Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/40—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition comprising an additional fluid circuit including fluid pressurising means for modifying the pressure of the braking fluid, e.g. including wheel driven pumps for detecting a speed condition, or pumps which are controlled by means independent of the braking system
  • B60T8/4031—Pump units characterised by their construction or mounting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/0404—Details or component parts
  • F04B1/0408—Pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/0404—Details or component parts
  • F04B1/0452—Distribution members, e.g. valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/10—Valves; Arrangement of valves
  • F04B53/12—Valves; Arrangement of valves arranged in or on pistons
  • F04B53/125—Reciprocating valves
  • F04B53/127—Disc valves
  • F04B53/128—Annular disc valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/16—Sealings between relatively-moving surfaces
  • F16J15/164—Sealings between relatively-moving surfaces the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/56—Other sealings for reciprocating rods

Definitions

• This invention relates in general to brake systems for vehicles and in particular to a pump assembly with a combination reciprocating high-pressure seal and fluid inlet check valve for use within brake systems.
• a supply of hydraulic fluid for the vehicle brakes is modulated by a hydraulic control unit.
• Various hydraulic pumps may be employed to selectively supply hydraulic fluid to the vehicle brakes.
• Several hydraulic pump designs are known.
• U.S. Patent No. 4,556,261 to Farr discloses a prior art pump and skid sensing assembly for a vehicle hydraulic anti-skid braking system, as shown in Figs. 1 and 2.
• the assembly comprises a housing 1 incorporating a hydraulic pump 2, and a solenoid-operated valve assembly 3. Only the operation of the pump 2 will be described herein, as the operation of the rest of the anti-skid braking system is not relevant to the present invention.
• the pump 2 includes a plunger 10, which reciprocates within a stepped bore 11 in the housing 1.
• the plunger 10 is engageable with a drive mechanism comprising a ring 12 rotatable on a shaft 4.
• the plunger 10 carries an 'O' ring seal 18 and a lip seal 19.
• the seals 18 and 19 are disposed on opposite sides of a passage 20 leading to the valve 3.
• the seals 18 and 19, the plunger 10, and the bore 11 define a chamber 22.
• a reservoir 35 supplies the chamber 22 with fluid.
• the seal 19, which is illustrated in detail in FIG. 2, comprises an annular ring of elastomeric material, which is received in an annular groove 25 in the plunger 10.
• the groove 25 is parallel sided and is of an axial length greater than the thickness of the seal 19.
• Opposite faces 26 and 27 of the seal being provided with at least one diametrical slot 28 which communicates with one or more passages 29 in the inner peripheral edge of the seal 19.
• the planar face 26 is adapted to seal against the adjacent, inner, face25a of the groove 25 to prevent flow from the secondary chamber 22 into the reservoir35 when the seal 19 is in a first position relative to the plunger 10.
• the face 25a is formed by an inlet flange 40 of the plunger 10.
• the face 26 of the seal 19 and the inlet flange 40 form a check valve assembly forseparating the secondary chamber 22 and the reservoir 35.
• the seal 19 is rather complex in that it contains at least one radial slot 28 and at least one longitudinal passage 29 formed therethrough to permit fluid flow past the check valve assembly when the face 22 of the seal 19 abuts the adjacent side wall of the groove 25.
• An inlet passageway 41 is formed by the inlet flange 40 and the housing 1.
• a retaining flange 42 and the housing 1 form an outlet passageway 43 of the check valve assembly.
• the longitudinal passage 29 is in fluid communication with the inlet passageway 41, and the longitudinal passage 29 is in fluid communication with the radial slot 28.
• the radial slot 28 is in fluid communication with the outlet passageway 43, such that the check valve assembly is in an open position and the chamber 22 and the reservoir 35 are communicably connected. Therefore, the radial slot 28 allows the longitudinal passageway 29 to be in indirect fluid communication with the outlet passageway 43.
• the radial slot 28 has an outer radius that extends beyond the outer radius of the longitudinal passage 29 taken about a longitudinal axis of the plunger 10.
• the seal 19 seals against the adjacent face of the groove 25 so that fluid cannot flow between the plunger 10 and the seal 19 or through the slot 28 and the at least one passage 29 within the seal 19.
• the seal 19 in this condition thus provides a seal between the plunger 10 and the wall of the bore 11, closing the check valve assembly, and allowing the plunger 10 to pump fluid from the secondary chamber 22 into the primary chamber 23.
• the present invention is a pump assembly with a combination reciprocating high-pressure seal and fluid inlet check valve for use within brake systems.
• the pump assembly comprises a piston for reciprocal movement within a bore in a housing.
• the pump assembly includes a housing having a bore formed therethrough and a piston disposed within the bore for reciprocal movement along a longitudinal axis therein.
• the piston has an inlet flange extending outwardly substantially perpendicular to the longitudinal axis.
• An annular seal is disposed around the piston for reciprocal movement thereon.
• the annular seal cooperates with at least one of the piston and the housing to form at least one longitudinally extending passageway.
• the piston has at least one passageway formed therein.
• the passageway, the piston, and the annular seal cooperate to form a check valve assembly.
