ELECTROMAGNETIC SOLENOID VALVE FOR HYDRAULICALLY ACTUATED BRAKE SYSTEMS WITH SLIP CONTROL

Abstract: An electromagnetic solenoid valve (10) for use with hydraulically actuated brake systems includes a valve housing (12) having a stepped bore (14) therein defining an axis (16) and a generally cylindrical valve sleeve (38) with an open end and an opposite closed end, with the open end disposed over a first portion (18) of the bore (14). A solenoid core (40) is fixed within the void (39). A solenoid armature (36) is slidably disposed in the void (39). A valve needle (34) engages the armature (36) for movement between open and closed positions. A solenoid coil (54) is disposed within the housing (12) in a second part (20) of the bore (14) and circumscribes the sleeve (38). A valve cover (60) is located at an end (22) of the housing (12), closing the bore (14).

Description: ELECTROHAGMETIC SOLENOID VALVE FOR HYDRAULICALLY ACTUATED BRAKE SYSTEMS WITH SLIP CONTROL BACKGROUND OF THE INVENTION This invention is related to electromagnetic solenoid valves and more particularly to such valves as employed in hydraulically actuated brake systems with slip control. In a known type of electromagnetic solenoid valve configuration, a valve cover closes one end of a bore in a valve housing. The valve cover has a portion which extends down into the housing bore. A bore in the cover, together with the bore in the housing, defines an axial void. A valve needle and a solenoid armature, joined for unitary movement, are slidably disposed in the void. A solenoid coil surrounds part of the cover, with the cover serving as the solenoid core. A disadvantage of the above described configuration is that it provides an opportunity for the introduction of metal shavings or chips and other unwanted debris to enter the sliding portion of the valve during assembly. The valve is particularly vulnerable to such contamination after the valve needle and armature have been installed, but before the valve cover have been installed. Even the installation of the valve cover presents a risk of introducing unwanted debris. The valve cover may be carrying chips generated during its forming. It is therefore an object of the invention to provide a reconfigured valve which is less vulnerable to the introduction of unwanted debris introduced in the course of valve assembly. Such debris can have a deleterious effect on the performance of the electromagnetic solenoid valve. It is therefore desired to provide a valve protecting the sliding portions of the valve from such debris. SUWttRY OF THE IHVBHTIOH An electromagnetic solenoid valve for use with hydraulically actuated brake systems is disclosed comprising a valve housing having a stepped bore therein defining an axis and a generally cylindrical valve sleeve, with an open end portion and a closed end portion, with the open end portion disposed over a first portion of the bore to define a void. A solenoid core is fixed within the void. A solenoid armature is slidably disposed in the void. A valve needle engages the armature for movement between open and closed positions. A solenoid coil is disposed in the void. A valve cover is located at an end of the housing, closing the bore. The disclosed valve configuration is much more reliable in its operation than similar valves having a one piece cover at an end of the housing which acts as the core, the sleeve and the cover of the present invention. The sleeve of the present invention acts as a shield over the sliding parts of the solenoid valve preventing the introduction of metal chips and other debris which may be potentially introduced into the valve during the latter stages of valve assembly and interfere with the operation of the valve. DESCRIPTION OF THE DRAWINGS The figure is a cross sectional view of one embodiment of a solenoid valve according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An electromagnetic solenoid valve 10 has a valve housing 12 with a stepped bore 14. The bore 14 defines an axis 16 on which are centered a plurality of portions of the bore 14. The bore has a first portion 18 with a first diameter, a second portion 20 with a second diameter larger than the first diameter, and a third portion 22 with a third diameter larger than the second diameter. The first portion 18 of the bore opens into the second portion 20 which opens into the third portion 22 of the bore 14. The third portion 22 of the bore 14 is at a first end portion 24 of the valve housing 12. The first portion 18 of the bore 14 is distal to the first end portion 24 of the valve housing 12. A first hydraulic fluid duct 26 passes from a second end portion 28 of the housing 12 into the first portion 18 of the bore 14. A second hydraulic fluid duct 30 passes from a side 31 of the valve housing 12 to the first portion 18 of the bore. A valve seat 32 is disposed at a bottom of the first portion 18 of the bore 14, over the first hydraulic fluid duct 26. A valve needle 34 is disposed in part in the first portion 18 of the bore 14 along the bore axis 16. A tip of the valve needle 34 operably engages the valve seat 32 in a closed position shown in the figure, thereby blocking fluid communication between the first hydraulic fluid duct 26 and the second hydraulic duct 30. A solenoid armature 36 formed of magnetically permeable material is fixed to the valve needle 34. A plurality of circumferential grooves on the valve needle 34 are engaged by the armature 36 such that the needle 34 and the armature 36 move as a unit. A valve sleeve 38 is substantially bullet shaped, or cylindrical, with a closed end portion and an opposed open end portion. The valve sleeve 38 is disposed over the first portion 18 of the bore 14 to define a void 39 therein. The valve needle 34 and the solenoid armature 36 are slidably disposed in the void 39. A solenoid core 40, also formed of magnetically permeable material, is disposed at the closed end portion of the valve sleeve 38. The solenoid core 40 has a central stepped bore 42 passing therethrough. A return spring 44 is disposed in the stepped bore 42 of the core 40 with one end disposed against a shoulder in the core 40 defined by the stepped bore 42, and a second end disposed against the solenoid armature 36. An upper end of the valve needle 34 extending beyond the armature 36 is disposed in the stepped bore 42 and surrounded by the return spring 44. The return spring 44 biases the armature 36 away from the core 42, thereby pressing the tip of the valve needle 34 against the valve seat 32. With the valve needle 34 seated, the core 42 and armature are separated by a gap 45. The core 40 has a circumferential groove 46 therearound. The valve sleeve 38 has at least one dimple 48 deflecting into the circumferential groove 46 to retain the core 40 at the end of the sleeve 38. A bushing 50 is installed in the valve housing 12 at a bottom of the first portion 18 of the bore 14. The bushing 50 has an inside diameter substantially equal to the diameter of the first portion 18 of the bore 14. An outer surface of the bushing 50 defines an upwardly directed frustoconical surface 52. The open end portion of the valve sleeve 38 has a shape complimentary to that of the frustoconical surface 52, and is disposed thereover. A portion of the housing 12 around the bushing 50 and the sleeve 38 is cold formed to provide a lip over the open end portion of the sleeve 38. The lip presses against the open end portion of the sleeve 38, maintaining the sleeve in engagement with the frustoconical surface 52 of the bushing 50. It is readily apparent that the sliding parts of the electromagnetic solenoid valve 10 are disposed within the void 39 formed between the sleeve 38 and the housing 12. The sleeve 38 provides the parts disposed therein with a high degree of protection from any subsequently introduced debris, such as metal chips or the like, with may potentially be introduced during subsequent assembly operations. Such debris can fall between the armature 36 and the first bore portion 18, causing the armature 36 to bind. An annular solenoid coil 54 is placed over the valve sleeve 38, in the second portion 20 of the bore 14. The term coil 54 includes any frame or structure in addition to coil windings. A wire terminal 56 of the coil 54 extends from the coil 54 and passed through slot 58 in the first end portion 24 of the housing 12 to an outside of the housing 12. A valve end cover 60 is disposed in the third portion 22 of the bore 14. The end cover 60 is retained in the housing 12 by cold forming the first end portion 24 of the housing 12 to form a lip 62 disposed over an outer circumference of the cover 60. The cover 60 has a bottom surface including an annular surface 64 engaging both a shoulder of the housing 12 and an upper surface of the coil 54. Projecting axially downward from the annular surface 64 is a plug portion 68 of the cover 60. The plug portion 66 extends into the solenoid coil 54, helping to center the coil in the second portion 20 of the bore 14. The plug portion 66 has a hemispherical seating surface 68 engaging the closed end of the valve sleeve 38 which has a similar shape. The cover 60 helps retain both the annular magnetic coil 54 and the sleeve 38 in the valve 12. The valve 10 is a normally closed valve. The return spring 44 biases the needle to the closed position. Energization of the solenoid valve causes the armature 36 and the needle 34 to be drawn toward the core 40 to an open position in which the tip of the needle 40 is spaced from the seat 32. In known valves over which the present invention offers an improvement, the closed end sleeve 38 is not provided, and the cover 60 and core 40 are formed as an integral piece. The presently disclosed valve introduces extra parts and assembly operations into the fabrication of the valve, which would typically be expected to result in a decrease in valve reliability. However, the net effect on valve reliability is just the opposite, with the shielding of the sliding needle and armature providing an appreciable increase in the reliability of valve operation. Other aspects, objects, and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.

