WO1997006037A1

WO1997006037A1 - Hydraulic valve control unit for vehicular anti-lock brake and traction control systems

Info

Publication number: WO1997006037A1
Application number: PCT/US1996/012924
Authority: WO
Inventors: Edward N. Fuller; Herbert L. Linkner Jr.; Gerald M. Sivulka; Wendell D. Tackett; Ronald L. Sorensen
Original assignee: Kelsey Hayes Company
Priority date: 1995-08-07
Filing date: 1996-08-06
Publication date: 1997-02-20
Also published as: JPH11511086A; DE19681525T1; AU6896196A

Abstract

A valve control unit for anti-lock and traction control systems for automotive vehicles and valve structures for the valve control unit. The valve control unit has a valve body housing (30) having cylindrical cavities (144) for receiving the internal portion of the valves and a counterbore (148) forming an annular shoulder. Each valve has a radial flange (102) received in the counterbore and seated on the annular shoulder. The periphery of the counterbore is swaged to form an inwardly directed annular lip (154) securing the radial flange in the counterbore. The swaged annular lip also forms a fluid tight seal between the radial lip and the valve body housing. The annular lip is formed by a swaging tool (160) orbited in a rosette pattern. The swaging of the annular lip permits closer spacing between the valves reducing the size and weight of the valve control unit.

Description

TITLE

HYDRAULIC VALVE CONTROL UNIT FOR VEHICULAR ANTI-LOCK BRAKE AND TRACTION CONTROL SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS This apphcation is a continuation-in-part of application Serial No. 08/511,900, filed August 7, 1995, a continuation-in-part of application 08/511,973, filed August 7, 1995, and also claims priority to provisional application 60/002,011, filed August 7, 1995.

BACKGROUND OF THE INVENTION This invention relates in general to hydrauhc valve control units for anti-lock and traction control systems for vehicular applications and, in particular to the design and method of manufacturing the hydraulic valve control units and the individual solenoid actuated valves embodied in the hydraulic valve control units.

Many automotive vehicles being produced today are equipped with hydraulic brake systems which include anti-lock brake systems (ABS) and traction control (TC) systems. As is known in the art, the anti-lock brake systems inhibit the wheels from locking up duiing sudden or panic applications ofthe brake. The traction control system is used to provide engine power to the driven wheel having the highest wheel-to-road friction. The anti-lock brake and traction control systems are considered by many to be the most significant improvement in vehicle safety within the last decade and are presently being offered as standard equipment on many automotive vehicles.

The hydraulic valve portions of most anti-lock brake systems and traction control systems are embodied in a singular compact hydraulic valve control unit, usually in the form of an ali-minum block in which there is incorporated the valves and other components necessary to provide the desired anti-lock braking or traction control functions. The hydraulic valve control unit for the anti-lock brake system includes solenoid actuated isolation valves for isolating the wheel brakes from the hydraulic braking force exerted by the master brake cylinder in response to the depression ofthe vehicle's brake pedal. The hydraulic control unit also includes solenoid actuated hold/dump valves which are activated by an electronic control to dump or reduce the pressure ofthe hydraulic fluid being applied to the brakes, thereby relaxing the braking torque to prevent wheel lockup. The hydraulic control unit may also include low pressure accumulators and a hydrauhc pump to allow fast dumping ofthe brake pressure and to pump the dumped brake fluid back to the master brake cylinder for subsequent anti-lock cycles of a stop.

The control unit for a traction control system has substantially the same components, which are activated by an electronic control unit to apply a braking torque to the driven wheel ofthe vehicle which has tiie lower wheel-to-road friction. By applying a braking torque to the wheel having the lower wheel-to-road friction, the engine torque is directed to the driven wheel having the higher wheel-to-road friction.

The isolation valves, hold/dump valves, accumulators and other components including the electrically driven hydraulic pump are mounted on or in the aluminum block bored as required to receive these components and provide fluid commumcation passageways between these components as required.

Improved reliability and reductions in weight, size and manufacturing costs ofthe control unit as well as each hydraulic valve in the control unit are of prime importance. The manufacturing costs are related to the number and complexity of the machining operations and the number and complexity ofthe assembly operations of each control unit component and the control unit itself.

In the early stages of development ofthe hydraulic valve control units, typified by the general structure shown in U.S. Patent No. 4,828,335, assigned to the assignee ofthe present invention, the solenoid actuated isolation valves and the solenoid actuated solenoid hold/dump valve were threaded into the aluminum block. These valves included a hexagonal-shaped flange to facilitate the rotation ofthe valve body. This hexagonal-shaped flange is adapted to receive a standard size socket wrench by means of which the valve body can be secured to the aliirninum block with sufficient torque to maintain the control valve secure within a threaded bore formed in the aluminum block. The hexagonal flange limited the spacing between the individual solenoid actuated valves such that the size ofthe aluminum housing was relatively large. The threaded bores in the aluminum block and the corresponding threaded portion ofthe valve body were eliminated by Linkner, Jr. in U.S. Patent No. 5,364,067, assigned to the assignee ofthe present invention, as shown in Figure 3 herein. In the control valve taught by Linkner, Jr., the valve body is secured within the bore ofthe aluminum block by a snap ring. A recessed annular groove is provided in the aluminum block to receive the snap ring. A wave washer resiliently holds a radial flange ofthe valve body against the snap ring. U.S. Patent Nos. 4,828,335 and 5,364,067 are incorporated herein by reference as a teaching ofthe prior art.

SUMMARY OF THE INVENTION

The invention relates to a hydraulic valve control unit for an anti-lock brake system having reduced size and weight. The invention further contemplates a hydraulic valve control unit which eliminates threaded components for mounting the valves to the valve housing. The invention further contemplates a hydraulic valve control unit which has minimal machining and assembly operations to significantly reduce its costs. The invention further contemplates solenoid actuated valve assemblies which are adapted to be swaged into the valve housing and are of a design and in a manner adapted to produce a reliable mechanical lock and a reliable fluid seal.

A hydraulic valve control unit for the anti-lock brake system has an isolation and a hold/dump valve for each wheel ofthe vehicle which is controlled during the anti-lock braking system. Each ofthe isolation and hold/dump valves has an internal portion, an external portion, a radial flange intermediate the internal and external portions and an armature displaceable in response to a magnetic field. The control unit further has a valve body housing having a cylindrical cavity receiving a respective one ofthe internal portions ofthe isolation and hold/dump valves. Each cylindrical cavity fiirther includes a counterbore sized to receive the radial flanges of the isolation and hold/dump valves when their internal portions are disposed in its respective cylindrical cavity. An annular shoulder is formed at the bottom of each counterbore forming a seat for the radial flange. The valve body housing further has a swaged annular lip formed about the perimeter ofthe radial flange which locks the radial flange onto the shoulder and forming a leak-tight fluid seal between the radial flange and the valve body housing.

Other hydraulic components such as the low pressure accumulator will be similarly constructed and retained within the housing. Likewise, where traction assist is integrated in the same housing further components including pilot operated switching valves, high pressure accumulators and the like will be similarly constructed such that these valve-like components are threadless and permanently affixed in the control unit. Rather than repair the control unit or replace individual components, the invention contemplates a non-reusable control unit, which may simply be replaced. The valve body housing further includes internal passageways connecting the isolation valves and the hold/dump valves to each other and to selected input and output ports. In a preferred anti-lock brake system embodiment, the valve body housing has at least one low pressure accumulator, a hydraulic pump and intemal passageways connecting the isolation valve to the output ofthe pump, the hold/dump valve to the low pressure accumulator, and the low pressure accumulator to the input ofthe pump.

In the aforementioned preferred embodiment, the valve body housing is swaged inwardly by a swaging tool orbited in a rosette pattem to form the annular tip such that the annular lip has a uniform thickness.

As part of each preferred embodiment, the control unit has a coil-integrated module attachable to the valve body housing. The coil-integrated module has a solenoid coil assembly which includes a flux ring, for each isolation and hold/dump valve mounted in the valve body housing. Each solenoid coil assembly circumscribes the extemal portion of an associated isolation or hold/dump valve and is slidably received over the armature sleeve as the coil-integrated module is detach- ably secured to the valve body housing.

Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description ofthe preferred embodiments, when read in light ofthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a schematic representation of a braking system for an automotive vehicle including an anti-lock hydraulic valve control unit according to the present invention;

FIGURE 2 is a perspective view of an anti-lock hydraulic valve control unit according to the present invention;

FIGURE 3 is a sectional view of a prior art isolation valve for an anti- lock brake system; FIGURE 4 is a sectional view of an isolation valve according to the present invention;

FIGURE 5 is an enlarged view of a radial rim ofthe isolation valve illustrated in FIGURE 4; FIGURE 6 is a schematic representation ofthe orbital motion of a swaging tool in a rosette pattem;

FIGURE 7 is a sectional view of a hold/dump valve according to the present invention;

FIGURE 8 is a sectional view of a second embodiment of an isolation valve according to the present invention;

FIGURE 9 is a sectional view of a third embodiment of an isolation valve according to the present invention;

FIGURE 10 is a sectional view of a fourth embodiment of an isolation valve according to the present invention; FIGURE 11 is a sectional view of a fifth embodiment of an isolation valve according to the present invention; and

FIGURE 12 is a sectional view of a sixth embodiment of an isolation valve according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A schematic diagram of a braking system 10 for one wheel of an automotive vehicle is illustrated in Fig. 1. The braking system 10 includes a hydraulic control unit 12 formed as a housing containing valve and other components as described below. For purposes of clarity of illustration, only one set of components are illustrated in the schematic representation of Fig 1. Typically, however, the hydraulic control unit 12 also embodies corresponding components for the other wheels ofthe vehicle in a well known manner. The braking system 10 also includes a master brake cylinder 16 responsive to the depression of a brake pedal 14 to provide pressurized brake fluid to a slave cylinder 18 of a wheel brake assembly 28 associated with each wheel ofthe vehicle. In the embodiment illustrated in Figure 1, the wheel brake assembly 28 is a disc brake assembly; however, the wheel brake assembly 28 may be a drum brake assembly or any other type of hydraulic brake assembly found on automotive vehicles.

