CN107923273B

CN107923273B - Camshaft adjuster

Info

Publication number: CN107923273B
Application number: CN201680051154.0A
Authority: CN
Inventors: 雷沙特·阿拉斯; 于尔根·韦伯
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2015-09-10
Filing date: 2016-09-02
Publication date: 2020-06-02
Anticipated expiration: 2036-09-02
Also published as: US10385740B2; CN107923273A; DE102016216667A1; WO2017041799A1; US20180298790A1

Abstract

The invention relates to an electrically operated camshaft adjuster, comprising an adjusting gear (5) having a drive wheel (2) with an external toothing (7) and a further annular part (11) screwed onto the drive wheel. The drive wheel (2) has an internal thread (8) into which a further annular part (11), in particular an external thread (10) of the drive ring gear, is screwed.

Description

Camshaft adjuster

Technical Field

The invention relates to a camshaft adjuster for a heat engine, comprising an adjusting gear.

Background

A generic camshaft adjuster is known, for example, from EP 1718846B 1. The camshaft adjuster can be electrically operated and has a three-shaft gear as the adjusting gear, i.e. a harmonic gear. The drive wheel of the camshaft adjuster is screwed by means of a retaining ring. As an alternative to the fastening method, riveting, welding or riveting is specified in EP 1718846B 1.

A further configuration of an electrically operable camshaft adjuster is known, for example, from DE 10248355 a 1. Here, a brushless dc motor having a permanent magnet rotor is provided as the electric drive device.

A combination of a camshaft adjuster and a balance shaft in a heat engine is known from US 5,327,859 a. A generic camshaft adjuster is known, for example, from WO 2006/074732 a 1. EP 0902169B 1 shows a further camshaft adjuster.

Disclosure of Invention

The object of the invention is to improve a camshaft adjuster for a heat engine, which has an electrically operable adjustment gear, in relation to the prior art described, in particular with regard to an advantageous design of the assembly technology.

According to the invention, this object is achieved by a camshaft adjuster having the features of the invention.

The camshaft adjuster comprises, in a known basic design, an adjusting gear having a drive wheel provided with an external toothing and a further annular component screwed onto the drive wheel. According to the invention, the drive wheel has an internal thread concentric with its axis of rotation, into which the external thread of the further annular component is screwed. The camshaft adjuster is preferably operated electrically, but can in principle also be operated in other ways, in particular hydraulically.

The further annular part which is screwed onto the drive wheel with external toothing is preferably designed as an integrated drive ring with internal toothing. The drive ring gear is used in particular as a component of a harmonic gear drive, i.e. a three-shaft drive, which is provided as a setting gear.

In contrast to the known solutions, the drive ring gear is screwed onto the drive wheel, in particular the sprocket, by means of a separate screw connection. This construction enables a particularly rapid and at the same time precise assembly. A front cover on the arrangement consisting of the drive wheel and the further annular part is not necessary. Mechanical stresses and axial deformations are significantly reduced compared to devices with multiple threaded connections. In addition to assembly, the machining steps on the drive wheel are also simplified, in particular because a plurality of threaded bores is not required. By eliminating separate threaded holes distributed over the circumference, the arrangement of the drive wheel and the further annular component is particularly less prone to the formation of cracks, for example at the screw connection points, wherein the drive wheel is particularly suitable for heat treatment methods, in particular induction hardening.

In an advantageous embodiment, the further annular component screwed into the drive wheel, in particular the drive toothed ring, has on its circumference an operating contour suitable for the operation of the tool, which operating contour extends radially beyond the circumferential surface of the drive wheel. In this case, the preferably cylindrical circumferential surface of the drive wheel is located radially inside the outer toothing of the drive wheel. Likewise, the operating profile designed on the further annular component is preferably arranged radially inside the external toothing of the drive wheel. The operating contour is therefore located between the cylindrical circumferential surface of the drive wheel and the external toothing, viewed in the radial direction (relative to the central axis of the drive wheel and of the further annular component, which axis is the same as the axis of rotation of the camshaft adjuster). The drive wheel can be provided for driving the camshaft by means of any traction means or for driving the camshaft by means of a toothed section, in particular by means of a spindle.

According to a preferred development, the further annular component, in particular the drive toothed ring, has a centering contour corresponding to the bore of the drive wheel. It is thereby possible to screw the further annular component to the drive wheel and to center the further annular component relative to the drive wheel in one step. The centering contour of the further annular component and of the drive wheel is preferably arranged axially between the flange of the further annular component and the external thread.

