper counter to the clamping direction via the fluid-filled cavity.

3. The electromechanical brake device as claimed in claim 2, wherein the spindle nut is arranged at least partially in a recess inside the pressure piston.

4. The electromechanical brake device as claimed in claim 2, wherein the threaded spindle has a first longitudinal section with a first diameter and a second longitudinal section adjoining the first longitudinal section, wherein an external thread with a diameter greater than the first diameter is formed in the second longitudinal section.

5. The electromechanical brake device as claimed in claim 4, wherein a support ring is arranged on the first longitudinal section of the threaded spindle, wherein the internal diameter of the support ring is smaller than the external diameter of the second longitudinal section of the threaded spindle such that the threaded spindle is supported indirectly on the brake caliper via the support ring counter to the clamping direction via the fluid-filled cavity.

6. The electromechanical brake device as claimed in claim 1, wherein the fluid-filled cavity is formed between a first and a second pressure sleeve, wherein the first pressure sleeved is supported on the brake caliper counter to the clamping direction, while the second pressure sleeve is supported on the clamping device in the clamping direction.

7. The electromechanical brake device as claimed in claim 6, wherein the first pressure sleeve is fastened on the brake caliper.

8. The electromechanical brake device as claimed in claim 6, wherein the first pressure sleeve and the second pressure sleeve each have an opening, wherein the clamping device extends through the opening.

9. The electromechanical brake device as claimed in claim 6, wherein the second pressure sleeve is mounted in the first pressure sleeve such that it is displaceable in the clamping direction.

10. The electromechanical brake device as claimed in claim 9, wherein the second pressure sleeve is mounted on plain bearings on the first pressure sleeve on at least two bearing faces, wherein sealing elements which seal the cavity formed between the pressure sleeves fluidtightly are arranged in the region of the bearing faces on at least one of the first pressure sleeve and the second pressure sleeve.

11. The electromechanical brake device, as claimed in claim 6, wherein the first pressure sleeve and the second pressure sleeve each have a pot-shaped design, wherein at least part of the clamping device extends inside the pot shape.

12. The electromechanical brake device as claimed in claim 11, wherein the pressure sensor is arranged in a side wall of the pot shape of the first pressure sleeve.

13. The electromechanical brake device as claimed in claim 6, wherein the first pressure sleeve and the second pressure sleeve each have a plate-shaped design, wherein the pressure sleeves are connected to each other via membranes at their radial outer rims and at the rims of their respective openings such that the cavity formed between the pressure sleeves is sealed fluidtightly by the membranes.

14. The electromechanical brake device as claimed in claim 13, wherein the pressure sensor is arranged in the plate shape of the first pressure sleeve between the membranes.

15. The electromechanical brake device as claimed in claim 6, wherein the pressure sensor is screwed into the first pressure sleeve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0031] FIG. 1 shows a perspective view of an exemplary electromechanical brake device;

[0032] FIG. 2 shows a view in section of a subregion of a first exemplary brake device;

[0033] FIG. 3 shows a detailed view of the pressure sleeves used in FIG. 2;

[0034] FIG. 4 shows a view in section of a subregion of a second exemplary brake device;

[0035] FIG. 5 shows two detailed views of the pressure sleeves used in FIG, 4; and

[0036] FIG. 6 shows detailed views for the arrangement of a pressure sensor in the pressure sleeves of FIGS. 4 and 5.

DETAILED DESCRIPTION

[0037] Features that are similar or identical to each other are denoted below by the same reference numerals.

[0038] FIG. 1 shows a perspective view of an exemplary electromechanical brake device 100 which is designed in the embodiment illustrated here as a floating-caliper disk brake. The brake device 100 has an electric motor 102 which is connected via a gearbox 104 to a clamping device 106 which is designed in the embodiment illustrated here as a rotation-translation gearbox in the form of a spindle drive. This is explained below in more detail with reference to FIGS. 2 and 4.

[0039] The arrangement consisting of the electric motor 102, gearbox 104, and clamping device 106 is here arranged on a brake caliper 108 which can be fastened via a floating mounting in a brake caliper holder 168 with corresponding fastening points 110 to the wheel suspension of a vehicle. A pressure piston 112 is arranged in the brake caliper 108 such that the pressure piston 112 can be moved in a clamping direction 114 by a corresponding actuation of the electric motor 102 and a resulting activation of the clamping device 106.

[0040] A first friction lining 116, which is moved toward a second friction lining 118 when the pressure piston 112 moves in the clamping direction 114, is in turn arranged on the pressure piston 112. If the brake device 100 is fitted on a vehicle, a brake disk rigidly connected to the vehicle wheel is moreover arranged between the friction linings 116 and 118 such that the first friction lining 116 comes into contact with the brake disk in the case of sufficient displacement of the first friction lining 116 in the clamping direction. If the clamping device 106 is thus activated further, the second friction lining 118 is moved counter to the clamping direction 114, i.e. toward a brake disk arranged between the friction linings 116 and 118, until the two friction linings 116 and 118 bear against the brake disk.

