A brake-by-wire module comprising a pressure balanced piston and a backup pump assembly for a wet ball screw

Abstract

The present disclosure provides a line control brake module of a pressure balanced piston and backup pump assembly containing a wet ball screw. An electro-hydraulic brake system includes a master cylinder (MC) configured to supply fluid into a first master cylinder fluid passage in response to a pressing force on a brake pedal, a pressure supply unit (PSU) assembly having a PSU motor coupled to a ball screw actuator, a PSU housing defining a piston bore having distal ends opposite the PSU motor, and a PSU piston dividing the piston bore into a first chamber and a second chamber, each of the first chamber and the second chamber containing hydraulic fluid, and a backup pump assembly including a pump supplying brake fluid to at least one wheel brake. The ball screw actuator includes an actuator nut assembly having a plurality of ball bearings, each of the plurality of ball bearings disposed within the piston bore and immersed in the hydraulic fluid.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to brake systems for vehicles, such as automobiles. More particularly, the present disclosure relates to a brake-by-wire system having a pressure supply unit (PSU) with a pressure balance piston. BACKGROUND

[0002] As electric and hybrid vehicles continue to proliferate in markets around the world, it is well known that significant extension of battery range can be obtained by harnessing the motor-generator power generation capability of the device during braking. However, the input torque in generator mode used to recharge the battery is not coincident with the driver input function of pedal force / travel vs. vehicle deceleration. To achieve this complex function, the hydraulic brake portion of the vehicle must provide the difference between the generator braking torque and the driver demanded braking torque.

[0003] For many years, the engineering community has understood this requirement, often referred to as regenerative braking blending. The most effective way to achieve this is to use a “brake-by-wire” technology. To achieve this, the brake pedal effectively becomes a joystick, so it must be connected to a travel and / or force sensor to send a signal to the system ECU which interprets this as the driver’s intention to decelerate the vehicle. In addition, the brake pedal “feel” must be simulated by an appropriate force-travel relationship, and this brake pedal “feel” must also have the ability to be isolated from the direct application of the master cylinder to the wheel brake portion.

[0004] Brake-by-wire systems typically include a pressure supply unit (PSU) to provide a supply of pressurized fluid for actuating the wheel brake portion.

[0005] One of the key factors involved in designing a system for SAE autonomy level 3 or higher is redundancy. As the influence of the driver is attenuated, it is necessary for the brake system to have the ability to have a failback mode that allows full or near full performance. This typically means a “two-box” approach to the solution. Two basic approaches are known in the industry: one is shown in US 2020 / 0047731 Al, which describes a system consisting of an electro-hydraulic intensifier with an additional stability control system. The other approach is a “one-box” arrangement, adding a separate pump and motor assembly, with the necessary ABS valves and other control valves to complete the system. SUMMARY

[0006] The present disclosure provides an electro-hydraulic brake system for actuating wheel brakes of a vehicle. The electro-hydraulic brake system includes a master cylinder (MC) fluidly coupled to a first MC fluid passageway and configured to supply fluid into the first MC fluid passageway in response to a pressing force on a brake pedal coupled to the MC. The first MC fluid passageway is directly coupled to a pedal feel emulator (PFE) including a PFE piston movable through a PFE bore and separating an upper chamber from a lower chamber to provide a pressure opposite the pressing force on the brake pedal. The electro-hydraulic brake system further includes a pressure supply unit (PSU) assembly including a PSU motor coupled to a ball screw actuator, a PSU housing defining a piston bore having opposite ends from the PSU motor, and a PSU piston disposed within the piston bore and movable by the ball screw actuator through the piston bore and separating the piston bore into a first chamber and a second chamber, each of the first and second chambers containing hydraulic fluid. The electro-hydraulic brake system further includes a backup pump assembly including a backup pump motor operably coupled to a pump to deliver brake fluid to supply the brake fluid to at least one of the wheel brakes. The ball screw actuator includes an actuator nut assembly having a plurality of ball bearings, each of the plurality of ball bearings disposed within the piston bore and immersed in the hydraulic fluid.

[0007] The present disclosure also provides an electro-hydraulic brake assembly. The electro-hydraulic brake assembly includes a hydraulic control unit (HCU) body defining a pressure supply bore, a master cylinder bore, and a backup pump bore; a master piston slidably disposed in the master cylinder bore and configured to supply brake fluid to wheel brakes in response to a pressing of a brake pedal. The electro-hydraulic brake assembly further includes a pressure supply unit including a pressure supply piston disposed within the pressure supply bore, and a PSU motor having a motor shaft configured to linearly translate the pressure supply piston through the pressure supply bore. The electro-hydraulic brake assembly further includes a backup pump assembly including a backup pump motor and a backup pump element disposed in the backup pump bore, the backup pump motor operably coupled to the backup pump element to deliver brake fluid to supply the brake fluid to the wheel brakes. BRIEF DESCRIPTION OF DRAWINGS

[0008] Further details, features, and advantages of the design of the present invention are derived from the following description of exemplary embodiments with reference to the associated drawings.

[0009] Figure 1A schematic block diagram of a brake-by-wire (BbW) system in a vehicle is shown;

[0010] Figure 2 A schematic diagram of a dual-tank BbW system of the present disclosure is shown;

[0011] Figure 3 A perspective view of Figure 2 a dual-tank BbW system of the present disclosure is shown;

[0012] Figure 4 A schematic diagram of an integrated BbW system of the present disclosure is shown;

[0013] Figure 4A A schematic diagram of an alternative integrated BbW system of the present disclosure is shown;

[0014] Figure 5 A schematic diagram of Figure 4 an integrated BbW system of the present disclosure is shown;

[0015] Figure 6 A cross-sectional view of a pressure supply unit (PSU) according to one aspect of the present disclosure is shown;

[0016] Figure 7 A detailed portion of a cross-section of an integrated BbW module of the present disclosure is shown;

[0017] Figure 8 A perspective view of an integrated BbW module of the present disclosure is shown; and

[0018] Figure 9 A perspective view of an integrated BbW module is shown, partially sectioned to show internal details of the ECU. DETAILED DESCRIPTION

[0019] The present application will be described in detail with reference to the following embodiments in conjunction with the accompanying drawings.

[0020] The integrated brake-by-wire system of the present disclosure having a pressure balanced PSU and a wet ball screw combines the pump and motor into a single block. The integrated brake-by-wire system of the present disclosure having a pressure balanced PSU and a wet ball screw can be suitable for Level 3 or higher automation based on SAE International’s “Levels of Automation for Automated Driving” standard, which defines six levels of driving automation as specified in SAE Standard J3016. Furthermore, to avoid redundancy of separate electronic control units (ECUs), the system of the present disclosure can include two isolated circuit boards to meet fail-safe mode safety requirements. This integrated approach can provide lower total cost and reduced installation time in a vehicle.

