Exhaust valve and brake system using same

Abstract

The invention relates to an exhaust valve and a brake system using the same. The vent valve includes a bore. An MC valve passage is in fluid communication with the bore. An exhaust fluid passage is in fluid communication with the bore at a location spaced from the MC valve passage. The SCA valve passage is in fluid communication with the bore at a location between the MC valve passage and the exhaust fluid passage. The exhaust valve shuttle moves between a first shuttle position and a second shuttle position at least partially responsive to fluid pressure. Displacement of the exhaust valve shuttle toward the second shuttle position urges air from the bore into the ambient space via the exhaust fluid passage.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 450,461, filed on March 7, 2023, Application No. 63 / 449,670, filed on March 3, 2023, and Application No. 63 / 449,464, filed on March 2, 2023, the subject matter of all of which are incorporated herein by reference in their entirety for all purposes.

[0003] This application is related to technology disclosed in one or more of the following patent applications, namely: U.S. Provisional Patent Application No. [Pending] (Attorney Docket No. 300063-US-PSP [3]) and entitled “PUSH-TYPE SCA” filed concurrently with the present application; U.S. Patent Application No. 18 / 447,490 (Attorney Docket No. 300080-US-NP) and entitled “BRAKING SYSTEM WITH MASTER CYLINDER AND SINGLE CORNER ACTUATOR” filed concurrently with the present application; U.S. Patent Application No. 18 / 447,541 (Attorney Docket No. 300100-US-NP) and entitled “BRAKING SYSTEM WITH MASTER CYLINDER AND SINGLE CORNER ACTUATOR” filed concurrently with the present application and entitled “BRAKING SYSTEM WITH MOTOR DRIVEN MASTER CYLINDER AND ELECTRIC AUXILIARY POWER TRANSFER UNIT”; U.S. patent application Ser. No. 18 / 447,566 (Agent Docket No. 300510-US-NP) filed concurrently with the present application and entitled “BRAKING SYSTEM WITH MOTOR DRIVEN MASTER CYLINDER AND WHEEL SIDE PRESSURE SENSOR”; and U.S. patent application Ser. No. [Pending] (Agent Docket No. 301149-US-NP) filed concurrently with the present application and entitled “Bleed Valve and Braking System Using the Bleed Valve”; the entire contents of all of these are incorporated herein by reference for all purposes. Technical Field

[0004] The present invention relates to a device and method for using a purge valve, and more particularly, to a purge valve and a method and apparatus for a brake system using the purge valve. Background Art

[0005] The braking system may include an anti-lock control device, which includes a hydraulic brake pressure generator, a brake pressure modulator, a sensor for determining the wheel rotation behavior, and an electronic circuit for processing the sensor signal and for generating a brake pressure control signal, the brake pressure modulator being arranged in a pressure fluid conduit between the brake pressure generator and the wheel brakes and being used to change the brake pressure by changing the volume of a chamber containing hydraulic fluid. The braking system may also include an anti-lock control device and a traction slip control device, which may use the brake pressure modulator to control vehicle braking.

[0006] Descriptions of prior art braking systems are found in the following patents, namely: U.S. Patent No. 10730501, issued to Blaise Ganzel on August 4, 2020, and entitled “Vehicle Braking System with Auxiliary Pressure Source”; U.S. patent application published on October 1, 2020, filed by Blaise Gangel, with publication number 2020 / 0307538 and entitled “Braking System with Multiple Pressure Sources”; and U.S. patent application serial number 17 / 400250 filed by Blaise Ganzel on August 12, 2021, and entitled “Apparatus and method for controlling a hydraulic braking system including manual push,” all of which are incorporated herein by reference in their entirety for all purposes. Summary of the invention

[0007] In one aspect, an exhaust valve is described. An elongated exhaust valve bore has a first bore end and a second bore end spaced longitudinally apart, wherein a bore cavity extends between the first bore end and the second bore end. The exhaust valve bore is at least partially defined by an exhaust valve body. An MC valve channel is in fluid communication with the bore cavity near the first bore end. The MC valve channel is configured to selectively place the bore cavity in fluid communication with a master cylinder to selectively transmit pressurized hydraulic fluid through the exhaust valve. An exhaust fluid channel is in fluid communication with the bore cavity at a position longitudinally spaced apart from the MC valve channel. An SCA valve channel is in fluid communication with the bore cavity at a position longitudinally between the MC valve channel and the exhaust fluid channel. The SCA valve channel is configured to selectively place the bore cavity in fluid communication with a single turn actuator that selectively transmits pressurized hydraulic fluid along a valve fluid path extending through a portion of the bore cavity and connecting the MC valve channel and the SCA valve channel and through the exhaust valve. An elongated exhaust valve shuttle extends partially through the bore for selective longitudinal reciprocation at least partially between the first shuttle position and the second shuttle position, between the first end and the second bore end, at least partially in response to fluid pressure along the valve fluid path. The exhaust valve shuttle has a first shuttle end and a second shuttle end spaced longitudinally apart, wherein the second shuttle end is selectively longitudinally located adjacent to the second bore end. A valve ball is located in the valve bore and longitudinally between the exhaust valve shuttle and the first bore end. The valve ball selectively engages a valve seat defined by the valve bore to selectively block the valve fluid path in response to a predetermined fluid pressure at the SCA valve passage and to maintain the valve fluid path in response to at least one of the predetermined fluid pressure at the SCA valve passage and the predetermined fluid pressure at the MC valve passage. In response to the presence of a predetermined hydraulic pressure level within the bore along the exhaust valve fluid path, the exhaust valve shuttle is longitudinally displaced toward the second shuttle position. Displacing the exhaust valve shuttle toward the second shuttle position is used to push air from the bore into the ambient space via the exhaust fluid passage. The valve ball engages the valve seat at least partially in response to displacement of the exhaust valve shuttle toward the second shuttle position. Displacing the exhaust valve shuttle toward the first shuttle position is used to push air from the ambient space into the bore via the exhaust fluid passage. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a better understanding, reference may be made to the accompanying drawings, in which:

[0009] Figure 1 is a schematic cross-sectional view of an exhaust valve in a first configuration according to one aspect of the present invention;

[0010] Figure 2 The first brake system includes Figure 1 Schematic hydraulic diagram of the exhaust valve;

[0011] Figure 3 Is the first brake system component in Figure 4 A detailed view taken at area "3" of FIG. 1 ; and

[0012] Figure 4 The second brake system includes Figure 1 Schematic hydraulic diagram of the exhaust valve. DETAILED DESCRIPTION

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0014] The present invention comprises, consists of or consists essentially of the following features in any combination.