• the retaining flange and the housing cooperate to form an outlet passageway of the check valve assembly.
• the annular seal is moveable to a first position relative to one of the inlet flange and the piston in which the at least one longitudinally extending passageway communicates directly with the outlet passageway to the pumping chamber and said check valve assembly is in e chamber during a fluid inlet stroke.
• the annular seal is moveable to a second position relative to the one of the inlet flange and the piston in which the check valve assembly is closed, for example, to pressurize the fluid within the pumping chamber during a pumping stroke.
• the piston includes a retaining flange, an inlet flange, and an intermediate portion disposed therebetween. Both the retaining flange and the inlet flange extend substantially perpendicular from the piston.
• the inlet flange and the housing cooperate to form at least one inlet passageway through the bore, and/or the intermediate portion of the piston has at least one longitudinally extending passageway formed therethrough.
• the retaining flange may also have at least one passageway formed therethrough.
• the at least one passageway of the intermediate portion and the at least one passageway of the retaining flange are communicably connected.
• the retaining flange and the housing cooperate to form at least one outlet passageway through the bore.
• the retaining flange may be comprised of a cir-clip disposed around the piston.
• the inlet flange may have at least one passageway formed therethrough.
• a high-pressure seal is disposed around the intermediate portion of the piston.
• the seal is not as thick as the intermediate portion is long, and, therefore, the seal can reciprocate between the retaining flange and inlet flange.
• the seal and the inlet flange cooperate to form a first check valve assembly, as will be described below.
• the piston, housing, the first check valve assembly, and a second check valve assembly define a pumping chamber.
• the piston, housing, and the first check valve assembly define an inlet chamber.
• a fluid inlet supplies fluid to the inlet chamber.
• the piston moves toward the second check valve assembly, and the seal is moved into a second position relative to the inlet fiange, in which the seal is seated against the inlet flange.
• the inlet flange and seal cooperate to prevent fluid from exiting the pumping chamber, such that the first check valve assembly is closed.
• the fluid pressure builds within the pumping chamber until the pressure overcomes the force required to unseat the ball of the second check valve assembly.
• the second check valve assembly then opens, allowing the pressurized fluid to exit the pumping chamber through a fluid outlet to be delivered to the vehicle brake system.
• the at least one passageway in the retaining flange is communicably connected to at least one passageway in the seal.
• the seal and the inlet flange form a check valve assembly.
• the check valve assembly When the seal is in the first position, fluid is allowed to flow through the at least one passageway in the inlet flange, below the seal, through the passageway in the seal, through the at least one passageway in the retaining flange, and into the pumping chamber.
• the check valve assembly is in a flow-through position.
• the seal is in a second position, seated against the sealing surface of the inlet flange, the at least one passageway in the seal is prevented from communicating with the at least one passageway in the inlet flange.
• the check valve assembly is in a closed position.
• FIG. 1 is a cross sectional view of a prior art hydraulic pump assembly.
• Fig. 2 is a cross sectional view of the seal of the prior art hydraulic pump assembly illustrated in Fig. 1.
• FIG. 3 is a perspective view of a first embodiment of a piston in accordance with the present invention.
• Fig. 4 is a cross sectional view of the piston shown in Fig. 3, taken along line 4-4, with the piston disposed within a first embodiment of a pump assembly, in accordance with the present invention.
• Fig. 5 is a cross sectional view of the pump assembly of Fig. 4.
• FIG. 6 is an enlarged cross sectional view of a portion of a second embodiment of a pump assembly in accordance with the present invention.
• FIG. 7 is a perspective view of a third embodiment of a piston in accordance with the present invention.
• Fig. 8 is a perspective view of a portion of the piston shown in Fig. 7 and a third embodiment of a seal in accordance with the present invention.
• Fig. 9 is a cross sectional view of the piston and seal shown in Figs. 7 and 8, taken along line 9-9, with the piston disposed within a third embodiment of a pump assembly, in accordance with the present invention.
• Fig. 10 is a cross sectional view of the pump assembly of Fig. 9.
• FIG. 11 is a perspective view of a fourth embodiment of a piston in accordance with the present invention.
• Fig. 12 is a top view of a portion of the piston shown in Fig. 11 and a fourth embodiment of a seal in accordance with the present invention. . 11 and 12, taken along line 13-13, with the piston disposed within a fourth embodiment of a pump assembly, in accordance with the present invention.
• Fig. 14 is a cross sectional view of the pump assembly of Fig. 13.
• a first embodiment of a piston indicated generally at 50, in accordance with this invention.
• the piston 50 comprises a shaft 51, a retaining flange 52, and an inlet flange 53.
• the retaining flange 52 extends substantially perpendicular from the shaft 51 at a first end portion 54 of the shaft 51.
• the inlet flange 53 extends substantially perpendicular from the shaft 51 below and spaced apart from the retaining flange 52.
• the retaining flange 52 and the inlet flange 53 cooperate to define an intermediate portion 55 of the shaft 51 disposed between retaining flange 52 and the inlet flange 53.
• the shaft 51 is generally elongated along a longitudinal axis A.
• the shaft 51 includes a second end portion 56, opposite the first end portion 54.
