Brake system having electric motor-driven master cylinder and electric secondary power transmission unit

Abstract

The invention relates to a brake system having an electric motor driven master cylinder and an electric secondary power transmission unit. A brake system for actuating a plurality of wheel brakes including a first pair of wheel brakes and a second pair of wheel brakes includes a reservoir and a motor-driven master cylinder operable during a normal non-fail braking mode to generate brake actuation pressure at a first MC output and a second MC output, and a hydraulic actuator for hydraulically actuating the first pair of wheel brakes and the second pair of wheel brakes. The secondary power transmission unit is configured to selectively provide pressurized hydraulic fluid at the first PTU output and the second PTU output, and includes a PTU motor configured to selectively pressurize the hydraulic fluid by transmitting rotational motion to the at least two pump pistons. The secondary power transfer unit is indirectly fluidly connected to the reservoir to selectively draw hydraulic fluid from the reservoir.

Description

Technical Field

[0001] The present disclosure relates to an apparatus and method for a brake system using a master cylinder and a secondary power transfer unit driven by an electric motor, and more particularly to a method and apparatus for a brake system, wherein the electric secondary power transfer unit is indirectly fluidly connected to a reservoir for fluid replenishment. Background Art

[0002] The braking system may include an anti-lock control including a hydraulic brake pressure generator, a brake pressure regulator, a sensor and an electronic circuit, the brake pressure regulator 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 a hydraulic fluid, the sensor being used to determine the wheel rotation behavior, the electronic circuit being used to process the sensor signal and being used to generate a brake pressure control signal. The braking system may also include both an anti-lock control and a traction slip control, the traction slip control being able to use the brake pressure regulator to control vehicle braking.

[0003] Descriptions of prior art braking systems are provided in U.S. Patent No. 10,730,501, issued to Blaise Ganzel on August 4, 2020, and entitled “Vehicle Braking System with Auxiliary Pressure Source,” U.S. Patent Application Publication No. 2020 / 0307538, published on October 1, 2020 by Blaise Ganzel, and entitled “Braking System with Multiple Pressure Sources,” and U.S. Patent Application No. 17 / 400,250, 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

[0004] In one aspect, a braking system for actuating a plurality of wheel brakes including a first pair of wheel brakes and a second pair of wheel brakes is disclosed. The braking system includes a reservoir and a motor-driven master cylinder, which can be operated to generate a brake actuation pressure at a first MC output and a second MC output by actuation of a motor of the master cylinder during a normal non-fault braking mode for hydraulically actuating the first pair of wheel brakes and the second pair of wheel brakes. A secondary power transfer unit is configured to selectively provide pressurized hydraulic fluid at a first PTU output and a second PTU output for actuating the first pair of wheel brakes and the second pair of wheel brakes in at least one of a normal non-fault braking mode and a backup braking mode. The secondary power transfer unit includes a PTU motor configured to selectively pressurize the hydraulic fluid by transmitting a rotational motion to at least two pump pistons. Each pump piston provides pressurized hydraulic fluid to a corresponding one of the first PTU output and the second PTU output. Each of the first PTU output and the second PTU output provides fluid to a corresponding pair of wheel brakes in the first pair of wheel brakes and the second pair of wheel brakes. An electronic control unit is provided for controlling at least one of the power transfer unit and the master cylinder. The auxiliary power transfer unit is indirectly fluidly connected to the reservoir to selectively draw hydraulic fluid from the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] For a better understanding, reference may be made to the accompanying drawings, in which:

[0006] Figure 1 is a schematic hydraulic diagram of an exemplary braking system according to an aspect of the present invention; and

[0007] Figure 2 yes Figure 1 Schematic hydraulic diagram of an exemplary braking system in an alternative configuration. DETAILED DESCRIPTION

[0008] Unless defined otherwise, 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.

[0009] The present invention comprises, consists of, or consists essentially of any combination of the following features.

[0010] Figure 1An exemplary braking system 100 for actuating a plurality of wheel brakes 102 is schematically shown. The braking system 100 is shown here as a hydraulic braking system, wherein a braking force is applied to the braking system 100 using fluid pressure. The braking system 100 can be suitably used on a ground vehicle, such as a motor vehicle having four wheels, wherein a wheel brake is associated with each wheel. In addition, the braking system 100 may be provided with other braking functions, such as anti-lock braking (ABS) and other slip control features, to effectively brake the vehicle. The components of the braking system 100 may be housed in one or more blocks or housings. The blocks or housings may be made of a solid material, such as aluminum, which has been drilled, machined or otherwise formed to accommodate various components. Fluid conduits may also be formed in the blocks or housings.