[0015] Figure 1 A cross-sectional view of an exhaust valve 100 is schematically shown. The elongated exhaust valve hole 102 has a first hole end 104 and a second hole end 106 that are longitudinally spaced apart. The term "longitudinal" is used herein to refer to a direction that coincides with the exhaust valve hole 102, which is in the direction of Figure 1 is generally vertical in orientation and is composed of Figure 1 The bore 108 extends between the first bore end 104 and the second bore end 106 . The exhaust valve bore 102 is at least partially defined by an exhaust valve body 110 .

[0016] MC valve passage 112 is in fluid communication with bore 108 near first bore end 104. MC valve passage 112 is configured to selectively place bore 108 in fluid communication with a master cylinder to selectively transmit pressurized hydraulic fluid through exhaust valve 100, as will be discussed below. Exhaust fluid passage 114 is in fluid communication with bore 108 at a location longitudinally spaced apart from MC valve passage 112. SCA valve passage 116 is in fluid communication with bore 108 at a location longitudinally between MC valve passage 112 and exhaust fluid passage 114. SCA valve passage 116 is configured to selectively place bore 108 in fluid communication with a single turn actuator that selectively transmits pressurized hydraulic fluid through exhaust valve 100, as will be discussed below. Pressurized hydraulic fluid may travel “forward” or “rearward” along a valve fluid path (shown schematically at 118 ) that extends through a portion of bore 108 and connects MC valve passage 112 and SCA valve passage 116 .

[0017] The elongated exhaust valve shuttle 120 extends partially through the bore 108 for selective longitudinal reciprocation at least partially between the first bore end 104 and the second bore end 106 between a first shuttle position and a second shuttle position. Figure 1 106). The longitudinal reciprocating motion occurs at least in part in response to fluid pressure along the valve fluid path 118. The exhaust valve shuttle 120 has longitudinally spaced first and second shuttle ends 122 and 124, respectively, wherein the second shuttle end 124 is selectively located longitudinally adjacent the second bore end 106.

[0018] The exhaust valve shuttle 120 may include a shuttle cavity 126 extending into the second shuttle end 124. When present, the shuttle cavity 126 may at least partially contain a spring 128 that urges the exhaust valve shuttle 120 toward the first shuttle position (i.e., Figure 1 ) as shown in the figure.

[0019] The valve ball 130 is located in the valve bore 102 and is longitudinally interposed between the exhaust valve shuttle 124 and the first bore end 104. The valve ball 130 selectively engages a valve seat 132 defined by the valve bore 102 to selectively block the valve fluid path 118 in response to a predetermined fluid pressure at the SCA valve passage 116. For some use environments, the predetermined fluid pressure will be slightly above atmospheric pressure, for example, it may be approximately 1 bar. When the valve ball 130 (selectively) disengages from the valve seat 132 in response to a higher fluid pressure at the SCA valve passage 116 than at the MC valve passage 112, the pressure along the valve fluid path 118 is quickly equalized, and the MC valve passage 112 remains in fluid communication with the SCA valve passage 116 unless the fluid pressure at the SCA valve passage 116 is higher than the predetermined fluid pressure (e.g., approximately 1 bar) that may cause the valve ball 130 to return to the valve seat 132.

[0020] During use of the exhaust valve 100, the valve ball 130 may lift off the valve seat 132 to allow fluid to flow past the valve seat 132 along the valve fluid path 118 from the SCA valve passage 116 toward the MC valve passage 112 in response to a predetermined cracking pressure differential. The valve ball may be spring biased into contact with the valve seat 132, such as by the presence of a ball spring 134. In some use environments, the ball spring 134 may be relatively weak, such as by primarily performing a "detent" function to prevent the valve ball 130 from accidentally disengaging from the valve seat 132 during movement of the exhaust valve 100 - in which case the "cracking" pressure differential will be very low. Conversely, if the ball spring 134 is selected to bias the valve ball 130 strongly toward the valve seat 132, the pressure of the SCA valve passage 116 may need to be significantly higher than the pressure of the MC valve passage 112 in order for the valve ball 130 to allow fluid to flow along the valve fluid path 118. One of ordinary skill in the art can readily “tune” the desired response of the exhaust valve 100 fluid dynamics by selecting the spring 128 , the ball spring 134 , or any other component of the exhaust valve 100 accordingly.

[0021] The exhaust valve body 110 may include an outer surface having at least one sealing groove 140 extending around its circumference. When the exhaust valve body 110 is retained within the brake system housing bore 142 of the brake system housing block 144, as will be discussed below, the at least one sealing groove 140 may include an elastic sealing member 146 that is laterally interposed between the brake system housing bore 142 and the exhaust valve body 110, thereby substantially blocking the fluid passage therebetween and through the elastic sealing member 146. The term "laterally" is used herein to refer to a direction that is generally perpendicular to the longitudinal direction. As shown in the figure, the cross-section of the at least one sealing ring 140 can be circular, oval, curved or curved, and can be configured so that the cross-section is generally symmetrical, thereby blocking fluid from traveling therethrough in two longitudinal directions.

[0022] Similar to "sealing" or otherwise controlling the presence of fluid at various locations within the exhaust valve 100, at a portion of the exhaust valve shuttle 120 longitudinally located between the SCA hydraulic passage 116 and the exhaust fluid passage 114, at least one shaped sealing ring 148 may be laterally interposed between the exhaust valve shuttle 120 and the inner wall 150 of the bore 108. When present, the shaped sealing ring 148 may be used to prevent passing air from the exhaust fluid passage 114 area toward the SCA hydraulic passage 116 area. Thus, the shaped sealing ring 144 may have a directional cross-sectional configuration similar to known lip seals or "L" seals, such as those of the shaped sealing ring 148. Figure 1, with its "skirt" portion flaring outwardly from the exhaust valve shuttle 120. While an elastomeric sealing ring having a more symmetrical cross-sectional shape (similar to sealing ring 146) may be provided in the position of the shaped sealing ring 148 shown, such a "lip seal" type shaped sealing ring 148 may be more durable and reliable for the repeated reciprocating motion carried by the exhaust valve shuttle 120. Additionally, the shaped sealing ring 148 may have a desired level of friction that is lower than that of a more symmetrical shaped sealing ring (e.g., sealing ring 146), which helps reduce shuttle pressures of the exhaust valve 100 compared to using symmetrical sealing rings.

