Abstract:
An electronic digital governor assembly includes a case, a printed circuit board housed within said case, the printed circuit board having control circuitry configured for controlling at least one parameter of an energy production device, and a user interface including a digital display for displaying a value of the at least one parameter and at least one button for selectively adjusting the value.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/413,693, filed on Nov. 15, 2010, entitled “ELECTRONIC DIGITAL GOVERNOR,” which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to speed control devices and, more particularly, to an electronic digital governor for controlling functional parameters of a generator or reciprocating engine. 
     BACKGROUND OF THE INVENTION 
     Known governors are generally analog in nature and utilize analog controllers that control potentiometers to control various functions of energy production devices, such as generators and reciprocating engines. For example, such governors are designed to control the speed of the generator/engine through the adjustment of one or more knobs or similar mechanical means. Generally these known analog governors have a separate knob for controlling each individual operational parameter of the generator or engine. As will be readily appreciated, however, controlling generator/engine parameters though knobs is generally imprecise, as a user cannot see the exact value that is being set for a given parameter. 
     In view of the above, there is a need for a governor that allows for the precise adjustment of various operational parameters utilizing a single button or a single set of controls. In addition, it is desirable to provide a governor having an display readout so that a user can see exactly the value of an operational parameter being set. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an electronic digital governor. 
     It is another object of the present invention to provide an electronic digital governor having an intuitive user interface. 
     It is another object of the present invention to provide an electronic digital governor that can replace existing mechanical governor systems. 
     It is another object of the present invention to provide an electronic digital governor that allows for the precise adjustment of various operational parameters utilizing a single set of controls. 
     It is another object of the present invention to provide an electronic digital governor that allows for engine speed control. 
     It is yet another object of the present invention to provide an electronic digital governor that is sealed to prevent permeation of potting compounds and moisture. 
     It is yet another object of the present invention to provide an electronic digital governor that can be operated in temperatures as low as −40 degrees Celsius. 
     It is yet another object of the present invention to provide an electronic digital governor that is tolerant to component stack-up issues. 
     It is yet another object of the present invention to provide an electronic digital governor that has improved heat dissipation compared to existing devices. 
     These and other objectives of the present invention, and their preferred embodiments, shall become clear by consideration of the specification, claims and drawings taken as a whole. 
     An electronic digital governor assembly according to an embodiment of the present invention includes a case, a printed circuit board housed within said case and having control circuitry configured for controlling at least one parameter of an energy production device, and a user interface including a digital display for displaying a value of the at least one parameter and at least one button for selectively adjusting the value of the parameter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below: 
         FIG. 1  is a front, perspective view of an electronic digital governor in accordance with an embodiment of the present invention. 
         FIG. 2  is a front elevational view of the electronic digital governor of  FIG. 1 . 
         FIG. 3  is an exploded, perspective view of the electronic digital governor, shown without a printed circuit board (PCB). 
         FIG. 4  is an exploded, perspective view of the PCB and terminal block of the electronic digital governor of  FIG. 1 . 
         FIG. 5  is a perspective view of the PCB and terminal block of the electronic digital governor of  FIG. 1 , shown in an assembled state. 
         FIG. 6  is a rear, perspective view of the electronic digital governor of  FIG. 1 , showing the PCB seated in the casing. 
         FIG. 7  is a rear elevational view of the electronic digital governor of  FIG. 1 , showing a potting compound encasing the PCB. 
         FIG. 8  is a front elevational view of the electronic digital governor of  FIG. 1 , showing a user interface thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 and 2  illustrate an electronic digital governor  10  according to one embodiment of the present invention. As shown therein, the governor includes a generally rectangular outer case  12  having a plurality of apertures  14  formed therein through which various buttons of a keypad are provided to control operation of the governor  10 , as discussed hereinafter. The case  12  also includes a rectangular opening  16  adjacent the bottom thereof to permit access to a terminal block secured to the circuit board of the governor  10 , and a generally rectangular aperture  18  formed in the center of the case  12  for a digital display. As further shown in  FIG. 1 , the case  12  has a plurality of tabs  20  for mounting the governor  10  in a control cabinet or engine mounted enclosure. In an embodiment, the governor  10  is engine compartment mountable. In addition, the case  12  is also formed with a plurality of fins  22  for dissipating heat from the circuit board, as discussed below. 
     With reference to  FIG. 3 , the internal components and the alignment of such components within the case  12  is shown. In particular, the governor  10  includes a gasket  24 , a polycarbonate plate  26 , a LCD display  28 , a LCD back plate  30 , a pair of elastomeric connectors  32  and a keypad  34 . The gasket  24  includes a plurality of apertures sized, shaped and positioned to correspond to the apertures  14 ,  18  formed in the case  12 . In particular, the gasket  24  includes apertures  36  for the buttons of the keypad  34  and an aperture  38  for the LCD display  28 . The gasket  24  is seated against the housing and is located in place by pins (not shown) on the case  12  that are received in locating holes  40  formed in the gasket  24 , and by a plurality of internally threaded posts  42  integrally formed with the case  12 . In an embodiment, one or more of the posts  42  may be stepped. 