[0041] Beyond this point, when the clamping device 106 is activated further, the friction linings 116 and 118 are pressed against the brake disk such that a deceleration torque which slows down the vehicle is caused on the vehicle wheel. In order to control such an electromechanical brake device 100 to implement a defined braking requirement, it is necessary here to calculate precisely with what force the friction linings 116 and 118 are pressed against the brake disk.

[0042] According to the invention, to achieve this it is provided that the brake device 100 has at least one hydraulically sealed, fluid-filled cavity, wherein the clamping device 106 is, in addition to support on the pressure piston 112, supported on the other side indirectly on the brake caliper 108 via the fluid-filled cavity. A pressure sensor is thus hydraulically connected to the fluid-filled cavity and is designed to calculate the fluid pressure inside the fluid-filled cavity. Two embodiments of this approach are explained in detail below by way of example with reference to FIGS. 2 and 5.

[0043] FIG. 2 here shows a view in section of a subregion of a first exemplary brake device 100. For reasons of clarity, only those elements of the brake device 100 which are relevant for the embodiment are illustrated here.

[0044] As already explained above, the brake device 100 has a clamping device 106 which is designed to apply a force to the pressure piston 112 in a clamping direction 114. To do this, the clamping device 106 has a spindle drive which has a threaded spindle 116 and a spindle nut 166 arranged on the threaded spindle 116. The threaded spindle 116 is here, as explained above, connected via a gearbox 104 which is not illustrated to the electric motor 102 which is also not illustrated such that the threaded spindle 116 can be set in rotation about its longitudinal axis 120 by corresponding actuation of the electric motor 102. The spindle nut 166 is here partly arranged inside the pressure piston 112 and is supported on the pressure piston 112 in the clamping direction. The spindle nut 166 is moreover secured against twisting about the longitudinal axis of the threaded spindle 116 such that rotation of the threaded spindle 116 causes displacement of the spindle nut 166 and therefore the pressure piston 112 in the clamping direction 114. The spindle drive may be designed as a low-friction ball screw.

[0045] In addition to support of the spindle nut 166 and therefore the clamping device 106 on the pressure piston 112 in the clamping direction 114, the clamping device 106 is supported on a fluid-filled cavity 122 counter to the clamping direction. The fluid-filled cavity 122 is here formed between two pot-shaped pressure sleeves 124 and 126 in the embodiment illustrated. A first one of the pressure sleeves 124 is here supported on the brake caliper 108 counter to the clamping direction 114. The second pressure sleeve 126 is mounted in the first pressure sleeve 124 such that it can be displaced in the clamping direction 114. For this purpose, the first and the second pressure sleeve 124 and 126 have bearing faces 128 and 130 on which the pressure sleeves 124 and 126 are mounted on plain bearings such that they can be displaced in the clamping direction 114.

[0046] The cavity 122 formed between the pressure sleeves 124 and 126 is here sealed fluidtightly via sealing elements 132 and 134 formed as sealing rings, wherein the sealing elements 132 and 134 are each arranged in corresponding grooves which are formed in the pressure sleeves 124 and 126. The sealing elements 132 and 134 are here arranged in the region of the bearing faces 128 and 130 of the pressure sleeves 124 and 126 and form plain bearings together with the bearing faces 128 and 130.

[0047] The pot-shaped pressure sleeves 124 and 126 have in their geometry in each case a base surface 136 and 138 and a surrounding side wall 140 and 142. In each case one centered opening 144, through which the threaded spindle 116 extends, is here formed in the base surfaces 136 and 138 of the pressure sleeves 124 and 126. The second pressure sleeve 126 here has, in the region of the opening 144, a projection 146 which extends counter to the clamping direction 114, projects into the opening 144 of the first pressure sleeve 124, and on the radial outside of which the bearing face 130 is formed. One of the plain bearings is thus formed with a sealing element 134 arranged in a groove of the first pressure sleeve 124. The second plain bearing is formed in the side walls 140 and 142 on their axial end regions in the clamping direction 114. For this purpose, formed on the inner face of the side wall 140 of the first pressure sleeve 124 is a bearing face on which a sealing element 132 can slide which is arranged in a groove which is formed in the side wall 142 of the second pressure sleeve 126.

[0048] A pressure sensor 148, which is designed to measure the fluid pressure prevailing in the cavity 122, is moreover arranged in the side wall 140 of the first pressure sleeve 124. The cavity 122 may be filled with a hydraulic liquid. The illustration of an individual element as a pressure sensor 148 is to be understood here as non-limiting. Instead, in the arrangement illustrated, a plurality of pressure sensors 148 can also be hydraulically connected to the cavity 122 such that redundancy is created in the calculation of the pressure prevailing in the cavity 122.

