Abstract:
A pressure-regulating valve particularly useful in a diesel internal combustion engine with a closed crankcase is provided. The valve includes a body coupled to a bonnet with an internal movable piston. The movable piston maintains a substantially constant pressure in the crankcase by adjusting a fluid flow in response to changes in pressure. The movable piston also includes an integral relief valve to prevent overpressure in the event of a crankcase pressure in excess of the designed limits of the pressure-regulating valve.

Description:
This is a divisional of application Ser. No. 09/866,515, filed May 25, 2001, which is incorporated herein by reference in its entirety and which claims priority to provisional application Ser. No. 60/207,079 filed May 25, 2000. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to engine valve apparatus and, more particularly, to a pressure regulating piston valve with a built in relief valve. 
     BACKGROUND OF THE INVENTION 
     As engine manufacturers reduce exhaust emissions, crankcase blow-by vented to the atmosphere has become a larger contributor to the total emissions. Crankcase blow-by is produced when combustion gases, under high pressure, become contaminated with oil mist when blown past the piston rings into the crankcase. To further reduce the total emissions of engines, it has become necessary to rout these gases into the air intake system. In a closed system, this contaminated blow-by is ingested by the engine intake system. 
     Interest in closed crankcases is being driven both by regulatory as well as operating concerns. As of Jan. 1, 1998, the U.S. Environmental Protection Agency (EPA) required that all gaseous-fueled on-highway engines must have a closed crankcase. While there are as yet no specific regulations on closing the crankcases of diesel engines, the overall drive to reduce emissions has made most engine and equipment manufacturers become more interested in closing their crankcases. 
     In a closed crankcase system, crankcase blow-by gases, which inherently cause a rise in crankcase pressure, need to be routed back into the engine intake system. Excessive variations in crankcase pressure can damage seals and cause a loss of oil. There is a perceived need for a pressure regulator to minimize variation in crankcase pressure. There is also a perceived need for a relief valve to protect against overpressure in the crankcase that cannot be compensated for by the regulator itself. 
     The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention provides a pressure-regulating valve, including a body, a movable piston, and a relief valve. The body has a fluid passageway therethrough. The movable piston is disposed within the body and is movable in response to pressures thereon to adjust a fluid flow through the fluid passageway. The relief valve is integral to the piston. At least one hole in the piston is exposed to a relief passageway upon the application of a predetermined level of pressure on the piston. 
     Another aspect of the present invention provides a pressure-regulating valve, including an upper body portion, a lower body portion, a movable piston and a spool. The upper body portion is in fluid communication with a crankcase. The lower body portion isolated fluidly from the upper body portion and having a lower body fluid passageway therethrough in communication with a crankcase and a vacuum source. The movable piston is disposed within the upper body portion. The piston is movable in response to pressure thereon to adjust a fluid flow through the lower body fluid passageway. The spool connected to the piston and extending through the upper body portion and to the lower body portion. 
     Yet another aspect of the present invention provides a method of regulating pressure in a crankcase of an internal combustion engine. The method includes providing a crankcase valve responsive to crankcase pressure, wherein changes in crankcase pressure are communicated to the crankcase valve; adjusting a flow through the crankcase valve to correspondingly alter the crankcase pressure; and releasing overpressure in the crankcase through a relief valve integral to the crankcase valve upon application of a predetermined amount of pressure. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the invention disclosed herein, but merely to summarize the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing summary, preferred embodiments and other features or aspects of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 
     FIG. 1 is a cross-sectional view of a valve design in accordance with one aspect of the invention. 
     FIG. 2 is a top view of the design according to FIG.  1 . 
     FIG. 3 is a cross-sectional view of an alternative valve design according to one aspect of the invention. 
     FIG. 4 is a top view of the design according to FIG.  3 . 
     FIG. 5 is a top view of a valve piston in accordance with one aspect of the invention. 
     FIG. 6 is a cross-sectional view of the design according to FIG.  5 . 
     FIG. 7 is a detail of the circled area of FIG.  6 . 
     FIG. 8 is a cross-sectional view of a flow shaper design according to the invention. 
     FIG. 9 is a top view of the design according to FIG.  8 . 
     FIG. 10 is a side view of a plug in accordance with the invention. 
     FIG. 11 is a top view of a relief disc design in accordance with the invention. 
