Hydraulic unit for a vehicle brake system with one bearing

Abstract

Hydraulic unit (10) for a vehicle brake system of a motor vehicle with a hydraulic block (36) and a bearing (22) of a drive motor (12) supported on the hydraulic block (36), in which the bearing (22) is held in a fixed position on the hydraulic block (36) by a first press fit (50), characterized by the fact that the associated drive motor (12) is designed with a brush carrier (56), wherein the brush carrier (56) has at least one radial or axial recess (54) for attaching a press tool (52) to the bearing (22).

Description

State of the art

[0001] The invention relates to a hydraulic unit for a vehicle braking system of a motor vehicle, comprising a hydraulic block and a bearing of a drive motor supported on the hydraulic block. The invention further relates to a method for manufacturing a hydraulic unit for a vehicle braking system of a motor vehicle, in which a bearing of a drive motor is supported on a hydraulic block.

[0002] Hydraulic power units are used in motor vehicles, such as passenger cars or trucks, to provide regulated brake pressures to their braking systems. In particular, these hydraulic power units implement the functions of an anti-lock braking system (ABS), traction control (ASR), and / or electronic stability program (ESP). To meter the brake fluid, each hydraulic power unit has a hydraulic block with several pump pistons or pump elements that are moved by an eccentric. The eccentric is located on a motor shaft, which is driven by a drive motor. For the eccentric to exert the desired pressure force on the pump pistons, the motor shaft must be supported by at least one bearing. This relevant bearing, known as the A-bearing, is located at the interface between the drive motor and the hydraulic block.The bearing is part of the drive motor assembly because this bearing is particularly needed during the assembly of the drive motor to ensure the spatial alignment of the motor shaft within the drive motor.

[0003] This type of bearing is then mounted on the drive motor at its front face, on the so-called motor shield, a disc that laterally encloses the drive motor. The bearing can only be held with high rigidity on this motor shield if the motor shield itself is also very rigid. Such a rigid motor shield can generally only be achieved with a steel material. A motor shield made of plastic, which is desirable for reasons of manufacturing costs and weight, will not always be able to meet the requirements for a sufficiently rigid bearing support.

[0004] It is also known to support this bearing on the hydraulic block, whereby the bearing is then positioned as a floating bearing by being loosely inserted into a corresponding recess on the hydraulic block during the mounting of the drive motor on the hydraulic block. The bearing supported on the hydraulic block in this way as a floating bearing also has the disadvantage that it cannot absorb all the forces that sometimes fluctuate considerably during operation.

[0005] It is an object of the invention to create a hydraulic unit for a vehicle braking system in which sufficiently rigid support of the associated drive shaft is provided in a cost-effective manner under all operating conditions.

[0006] German patent DE 199 27 658 A1 discloses a pump unit comprising an electric motor and a radial piston pump. In this unit, a fixed bearing is pressed into a bearing receptacle in the pump housing, allowing the pump shaft to be pressed into the fixed bearing. Disclosure of the invention

[0007] According to the invention, a hydraulic unit for a vehicle braking system of a motor vehicle is provided with a hydraulic block and a bearing of a drive motor supported on the hydraulic block, in which the bearing is held in a fixed position on the hydraulic block by a first press fit.

[0008] According to the invention, the so-called A-bearing on a hydraulic block or pump housing of a hydraulic unit of a vehicle braking system is not merely guided or designed as a floating bearing. In such a floating bearing, the associated bearing ring or raceway would exhibit axial play and also a small amount of radial play. This play would negatively affect the noise, vibration, and harshness (NVH) characteristics. Furthermore, this play would reduce the efficiency of the supported eccentric.

[0009] Instead, according to the invention, this A-bearing is pressed into the hydraulic block and thus designed as a fixed bearing. Such a fixed bearing is characterized in that its pressed-in bearing ring has neither axial nor radial play. With such a bearing, a cost- and space-optimized design can be realized, which exhibits very good noise and vibration characteristics. Furthermore, this solution according to the invention offers advantages with regard to bearing service life and, in particular, with regard to the efficiency of the pump pistons driven by it.

[0010] The bearing is preferably held in place by a second press fit on a motor shaft of the drive motor, wherein the pressing force required for the second press fit is greater than the pressing force required for the first press fit. Such a bearing can be pressed into the hydraulic block starting from the motor shaft. The pressing operation can therefore be initiated at the motor shaft, making it possible to mount the bearing, along with the entire remaining drive motor, to the hydraulic block.

[0011] In order to mount the bearing according to the invention, in a first, advantageous embodiment of the solution according to the invention, the associated drive motor is designed with a brush carrier on which at least one radially directed recess is formed for attaching a press tool to the bearing. The bearing can then be pressed into a recess on the hydraulic block with a corresponding fit formed there, using a press tool or preferably three radially directed press tools through the brush carrier.

