Abstract:
This invention consists of a Level Sensing Device and Hydraulic Control Valve, which, when, as a team, is applied to a system with a Hydraulic Pump W/Oil Reservoir, three or four Hydraulic Jacks, three or four Normally-Open Solenoid-Operated In-Line Hydraulic Valves, and piped and wired as described in this document, will provide a completely automatic leveling system for Recreational Vehicles, such as, Motorhomes, Pick-up Campers, and Camping Trailers. This Leveling Sensor/Switch and Hydraulic Control Valve can also be retro-fit into any exsisting manually-operated or semi-automatic hydraulic leveling system and, as a team, make it a completely automatic leveling system.

Description:
BACKGROUND AND SUMMARY 
   There are many Leveling Systems for land vehicles of the recreational type, such as, RV&#39;s, Pick-up Campers, and Camper trailers, and such. They are all mainly comprised of: 
   (a) A medium, such as, Air, or Hydraulic Fluid to provide the elevating forces that are pumped to Jacks. 
   (b) In the case of the Hydraulic System, a Hydraulic Pump W/Reservoir from which to pump the fluid to a plurality of three or four Jacks, thus extending the Jacks, and to receive and store that same fluid from the Jacks when the Jacks are being retracted. 
   (c) A plurality of three or four Hydraulic Jacks placed strategically on the vehicle in such a way as to raise the various vehicle points to attain a level attitude of the vehicle. 
   (d) A piping system to provide the delivery of the fluid from the Pump to the Jacks. 
   (e) A sensing device to sense the relative out-of-level condition of the vehicle to the ground and send signals to the Pump and Jacks to effect a level attitude of the vehicle. 
   It is not the Inventor&#39;s intent to reinvent the leveling systems as we presently know them, but to add a choice to the installer and the customer of a Leveling Sensor and Controller which is completely automatic, simple to operate, and is essentially maintenance-free. To that extent this Invention focuses on the elements (d) and (e) of the previous paragraph. It consists of a LEVEL SENSOR/SWITCH that senses the out-of-level relationship of the vehicle to that of the ground on which it is parked. The LEVEL SENSOR/SWITCH then sends electrical signals to the In-line Solenoid-operated Hydraulic Valves in the piping lines to the various Jacks. These signals will control the fluid delivery “on” and “off” to the various Jacks as required to extend the Jacks to achieve a level attitude of the vehicle. 
   The HYDRAULIC CONTROL VALVE provides the means of delivering fluid to the upper chambers of the Jacks when wanting to raise or level the vehicle, and, in the case of double-acting Jacks, to allow the fluid in the lower chambers of the Jacks to return to the Oil Reservoir. Also, in the case of double-acting Jacks, it provides the means of delivering fluid to the lower chambers of the Jacks when wanting to lower the vehicle by retracting the Jacks. It also, then, allows the fluid in the upper chambers of the Jacks to return to the Oil Reservoir. 

   
     BRIEF DESCRIPTION OF THE DRAWING SHEETS 
     FIG.  1 : Shows the SENSOR/SWITCH ASS&#39;Y. (Also see  FIG. 7  drawing sheet). It is essentially a glass vial with a spherical floor upon which floats a pool of Liquid Mercury. There is an electrical conductor at the center and is always immersed in the pool of Mercury, regardless of the tilt of the unit. Around the center conductor is a circle of five electrodes placed as shown, and all are barely in contact with the Mercury when the unit is in a level attitude. Thus, in any condition of tilt of the unit, some electrodes will be in contact with the Mercury and some will not. The markings, RR, LR, RF, LF, and CF indicate which Jack position the electrode controls. The marking, FRONT, indicates the relative position of direction in the vehicle. 
     FIG.  2 : Shows the Control Valve Ass&#39;y. with its control lever for selecting the mode for leveling and/or raising the vehicle, or its mode for retracting the Jacks to their “UP” position. Mini-Micro Switch, Pt.#  216 - 1 , provides electric current to the Hydraulic Pump and the Sensor/Switch Ass&#39;y. Mini-Micro Switch, Pt.#  216 - 2 , provides electric current to the Hydraulic Pump only. 