     FIG. 12 is a cross-sectional view of the relief disc shown in FIG.  11 . 
     FIG. 13 is a top view of a sealing disc design in accordance with the invention. 
     FIG. 14 is a side view of the sealing disc shown in FIG.  13 . 
     FIG. 15 is a cross-sectional view of a proportioning spool in accordance with the invention. 
     FIG. 16 is a cross-sectional view of an alternative embodiment for the valve in accordance with the invention. 
     FIG. 17 is a top view of the valve shown in FIG.  16 . 
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. The figures and written description are not intended to limit the breadth or scope of the invention in any manner, rather they are provided to illustrate the invention to a person of ordinary skill in the art by reference to particular embodiments of the invention, as required by 35 USC §112. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the figures, and in particular to FIG. 1, a pressure-regulating valve  2  in accordance with one embodiment of the invention is disclosed. Pressure regulating valve  2  may be used in equipment including, but not limited to, gas engines, diesel engines, generator sets and other power equipment. As shown in FIG. 1, pressure-regulating valve  2  includes a body  4  with a fluid passageway  6  extending therethrough. Fluid passageway  6  may facilitate, for example, fluid communication between a crankcase (not shown) and a vacuum source (not shown). In the embodiment shown in FIG. 2, fluid passageway  6  exhibits an inlet  14  and an outlet  16  that are substantially normal to one another, but this is not necessarily so. In other embodiments discussed in more detail later in this disclosure the inlet  14  and outlet  16  are arranged parallel to one another. It will be understood by one of skill in the art with the benefit of this disclosure that inlet  14  and outlet  16  may be arranged in any convenient manner. In the embodiment of FIG. 1, use of pressure regulating valve  2  is integrated into a diesel engine (not shown) with a closed crankcase to facilitate reduced emissions. 
     Attached to body  4  is a bonnet  8 . A diaphragm  10 , preferably a rolling diaphragm such as is available from Bellofram, Inc., is disposed between body  4  and bonnet  8 . Rolling diaphragm  10  fits into a groove  12  formed in body  4  and provides a gas-tight seal between body  4  and bonnet  8 . Bonnet  8  includes a relief flow passageway  13  isolated from fluid passageway  6  in normal operation. Relief flow passageway  13  may lead directly to atmosphere, or it may lead back to an engine intake manifold (not shown). 
     A movable piston assembly  18  is disposed inside body  4  and bonnet  8 . Piston assembly  18  includes a piston  20  that is also part of an integrated relief valve  22 . Piston  20  includes at least one hole, for example the six holes  52  equally spaced around the circumference of the piston as shown in FIG.  5 . Piston  20  includes at least one guide/stop leg, for example the four guides/stops  21  equally spaced around the circumference of the piston as shown in FIG. 5, to guide piston  20  inside bonnet  8  and to stop piston travel on angled wall  62  of bonnet  8 . Piston  20  is shown in some detail in FIGS. 5-7. Piston assembly  18  may also include a flow shaper  24  attached to a nipple  26  of piston  20 . Flow shaper  24  is shown in some detail on FIGS. 8 and 9. Flow shaper  24  may have a generally U-shaped cross-section and facilitates less turbulent flow through fluid passageway  6 . Opposite nipple  26  of piston  20  is a channel  28  receptive of a plug  30 . Plug  30  is shown in detail on FIG.  10  and includes a stem  32  with a raised portion(s)  34  to facilitate attachment to piston  20 . A head  36  of plug  30  retains a first end  38  of a biasing member, such as a conical spring  40 . Conical spring  40  exhibits a second end  42  that abuts relief disc  46 . Relief disk  46  is shown in detail in FIGS. 11 and 12 and includes a hole  48  to accommodate piston channel  28  and includes a groove  50  into which a second end  42  of conical spring  40  fits. Relief disk  46  may comprise, but it not limited to, Ryton R-4XT. 
     Between relief disk  46  and piston  20  is a sealing disk  44 . Sealing disk  44  is shown in FIGS. 13 and 14 and exhibits a hole  47  that also accommodates piston channel  28 . Sealing disk  44  may comprise, but is not limited to, a Buna-N copolymer with  40  durometer hardness. Sealing disk  44  is sandwiched between piston  20  and relief disk  46  by a force provided by conical spring  40 . Sealing disk  44  seals holes  52  in piston  20 . When a sufficient predetermined force is applied to sealing disk  44  from inside body  4 , the force of conical spring  40  may be overcome and allow for fluid communication between fluid passageway  6  and relief flow passageway  13 . 
