Abstract:
A device for delivering a preset volume of fluid, such as oil, includes a casing ( 10 ) with an inlet port ( 16 ), an outlet port ( 17 ) and supply passages ( 22, 24 ) for flow of fluid from the inlet port ( 16 ) to the outlet port ( 17 ). A valve including a valve member ( 24 ) is situated to control the flow of the fluid through a valve chamber ( 23 ). The valve is manually actuated to an open position and held by momentary energization of a latching solenoid ( 36 ). When the fluid volume reaches a preset volume, the latching solenoid ( 36 ) is energized again to allow the release the valve member ( 24 ) to return to a closed position. In the event of a battery low condition, the latching solenoid ( 36 ) can be disabled, so that the valve can only be held open manually, thereby preventing an electrical failure with the valve open. A manual push button ( 21 ) is directly connected to the valve member ( 24 ) for closing the valve manually. A method for controlling the dispensing of a fluid is also disclosed.

Description:
TECHNICAL FIELD 
     The invention relates to metering guns or nozzles for dispensing a lubricating fluid. 
     BACKGROUND ART 
     In the field of vehicle service, handheld metering guns or nozzles are used to dispense predetermined amounts of a lubricating fluid, such as oil. The device has a lever that is squeezed against a handle to begin operation. The metering portion of the device then measures the amount of fluid passing through the device and closes a valve when a preset amount of the fluid has been dispensed. Such devices are useful in servicing vehicles using bulk supplies of oil or other lubricants. The device also has other industrial applications. 
     In the prior art, such devices have used mechanical metering mechanisms. These mechanisms have many parts that are subject to wear. 
     Electronic control offers a lower cost of manufacture, but to obtain these benefits, certain problems in converting to an electronic device must be overcome. 
     For convenience of use and mobility, such electronic devices must have their own power supply, typically provided by batteries. With batteries there are problems of battery life and assuring that the batteries do not fail with the valve in an open position. 
     An object of the present invention is to provide an electronically controlled metering device, which is less expensive to manufacture and easier to maintain than its mechanical predecessor. In addition, the device is to be protected from commencing a battery cycle when the battery is too low. 
     SUMMARY OF THE INVENTION 
     The invention is incorporated in a method and device for dispensing a lubricating fluid, in which the device is protected against low battery conditions, by disabling an electronically actuated latching device and relying on manual operation. An electronic control circuit monitors battery level and performs the disabling function when necessary as well as providing visual indications to the user. A manual override push button is also provided. 
     The device is conveniently programmable for multiple batch sizes and is operable in an automatic shut off mode. 
     Other objects and advantages of the invention, besides those discussed above, will be apparent to those of ordinary skill in the art from the description of the preferred embodiments which follow. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate examples of the invention. Such examples, however, are not exhaustive of the various embodiments of the invention, and therefore, reference is made to the claims which follow the description for determining the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a device that incorporate he present invention; 
     FIG. 2 is a top plan view of the device of FIG. 1; 
     FIG. is a sectional view taken in the plane indicated by line  3 — 3  in FIG. 2; 
     FIG. 4 is an enlarged detail view of a display portion of the device of FIGS. 1 and 2; and 
     FIG. 5 is an electrical schematic of the electrical system in the device of FIGS. 1 and 2. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, the device of the present invention includes a casing  10 , primarily of molded plastic material, except for an exposed metal band, which is an outside edge of a metal band housing  11  seen in section in FIG.  3 . The casing  10  (FIG. 1) includes a head portion  12 , a rounded handle  13  extending from the head portion  12 , and a trigger guard portion  15  which extends from the head portion  12  and connects to a distal end of the handle  13 . The device includes a trigger  14 , provided as a metal lever, which when squeezed against the handle  13  to further operate a valve (not shown in FIG. 1) which opens and closes to control the flow of liquid. The liquid enters through inlet port  16  and exits through outlet port  17 . Chevron-shaped treads or projections  13   a  are spaced along the handle  13  to provide for a better grip. 
     The device also includes a bezel portion  18  which fits around a visual display  19  and a group of six programming keys  20  and one mechanical push button  21  to be described in greater detail below. 
     Referring to FIG. 3, lubricating liquid flows into inlet port  16  and through supply passage  22  to a valve chamber  23 . A valve member  24 , more specifically referred to as a valve spool, is arranged vertically in a valve seat for movement up and down to control liquid flow through the valve chamber  23 . On the other side of valve chamber  23 , a second, inclined, supply passage  25  connects to a metering chamber in which two eccentric metering gears  26  turn in response to liquid flow. The liquid flows through metering gears  26  and out of the outlet port  17 . 
     It can now be seen that button  21  is directly and mechanically connected to valve member  24 , and this is an emergency button  21  for closing the valve (as seen in FIG. 3) and shutting off liquid flow. 
     An electronic circuit board  27  is installed under the display  19  and programming keys  20  of the head portion  12  of the casing  10  (FIGS.  1  and  3 ). A large capacitor  28  is mounted on the circuit board  27  along with a microelectronic processor  29 , to reed switches  30 , to a display  19  and to other components to be described below. Power for the processor  29  is provided by four AAA-sized batteries  31  located within the trigger guard portion  15  of the casing  10 . 
