104 and the MPA cavity 110 by traveling between the MPA fill valve poppet 132 and the MPA lip seal 136.

At least a first length of the MPA fill valve poppet 132 is located within the MPA cavity 110 when the MPA cavity 110 includes the predetermined fill amount of hydraulic fluid. This is the configuration shown in FIG. 4. In the sequence of views running from FIG. 4 through to FIG. 5, then, the MPA fill valve poppet 132 selectively reciprocates within the MPA fill valve cavity 110 responsive to at least one of biasing force from the MPA valve biasing spring 142 and a fluid pressure differential between the source of pressurized hydraulic fluid and the MPA cavity 110. (E.g., the fluid pressure within the MPA cavity 110 works to overcome the biasing force from the MPA valve biasing spring 142, move the MPA poppet shoulder 140 away from the MPA fill valve seat 128, and thus obtain more pressurized fluid from the pressurized fluid source.)

A second length of the MPA fill valve poppet 132 (represented schematically as being smaller than the first length of the MPA fill valve poppet 132) protrudes into, and remains located within, the MPA cavity 110, as shown in FIGS. 5-6, when the MPA cavity 110 includes substantially the predetermined fill amount of hydraulic fluid and/or there is a predetermined pressure differential between the MPA cavity 110 and the source of hydraulic fluid. Because the second length of the MPA fill valve poppet 132 represents an amount that allows the MPA fill valve poppet 132 to be in the “rest” position”, any desired amount of pressurized hydraulic fluid is permitted to flow along the MPA fill valve fluid path FVP and/or between the MPA fill valve poppet 132 and the lip seal 136. and routed through the brake system in a predetermined manner; one of ordinary skill in the art can readily provide a suitably configured accumulator assembly 100 and/or brake system to achieve a desired braking performance for a particular use environment.

Alternative configurations (not shown) which may be suitable for particular use environments include, but are not limited to, attaching the MPA fill valve poppet 132 directly or indirectly to the MPA piston 118 for reciprocal travel therewith; configuring the MPA biasing spring 124 to hold the MPA fill valve poppet 132 into reciprocating contact with the MPA piston 118 for reciprocal travel therewith; providing a blocking component and/or mechanism to permanently prevent the “bleed valve” fluid flow backward up the MPA fill valve fluid path FVP after the initial non-powered evac/fill process; and/or intentionally leaving a small amount of air in the MPA cavity 110 after the initial non-powered evac/fill process and subsequently operating one or more other components of the brake system, optionally in a cyclical manner, to provide a self-bleed function that sends the small “remainder” amount of air from the MPA cavity 110 out of the brake system.

FIGS. 7-9 schematically depict the structures and operation of a powered MPA one-way valve 106 which is interposed fluidically between the brake-side passage 112 of the MPA cavity 110 and at least one corresponding wheel brake. The MPA one-way valve 106 includes an MPA one-way valve cavity 146 placing the brake-side passage 112 of the MPA cavity 110 and the at least one corresponding wheel brake in selective fluid communication via an MPA one-way valve fluid path OVP (shown schematically in FIG. 9). An MPA one-way valve seat 148 is located along the MPA one-way valve fluid path OVP and is defined by an interior wall 150 of the MPA one-way valve cavity 146.

An MPA one-way valve poppet 152 is configured for reciprocal motion between a poppet open position and a poppet closed position. When the MPA one-way valve poppet 152 is in the poppet closed position, an MPA one-way valve poppet shoulder 154 contacts the MPA one-way valve seat 148 to occlude fluid flow therepast along the MPA one-way valve fluid path OVP. Reciprocal motion of the MPA one-way valve poppet 152 occurs at least partially responsive to a predetermined amount of fluid pressure differential between the MPA cavity 110 and the at least one corresponding wheel brake, as will be described below.

