EP3555492A1

EP3555492A1 - Gear arrangement having an overload clutch and an electric motor-drivable drive train

Info

Publication number: EP3555492A1
Application number: EP17816411.7A
Authority: EP
Inventors: Stefan Lenßen; Michael Metz
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2016-12-13
Filing date: 2017-11-23
Publication date: 2019-10-23
Also published as: WO2018108205A1; US20200003264A1; DE102016124126A1; CN110050136A; KR20190094361A

Abstract

The invention relates to a gear arrangement (1) for a drive train of a motor vehicle, the gear arrangement (1) comprising a drive shaft (2) and a gear (4) fitted onto the drive shaft (2), wherein a friction clutch (5), which disengages if a limit torque for transmission between the drive shaft (2) and the teeth (3) of the gear (4) is exceeded, is used at a position on the gear (4) located between the teeth (3) and the drive shaft (2). The invention also relates to a drive train for a motor vehicle having this gear arrangement (1).

Description

Gear arrangement with an overload clutch

The invention relates to a gear arrangement for a (preferably having an electric machine) drive train of a motor vehicle, such as a car, bus, truck or other commercial vehicle, with a drive shaft and a gear shaft mounted on the drive shaft. The invention also relates to a drive train, preferably a hybrid drive train, for a motor vehicle, with an electric machine see and coupled to the electric machine or coupled gear arrangement.

In purely internal combustion engine driven drive trains, numerous methods are already known to dampen torque peaks, which are introduced approximately by a combustion engine or by the switching behavior of the driver in the drive train. In this connection, DE 10 2015 200 846 A1 discloses a torque transmission device for a drive train, comprising an input part and an output part and a slip clutch arranged between the input part and the output part, wherein the slip clutch is formed from a press-and-press connection.

In hitherto increasingly used hybrid drive trains, however, there is the particular disadvantage that relatively high torque peaks can occur in the torque flow between the electric machine of the drive train and the tires of the motor vehicle, which can only be damped relatively poorly by the existing elements, such as the transmission , Damage to the electrical machine can be the result.

It is therefore the object of the present invention to overcome these disadvantages known from the prior art and, in particular, to provide a means which ensures improved protection for drive trains with electric machines. This is inventively achieved in that a slip clutch that opens when exceeding a between the drive shaft and a toothing of the gear to be transmitted limit torque is used at a point on the gear, which is located between the teeth and the drive shaft. Below this limit torque or until reaching this limit torque is the

Slip clutch preferably closed permanently / over the entire range of torque.

As a result, a particularly effective protective measure for the drive train is implemented. The high energy peaks caused by the electric machine, which can increase to more than 2 kJ in operation (compared to a pure internal combustion engine driven powertrain maximum of 500 J), are effectively cut off and no longer transmitted in the drive train. The slip clutch thus forms a reliable impact protection in the gear arrangement.

Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

Does the slip clutch on a shaft-hub connection or the slip clutch is even formed by a shaft-hub connection, wherein a shaft portion of the shaft-hub connection via a press fit on a hub portion of the shaft-hub connection is placed the slip clutch is designed to save space. In this regard, it is furthermore expedient if a cohesive connection layer is arranged between the shaft region and the hub region. As a result, a Press-Presslöt connection in the form of shaft-hub connection is particularly cleverly integrated into the gear assembly. In this regard, again it is useful if the tie layer is applied to the shaft area or hub area prior to assembly of the shaft-hub connection. Alternatively, it is also advantageous if the connecting layer has a (first) connecting part layer which (before the assembly of the Shaft-hub connection) is applied to the shaft portion, and / or a (second) connecting part layer, which is applied (before the assembly of the shaft-hub connection) on the hub region. Alternatively, it is again possible to form the connection layer even in the form of a sleeve and to arrange this sleeve (during the assembly of the shaft-hub connection) between the hub region and the shaft region. Thereby, it is possible to variably set a thickness of the connection layer.

If the bonding layer is made of a soft metal, i. If the bonding layer is a soft metal layer, it is particularly efficient.

If an axial securing device is provided which secures the shaft region relative to the hub region in the axial direction of the drive shaft, the permanent connection of the shaft-hub connection is ensured.