• the intermediate portion 55 described above is disposed between the first end portion 54 and the second end portion 56.
• the second end portion 56 is engaged by a driving mechanism (not shown) for reciprocatingly driving the piston 50.
• the intermediate portion 55 of the shaft 51 may have a generally circular cross section.
• the intermediate portion 55 extends outwardly from the axis A to a radius R ls as is shown in Figs. 4 and 5, and as will be described further below.
• the intermediate portion 55 has at least one passageway 57 formed therethrough.
• the at least one passageway 57 comprises a plurality of longitudinally extending grooves, with preferably semi-circular cross-section, that have been machined through the intermediate portion 55 of the shaft 51 around the periphery of the intermediate portion 55.
• the at least one passageway 57 comprises a plurality of longitudinally extending notches molded in the intermediate portion 55, with preferably rectangular or diamond-shaped cross-section.
• the at least one passageway 57 may be formed in the intermediate portion 55 in any manner, and may have any suitable cross-section.
• semi-circular encompasses any portion of a circle, which includes but is not limited to half of a circle.
• the at least one passageway 57 is formed through the intermediate portion 55 such that no part of the at least one passageway 57 extends further into the intermediate portion 55 than a radius R 2 from the axis A.
• the retaining flange 52 may have a generally circular cross section, and has a radius taken from the axis A that is larger than the radius R ! of the intermediate portion 55, the purpose of which will be described below.
• the retaining flange 52 has at least one passageway 58 formed therethrough.
• the at least one passageway 58 comprises a plurality of longitudinally extending grooves, preferably with semi-circular cross-section, that have been machined through the retaining flange 52 around the periphery of the retaining flange 52.
• the at least one passageway 58 comprises a plurality of longitudinally extending notches molded in the retaining flange 52, with preferably rectangular or diamond- shaped cross-section.
• the at least one passageway 58 may be formed in the retaining flange 52 in any manner, and may have any suitable cross-section. It will also be appreciated that the retaining flange 52 may be any one of a plurality of nubs or tangs extending outwardly from said piston 50, the purpose of which will be described below.
• the at least one passageway 58 is formed through the retaining flange 52 such that the at least one passageway 58 does not extend into the retaining flange 52 any closer than a radius R 3 from the axis A as seen in Fig. 4.
• the radius R 3 is smaller than the radius Rj of the intermediate portion, the such that the at least one passageway 58 is aligned to radially overlap the at least one passageway 57, and the at least one passageway 58 and the at least one passageway 57 are connected in fluid communication.
• the inlet flange 53 may have a circular cross section, and has at least one passageway 59 formed therethrough.
• the at least one passageway 59 comprises a plurality of longitudinally extending grooves, preferably with semi-circular cross-section, that have been machined through the inlet flange 53 around the periphery of the inlet flange 53.
• the at least one passageway 59 comprises a plurality of longitudinally extending notches molded in the inlet flange 53, with preferably rectangular or diamond-shaped cross-section.
• the at least one passageway 59 may be formed in the inlet flange 53 in any manner, and may have any suitable cross-section.
• the at least one passageway 59 is formed through the inlet flange 53 such that the at least one passageway 59 does not extend further into the inlet flange 53 any closer than a radius P from the axis A, as seen in Fig. 4.
• the radius ⁇ is greater th.an the radius R l5 the outer radius of the at least one passageway 57, such that even though the at least one passageway 57 and the passageway 59 may be aligned to overlap radially, the at least one passageway 57 and the at least one passageway 59 are not directly communicably connected with one another.
• the piston 50 is suitable for use in a pump assembly, such as the first embodiment of a pump assembly, indicated generally at 60, in Figs. 4 and 5.
• the pump assembly 60 comprises a housing 61 having a bore 62 formed therethrough.
• the piston 50 is mounted for reciprocal movement within the bore 62 of the housing 61.
• the piston 50 is formed of a material that is sufficient to sustain operation of the pump assembly 60 under operating conditions within the pump assembly 60 as described herein, such as the relatively high operating pressures of a pump assembly within a vehicle brake system.
• the piston 50 is comprised of materials that are compatible with hydraulic brake fluid.
• An .annuls high-pressure seal 63 is disposed around the intermediate portion 55 of the piston 50.
• the high-pressure seal 63 has a generally rectangular radial cross section as illustrated for each portion of the seal 63 shown on either side of the axis A in Fig. 4.
• the seal may have any radial cross-section.
• the seal 63 is not as thick as the intermediate portion 55 is long, such that the seal 63 can reciprocate between the retaining flange 52 and the inlet flange 53 of the piston 50, as will be described below.
• the seal 63 is preferably elastomeric.
• the seal 63 includes a base material, such as Polytetrafluoroethylene (PTFE) sold under the tradename Teflon® .and manufactured by DuPont, and a filler material, such as carbon.
• PTFE Polytetrafluoroethylene
• the seal 63 includes carbon fiber, or other high tensile strength fibers suitable for use in composite materials.
• the seal 63 is formed of a material that is sufficient to sustain operation of the pump assembly 60 under operating conditions within the pump assembly 60 as described herein, such as the relatively high operating pressures of a pump assembly within a vehicle brake system.