[0023] like Figure 1 As shown in , the exhaust valve body 110 can be a two-piece construction including a first valve body portion 136 that is longitudinally aligned with a second valve body portion 138, which can be used to provide advantages in terms of cost, manufacturing, assembly, operation, or any other reason. When a two-piece exhaust valve body 110 is provided, the first body portion 136 can define the valve seat 132, and the second body portion 138 can define the SCA valve passage 116 and the exhaust fluid passage 114. Similar to the device, when the exhaust valve body 110 is a one-piece component, the two-piece exhaust valve body 110 (such as Figure 1 Each of the first main body portion 136 and the second main body portion 138 in the embodiment shown in the drawings may include an outer surface having a sealing groove 140 extending circumferentially therearound, each sealing groove 140 being configured to include an elastic seal 146 that is laterally interposed between the brake system housing hole 142 and the exhaust valve body 110 to substantially block the fluid passage therethrough.

[0024] However, it is contemplated that, regardless of the number of subcomponents (if any) comprising the valve body 110, any desired sealing grooves and corresponding resilient sealing members may be provided to assist in positioning and sealing the various components and operations of the exhaust valve 100 as desired, and may be readily provided by a person of ordinary skill in the art.

[0025] In the two-piece exhaust valve body 110, the first body portion 136 may have an average outer diameter that is smaller than the average outer diameter of the second body portion 138. Figure 1 Here, the first body portion 136 is at least partially inserted into the second body portion 138 (via Figure 1 Thus, the brake system housing bore 142 is "stepped" in that it has a variable internal profile shape to accommodate the relative outer diameters of the first and second body portions 136, 138 retained therein.

[0026] Refer again Figure 1, it can be seen that the first body portion 136 of the two-piece exhaust valve body 110 can include a laterally extending lip 152. When present, the lip 152 can be longitudinally interposed (or "sandwiched") between the second body portion 138 and the edge region 154 of the stepped brake system housing bore 142 to hold the first body portion 136 in place within the brake system housing bore 142. For example, this can help facilitate assembly by enabling the "ball valve" first body portion 136 of the exhaust valve 100 (including the valve ball 130 and valve seat 132) to be provided as a "closed" one-piece sub-component that drops into the already machined brake system housing bore 142. The second body portion 138 (including the exhaust valve shuttle 120) can then be inserted on top of the already seated first body portion 136. One of ordinary skill in the art can readily provide an appropriately configured exhaust valve 100 for the desired assembly and operating characteristics for a particular use environment.

[0027] At least one filter member 156 can be positioned along the valve fluid path 118. For example and as Figure 1 As shown in FIG, the filter member 156 is retained in a recess at the first bore end 104 of the exhaust valve bore 102, which may provide certain assembly advantages. However, it is contemplated that the filter member may be located in the MC hydraulic passage 112, the SCA hydraulic passage 116, or at any other desired location along the valve fluid path 118.

[0028] An exhaust filter (shown schematically at 158) may be located at any point along the exhaust fluid path or in fluid communication with the exhaust fluid path. When present, the exhaust filter 158 may be configured to allow airflow while substantially preventing liquid from flowing therethrough. For example, a Gore-Tex®-based system, at least in part, available from WL Gore & Associates, Inc. of Newark, Delaware, may be used to filter the exhaust gas. TM A thin film is formed that can be stretched across the “mouth” of the exhaust fluid passage (or an extension thereof) adjacent to the ambient space outside the brake system housing block 144 .

[0029] The exhaust valve cover 160 can selectively block the brake system housing hole 142 adjacent to the second hole end 106. Figure 1As shown in , the exhaust valve cover 160 may include at least a portion of the exhaust valve body 110, and more specifically, may be a portion of the second body portion 138. The brake system housing hole 142 may be adjacent to an outer surface of the brake system housing block 144 located in the ambient space AS. The exhaust valve cover 160 may be mechanically engaged with the inner wall of the brake system housing hole 142 to prevent egress from the brake system housing block 144. For example, this may be achieved by riveting or crimping the exhaust valve cover 160 into the brake system housing frame 144 after the components of the exhaust valve 100 are placed in the brake system housing block 144.

[0030] In at least partially summarizing the configuration and maintenance of the exhaust valve 100 within the brake system housing block 144, it should be noted that at a portion of the exhaust valve shuttle 120 longitudinally located between the SCA hydraulic passage 116 and the exhaust fluid passage 114, at least one formed seal ring 148 is laterally interposed between the exhaust valve shuttle 120 and the inner wall of the bore 108. In addition, an elastomeric seal member 146 is laterally interposed between the brake system housing bore 142 and the exhaust valve body 110, thereby substantially blocking the fluid passage therethrough. As a result, and as shown in FIG. Figure 1 It can be seen that at least one formed sealing ring 148, the exhaust valve body 110 and the elastic seal 146 jointly separate the exhaust valve 110 into a wet valve area and a dry valve area, wherein the wet valve area is located longitudinally between the formed sealing ring 148 and the first hole end 104 and is configured to selectively accommodate hydraulic fluid, while the dry valve area is located longitudinally between the formed sealing ring 148 and the second hole end 106 and is configured to be substantially free of hydraulic fluid. (Here, the term "substantially free of hydraulic fluid" allows for a small amount of hydraulic fluid to inadvertently penetrate or intrude into the "dry valve area" in an amount that has little effect on the operation of the exhaust valve 100 or a larger brake system. Additionally, some grease or other substances can be applied to the "dry valve area" side of the formed sealing ring 148 without destroying the "dry" nature of this portion of the exhaust valve 100) This separation is respectively Figure 1 The exhaust valve 100 is shown as being divided equally between a dotted line on the “W” side and a dotted line on the “D” side.

[0031] Then, in operation, the exhaust valve shuttle 120 can be longitudinally displaced toward the second shuttle position in response to a predetermined hydraulic pressure level present within the bore 108 along the exhaust valve fluid path 118. The second shuttle position is not Figure 1 1, but will include a second shuttle end 124 that is proximate to, and optionally in contact with, the second bore end 106. This displacement of the exhaust valve shuttle 124 toward the second shuttle position serves to remove air from the bore (more specifically, from the Figure 1The valve ball 130 is engaged with the valve seat 132 at least partially in response to the displacement of the exhaust valve shuttle 124 toward the second shuttle position.

