Motor shaft arrangement of a hydraulic unit of a vehicle braking system

Abstract

Motor shaft arrangement (70) of a hydraulic unit (10) of a vehicle brake system, in which a motor shaft (26) is rotatably mounted on an A-bearing (48), a B-bearing (50) and a C-bearing (52), wherein one of the bearings is arranged with a specifically designed eccentricity (74) to the other two bearings, wherein each of the other two bearings, viewed in its cross-section, has a bearing center and an imaginary connecting line between the two bearing centers defines a geometric axis (68), wherein the specifically designed eccentricity (74) is formed in the form of an opening which has an opening center axis (78) radially spaced from the geometric axis (68) and in the opening a bearing is arranged eccentrically compared to the other bearings, wherein the eccentricity (74) is determined by a distance between the opening center axis (78) and the geometric axis (68), characterized in that that the specifically designed eccentricity (74) is created by means of an eccentric sleeve (82, 90) on the C-bearing (52), or that the specifically designed eccentricity (74) is created by means of an eccentric inner ring (122) on the B-bearing (50), or that the specifically designed eccentricity (74) is created by means of an eccentric outer ring (114) on the B-bearing (50).

Description

State of the art

[0001] The invention relates to a motor shaft assembly of a hydraulic unit of a vehicle braking system, in which a motor shaft is rotatably mounted on an A-bearing, a B-bearing, and a C-bearing. The invention further relates to a method for manufacturing such a motor shaft assembly and to the use of such a motor shaft assembly in a hydraulic unit of a vehicle braking system.

[0002] Hydraulic power units are used in the braking systems of motor vehicles, such as passenger cars or trucks, to provide controlled brake pressure in the associated brake circuits using brake fluid. In particular, they enable the functions of an anti-lock braking system (ABS) and / or an electronic stability program (ESP). Known hydraulic power units comprise a hydraulic block or a block-shaped housing with several bores. This housing also serves as a pump housing for associated pump elements, each containing a pump piston that is moved back and forth within a pump cylinder by means of an eccentric drive. The eccentric drive is powered by a motor shaft that is centrally mounted in a bore of the hydraulic block and is coupled to a drive motor. The drive motor is mounted externally on the hydraulic block by a motor housing.

[0003] During operation, vibrations occur that can cause noise and thus negatively affect the vehicle's NVH (Noise, Vibration, Harshness) characteristics. NVH describes unwanted vibrations that are audible as noise or perceptible as vibration. Especially during maneuvers that are particularly noticeable to the driver, the drive motor and the entire vehicle braking system must operate very quietly. Quiet operation is essential, for example, with adaptive cruise control (ACC).

[0004] To reduce such noise, the motor shaft is conventionally supported by three bearings: an A-bearing, a B-bearing, and a C-bearing. The A-bearing acts as the main bearing, supporting the motor shaft within the bore of the hydraulic block at a transition to an interior space of the motor housing. The B-bearing supports one end of the motor shaft against the motor housing, and the C-bearing supports the other end within the hydraulic block. A motor shaft arrangement featuring such a three-bearing motor shaft is known from US Patent 2008 / 0174192A1.

[0005] Various eccentrically designed bearings are known from US 5 362 158 A, DE 10 2009 052 072 A1 and FR 575 321 A.

[0006] US 5 811 902 A discloses a motor shaft arrangement in which eccentrically acting loads are transferred to associated bearings by means of eccentrically acting springs.

[0007] From DE 41 18 950 A1, a motor shaft arrangement is known in which a drive shaft is guided eccentrically along its entire length in the bearing of an associated housing by means of two eccentrically designed bearing rings. The two bearing rings are conformal in their eccentricity with respect to both magnitude and direction. Disclosure of the invention

[0008] According to the invention, a motor shaft arrangement of a hydraulic unit of a vehicle braking system, in which a motor shaft is rotatably mounted on an A-bearing, a B-bearing and a C-bearing, is provided according to claim 1. One of the bearings is arranged with a specifically designed radial eccentricity relative to the other two bearings.

