DE102005021161A1 - Started ring gear and flywheel e.g. for engines with high numbers of revolution, has circular base, having teeth at edges which have material on their surface for allowing high surface hardness compared to core of circular base - Google Patents

Abstract

The starter ring gear has a circular base, having teeth at the edges. The teeth have a material on their surface for allowing a high surface hardness compared to the core of the circular base. Radially inside the circular surface of the starter ring gear an adjacent material of higher firmness is provided compared to the core of the circular base. The external teeth are hardened with the circular inner surface material.

Description

The The invention relates to a starter ring gear or one with such Starter sprocket provided flywheel.

Starter sprockets or flywheels are for example in the DE 37 45 090 C2 described and illustrated. Such starter sprockets are usually shrunk onto the flywheel and / or pressed, for which purpose the flywheel has a corresponding receiving shoulder, on which the radially inner boundary surface of the starter ring gear is received.

at the design of flywheels for engines At high speeds, the achievable burst speed is an important Expedition Criterion for both the flywheel itself as well for the starter ring gear.

The Bursting strength of a ring gear can be achieved by appropriate shaping of the starter ring gear, so for example by appropriate radial dimensioning to be influenced. In modern engine construction However, they are the ones for the individual components available provided space very tight, so that the starter ring gear not dimensioned arbitrarily large can be.

Of the present invention was based on the object, a starter ring gear to create that opposite the previously known a higher Ensures bursting strength, this bursting strength relative to the particular one used Material is to be considered. The starter ring gear according to the invention should continue in a particularly cost-effective manner be produced.

at a starter ring gear with an annular base, the on the outer circumference one Has formed toothing, wherein the toothing forming material at least on the surface a higher one Has hardness as the material forming at least the core of the annular body, This will be according to the invention achieved in that the at the radially inner, annular boundary surface of the Starter ring gear adjacent Ma material has a higher strength than that at least the core of the annular the body forming material.

By the embodiment of the invention Sprocket is guaranteed on the one hand, that the surface the teeth have sufficient hardness to a high To ensure lifespan and on the other hand, the annular one body has sufficient toughness, at least in the core area, that no break between the hardened Areas of gearing and this body occurs. Furthermore but is the higher Strength of the annular the body at least at its radially inner region the bursting strength substantially elevated.

Experiments with a ring gear have shown that by means of the invention, the bursting speed of about 14,000 ¹ / min can be increased to about 19,000 ¹ / min.

In Advantageously, the higher Strength at the radially inner portion of the starter ring gear through hardening or tempering be achieved.

Even though it be useful can, hardening the external toothing simultaneously with the hardening of the inner portion of the starter ring gear, it is for many use cases advantageous if the two hardening processes are separated from each other are, so take place one after another. It can be particularly useful when the teeth first hardened and only then the radially inner portion of the starter ring gear to a higher one Strength is brought. By using separate production steps can the desired Material properties in the area of the teeth and in the radially inner Area of the body independently be adjusted from each other. It may be appropriate if the radially inner region of the body of the starter ring gear despite a higher Strength also has a sufficiently high toughness to stress cracks to avoid. The separation of the aforementioned manufacturing steps has the advantage that the teeth are made in the usual way and hardened and tempered and the already existing manufacturing equipment can continue can be used.

The Radial depth of the radially inner portion of the starter ring gear hardened or remunerated Material can be attached to the existing, radial extension or Dimensioning of the starter ring gear to be adjusted. It should but always guaranteed be that between these, for example, by tempering or hardening brought to a higher strength, radially inner portions of the starter ring gear and the hardened gear portions an intermediate area with a higher one toughness or lower hardness remains.

Based of the figures, the invention is explained in more detail.

there shows:

1 a starter ring gear in view,

2 the detail "Z" according to 1 and

3 a section along the line III-III of 1 ,

The in 1 illustrated starter ring gear 1 has an annular base body 2 , which has a toothing at its radially outer periphery 3 has formed. This gearing 3 can be made by machining or else by material displacement or extrusion.

In the illustrated embodiment, the starter ring gear is made from an originally straight rack, which has been rolled into the appropriate shape. The circumferentially opposite end faces of the originally straight rod are via a weld, preferably via a butt weld 4 , connected with each other. The starter ring gear 1 However, it can also be made from a toothless rod, which is first formed into a ring. This ring can then be the gearing 3 be formed in the manner already mentioned.

