EP2567111A1

EP2567111A1 - Eccentric bearing

Info

Publication number: EP2567111A1
Application number: EP11709092A
Authority: EP
Inventors: Juergen Haecker; Norbert Alaze
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-05-05
Filing date: 2011-03-10
Publication date: 2013-03-13
Also published as: CN102884327A; CN102884327B; US8950942B2; JP2013525710A; US20130195390A1; DE102010028581A1; WO2011138073A1

Abstract

The invention relates to an eccentric bearing (1) for an electrohydraulic piston pump assembly of a vehicle brake system. The invention proposes the provision of a shaft (2) which can be driven in rotation about its axis (6), a bearing ring (3) which is eccentric with respect to the shaft (2), and rolling bodies (5) between the bearing ring (3) and the shaft (2), which rolling bodies have different diameters corresponding to a varying width of a gap (4) between the bearing ring (3) and the shaft (2). When the shaft (2) is driven in rotation, an eccentricity of the bearing ring (3) revolves around the shaft (2) at half of the rotational speed of the latter and drives pump pistons (9), which bear at the outside against the bearing ring (3), such that these perform a reciprocating movement. A rolling body cage (7) is open between the two rolling bodies (5) of largest diameter, which rolling body cage loads the rolling bodies (5) into the tapering gap (4) between the bearing ring (3) and the shaft (2) and thereby ensures that the rolling bodies (5) revolve on the shaft (2) when the latter is driven.

Description

Description title

Eccentric bearing state of the art

The invention relates to an eccentric bearing with the features of the preamble of claim 1. The eccentric bearing according to the invention is provided in particular for an electro-hydraulic piston pump unit of a hydraulic brake system of a motor vehicle. Such pump units are used to generate a hydraulic brake pressure to a brake actuation in slip-controlled and / or power brake systems.

Known eccentric bearings have an eccentric shaft which is integrally or otherwise mounted rigidly and eccentrically on a motor shaft of an electric motor or on an output shaft of a transmission which is drivable with the electric motor. On the eccentric shaft, a rolling bearing with the eccentric shaft concentrically enclosing bearing ring and arranged with rolling elements, which are arranged in a gap between the eccentric shaft and the bearing ring around the shaft, but usually not necessarily equidistant. The rolling elements are usually rollers or needles, but it can also be other rolling elements, such as balls. The bearing ring can be considered as an outer ring, an inner ring may be present, for example, be pressed onto the eccentric shaft. However, no inner ring is necessary, the rolling elements can also roll directly on the eccentric shaft. On the outside of the bearing ring are one or more pump pistons of the pump piston unit with their front ends. The pump pistons are pressed, for example with springs from the outside in contact with the bearing ring.

In the case of a rotary drive, the eccentric shaft, due to its eccentricity, executes a movement on a circular path and thereby revolves around itself. Because of the movement of the eccentric shaft on the circular path, the bearing ring also moves on one or the same circular path and thereby drives the pump pistons abutting on it to the desired lifting movement in order to convey brake fluid or generally fluid by alternating suction and displacement, such as it is known from piston pumps. Because of his

Roller bearing, the bearing ring does not rotate with the eccentric shaft.

In electrohydraulic piston pump units for hydraulic brake systems of motor vehicles, the eccentric bearings convert a rotary motion of an electric motor or an output shaft of a transmission into a lifting movement for driving the pump pistons.

Disclosure of the invention

The eccentric bearing according to the invention with the features of claim 1 has a rotationally driven shaft on which a roller bearing is arranged with a bearing ring enclosing the shaft and arranged in a gap between the shaft and the bearing ring around the shaft rolling elements, wherein the rolling elements equidistant can be arranged, but not need. A Wälzkörperkäfig keeps the rolling elements in their distances from each other, wherein the distances of the rolling elements may be the same or different. In contrast to known eccentric bearings, the shaft of the eccentric bearing according to the invention is provided concentrically to its axis of rotation, although conceivable and is not excluded from the invention that the shaft is eccentric to its axis of rotation. Instead of or optionally in addition to an eccentricity of the shaft of the bearing ring is eccentric to the shaft and the rolling elements have different diameters according to a different gap width between the shaft and the bearing ring due to the eccentricity of the bearing ring to the shaft. The rolling elements have diameters which are as great as the width of the gap between the bearing ring and the shaft at the circumferential location at which the respective rolling element is located.