[0009] Each of the other two bearings has a bearing center point in its cross-section. Connecting these two bearing centers defines a geometric axis. According to the invention, the additional bearing is arranged eccentrically relative to this geometric axis. Eccentric means outside the center defined by the geometric axis of the other two bearings. With such an eccentric bearing arrangement, a slightly curved, real axis is formed along which the motor shaft is installed and supported, differing from the strictly straight geometric axis. Because the real axis of the motor shaft deviates from the geometric axis in the radial direction, the motor shaft is radially preloaded, and play in the bearings involved is significantly reduced compared to a strictly concentric arrangement of the three bearings. This further restricts the radial freedom of movement of the motor shaft.Furthermore, the motor shaft is unevenly supported around its circumference by the eccentric bearing arrangement according to the invention, thus damping its radial movements unevenly and at specific points around its circumference. This damping prevents resonance that would otherwise occur. The eccentricity of the bearing arrangement, as designed according to the invention, also allows the radial movements of the motor shaft to be damped selectively, depending on the available installation space and / or motor power. This enables the reliable and targeted absorption of lateral forces acting on the motor shaft during operation of the drive motor. This absorption significantly improves the NVH (noise, vibration, and harshness) behavior compared to conventionally arranged bearings and substantially extends the service life of the components involved.

[0010] The lateral forces acting on the motor shaft during operation arise both from the reciprocating movement of each individual pump piston, which is supported on the motor shaft via the eccentric drive, and from the rotation of an armature belonging to the drive motor. The armature is either connected to the motor shaft or formed as a single unit, thus driving the motor shaft to rotate around its axis by rotating the armature. The armature, as part of the rotor of the electric drive motor, rotates within a magnetic field as the stator, along with its associated current-carrying coil winding. This rotation generates electromagnetic forces that act as lateral forces on the armature and are transmitted, as so-called armature forces, to the motor shaft and other components of the hydraulic unit.

[0011] Conventionally, the motor shaft is excited to oscillate radially by such lateral forces during rotation. As discovered according to the invention, this is due to the fact that the bearings supporting the motor shaft are arranged as concentrically as possible to one another. This results in the bearings having the smallest possible concentricity offset relative to each other. The smaller the concentricity offset, that is, the more ideally the bearings are aligned with their respective bearing surfaces, the more play the rotating armature of the motor and the motor shaft have in the bearings. Such play means that vibrations occurring in the radial direction are not damped within a certain range of this play. If the motor shaft is deflected beyond this range of play, it is supported uniformly around its circumference by the bearings.Evenly supported, the vibrations of the motor shaft can be further amplified by any resonance that may occur. Furthermore, the armature forces are transmitted impulsively due to backlash. This transmission significantly increases and negatively impacts NVH (noise, vibration, and harshness). Additionally, all components involved are subjected to very high loads. The solution according to the invention largely avoids all of these conventional disadvantages.

[0012] According to the invention, the deliberately designed eccentricity is formed in the form of an opening, in particular a bore, in the hydraulic unit, which has an opening axis radially spaced from the geometric axis. In such an opening, a bearing is then arranged eccentrically compared to the other bearings, the eccentricity being determined by a distance between the opening axis and the geometric axis. Furthermore, and particularly preferably, a radially eccentric ring and / or a radially eccentric bearing can be inserted into an existing opening, which is generally concentric with the geometric axis. An eccentrically designed ring and / or bearing has an outer shell with an outer shell axis and an inner shell with an inner shell axis, which are distinct from one another.The eccentricity is determined by the distance between the inner and outer shell centerlines. By varying this distance, the eccentricity can be precisely controlled.

[0013] According to the invention, the eccentricity is advantageously dimensioned to be between 0.02 and 0.80 millimeters, preferably between 0.05 and 0.60 millimeters. The eccentricity is defined as the distance between the geometric axis formed by the two other bearings and the actual axis at the level of the one eccentrically arranged bearing. The actual axis passes either through the center point of a cross-section of an eccentrically arranged opening located on the central axis of the opening, or through the center point of a cross-section of an eccentrically designed bearing and / or ring located on the central axis of the inner shell. This distance, and thus the eccentricity, is specifically set according to the invention to be between 0.02 and 0.80 millimeters, preferably between 0.05 and 0.60 millimeters. This reliably clamps the motor shaft against unwanted radial excitation and / or radial play without restricting its rotation or rotational movement.

