Innovatia Laboratories

VC1 Valve Controller

Description

The VC1 valve controller mounts on the gearbox of a 12 rpm, 40 lbf-in, 12 V gearmotor and couples to ball valves or other rotationaslly-actuated devices. A shaft coupler (not supplied) connects the valve stem to the gearbox shaft.

Ball valves used with cryogenic fluids (such as liquid oxygen) have a drain hole in the ball perpendicular to the main ball channel, to drain the channel to the valve exit when the valve is off. Bidirectional rotation is required to assure that the venting drain opens to the exit side of the valve.

The VC1 direction command allows closing or opening the valve. When the commanded position has been reached, either the CLOSED or OPENED output is asserted, indicating completion of the command. 

Use of the second enable command input results in both direction and on-off control capability required for a fluidic feedback loop.

Valve switching speed and torque are maximized by use of low-resistance, all n-channel, transistor switches.

Electrical Interface

The VC1 has eight male 0.25 inch quick-disconnect electrical connectors for its electrical interface:

  1. GND: Power ground: connects to minus (black) terminal of 12V battery or power supply.
  2. +12V(U): Unregulated 12 volt power source; a 12 V battery or power supply positive (red) terminal.
  3. COMMON: positive common supply for output signal indicators OPENED and CLOSED. This terminal is connected to the positive output of the supply driving these signal indicators. The default connection is +12V(U) through jumper J11, behind the COMMON connector. For some indicators, such as a computer input, COMMON should be a +5 V supply instead. In this case, cut out the J11 jumper and connect the desired positive supply to COMMON and its ground to GND.
  4. OPENED: High (positive) output if valve is in the opened position. A 33 kW pull-down resistor keeps this output at ground level with no load attached. Maximum current is 200 mA. Output is short-circuit protected by a series 100 W resistor.
  5. CLOSED: High (positive) output if valve is in the closed position. A 33 kW pull-down resistor keeps this output at ground level with no load attached. Maximum current is 200 mA. Output is short-circuit protected by a series 100 W resistor.
  6. O/C: Open/close command: if low (grounded) or left open the valve is commanded closed; if high (> 4 V, such as +12V(U)), the valve is commanded open. When a change in command occurs, OPENED and CLOSED will become deasserted until the commanded state is achieved.
  7. MOTOR+: Positive (red) gearmotor lead connection.
  8. MOTOR- : Negative (black) gearmotor lead connection.

The motor leads should already be attached to terminals 7 and 8.

Installation

Mount the VC1 onto a flat sheet of metal with the valve mounted on the opposite side. A hole in the sheet allows the valve stem to be coupled to the VC1 gearbox shaft. The coupler on the VC1 side must accommodate a 0.3125 inch diameter shaft. The VC1 is held onto the sheet by screwing #10 standoffs onto the four corner mounting threads. Screw them down until they are in firm contact with the circuit-board. Use #10 screws to fasten the other ends of the standoffs to the sheet metal, through four holes drilled in the sheet.

Before installing the shaft coupler to the valve, be sure that the position sensor shaft collar is correctly mounted on the gearbox shaft. This collar slips onto the gearbox output shaft and has button magnets attached to opposite sides of the collar (about 180 degree spacing).

Wiring Diagram

The VC1 is typically connected as shown below:

For remote (manual) valve control:

     

  1. Connect the O/C terminal to the center (common) terminal of a single-pole, double-throw switch. Connect the other two switch terminals to +12(U) and GND.
  2.  

  3. Connect COMMON to +12V(U) and OPENED and CLOSED to 12 V incandescent bulbs or LEDs with 680 W series current-limiting resistors.
  4.  

  5. Connect a 12 V battery or power-supply to +12V(U) and GND. Be sure to connect the polarity correctly. A power switch and 2 A fuse in series with the +12V(U) line is highly recommended.
  6.  

  7. Power the VC1. The shaft will turn to the closed position if O/C is at a low voltage (near ground) or open.
  8.  

  9. By flipping the O/C switch, the shaft should turn about 90 degrees. Note shaft turning direction from closed to opened. Then place the switch in the closed position. Align the valve stem so that the valve is closed and the valve ball vent (if any) is on the exit side. Then couple the valve stem to the shaft coupler.
  10.  

  11. Test the loaded VC1 by changing the O/C state and observe motion. If the valve stem is turned the wrong direction, reverse the collar magnets and test again. (See On/Off Position Adjustment.)

For automated valve control, the O/C input can be driven by a TTL-level output, as is typical of most computer digital I/O lines. The COMMON terminal must be connected to a +5 Vsupply and the OPENED and CLOSED outputs from the VC1 are then TTL compatible.

