CN113669423A

CN113669423A - Belt tensioner

Info

Publication number: CN113669423A
Application number: CN202010401819.4A
Authority: CN
Inventors: 李勇
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2020-05-13
Filing date: 2020-05-13
Publication date: 2021-11-19

Abstract

The invention relates to a belt tensioner for a belt drive system, the belt tensioner comprising: a base element (4) for fixed connection with a drive and/or driven device in a belt drive system; a first tensioning arm (10) with a first tensioning wheel (14 a); a second tensioning arm (8) with a second tensioning wheel (14 b); and a spring element (11) which is tensioned in the circumferential direction between the first tensioning arm and the second tensioning arm, wherein the first tensioning arm and the second tensioning arm can be rotated relative to one another and relative to the base element, wherein the first tensioning arm, the second tensioning arm and the base element each have a substantially arc-shaped radial bearing, wherein the first tensioning arm and the second tensioning arm are each supported radially on the radial bearing of the base element by means of a respective radial bearing, wherein the force-bearing center planes of the spring element, of the first tensioning wheel, of the second tensioning wheel and of the respective radial bearings substantially coincide.

Description

Belt tensioner

Technical Field

The invention relates to the technical field of vehicles. In particular, the invention relates to a belt tensioner for a belt drive system.

Background

In hybrid vehicles, in particular micro-hybrid vehicles, it is often necessary to provide a starter generator which can start the internal combustion engine in the motor mode of operation and can generate a current for the vehicle electrical system and for charging the vehicle battery in the generator mode of operation. Such a starter generator may be connected to the crankshaft of the internal combustion engine via a belt drive system, thus constituting a belt-driven starter generator (BSG). The belt drive system is provided with a belt tensioner, which usually has two tensioning rollers that respectively tension the belt on different drive edges on both sides of the starter-generator pulley in order to provide a suitable tension when the drive edges are alternately used as tight or loose edges. There are a variety of belt tensioner designs currently on the market.

A belt tensioner comprising two tensioning arms which are fixed to the same tensioner unit and which tension the belt of a belt-driven starter generator on both sides is disclosed, for example, in patent application EP 2154394B 1. However, the tensioner unit cannot adjust its position, and thus both tensioning arms require a greater range of oscillation when the slack side and the tight side of the belt change with the switching of the starter generator operation mode. If the pivoting range of the tensioning arm is too large, the requirements placed on the assembly are even greater, in particular with regard to the strength and service life of the assembly. In addition, the belt tensioner is not provided with a decoupling function, and thus its application range is limited to a certain extent.

Another belt tensioner is disclosed, for example, in chinese patent document CN 104048007B. Belt tensioners of this type likewise have two tensioning arms, each with a tensioning pulley, between which a spring element is tensioned. However, the spring elements are located at a greater distance from the respective radial plane of the pulley, and therefore the spring force of the spring elements is at a greater axial distance from the plane in which the load carried by the pulley acts, and the balancing performance of the belt tensioner is less than ideal. This undesirable balance makes the parts susceptible to deformation and therefore places high demands on the strength of the various parts of the belt tensioner. At the same time, belt tensioner imbalance can result in uneven application of frictional forces to associated components, particularly friction components, and thus reduced life of the associated components.

Disclosure of Invention

The technical problem to be solved by the invention is therefore to provide a belt tensioner for a belt drive system which is improved in terms of functionality as well as service life.

The technical problem is solved by a belt tensioner, in particular for a belt drive system. The belt tensioner comprises a base element for fixed connection with a drive and/or a driven device in a belt drive system, a first tensioning arm with a first tensioning wheel, a second tensioning arm with a second tensioning wheel, and a spring element, wherein the spring element is tensioned circumferentially between the first tensioning arm and the second tensioning arm, wherein the first tensioning arm and the second tensioning arm are rotatable relative to each other and rotatable relative to the base element, respectively. According to an embodiment of the invention, the first tensioning arm, the second tensioning arm and the base element each have a substantially arc-shaped radial bearing, wherein the first tensioning arm and the second tensioning arm are each supported, in particular relatively slidably, by means of the respective radial bearing on the radial bearing of the base element in a radial manner, wherein the force-bearing center planes of the spring element, of the first tensioning wheel, of the second tensioning wheel and of the respective radial bearing substantially coincide.

The belt tensioner can in particular be designed as an endless arrangement which surrounds the output of the drive and/or output shaft. Preferably, the base element, the first tensioning arm and the second tensioning arm of the belt tensioner are each configured as an endless member. The first tensioning arm and the second tensioning arm can be rotated relative to each other about a common axis of rotation and can be rotated relative to the base element, respectively.

