Monday, December 31, 2012

1992 BMW 325i Crankcase Position/RPM Sensor 1.0


Several EV sources offer rpm sensors that can be mounted on the Warp 11.  Some of the sensors provide a 2, 3, or 4 pulse output per motor revolution.  By contrast, the BMW rpm sensor provides 58 pulses per revolution.  It may be possible to mount the original vibration damper directly on the Warp 11 motor shaft.  This would provide the original 58 pulses per revolution which might then interface directly to the BMW instrument cluster and/or the ecu without the use of an adapter.  Additionally, the damper incorporates two pulley wheels.  One pulley can be removed, but the second is welded to the damper itself and it would be perfect for the future incorporation of belt driven accessories.


Picture DSC05255 showing original 58 tooth vibration damper.  The crankcase position/rpm sensor is at 11:00.  Removal of the plastic end caps on each pulley exposed the attachment bolts.  Picture was taken after the removal of the six hub bolts and the auxiliary second pulley.

 
Removing the vibration damper (also called by some the harmonic damper) did not disappoint in the challenge.  The primary difficulty was to immobilize the M50 camshaft  to prevent engine rotation while the 22 mm hex bolt was loosened.  Since the engine was on its side in the shop, the oil pan was removed to expose the cam shaft.  A piece of wood was inserted adjacent to the cam shaft to prevent its rotation but still, the bolt held fast. 
 
 
Picture DSC05263 showing the insertion of a wooden block to prevent rotation of the camshaft during the removal of the 22 mm retaining bolt. 

 
Subsequent use of an oxy-acetylene torch to heat the hex bolt and adjacent donut shaped washer to nearly red heat, resulted in the easy removal of the bolt.  It was necessary to remove some adjacent pulleys (bolts hiding behind the plastic end caps !!) before the damper would slide off the 32.0 mm OD cam shaft. 
 
 
 Picture DSC05262 showing the removal of the 22 mm retaining bolt with its adjacent "donut shaped" spacer/washer.
 
The primary pulley appears to be welded to the damper and six M8 x 18 bolts attach the outer pulley (D=122 mm) to the damper.  Only five bolts came out without protest, and the sixth sheared in half, so additional effort will be required to remove the remaining bolt threads.

To see an excellent exploded view diagram of the parts involved, go to realoem.com and in the search field "Part NR Application Search" enter part number 11231730311, followed by selecting "Details for E36", then, select the "Belt Drive-Vibration Damper" tab in the "E36 325i Sedan, M50, Manual" category.   From the diagram, replacement of hub part number 06 with a new hub whose ID is consistent with the Warp 11 motor shaft diameter, should allow the damper to directly mount to the Warp 11 motor.

The 3.93 kg vibration damper is a 60 tooth disk which has two teeth removed.  When rotating, the 58 remaining teeth pass within 1 mm of the crankshaft position sensor/rpm sensor (CPS).  The engine mounted CPS was damaged during attempted removal, so an EBay replacement was purchased from carpartswholesale for $24.25  .


Picture DSC05267 showing the mesial face (closest to the engine) of the vibration damper (note the sheared bolt at 4:00 !!)



Picture DSC05268 showing the distal face (closest to the radiator) with integral pulley.




Picture DSC05272 showing the side view of the 3.93 kg vibration damper.  The outer pulley has already been removed.  Using a lathe, it may be possible to thin the metal disk adjacent to the teeth to reduce the weight of the damper if desired. The integral attached pulley may allow the future incorporation of belt driven accessories.

Thursday, December 27, 2012

1992 BMW 325i Instrument Cluster 1.0

Picked up a spare BMW 325i Instrument Cluster including the three attached male plugs and 4 inch wire leads from a local salvage yard to learn more about how it can be interfaced to the EV.  The donor was from vin # BABF4319PEK09282 which according to Mitsuhiko’s BMW VIN Decoder (http://www.bmw-z1.com/VIN/VINdecode-e.cgi ) was a 1993/06 BMW 325is E36 M50 Coupe with automatic transmission.  To facilitate the testing, each of the cable wires were terminated into plastic terminal blocks (McMaster Carr part #  7618K618) that were bolted to acrylic and labeled with both wire color and function.

 
                                                                  Picture DSC05248
Showing the fully wired instrument cluster attached to terminal strips.
 
 
 
                                                                 
                                                                    Picture DSC05249
Showing the labelled terminals and the individual wires that originated from the three sockets on the back of the instrument cluster.  Wire color description on the top, and function on the bottom.


Study of the backside of the cluster and comparison with the wiring diagram printed in the Bentley BMW 3 Series Service Manual determined the following:

(1)  There are three plugs that connect the cluster to the wiring harness.  A white Siemens 26 pin part # B0126-S501 (described as CONN A in Bentley), a blue Siemens part # B1026-S502 26 pin plug (described as CONN B in Bentley), and a black AMP 12 pin part # 1-963003-2 BMW1383712 PBTP plug (described as CONN C in Bentley).
(2) Pin 3 of CONN B is the chassis ground
(3) Pin 2 of CONN A is wired to three 3 watt illumination bulbs that provide back lighting of the instrument cluster.