     FIG.  3 : Shows the Piping and Wiring requirements of the Sensor/Switch Ass&#39;y, the Hydraulic Control Valve Ass&#39;y., and the In-line Solenoid-Operated Hydraulic Valves for a 4-Jack system with instructions for the use of double-acting Jacks and for single-acting Jacks with spring return. 
     FIG.  4 : Shows the Piping and Wiring requirements of a 3-Jack system. Includes instructions for use of double-acting Jacks and single-acting Jacks with spring return. 
     FIGS.  5  &amp;  6 : Shows the electrical circuits that will provide a completely automatic operation for the 4-Jack systems and the 3-Jack systems, respectively. 
       FIGS. 7 ,  7 A,  7 B, &amp;  7 C: Shows all the shape and dimensional criteria necessary to manufacture the Leveling Sensor/Switch Ass&#39;y. 100-Series Part Numbers have been assigned in order to identify all the details, and notes have been added to direct the manufacturing of the Ass&#39;y, and help to give a clear picture and understanding of their functions. 
       FIGS. 8 , &amp;  8 A thru  8 F: Shows all the shape and dimensional criteria necessary to manufacture the Hydraulic Control Valve Ass&#39;y. 200-Series Part Numbers have been assigned in order to identify all the details, and notes have been added to direct the manufacturing of the Ass&#39;y. and help to give a clear picture and understanding of their functions. 
     FIG.  9 : Shows a concept of how the components can be packaged and to the simplicity of required panel instrumentation. It also suggests the addition of a Spot Level and Delta Note 1, which suggests marking the Spot Level to give the customer a visional refence on the maximum tilt allowable for all Jacks to reach the ground. This would eliminate a lot of possible trial and error to achieve a successful leveling with all Jacks on the ground. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Fluid transfer from the Oil Reservoir &amp; Pump to the Jacks &amp; return is provided by the Hydraulic Control Valve, Pt.#  200  (See  FIG. 8 , etc.). To help explain the paths of fluid flow and the function of the Control Valve, all holes on the Control Valve Body, Pt.#  201 , are identified by a bold numeral. Direction of fluid flow is accomplished thru (8) Ball-check Valves located in Hole No&#39;s.  1  thru  8  as shown in  FIG. 8A , and comprised of Pt.#s  203  thru  208  as shown in Section E-E′, on FIG.  8 C. These Ball Checks have a fluid hole below the spring-loaded Ball &amp; Seat and a fluid hole above the Ball &amp; Seat. Fluid introduced thru the upper hole and on to the Ball can overcome the spring pressure against the Ball and continue on to the lower hole. Fluid introduced thru the lower hole is stopped by the spring-loaded Ball against the seat unless the Ball is depressed by Pt.#  203  (See FIG.  8 C), allowing fluid to flow thru to the upper hole. Selective depressing of the Balls at these (8) Ball Checks controls the oil flow to the chambers of the Jacks and allows the oil from the opposite chambers of the Jacks to return the Oil Reservoir. 
   The Ball-Check Valves are depressed by either of (2) Plates, Pt.#s.  211  &amp;  212  (See FIG.  8 E). Pt.#  211  Plate is positioned over the Ball-Check Valves in holes  1  &amp;  2 . Pt.#  212  Plate is positioned over the Ball-Check Valves in holes  3 ,  4 ,  5 ,  6 ,  7 , &amp;  8  (See FIGS.  8  &amp;  8 A). the depressing of these Plates is accomplished by a sub-assembly of parts as shown on FIG.  8  and is comprised of the following parts: Pt.#  213  Bracket, Pt.#  214  Cam with (2) Pt.#  214 - 1  Rivets, (2) Pt.#  214 - 2  Steel Pins, (2) Pt.#  214 - 3  Ball Bearings, Pt.#s  215  &amp;  215 - 1  Cam Handle, (1) ea. Pt.#s  216 - 1  &amp;  216 - 2  Mini-Microswitches, (1) Pt.#  217  Steel Pin, and (1) Pt.#  218  Cotter Pin. (See  FIGS. 8E &amp; 8F  for detailed drawings of these parts, and  FIG. 8  for the Ass&#39;y.). 
