Abstract:
A new solid state electronic position indicator used to determine the horizontal and longitudinal level attitude of a recreation vehicle. This device, mounted on the frame of the vehicle, senses an imbalance condition by relying on a gravity sensitive compound pendulum. The pendulum is rectangular in shape, rotating about a shaft mounted ball bearing. Movement of this pendulum is detected by the electronic sensing circuit. This circuit sends an electrical signal to a visual or audio receiver mounted within a control panel, remote from the sensor. The control panel is normally mounted on dash of tow vehicle. The signal display indicates which side or end of the recreation vehicle requires elevation to attain a level attitude required to safely operate the propane gas operated appliances, e.g. (refrigerator, hot water heater) and provide creature comfort.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to a device used in indicating the horizontal and longitudinal level attitude of a recreation vehicle; remote from said vehicle. 
     Heretofore the inclination of the horizontal and longitudinal axes of a recreation vehicle was determined by the use of a carpenters type bubble level. The ability to determine said level attitude remote from the recreation vehicle has been recognized and desired for some time. The past method is time consuming and even dangerous. Usually two people must perform the leveling task, the driver of the tow vehicle and another person. Communications between the driver and the second person are usually not good, due to the distance between the back of the recreation vehicle and the driver. Accidents occur causing injury to humans and damage to property. 
     SUMMARY OF THE INVENTION 
     This invention relates to a device that is attached to a recreation vehicle used for assisting the operator of the tow vehicle in the leveling process by means of providing an indication of whether or not the recreation vehicle is level, and if not, which side needs to be raised in order to bring the recreation vehicle to a level attitude condition. 
     The principal object of the invention is to provide instantaneous feedback, to the operator of the tow vehicle, of the current level attitude of the recreation vehicle; feedback which will assist him in the leveling process of the recreation vehicle. Heretofore, the process of leveling a trailer has been time consuming, requiring two people and has been unsafe. 
     Several objects of the invention are: 
     (A) Permits driver of tow vehicle to instantaneously determine whether or not the recreation vehicle is level. 
     (B) Personal safety is enhanced as the driver may single-handedly accomplish the task of leveling the recreation vehicle by simply placing a ramp behind the wheel of the, &#34;low,&#34; side of the trailer, and backing the trailer upon the ramp until the driver receives the, &#34;all level,&#34; signal from the dash mounted control panel. This operation completes the leveling procedure. This has normally been a two person operation, at times jeopardizing humans and machines. 
     (C) Invention should replace use of of the old bubble type level and will provide a unit that will accurately indicate which side or end of the recreation vehicle requires elevation to achieve a degree of levelness required to permit safe operation of the propane operated appliances as well as providing personal comfort. 
     (D) Provide an electronic device that is not affected by the changes in climate and weather. 
     (E) The display unit, mounted on the instrument panel, will be a practical as as well attractive addition to any tow vehicle. 
     (F) Further objects and advantages of this invention will become apparent from consideration of the drawings and ensuing description thereof. 
     
         ______________________________________CORDVIC NUMBERING SYSTEM______________________________________FIG. 1     Control/indicator consoleFIG. 2     Sensor unitFIG. 3     Sensor unit: level condition (top view)FIG. 4     Sensor unit: level condition (front view)FIG. 5     Sensor unit: tilted right (top view)FIG. 6     Sensor unit: tilted right (front view)FIG. 7     Sensor unit: tilted left (top view)FIG. 8     Sensor unit: tilted left (front view)FIG. 9     Schematic diagram11         control/indicator console12         control/indicator console face13         ON-OFF switch14         ON-OFF switch integral LED15         fuse holder16         fuse, 1 amp fast blow17         12 volt voltage source (from tow vehicle)18         R6,510 ohm19         R1,250 ohm20         CR120&#39;        CR221         Q121&#39;        Q222         B+ node23         R4,470 ohm24         Q325         CR5, green LED26         R3,470 ohm27         CR428         D229         R2,470 ohm30         CR331         D132         R5,1.3K33         Sensor unit34         Compound pendulum35         ball bearing36         pendulum shaft support37         pendulum shaft38         left side shock mitigation bumper39         right side shock mitigation bumper40         PC board41         Reference plane42         Sensor unit bottom surface43         Reference node45         Screw46         Spacer47         Bumper Support Screw48         Nut49         Washer50         Washer51         Nut______________________________________ 
    
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With reference to the accompanying five sheets of drawing: 
     FIG. 1 is an isometric view of a preferred embodiment of a recreation vehicle level indicator sensor unit incorporating the invention; 
     FIG. 2 is an isometric view of a preferred embodiment of a recreation vehicle level indicator control/indicator console incorporating the invention; 
     FIG. 3 is a schematic sectional top view of the recreation vehicle level indicator sensor enclosure of FIG. 1, when it is in a horizontal level condition; 
