QLA Heat Sink

Table of Contents generated with DocToc

• Introduction
• JHU custom built June 2016
  • Parts
  • Manufacturing
  • Results

Introduction

The dVRK controllers use a JHU designed Quad Linear Amps board (acronyms defined in FAQ). The linear amplifiers are all mounted against a large heat sink (square aluminum barre). This solution provides enough heat dissipation for both the MTMs and PSMs since these arms tend to require very little power (for most tasks, less than 0.5 A per board). For the ECM and the SUJs, passive cooling is not sufficient. The ECM arm is not as light as the PSMs and require a fair bit more power. The second joint itself can draw close to 0.5 A continuously.

The QLA boards have multiple 2 pins 12 V connectors that are powered when the motor power is turned on. We can use these to power a fan for active cooling.

JHU custom built June 2016

Parts

Parts to build 4 heat sinks with fans,

• Heat Sink: Digikey P/N ATS2192-ND http://www.digikey.com/short/3p1qw4, $19.20 (need 2, each is cut in half)
• Fan: Digikey P/N 259-1578-ND http://www.digikey.com/short/3p183v, $6.04 each (need 4)
• Connector: Digikey P/N A31017-ND Qty 10, $0.168 each

Manufacturing

Each heat sink was first cut in half to match the length of the existing heat sink. We then drilled 3 holes, matching the spacing on the existing heat sink. We also drilled 4 holes, diameter 2.5 mm to mount the 40 mm fan. To mount the fan, we used 3 mm screws, 20 mm long. The length matches the cumulated thickness of the fan and heatsink:

To provide enough clearance for all the screws, we had to mill the heat sink fins:

The screws used to mount the heat sink depend on the QLA revision:

• Rev 1.0, delivered mm/yyyy: imperial 4-40, 3/8 long
• Rev 2.0, delivered mm/yyyy: ??
• Rev 3.0, delivered mm/yyyy: ??
• Rev 4.0, delivered mm/yyyy: imperial 4-40, 3/8 long

With the fan:

Results

This was tested on the SUJ controller, dSIB rev 2.0.

Fan	Time	Temperature
off	0:00	29 C (room)
off	0:15	44 C
off	0:30	50 C
on	0:40	46 C
on	0:45	37 C
on	0:50	34 C

Without the fan the temperature seems stable around 50 C. With the fan, the temperature goes down to 34 C.