   When the Cam Handle is in the RAISE/LEVEL position, (See FIG.  2  &amp; FIG.  8 .), a button on the Cam, Pt.#  214 - 1 , will have rotated into position to depress Mini-Microswitch Pt.#  216 - 1 , supplying electric current to the Hydraulic Pump and the Sensor/Switch Ass&#39;y. At the same time the Ball Bearing, Pt.#  214 - 3 , will have rotated into position to depress Plate, Pt.#  211  , which in turn depresses the Ball Valves in holes  1  &amp;  2 . Next, see SECTION B-B′,  FIGS. 8A &amp; 8C . Oil from the Pump enters port at hole  18 , and with Ball Valve in hole  1  being depressed, oil is allowed past the Ball and enters hole  30 . It continues on to hole  29 . Hole  29  connects holes  5 ,  6 ,  7 , &amp;  8 , above the Ball Checks, (See FIG.  8 A), so oil pressure will overcome spring pressure against the Balls and pass on to Ports  13 ,  14 ,  15 , &amp;  16  and on to the upper chambers of the Jacks. Note that since the Balls are not depressed, oil cannot flow back. This arrangement makes each Jack independent of the others. Note, also, on  FIG. 8A , that Ports  9 ,  10 ,  11 , &amp;  12  are interconnected by holes  23  &amp;  24 . These Ports are the ones supplying oil to the lower Jack chambers in order to retract the Jacks if using double-acting Jacks. If using single-acting Jacks with spring return, these ports are not used and must be plugged. Also, when the Cam Handle is in the RAISE/LEVEL position and oil pressure is extending the Jacks, the oil pressure in the Lower Chambers of the double-acting Jacks must be relieved. So while in this mode and the Ball Valve in hole  2  being depressed, oil from the lower Jack chambers will return thru Ports  9 ,  10 ,  11 , &amp;  12  (See  FIGS. 8A &amp; 8C , Sect. D-D′) thru holes  23  &amp;  24 , to hole  22 , to hole  20 , to hole  25 , and entering hole  2  below the Ball, but with the Ball Valve being depressed, the oil is allowed past the Ball and out Port  19  and returned to the oil reservoir. 
   With the Cam Handle, Pt.#  215 , in the RETRACT position (See FIG.  2  &amp; FIG.  8 ), a Button, (Pt.#  214 - 1 ), will have rotated into position to depress Mini-Microswitch, Pt.#  216 - 2 , supplying electric current to the Hydraulic Pump only. At the same time, Ball Bearing, Pt.#  214 - 3 , will have rotated into position to depress Plate, Pt.#  212 , which, in turn, depresses the Ball Valves in holes  3 ,  4 ,  5 ,  6 ,  7 , &amp;  8 , (See Sect. C-C′, FIGS.  8 A &amp;  8 C). oil from pump enters at Port  18  (Sect. B-B′), and since Ball Valve in hole  1  is not depressed, oil will flow thru hole  27  to hole  26  to Ball Valve in hole  4 . With Ball Valve in hole  4  now being depressed, oil is allowed past Ball to hole  22  to holes  23  &amp;  24  and enter Ports  9 ,  10 ,  11 ,  12 , which are the Ports to the Lower Chambers of the Jacks, thus retracting the Jacks. Since the Ball Valves in holes  5 ,  6 ,  7 , &amp;  8  are now depressed, oil can flow back past the Balls to hole  29  (See Section B-B′) to hole  30 , to hole  21 , down to hole  28 , and enter hole  3  below the Ball (See Section A-A′). With Ball Valve in hole  3  depressed, oil will go past the Ball and return to the oil reservoir thru Port  17 . 