One of the bulbs was burned out and it was sourced at Patrick BMW dealership and replaced.  Note that the 3 watt glass bulbs used for back lighting (second from left in picture) actually plug into a green socket (far left).  The green plug assembly could be removed from the back of the instrument cluster after rotating a quarter turn.

 
                                                                 Picture DSC05239
Showing the two types of bulbs that can be replaced from behind the instrument cluster.  The larger 3 watt back lighting bulbs (left side) are two pieces, while the smaller bulbs on the right appear to be a single unit.

After connecting the negative terminal (ground) of the 12 volt battery to CONN B pin 3 and then a jumper from CONN A pin 2 to the positive of the 12 Volt battery, the back lighting of the instrument cluster was illuminated !!  Each of the indicator and warning bulbs will be tested later.

 
                                                                 Picture DSC05253
Showing the back lighted instrument cluster after connecting 12 volts to CONN A pin 2 and ground to CONN B pin 3.
 
The coding plug was not included with the instrument cluster as obtained from the salvage yard and consequently the original mileage and service status lines at the bottom of the cluster can not be illuminated.  

It is intended that the 1992 BMW 325i’s EV build will retain the original ECU and the CAN bus.  The speedometer appears to be actuated from a signal produced by the vehicle speed sensor located on the differential.  The ICE gas gauge signal was produced by a pair of variable resistors wired in series as an integral part of the floats in the original ICE gas tank.  Replacement of these variable resistors with a new circuit might simulate a measurement of residual battery pack capacity.  It may be possible to replace the engine/radiator temperature gauge sensor with a thermocouple or equivalent device whose temperature range and performance corresponds to the approved temperature range of the Warp 11.

The original ICE RPM gauge obtained its signal from the crank position sensor (CPS), also referred to in Bentley as the Front Harmonic Balancer, or the Vibration Damper.  (A good drawing can be downloaded from the following link from realoem.com  


Builder’s Note:  The web page located at realoem.com is a tremendous resource of both BMW exploded view diagrams and BMW part numbers. 

If the vibration sensor, its mounting hub, and the crankshaft position sensor are removed from the original M50 engine and the parts mounted at the commutator end of the Warp 11, it should be possible to directly activate the tachometer when the Warp 11 is rotating. 

It may not be possible to incorporate the MPG gauge at the bottom of the RPM readout, but it would be a great if it could provide a measurement of watts per mile or equivalent measurement of energy efficiency.
 
From study of the wiring diagrams in Bentley it was possible to print an excel file that was then cut out and attached to the underside of the acrylic mounting plastic.  The descriptions listed below will be edited and updated as more is learned about the wiring of the circuits.  Readers are very welcome to contribute any information that they are willing to share about different ways that the BMW instrument cluster can be rewired for EV application. 

Wire Color
 
Conn
Description
 
 
 
 
Brn/Org
 
 A24
 
Grn/Vio
 
 A23
 
Red/Yel
 
 A22
 
Wht/Blk
 
 A21
Eng Control Sys
Blk
 
 A20
Eng Control Sys
Yel
 
 A19
 
Brn/Vio
 
 A18
Brake Fluid Ind
Brn/Grn
 
 A17
Park Brake Ind
Gry
 
 A16
Check Eng Light
Vio
 
 A15
 
Blu/Blk
 
 A14
Supp Restraint Sys
Wht/Vio
 
 A12
Data Link Conn
Wht/Yel
 
 A11
Data Link Conn
Gry/Brn
 
 A5
Transmission
Blu/Grn
 
 A4
Left Turn Ind
Blu/Brn
 
 A3
Right Turn Ind
Gry/Red
 
 A2
Interior Lights (3)
White
 
 A1
High Beam Ind
Brn/Gry/Yel
 
 B23
 
Blu/Blk
 
 B22
 
Brn/Grn
 
 B19
Oil Ind
Brn/Vio
 
 B18
 
Brn/Yel
 
 B17
 
Vio/Yel
 
 B16
 
Wht/Grn
 
 B15
 
Blu/Vio/Yel
 
 B14
 
Gry/Blk/Yel
 
 B11
ABS Ind
Wht/Gry
 
 B10
 
Blk/Red
 
 B9
 
Yel/Brn
 
 B8
Front Fog Lt Ind
Blu
 
 B6
Start/Charging
Grn
 
 B5
Charge Ind
Grn/Blu
 
 B4
 
Brn
 
 B3
 Ground
Blk/Wht
 
 B2
 
Wht/Red
 
 B1
Exterior Lights Sys
Blu/Vio/Wht
 
 B24
 
Blu/Brn/Yel
 
 B26
 
Brn/Yel
 
 C1
 
Brn/Blk
 
 C3
Vehicle Ground
Brn/Red
 
 C4
Hazard Ind