[0032] Conversely, the exhaust valve shuttle 124 is moved toward the first shuttle position (eg, Figure 1 14. The displacement of the valve ball 130 from the valve seat 132 may be used to push air from the ambient space into the bore 108 (into the dry valve area "D") via the exhaust fluid passage 114. When the exhaust valve shuttle 120 is pushed upward to the first shuttle position under the influence of hydraulic fluid pressure from the SCA hydraulic passage 116, the "bump" or short post 162 at the first shuttle end 122 may be used to push the valve ball 130 upward out of engagement with the valve seat 132, thereby allowing fluid to flow along the valve fluid path 118.

[0033] Thus, as described above, the exhaust valve 100 may facilitate "breathing" of the brake system, thereby managing the flow of hydraulic fluid within the brake system in a desired manner.

[0034] A person skilled in the art may easily understand the operation of the exhaust valve 100 after referring to the present disclosure, and may provide a suitable exhaust valve 100 device for a specific use environment.

[0035] Now go to Figures 2 to 4 The first brake system 164 and the second brake system 164' are schematically shown as Figure 1 The exhaust valve 100 provides a use environment. Figure 2 , depicts an exemplary first braking system 164 that is configured to actuate a plurality of wheel brakes 166 including at least a first wheel brake LF and a second wheel brake RF using an exhaust valve 10. Here, the braking system 164 is shown as a hydraulic braking system, in which fluid pressure is utilized to apply a braking force to the braking system 164. The braking system 164 can be applicable to a ground vehicle, such as a motor vehicle having four wheels, each wheel being equipped with a wheel brake. In addition, the braking system 164 can be provided with other braking functions, such as anti-lock braking (ABS) and other anti-skid control functions, to effectively brake the vehicle. The components of the braking system 164 can be housed in one or more blocks or housings. The block or housing can be made of a solid material such as aluminum that is drilled, machined, or otherwise formed to accommodate various components. Fluid conduits can also be formed in the block or housing.

[0036] For example, each of the wheel brakes 166 may include a brake caliper mounted on the vehicle to engage a friction element (e.g., a brake disc) that rotates with the wheel to achieve braking of the associated wheel. The wheel brakes 166 may be associated with any combination of front and rear wheels of the vehicle in which the corresponding brake system 164 is installed. For example, the brake system 164 may be configured as a vertically split or diagonally split system. For the purposes of this specification, the wheel brakes 166 are not distinguished herein, although a person of ordinary skill in the art can easily provide suitable braking devices for a particular use environment.

[0037] The brake system 164 includes a reservoir 168 for storing and maintaining hydraulic fluid for the brake system 164. A manually operated master cylinder 170 is in fluid communication with the reservoir 168 and is used during a backup braking mode to generate pressurized hydraulic fluid at a first MC output 172 and a second MC output 174, respectively, for hydraulically actuating a first wheel brake LF and a second wheel brake RF, respectively. This backup braking mode is referred to as "manual push" and can provide pressurized hydraulic fluid in a known manner when other parts of the brake system 164 are unavailable for some reason. However, it is contemplated that the master cylinder 170 can also or alternatively provide a "normal" resistance and "pedal feel" to the driver in a normal, non-fault braking mode. The master cylinder ("MC") 170 shown in the figure is a dual chamber type master cylinder and can be used to generate pressurized fluid in response to user manipulation (manual force) of a brake pedal 176 mechanically connected to the master cylinder 170.

[0038] The braking system 164 also includes a plurality of single corner actuators ("SCAs") 178. Each single corner actuator 178 is hydraulically interposed between a selected one of the first MC output 172 and the second MC output 174 and a corresponding one of the first wheel brake LF and the second wheel brake RF. Each SCA 178 includes a secondary power transfer unit ("PTU") 180 configured to selectively provide pressurized hydraulic fluid at the SCA output 182 for actuating the corresponding wheel brake in at least one of a normal fail-safe braking mode and a backup braking mode. The secondary PTU 180 includes an electric PTU motor 184 configured to selectively pressurize hydraulic fluid by transferring rotational motion to a plunger assembly 186 of the secondary PTU 180. In certain configurations, such as Figure 2 As shown in , each single corner actuator 178 may be indirectly fluidly connected to the reservoir 168 via the master cylinder 170 .

[0039] At least one two-position three-way valve 188 is included in the SCA 178 and may be hydraulically interposed between the plunger assembly 186 and the corresponding wheel brake LF or RF for selectively controlling the supply of hydraulic fluid from at least one of the plunger assembly 186 or the master cylinder 170 to the corresponding wheel brake LF or RF. Figure 2 and Figure 4 As shown in FIG. 1 , when the three-way valve 188 is de-energized (e.g., if the electrical portion of the brake system 164 fails, or if the following guidance is required), the three-way valve 88 guides the pressurized hydraulic fluid from the MC 170 (via the corresponding first MC output 172 or second MC output 174) to the corresponding wheel brake LF or RF. The three-way valve 188 can be energized to guide the pressurized hydraulic fluid from the secondary PTU 180 (via the corresponding SCA output 182) to the corresponding wheel brake LF or RF, such as during a normal, no-failure braking mode.

[0040] Each SCA 178 also includes the aforementioned and Figure 1 1. A selected one of the first MC output end 172 and the second MC output end 174 of the SCA 178 is fluidly connected to the MC hydraulic passage 112, and the SCA hydraulic passage 116 is fluidly connected to the plunger chamber 190 of the corresponding plunger assembly 186. For example, the exhaust valve body 110 can be retained in the brake system housing hole 142 of the brake system housing block 144. The brake system housing block 144 can include: MC housing passage (see Figure 1 ), which places the MC valve passage 112 in fluid communication with the master cylinder 170 (e.g., via respective first and second MC outputs 172 and 174); the SCA housing passage (see Figure 1 ), which places the SCA valve passage 114 in fluid communication with the single-angle actuator 178; and the exhaust housing passage (see Figure 1 VH in, which places the exhaust fluid channel 114 in fluid communication with the ambient space AS.

