Patent Application
20220049673
The present disclosure relates generally to stator design and operation in electrical actuators, and more particularly to a valve assembly having an electrical actuator stator shaped to limit high velocity flows of fluid displaced as a result of movement of the armature in the valve assembly.
A great many different pump designs are used for transferring and pressurizing fluids. In the context of fuel systems, such as for internal combustion engines, electronically-controlled, high-pressure fuel pumps are commonplace and used to pressurize a fuel such as diesel fuel for injection into an engine cylinder. Highly pressurized fuel injection strategies have been shown to be effective for reduced emissions operation. In one design, a high pressure fuel pump feeds a so-called common rail that provides a fluid reservoir storing a quantity of pressurized fuel for delivery to a plurality of fuel injectors. In other designs, fuel pumps are associated individually with fuel injectors, and are known as unit pumps.
To achieve a high level of control of moving parts within such pumps, electrical actuators such as solenoid actuators are used to control valve positioning and fluid connections. Solenoids produce a magnetic field when electrical current is applied that can generate local forces with sufficient energy to actuate components within the fuel system hardware. Engineers have experimented with a wide variety of different electrical actuator and pump designs over the years. With the drive toward ever-increasing pressure and control over fuel injection amount, fuel injection rate and other properties, the electrical actuators and associated valve components within fuel pumps tend to move relatively rapidly and can impact valve seats, stops, or other surfaces with relatively high forces. One example fuel pump design is known from U.S. Pat. No. 5,743,238 to Shorey et al. In the configuration shown in Shorey et al., an electrical actuator is used to control a valve that apparently varies position to alternately allow or inhibit fuel flow to a pumping chamber.
In one aspect, a valve assembly includes a valve member operatively associated with a valve seat, with the valve member being movable along a valve central axis between a first open position at which the valve member is spaced from the valve seat and a second closed position at which the valve member engages the valve seat to seal an opening of the valve assembly. An electrical actuator includes a stator and an armature coupled to the valve member. The stator includes an annular outer stator portion and an annular inner stator portion, and an annular channel formed radially between the outer stator portion and the inner stator portion. A first radial channel extends through the annular outer stator portion between an outer surface of the outer stator portion and the annular channel. At least one second opening is disposed in the annular outer stator portion on an opposite half of the stator from the first radial channel. The stator is magnetically symmetrical along a line bisecting the first radial channel and perpendicular to the central axis. A winding and terminal assembly includes an electrically conductive winding disposed within the annular channel and between the outer stator portion and the inner stator portion and electrically conductive terminals electrically connected to the winding. A portion of the winding and terminal assembly extends through the first radial. The armature includes an armature plate defining an armature center axis, with the armature center axis being co-linear with the valve central axis and being movable between a rest position and an activated position to vary a position of the valve member, in response to a change to an energy state of the electrical actuator. The armature plate includes a top armature surface facing the stator.
In another aspect, a valve assembly includes a valve member operatively associated with a valve seat, with the valve member being movable along a valve central axis between a first open position at which the valve member is spaced from the valve seat and a second closed position at which the valve member engages the valve seat to seal an opening of the valve assembly. An electrical actuator includes a stator and an armature coupled to the valve member. The stator includes an annular outer stator portion and an annular inner stator portion, and an annular channel formed radially between the outer stator portion and the inner stator portion. A first radial channel extends through the annular outer stator portion between an outer surface of the outer stator portion and the annular channel. At least one second opening is disposed in the annular outer stator portion on an opposite half of the stator from the first radial channel. The stator is magnetically symmetrical along a line bisecting the first radial channel and perpendicular to the central axis. A winding and terminal assembly includes an electrically conductive winding disposed within the annular channel and between the outer stator portion and the inner stator portion and electrically conductive terminals electrically connected to the winding. A portion of the winding and terminal assembly extends through the first radial channel. An insert-molded body extends about the stator and into each of the first radial channel and the at least one second opening. The armature includes an armature plate defining an armature center axis, with the armature center axis being co-linear with the valve central axis and being movable between a rest position and an activated position to vary a position of the valve member, in response to a change to an energy state of the electrical actuator. The armature plate includes a top armature surface facing the stator.