In this regard, it is also advantageous if the toothing is designed as a helical toothing, since then the axial securing device securely supports the axial forces coming about on the toothed wheel. If the slip clutch is located in the radial direction outside a diameter which is half as large as a pitch circle diameter of the toothing, particularly high torques can be implemented by the slip clutch. In order to generate less high torque through the slip clutch and thus trigger the slip clutch earlier, it is alternatively also expedient to lay the slip clutch in the radial direction within a diameter which is half as large as a pitch circle diameter of the toothing.

It is advantageous further when the slip clutch is arranged in the radial direction between the drive shaft and the gear. In this case, the slip clutch preferably sits between an outer peripheral surface of the drive shaft and an inner circumferential surface of the toothed wheel. As a result, the components of the gear arrangement are particularly simple. Furthermore, it is advantageous if the gear is formed in several parts and the slip clutch is arranged in the radial direction between a toothing having outer rim portion and a rotatably connected to the drive shaft inner portion of the gear. This results in a particularly variable positioning possibility of the slip clutch in the radial direction.

Is the slip clutch sealed to an environment of the gear and / or the drive shaft out, it is particularly effective in operation before the gear and the drive shaft surrounding lubricants, such as oil, protected. The oil can surround the gearwheel and the drive shaft in the form of oil mist, spray oil or even as oil sump. Thus, no oil or other lubricant creeps into the slip clutch.

In this context, it is again expedient if the slip clutch to a first axial side and / or a second axial side opposite the first axial side by means of a sealing ring, such as an O-ring or a Wel- lendichtringes, or a mechanical seal or a gap seal the environment is sealed. As a result, particularly effective sealing means are realized.

Furthermore, the invention relates to a (hybrid) drive train for a motor vehicle, comprising an electric machine and a tooth arrangement coupled or to be coupled to the electric machine according to at least one of the embodiments described above.

Preferably, the tooth arrangement is arranged in the drive train between the electric machine and an output shaft. The output shaft then preferably forms directly the drive shaft with. Alternatively, it is also advantageous if the tooth arrangement is arranged directly on an output shaft of the electric machine, in which case the output shaft directly forms the drive shaft and the gear further couples the electric machine to a transmission.

In other words, a gear-integrated overload clutch is thus implemented. This solves the problem of quenching high energy bursts. Erfindungsge- According to the present invention, a press-press-soldering composite is preferably implemented as a shaft-hub joint in which the press-press-soldering joint is interposed between a gear and a shaft (drive shaft). The press-press-solder connection can be placed close to the toothing of the toothed wheel to achieve a high limit torque at which the slip clutch slips or is placed close to the drive shaft to translate slippage of the slip clutch even at low torque levels. Preferably, the press-press-soldering connection is realized in a drive train between an electrical machine and an output shaft, for example directly on an output shaft of the electric machine and a gear wheel which connects the electric machine to the transmission. More preferably, a seal is reacted on the press-press-solder joint to seal the press-press-solder connection from the environment.

The invention will now be explained in more detail with reference to figures, in which context also different embodiments are described.

Show it:

Fig. 1 is a longitudinal sectional view of a gear arrangement according to the invention according to a first embodiment, wherein the gear arrangement a

2, a longitudinal sectional view of a gear arrangement according to the invention according to a second embodiment, wherein the slip clutch is integrated in a two-part gear,

Fig. 3 is a longitudinal sectional view of a gear arrangement according to the invention according to a third embodiment, wherein the slip clutch, similar to FIG. 1, in turn, is arranged between the drive shaft and the gear, is now sealed in addition to the environment by means of two seals designed as O-rings, and Fig. 4 is a longitudinal sectional view of the gear arrangement according to the invention according to a fourth embodiment, wherein the slip clutch, similar to FIG. 2, in turn, is integrated in a two-part gear, now additionally lent via a shaft seal and a gap seal is sealed to the environment.

The figures are merely schematic in nature and are for the sole purpose of understanding the invention. The same elements are given the same reference numerals. Also, the various features of the different embodiments can be combined freely with each other.

A gear arrangement 1 according to the invention can be seen particularly well in FIG. 1 in its basic structure. The gear arrangement 1 is preferably part of a transmission device / transmission, which is not shown here for clarity, and may therefore also be referred to alternatively as a transmission device. The gear arrangement 1 has a drive shaft 2 as well as a gear wheel 4 arranged non-rotatably on the drive shaft 2. The drive shaft 2 can in principle be designed as a transmission shaft, such as a transmission input shaft or a transmission output shaft, a transmission of a hyb- riden or purely electric drive train, but in this embodiment is already direct / stoffeinteiliger part of an output shaft / output shaft of an electric machine of the drive train. The gear arrangement 1 is preferably used in the torque flow between the electric machine and the transmission / gearbox of the drive train.

