Pressure generator for a hydraulic vehicle braking system
The pressure generator addresses the challenge of compact design and efficient pressure generation in hydraulic braking systems by integrating a piston-cylinder unit, screw drive, and planetary gear unit with positive-locking connections, achieving a compact and efficient pressure generation system.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2014-06-27
- Publication Date
- 2026-06-11
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[0001] The invention relates to a pressure generator for a hydraulic vehicle braking system, comprising the features of the preamble of claim 1. The pressure generator is particularly intended for use in a hydraulic power-assisted braking system and can also be used for slip control in hydraulic power-assisted, auxiliary, and human-powered braking systems. Furthermore, the invention relates to an assembly tool for the pressure generator, comprising the features of the preamble of claim 7, and a method for assembling the pressure generator, comprising the features of the preamble of claim 8. State of the art
[0002] DE 100 14 993 A1 discloses an electromechanical wheel brake device with a screw drive for converting a rotary movement of an electric motor into a translational movement of a brake piston for mechanically pressing a brake pad against a brake disc in a delivery stroke and for releasing the brake pad in a return stroke.
[0003] Japanese patent application JP H04 22767 A discloses a pressure generator, described as a hydraulic plunger pump, with a ball screw drive and a piston-cylinder unit. The ball screw drive has a spindle nut that can be driven by an electric motor, thereby axially displacing a spindle that in turn displaces a piston in a cylinder of the piston-cylinder unit. In one embodiment, the spindle nut is driven directly by a coaxially arranged hollow-shaft electric motor surrounding the ball screw drive, while in another embodiment, an electric motor arranged axially parallel to the screw drive is driven via a spur gear transmission. Disclosure of the invention
[0004] The pressure generator according to the invention, with the features of claim 1, comprises a piston-cylinder unit with a cylinder and a piston displaceable within the cylinder, as well as a screw drive for displacing the piston. The screw drive comprises a rotatable, axially fixed component with a thread and an axially displaceable, rotationally fixed component with a mating thread, the mating thread of which engages directly or indirectly, for example via rolling elements, with the thread of the rotatable component of the screw drive. A rotary drive of the rotatable component of the screw drive displaces the axially displaceable component of the screw drive axially. The axially displaceable component of the screw drive is axially fixed to the piston of the piston-cylinder unit, so that a displacement of the axially displaceable component of the screw drive displaces the piston within the cylinder of the piston-cylinder unit.
[0005] According to the invention, the pressure generator comprises a hollow, for example tubular, force transmitter that transmits an axial force, which causes pressure generation with the piston-cylinder unit, between the piston-cylinder unit and the rotatable component of the screw drive. The force transmitter can transmit the axial force directly or indirectly via one or more further components. In particular, the rotatable component of the screw drive is rotatably axially supported on the force transmitter, and the force transmitter is directly or indirectly connected to the cylinder of the piston-cylinder unit. At least a portion of the screw drive's length is housed within the hollow force transmitter, which enables a compact design of the pressure generator.
[0006] The pressure generator according to the invention comprises a planetary gear unit for a rotary drive of the rotatable component of the screw drive, which is arranged coaxially to the screw drive at one end of the screw drive unit furthest from the piston-cylinder unit. A planet carrier of the planetary gear unit is connected to the rotatable component of the screw drive unit in a rotationally fixed manner by a positive-locking connection, so that a rotary drive of the planet carrier of the planetary gear unit rotates the rotatable component of the screw drive unit. For assembly, the planet carrier is placed axially onto the rotatable component of the screw drive unit; that is, the positive-locking connection is designed such that it engages upon axial movement of the planet carrier with respect to the rotatable component of the screw drive unit, thus connecting the planet carrier to the rotatable component of the screw drive unit in a rotationally fixed manner by positive locking.
[0007] Furthermore, a ring gear of the planetary gear of the pressure generator according to the invention is also rotationally fixed to the power transmitter by a positive locking connection. This positive locking connection is also engaged by an axial movement of the power transmitter relative to the ring gear.
[0008] The dependent claims relate to advantageous embodiments and further developments of the invention specified in claim 1.
[0009] Form-fit connections that can be closed by axial movement and are rotationally fixed include, for example, a tongue and groove connection, a polygonal connection, or a splined connection. An embodiment of the invention according to claim 2 provides a pin connection with an eccentrically arranged, axially parallel pin that engages in a hole. In principle, one such pin is sufficient, which is suitable, for example, for the rotationally fixed form-fit connection of the ring gear of the planetary gear to the hollow power transmission. A further development according to claim 3 provides a pin connection with several pins as a form-fit connection, the pins of which are arranged evenly or unevenly distributed around a circumference.
