POWER BRAKE PRESSURE GENERATOR FOR A HYDRAULIC VEHICLE BRAKING SYSTEM

A pivot bearing of a ball screw of a power brake pressure generator for a hydraulic vehicle braking system is fastened at a hydraulic block with the aid of a sleeve that has an internal circumferential edge, which engages from above with the pivot bearing on a front face facing away from the hydraulic block. The sleeve has a flange that is caulked in an annular step in the hydraulic block.

FIELD

The present invention relates to a hydraulic block including a power brake pressure generator for a hydraulic vehicle braking system.

SUMMARY

The hydraulic block according to the present invention includes a power brake pressure generator. In accordance with an example embodiment of the present invention, the hydraulic block includes a cylinder hole, which is open on one side of the hydraulic block and in which a piston is situated axially shiftable. By shifting the piston in the cylinder hole, it is possible to push away brake fluid from the cylinder hole and to generate a hydraulic brake pressure. By moving the piston in the cylinder hole back and forth, the brake pressure may be raised and lowered, i.e., it is possible to regulate, which is also understood to mean to control, the brake pressure by moving the piston in the cylinder hole back and forth.

For the purpose of shifting the piston in the cylinder hole, the power brake pressure generator includes a threaded drive that converts a rotary driving motion into a shift and shifts the piston in the cylinder hole in a rotary drive. The threaded drive, technically speaking a rotatably drivable driving part of the threaded drive, is pivotable at the hydraulic block via a pivot bearing. The driving part is, for example, a nut or a spindle that shifts the spindle or nut and with it the piston in a rotary drive.

The cylinder hole in the hydraulic block, the piston that is shiftable in the cylinder hole, the threaded drive including the pivot bearing, and potentially a drive motor for a rotary drive of the threaded drive form the power brake pressure generator.

In the case of a return stroke of the piston, during which the piston increases a volume enclosed by it in the cylinder hole and aspirates brake fluid, a negative pressure may form in the cylinder hole that results in a force on the piston that is directed into the cylinder hole. To brace against such a force directed into the cylinder hole, the present invention provides an annular step in the hydraulic block at an orifice at an open side of the cylinder hole, at whose base the pivot bearing of the threaded drive is axially supported. It is possible to support the pivot bearing directly at the base of the annular step at the orifice of the cylinder hole or indirectly via a tubular pivot bearing holder, for example. A caulking or, generally speaking, a plastic deformation of the material of the hydraulic block that surrounds the orifice of the cylinder hole holds the pivot bearing at the hydraulic block. Here, it also applies that the plastically deformed material of the hydraulic block holds the pivot bearing directly or indirectly, for example via the pivot bearing holder, at the hydraulic block.

The plastically deformed material of the hydraulic block preferably holds the pivot bearing in a form-locked manner. For this purpose, the pivot bearing or the pivot bearing holder, at which the pivot bearing is fastened, has an undercut that engages from above or behind with the plastically deformed material of the hydraulic block and thus holds the pivot bearing at the hydraulic block. The undercut is a surface at the pivot bearing or at the pivot bearing holder facing away from the hydraulic block.

Refinements and advantageous embodiments of the present invention are disclosed herein.

All features provided in the description and the figures may be implemented individually on their own or in general in any arbitrary combination in the specific embodiments of the present invention. Embodiments of the present invention that do not include all, but only one or several feature(s) of a specific embodiment of the present invention are generally possible.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Hydraulic block1according to the present invention illustrated inFIG.1includes a power brake pressure generator2for generating a brake pressure and for actuating hydraulic wheel brakes of a hydraulic vehicle braking system using external power. In the illustrated and described specific embodiment of the present invention, hydraulic block1is a cuboid-shaped, flat metal block made of an aluminum alloy, for example, at which wheel brakes (not illustrated) are or may be connected via brake lines.

Hydraulic block1has a cylinder hole3that is open on one side of hydraulic block1, on a large side of cuboid-shaped hydraulic block1in the exemplary embodiment. On an opposite side, cylinder hole3is closed. In the exemplary embodiment, hydraulic block1has a cup-shaped molding4that elongates cylinder hole3. A cover (not illustrated) is, for example, also possible.