According to the invention, a slip clutch 5 is inserted at a point between a toothing 3 (in the form of an outer toothing) of the gear 4 and the drive shaft 2 so that it opens when exceeding a between the drive shaft 2 and the toothing 3 to be transmitted limit torque. The slip clutch 1 is thus designed as an overload clutch and opens when the limit torque is exceeded, which is predetermined by the nature of the slip clutch 1. Below this limit torque, the gear 4, as shown in Fig. 1, via the slip clutch 5 rotatably connected to the drive shaft 2. Thus, below or until reaching the limit torque, the drive shaft 2 is firmly connected by the closed slip clutch 5 with the gear 4. The slip clutch 5 is provided in the form of a shaft-hub connection 6. The drive shaft 2 directly forms a shaft portion 7 of the shaft-hub connection 6, while a hub portion 8 of the shaft-hub connection 6 is formed directly by the gear 4. The shaft-hub joint 6 is thus formed between an inner peripheral side 18 / inner peripheral surface (boss portion 8) of the gear 4 and an outer peripheral side 19 / outer peripheral surface (shaft portion 7) of the drive shaft 2. The shaft region 7 and the hub region 8 are so matched to each other in terms of tolerance that they are non-rotatably connected to one another via an interference fit. In addition, a connection layer 9 in the form of a soft metal layer is provided in the shaft-hub connection 6. This connection layer 9 constitutes a cohesive connection layer 9 and serves, in addition to the (tolerance-related) press fit of the shaft-hub connection 6, for the material connection of the shaft region 7 to the hub region 8. Thus, through the shaft-hub connection 6 Press soldering connection implemented.

In principle, the connection layer 9 can again be designed differently. On the one hand, the connecting layer 9 may consist exclusively of a single connecting layer, which is first attached to the gear 4 and, after assembly with the drive shaft 2, additionally connects the drive shaft 2 to the gear 4. Alternatively, however, the connection layer 9 may also be arranged exclusively on the drive shaft 2. In addition, the connecting layer 9 may in principle consist of a sleeve which is inserted between the two components. It is also possible to attach both a (first) connecting part layer to the shaft region 7 and a (second) connecting part layer to the hub region 8. The slip clutch 5 thus functions according to the press-press soldering connection described in DE 10 2015 200 846 A1, which is why the further embodiment of this press-press soldering connection is considered to be integrated herein. The slip clutch 5 therefore opens, on the one hand, as a function of the binding force converted by the press fit and also as a function of the material bonding force / adhesive force realized by the cohesive connection layer 9. These binding forces finally set the limit torque, at which it comes to an opening of the slip clutch 5, fixed.

As can also be clearly seen in FIGS. 1, the gearwheel 4 is always supported on a shoulder 20 on the drive shaft 2 to a first axial side 12.

Also, it is always implemented advantageous in the operation of the gear arrangement 1 according to the invention, that the shaft portion 7 and the hub portions 8 in the axial direction via an axial securing device, which is not shown here for clarity, movement / are verschiebegesichert. In this context, it is particularly preferred if the toothing 3 is formed as a helical toothing. Alternatively, the toothing 3 can be implemented as a straight toothing or other types of toothing.

Furthermore, it can be seen that the slipping clutch 5 in the first exemplary embodiment according to FIG. 1, when viewed in the radial direction, is within a diameter that is half as large as a pitch circle diameter of the gear teeth 3. As a result, this gear arrangement 1 according to FIG intended for applications that already want a relatively early opening of the slip clutch 5 at relatively low torque limits.

