Abstract:
A vehicle leveling valve for flowing pressured air to an airbag when its height falls below a predetermined height at the bottom of a height range, and for flowing air out of the airbag when its height rises above the top of the height range, which enables easy adjustment. A main valve member has a sealing surface ( 36 ) with a slot ( 34 ) therein. A disc ( 30 ) that pivots as the airbag height changes, has bores ( 122 ) that hold inserts ( 42, 46 ) with passages ( 40, 44 ). The inserts are biased against the sealing surface and have passage near ends ( 150 ) that lie adjacent to the slot ends. Each insert can pivot about a pivot axis within a disc bore ( 122 ), and each passage near end has a center ( 130 ) that is offset from the pivot axis ( 132   a ). Each insert can be pivoted about the pivot axis to shift the passage end slightly closer or further from the slot end ( 102 ) to adjust the top or bottom of the height zone.

Description:
CROSS-REFERENCE  
       [0001]    Applicant claims priority from U.S. Provisional Patent Application Serial No. 60/454,225 filed Mar. 12, 2003. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Airbags are commonly used in large vehicles, as to support a vehicle cab on a chassis and to support a trailer on a frame, the airbags absorbing road shocks. A vehicle manufacturer commonly sets a predetermined optimum height for the airbag. An airbag valve, commonly referred to as a leveling valve, maintains a height close to the predetermined height. It does this by flowing air from a pressured air source to the airbag when the height falls below a predetermined height such as 5 inches for a cab airbag and 15 inches for a tractor airbag, and flowing air from the airbag into the atmosphere when the height has increased. A height zone, such as from 14.9 inches to 15.1 inches may be established within which there is no air flow into or out of the airbag. The pressured air source is commonly set at a pressure of perhaps 130 psi, and is used to operate brakes, a horn, a pneumatic seat, and other miscellaneous equipment on the vehicle. The optimum pressure of the airbag may be about 40 psi to 70 psi, the pressure varying with the load.  
           [0003]    One type of leveling valve in widespread use is mounted on a vehicle frame and includes a disc that can pivot back and fourth as a handle inner end attached to the disc moves up and down, the handle outer end moving up and down with a vehicle axle. The disc carries inserts that are pressed tightly against a sealing surface of a main valve member that has a slot. As the disc pivots clockwise and counterclockwise, passages in the inserts move over ends of the slots to complete air paths that flow air into or out of the airbag. This type of airbag valve is described in U.S. Pat. Nos. 5,934,320 and 6,202,992.  
           [0004]    When the disc is in its neutral position, the airbag height should be at the predetermined height (e.g. 15.0 inches). It is usually desirable that the disc pivot only a small angle such as 1.5° before the airbag is connected to one insert passage that leads to the pressured air or is connected to the other insert passage that leads to a dump (the environment). In one example, the valve handle is 8 inches long, the insert passages lie one-half inch from the disc axis, and the air is supposed to flow when the airbag height changes by about one-eighth inch. The valve parts must be maintained within close tolerances to assure that the air valve slot will not be connected to either insert passage until the disc is pivoted 1.5° in either direction from the initial, or neutral position. Accumulated tolerances in each of several different parts contribute to variations in the required disc pivot angles to connect the airbag to the pressured air source or the dump. If the accumulated tolerances are great enough, there can be a worst case scenario wherein the slot is simultaneously connected to both the pressured air source and the dump, causing continual leakage of air from the pressure source into the environment. To prevent this, the valve parts are made with high precision, resulting in increased cost; also, a greater angle than the optimum of perhaps 1.5° is often resorted to. It is noted that the pivoting of the valve in either direction before it begins a connection to the high pressure source or to the environment, is called the “dead zone” wherein no air flows into or out of the airbag.  
         SUMMARY OF THE INVENTION  
         [0005]    In accordance with one embodiment of the invention, a vehicle leveling valve is provided, of the type that has a moveable member such as a disc, with bores that receive inserts with passages and with insert near ends that are biased against a sealing surface of a stationary valve member. When the moveable member moves, the insert near ends move over a slot in the sealing surface to allow air to flow into or out of an airbag. The present invention provides a simple and low cost way to adjust the dead zone along which the moveable member moves. Each insert is pivotable about a pivot axis within a corresponding bore in the moveable member, and each insert passage near end is offset from the corresponding pivot axis. As a result, each insert can be turned to shift the passage near end toward or away from the slot. Each slot has a slot end lying adjacent to an insert passage, the slot end being primarily straight and extending primarily circumferential to the adjacent insert pivot axis.  