[0012] Alternatively or additionally, the associated drive motor is designed with a commutator having at least one axially oriented recess for attaching a pressing tool to the bearing. The commutator is a polarity reversal device or current reverser within the drive motor. Furthermore, the associated drive motor is preferably designed with an iron core having at least one axially oriented recess for attaching a pressing tool to the bearing. The iron core can also be referred to as an iron core for interacting windings of electrically conductive wires. The aforementioned axial recesses make it possible to press the bearing according to the invention axially into the hydraulic block through the drive motor. This pressing can be carried out, in particular, during or simultaneously with the mounting of the drive motor to the hydraulic block.

[0013] The invention is accordingly also directed to a method for manufacturing a hydraulic unit for a vehicle braking system of a motor vehicle, in which a bearing of a drive motor is supported on a hydraulic block, wherein the bearing is fixed in place on the hydraulic block by a first press fit.

[0014] The bearing is preferably fixed in place by means of a second press fit on a motor shaft of the drive motor, as explained above, wherein the pressing force required for the second press fit is dimensioned to be greater than the pressing force required for the first press fit.

[0015] The first press fit is preferably produced using a press tool through a brush holder of the drive motor. Furthermore, the first press fit is preferably produced using a press tool through a commutator of the drive motor. Alternatively or additionally, the first press fit is produced using a press tool through a winding core of the drive motor.

[0016] An exemplary embodiment of the solution according to the invention is explained in more detail below with reference to the accompanying schematic drawings. It shows: Fig. 1. A hydraulic diagram of a vehicle braking system in accordance with the state of the art, Fig. 2 a section of a hydraulic diagram of a first embodiment of a vehicle braking system according to the invention, Fig. 3 a section of a hydraulic diagram of a second embodiment of a vehicle braking system according to the invention, Fig. 4 an excerpt of a hydraulic diagram of a third embodiment of a vehicle braking system according to the invention and Fig. 5 an excerpt of a hydraulic diagram of a fourth embodiment of a vehicle braking system according to the invention.

[0017] In Fig. Figure 1 shows a hydraulic power unit 10 according to the prior art, comprising a drive motor 12. The drive motor 12 has a cup-shaped motor housing 14, the open end of which is closed by a disc-shaped motor shield 16. A motor shaft 18 projects centrally from the motor shield 16 and extends along an axis 20. A bearing 22 with its inner bearing ring 24 is pressed onto the motor shaft 18. The bearing ring 24 is surrounded by rolling elements 26, which in turn are enclosed on the outside by an outer bearing ring 28. The outer bearing ring 28 is supported radially and axially in the motor shield 16 with respect to the axis 20, with the bearing 22 being held there as a fixed bearing on the motor shield 16. With this fixed bearing support, there is no play between the outer bearing ring 28 and the motor shield 16.Instead, the outer bearing ring 28 is pressed into the openings of the bearing shield and is thus held in place there due to the adhesive forces of the two adjacent surfaces resulting from the pressing.

[0018] An eccentric 30 is arranged on the motor shaft 18, which is rotatably supported on the motor shield 16 in this manner. The eccentric 30 consists of an eccentric cam 32 pressed onto the motor shaft 18 in a rotationally fixed manner and an eccentric bearing 34 surrounding this eccentric cam 32.

[0019] On the end face 38 of an associated hydraulic block 36, to which the drive motor 12 is attached, a stepped shaft bore 40, designed as a blind bore, is formed. The shaft bore 40 projects from the end face 38 into the hydraulic block 36 in the direction of the axis 20 and has two pump element bores 42, which are oriented transversely to the axis 20.

[0020] When attaching the drive motor 12 to the hydraulic block 36, the motor shield 16 is placed against the end face 38 and simultaneously the end of the motor shaft 18 protruding from the motor shield 16, together with the eccentric 30 mounted on it, is inserted into the shaft bore 40. The bearing 22 remains fixedly held outside the shaft bore 40 on the motor shield 16.

[0021] The Fig. Figure 2 shows the assembly of a hydraulic unit in which the bearing 22 is not radially supported on the associated drive motor 12, and in particular not on its motor end shield 16. Instead, in this embodiment according to the invention, the bearing 22 is pressed onto the associated motor shaft 18 in such a way that it projects from the motor end shield 16 in the direction of the shaft bore 40.