Power supply overvoltage protection is not ordinarily supplied with the VC1. The distribution supply powering the VC1 should have transient overvoltage protection to limit power-supply voltages to < 18 V. The VC1 can be optionally supplied with overvoltage transient suppressors. Contact supplier for details.

On/Off Position Adjustment

The on- and off-position magnets are magnetically attached to opposite sides of the shaft collar. After the valve is coupled to the shaft, adjust their location for correct on and off positions. The magnets are mounted on the collar with opposite magnetic polarity.

If the magnets should become removed, bring faces of the two magnets together and orient the faces so that they attract. The two attracting faces should be oriented outward on the collar. Their position on the collar should be adjusted for desired on and off valve positions and for access to the collar setscrew. After correct positions are found, hot-glue (cyanoacrylate or epoxy) them in place. Remove glue on the outward faces to avoid interference with the sensors. Be careful to avoid damaging the electronics while adjusting the collar. positions. Glue magnets in place on the collar.

If the shaft rotates about 270 degrees instead of 90 degrees, flip them both over or else exchange the two magnets by sliding them around the collar, keeping their orientation (outward faces still point outward). Then adjust each magnet for desired on and off

Proportional Control

Pin 8 of the PLD IC is the /ENABLE input. When held low, it commands the gearmotor to be on in the direction set by the O/C input..

Specifications

Mechanical Output

Rotational speed, 12 V supply, full load: 12 rpm.

Valve open/close time, quarter-turn: 1 s.

Full-load torque: 4.5 N-m or 40 lbf-in.

Mechanical Characteristics

Weight: 5.56 N or 1.25 lbf

Size: 102  70   76 mm or 4 2.75 3 inches

Output shaft: 7.94 mm or 0.3125 (5/16) in dia., slotted; 12.7 mm or 0.5 inch length.

Environmental Characteristics

Operating temperature range: - 40 to +70  C.

Relative humidity: non-condensing.

Power Supply Input: +12V(U), GND

Voltage input range: 10 V to 16 V between +12V(U) and GND.

Quiescent supply current:   0.1 A.

Maximum supply current (motor running while switching):   1.3 A.

Overvoltage transient protection: optional.

Undervoltage lockout: below 9 V, the system reset state is asserted. (See Operating States.)

Open/Close Command Input

O/C input CLOSE voltage: 0 -  1 V.

O/C input OPEN voltage: 3 V -  18 V.

Input resistance: > 10 kW .

State Outputs: OPENED, CLOSED

OPENED and CLOSED asserted-state output voltage: voltage at COMMON terminal. If jumper J11 is installed (not broken), this is the voltage of +12V(U).

OPENED and CLOSED asserted-state maximum current: 200 mA. These outputs are overcurrent protected by 100 W series resistors.

OPENED and CLOSED unasserted-state outputs: 33 kW to GND in series with 100 W; 0 V out when unloaded.

Output Shaft Position Sensing

Position is sensed by two Hall-effect devices. U11 senses CLOSED position; U13 senses OPEN position. Each sense the polarity of one of the two magnets on the shaft collar. The two magnets are opposite in polarity and are NdFeB (Neodymium Iron Boron) high-coercivity button magnets.

Operating States

The PAL logic (U15) is programmed for six logic states which are output on pins 17 (/S1) and 18 (/S0) and 14 (/S2) of U15. Logic high (1) states and low (0) states are TTL compatible.

STATE

/S2

/S1

/S0

NAME

0

1

1

1

CLOSING

1

1

1

0

CLOSED

2

1

0

1

OPENING

3

1

0

0

OPENED

4

0

1

1

RESET

5

0

1

0

MOTOR-REVERSAL DELAY

Major rules of state change are:

1. If CLOSED and O/C goes high, go to OPENING. Rotate motor CW as viewed from gearbox shaft toward valve shaft.

2. If OPENING, go to OPENED if OPENED position sensor asserts. If O/C command goes low (close), go to DELAY and then to CLOSING.

3. If OPENED and O/C is goes low, go to CLOSING. If OPENED sensor unasserts, go to OPENING. Rotate motor CCW as viewed from gearbox shaft toward valve shaft.

4. If CLOSING, go to CLOSED if CLOSED position sensor asserts. If O/C command goes high (open), go to DELAY and then to OPENING.

Power reset causes the RESET state to be asserted. When it is unasserted, if the CLOSED or OPENED position sensor is asserted, the state will go to CLOSED or OPEN accordingly. If neither is asserted (valve is partially open), the CLOSING state is asserted next, causing the valve to be closed.

For CCW, H-bridge upper left (LU) and lower right (RL) MOSFETs are on; for CW (while OPENING), RU and LL MOSFETs are on. During current limiting (ILIM), all MOSFETs are off. Motor current limiting occurs at about 1.5 A.

21SEP98

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