           [0006]    Each bore holds an adjuster that has a far end that can be turned by a wrench or other turning tool to turn the corresponding insert. A spring in each moveable member bore biases the insert near end firmly against the sealing surface, and biases the adjuster against an internal flange at the far end of the bore. Each adjuster has a narrow blade that passes through the spring and engages a slot in the insert to turn the insert. The blade occupies less that half the cross-sectional area within the insert passage to allow air to flow through the passage.  
           [0007]    The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is an isometric view of a leveling valve constructed in accordance with one embodiment of the invention.  
         [0009]    [0009]FIG. 2 is a sectional view of the valve of FIG. 1.  
         [0010]    [0010]FIG. 2A is a partial sectional view taken on line  2 A- 2 A of FIG. 2.  
         [0011]    [0011]FIG. 3 is an exploded isometric view taken from the bottom , or far end of the valve of the FIG. 1.  
         [0012]    [0012]FIG. 4 is an exploded isometric view similar to that of FIG. 3, but taken from the top, or near end of the valve, and without the valve top.  
         [0013]    [0013]FIG. 4A is an enlarged isometric view of one of the inserts of the valve of FIG. 4.  
         [0014]    [0014]FIG. 5 is a plan view of the sealing surface of a prior art leveling valve, and showing in phantom lines, two inserts in the disc moving member.  
         [0015]    [0015]FIG. 6 is a plan view of the sealing surface of the valve of FIG. 2, and showing in phantom lines, the two inserts of the disc.  
         [0016]    [0016]FIG. 7 is an enlarged view of a portion of the sealing surface and an insert, of FIG. 6, the insert being shown in phantom lines. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 illustrates an airbag valve assembly  10  of the present invention, which has a port  12  connected to a vehicle airbag, a port  14  that is connected to a pressured air source (e.g. 130 psi) and a port  16  that is connected to the environment and which is sometimes referred to as a dump through which air is disposed of. An actuator in the form of a handle  20  controls the valve. The actuator  20  can have an end  22  connected to one end of the airbag such as the lower end that is mounted on a vehicle axle, while the valve  24  is coupled to the opposite end of the airbag such as to a chassis that is supported by the airbag. As the chassis moves up and down, the handle  22  pivots a shaft  32  of the valve  24 , and operates the valve.  
         [0018]    [0018]FIG. 2 shows that the valve includes a moveable member in the form of a disc  30  that is fixed to the shaft  32  and that pivots with it about a disc axis  38 . The disc  30  has a sealing surface  36  with a slot  34  that can be connected to a passage  40  in a high pressure air insert  42 , or that can be connected to a passage  44  in a dump insert  46 . An area  50  above the disc is continually connected to the airbag.  
         [0019]    [0019]FIG. 3 shows that the disc  30  that is pivoted by the actuator handle, has an interrupted slot  34  with two slot portions  60 ,  62 . The inserts  42 ,  46  are pressed upwardly towards the disc by a pair of springs  64 ,  66 . A pair of adjusters  70 ,  72  have screwdriver-like blades  74 ,  76  that lie in corresponding slots  80 ,  82  of the inserts to turn them, for reasons that will be described later herein. Each adjuster has a tool receiver in the form of an hexagonal socket  78  for receiving a turning tool such as a hex wrench for turning it. FIG. 4 shows that the inserts  42 ,  46 , springs  64 ,  66 , and adjusters  70 ,  72  are received in bores  122  of the valve body  84  which is a stationary member. FIG. 3 shows a valve top  86  which lies over the valve body  84  and an O-ring  90  that forms a seal between them. Screws  92  (FIG. 1) clamp the valve top  86  to the valve body.  
         [0020]    [0020]FIG. 5 shows a portion of a prior art valve which is similar to the present valve. The prior art valve  100  includes a disc  30 A with an interrupted slot  34 A and a pair of valve inserts  42 A,  46 A with insert passages  40 A and  44 A. Ideally, proximal, ends  102 A,  104 A of the slot were positioned about the disc axis  38 A to lie at angles A, B from adjacent locations  110 A,  112 A of the insert passages, so each angle has a value such as 1.5° in the initial disc position illustrated in FIG. 5. Pivoting of the disc  30 A by 1.5° in the clockwise CW or counterclockwise CCW directions connected the airbag to the dump or to the high pressure source. There was a “dead band” (A+B) of ±1.5°, within which the disc could pivot without any connection of the slot  34 A to either insert passage.  