[0041] At least two brake pressure sensors 190 may be provided for the brake system 164 , wherein each brake pressure sensor 190 is associated with a corresponding wheel brake RF or LF for sensing the hydraulic pressure at the corresponding wheel brake RF or LF and generating a brake pressure signal accordingly.

[0042] At least one electronic control unit ("ECU") 194 may be provided for controlling at least one of the secondary power transfer unit 180 and the two-position three-way valve 188 in response to at least one brake pressure signal, using a first ECU 194A and a second ECU 194B shown and described herein. The ECUs 194A, 194B may include a microprocessor and other circuitry. The ECUs 194A, 194B receive various signals in a wired and / or wireless manner, process the signals, and control the operation of various electrical components of the corresponding brake system 164 in response to the received signals. For example, the ECUs 194A and / or 194B may control at least one of the secondary power transfer unit 180 and the three-way valve 188 in response to a brake signal generated by the brake pedal 176 of the master cylinder 170.

[0043] The ECUs 194A, 194B may be connected to various sensors, such as reservoir level sensors, pressure sensors, travel sensors, switch and wheel speed sensors, and steering angle sensors. The ECUs 194A, 194B may also be connected to an external module (not shown) for receiving information related to the vehicle's yaw rate, lateral acceleration, longitudinal acceleration, or other characteristics of vehicle operation for any reason, such as, but not limited to, controlling the brake system 164 during vehicle braking, stability operations, or other operating modes. Additionally, the ECUs 194A, 194B may be connected to an instrument panel for collecting and supplying information related to warning indicators (e.g., ABS warning lights, brake fluid level warning lights, and traction control / vehicle stability control indicator lights). For example, it is contemplated that at least one of the ECUs 194A and 194B may be integrated into at least one of the secondary PTUs 180.

[0044] When two ECUs are provided for the brake system 164, the first ECU 194A may be used to control the electric PTU motor 184 of the selected SCA 178 and any desired one or more of the three-way valves 188. The second ECU 194B may be used to control the electric PTU motor 184 of another SCA 178 and any desired one or more of the three-way valves 188. A brake system 164 having desired ECU 194 characteristics and redundancy for a particular use environment may be readily provided by one of ordinary skill in the art.

[0045] An example of a suitable ECU 194 device is disclosed in co-pending U.S. patent application Ser. No. 17 / 708,019, filed on March 30, 2022, and entitled “CONTROL DEVICE FOR BRAKING SYSTEM” (Agent Docket No. 211652-US-NP-2, hereinafter referred to as “backup ECU”), the entire contents of which are incorporated herein by reference for all purposes.

[0046] A brake simulator (shown generally at 196) may be coupled to the master cylinder 170 and (optionally directly, such as Figure 2 ) reservoir 168 is hydraulically connected to provide the desired brake pedal response, to assist in directing hydraulic fluid between other components of the brake system 164, or for any other reason. A person skilled in the art can easily configure a suitable brake simulator 196 for a specific use environment.

[0047] The operation of the brake system 164 associated with the exhaust valve 100 will now be discussed in detail. Generally, in response to the hydraulic pressure at the SCA hydraulic passage 116 being at a predetermined fluid pressure (e.g., a pressure greater than about 1 bar), the exhaust valve shuttle 120 is urged toward the second shuttle position. In response to the hydraulic pressure at a selected one of the SCA hydraulic passage 116 (e.g., a pressure less than about 1 bar) and the MC hydraulic passage 112 being at a predetermined fluid pressure, the exhaust valve shuttle 120 is urged toward the first shuttle position (e.g., a pressure less than about 1 bar). Figure 1 ) (as shown in ), for example, this may occur, thereby allowing a portion of the hot expansion fluid in SCA 178 to return to reservoir 168.

[0048] Movement of the exhaust valve shuttle 120 of the exhaust valve 100 into the second shuttle position restricts the flow of hydraulic fluid through the corresponding single turn actuator 178 and correspondingly to the corresponding wheel brake 166, and serves to maintain fluid flow between the master cylinder 170 and the brake simulator 196. That is, the exhaust valve shuttle 120 reciprocates longitudinally between the first shuttle position and the second shuttle position to prevent more than a predetermined amount of pressurized hydraulic fluid from flowing through the SCA 178 and out to the corresponding wheel brake 166, because doing so would cut off the brake simulator 196 from the rest of the brake system 164 due to the travel of certain other plungers and shuttles in other brake system 164 components. When the brake simulator 196 is hydraulically isolated in this manner, even temporarily, the hydraulic fluid within the brake simulator 196 is unavailable to the rest of the brake system 164, and the brake pedal 176 may suddenly become very stiff or "hard," causing user discomfort.

[0049] As another feature of the braking system 164 facilitated by the exhaust valve 100, the valve ball 130 and valve seat 132 may be considered to functionally collectively comprise a "SCA check valve" that is located as part of the exhaust valve 100 in a single turn actuator 178 adjacent to the exhaust valve shuttle 120. When the valve ball 130 and valve seat 132 (and optional ball spring 134) are so defined, the resulting "SCA check valve" is hydraulically interposed between the exhaust valve shuttle 120 and the master cylinder 170 along (i.e., in fluid communication with) the respective first MC output 172 or second MC output 174. The SCA check valve may then cooperate with the exhaust valve shuttle 120, wherein the aforementioned "breathing" function is provided to provide a low pressure release function to the respective single turn actuator 178. Additionally, user release of brake pedal 176 may allow the "SCA check valve" function of bleed valve 100 to operate, e.g., the SCA check valve may be opened by bleed valve shuttle 120 to allow more fluid to refill any "gaps" in SCA 178 or wheel brakes 166 caused by a predetermined amount of brake pad wear, i.e., a so-called "Nürburgring scenario" wherein a vehicle is operated continuously long enough for a predetermined amount of brake pad wear to occur, such that the vehicle is not allowed to be shut down and "cycled" in the well-known manner to refill the brakes.

[0050] The exhaust valve 100 can cause the brake 166 to exhaust to the atmosphere (ambient space AS) at any time when the user does not apply force to the brake pedal 176 without de-energizing the two-position three-way valve 188. Figure 2 and Figure 4 As shown in , the exhaust valve 100 can also be used during manufacturing or maintenance of the brake system 164 in a circuit with a three-way valve 188, without the need for electric exhaust / inflation, and the exhaust valve 100 will not close unless pressure is generated in the brake system 164.

