Hydraulic Pump Motor Control Options

[iaindunn]

Hi All just joined.
If any one fancies a roll your own pump switch based on a 12f675 pic and a fet then I can post the code and schematics. The dead band can be easily programmed and the delay time to the pump switch off. The one I have in my excavator works great on 4 hydraulic channels

Iain UK

[doodlebug]

Hey Iain, Welcome aboard! Please share your info on the pump controler, New way's to do thing's are alway's appreciated here!
Later, Neil#2 aka doodlebug.

[egronvold]

Same reply as in another thread: As for the Leimbach system, it seems there's little difference in strength when it comes to the pump's speed. Here's a little test I did yesterday: http://www.youtube.com/watch?v=aqNTPp1g4pE

[iaindunn]

If you look at performance graphs for gear pumps the faster they rotate the greater volume they move which overcomes the internal leakage more and more.
However like most things there is a compromise and they will consume more and more power as they do this.

[iaindunn]

hi all
here is the asm code for a pump switch as used in my excavator for a couple of years. Works on a 12f675 pic. I'll try and post a link to video of it working soon.

;=============================================
; written by Iain Dunn
; 2 August 2010 revision release
; version 1.2 PCB EXPRESSPCB main revised3
; file saved as pumpswitch675.asm
; for 12f675
; int clock 4MHz

;==============================================
; Description,3 or 4 channel inputs for pump control
; via 1 fet 19N10.
; Input 4 not programmed yet
;
; |----||----|
; | 100n |
; 5v--|-------|----0V
; NC----|12f675 |----in2 GP0
;GP4pumpout----| |----in1 GP1
; GP3 in4----|-------|----in3 GP2
;
List P=12f675 ; define processor
#INCLUDE <p12f675.inc> ; processor specific definitions

;================================================= =================
;configuration
;no data protect
;no code protect
;no brown out reset
;no MCLR pin function
;power up timer disabled
;Watchdog timer enabled
;oscillator INTOSC with no CLKOUT

__config _CP_OFF & _CPD_OFF & _BODEN_OFF & _MCLRE_OFF & _WDT_ON & _PWRTE_ON & _INTRC_OSC_NOCLKOUT

errorlevel -302 ;suppress error 302

radix dec ;everything in decimal
;unless indicated



;========== constants========================================= ============

;GPIO,1 chan1 GPIO,3 chan 2 all rest outputs

#define INPUT_1 1
#define INPUT_2 0
#define INPUT_3 2
#define PUMPOUT GPIO,4
#define minpulse 80
#define lowon 140
#define highon 160
#define maxpulse 220
#define OFFDLAY 20 ; delays switching off pump
#define TisBits (1<<INPUT_1)|(1<<INPUT_2)|(1<<INPUT_3)
;========Notes==================================== ========================

;pulses must be larger than 0.8ms to be valid and less than 2.2ms
;The switching limits are
;1.55 ms upper off 1550us
;1.45 ms lower off 1450us


;==========Variables============================== =======================
cblock 0x20

CHAN_1 ; channel 1 width
CHAN_2 ; channel 2 width
CHAN_3 ; channel 3 width
ARM_PULSES ; stores arm pulse count
ARM_1 ; channel 1 arm pulse count
ARM_2 ; channel 2 arm pulse count
ARM_3 ; channel 3 arm pulse count
Dlay
Dlay_outer
Dlay_inner
OffCount ; delays pump switch off for 1/2 second

endc
;=========Declarations============================ =======================

org 0 ;first instruction to be executed

goto START

;========Initilizations=========================== =======================

INIT clrf GPIO ;clear all outputs for now
bsf STATUS, RP0 ; bank 1
call 3FFh ;call osc calibration
movwf OSCCAL
movlw b'1001010' ;WDT scale 1:4 gives around 72ms
movwf OPTION_REG ;before reset
movlw TisBits ;GPIO 2,3,5 input GPIO,0,1,4 output
movwf TRISIO
clrf ANSEL
bcf STATUS, RP0 ;bank 0
movlw b'00000111' ;turn off comparator
movwf CMCON ;digital i/o
clrf T1CON ;turn off timer 1
clrf ADCON0


return

;========== Start of main outer loop of program ===============================

START call INIT
clrf GPIO
clrf CHAN_1 ;
clrf CHAN_2
clrf CHAN_3
movlw OFFDLAY
movwf OffCount
movlw 50
movwf ARM_PULSES
clrwdt
;========== wait for 25 valid pulses to arm =====================