The hydraulic control unit 12 includes normally open isolation valves 20 disposed between the master cylinder 16 and the slave cylinder 18 of the individual brake assemblies 28, at least one low pressure accumulator 24, normally closed hold/ dump valves 22 disposed between the slave cylinder 18 of the individual brake assemblies 28 and the low pressure accumulator 24, and a hydraulic pump 26 con¬ nected between the low pressure accumulator 24 and the inlet to the isolation valves 20. The contiol unit 12 may also include an attenuator 27 between the output ofthe hydraulic pump 26 and the inlet to the isolation valve 20 to limit and smooth fluid flow from the output ofthe pump 26 back to the master cylinder 16.

During normal braking in the absence of wheel lock-up, the operator ofthe vehicle depresses the brake pedal 14 causing the master brake cylinder 16 to provide pressurized brake fluid to the brake slave cylinder 18 of the brake assembhes 28 through the normally open isolation valves 20, thereby providing operator con¬ trolled braking ofthe associated wheels (not illustrated).

When a wheel lock-up condition of one or all ofthe wheels is sensed by an anti-lock electronic brake control sensor (not illustrated), the normally open isolation valves 20 of associated wheels experiencing lock-up conditions are closed to prevent a further increase ofthe brake fluid pressure being applied to the slave cylinders 18 of the associated wheels. Ifthe lock-up condition of an associated wheel continues, the associated normally closed hold/dump valve 22 is opened as needed, to relieve the pressure ofthe brake fluid being applied to the slave cylinder 18. The opening ofthe hold/dump valve 22 allows a predetermined quantity of brake fluid to flow from the slave cylinder 18 into a low pressure accumulator 24. The hydraulic pump 26 pumps the fluid temporarily dumped into the low pressure accumulator 24 back to the inlet side ofthe isolation valve 20 to maintain the pressure ofthe brake fluid in the low pressure accumulator 24 at a value less than the pressure being applied to the slave cylinder 18, so that each time the hold/dump valve 22 is opened it will always result in decreasing the pressure being applied to the slave cylinder 18.

Upon the detection ofthe lock-up condition being terminated, the associated hold/dump valve 22 is closed and the isolation valve 20 is reopened, as needed, to increase the brake fluid pressure being applied to the slave cylinder 18, again maximizing the braking torque applied to the associated wheel.

The construction ofthe hydrauhc control unit 12 is illustrated in Fig. 2. The control unit 12 consists of a valve body housing 30 having at least wall surfaces 32, 34, and 36 and a coil integrated module (CIM) 38 securable to the valve body housing 30 in final assembly. The valve body housing 30 is preferably made from aluminum but may be made from any other metal or alloy having the desired swaging properties as shall be explained hereinafter. For clarity of illustration, only a portion ofthe coil integrated module 38 is shown in Fig. 2. The coil integrated module 38 contains a solenoid coil assembly 40 for each ofthe isolation valves 20 and hold/dump valves 22 required by the anti-lock brake system.

Extending from the wall ofthe valve body housing 30 opposite the wall surface 36 is an electric motor 42 driving the hydraulic pump 26 enclosed within the valve body housing 30. The electrically driven hydraulic pump 26 pumps the brake fluid from the low pressure accumulator 24, as previously described relative to Fig. 1, to maintain the pressure in the low pressure accumulator 24 below the brake fluid pressure being applied to the slave cylinder 18. Mounted within the valve body housing 30 are a requisite number of isolation valves 20 and hold/dump valves 22. Extemal portions ofthe valves 20 and 22 which contain an armature (not illustrated in Fig. 2) extend from the wall surface 32. Each extemal portion is circumscribed by a selected one ofthe solenoid coil assembhes 40 (only one of which is illustrated in Fig. 2) in the coil integrated module 38. In the preferred embodiment, an individual isolation valve 20 and an individual hold/dump valve 22 is provided in the valve body housing 30 for each wheel ofthe vehicle to control the brake fluid pressure being applied to the associated slave cylinder 18.

However, in other types of braking systems, such as a crossed diagonal braking system, only a single isolation valve 20 and a single hold/dump valve 22 may be used to control the brake fluid pressure being applied to the slave cylinders 18 for each diagonally opposite pair of wheels. This reduces the number of isolation valves 20 and dump/hold valves 22 in the control unit 12 to two (2) each. Also, in a vertical split braking system, the rear wheels are activated as a pair and only a single isolation valve 20 and single hold/dump valve 22 are used to control the rear wheels in an anti-lock mode of operation.

Retvj-rning to embodiment illustrated in Fig. 2, each isolation valve 20 and hold/dump valve 22 associated with a particular wheel are aligned with each other. For example, the isolation and hold/dump valves are aligned with each other perpendicular to the wall surface 36 ofthe valve body housing 30. Provided in wall surface 36 ofthe valve body housing 30 are a pair of threaded apertures 44 which are adapted to receive threaded connectors provided on the end ofthe hydraulic lines (not shown) which connect the valve body housing 30 to the master cylinder 16. Also provided in wall surface 36 are four threaded apertures 46 which are adapted to receive threaded connectors on the end ofthe hydrauhc lines (not shown) connecting the valve body housing 30 to the individual slave cylinders 18 associated with the brake assemblies of each wheel. The end caps 48 formed in wall surface 36 enclose one end of four low pressure accumulators 24 (not illustrated in Fig. 2) embodied in the valve body housing 30 and two attenuators 27 (not illustrated in Fig. 2). The end caps 48 may be threaded into the valve housing 30 or swaged in place as shall be discussed hereinafter. Likewise, threaded apertures 44 and 46 may be eliminated in favor of a threadless-type connector, including swaging. Figure 3 illustrates a sectional view of a prior art isolation valve 50 mounted in a hydraulic control unit such as taught by Linkner, Jr. in U.S. Patent 5,364,067. As is obvious to one skilled in the art, the stmcture shown in Figure 3 is equally applicable to hold/dump valves. The prior art isolation valve 50 has a cylindrical sleeve 52 in which a movable armature 54 is slidably received. An annular coil 56 circumscribes the sleeve 52. The armature 54 has a ball valve which engages a valve seat located at one end of a coaxial fluid passage 58 provided through a valve stem 60. The armature 54 is biased away from the valve stem 60 by a spring as shown. The valve stem 60 is locked in a valve body 62 which has a radial flange 64 received through an opening 66 provided in the valve body housing 68. The valve body housing 68 has a valve cavity 70 having an annular recess in which a snap ring 72 is received to inhibit the removal ofthe valve body 62 from the valve cavity 70. An annular wave washer 74 biases the radial flange 64 against the snap ring 72 to lock the valve body 62 in the valve cavity 70.

Annular fluid seals 76 and 78 are disposed in annular grooves formed in the valve body 62 on opposite sides of an intemal passageway 80 provided in the valve body housing 68 which serves as an outlet port while a fluid seal 82 is provid¬ ed between the valve stem 60 and the valve body 62. As can be seen, the valve cavity 70 has several counterbores and an annular recess which increases the complexity and cost ofthe machining of both the valve cavity 70 and the valve body 62. Additionally, the assembly ofthe valve 50 into the valve bore requires two annular seals 76 and 78, a snap ring 72, and a wave washer 74 which increases the assembly complexity, assembly time and cost ofthe anti-lock braking hydrauhc control unit. In addition to the isolation valve 50, the hydraulic control unit may also embody a hold/dump valve, a low pressure accumulator, a pump, and an attenuator in a well known manner.

The constmction of first preferred embodiments ofthe isolation valve 20 and a hold/dump valve 22 according to the present invention are illustrated in Figures 4, 5 and 7. The design of valves 20 and 22 result in a significant reduction in the machining and assembly operations ofthe valves themselves and the valve body housing 30. The structure ofthe isolation valve 20 and its assembly to the valve body housing 30 are shown in Figure 4. The isolation valve 20 has a cylindrical valve body 100 having a radial flange 102. The valve body 100 has a coaxial flow passage 104 provided therethrough which terminates at its upper end in a conical valve seat 106. The lower end ofthe valve body 100 has a reduced diameter portion 108 which has an annular catch 110 adjacent to its lower end. A filter assembly 112 having a filter 114 is received over the reduced diameter portion 108 ofthe valve body 100. The filter assembly 112 has an intemal recess 116 in which the annular catch 110 is received to snap lock the filter assembly 112 to the end ofthe valve body 100 so that the filter 114 covers the lower end ofthe coaxial flow passage 104.

A cylindrical sleeve 120 has an open lower end and an closed upper end 122. The open end is laser welded to the valve body 100 providing a fluid tight seal therebetween. The valve body 100 has a reduced diameter section 118 over which the open end ofthe sleeve 120 is received.

An armature 124 is slidably disposed in the sleeve 120. The armature 124 has an annular flange 126 and an axial bore 128 in which is received a valve member sized to engage the valve seat 106 and block the upper end ofthe coaxial flow passage 104. The valve member is preferably a ball 130. The ball 130 is substantially non-deformable, for example, a steel ball. A coil spring 132 is disposed between the upper end ofthe valve body 100 and the flange 126 and resil¬ iently biases the armature 124 away from the valve body 100 and the ball 130 away from the valve seat 106. As indicated, the aimature 124 and the flange 126 have trough slots 127 providing a fluid passageway between the flange 126 and the closed end 122 ofthe cylindrical sleeve 100. The slots 127 prevent a fluid lock-up condition inhibiting the rapid displacement ofthe aimature 124 relative to the valve body 100.

