Transmission and method for producing a transmission

Abstract

The invention relates to a transmission (1) having a plurality of gears, each of which has a synchronizer ring (2), at least one synchronization element (3) with shift teeth, and a movable sliding sleeve (4) for connecting the synchronization element (3) to the synchronizer ring (2). The friction coefficient between the sliding sleeve (4) and the synchronization element (3) is less than the friction coefficient between the sliding sleeve (4) and the synchronizer ring (2), wherein the shift teeth of the synchronization element (3) have a convex shape, and the convexity of the shift teeth of the synchronization element (3) ranges from 15 µm to 30 µm. The invention additionally relates to a method for producing a transmission (1).

Description

[0001] Gearbox and method for producing a gearbox

[0002] The invention relates to a transmission according to the preamble of claim 1, a vehicle according to the preamble of claim 3 and a method for producing a transmission according to the preamble of claim 5.

[0003] Transmissions require multiple gear ratios. Different gear ratios are selected by connecting different gears with shift elements. Sliding sleeves connect a synchronizer hub to a synchronizer ring, which is connected to a gear. Sliding sleeves sometimes move out of the engaged position.

[0004] It is known to achieve different contact angles through a special microstructure to achieve different friction coefficients between the sliding sleeve and the synchronizer hub on the one hand, and between the sliding sleeve and the synchronizer ring on the other, thus achieving a more robust system in which the sliding sleeve remains in the engaged position. The corresponding microstructure can be created, for example, by a coating.

[0005] DE 10 2011 114 055 A1 describes a synchronizing device for a transmission of a motor vehicle, wherein the synchronizing device has a synchronizer body, a sliding sleeve and a synchronizer ring, wherein in particular the synchronizer body has a radially aligned external toothing and in particular the sliding sleeve (shift sleeve) has a radially inwardly directed internal toothing that engages with the external toothing, wherein the synchronizer ring has a particularly radially inwardly directed locking toothing for engagement with the toothing of a switching wheel (gearwheel) and a conical area that can be brought into contact with the sliding sleeve, and wherein with the aid of the synchronizing device - during operation - a pre-synchronization also takes place.Pre-synchronization can be realized by the synchronizer ring being designed and / or constructed in such a way that pre-synchronization can be realized due to the design of the synchronizer ring, namely the synchronizer ring has at least one spring tongue for this purpose.

[0006] DE 10 2010 017 922 A1 describes a transmission with at least one shaft on which a guide sleeve having a first external toothing and at least one sliding sleeve having an internal toothing are arranged in a rotationally fixed manner, wherein the sliding sleeve is adjustable between a disengaged position, in which the internal toothing and a second external toothing on a clutch element are not operatively connected, and an engaged position in which the internal toothing meshes with the second external toothing. It is essential that the internal toothing and / or the first external toothing are / is designed such that in the engaged position there is only point-like contact between them. This can, in particular, prevent unintentional gear disengagement.

[0007] The invention is based on the object of providing a novel solution to prevent unintentional disengagement of a sliding sleeve from an engaged position.

[0008] The object is achieved according to the invention by a transmission having the features of claim 1, by a vehicle having the features of claim 3 and by a method for producing a transmission having the features of claim 5.

[0009] Advantageous embodiments of the invention are the subject of the subclaims.

[0010] A transmission is proposed comprising a plurality of gears with a respective synchronizer ring, as well as at least one synchronizer body with shift teeth and a movable sliding sleeve for connecting the synchronizer body to the synchronizer ring, wherein a friction coefficient between the sliding sleeve and the synchronizer body is smaller than a friction coefficient between the sliding sleeve and the synchronizer ring. According to the invention, the shift teeth of the synchronizer body are crowned.

[0011] According to the invention, the crowning of the switching teeth of the synchronizer body is in a range of 15 pm to 30 pm.

[0012] In one embodiment, the synchronizer ring has segmented teeth. According to one aspect of the present invention, a vehicle, for example a commercial vehicle, a bus, or a passenger car, with a transmission is proposed, wherein the transmission is configured as described above.

[0013] According to one aspect of the present invention, a method for manufacturing a transmission is proposed, comprising a plurality of gears with a respective synchronizer ring, as well as at least one synchronizer body with shift teeth and a movable sliding sleeve for connecting the synchronizer body to the synchronizer ring, wherein a lower coefficient of friction is set between the sliding sleeve and the synchronizer body than between the sliding sleeve and the synchronizer ring. According to the invention, the shift teeth of the synchronizer body are crowned to adjust the coefficient of friction.

[0014] According to the invention, the switching teeth of the synchronizer body are formed with a crowning in a range of 15 pm to 30 pm.

[0015] In one embodiment, the synchronizer ring is provided with segmented teeth.

[0016] The inventive solution provides a special microstructure of the shift teeth, which allows for different friction coefficients between the sliding sleeve and the synchronizer body on the one hand, and between the sliding sleeve and the synchronizer ring on the other. Different friction coefficients arise from more (crowned toothing on the synchronizer body) or less (non-crowned toothing on the synchronizer ring) oil in the tooth contact, or from higher forces between the sliding sleeve and synchronizer ring (smaller contact area due to segmented shift toothing on the synchronizer ring) compared to the connection between the sliding sleeve and the synchronizer body.

[0017] The solution according to the invention achieves different friction coefficients between the sliding sleeve and the synchronizer hub on the one hand, and between the sliding sleeve and the synchronizer ring on the other, without the need for a coating. Therefore, coating costs can be avoided.