     Body  4  exhibits opposing internal walls  54  and  56 , which are parts of fluid flow passageway  6 . First ends  58  and  60  of internal walls  54  and  56 , respectively, provide a limit to the travel of piston  20  within body  4 . In FIG. 1, piston  20  is in the full-open position with guide/stop legs  21  abutting angled wall  62  of bonnet  8 . Piston  20  may also travel between the position shown in FIG. 1 and a position in which the piston abuts ends  58  and  60 , closing off fluid communication between inlet  14  and outlet  16  of fluid flow passageway  6 . A biasing member, for example coiled compression spring  64  extending between piston  20  and body  4 , biases piston  20  to a open position as described above with guide/stop legs  21 E of piston  20  abutting angled wall  62  of bonnet  8 . Pressure, positive or negative, transmitted from, for example, the crankcase or vacuum source (not shown) may overcome the force supplied by coiled compression spring  64  to move piston  20  to the position shown in FIG. 1, or to any position in between the closed position and the full open position of FIG.  1 . Rolling diaphragm  10  seals the annulus between piston  20  and either bonnet  8  (in the full open position as shown in FIG. 1) or body  4  (in the closed position), or both bonnet  8  and body  4 . 
     The operation of pressure regulating valve  2  is described as follows. Pressure-regulating valve  2  may be positioned, for example, in a diesel engine comprising a closed crankcase (not shown). As the diesel engine runs some blow-by will occur and inherently cause the pressure in the closed crankcase to increase. It is desirable to keep the pressure in the crankcase regulated for reasons discussed in the background section. As the force on the piston  20  due to crankcase pressure and coiled compression spring  64  varies relative to the force on piston  20  due to the vacuum source, piston  20  travels advantageously toward either bonnet  8  or ends  58  and  60  of body  4 . When this occurs a gap  66  between ends  58  and  60  and piston  20  changes accordingly and regulates the flow past flow shaper  24  and through fluid passageway  6 , thus regulating the crankcase pressure. Thus, piston  20  adjusts itself relative to the forces applied to it, by crankcase pressure, vacuum source, and coiled compression spring  64 , to maintain a substantially constant pressure in the crankcase. In the event that the crankcase pressure exceeds the range under which pressure-regulating valve  2  is intended to operate, integral relief valve  22  opens, i.e. fluid communication between fluid flow passageway  6  and relief flow passageway  13  is established through holes  52  of piston  20 . The seal between holes  52  and sealing disk  44  breaks as pressure on the piston increases sufficiently to overcome the force on relief disk  46  provided by conical spring  40 . 
     A second embodiment of the invention is similarly disclosed in FIGS. 3,  4  and  15 . In the embodiment shown in these figures, all of the components shown in FIG. 1 are included in pressure-regulating valve  102 , however, this second embodiment includes some modifications. Body  104  of pressure-regulating valve  102  includes an upper portion  105  and a lower portion  103 . Lower portion  103  includes a fluid passageway  106  with an inlet  114  and outlet  116  substantially parallel to one another. Fluid passageway  106  may facilitate, for example, fluid communication between a crankcase (not shown) and a vacuum source (not shown). It will be understood by one of skill in the art with the benefit of this disclosure that the arrangement of the inlet and outlet may, be adjusted as necessary to fit within the engine parameters. Upper portion  105  includes a fluid passageway  107  with an inlet  109 . Inlet  109  may facilitate, for example, fluid communication between a crankcase and fluid passageway  107 . A flow shaper  124  is included in lower body  103  to reduce turbulent flow characteristics. In the embodiment shown in FIG. 3, flow shaper  124  is generally U-shaped, but it may also be straight or otherwise adjusted. There is no need for an additional flow shaper to be added to piston  120 . This absence of an additional flow shaper can be tolerated because in the embodiment shown in FIGS. 3,  4 , and  15 , there is no fluid communication between the upper portion  105  and the lower portion  103 , as there may be for the embodiment shown in FIG.  1 . In this embodiment, proportioning spool  170  in the lower body  103 , may take the place of flow shaper  24  of valve  2  shown in FIG.  1 . 