ARMING
clrf ARM_1
clrf ARM_2
clrf ARM_3
btfss GPIO,INPUT_1
goto $-1


ARMLOOP_1 incf ARM_1,f
btfss GPIO,INPUT_1
b ARM2
nop
b $+1
b $+1
b ARMLOOP_1

ARM2 btfss GPIO,INPUT_2
goto $-1

ARMLOOP_2 incf ARM_2,f
btfss GPIO,INPUT_2
b ARM3
nop
b $+1
b $+1
b ARMLOOP_2


ARM3 btfss GPIO,INPUT_3
goto $-1

ARMLOOP_3 incf ARM_3,f
btfss GPIO,INPUT_3
b PULSE_1
nop
b $+1
b $+1
b ARMLOOP_3


PULSE_1 movlw lowon
subwf ARM_1,w ; ARM_1-lowon(148)
bnc ARMING
movlw highon
subwf ARM_1,w ; ARM_1-highon(152)
bc ARMING


PULSE_2 movlw lowon
subwf ARM_2,w ; ARM_2-lowon(148)
bnc ARMING
movlw highon
subwf ARM_2,w ; ARM_2-highon(152)
bc ARMING


PULSE_3 movlw lowon
subwf ARM_3,w ; ARM_3-lowon(148)
bnc ARMING
movlw highon
subwf ARM_3,w ; ARM_3-highon(152)
bc ARMING



VALID_NEUTRAL
clrwdt
decfsz ARM_PULSES,f
goto ARMING

;========= now armed beep from both motors ==========================================
movlw 10
movwf Dlay_outer
clrf Dlay_inner

PWM_LOOP clrwdt
bsf PUMPOUT
movlw 10
movwf Dlay
decfsz Dlay,f
goto $-1
clrf GPIO
movlw 100
movwf Dlay
decfsz Dlay,f
goto $-1
decfsz Dlay_inner,f
goto PWM_LOOP
decfsz Dlay_outer,f
goto PWM_LOOP
clrf GPIO ;turn motors off

;========= Wait for channel pulses to start =========================================




RCIN1 clrf CHAN_1
btfss GPIO,INPUT_1
b $-1
LOOP_1 incf CHAN_1,f
btfss GPIO,INPUT_1
b RCIN2
nop
b $+1
b $+1
b LOOP_1



RCIN2 clrf CHAN_2
btfss GPIO,INPUT_2
b $-1
LOOP_2 incf CHAN_2,f
btfss GPIO,INPUT_2
b RCIN3
nop
b $+1
b $+1
b LOOP_2

RCIN3 clrf CHAN_3
btfss GPIO,INPUT_3
b $-1
LOOP_3 incf CHAN_3,f
btfss GPIO,INPUT_3
b PROCESS_IN_1
nop
b $+1
b $+1
b LOOP_3

;==========process the channel timings ====================================

PROCESS_IN_1
clrwdt
movlw minpulse
subwf CHAN_1,w ; CHAN_1-minpulse(80)
bnc PROCESS_IN_2
movlw maxpulse
subwf CHAN_1,w ; CHAN_1-maxpulse(220)
bc PROCESS_IN_2
movlw lowon
subwf CHAN_1,w ; CHAN_1-lowon(145)
bnc PUMP_ON
movlw highon
subwf CHAN_1,w ; CHAN_1-highon(155)
bc PUMP_ON

PROCESS_IN_2

movlw minpulse
subwf CHAN_2,w ; CHAN_2-minpulse(80)
bnc PROCESS_IN_3
movlw maxpulse
subwf CHAN_2,w ; CHAN_2-maxpulse(220)
bc PROCESS_IN_3
movlw lowon
subwf CHAN_2,w ; CHAN_2-lowon(145)
bnc PUMP_ON
movlw highon
subwf CHAN_2,w ; CHAN_2-highon(155)
bc PUMP_ON
PROCESS_IN_3

movlw minpulse
subwf CHAN_3,w ; CHAN_3-minpulse(80)
bnc RCIN1
movlw maxpulse
subwf CHAN_3,w ; CHAN_3-maxpulse(220)
bc RCIN1
movlw lowon
subwf CHAN_3,w ; CHAN_3-lowon(145)
bnc PUMP_ON
movlw highon
subwf CHAN_3,w ; CHAN_3-highon(155)
bc PUMP_ON


