Duality

Standard

Since being boisterous is a direct consequence of hollow knowledge, I’ll write about some cool tech I recently had a chance to look into. To keep things simple and clutter free, I have links to pre-requisite information and for reference and further reading. While working on nothing in the current project, I looked into how a dual clutch transmission works and how data is transmitted in between various subsystems in an automobile.

I’m a bottom feeder. I work nonce and talk much. I need appreciation and want to portray myself as a know-it-all. I enforce my perspective of things on others and get irked when they balk. I’m a sycophantic suck up and I’ll be that because my intelligence limits me to work on meaningful things. I use low cunning and honeyed language to escape work. I’m narcissistic and I cannot bear someone else outshining  me.

Having a keen interest in transmission systems or colloquially, gearbox, it was intriguing to understand how a dual clutch transmission (DCT) sends an upshift recommendation to the instrument cluster. From wikipedia: “A transmission is a machine in a power transmission system, which provides controlled application of the power.”. In a car (or vehicle), the internal combustion engine is the power unit and it provides, through the transmission system, power to the drive wheels. The transmission unit, for example, is designed to deliver more torque in lower gears and higher power in higher gears (gear ratios). From manual transmissions that have dominated road cars till now to the new DCTs, transmission systems have become more complex and more efficient.

You can read about various transmissions in the wiki link above, we will be concentrating on DCTs. As the name suggests, the transmission consists of two clutches cleverly mounted over each other. Quintessentially, it is two manual transmissions fused into one. The advantage lies in the fact that each sub unit has alternating set of gear trains and each sub unit has its own clutch (“Dual” clutch).  Refer to the diagram below. This setup, along with the required electronics, gives the driver an option of fully automatic mode where the gearbox ECU handles everything and also a manual mode where the driver is required to shift gears.

dual-clutch-transmission-13

I’m an over excited socially overactive low life. I talk about random disconnected things. I like to be the centre of attention and hence usually let my self esteem flood the drains. I’m entertaining, doubt that not! I have no knowledge of all things and all knowledge of no things. I have a limited perspective of things but I think that I have seen and done much. I’m a motor mouth and I care to give no thoughts behind my words.

I’m a pseudo philosophical wannabe. I talk about varied things hanging on the fringes of reality. I do so because I want people to think of me as a stoner without knowing that I’m being thought of as an idiot. But I pay it no heed because I have my own set of pseudo philosophical views conforming to the general dogma surrounding stoners and I have no imagination. I have a bad boy outlook and I think that makes me cool.

In my studies, I looked into how, in manual mode, the driver is notified of an upshift at the best possible moment. Looking a bit deeper into DCT, each clutch hosts a transmission shaft. The transmission shafts are concentric and each transmission shaft is connected to a separate gear train system. The gear train is arranged in a constant mesh with “odd” gears (1, 3, 5 ,7) on the inner shaft and “Even” gears (2, 4, 6 and reverse) on the outer shaft. The gear train transmits power from the engine, via the engaged gear, to the differential that drives the drive wheels.

The gears are engaged by shifting the gear selector. The selected gear is free to spin on the drive shaft. The gear selector is fixed with the drive shaft and hence will turn the drive shaft. When the selector is locked with the gear, it will spin at the same speed and hence driving the drive shaft. The gearbox ECU is intelligent enough to pre-select the next required gear. The setup is such that the next required gear will always lie on the other transmission shaft (DCT is a sequential transmission). Hence it only requires disengaging the current clutch and engaging the other. In the automatic mode, this whole operation is controlled by the gearbox ECU and manual mode, the actual changing of gears is left to the driver.

transmission-dual-clutch (1)

Arrows indicate power transmission.

In automotive electronics, communication between various subsystems is done predominantly using the CAN protocol. Each ECU processes a CAN packet whenever it receives or transmits data. What message a CAN packet will carry and the priority of each message is decided by the designer. Since it is a bus protocol and there are n-number of ECUs interacting with the bus simultaneously, CAN protocol has to decide which data packet will be transmitted on the bus. The protocol ensures that the data with the highest priority wins the bus.

I’m prone to flattery and will tell anyone, who is ready to listen, about things that I do. I like to convolute things and make an impression by giving grandiose solutions to petty problems. I over work, over think and over react. I like sycophantic suck ups because they feed my ego and  I surround myself with such. I make random useless dry jokes and laugh about it, out loud and expect others to do so.

The gearbox ECU assimilates the current driving conditions and predicts the best possible moment to upshift a gear. This message is transmitted from the gearbox ECU to the instrument cluster and the driver is notified visually or audibly about the same. In some applications, flooring the pedal (hard acceleration) sets the “kickdown” mode. The gearbox ECU downshifts to lower gears giving more acceleration and then upshifts again accordingly. DCT allows for lightening fast gear shifts and also hassle free driving while cruising in the automatic mode.

I’m a generic socially acceptable meatbag. I go to social gatherings and I talk shit to people. I talk to shit people too about shit agendas and other shit people. I enjoy having behind-the-back conversations and forming opinions. I form opinions based on other opinions and I’m steadfast on those opinions because I think they are my own opinions. I cannot imagine working more than I’m given to do. I’m old wave but I try to be new school. I’m working hard and getting by until the day I die.

PS: This article is not a tutorial or a study aid. This post is for infotainment purposes and the author takes no responsibility for the dearth of technical information.

Ninja.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s