[0014] Preferably, the precisely engineered eccentricity can be varied in intervals or steps of 0.05 millimeters to allow the use of existing components, particularly known sleeves, for manufacturing the eccentric bearing arrangement. Furthermore, this allows the precisely engineered eccentricity or a specific concentricity offset to be adjusted as required.

[0015] Furthermore, the specifically designed eccentricity is created according to the invention by means of a radially eccentric sleeve on the C-bearing. The motor shaft is supported at one end in the hydraulic block at the C-bearing and clamped to the C-bearing by means of the eccentric sleeve. Such a clamping action is particularly stable because the hydraulic block is a solid block that can absorb clamping forces across a wide range of magnitudes, especially without changing its position.

[0016] Furthermore, the eccentric sleeve is preferably arranged as an additional sleeve simply around an existing or known C-bearing. For this purpose, the additional eccentric sleeve has an inner diameter that surrounds the existing C-bearing at its outer diameter. This allows for the cost-effective use of an existing C-bearing, and the opening provided on the hydraulic block for receiving the C-bearing can be easily enlarged and adapted to the additional eccentric sleeve. Furthermore, the additional eccentric sleeve is particularly preferably selected from a group of differently eccentric sleeves, depending on the required eccentricity, so that a required eccentricity can be achieved particularly easily in manufacturing. The C-bearing is preferably a plain bearing, and more preferably a rolling bearing, in particular a needle bearing.

[0017] Particularly preferred is the eccentric sleeve on the C-bearing already formed during the manufacturing of the C-bearing. For this purpose, in both a plain bearing with an inner ring and an outer ring, and in a needle bearing used as a C-bearing, the outer ring or the outer sleeve is designed eccentrically. With this design, no additional component is required to achieve the eccentricity according to the invention. Furthermore, with a suitable arrangement of the motor shaft, such a C-bearing can then be installed in an existing installation space.

[0018] Alternatively, in the motor shaft arrangement according to the invention, the precisely designed eccentricity is achieved by means of a radially eccentric inner ring on the B-bearing. This B-bearing supports the motor shaft at the end on the motor housing opposite the end supported by the C-bearing. This clamps the motor shaft to the motor housing, which can absorb the clamping forces occurring during operation in a material-friendly manner, distributing them evenly across the entire motor housing. Furthermore, the eccentricity of the B-bearing can be adjusted as required and with a precise fit by selecting the B-bearing from a group of B-bearings with differently eccentric inner rings. Preferably, the B-bearing is a plain bearing, in particular a sliding bushing, designed with an eccentric inner ring. This allows the motor shaft to be clamped in a particularly compact and stable manner.

[0019] Alternatively, in the motor shaft arrangement according to the invention, the specifically designed eccentricity is achieved by means of a radially eccentric outer ring on the B-bearing. The B-bearing supports the motor shaft, as described, on the motor housing, specifically at the end of the motor shaft opposite the end supported by the C-bearing. According to the invention, the motor shaft is also clamped to the motor housing with particular stability by means of an eccentric outer ring of the B-bearing, since any clamping forces occurring here can be absorbed across the entire motor housing. The eccentricity of the outer ring on the B-bearing can also be varied as required and precisely fitted by selecting the B-bearing from a group of B-bearings with differently eccentric outer rings. The B-bearing can be designed as a plain bearing, in particular as a plain bearing bushing, or as a roller bearing, in particular as a ball bearing.

[0020] Furthermore, the invention is also directed to a method for manufacturing a motor shaft assembly, in particular of this type, for a hydraulic unit of a vehicle braking system according to claim 3, comprising the steps of: providing a motor shaft, providing those components on which the motor shaft is rotatably mounted by means of an A-bearing, a B-bearing, and a C-bearing, measuring the motor shaft with regard to its installation position on the bearings, providing a specifically designed eccentricity at one of the bearings relative to the other two bearings, and arranging the motor shaft on such bearings. With such a method, the motor shaft can be clamped in the hydraulic unit in a targeted manner by creating a specific eccentricity. Depending on the desired design, in particular with regard to the number of bearing positions, as well as depending on the desired application and the NVH behavior to be achieved, the eccentricity can be adjusted as required.The required lifespan or operating time can also be specifically addressed.