[0021] Figure 1A schematic block diagram of a brake-by-wire (BbW) system 10 in a vehicle, such as an automobile, is shown. The basic brake-by-wire (BBW) architecture is now widely used in the automotive industry. The master cylinder 12 of the vehicle either directly applies the brakes in a fail-safe mode or is isolated from the wheel brake units 13 and connected to a pedal feel simulator 14 that replicates the force, travel, and damping of a traditional brake system. The BbW system 10 uses the brake pedal travel and / or force and / or brake pressure as input signals to a brake electronic control unit (ECU) 17, which in turn sends appropriate signals to a pressure supply unit (PSU) 16 to apply the corresponding hydraulic brake pressure. The PSU 16 can include a high-efficiency brushless motor and ball screw assembly that displaces one or two pistons, which can be considered an electric master cylinder. The master cylinder 12 and / or the PSU 16 can be coupled to the wheel brake units 13 via a series of control valves 15, which can include apply and release valves (not shown) for each wheel brake unit 13 to provide functions such as anti-lock braking (ABS), electronic traction control, etc.

[0022] The brake pedal input defines the driver intent, which determines the speed and force at which the brakes are applied with the goal of replicating the feel of a conventional vacuum booster brake system and achieving the appropriate vehicle deceleration. The brake ECU 17 can also send signals to a drive control unit (DCU) 18, which can also be referred to as a powertrain control module (PCM), to use one or more electric motors to decelerate the vehicle in a regenerative mode.

[0023] Figure 2 A schematic diagram of a dual-tank BbW system 20 in an electric vehicle for controlling the brake operation of wheel brake units 22a, 22b, 22c, 22d is shown. The wheel brake units 22a, 22b, 22c, 22d can be braked by friction braking from hydraulic application of calipers and brake pads, or they can be braked by regenerative braking torque generated by a motor M coupled to the wheel. The dual-tank BbW system 20 includes a booster unit 30 and a stability control unit 32. There are a total of 18 solenoid-controlled valves in the dual-tank BbW system 120. For redundancy in the event of a PSU failure, the stability control unit 32 can provide a boost output to the wheel brake units 22a, 22b, 22c, 22d by energizing the prime and isolation valves and a backup pump motor 72.

[0024] The twin tank BbW system 20 includes a fluid reservoir 24 that holds and supplies hydraulic fluid to the master cylinder 40. A level sensor 25, such as a float switch, monitors the level of hydraulic fluid in the fluid reservoir 24. A local reservoir 26 is physically attached to the master cylinder 40 and is remote from the fluid reservoir 24. Optionally, a single fluid reservoir 24 can be directly attached to the master cylinder 40, space available in the vehicle. The brake pedal 36 is coupled to press on a brake link 38, which in turn actuates the master cylinder (MC) 40 to pressurize the (MC) fluid passages 34 and 34a of the master cylinder. Travel sensors 37 and 37A each monitor the position of the brake pedal 36.

[0025] A pedal feel emulator (PFE) 42 is fluidly coupled to the MC fluid passage 34 to selectively provide a pressure opposite to the press-on force on the brake pedal 36 to create a natural feel of brake operation, particularly when the master cylinder 40 is decoupled from operation of the wheel brake units 22a, 22b, 22c, 22d. The PFE 42 includes a PFE piston that divides the PFE 42 into an upper chamber and a lower chamber, and a spring that biases the PFE piston into the upper chamber. The upper chamber of the PFE 42 is fluidly coupled to the MC fluid passage 34. The lower chamber of the PFE 42 can be vented to atmosphere.

[0026] A pressure supply unit (PSU) assembly 50 includes a PSU motor 52 and a PSU pump 54 to supply hydraulic fluid from the fluid reservoir 24 to a PSU fluid passage 60. A PFE isolation valve 61, which can be a normally closed solenoid valve, selectively controls fluid flow between the MC fluid passage 34 and the PFE 42. A valve pack 62, which includes four solenoid valves, controls fluid communication between the master cylinder 40 and the brake circuit, and between the PSU assembly 50 and the brake circuit. Thus, the valve pack 62 can control the mode of operation by selectively controlling the source of fluid from either the master cylinder 40 or the PSU assembly 50.

[0027] First and second conduits 74 and 76 provide fluid communication between the booster unit 30 and the stability control unit 32, and correspond to respective ones of the two brake circuits.

[0028] Figure 2Details of the stability control unit 32 are also shown, which includes a set of first ABS valves 80a and a set of second ABS valves 82b, each of which controls fluid flow to a respective one of the wheel brakes 22a, 22b, 22c, 22d. The stability control unit 32 also includes a backup pump assembly 70, which includes a backup pump motor 72 for actuating one or more of the wheel brakes 22a, 22b, 22c, 22d.

[0029] Figure 3 A perspective view of the dual-tank BbW system 20 of Figure 2 is shown. Figure 3 A booster unit 30 is shown connected to the stability control unit 32 by pipes 74, 76. Figure 3 The booster unit 30 is shown, which includes a booster block 94, which can include a block of material (such as metal) that houses various fluid passages and valves. A booster ECU 90 is attached to a side of the booster block 94 for controlling the various valves and the PSU motor 52. Figure 3 The PSU motor 52 is also shown attached to a side of the booster block 94 opposite the side to which the booster ECU 90 is attached and perpendicular to the axis of the master cylinder 40.

[0030] Figure 3 The stability control unit 32 is also shown, which includes a stability control block 96, which can include a block of material (such as metal) that houses various fluid passages and valves. The stability control unit 32 also includes a stability control ECU 92 attached to a side of the stability control block 96 for controlling the various valves and the backup pump motor 72. Figure 3 The backup pump motor 72 is also shown attached to a side of the stability control block 96 opposite the side to which the stability control ECU 92 is attached. The configuration of the second valve set 62b can be shown in US 6,533,369 and / or US 2020 / 0047731. The second dual-tank BbW system 120 includes 17 actuating valves.

[0031] Figure 4A schematic diagram is shown that illustrates details of the integrated BbW system 220. The integrated BbW system 220 is configured as a single monolithic module and includes a fluid reservoir 224 that holds hydraulic fluid and supplies the hydraulic fluid to a master cylinder 230 via an inlet fluid passage 232. The master cylinder 230 is a single circuit device with one piston that linearly displaces through a bore to pump fluid into a master cylinder (MC) fluid passage 234. A fluid level sensor 225, such as a float switch, monitors the level of hydraulic fluid in the fluid reservoir 224. The brake pedal 36 is coupled to press a brake link 38 that in turn actuates the master cylinder 230 to push fluid from the inlet fluid passage 232 through the master cylinder 230 and pressurize the MC fluid passage 234. Travel sensors 37 and 37A monitor the position of the brake pedal 36.