A coil assembly such as coil assembly 40 shown in Fig. 2 is slidably received over the cylindrical sleeve 120 with a flux ring 164 being in close fitting, sliding engagement with valve body section 118. Optionally, to accommodate manufactiiring tolerances, a slight clearance can be allowed between the flux ring 164 and sleeve 120. The coil assembly 40 is operative, when energized, to produce a magnetic field displacing the armature 124 towards the valve body 100 causing the ball 130 to seat on the valve seat 106. The seating ofthe ball 130 on the valve seat 106 teiTninates the fluid flow between the axial fluid inlet passage 104 and an outlet passageway 134 formed in the valve body housing 30 through intemal passageways 136 formed in the valve body 100. The outlet fluid passageway 134 is connected to an associated threaded aperture 46 and to the input ofthe associated hold/dump valve 22 as shown in Figure 1.

As stated above, the coil assembly 40 includes an annular flux ring 164 disposed at the end adjacent the valve body housing 30. The flux ring 164, such as taught in patent application Serial no. 08/198,365, assigned to the assignee ofthe present invention, issuing as U.S. Patent 5,439,279 on August 8, 1995, the disclosure of which is hereby incoφorated by reference as a further teaching ofthe subject matter, enhances the strength ofthe magnetic field acting on the armature 124 and reduces the current required to produce a magnetic field having a strength sufficient to displace the armature 124 against the force of spring 132.

The valve body 100 further has an annular groove 138 in which is received a one-way seal 140 to prevent a fluid flow from the intemal inlet passageway 142 ofthe valve body housing 30 to the outlet passageway 134. The internal inlet passageway 142 connects to an associated threaded aperture 44, Figure 2, and to the master brake cylinder 16 and to the output ofthe pump 16 as shown in Figure 1.

The valve body housing 30 has a valve cavity 144 for each isolation valve 20 and each hold/dump valve 22 to be mounted therein. The lower or bottom end ofthe valve cavity 144 has an annular recess 146 provided adjacent to the terminal ends of intemal passageways 138 and a counterbore 148 which receives the radial flange 102. Preferably, the diameter ofthe counterbore 148 is slightly smaller than the diameter ofthe radial flange 102, typically about 0.05 to 0.15 mm (.002 to .006 in.), producing an interference fit in the radial sealing area ofthe radial flange 102. The depth ofthe counterbore 148 is typically about 2.0 mm greater than the thickness ofthe radial flange 102 so that when the isolation valve 20 is inserted into the valve cavity, the upper surface ofthe radial flange 102 is approximately 2.0 mm below the adjacent suiface ofthe valve body housing. The diameter ofthe counter bore 148, however, may be slightly larger than the diameter ofthe radial flange 102 so that it is not necessary to press the radial flange 102 into the counterbore during assembly. However, such an arrangement would require an additional fluid seal, for example an "O-ring" seal at the underside of flange 102, to augment loss ofthe fluid seal provided by the press fit radial flange embodiment. To facilitate the press fit insertion ofthe radial flange 102 into the counterbore 148, a portion 156 ofthe radial flange 102 is tapered at approximately 15° to form a truncated cone as shown on the right half side of Figure 5. This truncated cone permits the radial flange 102 to be properly centered into the counterbore 148, and it reduces the insertion forces required to seat the radial flange 102 on the shoulder 150 formed at the bottom ofthe counterbore 148 when the radial flange 102 is an interference fit. The upper edge ofthe radial flange 102 has a beveled edge 158 to increase the shear area and facilitate the sealing ofthe radial flange 102 in the counterbore 148 as shall be explained hereinafter. The truncated cone portion 156 is also used to form an interference fit for either primary or secondary fluid pressure sealing. When used for pressure sealing, the shallow 15 degree angle causes any debris, that might be generated at this interference seal area, to be subducted (squeezed into a portion 102 ofthe interference seal area) rather than be plowed ahead. Altematively, the truncated cone portion 156 could be replaced by a spherically-shaped surface 164 as shown on the left half side of Figure 5 to provide the same centering, sealing, and subducting features.

After the radial flange 102 is seated on the shoulder 150 as shown on the left side of Figure 4, the region 152 ofthe valve body housing 30 adjacent to the edge ofthe counterbore 148 is swaged to a depth from 0.4 to 0.8 mm to form a lip 154 over the upper surface ofthe radial flange 102. The preferred depth ofthe swaged area is 0.6 mm. The beveled surface 158 facilitates the flow ofthe metal of the valve body housing 30 over the radial flange 102 during the swaging process. The swaged lip 154 locks the valve body 100 in the valve bore 144 ofthe valve body housing 30 and produces an excellent fluid tight seal between the outer edge ofthe radial flange and the valve body housing 30.

Preferably, the lip 154 is swaged using a swaging tool 160 orbited in a rosette pattem 162 as shown in Figure 6. The movement ofthe swaging tool 160 in the rosette pattem uniformly swages the lip 154 inwardly over the radial flange 102 as shown on the right side of Figure 4. Preferably, the outer diameter ofthe swaging tool 160 is 4.0 mm greater than the diameter ofthe counterbore 148 and the eccentricity ofthe center line ofthe swaging tool 160 is within 0.5 mm ofthe center line ofthe counterbore 148. This swaging process not only secures the valve body 100 in the valve cavity 144 but also produces an excellent fluid tight seal between the radial flange 102 and the valve body housing 30. During the swaging process, the advance speed ofthe swaging tool 160 is preferably between 2.0 to 2.8 mm/sec. Alternatively, the annular lip 154 could be formed with the same swaging tool orbited in a concentric circular orbital pattem rather than in the rosette pattem. This, however, would require higher loading to form the annular lip 154 but would produce lower vibrations. This same type of swaging process may be used to swage the end caps

48 enclosing the low pressure accumulators and the attenuators in the valve body housing 30, as shown in Figure 1.

The constmction ofthe hold/dump valve 22 is illustrated in Figure 7. Hold/dump valve 22 as shown substantially embodies the subject matter ofthe present invention as discussed above relative to the isolation valve 20 of Figure 4. The hold/dump valve 22 has a generally cylindrical valve body 200 having a radial flange 202, a coaxial outlet passage 204, an inlet passage 206 and an annular seal groove 208. The coaxial outlet passage 204 has a conical valve seat 210 provided at its upper end which is sealingly engaged by a ball valve 212 attached to an armature 214. The ball 212 is a substantially non-deformable steel ball.

The armature 214 is slidably received in a cylindrical sleeve 216 sealed at one end to the valve body 200 and sealed at the other end to a cylindrically- shaped stationary pole piece 218. In the preferred embodiment, the sleeve 218 is laser welded to the valve body 200 and the pole piece 218 forming a fluid tight seal therebetween. A coil spring 220 received in a spring bore 222 provided in the armature 214 resiliently biases the armature 214 away from pole piece 218 and biases the ball 212 to engage the valve seat 210, thus providing the hold/dump valve 22 with a normally closed state. As would be obvious to those skilled in the art, the spring bore 222 may altematively be provided in the pole piece 218. A solenoid coil assembly, such as solenoid coil assembly 40 shown in

Figure 2, is slidably received over the pole piece 218 and the sleeve 216, with the flux ring 164 being in close fitting, sliding engagement with the sleeve 216. Optionally, a slight clearance could be allowed between flux ring 224 and sleeve 216. Coil assembly 40 is operative, when energized, to generate a magnetic field displacing the armature 214 in a direction towards the pole piece 218 disengaging the ball valve 212 from the conical valve seat 210 thus opening a fluid passage from the inlet passage 206 and the coaxial passage 204. As described above, the coil assembly 40 includes an annular flux ring 164 to enhance the strength ofthe magnetic field in the vicinity ofthe armature 214.

The valve cavity 226 provided in the valve body housing 30 has a generally cylindrical shape. The valve body housing 30 further has at least an intemal outlet passageway 228, an inlet passageway 230, an annular recess 232 adjacent to the terminal ends ofthe inlet passageways 206, and a counterbore 234. The counterbore 234, as shown on the left side of Figure 7, is sized to receive the radial flange 202 with a loose fit or an interference fit with the rim ofthe radial flange 202. Likewise, similar to the radial flange 156 ofthe isolation valve 20 illustrated in Figure 5, the rim ofthe radial flange 202 preferably has a truncated conical surface corresponding to truncated conical surface 156 and a beveled edge corresponding to the beveled edge 158. The truncated conical surface facilitates the centering ofthe radial flange 202 in the counterbore 234 and also reduces the force required to insert the valve body 200 into the valve cavity 226 when the counterbore 234 is sized to be an interference fit with the flange 202. An annular filter 236 is received over the valve body 200 with the same snap-fit constmction previously described and covers the teπninal ends ofthe inlet passages 206 and a one-way seal 238 is disposed in the annular seal recess 208 to prevent a fluid flow from the inlet port 232 to the outlet port 228.

After the radial flange 202 is properly seated on the shoulder 240 formed at the bottom ofthe counterbore 234, the region 242 ofthe valve body housing 30 adjacent to the counterbore 234 is swaged to form an annular lip 244 which secures the radial flange 202 to the valve body housing 30. Preferably, the region 242 is swaged using a swaging tool, such as swaging tool 160 shown on Figure 6, orbited about the edge ofthe counterbore in a rosette pattem 162 to form the lip 244, as shown on the right side of Figure 7.

As discussed above relative to the isolation valve 20 shown on Figure 4, the swaged lip 244 not only secures the valve body 200 to the valve body housing 30 but also may, because ofthe press fit between the flange 202 and the wall ofthe counterbore 234, form an excellent primary fluid seal prohibiting the pressurized brake fluid received through the inlet passageway 230 from leaking past the radial flange without the need for a separate O-ring seal at this interface.

The use of a separate flux ring 164 as part ofthe coil assembly 40 facilitates downsizing ofthe valves and thus the valve body bores. Further, it facilitates the swaging or other non-threaded connection ofthe isolation and hold/dump valves to the valve body housing 30 which, in turn, permits even further downsizing ofthe valves, other components and valve body overall.