[0021] Preferably, the motor shaft is measured once with regard to its installation position at the bearings, and then the specifically designed eccentricity is dimensioned accordingly at one of the bearings relative to the other two bearings. This one bearing then has a fixed eccentricity. This allows high quantities of the motor shaft assembly according to the invention to be manufactured in a particularly short time.

[0022] When measuring the motor shaft with regard to its installation position at the bearings, it is particularly advantageous to also measure the components on which the motor shaft is rotatably mounted by means of an A-bearing, a B-bearing, and a C-bearing. Key components for this purpose include, in particular, a pole housing of the drive motor, a cover of the motor housing, a seat for the respective bearing, and / or the hydraulic block as the pump housing. After measuring these components, one bearing is paired accordingly relative to the other two bearings based on the different available eccentricities.

[0023] According to the invention, providing a precisely defined eccentricity comprises selecting a sleeve from a group of differently eccentric sleeves and arranging the sleeve on the C-bearing. This allows the C-bearing's eccentricity to be adjusted particularly easily and precisely. Specifically, the differently eccentric sleeves each have an offset of 0.05 millimeters in their eccentricity. With such a small offset, the exact eccentric sleeve that securely clamps the motor shaft in the hydraulic block with exceptional precision can be selected as needed.

[0024] Alternatively, according to the invention, providing a specifically designed eccentricity also includes selecting the B-bearing with an inner ring from a group of B-bearings with differently eccentric inner rings and arranging this B-bearing. The differently eccentric inner rings preferably also have an offset in their eccentricity from one another in intervals of 0.05 millimeters each, in order to enable precise adjustment of the eccentricity. Preferably, a plain bearing is used as the B-bearing.

[0025] In a further alternative according to the invention, providing a specifically designed eccentricity comprises selecting the B-bearing with an outer ring from a group of B-bearings with differently eccentric outer rings and arranging this B-bearing. Here, "outer ring" is understood to mean, in particular, both an outer ring of a plain bearing and an outer ring of a rolling bearing, especially a roller bearing. In the group of B-bearings with differently eccentric outer rings, the eccentric outer rings are also offset from each other by approximately 0.05 millimeters in their eccentricity.

[0026] Furthermore, the invention also relates to the use of such a motor shaft arrangement for mounting a motor shaft on a hydraulic unit of a vehicle braking system. By means of the motor shaft arrangement according to the invention, radial vibrations of the motor shaft in its bearings are particularly strongly damped, thus achieving a particularly low-vibration hydraulic unit. With such a hydraulic unit, a particularly low-vibration and low-noise vehicle braking system is created.

[0027] Exemplary embodiments of the solution according to the invention are explained in more detail below with reference to the accompanying schematic drawings. These show: Fig. 1 a longitudinal section of a hydraulic power unit with a motor shaft arrangement according to the state of the art, Fig. 2 a highly schematic representation of the motor shaft arrangement according to Fig. 1, Fig. 3 the view according to Fig. 2 of a first embodiment of a motor shaft arrangement according to the invention, Fig. 4 the view according to Fig. 2 of a second embodiment of a motor shaft arrangement according to the invention, Fig. 5 the detail V according to Fig. 4 with a first variant of the second embodiment, Fig. 6 the detail V according to Fig. 4 with a second variant of the second embodiment, Fig. 7 detail V according to Fig. 4 with a third variant of the second embodiment, Fig. 8 the view according to Fig. 2 of a third embodiment of a motor shaft arrangement according to the invention, Fig. 9 the view according to Fig. 2 of a fourth embodiment of a motor shaft arrangement according to the invention, Fig. 10 the detail X according to Fig. 9 with a first variant of the fourth embodiment and Fig. 11 the detail X according to Fig. 9 with a second variant of the fourth embodiment.

