Control a diesel engine event using an external control system running LabVIEW

[Ian_Ren]

I am going to implement certain controls on a diesel engine. Basically, I would like to actuate several relays on an diesel engine at fixed cam angles. Signals from the cam sensor and crank sensor are available. 

At the initial concept verification phase, I plan to use an external system to control these relays and would like to use LabVIEW.

Can someone suggest how I should proceed and what is the most suitable NI hardware for this task?

Thanks.

Ian

[smercurio_fc]

You will need to provide far more details in order for someone to be able to even begin to suggest hardware, given that NI sells hundreds of products. For example:

• What kind of relays are these? AC or DC?
• What are the electrical specs?
• What do you mean by actuating relays "at fixed cam angles"?
• What kind of signals are the cam sensor and crank sensor? Are they voltages or current? AC, DC? What signal levels? If AC, what frequency?
• How fast do you need to be able to sample?
• What is your required response time?
• ...

Give me a minute, I might think of some more...

[mishkin]

Answering some of those questions would be a great start. Keep in mind some of the important factors when choosing a multifunction data acquisition devices are form factor (USB, PXI, PCI, etc), types of measurements you'll be doing, number of necessary channels and counters, triggering abilities and more.

I recommend looking at our DAQ tool that allows you to narrow down our products based on some of those criteria.

[LV_Pro]

A question I have regarding the relays is whether they are actual electromechanical relays or solid state ones. Depending on what you intend them to do, their response time may be a major factor. If you are looking at a cam angle sensor to determine when the relay is closing of opening understand that many (most) mechanical relays react in tens of milliseconds, either opening or closing, which would represent many degrees or cam rotation on a shaft rotating at, say 500 rpm.

[Ian_Ren]

Many thanks for the responses. Due to the nature of the development program, I am not able to disclose more details. The program is similar to controling the fuel injectors of a gasoline engine. I guess word "relay" has caused some confusion. What I like to control is a solenoid valve powered by 12V DC from the car battery.  So a "relay" is really an electronic stwich to turn the 12V DC on/off.  

 The following is the the answers

•  What kind of relays are these? AC or DC?

          Electronic switch to control a solenoid valve power by 12V DC 

• What are the electrical specs?

           Electronic switch to control a solenoid valve power by 12V DC 

• What do you mean by actuating relays "at fixed cam angles"?

          I would like to turn the electronic switch on at, say, 10 deg before TDC in the compression stroke.         

• What kind of signals are the cam sensor and crank sensor? Are they voltages or current? AC, DC? What signal levels? If AC, what frequency?

        Cam and Crank sensors are just unpowered mag pickups. The waveforms are like sine waves, the level is less than 10V, 

         and frequency less than 5kHz. 

• How fast do you need to be able to sample?

         I would like to control the solenoid valve to within a few degrees of the required crank angle (at 3000 rpm engine speed). 

• What is your required response time?

         I would like to control the solenoid valve to within a few degrees of the required crank angle. So at 3000rpm, it would be in

          the range of +/- 0.1~0.2ms.       

Hope this makes it a bit clearer.

Thanks.

Ian 

[prcatk]

Ian,

Take a look at the cRIO stuff and the equipment from the folks at Drivven. They have cRIO modules and code that is expressly designed to perform engine control. Getting data from typical engine sensors ( VR type) requires significant signal conditioning and getting typical FI injectors to fire requires high current ( not your typical DIO 24 ma) drivers. Some engine ( Hitachi for example) injectors require "pick and hold" drivers to avoid excess current draw from engine ECU.

Are you trying to "piggy back" the signals from an exisiting engine ECU? If so you are going to have to be careful to not impact the exisitng ECU by tapping the signals of interest.

HTH

Link to Drivven

http://www.drivven.com/index.htm

[Ian_Ren]

HTH

Thanks for your advice. I will take a look at the Drivven.

Since I cannot discuss exactely what I am doing, I use FI injector just as an example. The solenoid valve will be powered by a 12V DC car battery which has a lot of juice, the control is just for turning this 12V DC power on or off.

I plan to "Tee" the raw crank and cam sensor signals. I had some success doing it this way without affecting the existing engine performance before. Thanks for the caution.

Regards

Ian

[prcatk]

Ian,

You are still going to need a "driver" to activate the solinoid. I've found using a PVN012 ( 20v, Opto-isolated, 4.5A switching AC/DC ) with an NI DIO works REALLY well to control

a high-power ( relativly) unit. These are from International Rectifier and stocked by Newark Electronics ( www.newark.com). Several companies build drivers for automotive FI style injectors that are designed to connect typical micro-controllers to automotive sensrs and actuators, try Freescale and others.

Using a simple "wired-or" tee connection with typical engine sensors can be an issue becuase of ground loops, signal loading  and noise. Are these VR style sensors? Freescale ( ex-Motorola) as some circuits to help with this as well as some APP Notes on waveforms. For more technical information look into the stuff on the 'net on the Megasquirt DIY ECU ( be carefull searching for this as some not so savory sites will found).

HTH