[0049] As has already been explained above, the spindle nut 166 is arranged on the threaded spindle 116 such that it can be displaced non-rotationally and axially along the threaded spindle 116 relative to the brake caliper 108 such that, when the threaded spindle 116 rotates, it causes the spindle nut 166 and therefore the pressure piston 112 to be displaced. When the spindle nut 166 is displaced in the clamping direction, it creates a reaction force counter to the clamping direction 114 which acts on the threaded spindle 116. In order to support this force, arranged on the threaded spindle 116 is a support ring 150 which is designed to absorb a force acting counter to the clamping device 114 and is supported on the second pressure sleeve 126. An axial bearing 152 for absorbing the forces which occur is here formed between the support ring 150 and the second pressure sleeve 126.

[0050] In order to transmit the forces acting on the threaded spindle 116 in the axial direction to the support ring 150, the threaded spindle 116 has two longitudinal sections with a different diameter. The diameter of the threaded spindle 116 in a first longitudinal section 154 is thus smaller than in a second longitudinal section 156, wherein the first longitudinal section 154 extends from the rear end, i.e. that facing the gearbox, of the threaded spindle 116. The external thread of the threaded spindle 116 is here formed in the second longitudinal section 156, wherein the core diameter of the thread is greater than the diameter of the threaded spindle 116 in the first longitudinal section 154. The internal diameter of the support ring 150 is here smaller than the core diameter of the second longitudinal section 156 but greater than the diameter of the first longitudinal section 154 such that the support ring 150 is supported in the clamping direction 114 on the transition between the longitudinal sections 154 and 156.

[0051] If in this arrangement a force is caused on the spindle nut 166 and therefore on the pressure piston 112 by a corresponding actuation of the electric motor 102, precisely this force is likewise also transmitted to the second pressure sleeve 126. As a result, the cavity 122 and the fluid situated inside it is pressurized. The pressure which thus occurs is in turn detected by the pressure sensor 148 such that it is possible to calculate from the calculated pressure the clamping force which currently acts on the pressure piston 112 and therefore on a friction lining 116 arranged on the pressure piston 112.

[0052] FIG. 3 shows again the arrangement of the two pressure sleeves 124 and 126 but without the clamping device arranged therein.

[0053] FIG. 4 shows a view in section of a second embodiment of a brake device 100. The brake device 100 illustrated here differs from the brake device 100 described above with reference to FIGS. 2 and 3 essentially in a different embodiment of the pressure sleeves 124 and 126. Thus, in this embodiment, the pressure sleeves 124 and 126 have a plate-shaped design, wherein the first pressure sleeve 124 is in turn supported on the brake caliper. The second pressure sleeve 126 is mounted such that it can be displaced on the first longitudinal section 154 of the threaded spindle 116 in the activating direction 114. Here too, the threaded spindle 116 is in turn supported on the second pressure sleeve 126 via a support ring 150 counter to the clamping direction 114 such that a force acting on the pressure piston 112 is transmitted to the second pressure sleeve 126.

[0054] Also in this embodiment, a force is applied to a fluidtightly sealed cavity 122 formed between the pressure sleeves 124 and 126 such that the force is reflected in a corresponding change in the pressure prevailing in the cavity 122. The cavity 122 is here, unlike in the above described embodiment, bounded by the pressure sleeves 124 and 126 on one side and by membranes 158 and 160 arranged on the rims of the pressure sleeves. This is illustrated in further detail in FIG. 5.

[0055] In this embodiment too, the pressure sleeves 124 and 126 here also each have centered openings 144 through which the threaded spindle 116 extends. The membranes 158 and 160 designed as bellows are here arranged on the radial outer edges of the plate shape of the pressure sleeves and on the rims of the centered opening 144. The membranes 158 and 160 are here moreover preferably designed such that, although they permit movement of the second pressure sleeve 126 toward the first pressure sleeve 124 within narrow limits, when there are significant changes in pressure inside the cavity 122 they do not bulge radially outward or inward such that a force acting on the cavity 122 is reproduced completely as a change in pressure in the cavity 122.

[0056] The pressure sensor 148 for detecting the pressure prevailing in the cavity 122 is here arranged inside the plate surface of the first pressure sleeve 124 between the membranes 158 and 160. The pressure sensor 148 can here be screwed for example into a corresponding recess 162 such that it can be replaced easily, for example when it is defective.

[0057] Lastly, FIG. 6 shows two further perspective illustrations of the arrangement consisting of the first and second pressure sleeve 124 and 126 with a pressure sensor 148 arranged therein. The interface 164 of the pressure sensor 148 via which calculated pressure information can be communicated to a regulator of the brake device 100 is moreover illustrated here in FIG. 6.