The valve body housing 30 as previously described, will have intemally provided therein, the requisite fluid passageways 142 connecting the threaded ports 44 to the isolation valves 20, fluid passageways 132, 230 connecting the outlet ports ofthe isolation valves 20 to the threaded outlet ports 46 and to the associated hold/dump valves 22, intemal fluid passageways 228 connecting the outlet ports ofthe hold dump valves 22 to the low pressure accumulators 24, intemal passageways connecting the low pressure accumulators 24 to the pump 26, and intemal passageways connecting the outlet ofthe pump 26 to the attenuator 27 and back to the input ofthe isolation valves 20 as shown in Figure 1. The valve body housing 30 will also house the moving components ofthe hydrauhc pump 26, the component parts ofthe low pressure accumulator 24 and the components ofthe attenuator as is known in the art.

Valves 20 and 22 mounted in the valve body housing 30 constimte a hydraulic control unit 12 which may be characterized as a "throwaway" modular control unit. If a valve 20 or 22 did not deliver desired results, the control unit 12 can be discarded rather than repaired since the assembly ofthe valve 20 or 22 is accomplished by swaging, rather than by a valve body threaded into a bore as disclosed in U.S. Patent 4,828,335.

A second preferred embodiment of an isolation valve 20' according to this invention and its assembly to the valve body housing 30 is illustrated in Figure 8. In comparison with the embodiment of Figure 4, like reference numerals followed by a prime symbol ( ' ) are used to indicate the similar or identical features common to both embodiments. The isolation valve 20' has a cylindrical valve body 100'. The valve body 100' has a coaxial flow passage 104' provided therethrough which terminates at its upper end in a conical valve seat 106'. The lower end ofthe valve body 100' has an enlarged diameter portion 108'. A filter assembly 112' having a filter 114' is received within a counterbored portion ofthe valve body 100' adjacent inlet passageway 142'. A cylindrical sleeve 120' has an open end and a closed end 122'. The open end is laser welded to an annular retainer ring or collar 160 described below, providing a fluid tight seal therebetween. The valve body 100' has a reduced diameter section 118' over which the open end ofthe cylindrical sleeve 120' and retainer ring 160 are received. A passageway 136' (only one of which is shown) is in the form of an extemal trough slot, thereby allowing it to be milled at the outer surface ofthe valve body 100'. Preferably two or more such passageways 136' will be provided.

An armature 124' is slidably disposed in the cylindrical sleeve 120'. The armature 124' includes an annular flange 126' and an axial bore 128' in which is received a valve member sized to engage the valve seat 106' and block the upper end ofthe coaxial flow passage 104'. The valve member is preferably a ball 130'. The ball 130' may be a steel ball but preferably is a substantially non-deformable ceramic ball as described earlier. A coil spring 132' is disposed between the upper end ofthe valve body 100' and the flange 126' and resiliently biases the armature 124' away from the valve body 100', thereby allowing the ball 130' to move away from the valve seat 106'. As stated above, the armature 124' and the flange 126' have trough slots 127' providing a fluid passageway between the flange 126' and the closed end 122' ofthe cylindrical sleeve 120'. The slots 127' prevent a fluid lock-up condition inhibiting the rapid displacement ofthe armature 124' relative to the valve body 100'. A coil assembly (not illustrated) such as previously described coil assembly

40 in Figure 4 is received over the cylindrical sleeve 120' and is operative, when energized, to produce a magnetic field displacing the armature 124' towards the valve body 100' causing the ball 130' to seat on the valve seat 106'. The seating ofthe ball 130' on the valve seat 106' terminates the fluid flow between the axial fluid passage 104' and an outlet passageway 134' formed in the valve body housing 30 through the passageways 136' in the valve body 100'. The outlet fluid passageway 134' is connected to an associated threaded aperture 46 and to the input ofthe associated hold/dump valve 22.

The intemal inlet passageway 142' connects to an associated threaded aperture 46, the master cylinder 16, and the output ofthe pump 26 as shown in Figure 1.

The valve body housing 30 has a valve cavity 144' for each isolation valve 20' and each hold/dump valve 22 to be mounted therein. The lower or bottom end ofthe valve cavity 144' has an annular recess 146' provided adjacent to the terminal ends of intemal passageways 136' and a counterbore 148' leading into inlet 142. The counterbore 148' provides a tapered shoulder 150' which provides a stop for the valve body 100'.

The retainer ring 160 with attached sleeve 120' is slidably received over the reduced diameter section 118' ofthe valve body 100'. The ring 160 includes a compression seal member 162, such as an O-ring, within an annular groove to preclude fluid escaping extemally ofthe cavity 144'. The retainer ring 160 also includes an interior curvilinear, radiused surface 164 mating with an adjacent complementary suiface or shoulder on the valve body 100', preferably in the form of a tmncated conical surface, providing a secondary fluid seal at this interface during the assembly process described below, as well as serving to hold the valve body 100' on shoulder 150'. Further, at its other end, the intemal bore ofthe retainer ring 160 is counterbored to receive the open end of sleeve 120' prior to being laser welded thereto. Thus, the intemal diameter ofthe sleeve 120' and nrinimum diameter ofthe retainer ring 160 are the same and sized to provide a sliding fit with valve portion 118'.

After the valve body 100' is seated on the shoulder 150' and the retainer ring and sleeve assembly 160, 120 is in place as shown on the left side of Figure 8, an annular hp 154' ofthe valve body housing 30 adjacent to the edge ofthe bore 144' is swaged to form a valve retention hp 154' over the upper suiface ofthe retainer ring 160. The swaged lip 154' locks the valve body 100' in the valve bore 144' ofthe valve body housing 30 and produces an excellent fluid tight seal at the shoulder 150', thereby precluding fluid flow from inlet passageway 142' to the outlet passageway 134'.

The annular lip 154' may be formed by initially machining an annular groove 156 in the valve body housing 30 concentric with bore 144'. During assembly, the hp 154' is preferably cone swaged using a swaging tool as taught in U.S. Patent No. 5,364,067, assigned to the assignee ofthe present invention hereby incoφorated by reference as a teaching of the process.

A hold/dump valve such as valve 22 shown in Figure 7 could be constructed and retained in the valve body housing 30 by a retainer ring 160 in the same manner as valve 20' illustrated in Figure 8.

A third preferred embodiment of an isolation valve 320' according to this invention and its assembly to the valve body housing 30 is illustrated in Fig. 9. Reference numerals in the 300 series are used for elements of isolation valve 320' corresponding to similar or identical elements present in isolation valve 20' illustrated in Fig. 8. The isolation valve 320' includes a valve body 300, a ball 306 and an armature 324. A sleeve 320 has a closed upper end 322 and open lower end. The lower end ofthe sleeve 320 extends downwardly between a retainer ring 360 and the valve body 300. Preferably, the sleeve 320 teiminates in a beveled portion pressed onto a curvilinear section, preferably formed as a truncated cone, ofthe valve body 300 formed between a reduced diameter portion 318 and an enlarged diameter portion 308. By pressing the sleeve 320 onto the valve body 300, a weld is not required between the two elements.

After the valve body 300 with the sleeve 320 is inserted into a bore 344, the retaining ring 360 is slid over the sleeve 320 and fitted onto the valve body 300. An annular lip 354 is formed from the material adjacent the bore 344. The lip 354 can be formed by radial swaging, or preferably by cone swaging (not illustrated). If cone swaging is utilized, an annular groove 356 can be formed in the valve body housing 30 prior to the swaging process.

It will be apparent to one skilled in the art that a hold/dump valve 22 can be formed with elements similar to the sleeve 320 and retainer ring 360 used in isolation valve 320'.

A fourth prefeπed embodiment of an isolation valve 420' according to this invention and its assembly to the body housing 30 is illustrated in Fig. 10. Reference numerals in the 400 series are used for elements of isolation valve 420' conesponding to similar or identical elements in isolation valve 320' illustrated in Fig. 9. Isolation valve 420' includes a sleeve 420 terminating in a beveled portion trapped between a retainer ring 420 and a valve body 400. A bevel 466 is formed along the upper outer surface ofthe retainer ring 460 prior to the swaging process. An annular lip 454 is foimed by a cone swaging process which presses against the bevel 466 to trap the retainer ring 460 and provide axial sealing . If desired, an annular groove 468 can be formed in the inner surface ofthe bore ofthe retaining ring 460. A seal 470, illustrated as a compressible O-ring, can be received in the groove 468 to provide a seal between the retainer ring 460 and the sleeve 420. If desired, an annular groove 472 can be formed in the outer surface ofthe retaining ring 460. A seal 462, illustrated as a compressible O-ring, can be received in the groove 472 to provide a seal between the retainer ring 460 and the valve body housing 30. An angled shoulder 450, preferably at 45 degrees or greater, is provided in the lower counterbore 448 ofthe valve body housing 30 to provide a relative small area of contact between the valve body housing 30 and the valve body 400. This small area provides a high sealing stress and seal seating.

A fifth prefeπed embodiment of an isolation valve 520' according to this invention and its assembly to the valve body housing 30 is illustrated in Fig. 11. The isolation valve 520' includes a generally cylindrical valve body 500. The valve body 500 includes a coaxial flow passage 504 provided therethrough which terminates at its upper end in a conical valve seat 506. The coaxial passageway 504 is in fluid communication with a fluid inlet 542 formed in the valve body housing 30. The lower end ofthe coaxial flow passage 504 may terminate in a counterbore 505. If desired, a fluid filter (not illustrated) can be adapted to lower end ofthe coaxial flow passage 504. For example, a filter assembly such as filter assembly 112 for valve body 100 of Fig. 4 can be adapted for the lower end ofthe valve body 500. In another illustrative example, a filter assembly such as filter assembly 112' and counterbore 148' for valve body 100' of Fig. 8 can be adapted for the valve body housing 30 of Fig. 11.