Within the scope of the present description, the terms "axial", "radial" and "circumferential" refer to the above-mentioned common axis of rotation, unless otherwise indicated.

The belt of the belt drive system can drive or be driven by a disk mounted in a rotationally fixed manner on the output of the drive and/or output shaft. In other words, the disk on the output and/or driven shaft of the drive and/or driven device can be configured as a pulley for a driving or driven wheel in a belt transmission.

In particular in a belt drive system for a hybrid vehicle, in particular a micro-hybrid vehicle, the drive and/or the output can be a starter generator. The output and/or the output shaft of the drive and/or output drive can be the motor shaft of the starter generator. The belt drive system can transmit power between a starter generator, a crankshaft of the internal combustion engine and an auxiliary device. Advantageously, the belt tensioner may be secured to the starter generator by the base element.

The base element, the first tensioning arm and the second tensioning arm each have a radial bearing. Advantageously, each radial bearing portion axially projects from a respective annular base body constituting the base element, the first tensioning arm and the second tensioning arm, respectively. When the belt tensioner is completely assembled, the radial bearing portions of the base member, the first tensioning arm and the second tensioning arm are substantially superposed in the radial direction and can slide in the circumferential direction relative to each other two by two.

In this case, the first tensioning arm and the second tensioning arm each advantageously have a fastening portion for the spring element. The two ends of the spring element can thus be mounted on the first tensioning arm and the second tensioning arm by means of respective fastening portions, respectively, whereby the spring element can be tensioned between the two tensioning arms.

In this case, the first tensioning arm and the second tensioning arm advantageously each have a shaft for mounting the tensioning wheel. The first tensioning wheel of the first tensioning arm and the second tensioning wheel of the second tensioning arm can be used in a belt drive system for tensioning different drive edges of a belt and can provide a tensioning force for the drive belt by means of the spring force of the spring element.

In this case, the force-bearing center plane of the spring element, the force-bearing center plane of the first tensioning wheel, the force-bearing center plane of the second tensioning wheel and the force-bearing center planes of the radial bearing portions substantially coincide, i.e. the spring element, the first tensioning wheel, the second tensioning wheel and the radial bearing portions have approximately the same axial position. The coinciding force-bearing center planes are the belt running planes in the belt drive system. In particular, the radial bearing sections of the base element and of the two tensioning arms, which are arranged one above the other, have approximately the same axial position as the fixing sections for the spring elements and the shaft sections for mounting the tensioning wheels of the two tensioning arms.

Thereby, on the one hand, a decoupling function of the belt tensioner can be achieved, so that the belt tensioner can be used for starter generators with a plurality of operating modes. On the other hand, the spring force of the spring member acts in the same plane as the load carried by the pulley and the belt tensioner has improved balance performance. In this case, the relevant parts of the belt tensioner are not variable, and the friction of the relevant parts can be more balanced, thereby extending the service life of the belt tensioner as a whole.

According to a preferred embodiment, a substantially arc-shaped sliding bearing, i.e. a first sliding bearing, is arranged between the first tensioning arm and the second tensioning arm. Particularly preferably, the first slide bearing is designed as a plastic slide bearing. Particularly preferably, the first plain bearing is configured as a sliding bearing with an L-shaped cross section. The first plain bearing can be arranged axially and radially between the first tensioning arm and the second tensioning arm. Radial damping and axial damping can thereby be produced during the movement of the first tensioning arm relative to the second tensioning arm, so that the dynamic behavior of the belt tensioner, in particular under operating conditions, can be increased.

According to a preferred embodiment, a plain bearing, i.e. a second plain bearing, is arranged axially between the second tensioning arm and the base element. The second slide bearing serves in particular as an axial slide bearing. Particularly preferably, the second slide bearing is designed as a plastic slide bearing. Preferably, the second plain bearing is configured as an annular disc-shaped sliding bearing which is arranged between the annular base bodies for forming the second tensioning arm and the base element. Axial damping can thereby be generated when the second tensioning arm moves relative to the base element, thereby improving the dynamic behavior of the belt tensioner, especially under operating conditions.

In this case, the second plain bearing is advantageously annular and has a section extending in the axial direction. This facilitates the positioning of the second plain bearing, while local contact of the second tensioning arm with the base element in the radial direction, in particular between metallic materials, can be effectively avoided.