         [0021]    In practice, the actual position of the disc relative to the insert passages depends upon an accumulation of tolerances. In order to maintain the dead zone A+B very close to ±1.5°, requires very tight tolerances of parts, which increases the cost of manufacture of the air valve. Variations in the ideal angles A, B can be undesirable. Angles A, B appreciably greater than the ideal (e.g. 1.5°) may result in a constant airbag height considerably more or less than the optimum airbag height, resulting in a bumpy or otherwise poor ride. An angle A or B substantially less than optimum (e.g. 1.5°) may cause very frequent airbag filling or emptying which wastes pressured air and which may cause the airbag to remain at a height other than optimum. Even more harmful, one or both angles considerably less than 1.5° may even cause continual drain of pressured air through the valve to the atmosphere.  
         [0022]    [0022]FIG. 6 shows a portion of the airbag valve  10  of the present invention, wherein the inserts  42 ,  46  are constructed with passages  40 ,  44 , wherein at least the near end of each passage  40 ,  44  (the end that lies closest to the sealing surface  36 ) is offset from the centers of the cylindrical periphery  120  of the corresponding insert, and from the center of the cylindrical hole or bore  122  in which that insert lies. The offset distance G is small, but sufficient to enable adjustment of the dead band angles C, D. FIG. 7 shows that in an initial position of the insert  42 , the center  130  of the insert passage  40  (at least the top, or near part of it) is spaced from the center  132 . The insert center  132  is the center of the periphery or outside  120  of the insert, while the passage center  130  is the center of the periphery of the passage near end. The center  132  lies on a pivot axis  132   a  which extends normal (perpendicular) to the sealing surface and to the insert face. The spacing G is in a direction radial to the axis  38  of the shaft and disc (i.e. the spacing is along a radial line  134 ), and parallel to the primarily straight proximal end  102  of the disc slot. Accordingly, one-half of the dead band angle remains at the angle C. However, if the insert is turned 90° in a clockwise direction CW from the initial position, the adjacent location  110  (location closest to the slot end  102 ) of the insert passage moves from  110  to the position  110 X (a point on the passage moves from  111  to  110 X) wherein the passage extends beyond the proximal end  102  of the slot. Similarly, if the insert is rotated 90° in the counterclockwise direction CCW from the initial position, the proximal end  110  of the insert passage is moved to the position  110 Y (a point at  113  is moved to  110 Y) wherein the passage is spaced much further from the proximal end  102  of the disc slot. Applicant notes that the insert passage  40  has a diameter E (FIG. 6) that is a plurality of times the offset G, so substantially the full insert passage end is connected to the slot during the first fillup of the airbag.  
         [0023]    Applicant can construct the valve, so that in the initial position of the insert  42 , it lies in the initial position wherein its passage center  130  (FIG. 7) is spaced from the center  132  of the insert periphery, in a direction radial to the shaft axis  38 . The slot end  102  is primarily straight (a radius of curvature more than twice the width of the slot  34 ). Applicant then tests the valve to determine the required angle of the valve handle away from its initial position, required before high pressure air applied to the high pressure port ( 14  in FIG. 2) begins to flow into the airbag port  12  that is normally connected to the airbag. Applicant then turns the insert  42  until it lies at the desired angle from the initial handle position (e.g. 1.5°) before such connection of the high pressure port to the airbag port will begin to be made. For a given offset G and other dimensions, a predetermined large insert pivoting (about 45°) from the angle of beginning of leakage, can produce the desired 1.5° angle. A similar test and turning of the other valve insert  46  is performed so the dead band angles C, D of FIG. 6 are each at the desired angles. The adjustments of the valve inserts  42 ,  46  are made to select the center of the dead band. The center of the dead band can be set to coincide with the mechanical centerline of the valve (when the valve handle end  22  is at the desired height), but can be set to any desired position.  