[0051] exist Figure 2 In the brake system 164 of FIG. 1 , an orifice 208 is shown as being hydraulically interposed between the reservoir 168 and a selected chamber in the dual chamber master cylinder 170. The orifice 208 can be used in conjunction with the SCA 178 associated with the selected chamber to energize that chamber and provide a simulator test valve function to the brake system 164. That is, due to the reduced diameter orifice 208, when the corresponding SCA 178 is actuated, the master cylinder 170 is able to perform a self-test without the need for manual push-in.

[0052] Figure 3 Schematically depicts Figure 4Region “3” of the secondary power transfer unit 180 , wherein the plunger 200 of the plunger assembly 186 of the secondary power transfer unit 180 is depicted in a fully retracted position (eg, during a vacuum / fill operation). Figure 3 The shaped sealing ring 148 shown in FIG. 1 blocks fluid flow in both directions and blocks flow from left to right (in FIG. Figure 3 At least one of the shaped seal rings 148 (here, the rightmost one) is carried by the bearing ring 202 of the plunger assembly 186. The SCA fluid path "SCF" is defined as starting from the SCA housing passage SCH, through the hole in the bearing ring 202, and through the orifice 204 of the plunger 200 to place the SCA housing passage SCH in fluid communication with the plunger cavity 190. Once the plunger 200 is in the actuation direction "A" (to the left, as shown in FIG. 1 ), the plunger 200 is moved to the left and right sides of the bearing ring 202. Figure 3 206 of the bearing ring 202 and the outer surface of the plunger 200, and out through the SCA housing passage SCH to the exhaust valve 100. (It should be noted that multiple orifices 204 (e.g., two orifices spaced 180 degrees around the plunger 200) can be provided to increase the chance that one of them is always open.) This situation may occur, for example, when thermal expansion occurs within the plunger cavity 190. Regardless of the reason for the small amount of discharge through the orifice 204 toward the exhaust valve 100, the pressurized hydraulic fluid directed to the exhaust valve 100 can be sufficient to help push the exhaust valve shuttle to the desired shuttle position.

[0053] Each of the single angle actuators 178 may be carried by a corresponding SCA housing (which may be identical to the brake system housing block 144 discussed above, corresponding to the exhaust valve 100) that is supported by a plurality of SCA housings. Figure 2 and Figure 4 The reservoir 168 and the master cylinder 170 may be carried together by a main housing, which may be Figure 1 and Figure 4 The dashed line "P" in FIG. 1 schematically depicts the main housing and each SCA housing may be spaced apart from each other. It is contemplated that each SCA housing may be located adjacent to a corresponding wheel brake RF or LF as desired.

[0054] like Figure 2 and Figure 4As shown in , the braking system 164 may include a third wheel brake and a fourth wheel brake 166, which are labeled LR and RR, respectively. Each of the third wheel brake LR and the fourth wheel brake RR can be actuated by at least one of an electric brake motor 198 and an additional, separately provided single corner actuator (not shown, but generally similar to the SCA 178 discussed above, and shown in the figure as being associated with the first wheel brake LF and the second wheel brake RF). The third and fourth wheel brakes LR and RR and / or the electric brake motor 198 and / or the single corner actuator associated therewith can be housed in a separate rear brake housing ( Figure 2 and Figure 4 Schematically depicted by dashed line "RB" in FIG. 1 ), which may be spaced apart from the main housing and each SCA housing.

[0055] Figure 4 A second exemplary embodiment of a braking system 164 is illustrated. Figure 4 The braking system 164' is similar to Figures 2 to 3 The braking system 164 is therefore similar to the reference Figures 2 to 3 Describes the same or similar structure Figure 4 The structures of the present invention have the same reference numerals, and the "main" mark is added. The description of common elements and operations similar to those in the previously described first embodiment will not be repeated in the second embodiment, but should be considered incorporated by reference below as appropriate.

[0056] exist Figure 4 In the braking system 164 ′, the reservoir 168 ′ is indirectly connected to the brake simulator 196 ′ via one or two dual chambers of the master cylinder 170 . Figure 4 The brake system 164' is shown to include a bleed screw 210 located hydraulically at a high point in the system adjacent to the master cylinder 170. When present, the bleed screw 210 can be selectively operated (e.g., opened) to release air from at least one hydraulic line in the brake system 164' during a maintenance bleed of the brake system. That is, the bleed screw 210 allows air to be exhausted from a secondary circuit corresponding to the second chamber of the master cylinder 170, such as Figure 4 However, the bleed screw 210 will be closed as needed for bleeding / filling, such as during initial construction of the brake system 164' and / or during routine maintenance and repair work.

[0057] It is contemplated that a person skilled in the art may provide various other components, such as electric service and / or parking brake motors, to achieve the desired configuration for a specific use environment in any brake system described herein. For example, although a plurality of filters and pressure sensors are shown in the figures, their detailed description is omitted here for the sake of brevity, because a person skilled in the art will readily understand how to provide the required number, location and / or operation of filters, sensors and any other components according to the needs of the specific use environment of the present invention.

[0058] As used herein, the singular forms "a", "an" and "the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "comprising" used herein may specify the presence of the features, steps, operating elements and / or components, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups thereof.

[0059] As used herein, the term "and / or" may include any and all combinations of one or more of the associated listed items.

[0060] It will be understood that when an element is referred to as being "on," "attached," "connected," "coupled with," "in contact," "adjacent," etc., another element, it may be directly located on or attached to, connected to, coupled to, in contact with, or adjacent to another element, or there may be intermediate elements. Conversely, for example, when an element is referred to as being "directly on," "directly attached," "indirectly connected," "directly coupled with," "directly in contact with," or "directly adjacent to" another element, there are no intermediate elements. One of ordinary skill in the art will also understand that a reference to a structure or feature that is arranged "directly adjacent" to another feature may have a portion that overlaps or is located below an adjacent feature, while a structure or feature that is arranged adjacent to another feature may not have a portion that overlaps or is located below an adjacent feature.

[0061] For ease of description, spatially relative terms, such as "below," "beneath," "lower," and "above," "proximal," "distal," etc., may be used herein to describe the relationship of one element or feature to another element and feature, as illustrated in the figures. It will be understood that in addition to the orientations shown in the figures, spatially relative terms may also include different orientations of the device in use or operation. For example, if the device in the figures is inverted, elements described as "below" or "beneath" other elements or features would be oriented "above" the other elements and features.

