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student_documentation:intro:lfm

LIQUID FLOWMETER

Prototype vehicles are not required to install a liquid flowmeter during the 2019 season. Flow Meter Installation Area with Fittings

Description

The Max P-Series of Flow Meters are positive displacement piston type units capable of great accuracy over a wide range of flow rates and fluid viscosities. The P001-Shell Eco-marathon-001 Liquid Flow Meter (LFM) will measure flows from 0.005 to 200 cc/min.

In a piston type flow meter, four pistons and cylinders are arranged in a radial fashion around a central crankshaft. Two fluid ports on the cylinder wall, a port at the top of the cylinder, and a grooved piston enable fluid entering the flow meter’s central cavity to be measured and pumped out by each piston in turn. The valving action for each cylinder is accomplished by the piston adjacent to it. The accuracy of a piston flow meter is dependent on close tolerances in the cylinder wall and piston. Max Machinery regularly holds tolerances as fine as 0.00005 inches in the production of these meters. The movement of the pistons is converted to a circular motion at the central crankshaft, which is coupled to a magnet in the flow meter. This motion is sensed by an external electronic transmitter, which converts flow into a pulse train further processing by the transmitter.

The latest generation of transmitters use modern sensor technology coupled with advanced signal processing to deliver high levels of performance and reliability. Hall sensors are used to detect the position of a driven magnet inside a Max Flow Meter. Changes in position are tracked by a microprocessor, which generates an output proportional to the flow rate. Advanced signal processing provides both fine angular resolution (0.36 degrees rotation) and rapid response (output updated every one millisecond).

Filtration: Clearances between the flow meter piston and cylinder wall are typically 0.0002” to 0.0004”. Any dirt present in the system can jam or damage the unit. A 7 micron filter (such as a Swagelok SS-4F-7 stainless steel unit) is required, although materials with very high viscosities may require a coarser filter.

Temperature: A temperature sensor has been integrated into the liquid flow meter to allow sample by sample flow correction.

Caution! Do not exceed a flow rate greater than 200 cc/min or permanent damage will occur and teams may be liable. 

Characteristics

Weight (LFM only) 900g (2lbs)
Dimensions (LFM only) Ø 57mm x 105mm tall (Ø 2.3” x 4.125” tall)
Assembled Dimensions Ø 57mm x 130mm tall x 206mm wide
(Ø 2.3” x 5.1” tall x 8.1” wide)
Flow Range 0.005 to 200 cc/min
Maximum Pressure 500 bar
Ambient Operating Temperature Range -40° to 80°C
Metered Liquid Temperature Range -40° to 90°C
Required Filtration 7 micron
Port Size SAE ¼”
Supply Voltage 5-26 Vdc
Supply Current 25-30 mA typical
Resolution 6000 pulses/cc

Drawings and Dimensions

Filter & Fittings

Installation before event

Prior to arrival at the event, teams should:

  • Locate an area to accommodate the Liquid Flow Meter (LFM) in a vertical position with the electrical connector at the top.
  • This location must be below the fuel injector and the fuel tank, preventing air from flowing through the LFM.
  • The LFM may be secured with cable ties or the two ¼” - 20 NC threaded holes on the bottom.
  • The fuel line (6 mm internal diameter) should be safely routed (away from hot exhaust and rotating parts/pinch points) to the pre-determined LFM location with one union and two tube adapters, as shown in Figure below, in place of the LFM.

Pre-Event Installation

Installation at the event

  1. Remove union from fuel line at location of desired flow meter location
  2. Connect fuel line from fuel tank to the inlet of the fuel filter of the flow meter
  3. Connect fuel line from the injector to flow meter outlet
  4. Open the fuel tank valve slowly to allow fuel to fill the lines all the way to the injector (opening fuel line at injector might be required)
  5. Reconnect the fuel line at the injector when most of the air is out of the system
  6. Turn on fuel pressure
  7. Tilt and shake the LFM gently in order to remove remaining air bubbles. (Shell Eco-marathon representatives will finally evacuate the fuel system at tech inspection to ensure all air is out of the fuel system)
  8. Mount the LFM to the frame with the 1 ¾” spaced ¼”x 20 bolts on the bottom, or zip tie it to the frame
  9. Check for leaks at all connections!
  10. Route cable to the predefined area agreed upon by the team and Shell Eco-marathon representatives.
  11. Plug LFM cable into the Sensor port on the OBC

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student_documentation/intro/lfm.txt · Last modified: 2019/04/02 02:19 by Christoph Zingg