         [0024]    In actuality, applicant prefers that in the initial position of the valve, with the airbag height halfway between the extremes (e.g. at 15.0 inches which is halfway between 14.9 inch and 15.1 inch positions at which air starts flowing), the center  130  of the passage lies at point K (FIG. 7) which is 45° from position  130 . Also, applicant may place stops that prevent insert pivoting more than predetermined angles such as ±45° from an initial position such as where the passage near end center lies at K.  
         [0025]    [0025]FIG. 3 shows that each insert such as  42  can be turned by a technician inserting a hex wrench into the hex socket  78  of a corresponding adjuster. The blade  74  of the adjuster lies in the slot  80  of the insert so turning of the adjuster causes turning of the insert. FIG. 2 shows that the adjuster hex socket  78  is accessible from the bottom (far end) of the valve, and can be used to turn the corresponding insert  42 . The figure also shows that the other insert  46  has a passage  44  with an insert passage near end  150  which is the only portion offset from the axis of the insert periphery. This has the advantage that most of the passage  44  is concentric with the disc bore  122 , so the walls of passage  44  are largely uniform and strong for a bore  122  and passage  44  of given diameters.  
         [0026]    [0026]FIG. 2 shows that each bore has a far end that forms an internal flange  160 . Each spring  64 ,  66  presses the corresponding adjuster  70 ,  72  with considerable force against the flange, and presses the face  162  of the corresponding insert with considerable force against the sealed surface, which prevents both the insert and the adjuster from turning unless forced to turn. Blades  74 ,  76  are used to connect a part of each adjuster to an insert. As shown in FIG. 2A, each blade such as  74  occupies less than half the cross-sectional area within the corresponding insert passage  42 . This allows air to flow rapidly through the passage, with minimum obstruction.  
         [0027]    In one valve that applicant has designed, the distance between the disc axis  38  (FIG. 7) and insert pivot axis  132  is 10.3 mm. The center  130  of each passage near end was offset a distance G of 0.25 mm from the insert pivot axis  132 . This results in a maximum change in angle C of ±1.5° from the neutral position of the center at  130 . Most of valve parts were of steel, but the inserts were of ceramic to reduce wear.  
         [0028]    [0028]FIG. 8 illustrates a modified adjuster  140  with a far end surface  142  that has adjuster projections  144 . The flange  160  in the far portion of the bore  152  of the main valve part has recesses  154  that each can receive one of the adjuster projections. To turn the adjuster, a person inserts a hex wrench into the hex socket  78 A and pushes upward with sufficient force to overcome the force of the spring. With the adjuster pushed upward, the wrench is turned, and is then released. The projections usually will fall into recesses (or can turn by only a small angle before falling into the recesses), which then prevents the adjuster from turning.  
         [0029]    In FIG. 8, applicant forms the projections  144  and recesses  154  in conical surfaces  142 ,  156  of the adjuster and bore walls, which helps center the adjuster in the bore. The projections and recesses extend toward the pivot axis  132 A. When the projections lie in the recesses, the downward, or far force of the adjuster conical surface  142  is supported by the conical surface  156  of the bore walls. The conical surfaces can be easily formed to provide wide area contact.  
         [0030]    In the arrangement shown in FIG. 8 that applicants have designed, the adjuster had six projections angled 60° apart about the axis  132 A. The tapered bore wall had seventy-two recesses  154  angled 5° apart. An angle between 5° and 20° is preferred, and any angle that can divide 360° and yield a whole number can be used.  
         [0031]    Although applicant has shown and described an insert-holding moving member in the form of a disc, it should be understood that other valve constructions can be used such as one with a linearly sliding moving member. However, the same principles of an insert passage that is offset from a pivot axis of a bore that receives the insert passage, can be applied.  
         [0032]    Thus, the invention provides an airbag valve with the dead band angles at opposite ends of the interrupted slot in the disc, being adjustable. This is accomplished by forming at least the near end of each insert passage which lies adjacent to the sealing surface, so the center of the passage near end is offset from the center of the periphery of the disc or other part about which the disc is rotatable. Each insert can be turned about its axis of pivoting, to adjust the corresponding dead band angle. This allows a precise setting of each dead band angle, while also allowing the airbag valve parts to be constructed with greater tolerances. The inserts and adjusters can be installed in prior art valves of the type illustrated in FIG. 5 as retrofits.  
         [0033]    Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.