[0032] A pedal feel emulator (PFE) 236 is fluidly coupled to the MC fluid passage 234 to selectively provide a natural feel of brake operation, particularly when the master cylinder 230 is decoupled from operating the wheel brake portions 22a, 22b, 22c, 22d. The PFE 236 includes a PFE piston that divides the PFE 236 into an upper chamber and a lower chamber, and a spring that biases the PFE piston into the upper chamber. The upper chamber of the PFE 236 is fluidly coupled to the MC fluid passage 234. A first pressure sensor 238 monitors the pressure in the MC fluid passage 234. The first pressure sensor 238 can also monitor the temperature in the MC fluid passage 234. The first pressure sensor 238 can also be referred to as a PFE pressure / temperature sensor (PPFE).

[0033] A pressure supply unit (PSU) assembly 240 includes a PSU motor 242 and a PSU pump 244 to supply hydraulic fluid from the fluid reservoir 224 to a PSU fluid passage 250. The PSU assembly 240 can draw fluid from a return fluid passage 252 that is connected to the fluid reservoir 224 and is held at or near ambient atmospheric pressure. A second pressure sensor 251 monitors the pressure in the PSU fluid passage 250. The second pressure sensor 251 can also measure the temperature in the PSU fluid passage. The second pressure sensor 251 can also be referred to as a PSU pressure sensor (PPSU). A rotor angle sensor (RAS) 243 can be coupled to the PSU motor 242 to determine the position of the rotor in the motor and, therefore, the position of the PSU pump 44. The PSU pump 244 includes a PSU piston 245 that separates a first fluid chamber 246 from a second fluid chamber 248.

[0034] The first fluid chamber 246 of the PSU 420 is directly connected to the PSU fluid passage 250. In response to the PSU piston 245 moving away from the PSU motor 242, fluid is pressed out of the first fluid chamber 246 and into the PSU fluid passage 250. The second fluid chamber 248 of the PSU assembly 240 is directly connected to the supplemental fluid passage 254. A check valve 258 allows fluid to flow from the supplemental fluid passage 254 into the PSU fluid passage 250 while preventing fluid flow in the opposite direction. The check valve 258 can also be referred to as a PSU refill check valve (PRCV).

[0035] A PSU reservoir isolation valve (PRIV) 262, which can be a normally closed solenoid valve, selectively controls fluid flow between the return fluid passage 252 and a first intermediate fluid passage 264.

[0036] A displacement fluid passage 268 is connected to the lower chamber of the PFE 236 for transmitting fluid from the lower chamber of the PFE 236 in response to the PFE piston moving due to application of the brake pedal 36. A PFE isolation valve (PFIV) 269, which can be a normally open solenoid valve, selectively couples the intermediate fluid passage 64 and the displacement fluid passage 68.

[0037] A backup pump assembly (BPA) 270 includes a backup pump motor 272 operably coupled to two backup pump elements 274, each configured to deliver brake fluid from the fluid reservoir 224 via the inlet fluid passageway 232 and to the PSU fluid passage 250.

[0038] A master cylinder isolation valve (MCIV) 280, which can be a normally open solenoid valve, selectively controls fluid flow between the MC fluid passage 234 and a second intermediate fluid passage 281. Accordingly, the MCIV 280 can selectively prevent fluid communication between the outlet of the master cylinder 230 and the wheel brake portions 22a, 22b, 22c, 22d. A second pressure / temperature sensor 282, which can be referred to as a pressure master cylinder (PMC) sensor, monitors pressure and / or pressure in the second intermediate fluid passage 281. A secondary source valve (SSV) 284, which can be a normally open solenoid valve, selectively controls fluid flow between the second intermediate fluid passage 281 and the PSU fluid passage 250. Accordingly, the SSV 284 can control flow of brake fluid between the outlet of the master cylinder 230 and the wheel brake portions 22a, 22b, 22c, 22d to define a proportion of flow by which the system operates in a fail-safe mode. A secondary source bypass valve (SSVB) 286, which can be a normally closed solenoid valve, selectively controls fluid flow between the second intermediate fluid passage 281 and the inlet of the BPA 270.

[0039] A fourth check valve 288 is connected between the inlet fluid passage 232 and the inlet of the BPA 270 and is configured to allow fluid to flow from the inlet fluid passage 232 into the inlet of the BPA 270 while preventing fluid flow in the opposite direction. The fourth check valve 288 can also be referred to as a backup reservoir check valve (BRCV).

[0040] The PSU fluid passage 250 divides the fluid supply into a first brake circuit 290 and a second brake circuit 292. In some embodiments, and as shown, the first brake circuit 290 is connected to the front wheel brake portions 22a, 22b, and the second brake circuit 292 is connected to the rear wheel brake portions 22c, 22d. However, other configurations can be used. Figure 4

[0041] The control valve manifold 300 fluidly connects the two brake circuits 290, 292 to the corresponding wheel brake portions 22a, 22b, 22c, 22d. The control valve manifold 300 includes apply valves 302a, 302b, 302c, 302d and release valves 304a, 304b, 304c, 304d corresponding to each of the wheel brake portions 22a, 22b, 22c, 22d to selectively control fluid flow between the corresponding one of the wheel brake portions 22a, 22b, 22c, 22d and the associated one of the two brake circuits 290, 292. The apply valves 302a, 302b, 302c, 302d and release valves 304a, 304b, 304c, 304d can be collectively referred to as anti-lock braking system (ABS) valves for their use in such ABS. However, the apply valves 302a, 302b, 302c, 302d and release valves 304a, 304b, 304c, 304d can be used for other functions, such as for traction control and / or for torque vectoring.

[0042] ​A first isolation valve 306, which may be a normally open solenoid valve, is configured to selectively control fluid flow in the first brake circuit 290 between the PSU fluid passage 250 and the control valve manifold 300. The first isolation valve 306 may also be referred to as a front isolation valve (FIV). A second isolation valve 308, which may be a normally open solenoid valve, is configured to selectively control fluid flow in the second brake circuit 292 between the PSU fluid passage 250 and the control valve manifold 300. The second isolation valve 306 may also be referred to as a rear isolation valve (RIV). One or both of the first isolation valve 306 and / or the second isolation valve 308 can be used to prevent pressure medium (i.e., brake fluid) from flowing from the wheel brake sections 22a, 22b, 22c, 22d to the fluid reservoir 224 in an inactive state. When the application valves 302a, 302b, 302c, 302d are closed, the first isolation valve 306 and / or the second isolation valve 308 can control the outflow in an active state, thereby causing a reduction in wheel brake pressure.