The MPA one-way valve 106 includes an armature 156 for selective longitudinally reciprocating motion with respect to the MPA one-way valve cavity 146 between first and second armature positions (shown in FIGS. 7, and 8-9, respectively). The “longitudinal” direction, as referenced herein with respect to the MPA one-way valve, is substantially parallel to arrow “L”, and is depicted as a vertical direction, in the orientation of FIG. 7. The MPA one-way valve 106 includes a core 158 for selectively magnetically attracting the armature 156. The core 158 is located longitudinally directly adjacent a core-activated surface 160 of the armature 156. The armature 156 is longitudinally interposed between the core 158 and the MPA one-way valve poppet 152. The core 158 is selectively energized to magnetically drive the armature 156 between the first armature position of FIG. 7 and the second armature position of FIGS. 8-9. A core spring 162 biases the armature 156 toward the MPA one-way valve poppet 152—i.e., toward the first armature position—to make the MPA one-way valve 106 a normally-closed type of valve, which is then electrically (solenoid) actuated to selectively open.

The MPA one-way valve poppet 152 is held into engagement with the MPA one-way valve seat 148, in the poppet closed position, responsive to the armature 156 being in the first armature position. As a result, the MPA one-way valve fluid path OVP is occluded when the armature 156 is in the first armature position, and pressurized hydraulic fluid is not permitted to travel from the medium pressure accumulator 102 toward the wheel brake. The MPA one-way valve poppet 152 is permitted to selectively reciprocate between the poppet closed position of FIG. 8 and the poppet open position of FIG. 9 responsive to the armature 156 being in the second armature position. As a result, the MPA one-way valve fluid path OVP may be occluded when the armature 156 is in the second armature position, or may not be occluded at that time, depending upon the position of the MPA one-way valve poppet 152.

A poppet spring 164 biases the MPA one-way valve poppet 152 toward the poppet closed position and thus biases the MPA one-way valve poppet shoulder 140 toward sealing engagement with the MPA one-way valve seat 148 when the armature 156 is in the second armature position. Again, this is the arrangement shown in FIG. 8. Conversely, reciprocal motion of the MPA one-way valve poppet 152 from the poppet closed position of FIG. 8 toward the poppet open position of FIG. 9 is permitted to occur at least partially responsive to a fluid pressure in the MPA cavity 110 (i.e., in the brake-side passage 112) being greater than a predetermined wheel-side fluid pressure (i.e., in the wheel-side passage represented by 166), which is related to fluid pressure at the at least one corresponding wheel brake, optionally adjusted to account for pressure drop occurring in an intervening length of hydraulic line travel. When the MPA one-way valve poppet 152 is urged toward the poppet open position of FIG. 9 by fluid pressure from the brake-side passage 112, the MPA one-way valve fluid path OVP is permitted to open, and pressurized hydraulic fluid flows through the MPA one-way valve 106, along the MPA one-way valve fluid path OVP, toward the brake to facilitate a “spike apply”, or otherwise to provide pressurized hydraulic fluid to the wheel brake in a desired manner for operation of the brake system.

The MPA one-way valve 106 may be configured and constructed in any desired manner, and may readily be provided by one of ordinary skill in the art for a desired use environment. By way of example, given the medium pressures previously mentioned, the MPA one-way valve fluid path OVP might be configured to take about 10 bars of force from the brake-side passage 112 direction (to overcome spring force of at least one of the core and poppet springs 162 and 164) to open when the MPA one-way valve 106 is in the FIG. 7 configuration, about 80 mbars (to overcome the force of the poppet spring 164 and shift the MPA one-way valve poppet 152 initially) to start opening in the FIG. 8 configuration, and about 180 mbars (to move the MPA one-way valve poppet 152 fully away from the MPA one-way valve seat 148) to fully open into the FIG. 9 configuration.

The example MPA one-way valve 106 configuration shown in the Figures includes a core sleeve 168 received at least partially in a housing 108 that also at least partially defining the MPA cavity 110. The core sleeve 168, when present, is configured to maintain the core 158 in spaced relationship with the armature 156. The armature 156 is at least partially enclosed within the core sleeve 168 is and guided thereby for selective longitudinal reciprocating motion with respect to the core 158, responsive to energization of the core 158. Optionally, and also as shown in the Figures, the core sleeve 168 may completely enclose the MPA one-way valve poppet 152.