• the seal 63 is formed of a material that is sufficient to sustain operation of the pump assembly 60 with .an operating pressure range of about 0 to about 250 bars absolute pressure within the pump assembly 60, as will be described in more detail below. However, it will be appreciated that operating pressure within the pump assembly 60 may vary, and may be a negative pressure under some operating conditions, as will be described below.
• the seal 63 is formed of a material that is sufficient to sustain operation of the pump assembly 60 in a temperature range of about -40 degrees Celsius to about 120 degrees Celsius. Additionally, in a preferred embodiment, the seal 63 is comprised of materials that are compatible with hydraulic brake fluid.
• the seal 63 has a first surface 64 that slidingly engages the walls of the housing 61 that form the bore 62 to form a dynamic seal therebetween.
• the seal 63 also has a second surface 65 that slidingly engages the outer periphery of the intermediate portion 55 of the piston 50, although such is not required.
• the seal 63 is able to move relative to the intermediate portion 55 between a first position, in which the seal 63 contacts the retaining flange 52 and a second position, in which the seal 63 contacts the inlet flange 53 as will be described below.
• the second surface 65 may seal against only the outer periphery of the intermediate portion 55, and does not contact the inner periphery of the at least one passageway 57, such that the seal 63 does not enter the at least one passageway 57. Thus, no seal is formed between the seal 63 and the intermediate portion 55.
• the seal 63 further includes a third surface 66 that engages a surface
• the at least one passageway 58 is a plurality of similar passageways in the form of grooves that are symmetrically positioned around the retaining flange 52, so that the seal 63 is evenly axially supported by the retaining flange 52 when seated in the first position.
• the seal 63 has a fourth surface 67 that may engage a sealing surface
• the seal 63 prevents fluid flow through the at least one passageway 59 through the inlet flange 53, because, as is best shown in Fig. 5, the seal 63 seats against the sealing surface 69 blocking the passageway 59. Fluid is not able to flow out of the at least one passageway 57 past the seal 63, so fluid is not able to flow from the at least one passageway 57, around the seal 63, and into the at least one passageway 59. Therefore, the seal 63, in the second position, prevents the at least one passageway 57 and the at least one passageway 59 from fluid communication with one another.
• the seal 63 and the inlet flange 53 cooperate to form a first check valve assembly 70, as will be described in more detail below.
• the at least one passageway 59 is a plurality of similar passageways that are symmetrically positioned around the inlet flange 53, so that the seal 63 is evenly supported by the inlet flange 53 when seated in the second position.
• the seal 63 is a non-metallic seal that has featureless first and second end faces, i.e. the third and fourth surfaces 66 and 67.
• a longitudinal central bore is defined by the inner wall, i.e. the second surface 65, extending between the first and second end faces, i.e.
• a groove is formed in the inner wall, i.e. the second surface 65, and extends from the first end face to the second end face, i.e. from the third surface 66 to the second surface 67.
• the pump assembly 60 will now be further described.
• the second end portion 56 of the piston 50 is mounted so that the piston 50 may reciprocate within the bore 62 of the housing 61.
• the piston 50 slides against the walls of the bore 62 as the piston 50 reciprocates.
• a seal 71 may be provided or formed by the piston 50 and the walls of the bore 62.
• the seal 71, the seal 63, and the piston 50 define an inlet chamber 72 within the bore 62.
• a fluid inlet 73 is communicably connected to the inlet chamber 72 to supply fluid to the pump assembly 60, as will be described below.
• the seal 71 may not be provided, and the inlet chamber 72 may extend such that the fluid of the inlet chamber 72 may be used to lubricate the piston 50 .and the walls of the bore 62 to facilitate the reciprocal movement therebetween.
• an o-ring (not shown) may be disposed around the shaft 51 of the piston 50 near the second end portion 56 of the piston 50 instead of the seal 71 such that the inlet chamber 72 extends below the intersection of the walls of the bore 62 and the piston 50.
• a second check valve assembly 74 is provided at the end of the bore 62 opposite the piston 50.
• the second check valve assembly 74 includes a ball 75 and a seat 76.
• the second check valve assembly 74 is formed of a material that is sufficient to sustain operation of the pump assembly 60 under operating conditions within the pump assembly 60 as described herein, such as the relatively high operating pressures of a pump assembly within a vehicle brake system.
• second check valve assembly 74 is comprised of materials that are compatible with hydraulic brake fluid.
• a pumping chamber 77 is defined within the bore 62 between the second check valve assembly 74 and the combination of the piston 50 and the seal 63.
• the differential pressure unseats the seal 63 from the inlet flange 53, opening the first check valve assembly 70 and allowing fluid to flow from the inlet chamber 72 through the passageways 59, 57, and 58, into the pumping chamber 77.
• the seal 63 will generally have greater friction to the wall of the bore 62 than to the piston 50, and will tend to remain stationary as the piston 50 moves.
• the retaining flange 52 will eventually intercept the seal 63, and the seal 63 will be drug away from the second check valve assembly 74 by the retaining flange 52 of the piston 50, so that the seal 63 is now in the first position thereof.
