Bypass flow pressure regulator

Abstract: A pressure regulating device regulates the pressure of a flowing medium and includes a stationary member. A movable armature is disposed axially from the stationary member for moving axially in relation to the stationary member. A coil is disposed about the stationary member and the armature and through which current flows for generating magnetic flux to create an attractive force to move the armature in relation to the stationary member. A housing is disposed about the coil and the stationary member and the armature for encasing the armature and the coil and the stationary member. At least one aperture is formed in the housing to allow a fluid medium to enter and exit the housing and to contact the armature. A means bleeds a portion of the fluid medium based on the current to the coil to control the output pressure to predetermined levels.

Description: The invention relates to a pressure regulating assembly as per the preamble of claim 1. A pressure regulating assembly of the said type is disclosed in US-A-4 579 145. This assembly comprises a housing which accomodates a magnetic coil and an armature, and a control slide actuated by the armature and movable within a valve through which pressure medium to be controlled passes. A plunger carrying the armature is arranged coaxially to the magnetic coil within the housing, and is supported at the both ends axially. A diaphragm spring is arranged at the end of the plunger facing toward to the control slide. A pin loaded with the control pressure and arranged at the end of the control slide acts on the control slide. US-A-3 073 345 discloses a vacuum regulator comprising a casing with a solenoid armature and a coil attached thereto; the casing has a vacuum supply inlet and a modulated vacuum outlet defining three chambers. There is a spring loaded diaphragm which separates the first chamber from the third chamber and which carries a valve controlling the inlet and the outlet. A problem with some of these pressure control devices is that they are not resistant to contamination, which compromises their reliability. Another problem is that such devices are single-stage devices wherein a spool valve is in direct contact with (and moved by) the armature, which requires that the position of the spool must be indexed to that of the armature, which complicates the device. Also, the travel of the spool is limited by what the armature can accommodate. Still further, only magnetic forces are available to move the spool. A main object of the invention is to provide a pressure control device that overcomes problems, such as those referred to above, exhibited by prior art devices. Accordingly, in a pressure regulator contemplated by the invention, the spool valve is not connected to the armature. Instead, the armature operates a first stage poppet servo valve. Further, servo pressure is determined by the force balance on the armature, and the resulting servo pressure force has to equal the sum of the magnetic force and a mechanical spring force. Additionally, there is also a force balance on the spool valve, and the spool will move, changing control pressure until the control pressure plus spool spring force equals the servo pressure force. Some of the advantages of a pressure regulator embodying the invention are as follows: 1. Large hydraulic forces are available to move the spool valve instead of low magnetic forces, which substantially improves response time and overcomes potential fouling. 2. Since the position of the spool valve is independent of the position of the solenoid armature, large flows can be accommodated without pressure variation due to changes in armature position. 3. Manufacturability is improved because there is no need to maintain a precise position between the armature and the spool valve and its ports. 4. Hydraulic flow forces do not enter into the armature force balance and therefore do not have a large effect on the regulation of the device. These and other objects and advantages of the invention will become more apparent by reference to the following specification and the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross sectional elevational view of a two-stage embodiment of the present invention; Figure 2 is a cross sectional elevational view of an alternate two-stage embodiment of the present invention; and Figure 3 is a cross sectional elevational view of a second alternative two-stage embodiment of the present invention. Figure 4 is a qualitative curve illustrating the output pressure/current performance of the Figure 1 embodiment. MORE DETAILED DESCRIPTION OF THE DRAWINGS A pressure regulating device for regulating the pressure of a flowing fluid medium is generally shown at 110 in Figure 1. The device 110 includes a stationary generally cylinderical pole piece or member 112 having shape and axially opposed ends 114 and 116. The stationary member 