[0028] Fig. Figure 1 shows a hydraulic unit 10 of a vehicle braking system not shown further, which in particular enables an anti-lock braking system, an anti-slip system and a vehicle dynamics control function (ABS, ASR and ESP).

[0029] The hydraulic unit 10 comprises a cuboid hydraulic block 12 (only partially shown) as a block-shaped pump housing and a drive motor 14 attached to the outside of it. The drive motor 14 has a cup-shaped motor housing 16, which is attached in a conventional manner to a side surface of the hydraulic block 12 with at least two screws 18, thus holding the drive motor 14 to the hydraulic block 12.

[0030] The drive motor 14 is an electric motor and comprises, as its rotor, an armature 20 with a current-carrying coil winding 22, which rotates in a stator 24 when an electrical voltage is applied. This drives a motor shaft 26, which is coupled to the armature 20 for power transmission, to rotate about its shaft axis 28. The motor shaft 26 also projects through a bore 30 into the hydraulic block 12 and is coupled there for power transmission to an eccentric bearing 32, on which several pump pistons 36, each guided in a pump cylinder 34, are supported. Thus supported, when the motor shaft 26 rotates, each individual pump piston 36 is moved back and forth along its piston axis 38 in the corresponding pump cylinder 34 by means of the eccentric bearing 32 acting as an eccentric drive.In a known manner, a hydraulic fluid, in this case brake fluid, is drawn into the pump cylinder 34 via an inlet valve 40 and pressurized as the pump piston 36 moves into the pump cylinder 34. The pressurized hydraulic fluid is then expelled from the pump cylinder 34 via an outlet valve 42 into hydraulic lines (not shown) of the associated vehicle braking system to perform work. The individual pump cylinder 34, together with the associated pump piston 36, the inlet valve 40, the outlet valve 42, and other known components not explicitly mentioned here, each forms a single pump element 44.

[0031] Both during the rotation of the armature 20 and during the reciprocating movement of the individual pump piston 36, lateral forces are exerted on the motor shaft 26. These lateral forces cause the motor shaft 26 to vibrate and move radially to the shaft axis 28, resulting in undesirable vibrations and movements that generate unwanted noise and are also known as structure-borne sound excitation.

[0032] To limit such radial movements, in a conventional motor shaft arrangement 46 the motor shaft 26 is supported in three ways by an A-bearing 48, a B-bearing 50 and a C-bearing 52.

[0033] The A-bearing 48, or first motor shaft bearing, supports the motor shaft 26 in the bore 30 of the hydraulic block 12 at a transition between the hydraulic block 12 and a motor interior 54 enclosed by the motor housing 16 and hydraulic block 12. Adjacent to the A-bearing 48, the eccentric bearing 32 is arranged on the motor shaft 26 within the hydraulic block 12. Thus, the A-bearing 48 is subjected to the greatest lateral forces during the translational movement of the individual pump piston 36, making it the main bearing. For this purpose, the A-bearing 48 is designed as a deep groove ball bearing.

[0034] The B-bearing 50, or second motor shaft bearing, supports the motor shaft 26 at one end 56 against the motor housing 16 in a B-bearing seat 57. The B-bearing 50 is positioned closest to the armature 20 compared to the other two bearings 48 and 52. This ensures that the B-bearing 50 absorbs the transverse forces acting on the motor shaft 26 during rotation of the armature 20, known as armature forces. The B-bearing 50 is designed as a plain bearing.

[0035] The C-bearing 52 or third motor shaft bearing further supports the motor shaft 26 at an end area 58 opposite the end area 56 in the hydraulic block 12 and is designed as a needle bearing in this case.

[0036] Both the B-bearing 50 and the C-bearing 52 are designed as floating bearings, meaning that the motor shaft 26 is mounted there in a way that allows axial displacement.

