Originally Posted by Jeroen Whatever term you use to define something, it also comes with an understanding what is included and what not. According to your definition:
But then how far do you take it? Apparently the cruise control isn’t given your feedback.
So let’s explore the boundaries of what is and isn’t contained in a fuelling system. Hopefully that will show you why I look at a governor somewhat differently.
A few examples that all affect the running of an engine;
My Jaguar has a so called “Running Loss System”. Some other manufacturers might call it differently. In essence the venting/pressure of the fuel tank is controlled by means of various valves, lots of plumbing, so called EVPA canisters (i.e. charcoal filters). It’s actually a pretty complex bit of kit. And it’s directly hooked up to the fuel tank. Now on a petrol car it's a bit different then on a diesel. But still in both cases it can affect the running of an engine.
Is it part of the fuelling system?
We probably both agree that the fuel pump is part of the fuelling system. But what about the relais that controls that pump. And that relais is subsequently controlled by the ECU or similar.
Does the fuelling system end at the electrical connector on the fuel pomp?
What about an inertia switch. It’s main function is to stop the engine in case of a crash. Depends a bit per manufacturer, but usually it trips the fuel pump relay and or electrical supply and these days calls the emergency services.
So with the term fuelling system we need to determine what is part of it. Different parts, different functions. And of course, these days, parts on cars could have multiple functions affecting different systems. E.g. the inertia switch that could trip three different actions, stop fuel, stop electrical supply, call 911.
So I start clustering bits and pieces and I tend to look at it at what is often referred to as a horizontal layered model. In the Telecom world sometimes referred to as the Hamburger model. The various layers have distinct interfaces and way of interacting with one another. could be mechanical, pneumatically, electrically, digital etc.
So here goes:
Layer 1 is all the ‘hard’ physical bits, e.g. pipes, tubing, valves, pumps, injectors,
Layer 2 is all sensors and actuators. e.g. temperature, pressure, flow sensors etc
Layer 3 is all electrical systems. e.g. wiring loom, fuses, connectors, relays etc
Layer 4 is the control layer, e.g. the various ECU, PCM, TCM etc.
Depending on your preferences, complexity of the systems at hand you might see a few more layers. A pneumatic system could sit in layer 3 and or 4.
A governor is essentially a PID controller. However, a mechanical governor for me is just a self contained metal box with usually just a few (mechanical) inputs. That’s why I put it in layer 1. You could argue some of the bits of a mechanical governor are part of layer 2 and 4. To me that isn’t useful. I think overall it fits in well in layer 1. It also needs to sit right on top of the engine.
Simply put, a mechanical governor for me is a simple physical item, similar like a fuel pump, a fuel filter, separator.
An electronic governor could sit, physically, anywhere obviously. But it can be part of an “electronic” box having a multitude of in- and output for various systems and it interacts, usually electronically/digitally with multiple function and systems. E.g. the cruise control system.
Such a layered approach works well on other system as well. E.g. brake system, drivetrain etc.
But as I said before, at the end of the day I think it is down to semantics, custom or certain conventions. Whatever you prefer / find more logical / natural
Low battery voltage can create all sorts of minor issues up to major issues, such as not starting. Although they could be minor, in many cases they are quite a bit more than that. There are various threads on the forums with car owners posting a host of issues that were related to low voltage. To my earlier comment. It’s not just low voltage. The same sort of issues can pop up due to poor connection. As cars get older you will see, over time, connectors, fuses and such corrode. That creates higher resistance, which cause a voltage drop across that component, which mean lower voltage for the rest of the car. So you see similar problems. But battery voltage and charge state is very easy to check.
Many low voltage problems can be identified by using a proper OBD scanner. There are many codes for various low voltage conditions across many different components. Trouble shooting what causes that low voltage can be tricky sometimes.
The limp home or whatever it happens to be called on a particular car can be triggered by various low voltage situations, or not, or a whole host of different reasons. In my Jaguar the actual term shown on the display is Fail Safe Mode. And there is no way it gets you home. The car does less then a crawl in that state.
Jeroen |