[0011] exist Figure 2 In the embodiment of the braking system 100 shown, there are four wheel brakes 102, each of which may have any suitable wheel brake structure that is electrically operated and / or operated by applying a pressurized brake fluid. Each wheel brake 102 may include, for example, 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 102 may be associated with any combination of the front wheels and rear wheels of the vehicle on which the corresponding braking system 100 is installed. For example, the braking system 100 may be configured as a system that is vertically separated or diagonally separated. Although a person of ordinary skill in the art can easily provide a suitable braking device for a specific use environment, for the purpose of this specification, no distinction is made between the wheel brakes 102. For the purpose of description, two pairs of wheel brakes 102 are shown in the figure as being separated on the right and left sides of the included schematic diagram, without considering the actual position of these wheel brakes 102 on the corresponding vehicle. The right pair of wheel brakes 102 (in the orientation of the figure) will be referred to as the “first” pair of wheel brakes 102 and the left pair of wheel brakes 102 (in the orientation of the figure) will be referred to as the “second” pair of wheel brakes 102 .

[0012] Also for purposes of description, it is assumed that a deceleration signal transmitter (schematically shown at 104) is configured to provide a braking signal corresponding to a desired braking action of a vehicle operator in a wired or wireless manner. The deceleration signal transmitter 104 may include, but is not limited to, a brake pedal, an autonomous braking controller, and / or any other suitable scheme for generating a braking signal according to which the braking system 100 may be actuated.

[0013] The brake system 100 also includes a fluid reservoir 106. The reservoir 106 stores and holds hydraulic fluid for the brake system 100. The fluid in the reservoir 106 is preferably maintained at atmospheric pressure or approximately atmospheric pressure, but the fluid can be stored at other pressures if desired. The reservoir 106 is schematically shown as having two tanks or parts, which are connected to fluid lines. These parts can be separated by several inner walls within the reservoir 106, and are provided to prevent the complete discharge of the reservoir 106 in the event that one of these parts is exhausted due to a leak in one of the lines connected to the reservoir 106. Any number of lines can be connected to the reservoir 106, and a person of ordinary skill in the art can easily provide a reservoir 106 of appropriate construction for a specific use environment. Alternatively, the reservoir 106 may include a plurality of separate housings. The reservoir 106 may include at least one fluid level sensor 108 for detecting the fluid level of one or more of these parts of the reservoir 106.

[0014] The braking system 100 includes a motor-driven master cylinder 110 that serves as a pressure source to provide a desired pressure level to a hydraulically operated wheel brake 102 during a typical or normal non-fault braking application. The motor-driven master cylinder ("MC") 110 shown in the figure is a dual-chamber type master cylinder. An example of a suitable MC 110 arrangement is disclosed in co-pending U.S. patent application No. 17 / 708,070, which was filed on March 30, 2022 and is entitled "Tandem Power Transfer Unit and Braking System Using the Same" (Attorney Docket No. 211835-US-NP), the entire contents of which are incorporated herein by reference for all purposes.

[0015] The MC 110 includes a ball screw 112, a ball nut 114 selectively driven by the ball screw 112 to move longitudinally relative to the ball screw, and a main piston 116 operatively coupled to the ball nut 114 (e.g., via a press-fit connection therebetween). The main piston 116 is indirectly driven by the ball screw 112 to reciprocate longitudinally via engagement of the main piston 116 with the ball nut 114. The term "longitudinal" as used herein refers to the longitudinal direction of the main piston 116. Figure 1 to Figure 2 The orientation of is substantially horizontal and is indicated by arrow “Lo”. Attached to the primary piston 116 is a slave piston 118 , which is also indirectly driven by the ball screw 112 via motion transmitted through the primary piston 116 .

[0016] The block housing (shown schematically at 120) at least partially surrounds the primary piston 116, the secondary piston 118, and the ball screw 112. The primary chamber 122 is at least partially defined by the block housing 120 and the surfaces of the primary piston 116. The secondary chamber 124 is at least partially defined by the surfaces of the block housing 120 and the secondary piston 118. The primary chamber 122 and the secondary chamber 124 are each configured to contain a hydraulic fluid and to be selectively pressurized by the reciprocating longitudinal movement of the primary piston 116 and the secondary piston 118 relative to the block housing 120.