112 also includes a passageway 118 communicating axially therethrough. The device 110 also includes a movable armature means disposed axially from the stationary member 112 for movement axially in relation to the stationary member 112. The armature means comprises a cylinderical shaped armature 120 having an open end 122 spaced axially from the end 114 of the stationary member 112. This creates a working gap 123 between the armature 120 and the end 114 of the stationary member 112. The working gap 123 defines the distance the armature 120 moves in relation to the stationary member 112. The armature 120 also includes a closed end 124 axially opposite the first end 122. The device 110 further includes a coil means disposed partially about the stationary member 112 and the armature 120 and through which an electrical current flows from a source (not shown) for generating magnetic flux to create an attractive force to move the armature 120 in relation to the stationary member 112. The coil means comprises a solenoid coil 126. The current flowing through the solenoid coil 126 may be DC or the average value resulting from a chopped or pulse width modulated electrical supply. The attractive force is proportional to the current and the square of the number of turns of wire on the solenoid coil 126 and inversely proportional to the square of the distance between armature 120 and the end 114 of the stationary member 112. An annular U-shaped bracket member 128 is disposed partially about the stationary member 112 and armature 120, and the solenoid coil 126 is disposed within the bracket member 128, which forms a central passage 130 communicating axially through it. The armature 120 is slideably disposed in the passage 130 while the stationary member 112 is press-fitted into one end of the passage 130. A pair of connectors 132 are disposed in bores 34 formed in the bracket member 128 and connected to the solenoid coil 126 for attachment to an electrical supply source to allow electrical current to flow to the solenoid coil 126. A return member 136 is threadably engaged and disposed about one end of the stationary member 112 and abuts one end of the bracket member 128. The return member 136 creates a closed flux loop by allowing magnetic flux to flow from the solenoid coil 126 through the bracket member 128 and return member 136 to the stationary member 112 and across the working gap 123 to the armature 120 back to the solenoid coil 126. The device 110 includes a housing means encasing the armature 120, solenoid coil 126 and stationary member 112. The housing means comprises an annular casing 138 (first housing portion) about the device 110 to prevent undesired or foreign contaminants from entering the device 110, and it also includes a pair of annular seals 140 and 141 at one end of the bracket member 128 to prevent fluid contaminants from contacting the solenoid coil 126. The device 110 further includes a bleed valve means spaced axially from one end and connected to the armature 120 for moving concurrently with the armature 120. The bleed valve means comprises a valve plate 154 having one end 156 threadably engaging an aperture 158 formed in the closed end 124 of the armature 120. The valve plate 154 has an axially spaced end 160 which operatively cooperates with the valve seat 161 of housing 142. The valve plate 154 also includes an aperture 162 to allow a small predetermined amount of fluid to enter the cavity 164 of the armature 120. The device 110 includes a biasing means for continuously biasing the valve plate 154 toward the valve housing 142. The biasing means comprises a spring 166 disposed within the cavity 164 formed in the armature 120 between an adjustment means 168 and the closed end 124 of the armature 120. The adjustment means is disposed axially within the cavity 164 of the armature for controlling the force of the spring 166 on the armature 120 in relation to the face of the valve housing 142, and it comprises a threaded rod 168 threadably engageable with the stationary member 112 and having one end 170 disposed within the cavity 164 of the armature 120. The device 110 further includes a valve housing, generally indicated at 142, having one or more apertures in the valve housing 142 to allow a fluid medium to enter and exit the valve housing 142 and at the armature 120. Specifically, a first aperture 180 is formed in the valve housing 142 to allow the fluid medium to enter the valve housing 142. A second aperture 182 formed in the valve housing 142 allows the fluid medium to exit the valve housing 142. A third aperture 184 is formed in the valve housing 142 to allow fluid to exit the valve housing 142 and flow back to the sump (not shown). The device 110 further includes a flow valve means moving independently of the armature 120. The flow valve means is similar to that disclosed in copending application, U.S. Serial Number 07/066,693, entitled "Transmission