   The SENSOR/SWITCH ASS&#39;Y, Pt.#  100 , (See  FIG. 7 ) shows the device to be essentially a Glass Vacuum Envelope. The bottom half of the Envelope, Pt.#  101 , has a spherical-radius floor upon which the Liquid Mercury, Pt.#  109 , will float. A conductor, Pt.#  106 , located on the vertical center-line, is connected to an electrical source. It extends to the floor and thus is always in contact with the Mercury, regardless of the tilt of the device. This Center Conductor is surrounded by (5) Electrodes, Pt.#  107 . Note that the final adjustments of these Electrodes relative to the surface of the Mercury puddle must be made per Delta Note 4 and while the unit is in a level position. And so with all electrodes in contact with the Mercury and current flowing thru the Mercury, a signal will go to all the Normally Open S.O. Valves to close and stop oil flow to the Jacks. Thus, as the unit begins to tilt, the Mercury puddle will glide away from certain Electrodes, depending on the direction of tilt and the opposite Electrodes will be immersed in the Mercury and cause electric current to flow from the Center conductor to the immersed Electrodes, and send a signal to the pertinent S.O. Valves to close and stop oil flow to those Jacks. Conversely, the Electrodes that are not in contact with the Mercury will have no current flowing to their respective S.O. Valves, allowing oil to flow to those Jacks. Also note that the markings at each Electrode on the Sensor/Switch Ass&#39;y. is 180 degrees from its relative position with respect to the front of the vehicle, and the markings denote the respective Solenoid-Operated In-line Hydraulic Valve to which that Electrode is to be connected. Hence, the wire from the Electrode at the left front of the Sensor/Switch and marked RR(Right Rear) should be connected to the S.O. Valve in the oil line to the Right Rear Jack on the vehicle. The RF Electrode is connected to the S.O. Valve in the oil line of the Right Front Jack of the vehicle, and so on and so forth.(See FIGS.  3  &amp;  4 ). 
   Two Switch components in the circuitry not yet addressed are the Adjustable HydraulicPressure Limit Switch, Pt.#  219  (See  FIGS. 5 &amp; 6 , and  FIG. 8 , Note delta 2), and the “JOG TO RAISE” Switch, Pt.#  110  (See  FIGS. 5 &amp; 6 , and  FIG. 7  Bill of Material). The Hyd. Pressure Limit Switch, Pt.#  219 , should be set to interrupt the electric current at a slightly higher line pressure than required to lift the entire vehicle. It is installed in the hydraulic in-put supply line somewhere before entering the Hydraulic Control Valve, Pt.#  200 . Its purpose is to provide the automatic feature of the leveling system by cutting off electric current to the Hydraulic Pump after the vehicle reaches the level attitude and all S.O. Valves are in Stop Mode. The purpose of the “JOG TO RAISE” switch is to override the automatic level feature when wanting to continue raising the vehicle after reaching the level attitude. It is a normally closed momentary switch. Holding the button down stops the electric current to the S.O. Hyd. In-line Valves, allowing fluid flow on to the Jacks, such as, in the case of a pick-up camper to raise the camper from the ground and place it on the pick-up bed and to remove it when desired. Another use of the “JOG TO RAISE” switch is to assure that all Jacks reach the ground in a 4-Jack system. Starting from an out of level condition, the Jacks at the low end of the vehicle will start extending, while the Jacks at the high end may never receive a signal to extend before the vehicle reaches level and the system shuts down. If all Jacks have not reached the ground when the vehicle reaches level and automatically shuts down, the lack of current to the S.O. Valves will open these valves. This will cause a line pressure relievement to the unextended Jacks and consequently restart the Pump and close the S.O. Valves, again building up excessive line pressure and again shutting down,etc. At this time, the Operator should depress and hold the “JOG TO RAISE” button, which will cut off current to the S.O. Valves, opening them all to flow. The current to the Pump will remain ON and oil will flow to the lines of the least resistance, namely, to the unextended Jacks. The Operator should continue to keep the “JOG TO RAISE” switch depressed until he sees the vehicle start to lose level. At this time, He can release the button and the automatic system will take over and relevel the vehicle and shut down, this time with all Jacks firmly on the ground. The Operator can then return the Cam Handle to the central position and switch the system power to OFF. Or, if he chooses, he can leave the Cam Handle in the RAISE/LEVEL position and the System will remain in “Sleep” Mode. If the vehicle should for any reason fall out of level, the System will “Awaken” to relevel the vehicle and shut down. And so on into the night.