The valve body 500 includes a lower, enlarged diameter portion 508 and an upper, reduced diameter portion 518. A radial flange 502 is formed between the lower portion 508 and the upper portion 518. Preferably, a plurahty of intemal fluid passageways 536 are formed through the upper portion 518. The intemal passageways 536 are in fluid communication with an outlet port 534 foimed in the valve body housing 30. An annular groove 538 is formed about the circumference ofthe lower portion 508. A seal 540, illustrated as a compressible O-ring seal, is received in the groove 538 to prevent the flow of fluid from the inlet port 542 to the outlet passageway 534. The valve body housing 30 has a valve cavity 544 for each isolation valve

520' and each hold/dump valve. A counterbore 548 provides a stepped shoulder 550 which provides a stop for the radial flange 502.

A sleeve 520 has an open end which is fitted over the reduced diameter portion 518 ofthe valve body 500. The sleeve 520 houses a shdable armature 524 biased by a spring 532 and fimctions in a manner similar to armamre 124 of Fig. 4. A coil assembly 40 (not illustrated in Fig. 11) is placed over the sleeve 520 and energized to slide the aimature 524 away from the valve body 500 so that ball 530 moves away from valve seat 506 to permit fluid to flow from the inlet passage 542 to the outlet passage 134. Preferably, an angled shoulder 519 in the form of a tmncated cone is foimed on the outer chcumference ofthe valve body 500 between the reduced diameter portion 518 and the radial flange 502. The lower end ofthe sleeve 520 is preferably fitted or pressed about the shoulder 519 so that an inner surface ofthe sleeve 520 is fitted against an outer surface ofthe flange 502 in a sealing manner. In this manner, the sleeve 520 does not have to be welded to the valve body 500.

A retainer ring or collar 560 is slid over the sleeve 520 and rests on the shoulder 550 ofthe valve body housing 30. Preferably, an inner surface ofthe retainer ring 560 is complementary to the outer surface ofthe sleeve 520. An annular groove 572 is foimed in an outer surface ofthe retainer ring 560. A seal 562, illustrated as a compressible O-ring seal, is fitted in the groove 572 and provides a fluid seal between the valve body housing 30 and the retainer ring 560. A second annular groove 568 is formed in an inner suiface ofthe retainer ring 560. A seal 570, illustrated as a compressible O-ring seal, is fitted in the groove 568 and provides a fluid seal between the sleeve 520 and the retainer ring 560.

After the valve body housing 30 is seated on the shoulder 550 and the retainer ring 560 is in place as shown on the left half of Fig. 11, a preferably annular hp 554 ofthe valve body housing 30 adjacent the counterbore 548 is formed over and engages the upper surface ofthe retainer ring 560, as shown on the right half of Fig. 11. The annular lip 554 secures the retainer ring 560 and valve body 500 in the bore 544 ofthe valve body housing 30. The annular hp 554 is preferably cone swaged using a swaging tool as described above for the embodiment of Fig. 8. In other embodiments, the lip 554 can be formed by any desirable manner. In yet other embodiments, the lip 554 can be formed as a segmented annular member.

It will be apparent to one skilled in the art that a hold/dump valve 22 can be foimed with elements similar to the sleeve 520 and retainer ring 560 used in isolation valve 520'. A sixth prefeπed embodiment of an isolation valve 620' according to this invention is illustrated in Fig. 12. The isolation valve 620' includes a valve body 600 having a lower portion 608, an upper portion 618 and a radial flange 602 formed between the portions 608, 618. The upper portion 618 includes a stepped portion 619 having a larger diameter. A sleeve 620 is fitted over the upper portion 618 and stepped portion 619 and terminates in an upwardly projecting annular flange 621. A retainer ring or collar 660 includes an annular cylindrical portion 661 having an outer annular radial flange 663. Preferably, a lower portion ofthe cylindrical portion 661 has thickness which is complementary to and received in an annular gap 623 foimed between the annular flange 621 and the sleeve 620. After the radial flange 602 is seated on the shoulder 650 and the retainer ring

660 has been seated in the gap 623, a preferably annular lip 654 ofthe valve body housing 30 adjacent the bore 644 is formed over and engages the upper suiface of the retainer ring 660. The annular lip 654 secures the retainer ring 660 and valve body 600 in the bore ofthe valve body housing 30. The annular lip 654 is preferably swaged using a swaging tool as described above for the embodiment of Fig. 4. In other embodiments, the lip 654 can be foimed by any desirable manner. In yet other embodiments, the lip 654 can be foimed as a segmented annular member. It will be apparent to one skilled in the art that a hold/dump valve 22 can be foimed with elements similar to the sleeve 620 and retainer ring 660 used in isolation valve 620'.

In accordance with the provisions ofthe patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its prefeπed embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.

Claims

What is claimed is:

1. An anti-lock brake control unit for a braking system of an automotive vehicle having a master brake cylinder providing a pressured brake fluid to the slave cylinders ofthe brake assemblies of each wheel in response to the depression of a brake actuator by an operator ofthe vehicle, said control unit comprising: an isolation valve for at least one wheel ofthe automotive vehicles, said isolation valve having an intemal portion and extemal portion and a radial flange intermediate said intemal and extemal portion, said extemal portion including an armature displaceable in response to a magnetic field to change said isolation valve from an open state to a closed state; a hold/dump valve for said at least one wheel ofthe automotive vehicle, said hold dump valve having an intemal portion, an extemal portion and a radial flange intermediate said intemal and extemal portions, said extemal portion including an armature displaceable in response to a magnetic field to change said hold/dump valve from a closed state to an open state; a valve body housing having a plurality of cylindrical cavities in which said intemal portions of said isolation and hold/dump valves are respectively received, each cylindrical cavity further having a counterbore forming a shoulder at the bottom thereof forming a seat for said radial flanges of said isolation and hold/dump valves and a swaged annular lip extending over the edge ofthe radial flange of each ofthe isolation and hold/dump valves, said swaged annular hp mechanically securing said radial flange to said shoulder and to said valve body housing and foπning at least a secondary fluid seal between said radial flange and said valve body housing, said valve body further having at least one inlet port for receiving pressurized brake fluid from the master cylinder, a plurahty of outlet ports for transmitting pressurized brake fluid to the slave cyhnders ofthe brake assemblies for each wheel, at least one low pressure accumulator, and intemal passageways connecting said at least one inlet port to the inputs of said isolation valves, for con- necting the outputs of said isolation valves to the inputs of an associated hold/dump valve and to an associated one of said outlet ports and for connecting the output of each hold and dump valve to said at least one low pressure accumulator and for connecting said at least one low pressure to an input to said pump and an output of ' 5 said pump to said inputs of said isolation valves.

2. The control unit of claim 1 further including a coil integrated module mounted to said valve body housing, said coil integrated module having a solenoid coil assembly, including a flux ring, for each isolation valve and each hold/dump

10 valve mounted in said valve body housing, each flux ring of said solenoid coil assembly circumscribing a selected one of said extemal portions of said isolation and hold/dump valves and each solenoid coil assembly operative, when energized, to produce a magnetic field sufficient to displace said armature in said selected one isolation and hold/dump valves.

15

3. The control unit of claim 2 wherein the flux ring of each coil assembly is secured to the coil assembly at the end adjacent to said valve body housing.

4. The control unit of claim 1 wherein said swaged annular lips are 20 foimed by a swaging tool orbited in a rosette pattem to swage the region of said valve body housing adjacent to said counterbore inwardly to form said annular hp.

5. The control unit of claim 4 wherein said radial flanges of said isolation and said hold/dump valves, respectively, have a predetermined thickness,

25 the depth of said shoulder foimed at the bottom of said counterbore is approximately 2.0 mm greater than said thickness of said radial flange.

6. The control unit of claim 5 wherein said counterbore has a diameter of 0.05 to 0.15 mm smaller than said radial flange such that said radial flange is an interference fit with the intemal wall of said counterbore.

7. The control unit of claim 6 wherein said valve body housing is swaged to a depth in the range from 0.4 mm to 0.8 mm.

8. The control unit of claim 6 wherein said valve body housing is swaged to a depth of approximately 0.6 mm.

9. The control unit of claim 7 wherein said valve body housing is swaged in an area circumscribing said counterbore having a diameter approximately 4.0 mm greater than the diameter of said counterbore.

10. The control unit of claim 2 wherein said isolation valve comprises : a cylindrical valve body having a first end and a second end, said radial flange disposed intermediate said first and second ends, an axial fluid passage¬ way provided through said valve body, a valve seat provided at the end of said coaxial bore adjacent to said first end, and at least one offset fluid passageway providing a fluid passage from said one end of said valve body to a location intermediate said radial flange and said second end of said valve body; a cylindrical sleeve having a closed end and an open end, said open end being sealingly attached to said first end of said body; an armature disposed in said cylindrical sleeve resiliently biased away from said valve seat; and a valve member attached to said armature in ahgnment with said valve seat, said valve member operative to engage said valve seat blocking a fluid flow from said coaxial fluid passageway to said offset fluid passageway when said armature is displaced towards said valve body by the magnetic field generated by the associated solenoid coil assembly when energized.

11. The control unit of claim 10 wherein said valve body has a filter assembly attached to said second end of said valve body to filter the brake fluid re¬ ceived at said inlet port of valve body housing.

12. The control unit of claim 10 wherein said valve member is a ball.

13. The control unit of claim 6 wherein a portion of the rim of the radial flange is tapered to facilitate the insertion of said radial flange in said counterbore.

14. The control unit of claim 13 wherein said portion ofthe rim of said radial flange is tapered at an angle of approximately 15°.