Pressure Regulator" to Ralph P. McCabe. The flow valve means comprises a spool valve 186 having a first end 188 spaced axially from the closed end 124 of the armature 120. The first end 188 of the spool valve 186 includes a first cavity 189 formed therein. The spool valve 186 also includes a first internal passage 190 communicating with the first aperture 180 of the valve housing 142 and the first cavity 189 of the first end 188 to allow the fluid medium to flow from the first aperture 180 to the first cavity 189. The spool valve 186 also includes a second end 192 axially opposite the first end 188 and having a second cavity 193 formed therein. The spool valve 186 also includes an annular recessed portion 194 about the circumference thereof between the first end 188 and the second end 192 thereof. The spool valve 186 also includes a third internal passage 195 communicating with the annular recessed portion 194 and the second cavity 193 to control or move the spool valve 186 independently of the armature 120. A spring 196 may be disposed in the second cavity 193 to bias the spool valve 186 toward the armature 120 to reduce osciliations of the spool valve 186 due to fluid flow. A first alternate two-stage embodiment of the present invention is generally shown at 210 in Figure 2, the parts of Figure 3 that are similar to Figure 2 embodiment having similar reference numbers. The second alternate embodiment 210 is similar in construction to embodiment 110 of Figure 2. The device 210 has the second internal passage 252 extending diagonally outwardly of the valve housing 242 relative to the first internal passage 290. Also, the device 210 includes a flux return washer 298 and eliminates the connectors 32 of the device 110 and substitutes a wire 299 leading from the coil 226. The operation of the device 210 is the same as that of the device 110. Figure 3 illustrates a second alternate two-stage embodiment 310 of the device 110, like parts of the Figure 1 and Figure 2 first alternate two-stage embodiment again being identified with similar reference numerals. The device 310 includes a pole washer 400 at one end of the bracket member 328 and a flux return washer 402 at the other end of the bracket member 328. The device 310 also includes a valve seat 404 disposed within the valve housing 342 with which the valve plate 354 cooperates. Again, the operation of the device 310 is generally the same as that of the device 110. The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings.

Claims: A pressure regulating assembly (110) for regulating the pressure of a flowing fluid medium, comprising a first housing portion (138) and a valve housing (142), an electrical field coil (126), carried by said first housing portion (138), a pole piece (112) situated generally within said field coil (126), a valve seat (161), fluid-flow passage formed through said valve seat (161), said pole piece (112) comprising a pole piece annular axial end face portion (114), an armature (120); at least partly situated generally within said field coil (126), said armature (120) comprising an armature annular axial end face portion (122), wherein said armature (120) is axially situated between said pole piece (112) and said valve seat (161) as to thereby cause said armature annular axial end face portion (122) to be juxtaposed to said pole piece annular axial end face portion (114), a spring (166) normally resiliently urging said armature (120) in a direction away from said pole piece (112) and toward said valve seat (161) as to thereby terminate the flow of said fluid medium out of said fluid-flow passage, wherein said valve housing (142) comprises a generally cylindrical inner chamber, a spool valve (186) situated in said cylindrical inner chamber and movable with respect to said cylindrical inner chamber, said spool valve (186) comprising at least first and second diametrically relatively large and generally cylindrical valving portions engaging the surface of said cylindrical inner chamber, said spool valve (186) further comprising a generally axially extending body situated between and operatively interconnecting said first and second cylindrical valving portions, said generally axially extending body being diametrically relatively small as to thereby define an recessed portion (194) circumferentially between said axially extending body and said cylindrical inner chamber wherein said recessed portion (194) is also axially confined between said first and second generally cylindrical valving portions, a first fluid inlet passage (180) formed in said valve housing (142) at a location as to be generally juxtaposed to said first generally cylindrical valving portion for general control by said first valving portion, second fluid outlet passage (182) formed in said valve housing (142) at a location as to communicate with said recessed portion (194) third fluid outlet passage (184) formed in said valve