• the seal 63 will remain seated against the retaining flange 52 as long as the piston 50 continues to move in the same direction, e.g., away from the second check valve assembly 74.
• the piston 50 moves back toward the second check valve assembly 74.
• the seal 63 again tends to remain stationary due to friction with the wall of the bore.
• pressure starts to rise, even with the first check valve assembly 70 still open, due to head losses in the passageways.
• the seal 63 moves out of the second position thereof.
• the pump assembly 60 may be a self-priming or pre-charging pump, and the pump assembly 60 may operate with negative pressure conditions within the inlet chamber 72.
• the first end portion 54 of the piston 50 is relatively close to the second check valve assembly 74.
• the first check valve assembly 70 and the second check valve assembly 74 are in relatively close proximity to one another, such that the pumping chamber 77 is relatively small, as compared to the pumping chambers of conventional pumps.
• the axial distance between the first check valve assembly 70 and the second check valve assembly 74 is minimized so that the pump assembly 60 has a relatively small unswept volume.
• the size and design of the seal 63, the at least one passageway 58 of the retaining flange 52, and the at least one passageway 59 of the inlet flange 53 must be coordinated so that the seal 63 and piston 50 cooperate such that the pump 60 operates as described above.
• the seal 63, the at least one passageway 58 of the retaining flange 52, and the at least one passageway 59 of the inlet flange 53 could be any size or shape capable of performing as described above.
• FIG. 6 there is illustrated a portion of a second embodiment of a pump assembly, indicated generally at 160, in accordance with this invention.
• the pump assembly 160 is similar to the pump assembly 60, and only those elements that differ will be described herein, and corresponding elements have been given the same reference numeral incremented by 100.
• the piston 150 includes a retaining flange 152, an inlet flange 153, and an intermediate portion 155 disposed therebetween. Unlike the intermediate portion 55 of the piston 50, the intermediate portion 155 of the piston 150 does not have a passageway formed therethrough. Instead, the intermediate portion 155 is preferably circular in cross-section, and is slidingly engaged by a seal 163. The seal 163 may reciprocate between the retaining flange 152 and the inlet flange 153, in a manner similar to that described above for the seal 63.
• the seal 163 differs from the seal 63 in that the seal 163 has at least one passageway 180 formed therethrough.
• the at least one passageway 180 has an outer radius R] from the axis A.
• the outer radius Rl is smaller than the inner radius R of the at least one passageway 159 in the inlet flange 153.
• the outer radius R is larger than the inner radius R 3 of the at least one passageway 158 in the retaining flange 152.
• the seal 163 and the inlet flange 153 form a check valve assembly 170.
• the at least one passageway 158 in the retaining flange 152 is communicably connected to the at least one passageway 180 in the seal 163.
• the at least one passageway 180 is a plurality of passageways sized such that no matter how the seal 163 is rotated relative to the retaining flange 152, the at least one passageway 180 is communicably connected to the at least one passageway 158 of the retaining flange 152, when the seal 163 is seated against the surface 168.
• the seal 163 When the seal 163 is in a first position relative to the inlet flange 153, the seal 163 is unseated from the sealing surface 169 of the inlet flange 153, and may be seated against the surface 168 of the retaining flange 152, as described in the previous embodiment and as shown in Fig. 6.
• the seal 163 When the seal 163 is in the first position, fluid is allowed to flow through the at least one passageway 159, below the seal 163, through the passageway 180, through the at least one passageway 158, and into the pumping chamber 177.
• the check valve assembly 170 is in a flow-through position.
• the check valve assembly 170 is in a closed position, such that the pump 160 works in a manner similar to that described for the pump 60.
• a third embodiment of a piston indicated generally at 250, in accordance with this invention.
• the piston 250 comprises a shaft 251, a retaining flange 252, and an inlet flange 253.
• the retaining flange 252 extends substantially perpendicular from the shaft 251 near a first end portion 254 of the shaft 251.
• the inlet flange 253 extends substantially perpendicular from the shaft 251 below and spaced apart from the retaining flange 252.
• the retaining flange 252 and the inlet flange 253 cooperate to define an intermediate portion 255 of the shaft 251 disposed between retaining flange 252 and the inlet flange 253.
• the retaining flange 252 may have a generally circular cross section, and has a radius taken from the axis A that is larger than a radius Ri taken from the axis A of the intermediate portion 255, the purpose of which will be described below.
• the inlet flange 253 may have a generally circular cross section, and has a radius taken from the axis A that is larger that the radius Ri of the intermediate portion 255.
• the shaft 251 is generally elongated along longitudinal axis A.
• the shaft 251 includes a second end portion 256, opposite the first end portion 254.
• the intermediate portion 255 described above is disposed between the first end portion 254 and the second end portion 256.
• the second end portion 256 is engaged by a driving mechanism (not shown) for reciprocatingly driving the piston 250.
• the intermediate portion 255 of the shaft 251 may have a generally circular cross section.
• the intermediate portion 255 extends outwardly from the axis A to the radius Rj, as is shown in Figs. 9 and 10, and as will be described further below.
• an annular high-pressure seal 257 is disposed around the intermediate portion 257 of the piston 250.