PUMP_OFF
decfsz OffCount,f
b RCIN1
bcf PUMPOUT
movlw OFFDLAY
movwf OffCount
b RCIN1

PUMP_ON bsf PUMPOUT
movlw OFFDLAY
movwf OffCount
b RCIN1

;============End programme ================================================== ========

return
END

[iaindunn]

Hi again. just thought I would include a pic of my control board amd circuit diagram. This has 3 speed controllers and the hydraulic pump switch on it. The pump switch is good to about 4 amps without heatsink but can go up to 12 amps with a heatsink.
The pump switch is the bottom PIC chip. Not sure if the diagram will be big enough as an attachment.

[rc_farmer]

Is the pump all you can run off this board?

[iaindunn]

No the board has 3 escs' on board as well, 1 for slew and 2 for track motors and a 5v supply .

[Espeefan]

Originally Posted by fhhhstix

Full sized equipment recommend full rpm for full pump out put as to not starve the hyd components and also not to over demand the pump. I would think the same hyd principles would apply to our stuff as well and if it is a heat issue you are concerned about a hyd cooler is a cheaper and more effective solution.

Travis

I would guess that like most things in life, there are always exceptions. Since the hydraulic pumps are coupled to the engine, it's not uncommon for the pump RPM to vary all the time too. Look at a wheel loader, for example. Lots of driving forward and backing up. In between, steering when the engine is winding down, or at idle, and lifting or dumping the bucket. Pump (oil flow) output varies quite a bit. Now something like a back-hoe or an excavator is a totally different story. Maybe even a skid-steer, but the demand for hydraulic flow on a machine that is constantly moving, and uses hydraulic motors for the drivetrain also, actually needs good flow, and maximium pump output. Then we also could consider the variable displacement hydraulic pumps, that put out more flow, when it is demanded, regardless of engine RPM.

So I would think on a small scale model there is no reason why the pump can't be throttled back to reduce heat, and increase battery life. Sounds like a win win situation to me. Heat is the worst enemy for a hydraulic system, next to oil contamination. Yes, you could put a heat exchanger on any hydraulic system, but on a scale model, it would be easier and cheaper to throttle back the pump, or shut it off completely.

Out in industry, where I work, we are starting to see some hydraulic pumps run with electric motors, and variable frequency motor drives, which throttle the motor and pump RPM back, when the flow is not needed. The worst is when an operator walks away from a machine and leaves it running. The oil is constantly going over the relief valve and the motor is drawing more power in doing so, while also heating up the oil for the next few hours. Yes, the heat exchangers cool the oil too, but it is still getting warmer then it normally would, if the machine is cycling.

[fhhhstix]

Nate the cooler and fan are under $30 so I would say it is probably a little cheaper than a speed controller. To me it just seams like a wast of money and time to deal with a simple issue.

Travis

[doodlebug]

One thing to consider, the newer John Deere excavator's with "Power Wise" do speed up and slow down depending on hydraulic load. Sound's weird to hear them speed up under heavier load, maybe 2-300 rpm. My neighbor has a 160 Deere, that doe's it. And yes this is separate from the "auto idle" function.
Later, Neil#2 aka doodlebug.

[egronvold]

Originally Posted by fhhhstix

Nate the cooler and fan are under $30 so I would say it is probably a little cheaper than a speed controller. To me it just seams like a wast of money and time to deal with a simple issue.

Travis

You can get a suitable ESC for $8 But you do need a radio with at least 2 free mixes.

[iaindunn]

Here is a link to short video showing my excavator running with my control board. I have it programmed so when all sticks are neutral hydraulic pumo will switch off after 2 seconds. Hope you find it useful. If you want further details of this board and how to build program one let me know and I'll post otherwise I'll assume it's of no interest.
Cheers

http://www.youtube.com/watch?v=JaDPkz3Z5JA

[Car5858]

Originally Posted by iaindunn

Here is a link to short video showing my excavator running with my control board. I have it programmed so when all sticks are neutral hydraulic pumo will switch off after 2 seconds. Hope you find it useful. If you want further details of this board and how to build program one let me know and I'll post otherwise I'll assume it's of no interest.
Cheers

http://www.youtube.com/watch?v=JaDPkz3Z5JA

looks and works great.