[0010] A preferred embodiment of the invention, which enables a compact design of the pressure generator, provides an electric hollow-shaft motor for the rotary drive of the planetary gear. The hollow-shaft motor has a cup-shaped rotor that encloses the planetary gear and at least part of the length of the helical gear. An end wall of the rotor, located on the side of the planetary gear, has mounting openings through which the planet gears with the planet carrier and the ring gear of the planetary gear can be held during assembly with the rotatable component of the helical gear and the hollow power transmission within the rotor.
[0011] Claim 7 relates to an assembly tool with holders for the planet gears and the ring gear of the planetary gearbox, wherein the planet gears can also be held via the planet carrier. The assembly tool holds the planet gears and the ring gear in the correct position through the mounting openings in the end wall of the rotor of the hollow shaft motor. Correct position means that the positive locking connections of the ring gear with the power transmission and of the planet carrier with the rotatable component of the screw drive are closed by an axial movement and, in particular, do not collide with each other due to a twisted position. After assembly, the assembly tool or its holders are pulled out axially through the mounting openings in the end wall of the rotor of the hollow shaft motor. Brief description of the drawing
[0012] The invention is explained in more detail below with reference to an embodiment of the invention illustrated in the drawing. The drawing shows: Fig. 1. an axial section of a printing generator according to the invention; and Fig. Two parts of the printing generator and an assembly tool according to the invention during assembly. embodiment of the invention
[0013] The pressure generator 1 shown in the drawing, according to the invention, serves to generate pressure in a hydraulically assisted braking system. It can also be used for a slip control system. The pressure generator 1 comprises a piston-cylinder unit 2 with a piston 3 and a cylinder 4, which is designed as a cylindrical recess in a hydraulic block 5 of the vehicle braking system (not shown). The hydraulic block 5 serves for the mechanical mounting and hydraulic connection of hydraulic components of a slip control system of the vehicle braking system, such as solenoid valves, check valves, hydraulic accumulators, and the piston-cylinder unit 2. Such hydraulic blocks 5 for slip-controlled vehicle braking systems are known and will not be discussed in detail here.In an external power braking system, the piston-cylinder unit 2 serves to build up pressure instead of a foot- or hand-operated master brake cylinder, which serves as a brake force setpoint generator for external power braking and with which a brake pressure for auxiliary braking can be generated in the event of failure of the external power brake.
[0014] The piston 3 of the piston-cylinder unit 2 is designed as a hollow piston and has a spindle 6 arranged coaxially within it and rigidly connected to it. The spindle 6 is thus axially and radially fixed to the piston 3. The spindle 6 is arranged coaxially in a spindle nut 7, which projects into the hollow piston 3. A rotary drive of the rotatable and axially fixed spindle nut 7 axially displaces the spindle 6 and with it the piston 3, so that the piston 3 generates hydraulic pressure in the cylinder 4. Together, the spindle 6 and the spindle nut 7 form a screw drive 8. In the illustrated embodiment of the invention, the screw drive 8 is designed as a ball screw drive with a ball return 36, with balls 9 as rolling elements that roll in helical grooves formed as threads and mating threads on the spindle 6 and in the spindle nut 7.In general, the spindle 6 and the spindle nut 7 can be considered components of the screw drive 8, wherein the spindle nut 7 is a rotatable, axially fixed component of the screw drive 8, having a thread, and the spindle 6 is an axially displaceable, rotationally fixed component of the screw drive 8, having a mating thread. In the embodiment as a ball screw drive, the thread of the spindle nut 7 and the mating thread of the spindle 6 engage indirectly via the balls 9, so that, as already described, a rotary drive of the spindle nut 7 axially displaces the spindle 6 with the piston 3. In embodiments of the invention, a reverse configuration is also conceivable, i.e., a rotatable and axially fixed spindle and a rotationally fixed and axially displaceable spindle nut (not shown), wherein in this case the spindle nut is connected to the piston 3, for example, even integrally, and displaces it when the spindle is rotaryly driven.To prevent rotation, the piston 3 and the spindle 6 have an axial blind hole 34 with a hexagonal cross-section into which a hexagonal rod 35 projects, which is screwed into the hydraulic block 5 at the base of the cylinder 4 in a rotationally fixed manner.