• the high-pressure seal 257 has a generally rectangular radial cross section as illustrated for each portion of the seal 257 shown on either side of the axis A in Fig. 8.
• the seal may have any radial cross-section.
• the seal 257 is not as thick as the intermediate portion 255 is long, such that the seal 257 can reciprocate between the retaining flange 252 and the inlet flange 253 of the piston 250, as will be described below.
• the seal 257 is preferably elastomeric.
• the seal 257 may preferably include a low friction plastic, such as nylon.
• the seal 257 includes a base material, such as Polytetrafluoroethylene (PTFE) sold under the tradename Teflon® and manufactured by DuPont, and a filler material, such as carbon.
• PTFE Polytetrafluoroethylene
• the seal 257 includes carbon fiber, or other high tensile strength fibers suitable for use in composite materials.
• the seal 257 has at least one passageway 258 formed therethrough.
• the at least one passageway 258 comprises a plurality of longitudinally extending grooves, preferably with semi-circular cross-section, that have been formed in or machined through the seal 257 around an inner periphery of the seal 257.
• the at least one passageway 258 comprises a plurality of longitudinally extending notches molded in the seal 257, with preferably rectangular or diamond-shaped cross-section.
• the at least one passageway 258 may be formed in the seal 257 in any manner, and may have any suitable cross-section.
• the at least one passageway 258 is formed through the seal 257 such that the at least one passageway 258 does not extend outw.ardly into the seal 257 any further than a radius R 2 from the axis A as shown in Fig. 9.
• the piston 250 is suitable for use in a pump assembly, such as the third embodiment of a pump assembly, indicated generally at 259, in Figs. 9 and 10.
• the pump assembly 259 comprises a housing 260 having a bore 261 formed therethrough.
• the piston 250 is mounted for reciprocal movement within the bore 261 of the housing 260.
• the piston 250 is comprised of materials that are compatible with hydraulic brake fluid.
• the seal 257 is formed of a material that is sufficient to sustain operation of the pump assembly 259 under operating conditions within the pump assembly 259 as described herein, such as the relatively high operating pressures of a pump assembly within a vehicle brake system.
• the seal 257 is formed of a material that is sufficient to sustain operation of the pump assembly 259 with an operating pressure range of about 0 to about 50 bars absolute pressure within the pump assembly 259, as will be described in more detail below. However, it will be appreciated that operating pressure within the pump assembly 259 may vary, and may be a negative pressure under some operating conditions, as will be described below.
• the seal 257 is formed of a material that is sufficient to sustain operation of the pump assembly 259 in a temperature range of about -40 degrees Celsius to about 120 degrees Celsius. Additionally, in a preferred embodiment, the seal 257 is comprised of materials that are compatible with hydraulic brake fluid.
• the retaining flange 252 and the housing 260 cooperate to form an outlet passageway 262 through the bore 261.
• the outlet passageway 262 is generally annular and extends about the periphery of the retaining flange 252, although such is not required.
• the outlet passageway 262 may have any desired shape and may be disposed about or through any portion of the retaining flange 252.
• the outlet passageway 262 has an inner radius R taken from the axis A.
• the outlet passageway 262 is formed between retaining flange 252 and the housing 260 such that the outlet passageway 262 does not extend further into the retaining flange 252 any closer than the radius R 3 from the axis A, as seen in Fig. 8.
• the inner radius R 3 may be smaller than the outer radius R 2 of the seal 257 and may be larger than the outer radius R] of the intermediate portion 255.
• the inlet flange 253 and the housing 260 cooperate to form an inlet passageway 263 through the bore 261.
• the inlet passageway 263 is generally annular and extends about the periphery of the inlet flange 253, although such is not required.
• the inlet passageway 263 may have any desired shape and may be disposed about or through any portion of the inlet flange 253.
• the inlet passageway 263 has an inner radius R 4 taken from the axis A.
• the inlet passageway 263 is formed between inlet flange 253 and the housing 260 such that the inlet passageway 263 does not extend further into the inlet flange 253 any closer th.an the radius R 4 from the axis A, as seen in Fig. 8.
• the radius j is greater than the radius R 2 , the outer radius of the at least one passageway 258, such that even though the at least one passageway 258 and the passageway 263 may be aligned to overlap radially, the at least one passageway 258 and the passageway 263 are not directly communicably connected with one another.
• the seal 257 has a first surface 264 that slidingly engages the walls of the housing 260 that form the bore 261 to form a dynamic seal therebetween.
• the seal 257 also has a second surface 265 that slidingly engages the outer periphery of the intermediate portion 255 of the piston 250, although such is not required.
• the seal 257 is able to move relative to the intermediate portion 255 between a first position, in which the seal 257 contacts the retaining flange 252 and a second position, in which the seal 257 contacts the inlet flange 253 as will be described below.
• the seal 257 further includes a third surface 266 that engages a surface 268 of the retaining flange 252 when the seal 257 is in the first position thereof.
• the at least one passageway 258 is a plurality of similar passageways in the form of grooves that are symmetrically positioned around the seal 257, so that the seal 257 is evenly axially supported by the retaining flange 252 when seated in the first position.