According to a preferred embodiment, the belt tensioner further comprises an end cap fixedly connected to the first tensioning arm, wherein a third slide bearing is arranged axially between the end cap and the base element. The third slide bearing serves in particular as an axial slide bearing. Particularly preferably, the third slide bearing is designed as a plastic slide bearing. Preferably, the third plain bearing is configured as an annular disc-shaped plain bearing. Axial damping can thereby be produced when the base element is moved relative to the first tensioning arm or relative to the end cap, as a result of which the dynamic behavior of the belt tensioner, in particular under operating conditions, is increased.

In this case, the third plain bearing is advantageously annular and has a section extending in the axial direction. This facilitates the positioning of the third slide bearing, while local contact of the end cap with the base element and/or of the first tensioning arm with the base element in the radial direction, in particular between metallic materials, can be effectively avoided.

According to a preferred embodiment, a first radial slide bearing is arranged between the radial bearing of the first tensioning arm and the radial bearing of the base element, and a second radial slide bearing is arranged between the radial bearing of the second tensioning arm and the radial bearing of the base element. Particularly preferably, the radial plain bearings are each designed as plastic plain bearings. Preferably, both radial plain bearings match the shape of the radial bearing portion, i.e. are entirely arc-shaped. Radial damping can thereby be produced when the first tensioning arm moves relative to the base element and/or the second tensioning arm moves relative to the base element, thereby improving the dynamic behavior of the belt tensioner, in particular under operating conditions.

In this case, the first radial plain bearing and the second radial plain bearing are advantageously connected to one another by a radially extending section. In this case, the two radial plain bearings are designed in one piece and can be mounted easily as an integral fourth plain bearing, for example, by being slipped onto the free end of the radial bearing section of the base element.

In the specification, the numbers of the sliding bearings, for example, "first", "second", "third", and "fourth", are used only for distinguishing the respective sliding bearings, and do not indicate the relationship such as the order or importance of the sliding bearings.

According to a preferred embodiment, the first tensioning arm forms an arc-shaped receiving space, in which the second tensioning arm and the radial bearing of the base element are supported. The first tensioning arm in this case provides a radial bearing for supporting the second tensioning arm and the base element, respectively, via the curved receiving space, as a result of which a bearing of the base element, the first tensioning arm and the second tensioning arm, which can slide relative to one another, can be realized in a simple manner. In this case, the curved receiving space, which optionally comprises a plain bearing, can advantageously be closed by the annular base body of the base element or by the annular base body of the base element and the end cap together.

According to a preferred embodiment, the spring element is arranged radially outside the curved receiving space. This advantageously makes it possible to use larger spring elements and saves space for arranging two tensioning wheels in the same axial position.

The belt tensioner provided according to a preferred embodiment of the present invention can achieve a good decoupling function, and thus can be used for a belt-driven starter generator in a hybrid vehicle, particularly a micro-hybrid vehicle. At the same time, the spring force of the spring element of the belt tensioner and the load experienced by the pulley act in the plane of belt travel, the belt tensioner has improved balance performance and a consequent improved service life. Further, by providing a sliding bearing in the belt tensioner, axial damping and/or radial damping may be generated, thereby improving the dynamic performance of the belt tensioner.

Drawings

A preferred embodiment of the invention is schematically illustrated in the following with reference to the accompanying drawings. The attached drawings are as follows:

FIG. 1 is a schematic perspective view of a belt tensioner in accordance with a preferred embodiment;

FIG. 2 is an exploded view of the belt tensioner according to FIG. 1;

FIG. 3 is a partial cross-sectional view of the belt tensioner according to FIG. 1 taken in a radial direction; and

FIG. 4 is a partial cross-sectional view taken axially in section of the belt tensioner of FIG. 1.

Detailed Description

Fig. 1 and 2 show schematic perspective and exploded views, respectively, of a belt tensioner according to a preferred embodiment. The belt tensioner can be used, for example, in a belt drive system in a hybrid vehicle, particularly a micro-hybrid vehicle. The belt drive system can transmit power between the starter generator, the crankshaft of the internal combustion engine and the auxiliary devices by means of its belt.

In this embodiment, the belt tensioner is mounted on the starter generator. As can be seen in connection with fig. 1 and 2, the belt tensioner as a whole is configured in the shape of a ring, which may surround a motor shaft (not shown) of a starter generator. The belt tensioner comprises a base element 4, a first tensioning arm 10, a second tensioning arm 8 and a spring element 11. The base element 4, the first tensioning arm 10 and the second tensioning arm 8 of the belt tensioner are each configured as an endless member. The first tensioning arm 10 and the second tensioning arm 8 can be rotated relative to each other about a common axis of rotation and can be rotated relative to the base element 4, respectively.