     FIG. 4 is a schematic sectional front view of the recreation vehicle level indicator sensor enclosure of FIG. 1, when it is in a horizontal level condition; 
     FIG. 5 is a schematic sectional top view of the recreation vehicle level indicator sensor enclosure of FIG. 1, when the recreation vehicle upon which the sensor is mounted is subjected to an imbalance to the right; 
     FIG. 6 is a schematic sectional front view of the recreation vehicle level indicator sensor enclosure of FIG. 1, when the recreation vehicle upon which the sensor is mounted is subjected to an imbalance to the right; 
     FIG. 7 is a schematic sectional top view of the recreation vehicle level indicator sensor enclosure of FIG. 1, when the recreation vehicle upon which the sensor is mounted is subjected to an imbalance to the left; 
     FIG. 8 is a schematic sectional front view of the recreation vehicle level indicator sensor enclosure of FIG. 1, when the recreation vehicle upon which the sensor is mounted is subjected to an imbalance to the left; 
     FIG. 9 is a schematic view of the circuitry which embodies the recreation vehicle level indicator of (FIG. 1 and FIG. 2) to provide electronic indications of the lateral position of the pendulum with respect to the desired level condition. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As depicted in FIGS. 1-2, the desired embodiment of a recreation vehicle level indicator is comprised of two main pieces, a control/indicator console and a sensor unit. This configuration allows for the remote mounting of the sensor unit from the control/indicator console. 
     The first piece, the control/indicator console, is generally referred to by reference number 11. Located on the face 12 is an ON-OFF switch 13 with integral lamp 14, fuse holder 15 and three indicator lamps 25, 27 and 30. The control/indicator console is mounted in the tow vehicle so as to be visible to the operator. For example, a typical mounting location would be on the tow vehicle&#39;s dashboard. 
     The second piece, depicted in FIGS. 2-4, is the sensor unit, generally referred to by reference number 33. It is suitably mounted to a horizontal structural member of the recreation vehicle with fastening screws. A typical mounting location would be the center of the front surface of the forward structural I-beam, located on the recreation vehicle foundation frame. 
     The main parts in the sensor unit, shown in FIG. 4, are the compound pendulum 34 mounted on shaft 36, shock mitigators 38 and 39 and pendulum position sensors (to be described in more detail later), comprising components 20,20&#39;,21 and 21&#39;, mounted on circuit board 40. The actual electrical components on the circuit board, as well as their interconnections are not shown for the sake of clarity. The relationship of the pendulum with respect to the pendulum position sensors shall be discussed in more detail later. 
     Indicator lamps 25, 27 and 30 are used to indicate whether or not the recreation vehicle, upon which the sensor unit is mounted, is in the desired level condition and if not, they are used to indicate which side of the recreation vehicle needs to be raised in order to bring it to a level attitude condition. For example, if lamp 27 is illuminated, this could indicate that the right side of the recreation vehicle needs to be raised. Lamp 25 could be used to indicate that the recreation vehicle is in the desired level attitude condition. Lamps 25, 27 and 30 could be any type of indicator device such as light emitting diodes (LEDs) In addition, they will be different colors to make it easier to distinguish between the different conditions they are indicating. 
     With reference to FIG. 4, when the longitudinal axis 41 of the compound pendulum 34 is perpendicular to an imaginary line lying in the plane of bottom surface 42 of the sensor enclosure 33, the compound pendulum 34 will be exactly, &#34;centered,&#34; and the device will indicate a, &#34;level,&#34; condition, hereinafter referred to as a pendulum null condition. 
     As depicted in FIGS. 4-5, a ball bearing 35 is press fitted in compound pendulum 34. The bearing, in turn, is mounted on rigid shaft 36. The bearing enables the pendulum to swing smoothly between the sets of positional sensors, responding to minute changes in the rotation of the sensor unit about the axis defined by the shaft 37 Each of the positional sensors consists of a light emitting diode 20 and photodarlington transistor 21. Located on either side of the pendulum, the diodes and photodarlington transistors of the separate sets are distinguished from one another by the use of primed numbers. Light emitting diode 20 emits electro-optical radiation in, for example, the infrared range and directs that radiation to associated photodarlington transistor 21. When the longitudinal axis of the pendulum is perpendicular to the bottom surface of the sensor enclosure, as depicted in FIGS. 4-5, the electrooptical radiation emitted by light emitting diodes 20 and 20&#39; is allowed to pass by the sides of compound pendulum and is detected by photodarlington transistors 21 and 21, respectively. When the sensor unit is not level, the pendulum will swing to one side as a response to the gravitational pull of the Earth. The path of electro-optical radiation will be blocked and the consequence is that the electronic circuitry, to be discussed in greater detail later, will detect the cessation of current flow in the affected photodarlington transistor and provide the appropriate indication as to which side needs to be raised in order to bring the recreation vehicle (upon which the sensor is mounted) to a level condition. Hereinafter the set of light emitting diode along with it&#39;s associated photodarlington transistor shall be referred to as an emitter detector pair. 