• the seal 257 has a fourth surface 267 that may engage a sealing surface 269 of the inlet flange 253 when the seal 257 is in a second position relative to the inlet flange 253, as will be described below.
• the fourth surface 267 engages the sealing surface 269.
• the seal 257 prevents fluid flow through the at least one passageway 259 through the inlet flange 253, because, as is best shown in Fig. 9, the seal 257 seats against the sealing surface 269 blocking the passageway 263. Fluid is not able to flow out of the at least one passageway 258 past the seal 257, so fluid is not able to flow from the at least one passageway 258, around the seal 257, and into the passageway 263. Therefore, the seal 257, in the second position, prevents the at least one passageway 258 and the passageway 263 from fluid communication with one another.
• the seal 257 and the inlet flange 253 cooperate to form a first check valve assembly 270, as will be described in more detail below.
• the at least one passageway 258 is a plurality of similar passageways that are symmetrically positioned throughout the seal 257, so that the seal 257 is evenly supported by the inlet flange 253 when seated in the second position.
• the pump assembly 259 will now be further described.
• the second end portion 256 of the piston 250 is mounted so that the piston 250 may reciprocate within the bore 261 of the housing 260.
• the piston 250 slides against the walls of the bore 261 as the piston 250 reciprocates.
• a seal 271 may be provided or formed by the piston 250 and the walls of the bore 261.
• the seal 271, the seal 257, and the piston 250 define an inlet chamber 272 within the bore 261.
• a fluid inlet 273 is communicably connected to the inlet chamber 272 to supply fluid to the pump assembly 259, as will be described below.
• the seal 271 may not be provided, and the inlet chamber 272 may extend such that the fluid of the inlet chamber 272 may be used to lubricate the piston 250 and the walls of the bore 261 to facilitate the reciprocal movement therebetween.
• an o-ring (not shown) may be disposed around the shaft 251 of the piston 250 near the second end portion 256 of the piston 250 instead of the seal 271 such that the inlet chamber 272 extends below the intersection of the walls of the bore 261 and the piston 250.
• a second check valve assembly 274 is provided at the end of the bore 261 opposite the piston 250.
• the second check valve assembly 274 includes a ball 275 and a seat 276.
• the second check valve assembly 274 is formed of a material that is sufficient to sustain operation of the pump assembly 259 under operating conditions within the pump assembly 259 as described herein, such as the relatively high operating pressures of a pump assembly within a vehicle brake system. Additionally, in a preferred embodiment, second check valve assembly 274 is comprised of materials that are compatible with hydraulic brake fluid.
• a pumping chamber 277 is defined within the bore 261 between the second check valve assembly 274 and the combination of the piston 250 and the seal 257. As is evident from the structure of the pump 259 and as will be evident from the operation of the pump 259 described below, the pump 259 is highly efficient due to the relatively small unswept volume of the piston 250.
• the differential pressure unseats the seal 257 from the inlet flange 253, opening the first check valve assembly 270 and allowing fluid to flow from the inlet chamber 272 through the passageways 263, 258, and 262, into the pumping chamber 277.
• the seal 257 will generally have greater friction to the wall of the bore 261 than to the piston 250, and will tend to remain stationary as the piston 250 moves.
• the retaining flange 252 will eventually intercept the seal 257, and the seal 257 will be urged away from the second check valve assembly 274 by the retaining flange 252 of the piston 250, so that the seal 257 is now in the first position thereof.
• the seal 257 will remain seated against the retaining flange 252 as long as the piston 250 continues to move in the same direction, e.g., away from the second check valve assembly 274.
• the seal 257 will remain in the second position thereof, i.e. seated against the inlet flange 253, as long as the piston 250 continues to move in the same direction, e.g., toward the second check valve assembly 274.
• the first check valve assembly 270 is in the closed position, as illustrated in Fig. 10.
• the fluid pressure within the chamber 277 continues to build until the fluid pressure within the chamber 277 is greater than the resistance required to unseat the ball 275 from the seat 276 of the second check valve assembly 274.
• the second check valve assembly 274 opens and pressurized fluid is discharged from the pump 259 via an outlet 278.
• the pump assembly 259 may be a self-priming or pre-charging pump, and the pump assembly 259 may operate with negative pressure conditions within the inlet chamber 272.
• the first end portion 254 of the piston 250 is relatively close to the second check valve assembly 274.
• the first check valve assembly 270 and the second check valve assembly 274 are in relatively close proximity to one another, such that the pumping chamber 277 is relatively small, as compared to the pumping chambers of conventional pumps.
• the axial distance between the first check valve assembly 270 and the second check valve assembly 274 is minimized so that the pump assembly 259 has a relatively small unswept volume.
• seal 257, the at least one passageway 258, the passageway 262, and the passageway 263, must be coordinated so that the seal 257 and piston 250 cooperate such that the pump 259 operates as described above.
• seal 257, the at least one passageway 258, the passageway 262, and the passageway 263 could be any size or shape capable of performing as described above.
• FIG. 11 through 14 there is illustrated a portion of a fourth embodiment of a pump assembly, indicated generally at 359, in accordance with this invention.