The core sleeve 168 is shown as having a reduced-diameter sleeve shoulder 170, located on an opposite end of the MPA one-way valve poppet 152 from the core 158. The sleeve shoulder 170 at least partially defines the MPA one-way valve seat 148 by comprising at least a portion of an interior wall 150 of the MPA one-way valve cavity 146, at that location on the MPA one-way valve 106. Any desired number, configuration, and type of resilient seals 172, to prevent fluid leakage; retainers 174, to keep the components of the MPA one-way valve 106 spaced or arranged as desired; and/or flanges 176, to maintain the MPA one-way valve 106 within the block housing 108, may be provided by one of ordinary skill in the art for a particular use environment of the accumulator assembly 100.

FIG. 10 schematically depicts an example brake system 178 for actuating a plurality of wheel brakes 180 comprising first and second pairs of wheel brakes 180. The brake system 178 is shown here as a hydraulic braking system, in which fluid pressure is utilized to apply braking forces for the brake system 178. The brake system 178 may suitably be used on a ground vehicle, such as an automotive vehicle having four wheels with a wheel brake associated with each wheel. Furthermore, the brake system 178 can be provided with other braking functions such as anti-lock braking (ABS) and other slip control features to effectively brake the vehicle. Components of the brake system 178 may be housed in one or more blocks or housings. The blocks or housings may be made from solid material, such as aluminum, that has been drilled, machined, or otherwise formed to house the various components. Fluid conduits may also be formed in the block or housing.

In the illustrated embodiment of the brake system 178 of FIG. 10, there are four wheel brakes 180, which each can have any suitable wheel brake structure operated electrically and/or by the application of pressurized brake fluid. Each of the wheel brakes 180 may include, for example, a brake caliper mounted on the vehicle to engage a frictional element (such as a brake disc) that rotates with a vehicle wheel to effect braking of the associated vehicle wheel. The wheel brakes 180 can be associated with any combination of front and rear wheels of the vehicle in which the corresponding brake system 178 is installed. For example, the brake system 178 may be configured as a vertically split or diagonally split system. No differentiation is made herein among the construction of the various wheel brakes 180, for the purposes of this description, though one of ordinary skill in the art could readily provide a suitable braking arrangement for a particular use environment. The wheel brakes 180 are described herein as comprising first and second pairs of wheel brakes 180, with the first and second pairs being characterized as RF/LR and LF/RR, as shown as FIG. 10, for the sake of description. However, LF/LR and RF/RR, or RF/LF and RR/LR, pairs could also or instead be specified for the brake system 178, as desired.

Also for the sake of description, it is presumed that a deceleration signal transmitter (shown schematically at 184) is configured to provide a braking signal, in a wired or wireless manner, corresponding to a desired braking action by an operator of the vehicle. The deceleration signal transmitter 184 could include, but not be limited to, a brake pedal, an autonomous braking controller, and/or any other suitable scheme for generating a braking signal from which the brake system 178 can be actuated.

The brake system 178 also includes a fluid reservoir 186. The reservoir 186 stores and holds hydraulic fluid for the brake system 178. The fluid within the reservoir 186 is preferably held at or about atmospheric pressure, but the fluid may be stored at other pressures if desired. The reservoir 186 is shown schematically as having three tanks or sections in FIG. 10, with fluid conduit lines connected thereto. The sections can be separated by several interior walls within the reservoir 186 and are provided to prevent complete drainage of the reservoir 186 in case one of the sections is depleted due to a leakage via one of the three lines connected to the reservoir 186. Alternatively, the reservoir 186 may include multiple separate housings. The reservoir 186 may include at least one fluid level sensor 187 for detecting the fluid level of one or more of the sections of the reservoir 186.