[0037] Fig. 1 and Fig. Figure 2 shows that all three bearings 48, 50, and 52 of the motor shaft assembly 46 are conventionally arranged concentrically to one another in a bearing arrangement 60. For this purpose, bearing A 48 has an A-bearing center point 62 in a cross-section that bisects its associated A-bearing axis, bearing B 50 has a B-bearing center point 64 in a cross-section that bisects its associated B-bearing axis, and bearing C 52 has a C-bearing center point 66 in a cross-section that bisects its associated C-bearing axis. All three bearing centers 62, 64, and 66 lie on an imaginary geometric axis 68, which coincides with the shaft axis 28 of the motor shaft 26. Thus, the motor shaft 26 is also arranged concentrically to and within the three bearings 48, 50, and 52. When arranged in this way, the motor shaft 26 has a certain amount of play or radial freedom of movement in its three bearings 48, 50 and 52.Increased play is particularly evident in the two draw camps, that is, in the B-camp 50 and the C-camp 52.

[0038] With such clearance in the conventional, concentric bearing arrangement 60, the radial vibrations of the motor shaft 26 caused by the transverse forces occurring during operation are not damped at all within a certain range. If this range is exceeded, that is, if the motor shaft 26 encounters a bearing core during its radial movements, the motor shaft 26 is damped uniformly along its entire circumference. This means that any vibration resonance that may occur cannot be sufficiently suppressed. Overall, this results in undesirable vibrations and noise, so that the NVH behavior in the hydraulic unit 10 is unsatisfactory with the conventional bearing arrangement 60.

[0039] In contrast, the Fig. 3 to Fig. 11 a motor shaft arrangement 70 according to the invention. In a bearing arrangement 72 or 73, a bearing with a specifically designed eccentricity 74 is positioned eccentrically to the two other bearings, which define an imaginary geometric axis 68. In such a bearing arrangement 72 or 73, the motor shaft 26 is supported in the three bearings 48, 50, and 52 and has a slightly curved shaft axis 28 as its actual axis. Thus, the shaft axis 28 differs from the geometric axis 68, whereby the motor shaft 26 is held under tension in the three bearings 48, 50, and 52. Held under tension in this way, the motor shaft 26 is severely restricted in its radial freedom of movement. Any radial transverse forces that occur are transmitted in a stable manner by the massive hydraulic block 12 ( Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. 7) or over a wide area of ​​the engine housing 16 ( Fig. 8, Fig. 9, Fig. 10 to Fig. 11). This results in particularly good NVH behavior. For clarity, neither the clamped motor shaft 26 nor its shaft axis 28 are shown in the figures.

[0040] The specifically designed eccentricity 74 is furthermore set in the range of 0.05 to 0.60 millimeters as required and varied in eccentricity increments or intervals of 0.05 millimeters.

[0041] Fig. 3 to Fig. Figure 7 represents the bearing arrangement 72, in which the C-bearing 52 is arranged eccentrically to the other two bearings, i.e., to the A-bearing 48 and the B-bearing 50. The A-bearing center 62 and the B-bearing center 64, already described, together with their imaginary connecting line, form the geometric axis 68, with respect to which the C-bearing 52 is positioned eccentrically.

[0042] According to Fig. In section 3, the C-bearing 52 itself is designed to be central, but is offset from the geometric axis 68 by a distance of the specifically formed eccentricity 74. For this purpose, an opening section 76 is provided in the bore 30, the central axis 78 of which runs at the distance, or with the specifically formed eccentricity 74, from the geometric axis 68. The central C-bearing 52 is inserted concentrically into this opening section 76, so that its bearing center 66 is spaced from the geometric axis 68 by the specifically formed eccentricity 74. The bearing center 66 is part of the shaft axis 28 as a real axis, thus specifically clamping the associated motor shaft 26.

[0043] According to Fig. 4 to Fig. In section 7, the opening section 76 of the bore 30 is positioned concentrically to the geometric axis 68, while the C-bearing 52 inserted there is designed eccentrically overall. Designed in this way, the C-bearing 52 has an inner central axis 80 and an outer central axis, which are distinct from each other. The outer central axis is coincident with the geometric axis 68, while the inner central axis 80 is spaced apart from it by the specifically designed eccentricity 74. On the inner central axis 80, in a cross-section that bisects the height of the C-bearing 52, lies an inner center point 81, which is part of the shaft axis 28 as the actual axis. This ensures that the motor shaft 26 is also specifically preloaded. Fig. Figure 4 shows a highly schematic representation of the overall eccentrically designed C-bearing 52.