[0015] The spindle nut 7 is rotatably mounted in a tubular collar 14 of a flange part 15 by means of a radial bearing 10 and is axially and rotatably supported by an axial bearing 11, which in this embodiment is designed as a needle bearing, on a flange, here referred to as the abutment 12, which is arranged in a tubular force transmitter 13. In this embodiment, the radial bearing 10 and the axial bearing 11 are arranged at an end of the spindle nut 7 furthest from the piston 3. The force transmitter 13 has a thread 37 by which it is screwed onto a mating thread of the tubular collar 14 of the flange part 15, i.e., it is firmly connected to the collar 14.
[0016] The flange part 15 has a flange 16 which is mounted in a recess of the hydraulic block 5. The flange part 15 is coaxial with the cylinder 4, the piston 3, the spindle 6, and the spindle nut 7. The collar 14 of the flange part 15 guides the piston 3 coaxially to the cylinder 4 and axially displaceably. The collar 14 of the flange part 15 guides the spindle 6 of the screw drive 8 over the piston 3. The spindle 6 is rigidly connected to the piston 3 and thus radially fixed to it, coaxially to the cylinder 4 and the spindle nut 7, and axially displaceable. When the piston 3 is moved into the cylinder 4 to generate pressure, a compressive force acts on the spindle 6 and the spindle nut 7, which is axially supported by the axial bearing 11 at the abutment 12 in the power transmitter 13.The force transmitter 13, which is screwed to the collar 14 of the flange part 15, transmits a tensile force, which arises as a reaction force to the compressive force in the spindle 6 and the spindle nut 7, via the flange part 15, which is attached to the hydraulic block 5, into the hydraulic block 5, which contains the cylinder 4 of the piston-cylinder unit 2. The compressive and tensile forces occurring during pressure generation are thus guided as internal forces in a closed circuit over a short path, so that no external forces act that require support.
[0017] At one end of the spindle nut 7, furthest from the piston 3, a planetary gear set 22 is arranged, comprising a sun gear 20, planet gears 17, a planet carrier 38, and a ring gear 21. The planet gears 17 are rotatably mounted on pins that are inserted into the planet carrier 38 as planet gear shafts 39. In the illustrated embodiment, the planetary gear set 22 has three planet gears 17, although this is not essential for the invention.
[0018] The planet carrier 38 is a circular disk that is rotationally fixed to an end face of the spindle nut 7 furthest from the piston 3 by means of a positive-locking connection 40. In the illustrated embodiment of the invention, the positive-locking connection 40 of the planet carrier 38 to the spindle nut 7 is designed as a pin connection with a number of eccentrically and uniformly or unevenly spaced, axially parallel pins 41 arranged around a circumference. The positive-locking connection 40 can be assembled by an axial movement of the planet carrier 38 relative to the spindle nut 7, which can also be described as closing the positive-locking connection 40. Other axially lockable positive-locking connections 40 are possible for the rotationally fixed connection of the planet carrier 38 to the spindle nut 7, such as a tongue and groove connection, a splined profile, or a polygonal profile. This list is not exhaustive but exemplary.
[0019] The ring gear 21 of the planetary gear 22 is inserted into an end of the tubular power transmitter 13 furthest from the piston 3 and rests axially against an annular step in the power transmitter 13. The ring gear 21 is connected to the power transmitter 13 in a rotationally fixed manner by a positive-locking connection 42. In the illustrated embodiment of the invention, this positive-locking connection 42 is also a pin connection with pins 43 projecting axially parallel to the ring gear 21, which engage in holes in the power transmitter 13. The positive-locking connection 42 of the ring gear 21 with the power transmitter 13 is also closed by an axial movement of the ring gear 21 relative to the power transmitter 13. Other axially lockable positive-locking connections 42 are also possible for the rotationally fixed connection of the ring gear 21 with the power transmitter 13, such as a tongue and groove connection, a splined profile, or a polygonal joint. This list is not exhaustive, but rather exemplary.