The motor-driven master cylinder (“MC” or “[primary] power transmission unit”) 182 (which may be a dual-chamber type master cylinder 182, also known as a tandem power transmission unit) of the brake system 178 functions as a source of pressure to provide a desired pressure level to the hydraulically operated wheel brakes 180 during a typical or normal non-failure brake apply. An example of a suitable MC 182 arrangement is disclosed in co-pending U.S. patent application Ser. No. 17/708,070, filed 30 Mar. 2022 and titled “Tandem Power Transmission Unit and Brake Systems Using Same” (attorney docket no. 211835-US-NP), which is incorporated by reference herein in its entirety for all purposes. The master cylinder 182 is operable during a normal non-failure braking mode by actuation of an electric motor 190 of the master cylinder 182 to generate brake actuating pressure at first and second MC outputs 192 and 194, respectively, for hydraulically actuating the first and second pairs of wheel brakes 180.

After a brake apply, fluid from the wheel brakes 180 may be returned to the master cylinder 182 and/or be diverted to the reservoir 186. It is also contemplated that other configurations (not shown) of the brake system 178 could include hydraulic control of just selected one(s) of the wheel brakes (with the others being electrically controlled/actuated). One of ordinary skill in the art would be readily able to provide such an arrangement for a desired use environment, following aspects of the present invention.

A secondary brake module is configured for selectively providing pressurized hydraulic fluid at first and second pump outputs 196 and 198, respectively, for actuating the first and second pairs of wheel brakes 180 in at least one of a normal non-failure braking mode and a backup braking mode. As shown in FIG. 10, the secondary brake module includes at least one pump piston 200 associated with at least one wheel brake 180 of the plurality of wheel brakes 180. The pump piston 200 is driven by an eccentric bearing (not shown) on a shaft of an electric pump motor 202 (as differentiated from the electric motor 190 included in the master cylinder 182) which transmits rotary motion to each pump piston 200 for selectively providing pressurized hydraulic fluid to an iso/dump control valve arrangement of at least one wheel brake 180 which is associated with the pump piston 200. FIG. 10 shows one pump piston 200 as being associated with two wheel brakes 180, for a total of two pump pistons 200 in the brake system 178. Together, the pump piston(s) 200 and electric pump motor 202 can be considered to comprise a secondary brake module (A.K.A. “secondary power transmission unit”) of the brake system 178. For example, the two pump pistons 200 shown in the Figures may provide pressurized hydraulic fluid at first and second pump outputs 196 and 198, respectively, to the corresponding wheel brakes 180 via the corresponding iso/dump control valve arrangements (when present), to actuate the first and second pairs of wheel brakes 180 in at least one of a normal non-failure braking mode and a backup braking mode. Each of the first and second pump outputs 196 and 198 can provide fluid to a corresponding one of the first and second pairs of wheel brakes 180. It is contemplated that a plurality of pump pistons 200 could be associated with each of the first and second pump outputs 196 and 198, in some configurations of the brake system 178.

The secondary brake module of the brake system 178 may function as a source of pressure to provide a desired pressure level to selected ones of the wheel brakes 180 in a backup or “failed” situation, when, for some reason, the master cylinder 182 is unable to provide fluid to those selected wheel brakes 180. Accordingly, the secondary brake module may be directly fluidly connected to the reservoir 186, for exchanging hydraulic fluid between these components without having to route the fluid through a (potentially failed) motor-driven master cylinder 182 or another structure of the brake system 178.

The secondary brake module can be used to selectively provide hydraulic fluid to at least one of the wheel brakes 180 in a backup braking mode, but also in an enhanced braking mode, which can occur on its own and/or concurrently with either the backup braking mode or a non-failure normal braking mode. Examples of suitable enhanced braking mode functions available to the brake system 178 may include, but not be limited to, “overboost” (in which higher pressure is provided to a particular brake than would normally be available from the master cylinder 182 alone) and “volume-add” (in which more fluid is provided to a particular brake than would normally be available from the master cylinder 182). These enhanced braking modes may be facilitated, in some use environments, by the pump piston(s) 200. For example, in at least one of the normal non-failure braking mode and the backup braking mode, the secondary brake module can then supply boosted-pressure (above what was obtained from the master cylinder 182) hydraulic fluid to at least one of the first and second pump outputs 196 and 198.