The starter ring made of a hardenable steel 1 is in a conventional manner with a flywheel 5 , this in 3 partially and only schematically shown connected. For this purpose, the flywheel 5 a shoulder forming an annular surface 6 on which the starter ring gear is shrunk and / or pressed, so that the annular inner surface 7 on the shoulder 6 is seated with radial bias, and at least part of the starter torque can be transmitted through the thus formed, non-positive connection. If necessary, the circumference of the starter ring gear can be specified 1 considers a welded joint 7a can be provided, which may extend even over sections of this extent sector-shaped.

As a material for the production of the starter ring gear 1 For example, C35 or C45 or a chrome-nickel steel such. B. 42CrMoS4 be used.

How out 2 can be seen, in the illustrated embodiment, the teeth 3 forming teeth 3a fully tempered, where they can be hardened first, for example, and then tempered, whereby any existing stresses are at least partially degraded. Out 3 the course of the hardened zone can be seen, the transition between the hardened, hatched zone 8th and the radially inner, higher toughness zone 9 of the starter ring gear 1 is shown in idealized form. Actually, between the two zones 8th and 9 a transition area available.

Advantageously, the teeth 3a be inductively hardened, which can be done for example by means of appropriately designed hardening coils.

Although in the illustrated embodiment, the gearing 3 or the teeth forming these 3a are fully cured or tempered, it may also be useful for many applications, if the edge regions of the toothing 3 have a corresponding treatment, the hardness depth can be only a few tenths of a millimeter, for example, between 0.3 and 1 mm. If necessary, however, the hardness depth can be greater.

Due to the at least external, higher hardness of the teeth 3 the wear occurring during operation can be considerably reduced.

By the fate of a radially inner zone 9 Tough material ensures that a shatterproof connection between the teeth 3a and the annular body 2 given is.

How out 3 can be seen, has the starter ring gear 1 at its radially inner edge region another, higher strength zone having 10 , This zone 10 may also be tempered, in a manner similar to that associated with the teeth 3a was mentioned.

The radial depth 11 the annular zone 10 is dimensioned such that between this zone 10 and the annular zone 8th an annular area 12 remains, which has a much higher toughness than the zones 8th and 10 , The annular area 12 Thus, preferably it should not undergo hardening or only one which ensures sufficient toughness to break the teeth 3a to avoid.

For some applications, it may be appropriate that the axial side flanks of the area 12 have a higher strength over a small depth, for which purpose a hardened or tempered surface layer can be produced. Such a configuration may be particularly advantageous if, as already described, the toothing 3 or teeth 3a are not solid or fully cured, so that the teeth 3a even have at least a small core area, which has a certain toughness.

1

Starter gear

2

annular body

3

gearing

3a

teeth

4

welding

5

flywheel

6

shoulder

7

annular inner surface

7a

welded joint

8th

annular zone

9

annular zone

10

annular zone

11

radial depth

12

annular area

Claims (8)

Anlasserzahnkranz with an annular base body which has formed a toothing on the outer periphery, wherein the toothing material forming at least at the surface has a higher hardness than the at least the core of the annular body forming material, characterized in that to the radially inner, annular boundary surface of the starter ring gear adjacent material has a higher strength than the at least the core of the annular body forming material. Starter ring gear according to claim 1, characterized that's the external toothing forming material and the annular inner surface forming Material remunerated are. Starter ring gear according to claim 1, characterized that's the external toothing forming material and the annular inner surface forming Hardened material are. Starter ring gear according to one of the preceding claims, characterized characterized in that the starter ring gear at its radially inner Area inductively surface-hardened is. Starter ring gear according to at least one of the preceding Claims, characterized in that the starter ring gear at its radially inner area after curing is tempered. Starter ring gear according to one of the preceding claims, characterized characterized in that the hardness or depth of remuneration is 1 to 3 mm at the radially inner portion of the starter ring gear. Starter ring gear according to one of the preceding claims, characterized characterized in that between the outer teeth forming, hardened zones and the hardened, radially inner region of the starter ring gear with a material zone higher toughness remains. Flywheel with a mounted friction clutch for use in connection with a motor vehicle, characterized that the flywheel carries a starter ring gear, which after at least one the claims 1 to 7 is formed.