[0044] Fig. Figure 5 shows in more detail a variant of the overall eccentrically designed C-bearing 52 according to Fig. 4. The C-bearing 52 itself is initially designed to be concentric, and in this case, a conventional C-bearing 52 has been used. This C-bearing 52 is additionally surrounded by an eccentric sleeve 82, which comprises an inner sleeve 84 and an outer sleeve 86 arranged eccentrically to it. The inner sleeve 84 has an inner diameter 88 that corresponds to the outer diameter of the C-bearing 52. The eccentric sleeve 82 is simply pressed onto the conventional C-bearing 52 as an additional sleeve. The eccentric sleeve 82 is selected from a group of differently eccentric sleeves 82, thus allowing for a specific eccentricity 74 to be set as required. Such a specifically designed eccentricity 74 corresponds to the distance of the geometric axis 68 from a central axis of the inner sleeve 84, which is identical to the inner central axis 80 of the C-bearing.Furthermore, the opening section 76 of the bore 30, positioned concentrically to the geometric axis 68, was concentrically enlarged to correspond to a sleeve outer diameter 89. In this way, a known C-bearing 52 could be used.

[0045] In an alternative variant not shown, the C-bearing 52 can be eccentrically designed and, in order to vary the specifically designed eccentricity 74, can additionally be surrounded by an eccentric sleeve 82 and / or several eccentric sleeves 82.

[0046] In Fig. Figure 6 details a further variant of the overall eccentrically designed C-bearing 52 according to Fig. Figure 4 illustrates this. The C-bearing 52 itself is eccentrically designed as a needle roller bearing with an eccentric outer ring 90, which is arranged around a concentric inner ring 92 made of needles. The eccentric outer ring 90 has an outer outer shell 94 and an inner outer shell 96, the central axes of which are spaced apart by a specifically designed eccentricity 74. The central axis of the inner outer shell 96 is coincident with the inner central axis 80 of the C-bearing, and the central axis of the outer outer shell 94 is coincident with the geometric axis 68. Designed in this way, the eccentrically designed C-bearing 52 can be manufactured with a precise fit and easily installed in an existing, conventional, concentric opening section 76.

[0047] Fig. Figure 7 shows in detail another variant of the overall eccentrically designed C-bearing 52 according to Fig. 4, which itself is eccentrically designed, this time as a plain bearing bushing with a concentric outer ring 98 and an eccentric inner ring 100. The eccentric inner ring 100 comprises an inner ring outer shell 102 and an inner ring inner shell 104, the central axes of which have a distance from each other of the specifically designed eccentricity 74. The central axis of the inner ring inner shell 104 corresponds to the C-bearing inner central axis 80, and the central axis of the inner ring outer shell 102 corresponds to the geometric axis 68. Even with this variant, the C-bearing 52 can be manufactured with a precise fit and inserted into the conventional opening section 76.

[0048] Fig. 8 to Fig. Figure 11 illustrates the bearing arrangement 73, in which the B-bearing 50 is arranged eccentrically to the other two bearings, i.e., to the A-bearing 48 and the C-bearing 52. In this case, the previously described A-bearing center point 62 and the C-bearing center point 66, with their imaginary connecting line, form the geometric axis 68, to which the B-bearing 50 is positioned with the specifically designed eccentricity 74.

[0049] According to Fig. In section 8, the B-bearing 50 is conventionally designed centrally and arranged in a B-bearing seat 57 on the motor housing 16, the associated bearing seat center axis 106 being spaced from the geometric axis 68 by the specifically designed eccentricity 74. The B-bearing center point 64 lies on the bearing seat center axis 106 and on the shaft axis 28, thus the B-bearing 50 is arranged offset from the geometric axis 68 and the motor shaft 26 is clamped.