[0022] At the interface of the end face 38, a bearing bore 44 with a slightly larger diameter than the diameter of the shaft bore 40 is formed in the shaft bore 40 as a step or shoulder. On the radially inwardly directed cylindrical mating surface 46, in conjunction with an outer cylindrical mating surface 48 on the outer bearing ring 28 of the associated bearing 22, an interference fit 50 is formed, by means of which the bearing 22 is held in a fixed position both axially and radially as a fixed bearing after a press-fit operation in the bearing bore 44.

[0023] The pressing process is carried out using a pressing tool 52, which is designed in the form of arms or punches and engages in corresponding recesses 54 on the drive motor 12. This will be shown below with reference to the Fig. 3, Fig. 4 to Fig. 5 explained in more detail.

[0024] According to Fig. 3 The drive motor 12 used (in addition to its components motor housing and motor shield, which are not shown in detail for the sake of simplicity) is designed with a brush carrier 56, a commutator 58 and an iron core 60. In the embodiment according to Fig. 3 the recesses 54 for inserting the press tool 52 to the bearing 22 in axial direction through the iron pack 60, past the commutator 58 on the outside and then through the brush carrier 56.

[0025] In the embodiment according to Fig. 4 the recesses 54 extend only in a radial direction in the brush carrier 56 on its side facing the hydraulic block 36.

[0026] The Fig. Figure 5 shows an embodiment in which the recesses 54 extend axially through the iron pack 60, the commutator 58 and the brush carrier 56.

[0027] The Fig.Figure 6 shows an alternative method of mounting the drive motor 12 on the hydraulic block 36, simultaneously forming the press fit 50 between the mating surface 46 of the bearing bore 44 and the mating surface 48 of the outer bearing ring 28. In this mounting method, the bearing 22 is first mounted as the A-bearing in the bearing bore 44 on the hydraulic block 36, forming the press fit 50. Subsequently, the rest of the drive motor 12, with its motor shaft 18, is inserted into the bearing 22 thus fixed to the hydraulic block 36. A motor assembly 62, comprising the components iron core 60, commutator 58, and brush holder 56, as well as a bearing 64 as the B-bearing, are already attached to the motor shaft 18. The motor shaft 18 then protrudes from the bearing 22 on the side facing away from the drive motor 12. At this protruding end area of ​​the motor shaft 18, a bearing 66 is then pushed onto the assembly as a C-bearing with a loose fit to complete the assembly process.Mounted in this manner, bearings 64 and 66 form the floating bearings on the motor shaft 18, while bearing 22, as a fixed bearing, fixes the motor shaft 18 in close proximity to the eccentric 30 in both radial and axial directions.

Claims

[1] Hydraulic unit (10) for a vehicle brake system of a motor vehicle comprising a hydraulic block (36) and a bearing (22) of a drive motor (12) supported on the hydraulic block (36), in which the bearing (22) is held in a fixed position on the hydraulic block (36) by a first press fit (50), characterized by , that the associated drive motor (12) is designed with a brush carrier (56), wherein the brush carrier (56) has at least one radial or axial recess (54) for attaching a press tool (52) to the bearing (22). [2] Hydraulic unit according to claim 1, wherein the bearing (22) is held in a fixed position on a motor shaft of the drive motor (12) by means of a second press fit, wherein the pressing force required for the second press fit is greater than the pressing force required for the first press fit (50). [3] Hydraulic unit according to one of claims 1 or 2, wherein the associated drive motor (12) is designed with a commutator (58) on which at least one axially directed recess (54) for attaching a press tool (52) to the bearing (22) is formed. [4] Hydraulic unit according to one of claims 1 to 3, wherein the associated drive motor (12) is designed with an iron core (60) on which at least one axially directed recess (54) is formed for attaching a press tool to the bearing (22). [5] Method for manufacturing a hydraulic unit for a vehicle brake system (10) of a motor vehicle, in which a bearing (22) of a drive motor (12) is supported on a hydraulic block (36), wherein the bearing (22) is fixed in place on the hydraulic block (36) by a first press fit (50), characterized by, that the associated drive motor (12) is designed with a brush carrier (56), wherein the brush carrier (56) has at least one radial or axial recess (54) and wherein a press tool (52) engages in the recess (54) for attachment to the bearing (22). [6] Method according to claim 5, wherein the bearing (22) is fixed in place by a second press fit on a motor shaft of the drive motor (12), wherein the press-in force required for the second press fit is dimensioned to be greater than the press-in force required for the first press fit (50). [7] Method according to claim 5 or 6, wherein the first press fit (50) is produced by a press tool (52) through a brush carrier (56) of the drive motor (12). [8] Method according to any one of claims 5 to 7, wherein the first press fit (50) is produced with a press tool (52) through a commutator (58) of the drive motor (12). [9] Method according to any one of claims 5 to 7, wherein the first press fit (50) is produced by a press tool (52) through an iron pack (60) of the drive motor (12).

Images