[0020] The sun gear 20 is rotationally fixed to a shaft 23, which is rotationally fixedly pressed into a collar 24 in an end wall 25 of a cup-shaped hollow shaft 26 of an electric hollow shaft motor 27. The hollow shaft 26 has poles or permanent magnets 28 on its outside and can also be considered the rotor of the electric hollow shaft motor 27. The hollow shaft 26 concentrically surrounds the planetary gear 22, the helical gear 8, the power transmitter 13, and the collar 14 of the flange part 15. It is rotatably mounted near the flange 16 by a ball bearing as a rotary bearing 29. The flange-adjacent rotary bearing 29 of the hollow shaft 26 is pressed onto a bearing seat 19 on the outside of the flange part 15, close to the flange 16.
[0021] The electric hollow-shaft motor 27 has a cup-shaped motor housing 30 with stepped diameters, the open end of which is attached to the flange 16 of the flange part 15. On one inner side, the housing 30 has electromagnets as stator magnets 31. The motor housing 30 with the stator magnets 31 can also be considered the stator of the electric hollow-shaft motor 27. At a closed end facing away from the flange 16, a hollow cylindrical bearing seat 32 is formed on the motor housing 30, in which a ball bearing is arranged as a rotary bearing 33. The shaft 23 is rotatably mounted to the rotary bearing 33, and the shaft 23 is rotationally fixed to the sun gear 20 of the planetary gear 22 and, by being pressed into the collar 24 of the hollow shaft 26, is rotationally fixed to the hollow shaft 26. The rotary bearing 23 thus supports both the hollow shaft 26 of the electric hollow shaft motor 27 at the end furthest from the flange 16 and at the same time allows the sun gear 20 of the planetary gear 22 to rotate.In a rotary drive of the hollow shaft 26 of the electric hollow shaft motor 27, the sun gear 20 of the planetary gear 22, which is fixed to rotation with the hollow shaft 26, is driven to rotate and drives the planet gears 17 to a rotary motion, which causes a rotary drive of the planet carrier 38 and the spindle nut 7.
[0022] To assemble the pressure generator 1 or to install the planetary gear 22 and the spindle nut 7 of the screw drive 8 into the hollow shaft 26 of the hollow shaft motor 27, the shaft 23, which secures the sun gear 20 in rotation, is pressed from the inside into the collar 24 of the end wall 25 of the hollow shaft 26, so that the sun gear 20 is arranged in a rotationally fixed and coaxial manner with the hollow shaft 26 on an inner side of its end wall 25. The rotary bearing 33 can be pressed onto a protruding end of the shaft 23 from the outside, either immediately or later. From the outside, an assembly tool 44 is placed onto the end wall 25 of the rotor 26, which has axially parallel pins as holders 45, 46 for the planet carrier 38 and the ring gear 21. Fig.2) Pins as holders 45, 46 are not essential for the invention. The holders 45, 46 extend through mounting openings 47 in the end wall 25 of the hollow shaft 26. The planet carrier 38 and the ring gear 21 have holes corresponding to their respective holders 45, 46. The planet carrier 38, with the planet gears 17 rotatably mounted on it, is placed from inside the hollow shaft 26 onto the holders 45 of the mounting tool 44, and the ring gear 21 is also placed from inside the hollow shaft 26 onto its respective holders 46 of the mounting tool 44. The mounting tool 44 has a hollow cylindrical hub 48 with which it is mounted on the rotary bearing 33, which is pressed onto the shaft 23. This centers the mounting tool 44 on the hollow shaft 26. If the rotary bearing 23 is pressed on later, the assembly tool 44 can be centered on the shaft 23 or in some other way on the hollow shaft 26 (not shown).The assembly tool 44 holds the planet carrier 38 and the ring gear 21 in a predetermined angular position, allowing the power transmitter 13 and the spindle nut 7 to be inserted into the hollow shaft 26 from the inside of the rotor 26. The positive locking connections 40, 42 between the spindle nut 7 and the planet carrier 38, and between the power transmitter 13 and the ring gear 21, are closed, and the planet carrier 38 is connected to the spindle 7 and the ring gear 21 is connected to the power transmitter 13 in a rotationally fixed manner. The power transmitter 13 can be screwed to the flange part 15 before insertion into the hollow shaft 26, or the flange part 15 can be screwed to the power transmitter 13 after insertion. The assembly tool 44 can be used to hold the power transmitter 13 in a rotationally fixed position for screwing to the flange part 15.After the planetary gear 22, the spindle nut 7 and the power transmitter 13 have been installed in the hollow shaft 26, the assembly tool 44 is pulled out axially.