15. The control unit of claim 13 wherein the upper surface ofthe rim of the radial flange is beveled.

16. The control unit of claim 6 wherein the rim of said radial flange is a spherical surface.

17. The control unit of claim 2 wherein said hold dump valve comprises: a cylindrical body having a first end and a second end, said cylindrical valve body having said radial flange disposed intermediate said first and second ends, a coaxial fluid passage provided through said valve body, a valve seat provided at the end of said coaxial fluid passage adjacent to said first end, and at least one offset fluid passageway passing from said one end of said valve body and exiting said valve body at a location intermediate said radial flange and said second end of said valve body; a cylindrical sleeve having a closed end and an open end attached to said valve body; an aimature disposed in said cylindrical sleeve intermediate said closed end and said valve seat, said armature resiliently biased towards said valve seat; a valve member attached to said armature on the side adjacent to said first end, said valve member engaging said valve seat blocking a fluid flow between said coaxial fluid passage and said offset fluid passageway, said valve member displaceable away from said valve seat when said armature is displaced away from said valve body by the magnetic field generated by the associated solenoid coil assembly when energized.

18. The control unit of claim 17 further including a fluid filter circumscribing said valve body at the location where said at least one offset fluid passageway exits said valve body.

19. A valve control unit comprising: at least one solenoid valve having an inlet port, an exit port, an intemal portion, an extemal portion and a radial flange intermediate said intemal and extemal portions, said extemal portions including an aimature displaceable in response to a magnetic field; and a valve body housing having a valve cavity receiving the intemal portion of said at least one solenoid valve, said valve cavity having a counterbore having a diameter selected to receive said radial flange, a seat for said radial flange provided at the bottom of said counterbore, axially locating the associated solenoid valve in said valve cavity, said valve body housing further having a circumferential swaged hp extending from the edge of said counterbore toward the center of said valve cavity, said swaged lip mechanically locking said radial flange against said shoulder and forming at least a secondary fluid seal between said radial flange and said valve body housing, said valve body further having an inlet port, an exit port, and intemal fluid passageways connecting said inlet port and said exit port to said at least one solenoid valve.

20. The valve control unit of claim 19 wherein said radial flange has a predetermined thickness, said shoulder foimed at the bottom of said counterbore is located from an adjacent face of said valve body housing a distance approximately equal to said predetermined thickness of said radial flange plus approximately 2.0 mm.

21. The valve control unit of claim 20 wherein the diameter of said counterbore is approximately 0.05 to 0.15 mm less than the diameter of said radial flange.

22. The valve control unit of claim 19 further including a solenoid coil assembly for said at least one solenoid valve, said solenoid coil assembly circumscribing said extemal portion of said solenoid valve and capable of generating a magnetic field sufficient to displace said aimature in said solenoid valve when energized.

23. The valve control unit of claim 22 wherein said solenoid coil assembly has an annular flux ring at an end adjacent to said valve body housing.

24. The valve control unit of claim 22 wherein said at least one solenoid valve comprises at least two solenoid valves and wherein at least one of said at least two solenoid valves is an isolation valve having a normally open state and switchable to a closed state in response to the displacement of said armature.

25. The valve control unit of claim 22 wherein at least one of said at least two solenoid valves is a dump valve having a normally closed state and switchable to an open state in response to the displacement of said armature.

26. The valve control unit of claim 25 wherein said swaged lip is formed by a swaging tool orbited in a rosette pattem swaging a region of said valve body housing adjacent to said counterbore inwardly.

27. The valve control unit of claim 26 wherein said region has a diameter of approximately 4.0 mm greater than the diameter of said counterbore.

28. The valve control unit of claim 26 wherein said region is swaged to a depth of 0.4 to 0.8 mm.

29. The valve control unit of claim 10 wherein said at least one valve is a plurality of isolation and dump valves mounted on said valve housing to form an anti-lock braking unit for an automotive vehicle.

30. A valve mountable in a valve housing having a valve cavity and a counterbore foiming a flange shoulder comprising: a cylindrical valve body receivable in the valve cavity, said valve body having a first end, an opposite end and a radial flange intermediate said first and opposite ends receivable in said counterbore and seatable on said flange shoulder; a concentric fluid passageway provided in said valve body extending from said first end to said opposite end, said concentric fluid passageway having a valve seat provided adjacent to said first end; an offset passageway provided in said valve body extending from said first end at a location radially offset from said concentric fluid passageway and exiting said valve body at a location intermediate said radial flange and said opposite end; a cylindrical sleeve having a closed end and an open end, said open end of said cylindrical sleeve sealingly attached to said first end of said valve body and said cylindrical sleeve extending concentrically therefrom; an armature slidably disposed in said cylindrical sleeve; means for biasing said aimature relative to said valve body; and a ball valve attached to said armature in ahgnment with said valve seat, said ball valve blocking a fluid flow in said concentric fluid passageway when said ball valve is engaged with said valve seat.

31. The valve of claim 30 wherein said cylindrical sleeve is laser welded to said first end of said valve body.

32. The valve of claim 31 wherein said means for biasing, biases said armature towards said first end of said valve body and said ball valve into contact with said valve seat to form a normally closed valve.

33. The valve of claim 32 further including a solenoid coil ciicumscribing said cylindrical sleeve for generating, when energized, a magnetic field sufficient to displace said armature in a direction away from said valve body and displace said ball valve away from said valve seat.

34. The valve of claim 33 wherein said solenoid coil has a flux ring disposed at a location displaced from said closed end of said cylindrical sleeve.

35. The valve of claim 32 wherein said closed end of said cylindrical sleeve is a cylindrical magnetically susceptible pole pieces sealed to the end of said cylindrical sleeve opposite said valve body to increase the strength ofthe magnetic field in the vicinity of said armature.

36. The valve of claim 30 wherein said means for biasing, biases said armature in a direction away from said first end of said valve body displacing said ball valve away from said valve seat to form a normally open valve.

37. The valve of claim 36 further including a solenoid coil circumscribing said cylindrical sleeve for generating a magnetic field sufficient to displace said armature towards said first end of said valve body and to displace said ball valve against said valve seat.

38. The valve of claim 37 wherein said solenoid coil has an annular flux ring disposed at a location displaced from said closed end of said cylindrical sleeve.

39. The valve of claim 30 wherein a portion ofthe rim of said radial flange is tapered.

40. The valve of claim 39 wherein said portion ofthe rim of said radial flange is tapered at an angle of approximately 15°.

41. The valve of claim 38 wherein the upper edge of the rim of the radial flange is beveled.

42. The valve of claim 30 wherein the rim of said radial flange is a curved surface.

43. A method for making a valve control unit having a valve housing and at least one valve disposed in said valve housing, said valve housing having a valve cavity provided therein for each of said at least one valves, each valve of said at least one valve having an intemal portion, an extemal portion and a radial flange intermediate said intemal and extemal portions, said method comprising: providing a counterbore in said valve housing concentric with each of said valve cavities, said counterbore having a diameter selected to receive the radial flange of said at least one valve, said counterbore forming an annular shoulder at the bottom thereof; inserting said intemal portion of said at least one valve into a respective one of said valve cavities with said radial flange abutting said annular shoulder; and swaging a region of said housing adjacent to said counterbore in an inwardly direction to form an annular hp about each counterbore, said lip locking said radial flange onto said shoulder and forming a fluid tight seal between said radial flange and said housing.

44. The method of claim 43 wherein said radial flange has a predetermined thickness, said step of providing a counterbore provides said annular shoulder at a depth approximately equal to the thickness of said radial flange plus 2.0 mm.

45. The method of claim 44 wherein said step of swaging swages said region to a diameter approximately 4.0 mm greater than the diameter of said counter¬ bore.

46. The method of claim 44 wherein said step of swaging swages said region to a depth between 0.4 and 0.8 mm.

47. The method of claim 43 wherein said step of swaging comprises the step of orbiting a swaging tool engaging said region about said counterbore in a rosette pattem to form said annular lip.

48. The method of claim 43 wherein said radial flange of said at least one valve has an outer rim and wherein a portion of said outer rim has a tapered portion to facilitate the location ofthe radial flange in said counterbore.

49. The method of claim 43 wherein said outer rim of said radial flange is a curved surface.

50. The method of claim 43 wherein said valve control unit is a valve control unit for an anti-lock brake system for an automotive vehicle, said valve control unit having an isolation valve and a hold dump valve for each wheel ofthe automotive vehicle and each of said isolation and hold/dump valves has a radial flange and wherein said valve housing has a valve cavity for each of said isolation and hold/dump valves and each valve cavity has a counterbore for respectively receiving said radial flanges of said isolation and hold/dump valves.

51. A solenoid valve comprising: a cylindrical housing having a first chamber and a second chamber formed therein, said first chamber communicating with an inlet port and said second chamber communicating with an outlet port, said valve housing further having a valve seat provided between said first and second chambers; an armature disposed in said valve housing displaceable between a first position and a second position; and a valve member attached to said armature, said valve member foimed from a substantially non-deformable material, said valve member engaging said valve seat when said aimature is in said first position to inhibit a fluid flow from said first chamber to said second chamber and said valve member displaced from said valve seat when said armature is in said second position permitting a fluid flow from said first chamber to said second chamber.

52. The solenoid valve of claim 51 wherein said valve member is a ball.

53. The solenoid valve of claim 51 further including means for resiliently biasing said aimature towards said first position and a solenoid coil for generating a magnetic field sufficient to displace said armature towards said second position.

54. The solenoid valve of claim 51 further including means for resiliently biasing said aimature towards said second position and a solenoid coil for generating a magnetic field sufficient to displace said armature towards said first position.

55. A throwaway modular isolation valve control unit comprising: at least one isolation valve having an intemal end, an extemal end and a radial flange intermediate said intemal and extemal ends; and a valve housing member having a valve cavity in which said intemal end of said isolation valve is received, a counterbore forming a seat for said radial flange and a swaged annular lip extending over an outer portion of said radial flange to lock said radial flange to said seat and secure said intemal end in said valve cavity.

56. The control unit of claim 55 wherein said radial flange has an interference fit with said counterbore to form a fluid tight seal therebetween.

57. The control unit of claim 55 wherein the diameter of said radial flange is approximately 0.2 to 0.6 mm larger than the diameter of said counterbore.

58. The control unit of claim 57 wherein said radial flange has a predetermined thickness, said shoulder formed by said counterbore is provided at a depth approximately equal to said predetermined width plus approximately 2.0 mm.