     The processor  29  executes a control program stored in memory to count metering pulses generated by gears  26  and sensed through the reed switches  30  to units of flow and displays the value on display  19 . The display  19  is capable of showing flow parameters, including for example, total volume and rate of flow. 
     The metering gears  26  include permanent magnets (not shown). As the gears  26  and magnets rotate, they cause reed switches  30  to open and close due to the change in polarity of the magnetic field generated by the permanent magnets. The electrical pulses generated by the reed switches  30  are communicated to the processor  29  located on circuit board  27 . 
     The metering device  10  has a manual mode of operation and an automatic mode of operation. 
     In the manual mode, squeezing the trigger  14  towards the handle  13  causes the trigger  14  to contact and move a tip  33  of the valve member  24 , causing spool  24  to be lifted upward to a position in which valve chamber  23  communicates with supply passage  22 . Valve chamber  23  is also in communication with supply passage  25 , to complete a flow path for the liquid from inlet  16  to gears  26  and eventually to outlet  17 . The metering gears  26  rotate at a rate proportional to the flow rate of the liquid. 
     Once the user is satisfied with the volume of liquid dispensed and shown on display  19  (FIG.  5 ), the user releases the trigger  14 , which allows valve member  24  to return its initial or blocking position, assisted by a return spring  32  positioned along a portion of valve member  24 , and this causes the flow of liquid to stop. The final delivered volume is then read on display  19 . 
     Operation in the automatic preset dispense mode is similar to manual operation, except that the meter is programmed with the desired preset batch values prior to squeezing the trigger  14 . Once programmed, the processor  29  monitors the throughput of the meter and automatically closes valve  23 ,  24  to stop the delivery of the liquid at the programmed value. 
     Programming is accomplished by programming keys  20  in conjunction with display  19 . The meter can be programmed in various units up to a value of “999”. The display  19  can either count up to the programmed value or down from the programmed value to zero. Preset values for up to a total of six can be stored in the memory of processor  29  and recalled for repeat batches. 
     Once the batch programming is complete, the trigger  14  (FIG. 3) is pressed to initiate flow through the device  10 . In the automatic mode, however, the valve  23 ,  24  is latched in the open position by a ball  34  engaging in a groove  35  machined into valve member  24 . The ball  34  in turn is held in the groove  35  in the valve member  24  by the actuation of latching solenoid  36  to a latching position. The solenoid receives the energy required for this operation from capacitator  28 . The signal to operate the latching solenoid  36  is provided by processor  29 , which receives information about the valve member  24  position from sensing switch  37  (FIG. 3) mounted on the underside of circuit board  27 . The valve member  24  carries a flange  38 , and when the valve member  24  is moved upward, flange  38  contacts switch  37  to actuate it. The actuation of the switch  37  causes the discharge of the capacitor  28 . The movement of the valve member  24  causes the engagement of ball  34  in the groove  35  in valve member  24 . The processor  29  times the capacitor discharge for an interval, such as, for example, 25 milliseconds. When trigger  14  is squeezed toward handle  13 , switch  37  sends a signal to processor  29  which in turn controls the time of discharge of the capacitor  28 . This minimizes the energy required to latch valve member  24  in the open position, thus extending the life of batteries  31 . 
     At any time during the delivery of liquid in the automatic mode, the flow of liquid through the device  10  can be interrupted by pressing manual override push button  21 . Push button  21  is directly connected to valve member  24  (FIG. 3) and, when pushed, will force the ball  34  out of the groove  35  and unlatch magnetic latching solenoid  36 . Once unlatched, valve member  24  will be allowed to drop to the closed position to stop the flow of the liquid. The flow of liquid through the device can be resumed by once again by squeezing trigger  14  and restarting the automatic dispensing function. Flow will continue until the original programmed value is reached. 
     When a programmed batch value has been delivered, and absent operation of the manual push button  21 , the processor  29  sends a signal that allows the capacitor  28  to discharge, sending a reverse polarity pulse as the solenoid unlatching signal. This momentary pulse overcomes the latching function of solenoid  36  (FIG.  3 ), which releases ball  34  and allows valve member  24  to return to its position stopping the flow of liquid. 
     The processor  29  senses the available voltage of batteries  31  and determines if there is enough energy available to successfully operate the device. This battery sensing function operates at two levels. 
     If the battery voltage falls below a first specified value, the processor  29  turns on a low battery icon  38  (FIG. 5) on display  19  to inform the user that the batteries need to be changed. This first indication is informational only, and the device is allowed to continue to operate in all modes. 
     If battery voltage falls to a second, lower battery threshold value, the low battery indicator  38  on display  19  remains lit, but the device is not allowed to be operated in the automatic mode. Auto icon  45 , the digits  46 ,  48  and the count direction arrows  53  will all disappear from screen of the display  19 . This prevents a user from starting a preset batching operation that cannot be automatically terminated due to a lack of energy in the batteries  31 . At this point, however, the device can still be used in the manual mode until such time as batteries  31  cannot operate processor  29  or display  19 . 