In connection with FIG. 2 it can be seen that the slip clutch 5, however, can also be arranged outside a diameter which is half as large as a pitch circle diameter of the toothing 3. The gear arrangement 1 of the second embodiment is basically constructed and functioning like that of the first embodiment. Therefore, only the differences between the exemplary embodiments will be discussed below. In order to further offset the slip clutch 5 radially outward in comparison to the embodiment of the first embodiment, and thus to achieve a higher limit torque, the gear 4 according to FIG. 2 divided into two. A first part is implemented as an outer rim portion 10 and has the teeth 3 directly on. An inner portion 1 1 of the gear 4 is in turn permanently mounted non-rotatably on the drive shaft 2 and disposed radially within the outer ring portion 10. In the radial direction between the two sections 10 and 1 1, the slip clutch 5 is integrated. The slip clutch 5 per se is implemented in accordance with the slip clutch 5 according to FIG. 1, the shaft region 7 of the shaft-hub connection 6 now being implemented through the inner section 11 / through the outer peripheral side 19 of the inner section 11 and the hub region 8 the shaft-hub connection 6 is implemented by the outer rim portion 10 / by the nenumfangsseite 18 of the inner portion 1 1.

In order to arrange the slip clutch 5 / the shaft-hub connection 6 to a desired diameter, in principle, thick-walled sleeves can be used. In principle, these sleeves can additionally be used in the shaft-hub connection 6 or at another location.

In connection with FIG. 3 it can also be seen that it is advantageous to seal the slip clutch 5 in addition to the surroundings of the gear 4 and the drive shaft 2. For this purpose, two seals 17 are used in FIG. 3 for a first axial side and for a second axial side of the gear 4, both of which are implemented as sealing rings 14, namely O-rings. O-rings are particularly advantageous in this context, since it does not occur very frequently during operation of the tooth arrangement 1 that the slip clutch 5 opens and thus the gear 4 rotates relative to the drive shaft 2. The further embodiment of the gear arrangement 1 of the third embodiment is constructed in principle as well as the functioning of the first embodiment.

Alternatively, as shown in connection with FIG. 4, however, it is also possible to seal the slip clutch 5, here with reference to the two-part gear 4, with differently designed seals 17 to the environment. To a first axial side 12 of the gear 4, a gap seal 16 is implemented, which simultaneously defines an axial stop between the two sections 10 and 1 1. To a second axia len page 13 of the gear 4 towards the slip clutch 5 is sealed by means of a shaft sealing tring 15 to the environment. The further embodiment of the gear arrangement 1 of the fourth embodiment is constructed in principle as well as the functioning of the second embodiment.

It should also be noted that, as an alternative to the seals 17 shown in FIGS. 3 and 4, the seals may be formed in other ways and other combinations of seals 14 may be realized. The individual seals 17 can be replaced by other sealing rings, such as O-rings or shaft seals, mechanical seals or gap seals.

In other words, according to the invention a PV-PLV (Press-Presslöt- connection) is implemented, which is constructed in the form of a shaft-hub connection 6, wherein the PV-PLV between a toothing 3 and a shaft 2 is arranged. Thus, in the present embodiments, an overload clutch is implemented as a press-press solder joint. In principle, the reason for the increase in the impact energies in the case of electrified or hybridized powertrains is the significantly higher inertia created by the electric motor (electric machine). The electric motor is very stiff (without damping elements) coupled to the transmission output shaft in these drive trains. For this reason, the inertia of a rotor of the electric motor (strongly translated due to the transmission) acts as a kind of hard stop in the event of a torque shock. Such a torque shock or impact can be initiated for example by a parking brake. Usually they do not rest only when the motor vehicle is at a standstill, but also at relatively low speeds. In an internal combustion engine drive, this shock is reduced by the softness in the drive train. This is very limited in the case of an electric or hybrid drive, so that an additional protective coupling is necessary, which protects the components in case of overload. In contrast to known protective clutches between internal combustion engine and transmission, the energy that must be dissipated from the overload clutch in the above-mentioned application of the electrified drive trains, significantly larger. Due to the high rigidity can significantly less energy in elasticities cached, so that the protective coupling energies over 500 joules must break down several times, without taking damage. This requirement is fulfilled by the PV-PLV, as proven in experiments. Results of a series of experiments in which the introduced energy was increased to over 2 kJ show that this 2 kJ is not the limit even for the geometry used. About geometrical adaptation of the slip clutch 5, the degradable energy can be varied. This is inventively implemented by the arrangement of the slip clutch 5 in the gear assembly 1. In this case, the PV-PLV can either be mounted as close as possible under the toothing 3 with a diameter greater than 50% of the pitch circle diameter (FIG. 2), if the slip torque should be as high as possible, or as close as possible to the shaft 2 with a diameter of less than 50%. the pitch circle diameter (Fig. 1), if the overload protection should trigger even at low torques. Under certain circumstances, it may be advantageous to use an additional thick-walled sleeve in order to be able to position the PV-PLV to the desired diameter.