[0050] In Fig. In contrast, the B-bearing seat 57 is arranged concentrically to the geometric axis 68 in the conventional manner, and the B-bearing 50, shown here in a highly schematic way, is designed eccentrically according to the invention. The B-bearing 50 has an inner central axis 108 and a different outer central axis, which is congruent with the geometric axis 68. A cross-section bisecting the height of the B-bearing 50 defines an inner center point 110 of the B-bearing that lies on the inner central axis 108. The inner center point 110, with its distance to the geometric axis 68, determines the specifically designed eccentricity 74 and is part of the shaft axis 28. This ensures that the motor shaft 26 is preloaded.

[0051] In Fig. 10 is a more detailed variant of such an eccentrically designed B-bearing 50 according to Fig. Figure 9 shows a bearing designed as a roller bearing with an eccentric outer ring 114 surrounding a central inner ring 112. The eccentric outer ring 114 is formed with different central axes of an associated inner outer ring shell 116 and an associated outer outer ring shell 118. The central axis of the outer outer ring shell 118 lies on the geometric axis 68, and the central axis of the inner outer ring shell 116 lies on the B-bearing's inner central axis 108, thus defining the specifically designed eccentricity 74.

[0052] Fig. Figure 11 shows another detailed variant of such an eccentrically designed B-bearing 50 according to Fig.9 with a centric outer ring 120 in which an eccentric inner ring 122 is arranged. The eccentric inner ring 122 comprises an inner ring shell 124 and an inner ring outer shell 126, each with a central axis. The central axis of the inner ring shell 124 is coincident with the inner central axis 108 of the B-bearing, and the central axis of the inner ring outer shell 126 is coincident with the geometric axis 68. The eccentric inner ring 122 is particularly advantageous when the B-bearing 50 is a plain bearing bushing.

Claims

[1] Motor shaft arrangement (70) of a hydraulic unit (10) of a vehicle brake system, in which a motor shaft (26) is rotatably mounted on an A-bearing (48), a B-bearing (50) and a C-bearing (52), wherein one of the bearings is arranged with a specifically designed eccentricity (74) to the other two bearings, wherein each of the other two bearings, viewed in its cross-section, has a bearing center and an imaginary connecting line between the two bearing centers defines a geometric axis (68), wherein the specifically designed eccentricity (74) is formed in the form of an opening which has an opening center axis (78) radially spaced from the geometric axis (68) and in the opening a bearing is arranged eccentrically compared to the other bearings, wherein the eccentricity (74) is determined by a distance between the opening center axis (78) and the geometric axis (68), characterized by , that the specifically designed eccentricity (74) is created by means of an eccentric sleeve (82, 90) on the C-bearing (52), or that the specifically designed eccentricity (74) is created by means of an eccentric inner ring (122) on the B-bearing (50), or that the specifically designed eccentricity (74) is created by means of an eccentric outer ring (114) on the B-bearing (50). [2] Motor shaft arrangement according to claim 1, wherein the specifically designed eccentricity (74) is dimensioned from 0.02 to 0.80 millimeters, preferably from 0.05 to 0.60 millimeters. [3] Method for manufacturing a motor shaft assembly (70) of a hydraulic unit (10) of a vehicle brake system, in particular according to one of claims 1 to 2, comprising the steps: Providing a motor shaft (26), Providing those components on which the motor shaft (26) is to be rotatably mounted by means of an A-bearing (48), a B-bearing (50) and a C-bearing (52), Measuring the motor shaft (26) with regard to its installation position at the bearings (48, 50, 52), Providing a specifically designed eccentricity (74) at one of the bearings relative to the other two bearings and Arranging the motor shaft (26) on such bearings (48, 50, 52), in which the provision of a specifically designed eccentricity (74) includes selecting a sleeve from a group of differently eccentric sleeves (82, 90) and arranging the sleeve on the C-bearing (52) or the provision of a specifically designed eccentricity (74) includes selecting the B-bearing (50) with an inner ring from a group of B-bearings (50) with differently eccentric inner rings (122) and arranging this B-bearing (50) or The provision of a specifically designed eccentricity (74) includes selecting the B-bearing (50) with an outer ring from a group of B-bearings (50) with differently eccentric outer rings (114) and arranging this B-bearing (50). [4] Use of a motor shaft arrangement (70) according to one of claims 1 to 2 for supporting a motor shaft (26) on a hydraulic unit (10) of a vehicle brake system.

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