59. The control unit of claim 57 wherein an area ofthe valve housing member which is swaged to form the swaged lip has a diameter of approximately 4.0 to 8.0 mm greater than the diameter ofthe counterbore and is swaged to a depth

60. The control unit of claim 56 wherein a portion of the rim of said radial flange is tapered to facilitate the press fit of said radial flange into the counterbore.

61. A throwaway modular hold/dump control unit comprising: at least one hold/dump valve having an intemal end, an extemal end, and a radial flange disposed intermediate said intemal and said extemal ends; and a valve housing member having a valve cavity in which said intemal end is disposed, a counterbore foiming a seat for said radial flange and a swaged annular lip extending over an outer portion of said radial flange to lock said radial flange to said seat and secure said intemal end in said valve cavity.

62. The control unit of claim 61 wherein said radial flange has an interference fit with said counterbore to form a fluid-tight seal therebetween.

63. The control unit of claim 62 wherein the diameter of said radial flange is approximately 0.05 mm to 0.15 mm larger than the diameter of said counterbore.

64. The control unit of claim 61 wherein said radial flange has a predetermined thickness, said shoulder formed by said counterbore is located at a depth approximately equal to said predeteπnined thickness plus 2.0 mm.

65. The control unit of claim 64 wherein an area ofthe valve housing member which is swaged to form said swaged hp has a diameter of 4.0 mm to 8.0 mm greater than the diameter ofthe counterbore and is swaged to an depth of 0.4 to 0.8 mm.

66. The control unit of claim 63 wherein a portion ofthe rim ofthe radial flange is tapered to facihtate the press fit ofthe radial flange into the counterbore.

67. A hydraulic valve control unit comprising: a valve body having a first diameter section, a second diameter section, and shoulder means foimed adjacent the intersection ofthe first and second diameter sections; a valve housing having a bore for receiving at least the first diameter section of the valve body; a retaining ring received over the second diameter section ofthe valve body and mated to the valve body shoulder; and a lip formed in the valve housing about the valve housing bore over the retaining ring to secure the valve body to the valve housing.

68. The hydrauhc valve control unit defined in Claim 67 wherein the second diameter section ofthe valve body has a diameter less than the a diameter of the first diameter section.

69. The hydrauhc valve control unit defined in Claim 67 wherein the retaining ring includes a central bore having a curvilinear, radiused surface mating with an adjacent complementary surface at the valve body shoulder.

70. The hydraulic valve control unit defined in Claim 69 wherein the complementary surface at the valve body shoulder is in the foπn of a truncated conical surface.

71. The hydraulic valve control unit defined in Claim 67 wherein the valve body includes an intemal fluid passageway.

72. The hydraulic valve control unit defined in Claim 67 wherein the valve body includes an extemal fluid passageway.

73. The hydraulic valve control unit defined in Claim 72 wherein the extemal fluid passageway is formed as a trough slot.

74. The hydraulic valve control unit defined in Claim 73 wherein the trough slot is an axial slot.

75. The hydraulic valve control unit defined in Claim 67 wherein the hp is foimed by a swaging tool.

76. The hydraulic valve control unit defined in Claim 67 wherein the hp is formed by swaging a portion ofthe valve housing adjacent the valve bore.

77. The hydraulic valve control unit defined in Claim 76 wherein an annular groove is foimed about the valve housing bore prior to swaging the valve housing portion to form the lip.

78. A method of assembling a hydraulic control unit comprising: foiming a bore in a valve body housing; forming an enlarged diameter portion between first and second end portions of a valve body; sliding a retainer ring over the first end portion ofthe valve body and into engagement with the enlarged diameter portion; inserting the second end portion into the bore ofthe valve body housing; and foπning a lip about the bore into engagement with the retainer ring to secure the retainer ring and valve body in the bore.

79. The method of assembling a hydraulic control unit defined in claim 78 wherein the lip is foimed by swaging the valve body housing.

80. The method defined in claim 79 wherein the lip is formed by cone swaging.

81. A hydrauhc control valve comprising: a valve body having an inner end, an outer end, a fluid passageway, and an outer diameter; a valve body housing having a bore receiving the inner end ofthe valve body; a sleeve having an open end and a closed end, the open end place over the valve body outer end; a retainer ring having a central bore placed over the sleeve and trapping the sleeve between the retainer ring and the sleeve in a sealing manner; and a lip foimed from the valve body housing engaging the retainer ring to secure the valve body, sleeve and retainer ring to the valve body housing.

82. A hydraulic control unit for a vehicular anti-lock brake system comprising; a housing having a control valve bore therein; a sleeve having a closed end and an open end, the open end terminating in an annular flange having an annular gap between the sleeve and the flange; an armature sliceably mounted in the sleeve; a coil suπounding the sleeve for selectively moving the armature; a valve body having an inner end and an outer end, the inner end ofthe valve body received in the bore ofthe housing, the open end ofthe sleeve received over the outer end ofthe valve body; a retainer ring having a central bore, a cylindrical portion, and a radial flange, the retainer ring received over the sleeve so that the cylindrical portion is received in the annular gap between the sleeve and annular flange to trap the sleeve onto the valve body; and a hp formed from the housing engaging the retainer ring to secure the retainer ring, sleeve and valve body to the housing.

83. A control valve for a vehicle anti-lock brake system control unit having a housing with a control valve bore therein, the control valve comprising: a sleeve having a moveable armature therein; a coil surrounding the sleeve for moving the armature, the coil having an inner diameter and an outer diameter; and a valve body having an inner end and an outer end, the outer end attached to the sleeve and the inner end seated within the control valve bore of the housing, the valve body having an outer diameter no greater than the outer diameter ofthe coil such that minimum spacing between multiple control valves in the control unit is not limited solely by the outer diameter of the valve body; a flux ring suπounding the outer end of the valve body; and a casing for securing the coil about the sleeve assembly, the casing being attached to the flux ring.

84. The control valve of claim 83 wherein the outer diameter of the valve body is reduced at the outer end ofthe valve body, the sleeve being open at one end, said open end being slideably received on the reduced portion of the outer end of the valve body and secured thereto, the flux ring being slideably received on said sleeve and having an outer diameter no greater than the outer diameter of the coil.

85. The control valve of claim 84 wherein the flux ring is also slideably received on the outer end of the valve body.

86. The control valve of claim 84 further comprising an electrical control module attached to the coil, the control module, casing , coil and flux ring together forming a sub-assembly, the sub-assembly being placed over the sleeve adjacent the outer end ofthe valve body after the inner end of the valve body is seated within the control valve bore ofthe housing.

87. The control valve of claim 86 wherein the casing, flux ring and valve body are constmcted from a feπous material.

88. The control valve of claim 83 wherein the valve body includes a radially extending retaining flange and the control valve bore of the housing is counterbored to receive said valve body, said housing including means for securing said retaining flange and thereby said valve body fixed within said housing.

89. The control valve of claim 88 further comprising a snap ring for securing the inner end ofthe valve body within the control valve bore ofthe housing.

90. A control valve for a vehicle anti-lock brake system control unit having a housing with a control valve bore therein, the control valve comprising: a sleeve having a moveable armature therein; a coil surrounding the sleeve for moving the armamre, the coil having an inner diameter and an outer diameter, and a valve body having an inner and an outer end, the outer end being attached to the sleeve to provide a sleeve assembly and the inner end seated within the control valve bore ofthe housing, the valve body having an outer diameter no greater than the outer diameter of the coil such that minimum spacing between multiple control valves in the control unit is not limited solely by the outer diameter of the valve body; a flux ring suπounding and being in sliding engagement with said sleeve assembly at a position near the outer end ofthe valve body; and a casing for securing the coil about the sleeve assembly, the casing being in sliding engagement with the flux ring.

91. The control valve of claim 90 wherein the outer diameter of the valve body is reduced at the outer end of the valve body, the flux ring being slideably received on the outer end ofthe valve body and having an outer diameter no greater than the outer diameter ofthe coil.

92. The control valve of claim 90 fiirther comprising an electrical control module attached to the coil, the control module, casing, coil and flux ring together forming a sub-assembly, the sub-assembly being placed over the sleeve and the outer end of the valve body after the inner end of the valve body is seated within the control valve bore of the housing.

93. The control valve of claim 90 wherein the valve body includes a radially extending retaining flange and the control valve bore ofthe housing is counterbored to receive said valve body, said housing including means for securing said retaining flange and thereby said valve body fixed within said housing.

94. The control valve of claim 93 further comprising a snap ring for securing the inner end of the valve body within the control valve bore of the housing.

95. A vehicle anti-lock brake control unit comprising a housing having a plurality of solenoid actuated hydraulic control valves non-threadedly secured in relative fixed axial position within a respective control valve bore therein and extending from a common wall ofthe housing; each control valve including a valve body, a valve stem concentrically aligned with the valve body and non-threadedly secured thereto in fixed relative axial position, said valve stem including an axially extending flow passage therethrough open at each end thereof, an armature concentrically aligned with said valve stem and operatively coupled with said valve stem to control fluid flow through said flow passage when activated by a coil, and a cylindrical sleeve surrounding said armature and secured to said valve body; said sleeve and enclosed armature projecting beyond said housing common wall; said control unit further including an electrical control module including a plurality of individual cylindrical coils received within a respective electrically conductive casing; and each respective casing and coil subassembly including an integral flux ring and being slidably received over a respective one of said control valve sleeves, whereby the electrical control module may be connected and disconnected as a unit from the housing.

96. The anti-lock brake control unit of claim 95 wherein each said valve body includes an outer diameter no greater than the outer diameier of the coil such that minimum spacing between multiple control valves in the control unit is not limited solely by the outer diameter of the valve body.

97. The anti-lock brake control unit of claim 95 wherein each said valve body includes an inner end seated within said control valve bore and an outer end projecting beyond said common wall of the housing; and a flux ring slidably received upon said outer end and being received within said casing.