• the pump assembly 359 is similar to the pump assembly 259, and only those elements that differ will be described herein, and corresponding elements have been given the same reference numeral incremented by 100.
• the retaining flange 252 is integral to the piston 250.
• the retaining flange 252 and the piston 250 may be formed as an integral unit, or the retaining flange 252 may be formed separately and permanently fixed to the piston 250 by any suitable means, such as welding or permanent adhesive, etc.
• the retaining flange may be formed separately and non-permanently affixed to the piston 250.
• the retaining flange may be pressed on, affixed with a snap fit, affixed with threading or any other non-permanent method. Such an arrangement may be advantageous in facilitating the positioning of an original or replacement seal onto the piston.
• the piston 350 includes a cir-clip 352 disposed around the piston 350 to form a retaining flange, similar in function to the retaining flange 252.
• the piston 350 further includes an inlet flange 353 and an intermediate portion 355 disposed between the cir-clip 352 .and the inlet flange 353.
• the cir-clip 352 of the piston 350 does not have an annular passageway, like passageway 262, formed about the outer annular periphery of the cir-clip 352.
• the cir-clip 352 is preferably semicircular in cross-section, and may have a passageway 362 formed about the portion of the piston 350 in which the cir-clip 352 does not extend.
• the cir-clip 352 does not extend about a portion of the piston 350 that is about 110° of the circumference of the piston 350.
• the passageway 362 formed by the piston 350, the cir-clip 352, and the housing 360 may extend between a portion of the cir-clip 352 and the piston 350 and/or between a portion of the cir-clip 352 and the housing 360, as shown in Fig. 12.
• the seal 357 may reciprocate between the cir-clip 352 and the inlet flange 353, in a manner similar to that described above for the seal [0076]
• the seal 357 differs from the seal 257 in that the seal 357 does not have a passageway formed therethrough.
• the seal 357, the piston 350, and the housing 360 cooperate the form at least one passageway 358 between the seal 357 and the piston 350 about an inner periphery of the seal 357.
• the at least one passageway 358 formed between the seal 357 and the piston 350 is generally annular, although such is not required.
• the seal 357 may include various passageways formed therein, such as the at least one passageway 258 described in the prior embodiment.
• the at least one passageway 358 has an outer radius R 2 from the axis A.
• the outer radius R 2 is smaller than an inner radius R 4 of a passageway 363 formed by the inlet flange 353 and the housing 360.
• the at least one passageway 358 has an inner radius Rj from the axis A.
• the inner radius ⁇ is larger than the inner radius R 3 of the passageway 362 formed by the retaining flange 352 and the housing 360.
• the inner radius Ri may also be larger than an outer radius of the passageway 362, although such is not required. If the inner radius Ri is larger than an outer radius of the passageway 362, as shown in Figs. 13 and 14, the piston 350 may be shaped such that the at least one passageway 358 and the passageway 362 are communicable connected.
• piston 350, the at least one passageway 358, the passageway 362, and the housing 360 may be shaped in any manner relative to one another, such that the piston 350, the at least one passageway 358, the passageway 362, and the housing 360 cooperate so that the at least one passageway 358 and the passageway 362 are communicable connected.
• the seal 357 and the inlet flange 353 form a check valve assembly 370.
• the structure of the check valve assembly 370 varies from structure of the check valve assembly 270.
• the at least one passageway 358 is communicably connected to the passageway 362 formed by the cir-clip 352, the piston 350, and the housing 360.
• the at least one passageway 358 is shaped such that no matter how the seal 357 is rotated relative to the cir-clip 352, the at least one passageway 358 is communicably connected to the passageway 362.
• the seal 357 When the seal 357 is in a first position relative to the inlet flange 353, the seal 357 is unseated from the sealing surface 369 of the inlet flange 353, and may be seated against the surface 368 of the cir-clip 352, as described in the previous embodiment and as shown in Fig. 13.
• the seal 357 When the seal 357 is in the first position, fluid from the fluid inlet 373 is allowed to flow from the inlet chamber 372 through the passageway 363, below the seal 357, through the at least one passageway 358, through the passageway 363, and into a pumping chamber 377.
• the check valve assembly 370 is in a flow-through position.
• the check valve assembly 370 is in a closed position, such that the pump 359 works in a manner similar to that described for the pump 259.
• the pistons 50, 150, 250, 350 seals 57, 157, 257, 357 and pump assemblies, 59, 159, 259, 359 have been described for use in a vehicle braking system, including, but not limited to, vehicle braking systems having anti-lock braking systems, and/or integrated or stand alone traction control and vehicle stability control systems.
• vehicle braking systems having anti-lock braking systems, and/or integrated or stand alone traction control and vehicle stability control systems.
• the pistons 50, 150, 250, 350 the seals 57, 157, 257, 357 and pump assemblies 59, 159, 259, 359 may be used in any vehicle component or in any other device requiring a piston, seal, or pump assembly.

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• Engineering & Computer Science (AREA)
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• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
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• Details Of Reciprocating Pumps (AREA)

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• 2004
  • 2004-10-01 EP EP04794085A patent/EP1667880A1/de not_active Withdrawn
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