In a rotary drive of the shaft roll the rolling elements on the shaft and in the bearing ring and run around the shaft as it is known from bearings. In this case, the rolling elements with a large diameter press the bearing ring from the shaft and on the opposite side, where the rolling elements with a small Diameter, the bearing ring approaches the shaft. It runs, so to speak, the changing gap width together with the rolling elements to the rotationally driven shaft, ie the widest, the narrowest and any other gap width run around with the rolling elements to the shaft. The bearing ring moves on a circular path around the shaft with an eccentricity to the shaft. A rotational movement of the shaft is converted into a lifting movement of one or more outside of the bearing ring abutting pump piston. The rolling elements run around the shaft at a lower rotational speed than the rotational speed of the shaft, as well as the speed with which the bearing ring moves in the circular path decreases. The eccentric bearing according to the invention has a speed reduction, a rotational speed of the eccentricity of the bearing ring is slower than the rotational speed of the shaft with a non-rotatable bearing ring. The speed reduction has the advantage that a drive with higher speed is possible, which allows for the same power the use of a smaller and lighter electric motor.

Another advantage of the eccentric bearing according to the invention is its simple and inexpensive construction. The eccentric bearing according to the invention is provided in particular for the explained use in an electro-hydraulic piston pump unit for generating a brake pressure in a hydraulic brake system of a motor vehicle, where it converts the rotary motion of an electric motor into a stroke movement for driving pump piston. However, the invention is not limited to this use but is also directed to the eccentric bearing as such.

The dependent claims have advantageous refinements and developments of the invention specified in claim 1 to the subject.

Preferably, the Wälzkörperkäfig is resilient (claim 2), it acts on the rolling elements inwardly against the shaft, outwardly against the bearing ring and / or in the circumferential direction. Claim 4 provides that the Wälzkörperkäfig acts on the rolling elements in the direction of the narrowing gap between the shaft and the bearing ring. These embodiments of the invention have the

Advantage that even with play between the rolling elements and the shaft or the Bearing ring, the rolling elements are subjected to a bias against the shaft, the bearing ring or when exposed to the narrowing gap against both the shaft and against the bearing ring. Even if the bias voltage is low, this embodiment of the invention ensures that the rolling elements roll on the shaft and in the bearing ring and thereby circulate around the shaft like the planetary gears of a planetary gear when the shaft (or the bearing ring) is driven to rotate. The circulation of the rolling elements around the shaft ensures the desired movement of the bearing ring on the circular path around the shaft.

For resilient training, claim 5 provides that the Wälzkörperkäfig is open at a peripheral location. This embodiment of the Wälzkörperkäfigs is comparable to a locking ring such as a snap ring or a snap ring. The open at one point training of Wälzkörperkäfigs also simplifies the assembly of the eccentric bearing according to the invention. According to

Claim 6, the Wälzkörperkäfig between the two rolling elements with the largest diameters open and acts on the rolling elements in both circumferential directions in the direction of the narrowing gap between the shaft and the bearing ring. If the eccentric bearing has only one rolling element with the largest diameter, the rolling element cage is open between it and an adjacent rolling element.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described below with reference to a drawing

Embodiment explained in more detail. The single FIGURE shows an inventive eccentric bearing in front view.

Embodiment of the invention

The eccentric bearing 1 according to the invention shown in the drawing has a shaft 2 which is enclosed by a bearing ring 3. In a gap 4 between the bearing ring 3 and the shaft 2 rollers 5 are arranged as rolling elements around the shaft 2 around. The bearing ring 3 and the rollers 5 can possibly be considered together with the shaft 2 as rolling bearings. The shaft 2 is located with a not visible in the drawing because behind the plane Electric motor rotating about its axis 6, which is also its axis of rotation, driven. The shaft 2 has no eccentricity. For example, it may be the end of a motor shaft of the electric motor.

The bearing ring 3 is eccentric to the shaft 2, a width of the gap 4 between the bearing ring 3 and the shaft 2 changes in the circumferential direction. Starting from a largest gap width, which is the upper right in the drawing, the gap width decreases in both circumferential directions to a smallest gap width, which is opposite to the largest gap width, in the drawing so bottom left.

The rollers 5, which form the rolling elements, have different diameters corresponding to the different gap width. The diameters of the rollers 5 are each as large as the gap 4 between the bearing ring 3 and the shaft 2 is wide at the point at which the respective roller 5 is located.