The brake system 178 shown in FIG. 10 also includes at least one electronic control unit (“ECU”) 210, for controlling at least one of the master cylinder 182 and the secondary brake module (via electric pump motor 202) responsive to at least one brake pressure signal, with first and second ECUs 210A, 210B being shown and described herein. The ECUs 210A, 210B may include microprocessors and other electrical circuitry. The ECUs 210A, 210B receive various signals, process signals, and control the operation of various electrical components of a corresponding brake system 178 in response to the received signals, in a wired and/or wireless manner. The ECUs 210A, 210B can be connected to various sensors such as the reservoir fluid level sensor(s) 187, pressure sensors, travel sensors, switches, wheel speed sensors, and steering angle sensors. The ECUs 210A, 210B may also be connected to an external module (not shown) for receiving information related to yaw rate, lateral acceleration, longitudinal acceleration of the vehicle, or other characteristics of vehicle operation for any reason, such as, but not limited to, controlling the brake system 100 during vehicle braking, stability operation, or other modes of operation. Additionally, the ECUs 210A, 210B may be connected to the instrument cluster for collecting and supplying information related to warning indicators such as an ABS warning light, a brake fluid level warning light, and a traction control/vehicle stability control indicator light. It is contemplated that at least one of the ECUs 210A and 210B may be, for example, integrated with the master cylinder 182 or the electric pump motor 202.

The first and second ECUs 210A and 210B may divide the control tasks for the brake system 100 in any desired manner, and may be readily configured by one of ordinary skill in the art for a particular use environment of a brake system, though it is contemplated that any control tasks performed by one or more ECUs 210 will be accomplished responsive to at least one brake pressure signal and/or a braking signal produced by the deceleration signal transmitter 184. For example, the first ECU 210A may be operative to control the electric motor 190 of the master cylinder 182. The second ECU 210B may be operative to control the electric pump motor 202, and potentially, as will now be discussed, at least one of the iso/dump control valve arrangements and at least one of the first and second traction control iso valve.

An iso/dump control valve arrangement is shown in FIG. 10 as being associated with each wheel brake 180 of the plurality of wheel brakes 180. Each iso/dump control valve arrangement includes an iso valve 212 and a dump valve 214, for providing desired fluid routing to an associated wheel brake 180. The reservoir 186 is hydraulically connected to the master cylinder 182 and to each of the iso/dump control valve arrangements, such as via the return line 216. The iso/dump control valve arrangements each include respective serially arranged iso and dump valves 212 and 214. The normally open iso valve 212 for each iso/dump control valve arrangement is located hydraulically between a respective wheel brake 180 and the master cylinder 182 and the normally closed dump valve 214 for each iso/dump control valve arrangement is located hydraulically between a respective wheel brake 180 and the reservoir 186, for the corresponding wheel brake 180.

The iso/dump control valve arrangements may selectively provide slip control to at least one wheel brake 180 powered by the master cylinder 182 and/or the secondary brake module previously mentioned. More broadly, the iso/dump control valve arrangement, and/or other valves of the brake system 178, any of which may be solenoid-operated and have any suitable configurations, can be used to help provide controlled braking operations, such as, but not limited to, ABS, traction control, vehicle stability control, dynamic rear proportioning, regenerative braking blending, and autonomous braking.

