Motorised Charging Port Flap Mechanism

The problem

Charging port flaps protect the inlet from dust and water and are operated many thousands of times. A motorised flap must open reliably, close tightly against a seal, clear the charging connector and fit in a shallow body pocket. Students learn to package a small mechanism, size an actuator and think about sealing and failure modes.

Objectives

• Package the flap, hinge and drive in a shallow body pocket around a charging inlet.
• Design a hinge or four-bar linkage with a geared motor and end-of-travel detection.
• Use a Motion study to find motor torque, opening time and clearance to the connector.
• Design a seal and drainage and plan a manual release.

What you need

Key concepts

Hinge versus four-bar

A simple hinge swings the flap out on an arc; a four-bar can move it outward and sideways to tuck it against the body, needing less clearance.

Required motor torque

The torque needed to lift the flap's weight, compress the seal and overcome friction, multiplied by a margin for cold and wear.

End-of-travel detection

Limit switches or current sensing tell the controller when the flap is fully open or closed, so the motor stops and faults can be detected.

Manual release

A mechanical way to open the flap if the motor fails, so the car can still be charged.

Step-by-step guide

1. 1

   Set requirements

   Define the inlet type envelope, for example a CCS2 inlet, the pocket depth available, opening angle, opening time under about 2 seconds, and sealing to keep water out of the pocket. Add a requirement for a manual release and for flap position feedback. Note an example operating temperature range so the drive works in cold and heat. Include the connector handle swept volume as it is inserted, not just the inlet face.

   Checkpoint: A requirements table with inlet envelope, pocket depth, angle, time, sealing and release needs.

2. 2

   Sketch concepts

   Sketch a simple top-hinged flap, a side-hinged flap and a four-bar flap that moves outward and tucks along the body. For each, check the swept volume against the connector and the user's hand. Choose a concept by scoring clearance, part count, seal pressure and appearance. Record the reasons. Include a sketch of how the user reaches the inlet with each flap open, and how a manual release would work for each concept.

   Checkpoint: A concept matrix with a chosen layout and swept-volume sketches.

3. 3

   Model the pocket and flap

   Model the body pocket around the inlet envelope as a moulded part with draft. Model the flap as a plastic moulding with an outer surface matching the body, a stiffening rib pattern inside and a hinge boss. Check draft with Draft Analysis. Choose a plastic such as PC/ABS from the material library and note it is an example choice. Keep wall thickness uniform so the moulding cools evenly.

   Checkpoint: Pocket and flap parts with adequate draft shown in Draft Analysis.

4. 4

   Model the linkage and drive

   Model the hinge arm or four-bar links, pins and a geared motor envelope from the datasheet. Add a gear or crank between motor and arm, with the ratio as a parameter. Place limit-switch envelopes at open and closed positions. Add a manual release cable or lever that disengages the drive. Keep links short and stiff so flap position is not lost through play, and leave space for a cable to the motor and switches.

   Checkpoint: A drive layout that fits within the pocket depth, with limit switches positioned at both end stops.

5. 5

   Assemble with mates

   Fix the pocket. Add concentric mates at pins, a gear mate if you model gears, and Angle Limit mates for open and closed positions. Check by dragging that the flap moves through its full travel. Run Interference Detection at open, mid and closed positions against the inlet envelope and a connector-handle envelope. Save the three check positions as named views or configurations so they can be reviewed later.

   Checkpoint: Flap moves through full travel without interference at any checked position.

6. 6

   Run the Motion study

   In a Motion Analysis study, add a rotary motor at the drive with a speed profile that opens the flap in the target time, turn on gravity and add a compression spring or contact to represent seal compression at closing. Plot motor torque and power against time. Repeat with the car parked on a slope by tilting gravity. Also run a closing case where the motor must compress the seal to its working squeeze.

   Checkpoint: A torque curve showing peak torque, with the worst case found across slope directions.

7. 7

   Select the motor

   Take peak torque from the study, add friction and a margin for cold-weather seal stiffness and wear, for example 2 times, and select a geared motor whose rated torque exceeds it at the needed speed. Check stall torque is not so high that a trapped finger is hurt; add current limiting to the requirements. Record the selected motor and ratio.

   Checkpoint: A motor and ratio whose rated torque exceeds the required torque with the stated margin.

8. 8

   Design the seal and drainage

   Add a gasket groove around the flap or pocket edge and model a gasket section. Check gasket compression at the closed position with section views. Add drainage holes at the bottom of the pocket so water entering during charging can escape. Consider an IP rating target for the pocket and state that it must be confirmed by test to IS/IEC 60529.

   Checkpoint: A section showing gasket compression within the gasket maker's recommended range and a drain path.

9. 9

   Check plastics and strength

   Check flap wall thickness for moulding and run SOLIDWORKS Plastics fill analysis if available, or use DFMXpress and Draft Analysis. Run a static study of the hinge boss under a user pushing on the open flap, with a stated force. Check stress against the plastic's yield with a suitable margin. Add a load case for wind pressure on the closed flap at an example highway speed.

   Checkpoint: Uniform wall thickness, a fill analysis or DFM check with no major issues, and hinge boss safety factor above target.

10. 10

    Drawings, renders and report

    Make drawings of the flap, links and pocket with key dimensions and tolerances. Render open and closed positions in Visualize. Write up concept choice, motion results, motor selection, sealing, strength and DFM checks. Recommend a life test of many open and close cycles with water spray and temperature cycling. Show seal squeeze, drain positions and the release cable route on a section view.

    Checkpoint: Drawings, renders and a report with a life-test plan.

Testing & validation

• Flap clears the inlet and connector envelopes through full travel.
• Motor rated torque exceeds peak required torque with margin.
• Gasket compression within recommended range.
• Hinge boss strength check meets target.

Expected results

A packaged motorised charging flap with a chosen linkage, motion-derived torque and opening time, a selected motor, a sealed pocket with drainage, a manual release and moulding-ready parts.

Take it further

• Add a pinch-detection strategy using motor current.
• Design a heated flap for icy conditions.
• Study flap aerodynamics and wind noise when closed.
• Compare a push-push mechanical latch with the motorised version.

Viva and review questions

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