3B Scientific Low Temperature Stirling Engine Kit, Assembly Kit User Manual

Page 6

The low-temperature Stirling motor demonstrates how a
Stirling motor operates as well as the principles of its
design.

1. Description, technical data

The low-temperature Stirling motor is set in motion even
by the heat of the human hand. It only requires a tem-
perature difference of 5°C between the ground and the
top plate. The main cylinder is made of precision glass.
The displacer cylinder and the flywheel are transparent
acrylic so that the motion of the main piston, the dis-
placer piston and the crank drive can all be seen clearly.
The crankshaft and connecting rods have miniature pre-
cision bearings to minimise friction. Due to the matt black
coating of the top plate, the Stirling motor can also be
operated using solar power.

Speed:

80 rpm approx. at

∆

T 10ºC

Flywheel:

110 mm Ø

Dimensions:

138 mm x 110 mm Ø

2. Assembly instructions

2.1 Finishing

•

All components with burred edges should have their
burrs filed off using a flat or triangular file.

•

File down the surfaces on any workpieces if desired.

2.2. Assembly
2.2.1. Making a permanent assembly

•

We recommend use of “UHU plus endfest 300”, “UHU
plus schnellfest” or similar 2-component epoxy resin
adhesive. In order to prevent damage to the coating
of the top plate, avoid any contact with solvents.
Owing to the differing expansion coefficients of the
materials, do not allow any of the components to
increase temperature during the hardening of the
adhesive. Aluminium will contract much more on
cooling than the glass cylinder, thus creating tension
in the glass leading to a decrease in the internal di-
ameter of the main cylinder or possibly even causing
it to break. Glueing together to make the connections
should generally be performed at a consistent tem-
perature of approximately 20°C.

1. Glue the main cylinder

to the bracket

at room

temperature, then glue it to the

top plate.

2. Fasten the bearings

inside the bearing socket

Force the ball race

onto the crankshaft

and

apply a thin adhesive film to three points on its outer
surface. Then push the ball race

into one of the

two recesses of the bearing socket

. Any surplus

adhesive should be removed with a cloth soaked in
white spirit. Always wipe towards the outside when

doing this to prevent adhesive penetrating into the
bearings. From the other side push another ball race

onto the crankshaft

and proceed as before. To

achieve best alignment of the two ball races

leave

the crankshaft

in the same position until the

adhesive has hardened.

3. Glue the insert

into its recess in the crank disc

Make sure that both surfaces being adhered are flush
together. There is a marking on the outer surface of
the insert

. Align this marking along the transverse

bore of the crank disc

4. Next, glue the crank shaft journal

into the bore of

the insert

5. Glue cylinder rods

into the bore of the displacer

rod

and the main piston

. No adhesive residue

whatever may remain on the running surfaces of the
cylinder rods

. Push the cylinder rods into the

relevant bores till about 2 mm protrudes and apply a
small amount of adhesive to the protruding end. Then
push the cylinder rod

into its correct position and

remove any surplus adhesive as above. Make sure
the cylinder rod

of the main piston

is glued so

that it is slightly recessed so that it does not damage
the running surface of the main cylinder

later on.

6. When glueing the displacer socket

into the bore

of the displacer

proceed as follows. Push the

displacer rod

into the main piston’s socket

then push the main piston

into the main cylinder

. Next, attach the displacer socket

to the dis-

placer rod

. Glue this into the bore of the displacer

and position the complete module on the under-

side of the displacer

so that the displacer

just

touches the top plate

. Leave these components

in this position until the adhesive has fully hardened
to ensure that the displacer

and top plate

remain parallel.

7. Finally glue the bearing socket

into the bore of

the bracket

2.2.2. Making a temporary assembly
1. Press the ball race

into the bore of the connecting

rods

and

. All the bearings are supplied with-

out lubricant. To ensure that the bearings

run

smoothly always use the supplied, semi-spherical
washers

in the assembly. The spherical side of the

washers

should face the ball bearing

2. Push the first washer

, the long connecting rod

, the second washer

and the face of the crank

onto the crankshaft journal

.The small mark-

ing on the edge of the crank face

should be to the

right of the crankshaft journal

as seen in the

diagram.

3. Push the first wide clamping disc

, the long con-

necting rod

and the second wide clamping disc

onto the cylinder rod

of the main piston

having lubricated it slightly first. The diameter of the