     When the batteries are completely exhausted, the device can still be operated as a non-metering valve using the trigger  14  to control the flow of oil as long as the trigger  14  is squeezed against the handle  12 . 
     Referring to FIG. 5, an electronic control circuit  40  mounted on circuit board  27  includes processor  29 , which in the preferred embodiment, is provided by an MSP 430 microelectronic processor  29  with on-board memory available from Texas Instruments, Inc. A control program of instructions is stored in the on-board memory to carry out the control functions described herein. A EEPROM  41  is also connected to the processor  29  to store user settings and batch histories. A crystal oscillator circuit  42  provides timing signals for driving the processor  29 . The processor  29  reads inputs from programming keys  20 . It transmits data to display  19 , which has five major digits  43 , three unit-of-measure digits  44 , a low battery indicator  38 , an automatic mode indicator  45 , a digit  48  for indicating batch mode and three digits  46  for indicating batch amount. The processor  29  also transmits control signals to enable latching the solenoid  36  (SOL. LATCH) and to enable unlatching the solenoid  36  (SOL. UNLATCH). These are coupled to the solenoid  36  through power transistor circuits  47 . The processor  29  also senses input signals from reed switches  30  and trigger sensing switch  27 . The processor  29  senses the voltage of the batteries  31  through a battery check circuit  50 . The batteries supply six dc volts unregulated power to a voltage regulator circuit  49 , which supplies 3.5 dc volts power to the other circuitry in the control circuit  40 . The capacitor  38  is connected through a diode  51  to the batteries  31  to be charged by the batteries  31  to six dc volts unregulated power. 
     To program the device in the automatic mode, the “AUTO” key  20   e  (FIG. 4) is pressed until elements  43 ,  44 ,  45 ,  46  and  53  appear on the screen display  19  as seen in FIG.  5 . The device is now in batch programming mode. The first digit  48  next to the auto mode indicator  45  will be flashing. There are seven values,  0 - 6 . Pressing the “TOTAL/UP” key  20   d  (FIG. 4) will scroll the value from  0  to  6 . Value “0” is the off setting for the automatic mode. Leaving the device in this mode will disable the batch function. If the mode digit is incremented to “1”, the digits  46  can be set to a batch value using the the “10/HISTORY” key  20   a,  the “1” key  20   b,  and “0.1/FLOW RATE” key  20   c  to select the batch size. If the “RESET/RIGHT” key  20   f  is now pressed, the count up/count down arrow  53  will flash. The count can now be adjusted using the “TOTAL/UP” key  20   d.  During normal operations, if the device is in the count down mode, then pressing the “RESET/RIGHT” key  20   f  will clear the previous total and replace it with the value of the batch selection. Pressing the “RESET/RIGHT” key  20   f  in the count-up mode causes the main digits to be replaced with zeros. When all of the batch selections have been made, the “AUTO” key  20   e  is pressed again and held until the screen fills up entirely. The device will then automatically reset. Whichever batch mode number was flashing will now be the choice displayed on the screen, but the choice number digit itself will not be visible. This helps the user determine if they are in auto program mode or not. 
     Pressing the “TOTAL/UP” key  20   d  key, when not in a programming mode, will display the total volume of liquid that has passed through the device for three seconds, and then it will display the reset total for three seconds. It will keep alternating between these two totals. To clear the reset total, the “RESET/RIGHT” key  20   f  is pressed when the reset total is visible. The total is cleared by selecting the initial programming mode and changing the units from liters to pints, gallons, or quarts, or vice versa. A scale factor value can be viewed by pressing and holding both the “TOTAL/UP” key  20   d  key and the “AUTO” key  20   e.    
     The device displays the previous five batches. By simply pressing the “10/HISTORY” key  20   a,  and the screen will display the most recent batch volume. The display  19  will increment through all five previous batches as long as the key  20   a  is held. 
     To use the meter for batching, the desired value is entered and the count direction is determined as described above, and then the trigger is operated. When the desired volume is dispensed, the meter will stop the flow by closing the valve  23 ,  24 . If the user desires to top off at this point, the trigger  14  is operated once more and held until the desired result is met. The “RESET/RIGHT” key  20   f  is pressed when finished, and the meter is ready for the next batch. The “RESET/RIGHT” key  20   f  is pressed to clear an old batch and to start a new batch. A batch can be aborted by pressing the red manual push button  21 . 
     The device is capable of sensing and displaying the flow rate. With liquid flowing through the device, and the “0.1/FLOW RATE” key  20   c  is pressed, the rate will be displayed at the batch selection digits  46  until the key is released  20   c.  The flow rate screen will not appear if the key  20   c  is pressed with no flow present. 
     This has been a description of the preferred embodiments of the method and apparatus of the present invention. Those of ordinary skill in this art will recognize that modifications might be made while still coming within the spirit and scope of the invention and, therefore, to define the embodiments of the invention, the following claims are made.