[0043] In some implementations, and as such Figure 4 As shown, two-way check valves 310 and 311 are provided in each of the two brake circuits 290 and 292 between the PSU fluid passage 250 and the control valve manifold 300. Each of the two-way check valves 310 and 311 allows fluid to flow in either direction, but only when the pressure difference across it exceeds a certain threshold. The two-way check valves 310 and 311 can limit the amount of fluid lost in the event of system leakage (such as leakage in the brake lines supplying any one of the wheel brake units 22a, 22b, 22c, 22d).

[0044] Figure 4An integrated BbW system 220 is also shown, which includes a brake system electronic control unit (ECU) 340 with electrical connections for monitoring various sensors 37, 37A, 225, 238, 243, 251, 282 and for controlling various actuators such as the PSU motor 242, the backup pump motor 272, the EPB actuator 346, and various solenoid valves 262, 269, 280, 284, 286, 302a, 302b, 302c, 302d, 304a, 304b, 304c, 304d, 306, 308. The ECU 340 is also connected to one or more external controllers 342 of the vehicle via a communication network such as a controller area network (CAN bus). These external controllers 342 can control features such as autonomous driving, steering sensors, and warning lights. ECU 340 includes a first printed circuit board (PCB) 210 and a second PCB 212 configured to provide independent control loops. The first PCB 210 includes a first control loop that provides power and / or control signals to the PSU motor 242 to control its operation. The second PCB 212 includes a second control loop that provides power and / or control signals to a standby pump motor 272 to control its operation. In some embodiments, the first PCB 210 provides normal automatic braking, while the second PCB 212 provides redundant automatic braking in failover mode due to a failure of the first PCB 210 or any associated equipment (e.g., a failure or malfunction of the PSU component 240). In some embodiments, an electrically isolated communication network, such as a Controller Area Network (CAN), can provide communication between the first PCB 210 and the second PCB 212.

[0045] In some implementations, and as such Figure 4 As shown, ECU 340 can be connected to an electric parking brake (EPB) switch 344 to activate EPB actuators 346 on one or more of the wheel brakes 22a, 22b, 22c, and 22d, such as the right rear wheel brake 22c and the left rear wheel brake 22d. However, the other wheel brakes among the wheel brakes 22a, 22b, 22c, and 22d may include EPB actuators 346.

[0046] Figure 4A It shows the relationship with Figure 4 The integrated BbW system 220 shown is almost identical to the alternative integrated BbW system 520. The alternative integrated BbW system 520 provides an enhanced failover mode that exceeds the requirements for meeting SAE Level 3. Figure 4A The BbW system in Figure 4The BbW system shown in the middle is identical except for the following three changes: 1) the pump reserve reservoir check valve BRCV 288 is removed, 2) a pedal feel failure backup valve (PFFV) 501 is added, and 3) a master cylinder failure backup valve (MCFV) 502 is added. The PFFV 501 selectively controls fluid flow between the inlet fluid passage 232 and the displacement fluid passage 268. Although other types of valves can be used, the PFFV 501 can be a normally open solenoid valve. The MCFV 502 selectively controls fluid flow between the third intermediate fluid passage 503 and the second intermediate fluid passage 281. Although other types of valves can also be used, the MCFV 502 can be a normally open solenoid valve. The MCIV 280 is fluidly connected to the third intermediate fluid passage 503 and selectively controls fluid flow between the MC fluid passage 234 and the third intermediate fluid passage 503. Thus, either the MCFV 502 or the MCIV 280 can selectively prevent fluid communication between the outlet of the master cylinder 230 and the wheel brakes 22a, 22b, 22c, 22d. The MCFV 502 and the MCIV 280 can each be controlled by different control circuits. For example, the MCIV 280 can be controlled by the control circuit of the first PCB 210, while the MCFV 502 can be controlled by the control circuit of the second PCB 212. Further, the second pressure / temperature sensor 282 can monitor pressure and / or pressure in the third intermediate fluid passage 503.

[0047] Both the PFFV 501 and the MCFV 502 are powered by the second PCB 212, which is configured to provide full braking functionality in the event of a failure of the PSU assembly 240 and / or the first circuit board 210 or otherwise unavailable. If the failure backup mode is needed, then the PFFV 501 and the MCFV 502 are activated to provide the full braking functionality. Figure 4As with the integrated BbW system 220 in FIG. 2, the backup pump motor 272 of the BPA 270 will run when increased pressure is needed. All valves are in their normal state except for the SSV 284, the SSBV 286, the PFFV 501, and the MCFV 502. The SSBV 286 is energized to open the pump bypass recirculation loop. The SSV 284 is a linear normally open valve that can control the amount of fluid that flows through it based on the amount of current applied. If no current is applied, the SSV 284 is fully open and creates very little back pressure, and fluid is only recirculated through the SSBV. If full current is applied, the SSV 284 is fully closed, and all flow goes to the wheel brakes 22a, 22b, 22c, 22d. Thus, by controlling the current to the SSV 284 proportionally to the master cylinder stroke, a proportional brake pressure is created that significantly reduces the effort of the driver to slow the vehicle. Once the desired pressure is reached, the SSV 284 can be fully applied to close the valve, and the backup pump motor can be turned off to conserve current consumption. The PFFV 501 and the MCFV 502 are both energized. This keeps the master cylinder 230 isolated from the wheel brakes and allows the pedal feel simulator 236 to function. Thus, the driver’s pedal feel is still very similar to the pedal feel in normal BbW mode, which will be more comfortable for the driver.

[0048] Figure 5 A schematic diagram of the integrated BbW system 220 of the present disclosure is shown. Figure 5 How the various electrical components of the integrated BbW system 220 are controlled by one of two independent control networks, in the form of first printed circuit board (PCB) 210 and second PCB 212, each of which has a separate power supply and separate electrical ground connection, is shown.

[0049] The integrated BbW system 220 of the present disclosure is capable of meeting Level 3+ safety requirements. The integrated BbW system 220 includes the following features: the first PCB 210 can operate the integrated BbW system 220 in a normal operating mode, and the second PCB 212 can operate the integrated BbW system 220 in a fail-safe mode. The fail-safe mode can be used to operate the wheel brake units 22a, 22b, 22c, 22d in the event that the normal operating mode is unavailable. For example, in the event of a mechanical or electrical component failure of the first PCB 210 or one or more devices connected thereto. The second PCB 212 can be configured to utilize a control valve to control a backup pump and motor assembly to provide pressure for operating the wheel brake units 22a, 22b, 22c, 22d in the event that the PSU assembly 240 is unable to provide pressure for operating the wheel brake units 22a, 22b, 22c, 22d.

[0050] Figure 6 A cross-sectional view of the PSU assembly 240 of the integrated BbW system 220 is shown. The PSU assembly 240 includes a PSU motor 242 configured to operate a PSU pump 244 to discharge brake fluid to a PSU fluid passage 250.