In a rotary drive of the shaft 2 roll the rollers 5 on a circumference of the shaft 2 and thereby run at a lower rotational speed than the rotational speed of the shaft 2 to. Together with the two rollers 5 with the largest diameters runs the largest gap width of the gap 4 between the bearing ring 3 and the shaft 2 to. Likewise, the smallest gap width of the gap 4 between the bearing ring 3 and the shaft 2 with the two rollers 5 with the smallest diameters around the shaft 2 to. In other words, an eccentricity of the bearing ring 3 with respect to the shaft 2 in a rotary drive of the shaft 2 rotates about the shaft 2, wherein the rotational speed of the eccentricity is smaller than the rotational speed of the shaft 2, if the bearing ring 3 does not rotate. The bearing ring 3 moves in a circular path about the axis 6 of the shaft 2, which is also its axis of rotation, wherein a speed of the circular movement of the bearing ring 3 is smaller than the rotational speed of the shaft 2, so there is a speed reduction instead.

The rollers 5 are received in a rolling element cage 7, which holds them in their distance from each other. Between the two rollers 5 with the largest diameters of the rolling element cage 7 is open and designed resilient in this way, comparable to a locking ring, as it is known for example as a snap ring or as a snap ring in mechanical engineering. The rolling element cage 7 has a bias voltage, it acts on the two rollers 5 with the largest diameters in the circumferential direction away from each other as shown by the arrows 8. By its bias of the Wälzkörperkäfig 7 acts on the rollers 5 in both circumferential directions in the direction of the narrowing gap 4 between see the shaft 2 and the bearing ring 3. By its bias of the tensioned

Wälzkörperkäfig 7 against the shaft 2 and against the bearing ring 3 before, so that the rollers 5 abut the shaft 2 and the bearing ring 3 and roll with rotating drive the shaft 2 on the shaft 2 and the bearing ring 3 and at half the rotational speed as the shaft 2 rotate around the shaft 2. In addition, the resilient, open at one point training of Wälzkörperkäfigs 7 simplifies the assembly of the eccentric bearing first

The rollers 5 are rotatably received in rectangular recesses, so-called. Bags, the Wälzkörperkäfigs 7. Such rolling element cages 7 are known from Wälzla- like, they are also referred to as bearing cages or just as cages. In roller bearings, the roller bearing cages are also referred to as roller cages, ball bearings as ball cages.

On the outer side of the bearing ring 3, pump pistons 9 are in contact with the bearing rings 3 with their front ends. The pump pistons 9, of which only front ends are shown in the drawing, are arranged radially to the shaft 2 and are pressed by non-illustrated piston springs from the outside against the bearing ring 3. The pump piston 9 are axially displaceable in pump bores 10 of a pump housing 1 1, that is received radially displaceable to the shaft 2. The eccentric bearing 1 is located in a cylindrical eccentric 12 of the pump housing 1 1 between the two pump piston 9, which are arranged opposite each other in the embodiment, ie in a boxer arrangement. By rotating drive of the shaft 2, the bearing ring 3 moves, without rotating with the shaft 2, at a lower speed than the rotational speed of the shaft 2 on a circular path about the axis 6 and axis of rotation of the shaft 2. The circular motion of the bearing ring 3 drives the pump piston 9 to a lifting movement. The pump housing 1 1 is part of a so-called. Hydraulic block, in which except the pump piston 9 further, not shown hydraulic components such as solenoid valves of a slip control device for a hydraulic brake system a motor vehicle and arranged hydraulically interconnected. Such hydraulic blocks are known per se and will not be explained further here.

Claims

claims

1 . Eccentric bearing for converting a rotary movement into a lifting movement, with a rotatably drivable shaft (2), with a shaft (2) enclosing bearing ring (3), and with rolling elements (5) in a gap (4) between the shaft (2 ) and the bearing ring (3) are arranged around the shaft (2), characterized in that the bearing ring (3) is eccentric to the shaft (2) that the rolling elements (5) have different diameters corresponding to a different gap width between the shaft (3). 2) and the bearing ring (3), and that the eccentric bearing (1) has a Wälzkörperkäfig (7).

2. eccentric bearing according to claim 1, characterized in that the Wälzkörperkäfig (7) is resilient.

3. eccentric bearing according to claim 2, characterized in that the Wälzkörperkäfig (7) is resilient in the circumferential direction.

4. eccentric bearing according to claim 3, characterized in that the Wälzkörperkäfig (7), the rolling elements (5) resiliently in the direction of the narrowing gap (4) between the shaft (2) and the bearing ring (3) acted upon.

5. Eccentric bearing according to claim 2, characterized in that the Wälzkörperkäfig (7) is open at a circumferential location.

6. Eccentric bearing according to claim 5, characterized in that the Wälzkörperkäfig (7) between the rolling elements (5) with the largest diameters is open.