What would we do without them?
Wayne Gerdes -
CleanMPG - Oct. 12, 2012
At 110, we are not talking about speed either
As you are reading this article, think about all that resides around your current locale? Your chair, the monitor, a printer, carpeted floors and even a window or two more than likely.
They all have one thing in common. Without numbers, they would not exist.
While that point is obvious, imagine driving a car without a speedometer.
When we drive, we all pay attention to how fast we are going. Some more than others but I digress
In the automobiles, we simply look at the speedometer.
According to the historians over at Continental, the speedometer was born on October 7th, 1902. An engineer named Otto Schulze registered the eddy-current speedometer at the Imperial Patent Office in Berlin.
And it was not long before this new fangled invention spread across the global automotive industry.
Today, speedometers are just rev counters with some math thrown in. They reveal the number of revolutions of the wheel or the gear shaft as a distance per unit of time. Today the idea behind the speedometer is even more relevant than when it was first conceived given the motor car of 1902 had a top speed of just 20 mph andthat was the sports car variety
The speedometer as a necessity
Eelco Spoelder, head of the Instrumentation & Driver HMI business unit at Continental:
[quote]Humans can perceive positive or negative acceleration but are lousy at determining constant speeds. Anyone after driving on the highway for a lengthy period that has turned off into a 20 mph PSL zone instantly notices how difficult it is to gauge the speed properly.[quote]
People rely on aids to give them reliable information about speed. Rev counters or fuel-level displays, acoustic or optical parking assist, blind spot assist and radar systems help whenever the driver needs precise information, but can only make a rough estimate themselves. Yeah, those are all Continental manufactured parts and systems as a Tier I supplier to the worldwide automobile industry.
From eddy currents and stepper motors: That is how the needle moves
From the first eddy-current speedometers to the instruments of today, technology has made great progress. The most noteworthy is the development from the mechanical-electromagnetic function principle to mechatronic or purely electronic systems. In Otto Schulze's eddy-current speedometer, a flexible shaft transmits the number of revolutions of the wheel or gear shaft to the speedometer and sets a magnet in rotation there. This rotation generates eddy currents in a metal disk, which is located over the magnet and is penetrated by its magnetic field. The reaction between the magnetic field and the eddy currents creates a torque which moves the disk in one direction. In order for the instrument's indicator to show the correct speed value, a calibrated spring holds the disk against the torque of the magnetic field.
Today, rev counters and speedometers are based on electronics, from the sensors to the indicators. In most vehicles, the driving force behind the speedometer and rev counter needle is a stepper motor moving the speedometer needle by a minimal angle (step) or by a multiple thereof. The smaller the step length, the more precise the movement of the speedometer needle. Microcontrollers convert the signals from the speed sensor on the wheel into the necessary steps of the stepper motor.
The type of indication does not differ much from the first speedometers 110 years ago, in terms of the main aspects.
Even though the first fully digital LCD display appeared in 1986 in the Volkswagen Golf II GTI, drivers in the cockpits of most cars still look at a needle that moves on a round scale and indicates the speed or number of revs.
1986 VW Golfs all-digital instrument display. Too bad more cars even today do not have this much information!
Spoelder added:
Quote:
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"The fact that speedometers and rev counters are usually round is largely for ergonomic reasons. Round instruments can be read intuitively. The driver doesn't need to concentrate much, can focus their attention on the road and still obtains the most important information."
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That is why instruments such as the speedometer, the rev counter, the tank display and the most important warning lights are all kept together within the driver's direct field of vision (of around 30 degrees), usually in an instrument panel behind the steering wheel.
BMW HUD
Directly from military development, an automobiles instrument panel can be displayed via HUD or heads-up display, which shows driving-relevant information in the driver's direct field of vision, as if floating above the hood.
Displays such as the radio, internal temperature or control actuations are usually not displayed in the HUD but can be found in the drivers central instrument cluster display.
However, there is a trend towards more infotainment which is calling for newer strategies as the separation between driving-relevant information in the instrument panel and infotainment in the center console is becoming harder to achieve.
The more infotainment displayed in the center console, the greater the risk of visual distraction. To prevent this, Continental is investing in a concept that displays the most important information in the instrument panel, according to the situation. This is made possible by ever better display technologies and graphics processors. Higher end graphics processors today allow full-color fluid and delay-free animations to be displayed in the instrument panel.
Meaning todays full-color LCD displays can even perform the tasks of traditional analog instruments.
The entire instrument panel can and in many new automobiles today, consists of a single screen with a larger freely definable area to better show content to match a given situation.
2013 Ford C-MAX hybrid - SmartGauge with EcoGuide LCD display. The speedometer is still a Hardware needle with printed backing but to each side is the "good stuff"
In the title pic, would it be cool to have that copper or bronze speedometer mounted on your dash? Retro does not even come close to describing that
Linear Mode