98. The anti-lock brake control unit of claim 95 wherein the outer diameter of the valve body is reduced at the outer end ofthe valve body, the outer end ofthe valve body adapted to receive the flux ring, the flux ring having an outer diameter no greater than the outer diameter ofthe coil.

99. The anti-lock brake control unit of claim 98 wherein the maximum outer diameter of the valve body is no greater than the outer diameter of the flux ring, coil and casing.

100. The anti-lock brake control unit of claim 96 wherein the casing, flux ring and valve body are constructed from a feπous material.

101. A control valve for a vehicle anti-lock brake system control unit having a housing with a control valve bore therein, the control valve comprising: a cylindrical, relatively thin metal sleeve having a moveable armature therein; a coil assembly suπounding the sleeve for moving the aimature, the coil assembly including a cylindrical electromagnetic coil suπounding said sleeve, a cylindrical casing suπounding said coil, and a cylindrical electrically conductive flux ring having a concentrically located central bore and sunounded by said casing and secured to said casing at one end thereof, said flux ring having an inner diameter defining said central bore and an outer diameter defining the radial outward limit of the flux ring, a cylindrical valve body assembly having an inner end and an outer end, the outer end attached to the sleeve and the inner end seated within the control valve bore of the housing; said sleeve being secured to the valve body at said outer end, said coil assembly being received on said sleeve with said flux ring at said inner diameter being in at least near sliding engagement with said sleeve and being positioned at the outer end of said valve body assembly whereby magnetic flux occurring upon energization of said coil is caused to pass through said flux ring and is confined to the outer end of said valve body assembly.

102. In combination, a control valve and a vehicle anti-lock brake system control unit having a housing with a control valve bore therein, the control valve comprising: a cylindrical, relatively thin metal sleeve having a moveable armature therein; a coil assembly sunounding the sleeve for moving the armature, the coil assembly including a cylindrical electromagnetic coil suπounding said sleeve, a cylindrical casing suπounding said coil, and a cylindrical electrically conductive flux ring having a concentrically located central bore and sunounded by said casing and secured to said casing at one end thereof, said flux ring having an inner diameter defining said central bore and an outer diameter defining the radial outward limit of the flux ring, a cylindrical valve body assembly having an inner end and an outer end, the outer end attached to the sleeve and the inner end seated within the control valve bore ofthe housing; said sleeve being secured to the valve body at said outer end; an electrical control module attached to the coil, the control module, casing, coil and flux ring together forming a sub-assembly, the sub-

SUBSπrUTE SHEET (RULE 26) assembly being placed over the sleeve and the outer end ofthe valve body after the inner end of the valve body is seated within the control valve bore ofthe housing; said sub-assembly being received on said sleeve with said flux ring at said inner diameter being in at least near sliding engagement with said sleeve and being positioned at the outer end of said valve body assembly whereby magnetic flux occurring upon energization of said coil is caused to pass through said flux ring and is confined to the outer end of said valve body assembly.

103. An anti-lock brake control unit for a braking system of an automotive vehicle having a master brake cylinder providing a pressured brake fluid to the slave cylinders of the brake assemblies of each wheel in response to the depression of a brake actuator by an operator ofthe vehicle, said control unit comprising: an isolation valve for at least one wheel ofthe automotive vehicle, said isolation valve having an intemal portion and extemal portion and a radial flange intermediate said intemal and extemal portions, said extemal portion including an armature displaceable in response to a magnetic field to change said isolation valve from an open state to a closed state; a hold/dump valve for said at least one wheel ofthe automotive vehicle, said hold/dump valve having an intemal portion, an extemal portion and a radial flange intermediate said intemal and extemal portions, said extemal portion including an armature displaceable in response to a magnetic field to change said hold/dump valve from a closed state to an open state; a valve body housing having a plurality of cylindrical cavities in which said intemal portions of said isolation and hold/dump valves are respectively received, each cylindrical cavity further having a counterbore foiming a shoulder at the bottom thereof forming a seat for said radial flanges of said isolation and hold/dump valves and a swaged annular lip extending over the edge of the radial flange of each ofthe isolation and hold/dump valves, said swaged annular lip mechanically securing said radial flange to said shoulder and to said valve body housing and foiming at least a secondary fluid seal between said radial flange and said valve body housing, said valve body further having at least one inlet port for receiving pressurized brake fluid from the master cylinder, a plurality of outlet ports for transimtting pressurized brake fluid to the salve cylinders ofthe brake assemblies for each wheel, at least one low pressure accumulator, and intemal passageways connecting said at least one inlet port to the inputs of said isolation valves, for connecting the outputs of said isolation valves to the inputs of an associated hold dump valve and to an associated one of said outlet ports and for connecting the output of each hold/dump valve to said at least one low pressure accumulator and for connecting said at least one low pressure accumulator to an input of said pump and an output of said pump to said inputs of said isolation valves; each of said isolation valves including:

(a) a cylindrical valve body having a first end and a second end, said radial flange disposed intermediate said first and second ends, an axial fluid passageway provided through said valve body, a valve seat provided at the end of said coaxial bore adjacent to said first end, and at least one offset fluid passageway providing a fluid passage from said one end of said valve body to a location intermediate said radial flange and said second end of said valve body;

(b) a cylindrical sleeve having a closed end and an open end, said open end being sealingly attached to said first end of said body; (c) an armature disposed in said cylindrical sleeve resiliently biased away from said valve seat; and

(d) a valve member attached to said armature in alignment with said valve seat, said valve member operative to engage said valve seat blocking a fluid flow from said coaxial fluid passagway to said offset fluid passageway when said aimature is displaced towards said valve body by the magnetic field generated by the associated solendoid coil assembly when energized; said valve member being made from a substantially non- deformable ceramic material.

104. The control unit of claim 103 wherein said ceramic material is selected from a group of ceramic materials consisting of zirconia, silicon carbide, alumina oxide ruby, sapphire and silicon nitride.

105. The control unit of claim 104 further including a coil integrated module mounted to said valve body housing, said coil integrated module having a solenoid coil assembly, including a flux ring, for each isolation valve and each hold/dump valve mounted in said valve body housing, each flux ring of said solenoid coil assembly circumscribing a selected one of said extemal portions of said isolation and hold/dump valves and operative, when energized, to produce a magnetic field sufficient to displace said armature in said selected one isolation and hold/dump valves.

106. The control unit of claim 105 wherein each said hold/dump valve includes:

(a) a cylindrical body having a first end and a second end, said cylindrical valve body having said radial flange disposed intermediate said first and second ends, a coaxial fluid passage provided through said valve body, a valve seat provided at the end of said coaxial fluid passage adjacent to said first end, and at least one offset fluid passageway passing from said one end of said valve body and exiting said valve body at a location intermediate said radial flange and said second end of said valve body; (b) a cylindrical sleeve having a closed end and an open end attached to said valve body;

(c) an armature disposed in said cylindrical sleeve intermediate said closed end and said valve seat, said aimature resiliently biased towards said valve seat;

(d) a valve member attached to said armature on the side adjacent to said first end, said valve member engaging said valve seat blocking a fluid flow between said coaxial fluid passage and said offset fluid passageway, said valve member displaceable away from said valve body by the magnetic field generated by the associated solenoid coil assembly when energized.

107. The control unit of claim 106 wherein said valve member of said hold dump valve is made from a substantially non-deformable ceramic material.

108. The control unit of claim 107 wherein said valve member of said hold/dump valve is a ball made from said ceramic material.

109. The control unit of claim 108 wherein said ceramic material is selected from a group of ceramic materials consisting of zirconia, silicon carbide, alumina oxide, ruby, sapphire and silicon nitride.

110. A valve mountable in a valve housing having a valve cavity and a counterbore forming a flange shoulder comprising: a cylindrical valve body receivable in the valve cavity, said valve body having a first end, an opposite end and a radial flange intermediate said first and opposite ends receivable in said counterbore and seatable on said flange shoulder; a concentric fluid passageway provided in said valve body extending from said first end to said opposite end, said concentric fluid passageway having a valve seat provided adjacent to said first end; an offset passageway provided in said valve body extending from said first end at a location radially offset from said concentric fluid passageway and exiting said valve body at a location intermediate said radial flange and said opposite end; a cylindrical sleeve having a closed end, said cylindrical sleeve sealingly attached to said first end of said valve body and extending concentrically therefrom; an armature slidably disposed in said cylindrical sleeve; means for biasing said armature relative to said valve body; and a ball valve attached to said armature in alignment with said valve seat, said ball valve blocking a fluid flow in said concentric fluid passageway when said ball valve is engaged with said valve seat; said ball valve being a non-deformable ceramic material.

111. The valve of claim 110 wherein said non-deformable ceramic material is selected from a group of ceramic materials consisting of zirconia, silicon carbide, alumina oxide, mby, sapphire and silicon nitride.

112. A control valve for a vehicle anti-lock brake system control unit having a housing with a control valve bore therein, the control valve comprising: a sleeve having a moveable armature therein; a coil suπounding the sleeve for moving the armature, the coil having an inner diameter and an outer diameter; and a valve body having a first end and a second end, the first end being disposed within the sleeve and the second end seated within the control valve bore of the housing, an axial first fluid passageway provided through said valve body, a valve seat provided at the end of said coaxial bore adjacent to said first end, and at least one offset fluid passageway providing a second fluid passage; said armature being disposed in said sleeve and resiliently biased in one direction relative to said valve seat; and a valve member attached to said armature in alignment with said valve seat, said valve member operative in one direction to engage or disengage said valve seat blocking a fluid flow from said coaxial fluid passageway to said offset fluid passageway when said armature is displaced in said one direction relative to said valve body by the magnetic field generated by an associated solenoid coil assembly when energized; said valve member being made from a substantially non- deformable ceramic material.

113. The control unit of claim 112 wherein said ceramic material is selected from a group of ceramic materials consisting of zirconia, silicon carbide, alumina oxide, mby, sapphire and silicon nitride.