[0051] The PSU assembly 240 includes a PSU housing 360 that defines a piston bore 362. The PSU housing 360 also defines a back chamber 364 that houses the PSU motor 242. A bulkhead 366 separates the piston bore 362 from the back chamber 364. The bulkhead 366 allows the back chamber 364 to remain dry while the piston bore 362 contains brake fluid. The PSU motor 242 includes a motor shaft 370 coupled to a set of arc-shaped permanent magnets 372 that are acted upon by electrical current in a stator 374. Shaft bearings 376 can support the motor shaft 370 on either side of the magnets 372.

[0052] The PSU pump 244 includes a PSU piston 245 acted upon by an actuator nut 380. An outer surface of the actuator nut 380 is permanently connected to the PSU piston 245. The PSU piston 245 is rotationally limited but free to translate by a rotation prevention feature 396, for example, a series of protrusions or bumps that fit onto a corresponding rotation prevention feature 398, such as a series of slots, keyways, or troughs in the PSU housing 360, on their outer diameter. The PSU motor 242 rotates a spindle 382 that is threaded and configured to move the actuator nut 380 in a linear path, thereby translating the PSU piston 245 in either direction toward or away from the PSU motor 242 through the piston bore 362.

[0053] In some embodiments, one or more ball bearings 384 can be disposed between the spindle 382 and the actuator nut 380, providing a ball screw interface. A gear set 386, which can include one or more planetary reduction gears, mechanically couples the motor shaft 370 of the PSU motor 242 and the spindle 382, thereby reducing the speed applied to the spindle 322 and increasing the torque applied to the spindle 382. A high pressure rotary seal 378 is disposed about the spindle 322 at the bulkhead 366, thereby providing a fluid seal between the piston bore 362 and the back chamber 364 while allowing the spindle 382 to rotate. The high pressure rotary seal 378 can include a lip seal. However, other types of seals can be used.

[0054] The PSU piston 245 is disposed within the piston bore 362 and is configured to move linearly through the piston bore 362 in response to being pushed and / or pulled by the actuator nut 380. The piston bore 362 extends between the bulkhead 366 and the tip 388. The piston bore 362 defines a first fluid chamber 246 that extends from the PSU piston 245 to the tip 388. The piston bore 362 also defines a second fluid chamber 248 that extends from the bulkhead 366 to the PSU piston 245. A first PSU port 390 provides fluid communication between the first fluid chamber 246 and an external fluid circuit. The first PSU port 390 can be fluidly coupled to the PSU fluid passage 250 for supplying fluid to the PSU fluid passage 250. A second PSU port 392 provides fluid communication between the second fluid chamber 248 and the external fluid circuit. The second PSU port 392 can be fluidly coupled to the replenishment fluid passage 254 for delivering fluid between the second fluid chamber 248 and the replenishment fluid passage 254.

[0055] In some embodiments, as shown in FIG. 4, the PSU piston 245 includes a PSU piston seal 394, such as a lip seal, that prevents the PSU piston 245 from leaking fluid between the first fluid chamber 246 and the second fluid chamber 248. Figure 6

[0056] The high pressure rotary seal 378 can serve multiple functions. First, the high pressure rotary seal 378 can allow the PSU assembly 240 to be regenerated at system pressure. Additionally, in the event of a failure of the PSU piston seal 394, the high pressure rotary seal 378 will prevent fluid from entering the PSU motor 242 and thus maintain the integrity of the hydraulic system. This can be particularly important for providing back-up for a single circuit master cylinder.

[0057] ​The actuator nut 380, spindle 382, and one or more ball bearings 384 can be collectively referred to as a ball screw mechanism 380, 382, 384. A unique feature of the PSU assembly 240 of the present disclosure is how the ball screw mechanism 380, 382, 384 is sealed on the spindle 382, eliminating the need for a separate push rod actuator. The result is that the ball screw mechanism 380, 382, 384 nests within the PSU piston 245 and is flooded with brake fluid for lubrication. Another benefit of this design is that a simple straight bore can be used for the PSU piston 245 since the fluid displacement on both sides of the PSU piston seal 394 is identical. Finally, the high pressure rotary seal 378 provides a secondary leak barrier to maintain system integrity in the event of a PSU piston seal 394 failure.

[0058] Referring to Figure 4 The integrated BbW system 220 of the present disclosure can be referred to as a 15 valve design because it includes fifteen actuated valves 262, 269, 280, 284, 286, 302a, 302b, 302c, 302d, 304a, 304b, 304c, 304d, 306, 308. However, aspects of the integrated BbW system 220 of the present disclosure can be implemented in systems with a different number of actuated valves.

[0059] When in normal, line control braking mode and the driver applies the brake pedal, the MCIV 280 is closed and the PRIV 262 is open. The master cylinder fluid is directed to the PFE 236 to simulate normal brake pedal force and travel. This same travel information is sent to the ECU 340 which then applies the appropriate current to the PSU motor 242 to rotate the ball screw and mechanically displace the PSU piston 245. This causes the fluid to travel through the dual check valve 310, through the ABS apply valves 302a, 302b, 302c, 302d and finally to the wheel brakes 22a, 22b, 22c, 22d to apply pressure and slow the vehicle down.

[0060] Since this is an "open" system, meaning that the fluid released from the wheel brakes 22a, 22b, 22c, 22d when the ABS stops is not captured, but instead flows back to the fluid reservoir 224 under atmospheric pressure, it is necessary to replenish the PSU assembly 240. This is accomplished by first closing the PRIV 262 and the PFIV 269, which captures the pressure behind the PSU piston 245. The front isolation valve (FIV) 306 and the rear isolation valve (RIV) 308 are also closed to lock the system pressure at the wheel brakes 22a, 22b, 22c, 22d. The ball screw and the PSU piston 245 retract. This forces the fluid behind the PSU piston 245 to flow to the front of the PSU piston 245 via the second check valve 258. The pressures on both sides of the PSU piston 245 are maintained during the replenishment, as both sides of the PSU piston 245 displace equal volumes as the PSU piston 245 travels. When the PSU piston 245 begins to advance again, the PRIV 262, the PFIV 269, the FIV 306, and the RIV 308 all return to their previous states.

[0061] To meet the requirements for driving automation level 3, the autonomous driving system must monitor itself and have a redundant path to continue driving the vehicle. Likewise, the brake system must include redundancy to execute commands from the autonomous driving system, such as advanced driver assistance systems (ADAS), to be able to slow and stop the vehicle after any first failure of the brake system. Therefore, the integrated BbW system 220 of the present disclosure can include a redundant power supply to the wheel brakes and a redundant control network with separate power supplies to be able to stop the vehicle under all conditions.