     As further shown in  FIG. 3 , the polycarbonate plate  26  also includes apertures  44  that correspond to the size and shape of the apertures  36  in the gasket  24  and the apertures  14  in the case  12 . The plate  26  is also formed with a transparent window  46  that is aligned with aperture  38  of the gasket and aperture  18  of the case. As will be readily appreciated, the transparent window  46  protects the LCD display  28  which is positioned behind the window  46  from moisture permeation and from impact by debris. The plate  26  is formed with a plurality of stepped bosses  48  that are aligned with the threaded posts  42  of the case  12 . During assembly, the stepped bosses  48  are received on the threaded posts  42  to properly position the plate  26  with respect to the case  12  and the gasket  24 . As discussed in detail below, the gasket  24  provides a substantially air tight and water tight seal between the polycarbonate plate  26  and the case  12  such that no moisture or debris can the interior of the case  12  through the LCD aperture  18 . 
     With further reference to  FIG. 3 , the LCD  28  display is generally rectangular in shape and is designed to fit within the transparent window  46  of the polycarbonate plate  46  such that the display  28  is visible from the front of the governor  10  through aperture  18 . While the preferred embodiment of the present invention utilizes a LCD display, other types of displays known in the art, such as LED and the like, may also be used without departing from the broader aspects of the present invention. Once the LCD display  28  is positioned within the window  46 , the LCD back plate  30  is laid on top of it. Elastomeric connectors  32  are received in a space above and below the back plate  30 . The elastomeric connectors  32  may be ZEBRA connectors or other types of connectors known in the art, and are utilized to connect the LCD display  28  to the circuit board. 
     The keypad  34  includes a plurality of buttons  50  that are sized and shaped so as to be received through apertures  44  in the plate  26 , apertures  36  in the gasket  24  and apertures  14  in the case  12 . The buttons  50  protrude from the front of the case  12  so that they be accessed by a user to control operation of the governor  10 , as discussed below. In the preferred embodiment, the keypad  34  is formed from an elastomeric material. Importantly, the keypad  34  also has a gasket  52  extending around a periphery thereof that is received in a correspondingly shaped track  54  in the polycarbonate plate  26 . As will be readily appreciated, the engagement of the gasket  52  within the track  54  serves to properly locate the keypad  34  within the case  12 . In addition, this engagement also creates an air-tight and moisture-tight seal so that any moisture or debris is prevented from entering the governor  10  through the button apertures  14  in the case  12 . 
     Turning now to  FIGS. 4 and 5 , the construction of the printed circuit board (PCB)  56  of the governor  10  is shown. The circuit board  56  is generally of the type known in the art and includes a gasket connector  58  on top of which a terminal block  60  having a plurality of terminals  62  is mounted. A thermal strip or a section of thermal tape  64  is disposed on a portion of the circuit board  56 . The circuit board  56  also includes a plurality of screw apertures  66  sized to receive screws  68 , as shown in  FIG. 6 . The screw apertures  66  are located so as to align with the threaded posts  42  of the case  12 . 
     As shown in  FIG. 6 , the circuit board  56  is received within the case  12  after the other components have been stacked therein, such that the terminal block  60  protrudes through the opening  16  in the front of the case. A plurality of screws  68  are inserted through the screw apertures  66  in the circuit board  56  and are received in the threaded posts  42 . The screws  68  are then torqued down to secure the circuit board  56  to the case  12 . 
     In connection with securing the circuit board  56  to the case  12 , the stepped bosses  48  of the polycarbonate plate  26  are an important aspect of the present invention. In particular, the stepped bosses  48  provide a crush feature that eliminates stack up issues, allows the circuit board  56  to sit line to line with the case  12  and provides a pre-load for the gasket  52  integrated with the elastomeric keypad  34 . 
     Notably, if there are any tolerance issues with the stacked components, some of the components may not be properly seated. As the screws  68  are torqued down, however, the stepped bosses  48  of the polycarbonate plate  26  crush or yield so that the thermal tape  64  of the circuit board  56  comes into direct contact with a raised land  70  formed on the back of the case  12 . As will be readily appreciated, heat generated through normal operation is directed to the thermal tape  64  and transferred, through conduction, to the raised land  70  of the case. The heat transferred to the raised land  70  is then dissipated through the fins  22  formed in the front of the case  12 . As will be readily appreciated, then, the crush feature provided by the stepped bosses  48  ensure that all of the components are properly aligned and seated and compensate for any dimensional inaccuracies in manufacturing of the components. In this manner, it also ensues that the elastomeric connectors  32 , the buttons  50  and back of the keypad  34  are in contact with the circuit board  56 . 
     Once the circuit board  56  is installed and torqued down so that the thermal tape  64  comes into direct contact with the raised land  70  of the case  12 , a potting compound  72  is poured on the back side of the case  12 , as shown in  FIG. 7 , to completely seal the internal components, including the circuit board  56 , within the case  12 . Notably, because of the various seals, such as gasket  52  and the seal between the polycarbonate plate  26  and gasket  24 , the potting compound  72  is unable to penetrate the display  28  or the buttons  50 . Accordingly, this obviates the need for masking, which is necessary when potting existing electronic devices. 