Preferably, there is at least one relative adjustment transmission center axis and thus a normal plane relative to the center axis of the drive wheel, which normal plane intersects the cylindrical circumferential surface of the drive wheel and the centering contour of the drive wheel. In particular, the entire camshaft adjuster is thereby arranged in a particularly space-saving manner in the axial direction of the camshaft.

In order to ensure a reliable threaded engagement, an additional securing member can be provided. As a result, even the high transfer torques that may occur during operation of the camshaft adjuster cannot loosen or loosen the threaded connection. For example, the thread can be crushed when the thread is tightened, whereby the threaded engagement is no longer disassemblable. Alternatively or additionally, the drive ring gear and the drive wheel can have end walls which bear axially against one another and have a friction-increasing surface structure or which provide an additional positive connection via the base body edge.

For a threaded connection, no separate screw is required, since the threaded engagement consists only of the component drive ring and the drive wheel. The drive wheel is preferably directly screwed to the drive ring gear. For this purpose, the drive wheel and the drive toothed ring are preferably designed as one piece.

To ensure a reliable threaded connection, multiple turns of thread are required in the threaded engagement. Preferably, at least four turns of the thread are provided.

The threaded engagement is preferably arranged on the side facing away from the camshaft with respect to the external toothing of the drive wheel. In this way, the assembly can be carried out in a simple manner on the end side, and the space and the working surface for the tool are sufficient. In one refinement, the drive wheel forms an axial stop for the drive ring gear.

Drawings

Embodiments of the invention are further explained below by means of the figures. The attached drawings are as follows:

figure 1 is a simplified cross-sectional view of an electrically operable camshaft adjuster,

fig. 2 is a perspective view of a drive wheel of the camshaft adjuster according to fig. 1.

Detailed Description

An electric camshaft adjuster for a heat engine (i.e. a diesel or petrol engine), which is designated as a whole by reference numeral 1, has a sprocket wheel as a drive wheel 2 and a driven wheel 3 concentric with the drive wheel 2, which driven wheel 3 is fixedly connected to a camshaft 4. During operation of the heat engine, the camshaft 4 rotates at half the speed of the crankshaft, not shown, of the heat engine, as long as the camshaft adjuster 1 is not operated. The camshaft adjuster 1 can be provided for adjusting the timing of an inlet valve or an exhaust valve of a heat engine. With regard to the basic function of the camshaft adjuster 1, reference is made to the prior art cited above. Due to the electric drive of the camshaft adjuster 1, the camshaft adjuster 1 can be adjusted not only during operation of the heat engine, but also before the heat engine is started.

Fig. 1 only shows a schematic illustration of the adjusting gear 5, i.e. a harmonic gear, which is designed as a three-shaft gear. The rotation of the shaft of the electric motor, not shown, is introduced into the adjusting gear 5 of the camshaft adjuster 1 via the oldham coupling 6. The oldham coupling 6 is part of an oldham coupling, that is to say an oldham coupling is a compensating coupling which allows a radial offset between the drive shaft and the driven shaft. As long as the shaft of the electric motor and thus the oldham coupling 6 rotate at the rotational speed of the camshaft 4, no phase adjustment takes place between the crankshaft, not shown, and the camshaft 4 of the heat engine. This phase adjustment takes place only when the shaft of the electric motor, which serves as the adjusting shaft of the camshaft adjuster 1, is rotated at a rotational speed which deviates from the rotational speed of the camshaft 4, wherein the adjusting gear 5 is designed as a high-reduction gear.

The overall annular drive wheel 2 has an external toothing 7, which external toothing 7 can drive the drive wheel 2 by means of a traction means, i.e. a chain. On the inner circumference of the drive wheel 2 (one after the other in the axial direction) a bore designed as a centering contour 9 and an internal thread 8 are provided. The centering contour 9 extends in this case over a region which is axially shorter than the internal thread 8.

The internal thread 8 corresponds to an external thread 10 of a further annular component 11, which is a drive toothed ring connected in a rotationally fixed manner to the drive wheel 2. The drive ring gear 11 has essentially the shape of a sleeve, wherein a flange 12, which is an integral component of the drive ring gear 11, is located on the end face of the drive ring gear 11 facing away from the camshaft 4. Fig. 1 only shows a schematic illustration of the arrangement of the driven part 13, which is composed of a plurality of parts, of the various transmission parts radially inside the drive ring gear 11. The parts of driven member 13 are interconnected by

pressing surfaces

14, 15.