Claims
[1] Pressure generator for a hydraulic vehicle brake system, comprising a piston-cylinder unit (2) having a cylinder (4) and a piston (3) which is displaceable in the cylinder (4), comprising a screw drive (8) comprising a rotatable, axially fixed, threaded component (7) and an axially displaceable, rotationally fixed component (6) having a mating thread, which is axially fixed to the piston (3) of the piston-cylinder unit (2) and whose mating thread engages with the thread of the rotatable component (7) of the screw drive (8), such that a rotary drive of the rotatable component (7) of the screw drive (8) displaces the axially displaceable component (6) of the screw drive (8) and the axially fixed piston (3) of the piston-cylinder unit (2) with the axially displaceable component (6) of the screw drive (8), characterized bythat the pressure generator (1) has a hollow force transmitter (13) in which at least a portion of a length of the screw drive (8) is arranged and which transmits an axial force, causing pressure generation with the piston-cylinder unit (2), between the piston (3) of the piston-cylinder unit (2) and the rotatable component (7) of the screw drive (8), and that the pressure generator (1) has a planetary gear (22) for a rotary drive of the rotatable component (7) of the screw drive (8), which is arranged coaxially to the screw drive (8) at one end of the screw drive (8) furthest from the piston-cylinder unit (2), wherein a planet carrier (38) of the planetary gear (22) is non-rotatably connected to the rotatable component (7) of the screw drive (8) by a positive-locking connection (40) which can be axially placed onto the rotatable component (7) of the screw drive (8), and wherein a ring gear (21) of the planetary gear (22) by a positive locking connection (42),which can be inserted axially into the force transmitter (13) and is connected to the force transmitter (13) in a rotationally fixed manner. [2] Printing generator according to claim 1, characterized by , that at least one of the positive locking connections (40, 42) has an eccentric axially parallel pin (41, 43) that engages in a hole. [3] Printing generator according to claim 2, characterized by , that at least one of the positive locking connections (40, 42) has several eccentric and axially parallel pins (41, 43) which are arranged distributed over a circumference and engage in holes. [4] Printing generator according to claim 1, characterized by , that the rotatable component (7) of the screw drive (8) is a spindle nut and the axially displaceable component (6) of the screw drive (8) is a spindle. [5] Printing generator according to claim 1, characterized by, that the screw drive (8) is a rolling screw drive with rolling elements (9) via which the thread of the rotatable component (7) engages with the counter thread of the axially displaceable component (6) of the screw drive (8). [6] Printing generator according to claim 1, characterized by , that the pressure generator (1) has an electric hollow shaft motor (27) for rotary drive of the planetary gear (22) with a cup-shaped hollow shaft (26) which encloses the planetary gear (22) and at least part of a length of the screw gear (8), wherein the hollow shaft (26) has an end wall (25) with mounting openings (47) on one side of the planetary gear (22) furthest from the piston-cylinder unit (2), and that a sun gear (20) of the planetary gear (22) is rotationally fixed to the hollow shaft (26). [7] Assembly tool for a planetary gear (22) of a printing press (1) according to claim 6, characterized by, that the assembly tool (44) has holders (45, 46) for the planet gears (17) and the ring gear (21) of the planetary gear (22), which hold the planet gears (17) and the ring gear (21) in the correct position through the assembly openings (47) in the end wall (25) of the hollow shaft (26) of the electric hollow shaft motor (27) and that the assembly tool (44) can be pulled out of the planetary gear (22) through the assembly openings (47) in the end wall (25) of the hollow shaft (26) of the electric hollow shaft motor (27). [8] Method for assembling a printing device (1) according to claim 6, characterized by, that the planet gears (17) of the planetary gear (22) with the planet carrier (38) and the ring gear (21) in the hollow shaft (26) of the electric hollow shaft motor (27) are arranged on holders (45, 46) of an assembly tool (44), which extends through the assembly openings (47) in the end wall (25) of the hollow shaft (26), that the power transmitter (13) and the screw drive (8) are inserted into the hollow shaft (26) of the electric hollow shaft motor (27) in the correct angular alignment, so that the positive locking connection (40) of the planet carrier (38) engages with the rotatable component (7) of the screw drive (8) and the positive locking connection (42) of the ring gear (21) of the planetary gear (22) engages with the power transmitter (13), and that the assembly tool (44) is then inserted through the assembly openings (47) in the end wall (25) the hollow shaft (26) of the electric hollow shaft motor (27) is pulled out.