     Pressure regulating valve  102  as shown in FIG. 3 also includes a proportioning spool  170  that attaches at a first end  172  to piston  120  and extends through upper body  105  and into lower body  103 , where it passes through flow orifices  11  and  115  which separate inlet  114  from outlet  116 . As proportioning spool  170  travels with piston assembly  118 , the flow orifices  111  and  115  open and close. Proportioning spool  170  is shown in detail in FIG.  15  and includes a stem  182  with a groove  184  to facilitate attachment of first end  172  to piston  120 . The main body  186  of proportioning spool  170  may exhibit a slot or slots  188  to reduce mass. In some embodiments, there are four fins  189  that keep wall thickness uniform for molding and thus reduce the mass of proportioning spool  170 . Main body  186  may exhibit a channel  180  to allow fluid communication between inlet  114  and outlet  116  and to connect the tapered areas  191  and  193  of the proportioning spool  170 . Proportioning spool  170  may exhibit tapered areas  191  and  193  to regulate the amount of flow passing through orifices  111  and  115 . 
     Referring again to FIG. 3, an O-ring  174  held in place by an O-ring retainer  176  seals the annulus between proportioning spool  170  and upper body  105 . A gap  166  between a second end  178  of proportioning spool  170  and a flow orifice  111  disposed in lower body  103  allows for maximum fluid flow through fluid passageway  106  in the full open position shown in FIG.  3 . Coiled compression spring  104  biases piston  120  and thus of proportioning spool  170  to the open position shown with tapered areas  191  and  193  of proportioning spool  170  in a position which allows maximum fluid flow through flow orifices  111  and  115  and thus passageway  106 . 
     The piston  120 , diaphragm  110 , relief valve assembly  122  and other components of pressure regulating valve  102  are identical to the corresponding components described for pressure regulating valve  2 . 
     Operation of pressure regulating valve  102  is as follows. During engine operation, as crankcase and vacuum source pressure varies, the force on piston  120  correspondingly varies, this varying force is balanced by coiled compression spring  104  which exerts a force equal in magnitude but opposite in direction to the force created by the crankcase and vacuum source pressure. As this occurs, piston  120  and proportioning spool  170  which is rigidly attached thereto advantageously position to increase or decrease the flow orifice  111  and  115  areas, thus increasing or decreasing the fluid flow through fluid flow passageway  106 . The increased or decreased flow through fluid passageway  106  results in a regulated crankcase pressure. Piston  120  and thus proportioning spool  170  will self-adjust according to crankcase pressure, vacuum source pressure and the force supplied by coiled compression spring  164  to maintain a substantially constant pressure in the crankcase. In the event of crankcase pressure exceeding the range pressure regulating valve  102  is intended to operate under, integral relief valve assembly  122  advantageously opens, i.e. fluid communication between fluid flow passageway  107  and relief flow passageway  113  is established through holes  152  of piston  120 . The seal between holes  152  and sealing disk  144  breaks as pressure on the piston increases sufficiently to overcome the force on relief disk  146  provided by conical spring  140 . 
     In an alternative embodiment shown in FIGS. 16-17, piston  220  does not include a separate insertable plug or flow shaper but instead comprises a single piece. Piston  220  includes a head  221  at first end  238  where it meets conical spring  240  and an integral flow shaper  224  at second end  205 . This alternative embodiment does not include the optional flow shapers of the other embodiments, but otherwise, the components, including the operation of relief valve  222 , are identical to the embodiment shown in FIG.  1 . 
     In some applications, the pressures at which pistons  20 ,  120 , and  220  are operable are as follows. Pistons  20 ,  120 , and  220  may be biased in the open positions shown in the figures at atmospheric pressure, and may close proportionally at a pressure differential of approximately two to 10 inches of water. As crankcase pressure tends to increase, pistons  20 / 120 / 220  will open until the full open position (shown) is reached at a pressure of approximately ten inches of water. At any pressures greater than ten inches of water, relief valves  22 / 122 / 222  open and release the excess crankcase pressure. It will be understood by one of skill in the art with the benefit of this disclosure, however, that these pressure ranges are only exemplary, and that the springs and valves may be designed to meet any other pressure ranges as necessary. 
     While the present invention has been particularly shown and described with reference to a particular illustrative embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention. The above-described embodiment is intended to be merely illustrative, and should not be considered as limiting the scope of the present invention.