A piston5is guided axially shiftable in cylinder hole3. In the exemplary embodiment, piston5is directly guided in cylinder hole3in hydraulic block1. Unlike in the illustration, piston5may also be guided in a cylinder liner, for example, which is situated in cylinder hole3(not illustrated).

By shifting piston5in cylinder hole3in the direction of the closed end, brake fluid may be pushed away from cylinder hole3for the purpose of generating brake pressure and of actuating the wheel brakes (not illustrated) that are or may be connected at hydraulic block1. By moving piston5in cylinder hole3back and forth, the brake pressure may be raised and lowered, and the brake pressure may be controlled or regulated in this manner.

For shifting piston5in cylinder hole3, power brake pressure generator2includes a ball screw6including a spindle7, a tubular nut8, which concentrically encloses spindle7, and balls9, which move in helical grooves outside of spindle7and inside of nut8. In a rotary drive of nut8, which forms in the present case a rotatably drivable drive element10of ball screw6, spindle7shifts axially. In general, ball screw6may also be understood as a threaded drive or as a worm gear.

In the exemplary embodiment, piston5is designed as a tubular hollow piston, whose end facing the closed end of cylinder hole3is closed. Ball screw6is coaxially situated in piston5designed as a hollow piston, spindle7and nut8protruding from an open end of piston5from hydraulic block1. To form a connection to piston5, spindle7has a coaxial pin11that is pressed into a cylindrical indentation in the closed end of piston5.

Nut8, which forms drive element10of ball screw6, is rotatably mounted at hydraulic block1outside of hydraulic block1via a pivot bearing12, a ball bearing in the exemplary embodiment. An outer ring13of pivot bearing12is fastened at hydraulic block1with the aid of an annular or tubular pivot bearing holder14. Pivot bearing holder14coaxially encloses nut8and is coaxial to pivot bearing12. For the purpose of fastening pivot bearing12at pivot bearing holder14, outer ring13of pivot bearing12is pressed onto an annular step of pivot bearing holder14and may be additionally connected to pivot bearing holder14by welding, for example friction welding or spot-welding, or in any other manner.

Pivot bearing holder14protrudes into an annular step15in hydraulic block1at an orifice of cylinder hole3on its open side and is axially supported at a base of annular step15. Pivot bearing12or outer ring13of pivot bearing12is axially supported at hydraulic block1via pivot bearing holder14. Embodiments without pivot bearing holder14are also possible, in which pivot bearing12or its outer ring13is supported (not illustrated) directly at the base of annular step15at the orifice of cylinder hole3in hydraulic block1.

At an outer circumference, pivot bearing holder14has a parallel knurl, i.e., a multi-tooth profile16, which is pressed into an inner circumference of annular step15for fastening same at hydraulic block1. Pivot bearing12is fastened at hydraulic block1via pivot bearing holder14. In the case of a return stroke of piston5, during which piston5may increase a volume enclosed in cylinder hole3, piston5may generate a negative pressure in cylinder hole3that effectuates an axial force on piston5in the direction of the closed end of cylinder hole3. Pivot bearing12is supported against this axial force directed in the direction of the closed end of cylinder hole3via pivot bearing holder14at the base of annular step15, which surrounds the orifice of cylinder hole3in hydraulic block1. The axial force is transferred from piston5via spindle7and nut8of ball screw6to pivot bearing12.

In addition to or alternatively to multi-tooth profile16, pivot bearing holder14includes an annular step at its outer circumference, whose front face is facing an outer side of hydraulic block1and which forms an undercut17. At annular step15at the orifice of cylinder hole3, hydraulic block1is circumferentially caulked, i.e., the material of hydraulic block1surrounding the orifice of cylinder hole3is plastically deformed in such a way that it engages from above with the front face of the annular step, which forms undercut17, at the outside of pivot bearing holder14, by which pivot bearing holder14and, via pivot bearing holder14, pivot bearing12is fastened at hydraulic block1in a form-locked manner.