In still another aspect, a pump includes a pump housing, and a pumping element movable between a retracted position and an advanced position within a pumping chamber formed in the pump housing. The pump further includes a valve assembly for controlling a flow of a fluid to or from the pumping chamber. The valve assembly includes a valve member operatively associated with a valve seat, with the valve member being movable along a valve central axis between a first open position at which the valve member is spaced from the valve seat and a second closed position at which the valve member engages the valve seat to seal an opening of the valve assembly. An electrical actuator includes a stator and an armature coupled to the valve member. The stator includes an annular outer stator portion and an annular inner stator portion, and an annular channel formed radially between the outer stator portion and the inner stator portion. A first radial channel extends through the annular outer stator portion between an outer surface of the outer stator portion and the annular channel. At least one second opening is disposed in the annular outer stator portion on an opposite half of the stator from the first radial channel. The stator is magnetically symmetrical along a line bisecting the first radial channel and perpendicular to the central axis. A winding and terminal assembly includes an electrically conductive winding disposed within the annular channel and between the outer stator portion and the inner stator portion and electrically conductive terminals electrically connected to the winding. A portion of the winding and terminal assembly extends through the first radial channel. The armature includes an armature plate defining an armature center axis, with the armature center axis being co-linear with the valve central axis and being movable between a rest position and an activated position to vary a position of the valve member, in response to a change to an energy state of the electrical actuator. The armature plate includes a top armature surface facing the stator.
Referring to
Plunger 14 is the only plunger visible in the section plane of
A spring-biased outlet valve 19 blocks pump outlet 22, but opens in response to sufficient pressure to enable fluid communication between plunger cavity 16 and a common rail or other component to be supplied with pressurized fuel. Other valve positioning and operating strategies could be used. Valve member 26 could include a control valve that controls the position of another valve, for example. Valve assembly 24 also includes an electrical actuator 30, the operation and unique configuration of which is further discussed herein.
Electrical actuator 30 includes a stator 32 positioned within or coupled with pump housing 12, and an armature 44. Armature 44 may be coupled to valve member 26, and in an implementation can include an armature pin 47 that is attached to and/or formed integrally with valve member 26. Valve member 26 and/or armature pin 47 extends through armature plate 46. Armature 44 and armature plate 46 are terms used interchangeably herein. Changing an energy state of electrical actuator 30 can cause armature 44 to move according to well-known principles relative to stator 32. A change to the energy state will typically include electrically energizing electrical actuator 30, however, embodiments are contemplated in which a change to the energy state includes deenergizing electrical actuator 30. Increasing an energy state of electrical actuator 30 from a first energy state to a higher energy state, or decreasing an energy state from a higher energy state to a lower energy state, could also be understood as changing an energy state as contemplated herein.
In the illustrated embodiment, stator 32 includes an outer stator portion 34 having an annular shape, and an inner stator portion 35 also having an annular shape. Outer stator portion 34 and inner stator portion 35 can be concentrically arranged with one another, and centered on pump housing longitudinal axis 13, however, the present disclosure is not thereby limited. An annular channel 36 is formed between outer stator portion 34 and inner stator portion 35. In the illustrated embodiment, electrical actuator 30 includes a solenoid electrical actuator having a winding 38 that is positioned within or at least partially within channel 36. Winding 38 includes electrically conductive metallic material in a generally conventional manner. Electrical actuator 30 may also include a non-metallic over-molding 40 encasing winding 38. An electrical plug 42 is coupled with pump housing 12 to provide for electrical connections with winding 38.
Stator 32 also includes a stator end face 52 (“stator face 52”) that faces armature 44 and is formed in part by annular end faces (not numbered) of each of outer stator portion 34 and inner stator portion 35 that are positioned in a common plane, and also in part, in embodiments, by winding 38. Over-molding 40 thus forms an exposed portion of stator face 52, the significance of which will be apparent from the following description.