     As previously mentioned, electronic circuitry is provided to sense the lateral position of the pendulum with respect to the the emitter detector pairs. The accuracy and reliability of such circuitry being well suited for the application of determining whether or not a recreation vehicle is level 
     FIG. 9 is a schematic of such circuitry. The power source 17 for the device is provided by the tow vehicle and is represented as a voltage source connected between ground and one side of 1 amp fast blow fuse 16, which in turn is connected to one side of ON-OFF switch 13. As depicted in FIG. 9, when the ON-OFF switch is in the ON position, the battery will provide a positive voltage through resistor 18 to light emitting diode 14 and to ground, energizing the light emitting diode. In addition, the same positive voltage will be connected to node 22, to power circuitry to be described. 
     With voltage applied to node 22, infrared LEDs 20 and 20&#39; (CR1 and CR2) are energized. To be more specific, voltage flows via current limiting resistor 19 through infrared LEDs 20 and 20&#39; to ground, energizing them. The resulting electro-optical radiation will pass by the sides of pendulum 34 to their associated photodarlington transistors 21 and 21&#39;. 
     When the recreation vehicle to which the the sensor unit is mounted is in in a level condition, the compound pendulum 34 is in a pendulum null condition. In this null condition, electrooptical infrared emission produced by light emitting diodes 20 and 20&#39; is allowed to pass along either side of the pendulum. The result is that photodarlington transistors 21 and 21&#39; will enable current to flow through current limiting resistors 29 and 26 and to ground, bypassing light emitting diodes 30 and 27. LEDs 30 and 27 are therefore not energized. Since current is not flowing to node 43 from either diode 31 or 32, darlington transistor 24, acting as an electronic switch is, &#34;OFF.&#34; Therefore, all the current flowing through resistor 23 passes through light emitting diode 25, energizing it, indicating a level condition for the recreation vehicle. 
     As shown in FIGS. 5-6, when the right side of the recreation vehicle upon which the sensor unit is mounted, is lower than desired, the compound pendulum 34 will swing to the right, obliterating the path of the infrared electro-optical emission going from infrared emitting LED 20&#39; to associated photodarlington transistor 21&#39;. The result will be that current will discontinue to flow through photodarlington transistor 21&#39;, via current limiting resistor 26. At the same time, a small portion of the current flow through resistor 26 will flow through diode 28 to node 43. The application of voltage to node 43 will cause current to flow, via resistor 32, through darlington transistor 24, switching it, &#34;ON.&#34; With darlington transistor 24 switched, &#34;ON,&#34; current normally flowing through LED 25, via resistor 23, to ground will now be flowing through darlington transistor 24 to ground via resistor 23. Therefore, LED 25 will no longer remain energized. 
     Similarly, one can apply the same logic when analyzing the response of the other, &#34;half,&#34; of the circuit, when the recreation vehicle is lower on the left side, the imbalance causes the pendulum 34 to swing to the left obliterating the path of infrared electro-optical emission from in between infrared emitting LED 20 and photodarlington transistor 21, causing indicator 30 to energize and indicator LED 25 to de-energize. 
     It should be noted that the design of the circuit precludes the ambiguous condition of having more than one illuminated light emitting diode. If either light emitting diode 28 or 30 is illuminated, a portion of the current flows to node 43 causing darlington transistor 24 to switch, &#34;ON.&#34; When darlington transistor 24 is, &#34;ON,&#34; the current normally flowing through light emitting diode 25 now flows through darlington transistor 24 to ground. Therefore, the possibility of simultaneous illumination of multiple light emitting diodes is eliminated. 
     In this particular embodiment of the circuitry, the following electronic components were selected: 
     
         ______________________________________   B+       Voltage 12 volts (from tow vehicle)Fuse    F1       one amp fast blow fuseLEDs    CR3      (amber)   CR4      (orange)   CR5      (green)Photon  CR1/Q1   GE H22B1Coupled CR2/Q2   GE H22B1InterrupterModulesResistors   R1       Carbon composition 250 ohms +/- 5%   R2       Carbon composition 470 ohms +/- 5%   R3       Carbon composition 470 ohms +/- 5%   R4       Carbon composition 470 ohms +/- 5%   R5       Carbon compositlon 1.3K ohms +/- 5%   R6       Carbon composition 510 ohms +/- 5%Diodes  D1       1N4007   D2       1N4007Darlington   Q3       MPS A13Transistor______________________________________