[0062] If the PSU assembly 240 fails, the BPA 270 can open immediately whenever the driver applies the brakes. At the same time, the PRIV 262 will be de-energized and remain closed, and the MCIV 280 will be de-energized and remain open. The SSBV 286 will be energized to allow pump recirculation, and the SSV 284, which can be a linear valve, will be driven and actuated proportionally to brake pedal travel according to feedback from the second pressure sensor 251 to ensure that the relationship between the driver's intent to slow down and the pedal force is satisfied. In some embodiments, the SSV 284 can be a current-controlled valve, controlled by the amount of current supplied to it.

[0063] If the autonomous driving mode, such as ADAS control, is required and there is no driver assistance, the only difference is that the SSBV 286 is closed, and the pump recirculation fluid now returns through a bypass hole in the master cylinder 230 when the driver is not depressing the brake pedal. The system pressure is determined by the current applied to the SSV 284.

[0064] Figure 7A detailed portion of a cross-section of an integrated BbW module 400 including the integrated BbW system 220 of the present disclosure is shown. The integrated BbW module 400 includes a hydraulic control unit (HCU) block 402, which can be a metal block such as aluminum. The HCU block 402 can be machined or otherwise formed to define various fluid passages and other structural and functional components. As shown, Figure 7 The HCU block 402 includes a plurality of faces arranged at right angles, including a top face 403, one or more side faces 404 extending parallel to and spaced apart from each other, and two end faces 406 extending parallel to and spaced apart from each other and perpendicular to the side faces 404. Each of the side faces 404 and end faces 406 can be vertical when installed in a vehicle. The fluid reservoir 224 can be located on the top face 403 of the HCU block 402.

[0065] The integrated BbW module 400 also includes a PSU sleeve 408 located on one of the side faces 404 and housing one or more components of the PSU assembly 240. The integrated BbW module 400 also includes an HCU motor housing 410 containing the PSU motor 242 and / or other components of the PSU assembly 240, such as the gear set 386. Together, the HCU block 402, the PSU sleeve 408, and / or the HCU motor housing 410 can form the PSU housing 360. Figure 7 The placement of the ECU 340 in the ECU housing 341 relative to the HCU block 402 is also shown. In some embodiments, the ECU housing 341 can be directly against the HCU block 402.

[0066] The integrated BbW module 400 contains a transverse motor configuration. In the transverse motor configuration, the HCU block 402 includes the master cylinder 40, 230 and the PSU assembly 240, with the PSU motor 242 mounted transverse to the master cylinder 40, 230. In some embodiments, and as shown, Figure 7 The PSU motor 242 is mounted on a side face 404 of the HCU block 402, and the master cylinder 40, 230 is defined in an end face and extends into the HCU block 402 transverse to the end face. In other words, the PSU motor 242 is mounted with its motor shaft 370 extending horizontally and perpendicular to the master cylinder 40, 230. For example, the HCU block 402 can define a master cylinder bore (not shown in the figures) configured to house a master cylinder piston of the master cylinder 40, 230, and perpendicular to the motor shaft 370 of the PSU motor 242.

[0067] Such an arrangement is possible due to the compact nature of the PSU assembly 240 of the present disclosure. The PSU motor 242 can include a standard brushless motor, and the gear set 386 can include a planetary gear set. Such a configuration can minimize total cost, maximize motor efficiency, and minimize motor current consumption, thereby saving electronics capital.

[0068] Figure 8 A perspective view of the integrated BbW module 400 is shown, including the PSU motor 242 and the backup pump motor 272, each located on the same side face 404 of the HCU block 402 and adjacent to one another. The HCU block 402 can define a backup pump bore (not shown, but located near the backup pump motor 272) in which one or more backup pump elements 274 are disposed.

[0069] Figure 9 A perspective view of the integrated BbW module 400 is shown, with a partial cutaway to show internal details of the ECU 340. Figure 8 An ECU housing 341 is shown that includes two PCBs 210, 212, each extending parallel to one another and spaced apart from one another. The two PCBs 210, 212 of the ECU 340 can also be parallel to the side face 404 of the HCU block 402.

[0070] Figure 8 And Figure 9 A packaging design is shown that places the PSU motor 242 and the backup pump motor 272 on the same face as the ECU 340, opposite one another. By allowing both hydraulic power units to directly interface with the ECU 340, this layout can minimize cost compared to alternative arrangements, reducing the number of interconnections.

[0071] The integrated BbW system 220 and associated integrated BbW module 400 of the present disclosure are configured to meet backup redundancy requirements for automation class 3 and above. The integrated BbW system 220 and associated integrated BbW module 400 of the present disclosure are configured to provide backup redundancy in the event of a failure of the pressure supply unit assembly 240 and are packaged as a single assembly. The integrated BbW system 220 and associated integrated BbW module 400 of the present disclosure include: 1) an integrated backup pump assembly (i.e., BPA 270), and 2) two independent printed circuit boards within a single electronic control unit housing 341.

[0072] The first printed circuit board 210 can control the normally lined brake components including the PSU assembly 240. The second printed circuit board 212, which can be independent of the first printed circuit board 210, will have the ability to continue to drive the vehicle and to execute commands from external sources, such as ADAS, in order to slow and stop the vehicle even in the event of a failure of the first printed circuit board 210.

[0073] This unique combination of design, including a pressure balanced PSU piston 245 with a rotating lip seal on the main shaft and a transverse motor layout with integrated planetary gear set, makes it a truly unique design.

[0074] According to one aspect of the present disclosure, the brake system of a motor vehicle in a normally lined brake operation mode can be activated by a driver or an autonomous driving device to slow the vehicle, and the same brake system in a fail-safe mode with a failed pressure supply unit can be normally activated by the driver in a fully boosted mode.

[0075] SUMMARY

[0076] The present disclosure provides an electro-hydraulic brake system for actuating wheel brakes of a vehicle. The electro-hydraulic brake system includes a master cylinder (MC) fluidly coupled to a first MC fluid passage and configured to supply fluid into the first MC fluid passage in response to a pressing force on a brake pedal coupled to the master cylinder. The first MC fluid passage is directly coupled to a pedal feel simulator (PFE) including a PFE piston movable through a PFE bore and separating an upper chamber from a lower chamber to provide a pressure opposite to the pressing force on the brake pedal. The electro-hydraulic brake system further includes a pressure supply unit (PSU) assembly including a PSU motor coupled to a ball screw actuator, a PSU housing defining a piston bore having opposite ends from the PSU motor, and a PSU piston disposed within the piston bore and movable by the ball screw actuator through the piston bore and separating the piston bore into a first chamber and a second chamber, each of the first and second chambers containing hydraulic fluid. The electro-hydraulic brake system further includes a backup pump assembly including a backup pump motor operably coupled to a pump to deliver brake fluid to supply the brake fluid to at least one of the wheel brakes. The ball screw actuator includes an actuator nut assembly having a plurality of ball bearings, each of the plurality of ball bearings disposed within the piston bore and immersed in the hydraulic fluid.