The base element 4 is provided with lugs with bolt holes, which are distributed along the circumference of the base element 4 for mounting the belt tensioner on the starter-generator.

The first tensioning arm 10 and the second tensioning arm 8 have shaft portions for mounting the tensioning pulleys 14a, 14b, respectively. The first tension pulley 14a is attached to the shaft portion of the first tension arm 10 via a tension pulley bolt 15 and a dust cap 16. The second tension pulley 14b is attached to the shaft of the second tension arm 8 via a tension pulley bolt 15 and a dust cover 16. The spring element 11 is arc-shaped. The first tensioning arm 10 and the second tensioning arm 8 each have a fastening for a spring element 11. The spring element 11 is mounted at both ends on the fastening of the first tensioning arm 10 and the second tensioning arm 8 by means of a plastic sleeve 12 and a washer 13, respectively, so that the spring element 11 can be tensioned between the two tensioning

arms

10, 8. The first tensioning pulley 14a of the first tensioning arm 10 and the second tensioning pulley 14b of the second tensioning arm 8 can be used for tensioning different drive edges of a belt in a belt drive system, and the two tensioning

arms

10, 8 can be driven to rotate relative to one another, if necessary, by means of the spring force of the spring element 11 and provide a tensioning force to the respective drive edges of the belt by means of the tensioning pulleys.

Fig. 3 and 4 show a partial section through the belt tensioner according to fig. 1 in radial and axial section, respectively. As can be seen in connection with fig. 2 to 4, the base element 4, the first tensioning arm 10 and the second tensioning arm 8 each have a substantially arc-shaped radial bearing portion. The first tensioning arm 10 forms an arc-shaped receiving chamber, the inner wall of which forms a radial bearing. The second tensioning arm 8 and the radial bearing part of the base element 4 are relatively slidably radially supported in the arcuate receiving chamber.

The belt tensioner further comprises an end cap 1 fixedly connected to the first tensioning arm 10. The end cap 1 is designed as a ring with an L-shaped cross section, which is fixedly connected to the first tensioning arm 10 by means of an axially extending sleeve section, for example by means of a press fit, and which axially abuts against the annular base body of the base element 4 by means of a radially extending annular disk section, whereby the first tensioning arm 10 is axially supported on the annular base body of the base element 4. The annular base body of the base element 4 simultaneously also provides an axial bearing surface for the second tensioning arm 8.

The force-bearing center planes of the spring element 11, of the first tensioning wheel 14a, of the second tensioning wheel 14b and of the respective radial bearing section substantially coincide. The spring element 11 is arranged here radially outside the curved receiving space of the first tensioning arm 10. The spring force of the spring element 11 of the belt tensioner and the load experienced by the pulley act in the plane of belt travel, improving the balance of the belt tensioner and the service life.

The belt tensioner according to the present embodiment includes a plurality of plastic sliding bearings, i.e., a first sliding bearing 9, a second sliding bearing 7, a third sliding bearing 3, and a fourth sliding bearing 6.

Between the first tensioning arm 10 and the second tensioning arm 8 a substantially arc-shaped first slide bearing 9 is arranged. The first slide bearing 9 is configured as a sliding bearing with an L-shaped cross section. Radial damping and axial damping can thereby be produced when the first tensioning arm 10 is moved relative to the second tensioning arm 8.

A second slide bearing 7 is arranged axially between the second tensioning arm 8 and the base element 4. The second plain bearing 7 serves as an axial plain bearing and is configured as a sliding bearing of annular disk type, so that axial damping can be produced upon a relative movement of the second tensioning arm 8 and the base element 4. The second slide bearing 7 has a section which projects axially from the ring-shaped body, so that contact of metallic material between the second tensioning arm 8 and the base element 4 can be effectively avoided.

A third slide bearing 3 is arranged axially between the end cap 1 and the base element 4. The third slide bearing 3 serves here as an axial slide bearing and is designed as a sliding bearing in the form of an annular disk, so that axial damping can be produced when the base element 4 is moved relative to the first tensioning arm 10 or relative to the end cap 1. The third slide bearing 3 has a section projecting axially from the ring-shaped body, whereby contact of metallic material between the end cap 1 and the base element 4 can be effectively avoided.