Instead of indirect fastening via pivot bearing holder14, pivot bearing12or its outer ring13may also be fastened directly at hydraulic block1. Moreover, instead of pivot bearing holder14, for example, pivot bearing12or its outer ring13may have (not illustrated) the parallel knurl that forms multi-tooth profile16and is pressed into annular step15at the orifice of cylinder hole3, and/or, at its outer circumference, the annular step, to whose shape the material of hydraulic block1surrounding annular step15is plastically deformed.

For the purpose of fastening pivot bearing12at hydraulic block1, a tubular sleeve is provided inFIG.2as pivot bearing fastener18that coaxially encloses pivot bearing holder14and pivot bearing12. At an end facing away from hydraulic block1, pivot bearing fastener18has a circumferential inward edge19that engages from above or behind a front face of pivot bearing12or its outer ring13facing away from hydraulic block1. In this way, pivot bearing12is axially held in pivot bearing fastener18in a form-locked manner.

At an opposite end in annular step15, which surrounds the orifice of cylinder hole3in hydraulic block1, pivot bearing fastener18has an outside flange20that is engaged from above by circumferentially caulked, i.e., plastically deformed, material of hydraulic block1surrounding annular step15at the orifice of cylinder hole3, by which pivot bearing fastener18and, via pivot bearing fastener18, pivot bearing12is fastened at hydraulic block1. One side of flange20facing away from the base of annular step15forms an undercut21that engages from above or behind with the plastically deformed material of hydraulic block1.

Similar toFIG.1, inFIG.2pivot bearing holder14may also have a parallel knurl as a multi-tooth profile16that is pressed into the circumference of annular step15at the orifice of cylinder hole3in hydraulic block1.

For the rotary drive of nut8forming drive element10of ball screw6, power brake pressure generator2includes an electric motor22and a planetary gear set23, which is situated between electric motor22and ball screw6. Planetary gear set23and electric motor22are coaxially situated with regard to ball screw6and cylinder hole3at hydraulic block1.

At the same time, nut8of ball screw6forms a planet carrier24of planetary gear set23, on which planet wheels26of planetary gear set23are rotatably mounted on cylinder pins25. Sun wheel27of planetary gear set23is rotatably fixedly situated on a motor shaft28of electric motor22. An annulus gear29of planetary gear set23is rotatably fixedly situated in a cup-shaped holder30that engages from above with outer ring13of pivot bearing12and is, for example, fastened by spot-welding at outer ring13and/or pivot bearing holder14.

Electric motor22is fastened outside on the side of hydraulic block1, at which cylinder hole3is open. Planetary gear set23and spindle7and nut8of ball screw6protruding from hydraulic block1, are located in a motor housing31of electric motor22.

Electric motor22, planetary gear set23, ball screw6including pivot bearing12, and cylinder hole3including piston5, which is axially shiftable in same, form power brake pressure generator2, electric motor22, planetary gear set23, and ball screw6including pivot bearing12forming an external power drive of power brake pressure generator2.

Hydraulic block1includes, in addition to cylinder hole3, a main brake cylinder bore32, in which a main brake cylinder piston (not illustrated) may be situated that is mechanically shiftable in main brake cylinder bore24via a piston rod using a foot brake pedal or a hand brake lever. Via the foot brake pedal or the hand brake lever, a muscular power actuation of the vehicle braking system or of the wheel brakes, which are or may be connected to hydraulic block1, is possible with the aid of the main brake cylinder piston. Moreover, main brake cylinder bore32together with the main brake cylinder shiftable therein and the foot brake pedal or the hand brake lever is used as a setpoint device for a brake pressure that is generated by power brake pressure generator2.

Solenoid valves33are situated at or in hydraulic block1for the purpose of a brake pressure control and/or a slip control. Such slip controls are, for example, an anti-lock system, a traction control system and/or an electronic stability control system or electronic stability programs, for which the abbreviations ABS, TCS and/or ESC or ESP are commonly used. Such slip control systems are conventional and will not be explained here.