[0077] In some embodiments, the master cylinder is a single circuit master cylinder having a single piston and defining a single pressure chamber connected to the wheel brake portion.

[0078] In some embodiments, the electro-hydraulic brake system further comprises an electronic control unit (ECU) including a first control circuit configured to power the PSU motor, and a second control circuit independent of the first control circuit and configured to power the backup pump motor.

[0079] In some embodiments, the ECU further comprises a first printed circuit board (PCB) defining the first control circuit; the ECU further comprises a second PCB isolated from the first PCB and defining the second control circuit; and an electrically isolated communication network provides communication between the first PCB and the second PCB.

[0080] In some embodiments, the electro-hydraulic brake system further comprises a travel sensor configured to monitor a position of the brake pedal.

[0081] In some embodiments, the electro-hydraulic brake system further comprises an incoming fluid passage configured to transfer brake fluid between a fluid reservoir and the master cylinder, a displacement fluid passage connected to the lower chamber of the PFE, and a pedal feel failure backup valve (PFFV) configured to selectively prevent fluid communication between the incoming fluid passage and the displacement fluid passage.

[0082] In some embodiments, the PFFV is a normally open solenoid valve.

[0083] In some embodiments, the electro-hydraulic brake system further comprises a master cylinder isolation valve (MCIV) configured to selectively prevent fluid communication between an outlet of the master cylinder and the wheel brake portion.

[0084] In some embodiments, the MCIV is a normally open solenoid valve.

[0085] In some embodiments, the electro-hydraulic brake system further comprises: an electronic control unit (ECU) comprising a first control circuit configured to power the PSU motor, and a second control circuit independent of the first control circuit and configured to power the backup pump motor; a master cylinder failure backup valve (MCFV) fluidly connected in series with the MCIV, the MCFV configured to selectively prevent fluid communication between an outlet of the master cylinder and the wheel brake portion. In some embodiments, the MCIV and the MCFV are controlled by different ones of the first control circuit and the second control circuit, respectively.

[0086] In some embodiments, the MCFV is a normally open solenoid valve.

[0087] In some embodiments, the electro-hydraulic brake system further comprises a secondary source valve (SSV) configured to control flow of brake fluid between an outlet of the master cylinder and the wheel brake portion.

[0088] In some embodiments, the SSV is a normally open linear valve that can variably control flow through the normally open linear valve.

[0089] In some embodiments, the electro-hydraulic brake system further comprises: a PSU fluid passage configured to transmit fluid from the pressure supply unit assembly to the wheel brake portion; a control valve manifold comprising at least one of an apply valve and a release valve for controlling fluid flow between the PSU fluid passage and at least one of the wheel brake portions; and an isolation valve configured to selectively control fluid flow between the PSU fluid passage and the control valve manifold.

[0090] In some embodiments, the electro-hydraulic brake system further comprises: a PSU fluid passage configured to transmit fluid from the PSU assembly to at least one wheel brake portion; a control valve manifold comprising at least one of an apply valve and a release valve for controlling fluid flow between the PSU fluid passage and the at least one wheel brake portion; a bidirectional check valve disposed between the PSU fluid passage and the control valve manifold and configured to allow fluid flow between the pressure supply unit fluid passage and the control valve manifold in either of two opposite directions only when a pressure differential across the bidirectional check valve is greater than a predetermined amount.

[0091] In some embodiments, the electro-hydraulic brake system further comprises a PSU fluid passage configured to transmit fluid from the PSU assembly to at least one wheel brake; a control valve manifold comprising at least one of an apply valve and a release valve for controlling fluid flow between the PSU fluid passage and the at least one wheel brake; and an isolation valve disposed between the PSU fluid passage and the control valve manifold and configured to selectively control fluid flow between the pressure supply unit fluid passage and the control valve manifold.

[0092] The present disclosure also provides an electro-hydraulic brake assembly comprising a hydraulic control unit (HCU) body defining a pressure supply bore, a master cylinder bore, and a backup pump bore; a master piston slidably disposed in the master cylinder bore and configured to supply brake fluid to a wheel brake in response to depression of a brake pedal. The electro-hydraulic brake assembly further comprises a pressure supply unit comprising a pressure supply piston disposed within the pressure supply bore, and a PSU motor having a motor shaft configured to linearly translate the pressure supply piston through the pressure supply bore. The electro-hydraulic brake assembly further comprises a backup pump assembly comprising a backup pump motor and a backup pump element disposed in the backup pump bore, the backup pump motor operably coupled to the backup pump element to deliver brake fluid to supply brake fluid to the wheel brake.

[0093] In some embodiments, the HCU body comprises a top face, two side faces extending parallel to and spaced apart from each other, and an end face extending perpendicular to the top face and each of the two side faces. In some embodiments, the master cylinder bore is defined in the end face. In some embodiments, the PSU motor and the backup pump motor are both located on a same one of the two side faces of the HCU body.

[0094] In some embodiments, the electro-hydraulic brake assembly further comprises a fluid reservoir disposed on the top face of the HCU body.

[0095] In some embodiments, the electro-hydraulic brake assembly further comprises an electronic control unit (ECU) coupled to a side of the HCU body opposite the PSU motor and the backup pump motor.

[0096] In some embodiments, the brake system includes inlet valves and outlet valves for each wheel brake unit for setting wheel individual brake pressure originating from signals generated by an electronic control unit, wherein the inlet valves in a deactivated state transmit fluid to the wheel brake units and in an activated state limit or prevent build-up of wheel pressure and build-up of wheel pressure in the outlet valves. The inlet valves can include apply valves 302a, 302b, 302c, 302d and the outlet valves can include release valves 304a, 304b, 304c, 304d.

[0097] In some embodiments, the brake system includes a single HCU block 402 that houses at least a portion of each of the pressure supply unit assembly 240 and the backup pump assembly 270, wherein the two associated motor assemblies are located on a single face of the HCU block 402 opposite the face that houses the control valves and sensors; the reservoir is located on a top face perpendicular to the face of the PSU; and the master cylinder bore is perpendicular to the PSU bore.

[0098] The foregoing description is not intended to be exhaustive or to limit the disclosure to the precise embodiments disclosed. Various elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable with other embodiments, as applicable, and can be used in selected embodiments even if not specifically shown or described. Various elements or features of specific embodiments can be changed or modified without departing from the disclosure. Such changes or modifications are intended to be included within the scope of the disclosure and are to be covered by the following claims.

[0099] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 287,047, filed December 7, 2021, the contents of which are incorporated by reference in their entirety.