The fourth slide bearing 6 is configured as an arc-shaped support with a U-shaped cross section. The radial bearing of the base element 4 projects into the U-shaped opening of the fourth plain bearing 6. A radial slide bearing is thereby formed between the radial bearing of the first tensioning arm 10 and the radial bearing of the base element 4, and a radial slide bearing is formed between the radial bearing of the second tensioning arm 8 and the radial bearing of the base element 4. Radial damping can thereby be produced when the first tensioning arm 10 moves relative to the base element 4 and/or the second tensioning arm 8 moves relative to the base element 4. Thus, the dynamic performance of the belt tensioner can be enhanced by the radial and/or axial damping created as the various components move relative to one another.

The arc-shaped receiving space formed by the first tensioning arm 10 can be closed by means of the annular base body of the base element 4 and the annular disk section of the end cap 1. Optionally, a sealing ring 2 is provided between the end cap 1 and the base element 4. Optionally, a sealing ring 5 is provided between the second tensioning arm 8 and the base element 4. Therefore, the arc-shaped accommodating cavity can be isolated from the outside, and the normal operation of each sliding bearing is ensured.

Although possible embodiments have been described by way of example in the above description, it should be understood that numerous embodiment variations exist, still by way of combination of all technical features and embodiments that are known and that are obvious to a person skilled in the art. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. From the foregoing description, one of ordinary skill in the art will more particularly provide a technical guide to convert at least one exemplary embodiment, wherein various changes may be made, particularly in matters of function and structure of the components described, without departing from the scope of the following claims.

List of reference numerals

1 end cap

2 sealing ring

3, a sliding bearing; third sliding bearing

4 base element

5 sealing ring

6, a sliding bearing; fourth sliding bearing

7 a sliding bearing; second sliding bearing

8 second tensioning arm

9 a sliding bearing; first sliding bearing

10 first tensioning arm

11 spring

12 a plastic sleeve;

13 gasket

14 tensioning wheel

15 tensioning wheel bolt

16 dust cover

Claims

1. A belt tensioner for a belt drive system, the belt tensioner comprising:

-a base element (4) for fixed connection with a driving and/or driven device in the belt drive system;

-a first tensioning arm (10) with a first tensioning wheel (14 a);

-a second tensioning arm (8) with a second tensioning wheel (14 b); and

-a spring element (11) which is tensioned in the circumferential direction between the first tensioning arm (10) and the second tensioning arm (8);

wherein the first tensioning arm (10) and the second tensioning arm (8) are rotatable relative to each other and rotatable relative to the base element (4), respectively,

characterized in that the first tensioning arm (10), the second tensioning arm (8) and the base element (4) each have a substantially arc-shaped radial bearing,

wherein the first tensioning arm (10) and the second tensioning arm (8) are each supported radially on a radial bearing of the base element (4) by means of a respective radial bearing,

wherein force-bearing center planes of the spring element (11), of the first tensioning wheel (14a), of the second tensioning wheel (14b) and of the respective radial bearing sections substantially coincide.

2. Belt tensioner according to claim 1, characterized in that a substantially arc-shaped sliding bearing (9) is provided between the first tensioning arm (10) and the second tensioning arm (8).

3. Belt tensioner according to claim 1, characterized in that a sliding bearing (7) is provided in axial direction between the second tensioning arm (8) and the base element (4).

4. A belt tensioner according to claim 3, characterised in that the sliding bearing (7) is annular and has an axially extending section.

5. Belt tensioner according to claim 1, characterized in that it further comprises an end cap (1) fixedly connected with the first tensioning arm (10), wherein a sliding bearing (3) is provided axially between the end cap (1) and the base element (4).

6. A belt tensioner according to claim 5, characterized in that the plain bearing (3) is annular and has an axially extending section.

7. Belt tensioner according to claim 1, characterized in that a first radial slide bearing is provided between the radial bearing of the first tensioning arm (10) and the radial bearing of the base element (4), and a second radial slide bearing is provided between the radial bearing of the second tensioning arm (8) and the radial bearing of the base element (4).

8. A belt tensioner according to claim 7, wherein said first radial slide bearing and said second radial slide bearing are interconnected by a radially extending segment.

9. Belt tensioner according to any of claims 1 to 8, characterized in that said first tensioning arm (10) forms an arc-shaped housing in which said second tensioning arm (8) and the radial bearing of said base element (4) are radially supported.

10. Belt tensioner according to claim 9, characterized in that the spring element (11) is arranged radially outside the arc-shaped housing.