For screwing the drive ring gear 11 into the drive wheel 2, an operating contour 16, for example a hexagonal contour, is provided on the flange 12 of the drive ring gear 11, which operating contour 16 makes it possible to screw the drive wheel 2 and the drive ring gear 11 together by means of a tool, not shown. At the same time, the centering profile 9 of the drive wheel 2, which is designed as a bore, together with the corresponding centering profile of the drive toothed ring 11 ensures a precise coaxial arrangement of the drive wheel 2 and the drive toothed ring 11. The drive wheel 2, shown as a sprocket wheel, is constructed in one piece and is induction hardened at least over a part of its surface.

The operating contour 16 of the drive ring gear 11 is arranged radially outside the cylindrical circumferential surface, designated 18, of the drive wheel 2 and radially inside the outer toothing 7 of the drive wheel 2. A normal plane relative to the rotational axis of the camshaft 4, which is marked a (i.e. the center axis of the adjusting gear mechanism 5), intersects both the operating contour 16 of the drive ring gear 11 and the oldham clutch 6, so that the oldham clutch is mounted in a space-saving manner, partially engaged in the adjusting gear mechanism 5.

A further plane parallel to said plane intersects the cylindrical circumferential surface 18 of the drive wheel 2 and the centering profile 9. A radial bearing 17 designed as a sliding bearing is provided in the region radially inside the external toothing 7 of the drive wheel 2, and the driven part 13 designed as a driven wheel is supported in the drive wheel 2 by means of this radial bearing 17.

Due to the overall compact design of the camshaft adjuster 1, undesirable torques are introduced into the adjusting gear 5 in the smallest possible range during operation of the camshaft adjuster 1. The internal thread 8 and the external thread 10 of the drive ring gear 11 interacting therewith are oriented in such a way that the threaded connection of the

components

2, 11 is tightened during operation of the heat engine, i.e. during driving of the camshaft 4.

List of reference numerals

1 camshaft adjuster

2 driving wheel

3 driven wheel

4 cam shaft

5 adjusting transmission device

6 crosshead shoe half coupling

7 external tooth part

8 internal thread of driving wheel

9 centering profile, hole of driving wheel

10 external thread of driving gear ring

11 further annular part, drive toothed ring

12 Flange

13 driven member

14 extrusion surface

15 extrusion surface

16 operating profile

17 radial bearing

18 cylindrical circumferential surface

Axis of rotation A

Claims

1. Camshaft adjuster, comprising an adjusting gear (5) having a drive wheel (2) provided with an external toothing (7) and a further annular component (11) screwed onto the drive wheel, characterized in that the drive wheel (2) has an internal thread (8) concentric to its axis of rotation, into which internal thread an external thread (10) of the further annular component (11) is screwed, the further annular component (11) being designed as a drive ring with internal toothing, the drive ring (11) being a component of a harmonic gear drive provided as the adjusting gear (5).

2. Camshaft adjuster according to claim 1, characterized in that the further annular part (11) has on its circumference an operating contour (16) suitable for tool operation, which radially exceeds a circumferential surface (18) of the drive wheel (2).

3. Camshaft adjuster according to claim 2, characterized in that the operating profile (16) is arranged radially inside an outer toothing (7) of the drive wheel (2).

4. Camshaft adjuster according to claim 1, characterized in that the further annular part (11) has a centering profile corresponding to the hole (9) of the drive wheel (2).

5. Camshaft adjuster according to claim 4, characterized in that the bore (9) forming the centering profile is arranged between the flange (12) of the drive ring gear (11) and the external thread (10).

6. Camshaft adjuster according to claim 5, characterized in that a normal plane to the central axis (A) of the adjusting gear (5) is present, which plane intersects the cylindrical circumferential surface (18) of the drive wheel (2) and the centering contour.

7. Camshaft adjuster according to one of claims 1 to 6, characterized in that the external thread (10) and the internal thread (8) are arranged on the side of the external toothing (7) facing away from the camshaft.

8. Camshaft adjuster according to one of claims 1 to 6, characterized in that the threaded engagement of the internal thread (8) and the external thread (10) is reinforced by an additional securing member.