[0018] Embodiments of the invention are explained in more detail below with reference to a drawing. In the drawings:

[0019] Fig. 1 is a schematic view of a gearbox with a sliding sleeve, a synchronizer body and two synchronizer rings,

[0020] Fig. 2 is a schematic view of the transmission, with the sliding sleeve engaged with one of the synchronizer rings,

[0021] Fig. 3 is a schematic view of a segmented toothing of a synchronizer ring.

[0022] Corresponding parts are provided with the same reference numerals in all figures.

[0023] Figure 1 is a schematic view of a transmission 1 viewed from a rotational axis of a drive shaft. The transmission 1 has a plurality of gears (not shown), in particular idler gears, which run on a drive shaft (not shown). The drive shaft can be driven by an electric motor. The gears each have a synchronizer ring 2. Furthermore, at least one synchronizer body 3 is provided, which is arranged between two synchronizer rings 2 on the drive shaft and rotates together with the drive shaft. By means of a movable sliding sleeve 4, the synchronizer body 3 can be selectively engaged with one or the other synchronizer ring 2 of one of the gears or disengaged from both synchronizer rings 2. The gears designed as idler gears can mesh with a respective further gear, wherein the further gears are arranged on a shaft parallel to the drive shaft, to which an output can be coupled.

[0024] To realize multiple gear ratios, the transmission 1 has different gears that can be connected by shifting elements, in particular sliding sleeves 4. The sliding sleeve 4 connects the synchronizer body 3 to a synchronizer ring 2, which is connected to a gear.

[0025] The sliding sleeve 4 has a toothing that meshes with a toothing of the synchronizer body 3 and optionally with a toothing of one or none of the synchronizer rings 2. Simulations have shown that a sliding sleeve 4 can be held in an engaged shift position by different friction coefficients between the toothing of the sliding sleeve 4 and the toothing of the synchronizer body 3, on the one hand, and the toothing of the sliding sleeve 4 and the toothing of the synchronizer ring 2, on the other.

[0026] A friction coefficient between the teeth of the sliding sleeve 4 and the teeth of the synchronizer body 3 that is smaller than the friction coefficient between the teeth of the sliding sleeve 4 and the teeth of the synchronizer ring 2 therefore leads to a lower tendency of the sliding sleeve 4 to unintentionally disengage from the switching position with one of the synchronizer rings 2.

[0027] To achieve different friction coefficients, the switching teeth of the synchronizer body 3 are or will be crowned. The crowned shape is shown significantly exaggerated in Figure 1 for illustrative purposes. For example, a crowning of 15 pm to 30 pm can be provided.

[0028] In Figure 1, the sliding sleeve 4 is only engaged with the synchronizer body 3, but not with any of the synchronizer rings 2.

[0029] Figure 2 is a schematic view of the transmission 1, wherein the sliding sleeve 4 has been displaced to engage with one of the synchronizer rings 2.

[0030] The crowning leads to more oil between the shift teeth of the sliding sleeve 4 and the synchronizer body 3 through capillary attraction or capillary action K and thus to a lower friction coefficient.

[0031] Additionally, segmented toothing of the synchronizer ring 2 can be provided. For this purpose, the tooth thickness of several teeth is suitably made somewhat smaller. For example, the tooth thickness can be at least 10 μm to 50 μm, and at most, these teeth can be omitted completely.

[0032] Figure 3 is a schematic view of the segmented toothing of a synchronizer ring

[0033] 2. Some, in particular a few, teeth 5.1 are thinner than the remaining teeth 5.2 of the toothing. This also creates a higher contact pressure on the teeth 5.2 that are in contact with the teeth of the sliding sleeve 4. The smallest possible change in tooth thickness also results in more oil being located between the teeth of the sliding sleeve 4 and the teeth of the synchronizer body 3 than between the teeth of the sliding sleeve 4 and the teeth of the synchronizer ring 2, thereby achieving different friction coefficients. In order to prevent too much oil from being lost from the area due to the segmentation, only a few teeth 5.1 are made thinner and are preferably not omitted completely.

Claims

Patent claims 1. A transmission (1) comprising a plurality of gears with a respective synchronizer ring (2), as well as at least one synchronizer body (3) with shift teeth and a displaceable sliding sleeve (4) for connecting the synchronizer body (3) to the synchronizer ring (2), wherein a coefficient of friction between the sliding sleeve (4) and the synchronizer body (3) is smaller than a coefficient of friction between the sliding sleeve (4) and the synchronizer ring (2), wherein the shift teeth of the synchronizer body (3) are crowned, wherein the crowning of the shift teeth of the synchronizer body (3) is in a range from 15 pm to 30 pm.

2. Gearbox (1) according to claim 1, characterized in that the synchronizer ring (2) has a segmented toothing.

3. Vehicle with a transmission (1), characterized in that the transmission (1) is designed according to one of the preceding claims.

4. Vehicle according to claim 3, characterized in that the vehicle is designed as a commercial vehicle.

5. Method for producing a transmission (1), comprising a plurality of gear wheels with a respective synchronizer ring (2), as well as at least one synchronizer body (3) with switching teeth and a displaceable sliding sleeve (4) for connecting the synchronizer body (3) to the synchronizer ring (2), wherein a lower friction coefficient is set between the sliding sleeve (4) and the synchronizer body (3) than between the sliding sleeve (4) and the synchronizer ring (2), wherein the switching teeth of the synchronizer body (3) are crowned to adjust the friction coefficient, wherein the switching teeth of the synchronizer body (3) are formed with a crowning in a range of 15 pm to 30 pm.

6. Method according to claim 5, characterized in that the synchronizer ring (2) is provided with segmented teeth.

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