CTI Mag: “Efficient Synchronizer Solution for (Dedicated) Hybrid Transmissions”

The targets of future regulations for automotive CO2 emissions require increased engineering efforts and innovative solutions from the OEMs and their suppliers. Automotive powertrains will have to be optimised to highest possible efficiency to play their part in the future. That includes a consequent reduction or power losses and weight of automotive gearboxes. However, the emission targets can hardly be achieved by efficiency improvements of the conventional powertrain only. The preferred technology to fulfil the requirements are electric vehicles especially hybrid electric vehicles in parallel, serial or torque split configuration. Hybrid powertrains in parallel configuration require special transmissions to combine the power of the combustion engine and the electrical motor. This could be conventional dual clutch or even automated manual transmission upgraded with an electrical motor or dedicated transmissions for hybrid powertrains. Synchronizer systems will still have their place inside the future transmission to provide fast gear changes for an economical operation of the combustion engine.

Those market challenges triggered Oerlikon Friction System to develop advanced and innovative synchronizer solutions in order to support our customers and partners to address the above-mentioned requirements.

The Segmented Synchronizer System S³ with the high performance Carbon friction lining EF®8000 is the ideal solution for performance and efficiency upgrades of existing conventional gearboxes. The S³ concept provides the same performance like multi-cone synchronizers with less components. By reducing the weight of the transmission as well as a significant reduction of drag losses, the S³ concept is the right answer for cost- and fuel saving transmissions now and in the future. The Segmented Synchronizer System can be easily integrated into existing manual (MT) or dual clutch transmissions (DCT) without major modifications

The main requirements to synchronizer systems for hybrid transmissions are a compact design as well as high performance and efficiency. A compact design especially in axial direction is required, because additional components like the electrical motor must be integrated into the existing space of a conventional powertrain. Oerlikon Friction Systems
gives the right answer to those requirements by presenting the new ESync sychronizer family, which is designed to save as much space as possible without any limitation to the function or comfort. ESync enables our customers and partners to develop the most efficient hybrid dual clutch (HDCT) and dedicated hybrid transmissions (DHT).

S³ – Segmented Synchronizer System
The advantage of the Segmented Synchronizer System is the reduction of weight and increase of efficiency by reducing the number of components and friction surfaces. The S³ is able to replace double cone and triple cone synchronizers consisting of three components and two or three friction surfaces by a two-piece single cone design without impact on performance.

The concept of a conventional synchronizer is limited by a conflict between shift quality and torque capacity. A small cone angle reduces the shift time by increasing the torque capacity, but could also negatively influence shift quality. A larger cone angle provides good shift quality, but reduces the torque capacity and therefore increases shift time and shift force. Higher torque requirements need to be realised by multiple cone synchronizers with the consequence of increasing costs, weight and reducing efficiency.

The Segmented Synchronizer System is separating the function “synchronizing” and “releasing” by using a split friction ring with two different cone angles; the concept allows a reduction of the friction cone angle below the physical limit of conventional synchronizers. During synchronization, the blocker ring embraces the split ring and the inner small cone angle of the friction ring is providing the synchronizer torque. After synchronization, the larger outer cone angle of the friction ring allows the blocker and the friction ring to separate easily for a comfortable gear engagement. The benefits of the segmented synchronizer system are obvious:

›› Reduced drag torque due to a reduced number of friction surfaces – up to 40 %
›› Less weight by reduced number of parts                                                   – up to 20 %
›› Space reduction in radial and axial direction                                              – up to 13 %
›› Cost saving                                                                                                           – up to 30 %

can be used as a drop-in solution for existing MT and DCT transmissions. The replacement of a multi-cone system by the Segmented Synchronizer System S³ requires minimal modifications only; no changes to the hub and sleeve are required. The innovative friction ring can be combined with conventional brass or steel blocker rings.

is a perfect system to upgrade existing transmission for higher efficiency, lower weight and reduced space.


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