A first traction control iso valve 218 is hydraulically interposed between the master cylinder 182 and at least one iso/dump control valve arrangement via the first MC output 192. A second traction control iso valve 220 is hydraulically interposed between the master cylinder 182 and at least one iso/dump control valve arrangement via the second MC output 194. As shown in FIG. 10, it is contemplated that an iso/dump control valve arrangement may be associated with each wheel brake 180 of the first and second pairs of wheel brakes. The first traction control iso valve 218 is hydraulically interposed between the motor-driven master cylinder 182 and the iso/dump control valve arrangements of the first pair of wheel brakes 180. Similarly, the second traction control iso valve 220 is hydraulically interposed between the motor-driven master cylinder 182 and the iso/dump control valve arrangements of the second pair of wheel brakes 180.

As can be seen, each iso/dump control valve arrangement in the brake system 178 of FIG. 10 is in direct or indirect fluid communication with both a selected one of the first and second MC outputs 192 and 194 and a selected one of the first and second pump outputs 196 and 198 for selectively receiving pressurized fluid therefrom, such as during different braking modes or otherwise as desired. One of ordinary skill in the art will be readily able to configure a brake system 178 for any particular use application as desired.

A brake pressure signal is at least one input that an ECU 210 may consider and responsively control one or more other components of the brake system 178, to achieve desired braking results for a particular use environment. One potential source of the brake pressure signal is a brake pressure sensor. For example, and as shown in the Figures, the brake system 178 can include at least one, such as at least two, brake pressure sensors 222. As can be seen in FIG. 10, a first brake pressure sensor 222A may be interposed hydraulically between a selected iso/dump control valve arrangement and a corresponding rear brake of a chosen one of the first and second pairs of wheel brakes 180, and a second brake pressure sensor 222B may be interposed hydraulically between an other iso/dump control valve arrangement and a corresponding rear brake of an other one of the first and second pairs of wheel brakes 180. Either along with or instead of the first and second brake pressure sensors 222A, 222B, a third brake pressure sensor 222C may be interposed hydraulically between the first traction control iso valve 218 and the master cylinder 182, and/or a fourth brake pressure sensor 222D may be interposed hydraulically between the second traction control iso valve 220 and the master cylinder 182. One of ordinary skill in the art can readily provide a desired number/position/type of pressure sensors 138 for a particular brake system 100.

In the brake system 100 of FIG. 1, a single return line 216 places the reservoir 186 and each pump piston 200 in hydraulic connection. The brake system 178 also includes a pump inlet attenuator 224 interposed hydraulically between the reservoir 186 and the pump pistons 200 for “smoothing” fluid flow therebetween. The pump inlet attenuator 224 is in direct fluid connection with the reservoir 186 via the single return line 216 and regulates pressure in the single return line 216 to reduce pressure fluctuations at an inlet side of each pump piston 200 via solely mechanical pressure attenuation. At least a portion of the pump inlet attenuator 224 may be in fluid communication with an ambient space outside the brake system 178 as desired. The pump inlet attenuator 224 may be a single pump inlet attenuator 224 as shown and discussed herein, or it is contemplated that multiple pump inlet attenuators (not shown) may be provided for certain use environments of the brake system 178.

Known brake systems require the column of fluid in the return line 216 to accelerate and decelerate due to the flow ripple generated at the inlets of the pump pistons 202. This causes undesirable pressure ripple and decreased pump volumetric efficiency. Conversely, presence of the pump inlet attenuator 224 facilitates improved pump build rate performance with a smaller-diameter and/or longer return line 216. The pump inlet attenuator 224 (A.K.A., “pump inlet damper”) can be packaged inline in the return line 216 (e.g., in a reservoir hose adapter of the brake system 178) or “piggybacked” in a housing body structure of another component (e.g., a secondary brake module). Since the pump pistons 200 of the brake system 178 pull relatively low-pressure fluid from the return line 216 (within which the pump inlet attenuator 224 is inline), the pump inlet attenuator 224 does not need to be able to withstand the relatively high pressures developed in conduits sourced from the master cylinder 182. Thus, the pump inlet attenuator 224 can service both/all of the pump pistons 200 concurrently, but still with relatively inexpensive (e.g., molded plastic) components since the pump inlet attenuator 224 is operating in a low-pressure environment, as shown.