Claims: CLAIMS We claim: 1. An electromagnetic solenoid valve for use with hydraulically actuated brake system comprising: a valve housing having a stepped bore therein defining an axis; a generally cylindrical valve sleeve with an open end portion and an opposed closed end portion with the open end portion disposed over a first portion of the bore to define a void therein; a solenoid armature slidably disposed within the void for axial movement therein; a valve needle engaging the solenoid armature for movement therewith between open and closed positions; a solenoid core disposed in the void; a spring operably disposed between the armature and the core; an annular solenoid coil disposed within the housing and circumscribing the sleeve; and a valve cover disposed at an end portion of the housing thereby closing the bore. 2. An electromagnetic solenoid valve as claimed in claim 1 wherein the cover engages the solenoid coil. 3. An electromagnetic solenoid valve as claimed in claim 1 wherein the cover engages the sleeve. 4. An electromagnetic solenoid valve as claimed in claim 1, wherein the cover has an annular engaging surface engaging the solenoid core, and a recess which engages the sleeve. 5. An electromagnetic solenoid valve for use with kydraulically actuated brake system comprising: a valve housing having a stepped bore entering the bousing from a first end portion of the housing and defining therein an axis of the bore and both a first portion of the bore end a larger diameter second portion of the bore, wherein the second portion of the bore is more proximate to the first end portion of the housing than the first portion of the bore; a generally cylindrical valve sleeve with an open end portion and an opposed closed end portion with the open end portion disposed over the first portion of the bore to define a void therein; a solenoid armature slidably disposed within the void for axial movement therein; a valve needle engaging the solenoid armature for ■ovement therewith and operably engaging a valve seat within the valve housing; a solenoid core fixedly disposed in the void; a spring operably disposed between the armature and the core; an annular solenoid coil disposed within the second part of the stepped bore of the housing and circumscribing the sleeve; and a valve cover engaging the housing at the first end portion of the housing and sized to close the bore. 6. An electromagnetic solenoid valve as claimed in claim 5 wherein the cover engages the solenoid coil. 7. An electromagnetic solenoid valve as claimed ir claim 5 wherein the cover engages the sleeve. 8. An electromagnetic solenoid valve as claimed in claim 5, wherein the cover has an annular engaging surface engaging the solenoid core, and a recess which engages: the sleeve.

Inventors: BURRELL GARY R, KAYSER MICHAEL, KINKADE STUART, BURRELL, GARY, R., KAYSER, MICHAEL, KINKADE, STUART
Applicants: ITT, ITT INDUSTRIES, INC.
Application year: 1995
Main classification: B60T8
IPC codes: B60T8