[0062] As used herein, the phrase "at least one of X and Y" may be interpreted to include X, Y, or a combination of X and Y. For example, if an element is described as having at least one of X and Y, the element may include X, Y, or a combination of X and Y at a particular time, and the selection may change from time to time. Conversely, the phrase "at least one of X" may be interpreted to include one or more Xs.

[0063] It will be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, without departing from the teachings of the present disclosure, the "first" element discussed below may also be referred to as the "second" element. Unless otherwise specifically stated, the order of operations (or steps) is not limited to the order given in the claims or drawings.

[0064] Although aspects of the present disclosure have been particularly shown and described with reference to the above exemplary aspects, it will be understood by those skilled in the art that various additional aspects may be envisioned. For example, the specific methods of using the apparatus described above are merely illustrative; those skilled in the art may readily determine any number of tools, sequence of steps, or other means / options for placing the above-described apparatus or its components in a substantially similar position as shown and described herein. In order to maintain the clarity of the drawings, some of the repeated components shown are not specifically numbered, but those skilled in the art will implement the element numbering that should be associated with the unnumbered components based on the numbered components; the presence or absence of element numbers in the figures does not mean or imply a distinction between similar components. Any of the structures and components described may be integrally formed as a single integral body or monolithic piece, or composed of separate subcomponents, wherein any of these structures involve any suitable stock or custom components and / or any suitable material or combination of materials. Any of the structures and components described may be disposable or reusable, as required by a particular use environment. Any component may be provided with a user-perceivable mark to indicate the material, configuration, at least one size, etc. associated with the component, and the user-perceivable mark may help the user select a component for a particular use environment from a series of similar components. The "predetermined" state can be determined at any time before the structure being manipulated actually reaches that state, and the "predetermination" is performed at the latest before the structure reaches the predetermined state. The term "substantially" as used herein refers to a quality that is largely but not necessarily entirely a specified quality - the "substantially" quality allows non-quality items to be included in a relatively small range. Although certain components described herein are shown as having specific geometric shapes, all structures of the present disclosure may have any suitable shape, size, configuration, relative relationship, cross-sectional area or any other physical characteristic required for a particular application. Any structure or feature described with reference to one aspect or configuration may be provided to any other aspect or configuration alone or in combination with other structures or features, because it is impractical to describe each aspect and configuration discussed herein as having all the options discussed with respect to all other aspects and configurations. A device or method combining any of these features should be understood to fall within the scope of the present disclosure, as determined based on the following claims and any equivalents thereof.

[0065] Other aspects, objects and advantages can be obtained from a study of the drawings, the disclosure and the appended claims.

Claims

1. An exhaust valve, comprising: an elongated exhaust valve bore having first and second longitudinally spaced bore ends, wherein a bore cavity extends between the first and second bore ends, the exhaust valve bore being at least partially defined by an exhaust valve body; a MC valve passage in fluid communication with the bore proximate the first bore end, the MC valve passage being configured to selectively place the bore in fluid communication with a master cylinder to selectively transmit pressurized hydraulic fluid through the exhaust valve; an exhaust fluid passage in fluid communication with the bore at a location longitudinally spaced from the MC valve passage; an SCA valve passage in fluid communication with the bore at a location longitudinally between the MC valve passage and the exhaust fluid passage, the SCA valve passage being configured to selectively place the bore in fluid communication with a single turn actuator to selectively transmit pressurized hydraulic fluid through the exhaust valve along a valve fluid path extending through a portion of the bore and connecting the MC valve passage with the SCA valve passage; an elongated exhaust valve shuttle extending partially through the bore for selective longitudinal reciprocation between first and second shuttle positions at least partially between the first and second bore ends in response at least in part to fluid pressure along the valve fluid path, the exhaust valve shuttle having longitudinally spaced first and second shuttle ends, wherein the second shuttle end is selectively located longitudinally adjacent the second bore end; and a valve ball located in the valve bore and longitudinally between the exhaust valve shuttle and the first bore end, the valve ball selectively engaging a valve seat defined by the valve bore to selectively block the valve fluid path in response to a predetermined fluid pressure at the SCA valve passage and to maintain the valve fluid path in response to at least one of the predetermined fluid pressure at the SCA valve passage and a predetermined fluid pressure at the MC valve passage; wherein the exhaust valve shuttle is longitudinally displaced toward the second shuttle position in response to a predetermined hydraulic pressure level present within the bore along the exhaust valve fluid path, displacement of the exhaust valve shuttle toward the second shuttle position being operable to push air from the bore into an ambient space via the exhaust fluid passage; wherein the valve ball engages the valve seat at least partially in response to displacement of the exhaust valve shuttle toward the second shuttle position; and Wherein, displacement of the exhaust valve shuttle toward the first shuttle position can be used to push air from the ambient space into the bore through the exhaust fluid passage.

2. The exhaust valve according to claim 1, wherein: The exhaust valve body includes a first body portion and a second body portion, the first body portion is longitudinally aligned with the second body portion, the first body portion defines the valve seat, and the second body portion defines the SCA valve passage and the exhaust fluid passage, and wherein each of the first body portion and the second body portion includes an outer surface having a sealing groove extending circumferentially around the outer surface.

3. The exhaust valve according to claim 2, wherein: The exhaust valve body is held within the brake system housing bore, and each sealing groove includes an elastic sealing member laterally interposed between the brake system housing bore and the exhaust valve body to substantially block a fluid passage therethrough.

4. The exhaust valve according to claim 2, wherein: The first body portion has an average outer diameter that is smaller than an average outer diameter of the second body portion, the first body portion is at least partially inserted into the second body portion, and the brake system housing bore is stepped to accommodate the outer diameters of the first and second body portions held therein.

5. The exhaust valve according to claim 4, wherein: The first body portion includes a laterally extending lip longitudinally interposed between the second body portion and a rim area of ​​the stepped brake system housing aperture to retain the first body portion in place within the brake system housing aperture.

6. The exhaust valve according to claim 1, wherein: The exhaust valve body is retained in the brake system housing hole of the brake system housing block, and the brake system housing block includes an MC housing channel, an SCA housing channel and an exhaust housing channel, the MC housing channel places the MC valve channel in fluid communication with the master cylinder, the SCA housing channel places the SCA valve channel in fluid communication with the single-angle actuator, and the exhaust housing channel places the exhaust fluid channel in fluid communication with the ambient space.