The impact protection coupling (slip clutch 5) is preferably located in a transmission between electric motor and output shaft. For example, the clutch 5 may be located directly on the electric motor shaft and the gear 4, via which engages the electric motor in the vehicle transmission.

Depending on the exact installation location, the press-press solder joint is exposed to oil in the form of oil mist, splash oil or even immersion. In order to prevent the creep of oil or other lubricants in the PV-PLV, it is advantageous to seal these. In the simplest case, this is done by means of O-rings which seal the slip clutch on one or both sides (FIG. 3). Due to the relatively low lifetime over the number of impacts, in which a rotation of shaft 7 to hub 8 occurs, O-rings are sufficient as a sealing element. Of course, all other known ways of sealing rotating components (with or without relative movement), such as shaft seals 15, mechanical seals, gap seals 16, etc. possible. In Fig. 4 is shown by way of example for a protective coupling 5 near the toothing 3, as on the one side via a shaft seal 15 and on the second side is sealed by a gap (gap seal 16). The example in Fig. 4 is intended to show that any combinations of different sealing elements (seals 17) are possible, if this is advantageous for example for reasons of space.

In the figures shown has been dispensed with the representation of an axial lock against the migration of the PV-PLV. However, tests have shown that this is to be provided advantageously. For example, a helical toothing 3 is here called, which generates axial forces, which would lead to the migration of the gear 4 when slipping. But also other disturbances such as vibrations or uneven force application may favor an axial emigration. In the case mentioned, the axial securing is therefore present.

Reference numeral gear arrangement

drive shaft

gearing

gear

slip clutch

Shaft-hub-connection

waveband

hub area

link layer

Outer rim section

base portion

first page

second page

seal

Shaft seal

gap seals

poetry

Inner circumferential side

Outer peripheral side

Claims

claims

1 . Gear arrangement (1) for a drive train of a motor vehicle, comprising a drive shaft (2) and a gear (4) mounted on the drive shaft (2), characterized in that a slip clutch (5) which, when one between the drive shaft (2) is exceeded and a toothing (3) of the gear (4) opens to be transmitted limit torque is inserted at a point on the gear (4), which is located between the toothing (3) and the drive shaft (2).

2. gear arrangement (1) according to claim 1, characterized in that the

Slip clutch (5) has a shaft-hub connection (6) and a shaft portion (7) of the shaft-hub connection (6) via a press fit on a hub portion (8) of the shaft-hub connection (6) is placed.

3. gear arrangement (1) according to claim 2, characterized in that between the shaft region (7) and the hub region (8) a cohesive connection layer (9) is arranged.

4. gear arrangement (1) according to claim 2 or 3, characterized in that an axial securing device is provided which secures the shaft region (7) relative to the hub region (8) in the axial direction.

5. gear arrangement (1) according to one of claims 1 to 4, characterized in that the slip clutch (5) in the radial direction outside or within a diameter which is half as large as a pitch circle diameter of the toothing (3).

6. gear arrangement (1) according to one of claims 1 to 5, characterized in that the slip clutch (5) in the radial direction between the drive shaft (2) and the gear (4) is arranged.

7. gear arrangement (1) according to one of claims 1 to 5, characterized in that the gear (4) is formed in several parts and the slip Coupling (5) in the radial direction between a toothing (3) having outer ring portion (10) and one with the drive shaft (2) rotatably connected to the inner end portion (1 1) of the gear (4) is arranged.

8. gear arrangement (1) according to one of claims 1 to 7, characterized in that the slip clutch (5) is sealed to an environment of the gear (4) and / or the drive shaft (2) out.

9. gear arrangement (1) according to one of claims 1 to 8, characterized in that the slip clutch (5) to a first axial side (12) and / or one of the first axial side (12) opposite the second axial side (13) by means a sealing ring (14), such as an O-ring or a shaft seal (15), a mechanical seal or a gap seal (16) is sealed to the environment.

10. powertrain for a motor vehicle, with an electric machine and coupled to the electric machine or coupled gear arrangement (1) according to one of claims 1 to 9.