Originally Posted by egronvold

You can get a suitable ESC for $8 But you do need a radio with at least 2 free mixes.

The cooler needs to be on a sperate circut, with its own circ pump. This is the way I have seen them set up. Allowing independent operation will allow the hyd oil to be cooled when the main pump is in shut down mode.

[pugs]

A cooler could easily be set up with just the one pump. Placed in the return to tank line from the control valve block and with a low psi bypass around it.

[doodlebug]

Hey Iain, thank's for sharing the controller info, over my head, but still neat!
Later, Neil#2 aka doodlebug.

[tfmacz]

Hi Iain
is is possible you could share the pic hex files for both the H-Bridge drive pics and the pump switch pic.

I can program pic's and a couple local guys would like to play with you design.

Thanks for sharing

Originally Posted by iaindunn

Hi again. just thought I would include a pic of my control board amd circuit diagram. This has 3 speed controllers and the hydraulic pump switch on it. The pump switch is good to about 4 amps without heatsink but can go up to 12 amps with a heatsink.
The pump switch is the bottom PIC chip. Not sure if the diagram will be big enough as an attachment.

[iaindunn]

Would you prefer the assembler as you then play around with it in mplab ?
I have posted the assembler for the pump switch above:
Below is the speed control based on microchips simple esc desigen but rewritten to give forward and reverse. The track motor controls are on one 12f675 and are simply forward and reverse for both run off toggle switches on my trasnmitter. I did do a 2 speed version but didn't gain much from it:

Any questions just ask.

Iain

[tfmacz]

I am looking to take some shortcuts to start with. So If you have the .hex binary files would save me some time initially. I use Eagle for pcb design and I make prototype pcb's on a small cnc mill built for the purpose.
I have your schematic diagram, could you post an image of the copper side of the pcb? It will save me some layout time.
I don't currently have mplab installed anywhere.

Looks like I will have to rebuild my development box.
Thanks for all your help.
Ted

Originally Posted by iaindunn

Would you prefer the assembler as you then play around with it in mplab ?
I have posted the assembler for the pump switch above:
Below is the speed control based on microchips simple esc desigen but rewritten to give forward and reverse. The track motor controls are on one 12f675 and are simply forward and reverse for both run off toggle switches on my trasnmitter. I did do a 2 speed version but didn't gain much from it:

Any questions just ask.

Iain

[fhhhstix]

Originally Posted by Espeefan

I would guess that like most things in life, there are always exceptions. Since the hydraulic pumps are coupled to the engine, it's not uncommon for the pump RPM to vary all the time too. Look at a wheel loader, for example. Lots of driving forward and backing up. In between, steering when the engine is winding down, or at idle, and lifting or dumping the bucket. Pump (oil flow) output varies quite a bit. Now something like a back-hoe or an excavator is a totally different story. Maybe even a skid-steer, but the demand for hydraulic flow on a machine that is constantly moving, and uses hydraulic motors for the drivetrain also, actually needs good flow, and maximium pump output. Then we also could consider the variable displacement hydraulic pumps, that put out more flow, when it is demanded, regardless of engine RPM.

So I would think on a small scale model there is no reason why the pump can't be throttled back to reduce heat, and increase battery life. Sounds like a win win situation to me. Heat is the worst enemy for a hydraulic system, next to oil contamination. Yes, you could put a heat exchanger on any hydraulic system, but on a scale model, it would be easier and cheaper to throttle back the pump, or shut it off completely.

Out in industry, where I work, we are starting to see some hydraulic pumps run with electric motors, and variable frequency motor drives, which throttle the motor and pump RPM back, when the flow is not needed. The worst is when an operator walks away from a machine and leaves it running. The oil is constantly going over the relief valve and the motor is drawing more power in doing so, while also heating up the oil for the next few hours. Yes, the heat exchangers cool the oil too, but it is still getting warmer then it normally would, if the machine is cycling.

Thanks for the explanation. Yes I did take offence!

I work for the CAT Rental Store and work on all kinds of hyd systems by a lot of different manufactures JLG, Broderson, LULL, Bell, Trail King, and the list goes on but hay my boss will be glad you explained to me how it works.

All I am saying is why over complicate some thing you can take care of with a cheap switch or cooler.

Originally Posted by egronvold

You can get a suitable ESC for $8 But you do need a radio with at least 2 free mixes.

$8 esc shipped from where and will last how long and who warranties it.

Travis