7. The exhaust valve according to claim 1, wherein: The exhaust valve body includes an outer surface having at least one sealing groove extending circumferentially around the outer surface, and the exhaust valve body is retained in a brake system housing hole of a brake system housing block, and the at least one sealing groove includes an elastic sealing member, which is laterally interposed between the brake system housing hole and the exhaust valve body, thereby substantially blocking the passing fluid channel.

8. The exhaust valve according to claim 7, wherein: The exhaust valve cover selectively blocks the brake system housing hole near the second hole end, and the exhaust valve cover is mechanically engaged with the inner wall of the brake system housing hole to prevent separation from the brake system housing block.

9. The exhaust valve according to claim 1, wherein: The valve ball is spring biased into contact with the valve seat, and wherein the valve ball lifts off the valve seat to allow fluid to flow from the SCA valve passage along the valve fluid path toward the MC valve passage in response to a predetermined cracking pressure differential.

10. The exhaust valve of claim 1, comprising at least one filter member positioned along the valve fluid path.

11. The exhaust valve of claim 1, comprising an exhaust filter in fluid communication with the exhaust fluid passage, the exhaust filter being configured to allow air flow therethrough while substantially preventing liquid flow therethrough.

12. The exhaust valve according to claim 1, wherein: At a portion of the exhaust valve shuttle longitudinally between the SCA hydraulic passage and the exhaust fluid passage, at least one shaped sealing ring is laterally interposed between the exhaust valve shuttle and the inner wall of the bore, the shaped sealing ring being operable to prevent passing air from passing toward the SCA hydraulic passage.

13. The exhaust valve according to claim 7, wherein: At a portion of the exhaust valve shuttle longitudinally located between the SCA hydraulic passage and the exhaust fluid passage, at least one shaped sealing ring is laterally interposed between the exhaust valve shuttle and the inner wall of the bore cavity, and wherein the at least one shaped sealing ring, the exhaust valve body and the elastic sealing member cooperate to separate the exhaust valve into a wet valve region and a dry valve region, the wet valve region being longitudinally located between the shaped sealing ring and the first bore end and being configured to selectively accommodate hydraulic fluid, and the dry valve region being longitudinally located between the shaped sealing ring and the second bore end and being configured to be substantially free of hydraulic fluid.

14. The exhaust valve according to claim 1, wherein: The exhaust valve shuttle includes a shuttle cavity extending into the second shuttle end, the shuttle cavity at least partially containing a spring that urges the exhaust valve shuttle toward the first shuttle position.

15. A braking system for actuating a plurality of wheel brakes including at least a first wheel brake and a second wheel brake, the braking system comprising: Liquid reservoir; a master cylinder in fluid communication with the reservoir and operable in a backup braking mode to generate pressurized hydraulic fluid at a first MC output and a second MC output for hydraulically actuating the first wheel brake and the second wheel brake, respectively, in response to user manipulation of a brake pedal mechanically connected to the master cylinder, the master cylinder being a dual chamber master cylinder; a brake simulator in fluid communication with at least one of the first MC output and the second MC output and in fluid communication with the reservoir for providing a predetermined brake pedal response to a user; a plurality of single corner actuators, each single corner actuator being hydraulically interposed between a selected one of the first MC output and the second MC output and a corresponding one of the first wheel brake and the second wheel brake, each single corner actuator comprising: a secondary power transfer unit configured to selectively provide pressurized hydraulic fluid at an SCA output for actuating corresponding wheel brakes in at least one of a normal fail-safe braking mode and a backup braking mode, the secondary power transfer unit including an electric PTU motor configured to selectively pressurize the hydraulic fluid by imparting rotational motion to a plunger assembly of the secondary power transfer unit; at least one two-position, three-way valve hydraulically interposed between the plunger assembly and the corresponding wheel brake for selectively controlling the supply of hydraulic fluid from at least one of the plunger assembly and the master cylinder to the corresponding wheel brake; and The exhaust valve of claim 1, wherein a selected one of the first MC output and the second MC output is in fluid communication with the MC hydraulic passage, and the SCA hydraulic passage is in fluid communication with a plunger chamber of the plunger assembly, wherein in response to the hydraulic pressure at the SCA hydraulic passage being at a predetermined fluid pressure, the exhaust valve shuttle is urged toward the second shuttle position, and wherein in response to the hydraulic pressure at the selected one of the SCA hydraulic passage and the MC hydraulic passage being at a predetermined fluid pressure, the exhaust valve shuttle is urged toward the first shuttle position; at least two brake pressure sensors, each brake pressure sensor being associated with a respective wheel brake for sensing hydraulic pressure at the respective wheel brake and responsively generating a brake pressure signal; and an electronic control unit for controlling at least one of the secondary power transfer unit and the master cylinder in response to at least one brake pressure signal; Each single-angle actuator is indirectly fluidically connected to the reservoir via the master cylinder.

16. The brake system of claim 15, comprising a third wheel brake and a fourth wheel brake, each of the third wheel brake and the fourth wheel brake being actuated by at least one of an electric brake motor and a single corner actuator.

17. The braking system according to claim 15, wherein: Each of the single angle actuators is carried by a respective SCA housing, the reservoir and the master cylinder are carried together by a main housing, and the main housing and each SCA housing are spaced apart from one another.

18. The brake system according to claim 15, wherein: Movement of the exhaust valve shuttle of the exhaust valve into the second shuttle position restricts flow of hydraulic fluid through the respective single turn actuator and hence to the respective wheel brake and can serve to maintain fluid flow between the master cylinder and the brake simulator.

19. The braking system according to claim 15, wherein: The valve ball and valve seat together include an SCA check valve located in the single-turn actuator, the SCA check valve being adjacent to the exhaust valve shuttle and being part of the exhaust valve, the SCA check valve being hydraulically inserted between the exhaust valve shuttle and the master cylinder along the corresponding first MC output end or the second MC output end, the SCA check valve cooperating with the exhaust valve shuttle to provide a low-pressure relief function to the corresponding single-turn actuator.

20. The braking system according to claim 15, wherein: The reservoir is indirectly connected to the brake simulator, and the brake system includes a bleed screw adjacent to the master cylinder and hydraulically located at a high point in the system, the bleed screw being selectively operable to release air from at least one hydraulic line of the brake system during maintenance bleeding of the brake system.

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