Armature plate 46 defines armature center axis 48. At the state depicted in
Armature plate 46 includes a top armature surface 50 facing stator 32, a bottom armature surface 54, and an outer perimetric surface 56 extending circumferentially around armature center axis 48 and axially between top armature surface 50 and bottom armature surface 54. Referring
Referring also to
In the illustrated embodiment, an armature cavity 66 is formed in pump housing 12 to accommodate the motion of armature 44. During operation of the pump 10, the armature cavity 66 will typically be filled with the working fluid transitioned through pump 10, although of course other fluids could be used. When armature 44 is moved from its rest position, approximately as depicted in
It has been observed that the squeezing of fluid between armature 44 and stator 32, and particularly between armature 44 and slot 72, can result in a velocity and energy of the fluid that is sufficient, at least over time, to erode or otherwise damage over-molding 40. The inwardly stepped-up profile of top surface 50 ameliorates these erosive phenomena by providing an easier escape route for the displaced fluid. As noted above, top surface 50 includes raised surface 58 and lower surface 60. In earlier designs lacking an inwardly stepped-up profile no such escape route for fluid was provided. In
It will be recalled that moving armature 44 to the activated position can include tilting armature 44, ultimately such that a top surface 50 of armature 44 is tilted relative to stator face 52. It is believed that the tilting of armature 44, and some similar armatures, can cause or compound the phenomena potentially leading to erosion as described herein. It can be seen that the known armature profile 160 could result in armature plate 46 contacting stator 32 or nearly contacting stator 32 and limiting or preventing entirely a radially outward flow of fluid, at least in the vicinity of the point(s) of contact or near-contact between armature 44 and stator face 52, when armature 44 reaches the activated position. As a result, fluid being displaced could be expected to be redirected inwardly, circumferentially, and upwardly into slot 72, in the process being accelerated to the point that a jet(s) of high velocity fluid can damage the relatively soft over-molding 40.
Turning now to
Magnetic flux density tends to weaken nonlinearly in directions radially outward from the center of a solenoid coil. For this reason, removing or limiting the use of material that is relatively more radially outward in an armature according to the present disclosure tends to have only a relatively mild effect, if any, on the magnitude of electromagnetic force applied to armature 44 when electrical actuator 30 is energized. It will be appreciated that various modifications to the geometry, proportions, and relative dimensions of armature plate 46 as depicted in
In the illustrated embodiment, electrical actuator 30 includes a solenoid electrical actuator having a winding 38 that is positioned within or at least partially within channel 36. Winding 38 includes electrically conductive metallic material in a generally conventional manner. Electrical actuator 30 may also include a non-metallic over-molding 40 encasing winding 38. An electrical plug 42 is coupled with pump housing 12 to provide for electrical connections with winding 38.
Stator 32 also includes a stator end face 52 (“stator face 52”) that faces armature 44 and is formed in part by annular end faces (not numbered) of each of outer stator portion 34 and inner stator portion 35 that are positioned in a common plane, and also in part, in embodiments, by winding 38. Over-molding 40 thus forms an exposed portion of stator face 52, the significance of which will be apparent from the following description.
In order to reduce or eliminate tilting of the armature 44 including armature plate 46 and thus further reduce or eliminate wear along the lower surface of the insulation 40 surrounding the windings 38, an alternate embodiment of the electrical actuator 130 depicted in
Referring first to
A first radial channel 181 extends through the outer stator portion 134 from the annular channel 136 to the outer surface 137 of the outer stator portion. The first radial channel 181 may also extend upwards through the upper portion 180. The first radial channel 181 provides a passage for a portion of the winding and terminal assembly 187 to pass through, as described below.
A second radial channel 182 extends through the outer stator portion 134 from the annular channel 136 to the outer surface 137 of the outer stator portion. The second radial channel 182 may also extend upwards through the upper portion 180. In an embodiment, the second radial channel may be identical to the first radial channel 181. Further, the second radial channel 182 may be disposed diametrically opposite the first radial channel 181. In other words, the first and second radial channels 181, 182 are on opposite sides of the stator central axis 133 and aligned along a line 184 that bisects the centers of both channels and also crosses through or intersects with and is perpendicular to the central axis.