     Importantly, as discussed above, the LCD display  28  is in a sealed cavity between the polycarbonate plate  26 , the elastomeric keypad  34  and the circuit board  56  (contact between the keypad  34  and circuit board  56  creates an air-tight and moisture-tight seal. A temperature sensor (not shown) on the circuit board  56  within this cavity monitors a temperature within the cavity during operation of the governor  10 . If the temperature within the cavity drops below a predetermined value necessary for proper operation, the sensor will detect this drop and a processor will direct heat to resistors  74  on the circuit board  56  (also within the cavity) to heat the cavity to a sufficient operating temperature. As a result, the governor  10  of the present invention is capable of operating in temperatures reaching −40 degrees Celsius. 
     The governor  10 , and the circuit board  56  in particular, contains control circuitry to control operation of an engine or governor, as alluded to above. In particular, the governor has an advanced microprocessor with enough computational power, memory, and I/O support (through the terminal block  60 ) to support an enhanced PID control loop, user interface and an optional J1939 Bus interface. To install the governor  10  an actuator and battery are connected to terminals A, B, E and F of the terminal block  60 , as shown in  FIG. 8 . Magnetic speed sensor wires are connected to terminals C and D of the terminal block  60 . The governor  10  detects the speed of the generator or engine by picking up the gear teeth on the flywheel of the generator or engine, and outputs a signal to control fuel rack. In particular, fuel rack may be adjusted through the user interface in dependence on the measured/detected speed. Importantly, the electronic digital governor  10  constantly monitors the magnetic pickup for speed detection. 
     The user interface is an important aspect of the present invention. As discussed above, existing governors are analog in nature and engine parameter adjustment has been effectuated by turning various small knobs. In stark contrast, the present invention is digital and provides a user interface having a quickset menu system. In an embodiment, upon starting the engine, the three most required parameters, gain stability and deadtime, appear on the display  28  and are immediately accessible. As will be readily appreciated, in contrast to existing analog governors, the LCD display  28  of the governor  10  of the present invention allows a user to read the exact speed of the engine from the front of the device, in real time. In addition, the governor  10  of the present invention allows a user to see the percent throttle (i.e., percent modulation of fuel), current to the actuator, etc., which is simply not possible with existing analog devices. 
     As shown in  FIG. 8 , the LCD display  28  has a variety of data or parameter fields including a numerical field  76  for displaying parameter numerical values, an alphanumeric field  78 , a parameter menu  80 , a warning indicator  82  and a throttle or delta speed graph  84 . On the display  28 , a user may modify a parameter by pressing and holding the appropriate column button  86 ,  88 ,  90  while simultaneously pressing either the UP and DOWN arrow  92 ,  94 , respectively, to increase or decrease the value accordingly. Importantly, the user interface provides for the incremental tuning of parameters, with intuitive acceleration when a button is held down for a duration. To prevent unauthorized access to the governor  10 , the user interface can be locked. The governor control circuitry may automatically time out the display, should an operator leave it unattended. 
     As discussed above, the user interface can display throttle percent or the difference in commanded and actual speed. Moreover, droop max load, as measured by the current actuator, is settable. Importantly, and in contrast to existing analog governors, the governor  10  of the present invention can be used with a wide range of actuators. 
     During operation, while governing, the governor  10  will display the current RPM and the percent of throttle being applied. The RPM is displayed in the alpha numeric area  78  and the percent throttle is on the graph  84 . By pressing either the UP or DOWN arrow, the user can change the alphanumeric area  78  to display the numerical percent throttle (in which case the bar graph  84  will then represent the difference between the actual RPM and the desired RPM). 
     As noted above, the governor  10  and its control circuitry provide switch inputs for droop and idle and a standard accessory input for connecting to load sharing/synchronizing controls. In addition to the above, the electronic digital governor  10  contains START FUEL and FUEL RAMP settings to eliminate or reduce black smoke during startup. START FUEL represents the initial power to apply to the actuator during cranking (e.g., 0% for fully closed, 50% for half open, 100% for fully open, etc.). FUEL RAMP represents how fast to apply fuel as the engine starts. As will be readily appreciated, the ability to precisely adjust these settings is crucial, as poor PID settings can affect the response. 
     The governor  10  also has a variable speed/trim input which accepts a 5 kOhm potentiometer. Generally, the trim function may be utilized to perform finer adjustments such as in generator frequency. Variable speed is used to operated in a larger RPM range. An accessory input (M in  FIG. 2 ) on the terminal block  60  accepts input signals from load sharing units, auto synchronizers, and other governor system accessories. 
     While the invention had been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various obvious changes may be made, and equivalents may be substituted for elements thereof, without departing from the essential scope of the present invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention includes all embodiments falling within the scope of the appended claims.