housing (142) at a location as to be generally juxtaposed to said second generally cylindrical valving portion for general control by said second valving portion, fourth fluid passage (190) communicating between said first fluid inlet passage (180) and said fluid-flow passage formed through said valve seat (161), characterized in that there is provided a bleed valve comprising a valve plate (154) and the said valve seat (161) separating the armature (120) from the spool valve (186), that the biasing spring (166) urges the valve plate (154) toward the valve housing (152) and that the armature (120) moves toward the pole piece (112) due to the magnetic flux of the solenoid coil (126) to disengage the bleed valve. A pressure regulating assembly (110) according to claim 1, wherein said armature (120) comprises first and second axial ends, wherein said first axial end comprises said armature annular axial end face portion (114), and further comprising a valving member (154) carried by said second axial end and movable in unison with said armature (120), said valving member (154) when moved by said armature (120) against said valve seat (161) being effective to terminate flow of said fluid medium out of said fluid-flow passage and toward sump. A pressure regulating assembly (110) according to claim 1 and further comprising adjustment means (168) for selectively adjusting said spring (166) as to thereby selectively adjust the resilient pre-load force exerted by said spring (166) on said armature (120) to thereby selectively determine said magnitude of said electrical current necessary to bring about movement of said armature (120) away from said valve seat (161). A pressure regulating assembly (110) according to claim 3, wherein said adjustment means (168) comprises an axially threadably adjustable spring seat operatively engaging said spring (166). A pressure regulating assembly (110) according to claim 1, wherein said fourth fluid passage is formed in said spool valve (186). A pressure regulating assembly (110) according to claim 4 wherein said fourth fluid passage is formed in said spool valve (186). A pressure regulating assembly (110) according to claim 1 and further comprising a second spring (196) operatively connected to said spool valve (186) as to continually resiliently urge said spool valve (186) in the relative direction in which said second cylindrical valving portion (193) is disposed, wherein said cylindrical inner chamber extends . axially beyond said first cylindrical valving portion as to form an end chamber, wherein said second resilient means (196) is at least in part situated in said end chamber, and further comprising fifth fluid passage communicating between said annular chamber and said end chamber. A pressure regulating asssembly (110) according to claim 1 wherein said armature (120) comprises first and second axial ends, wherein said first axial end comprises said armature annular axial end face portion, and further comprising additional fluid passage means extending through said second axial end of said armature and wherein said additional fluid passage is effective for conveying a portion of said fluid medium as flows through said fluid-flow passage to space existing in and about said armature (120). A pressure regulating assembly (110) according to claim 8 wherein said additional fluid passage comprises calibrated fluid flow restriction (162). A pressure regulating assembly (110) according to claim 1 wherein said armature comprises a cup-like configuration having a generally axial end wall and a cylindrical wall extending axially therefrom having an open end and defining an inner space generally radially confine said cylindrical wall, wherein said axial end wall (61) is disposed as to be juxtaposed to said valve seat (61), further comprising an additional fluid passage extending through said axial end wall and communicating with said inner space, said additional fluid passage being effective to convey a portion of said fluid medium as flows through said fluid-flow passage to said inner space and from said inner space to such additional space as exists between said armature (120) and said electrical field coil (126). A pressure regulating assembly according to claim 10 wherein said additional fluid passage comprises calibrated fluid flow restriction. A pressure regulating assembly according to claim 2 and further comprising additional fluid passage extending through said valving member, wherein said additional fluid passage comprises calibrated fluid flow restriction and wherein said additional fluid passage is effective for conveying a portion of said fluid medium as flows through said fluid-flow passage to space existing in and about said armature.

Inventors: MCCABE RALPH PATRICK, MCCABE, RALPH PATRICK
Applicants: COLTEC IND INC, COLTEC INDUSTRIES INC
Application year: 1990
Main classification: G05D16
IPC codes: G05D16, F16H61, F16H63