In an embodiment, the upper portion 180 of the stator 132 may include openings 185 configured to assist in the assembly of the actuator 130. In some embodiments, the openings 185 may be diametrically opposed and lie along a line 186 perpendicular to line 184. In such case, the stator 132 is symmetrical about the bisecting line 184 through the first and second radial channels 181, 182. In other embodiments, the openings 185 may be slightly offset from the line 186. In such case, the lower surface of the stator 132 is symmetrical about the bisecting line 184 through the first and second radial channels 181, 182. In other embodiments, the openings 185 may be omitted. Stator 132 may be formed of any desired magnetic material, such as one having a high magnetic permeability. In one embodiment, the stator 132 may be formed of a soft magnetic composite material and be formed using a powdered metallurgy or molding process. Other materials and processes for forming stator 132 are contemplated.
The winding and terminal assembly 187 includes a bobbin 188 about which coil 38 (
A non-magnetic barrier 190 may be provided between the stator 132 and the armature spring 68 to form a magnetic barrier and prevent the spring from being attracted to the stator and causing wear. The barrier 190 may be formed of any desired material. In one embodiment, the barrier 190 may be formed of stainless steel and may be formed of multiple components that may be machined, stamped, and/or extruded. Other materials and manufacturing processes are contemplated.
Over-molded body 192 may be formed about the stator 132, the winding and terminal assembly 190, and the non-magnetic barrier 190. The body 192 is similar to that depicted in
After the over-molded body 192 is formed about the stator 132, the winding and terminal assembly 190, and the non-magnetic barrier 190, the connector 42 may be secured to the body 192 with the terminals 189 extending into a cavity in the connector.
Referring to
Other manners of achieving magnetic symmetry of the stator 132, and particularly along the lower surface of the stator 132, are contemplated. For example, rather than positioning the second radial channel 182 along the line 184, the second radial channel may be replaced by other openings in the stator to reduce the magnetic flux by an amount equal to or substantially equal to the reduction caused by the existence of the first radial channel 181. In an example depicted in
The positions and dimensions of the openings 195 may be adjusted to balance the magnetic flux on opposite sides of the lines 184 and 185. In an example, each pair of openings 195 and 196 may be configured as radial channels that are identical to the first radial channel 181. In such case, each of the first radial channel 181 and the pair of radial channels may be disposed circumferentially 120 degrees apart along the outer surface of the stator 132 in order to achieve magnetic symmetry of the stator.
Regardless of the shape and position of the openings 195 and 196, the over-molding material used to form the body 192 will fill the openings.
It will be appreciated by one skilled in the art that since the openings 185 are in the upper portion 180 of the stator 132, the impact on the magnetic flux relative to the armature plate 46 as a result of any asymmetry caused by the openings 185 will be reduced.
The actuator 130 may be used with an armature plate having a top surface with any desired configuration. In one embodiment, the top surface 50 may be stepped as depicted in
Referring to the drawings generally, operating valve assembly 24 can include changing an energy state of electrical actuator 30 as discussed herein, and moving armature 44 from the rest position toward stator 32 in response to the change to the energy state of electrical actuator 30. Armature 44 will move toward the activated position and be stopped at the activated position, such as by contacting valve member 26 with valve seat 28, although depending upon manufacturing tolerances, component wear, and the degree of tilting of armature 44, raised surface 58 could also contact stator face 52. At the activated position, lower surface 60 forms gap 70 such that fluid can be displaced from between armature 44 and stator 32 by way of gap 70. Valve 26 is moved in the manner described herein to vary fluid connections to pumping chamber or plunger cavity 16 in pump 10. When electrical actuator 30 is deenergized, armature 44 can move back toward the rest position under the influence of return spring 68.
Referring now to
During operation of the actuator 130 of
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawing and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