Claims

1. An electro-hydraulic brake system for actuating wheel brakes of a vehicle, the electro-hydraulic brake system comprising: a master cylinder fluidly coupled to a first master cylinder fluid passage and configured to supply fluid into the first master cylinder fluid passage in response to a press force on a brake pedal coupled to the master cylinder; the first master cylinder fluid passage directly coupled to a pedal feel simulator, the pedal feel simulator including a pedal feel simulator piston movable through a pedal feel simulator bore and separating an upper chamber from a lower chamber to provide a pressure opposing the press force on the brake pedal; a pressure supply unit assembly including a pressure supply unit motor coupled to a ball screw actuator, a pressure supply unit housing defining a piston bore having distal ends opposing the pressure supply unit motor, and a pressure supply unit piston disposed within the piston bore and movable by the ball screw actuator through the piston bore and separating the piston bore into a first chamber and a second chamber, each of the first and second chambers containing hydraulic fluid; a backup pump assembly including a backup pump motor operably coupled to a pump to deliver brake fluid to supply the brake fluid to at least one of the wheel brakes; and wherein the ball screw actuator includes an actuator nut assembly having a plurality of ball bearings, each of the plurality of ball bearings disposed within the piston bore and immersed in the hydraulic fluid, wherein the electro-hydraulic brake system further includes a secondary source valve configured to control flow of brake fluid between an outlet of the master cylinder and the wheel brakes, wherein the secondary source valve is a normally open linear valve variably controllable to flow through the normally open linear valve. the master cylinder is a single circuit master cylinder having a single piston and defining a single pressure chamber connected to the wheel brakes.

2. The electro-hydraulic brake system of claim 1, wherein, 3. The electro-hydraulic brake system of claim 1, further comprising an electronic control unit including a first control circuit configured to supply power to the pressure supply unit motor, and a second control circuit independent of the first control circuit and configured to supply power to the backup pump motor. the electronic control unit further includes a first printed circuit board defining the first control circuit; 4. The electro-hydraulic brake system of claim 3, wherein, wherein the electronic control unit further includes a second printed circuit board isolated from the first printed circuit board and defining the second control circuit; and wherein an electrically isolated communication network provides communication between the first printed circuit board and the second printed circuit board.

5. The electro-hydraulic brake system of claim 1, further comprising a travel sensor configured to monitor a position of the brake pedal. ​ 6. The electro-hydraulic brake system of claim 5, further comprising: an inlet fluid passage configured to transfer brake fluid between a fluid reservoir and the master cylinder; a displacement fluid passage connected to the lower chamber of the pedal feel simulator; and a pedal feel failure backup valve configured to selectively prevent fluid communication between the inlet fluid passage and the displacement fluid passage.

7. The electro-hydraulic brake system of claim 6, wherein, The pedal feel failure backup valve is a normally open solenoid valve.

8. The electro-hydraulic brake system of claim 1, further comprising a master cylinder isolation valve configured to selectively prevent fluid communication between an outlet of the master cylinder and the wheel brake portion.

9. The electro-hydraulic brake system of claim 8, wherein, The master cylinder isolation valve is a normally open solenoid valve.

10. The electro-hydraulic brake system of claim 8, further comprising: an electronic control unit including a first control circuit configured to power the pressure supply unit motor, and a second control circuit independent of the first control circuit and configured to power the backup pump motor; a master cylinder failure backup valve fluidly connected in series with the master cylinder isolation valve and configured to selectively prevent fluid communication between the outlet of the master cylinder and the wheel brake portion; and wherein the master cylinder isolation valve and the master cylinder failure backup valve are controlled by different ones of the first control circuit and the second control circuit, respectively.

11. The electro-hydraulic brake system of claim 10, wherein, The master cylinder failure backup valve is a normally open solenoid valve.

12. The electro-hydraulic brake system of claim 1, further comprising: a pressure supply unit fluid passage configured to transfer fluid from the pressure supply unit assembly to the wheel brake portion; a control valve manifold including at least one of an apply valve and a release valve for controlling fluid flow between the pressure supply unit fluid passage and at least one of the wheel brake portions; and an isolation valve configured to selectively control fluid flow between the pressure supply unit fluid passage and the control valve manifold.

13. The electro-hydraulic brake system of claim 1, further comprising: a pressure supply unit fluid passage configured to transfer fluid from the pressure supply unit assembly to at least one wheel brake portion; a control valve manifold including at least one of an apply valve and a release valve for controlling fluid flow between the pressure supply unit fluid passage and the at least one wheel brake portion; a bidirectional check valve disposed between the pressure supply unit fluid passage and the control valve manifold and configured to allow fluid flow in either of two opposite directions between the pressure supply unit fluid passage and the control valve manifold only when a pressure differential across the bidirectional check valve is greater than a predetermined amount.

14. The electro-hydraulic brake system of claim 1, further comprising: a pressure supply unit fluid passage configured to transmit fluid from the pressure supply unit assembly to at least one wheel brake; a control valve manifold including at least one of an apply valve and a release valve for controlling fluid flow between the pressure supply unit fluid passage and the at least one wheel brake; and an isolation valve disposed between the pressure supply unit fluid passage and the control valve manifold and configured to selectively control fluid flow between the pressure supply unit fluid passage and the control valve manifold.

15. An electro-hydraulic brake assembly comprising: a hydraulic control unit body defining a pressure supply bore, a master cylinder bore, and a backup pump bore; a master piston of a master cylinder slidably disposed in the master cylinder bore and configured to supply brake fluid to a wheel brake in response to depression of a brake pedal; a pressure supply unit including a pressure supply piston disposed within the pressure supply bore and a pressure supply unit motor having a motor shaft configured to linearly translate the pressure supply piston through the pressure supply bore; and a backup pump assembly including a backup pump motor and a backup pump element disposed in the backup pump bore, the backup pump motor operably coupled to the backup pump element to deliver brake fluid to supply the brake fluid to the wheel brake, wherein the electro-hydraulic brake assembly further comprises a secondary source valve configured to control flow of brake fluid between an outlet of the master cylinder and the wheel brake, wherein the secondary source valve is a normally open linear valve that is variably controllable to control flow through the normally open linear valve. the hydraulic control unit body includes a top face, two side faces extending parallel to and spaced apart from each other, and an end face extending perpendicular to the top face and each of the two side faces; 16. The electro-hydraulic brake assembly of claim 15, wherein, wherein the master cylinder bore is defined in the end face; and wherein the pressure supply unit motor and the backup pump motor are both located on a same one of the two side faces of the hydraulic control unit body.

17. The electro-hydraulic brake assembly of claim 16, further comprising a fluid reservoir disposed on the top face of the hydraulic control unit body.

18. The electro-hydraulic brake assembly of claim 16, further comprising an electronic control unit coupled to a side face of the hydraulic control unit body opposite the pressure supply unit motor and the backup pump motor. ​

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