[0017] An electric motor 126 is provided for selectively driving the ball screw 112 to responsively reciprocate the primary piston 116 and the secondary piston 118 within the primary chamber 122 and the secondary chamber 124. The MC 110 is operable in a normal, non-fault braking mode to generate brake actuation pressures at a first MC output 128 and a second MC output 130 by actuation of the electric motor 126 of the MC 110 for hydraulically actuating the first pair of wheel brakes 102 and the second pair of wheel brakes 102, respectively. A spring 132 may be provided in the primary chamber 122 to bias the secondary piston 118 to the left in the orientation of the figure, thereby facilitating desired operation of the MC 110 and / or the larger brake system 100.

[0018] Reference Figure 1 Each of the main chamber 122 and the secondary chamber 124 may include at least one annular seal groove configured to accommodate any desired type of annular seal 134 for preventing hydraulic fluid from flowing out of the corresponding main chamber 122 or the secondary chamber 124 in an undesired direction. For example, a V-shaped seal may be disposed at the rightmost position (at the bottom) of at least one of the main chamber 122 and the secondary chamber 124. Figure 1 The W-shaped seal or cup-shaped seal may be disposed in a seal groove further to the left (in the direction of Figure 1 The sealing groove is arranged in a cavity upward to provide the required sealing performance in a specific use environment.

[0019] The master piston 116 and the slave piston 118 may also each include at least one piston port 136 that selectively connects the corresponding master chamber 122 or slave chamber 124 to the reservoir 106 fluid via the first reservoir line 138 and the second reservoir line 140, respectively. Once the master piston 116 and the slave piston 118 reciprocate past the depicted seal 134 (e.g., to the left of the leftmost seal in each corresponding master chamber 122 or slave chamber 124), the piston port 136 "closes" and blocks fluid communication between the chamber and the reservoir 106.

[0020] After the brakes are applied, fluid from the wheel brakes 102 may be returned to the motor-driven master cylinder 110 and / or diverted to the reservoir 106. It is also contemplated that other configurations (not shown) of the brake system 100 may include hydraulic control of only a selected one or more of the wheel brakes 102 (the others being electrically controlled / electrically actuated). Following further aspects of the present invention, one of ordinary skill in the art will be readily able to provide such an arrangement for the desired use environment.

[0021] The braking system 100 includes a secondary power transfer unit ("PTU") 142 for selectively providing pressurized hydraulic fluid at a first PTU output 144 and a second PTU output 146, respectively, for actuating a corresponding first pair of wheel brakes 102 and a second pair of wheel brakes 102 in at least one of a normal non-fault braking mode and a backup braking mode. That is, each of the first PTU output 144 and the second PTU output 146 provides fluid to a corresponding pair of wheel brakes in the first pair of wheel brakes 102 and the second pair of wheel brakes 102.

[0022] The slave PTU 142 includes a PTU motor 148 configured to selectively pressurize hydraulic fluid by transmitting rotational motion to at least two pump pistons 150 and 152, respectively. Each pump piston 150 and 152 provides pressurized hydraulic fluid to a corresponding one of the first PTU output 144 and the second PTU output 146. In the figures, each pump piston 150 and 152 is associated with two wheel brakes 102, for a total of two pump pistons 150 and 152 in the brake system 100. However, it is contemplated that any desired number of pump pistons may be provided to the slave PTU 142, such as a plurality of pump pistons associated with at least one of the first PTU output 144 and the second PTU output 146. In many use environments, it may be desirable to have an even number of master pump pistons to facilitate balance in the mechanism of the slave PTU 142.

[0023] The slave PTU 142 of the braking system 100 may be used as a pressure source to provide a desired pressure level to selected wheel brakes 102 in a backup or "failure" condition (in a backup or "failure" condition, the motor-driven MC 110 is unable to provide fluid to those selected wheel brakes 102 for some reason). The slave PTU 142 may be used in this backup braking mode, but may also selectively provide hydraulic fluid to at least one of the wheel brakes 102 in an enhanced braking mode, which may occur independently and / or simultaneously with the backup braking mode or non-failure normal braking mode. Examples of suitable enhanced braking mode functions that may be used for the braking system 100 include, but are not limited to, "overboost" (wherein a higher pressure than is normally available from the PTU 100 alone is provided to a particular brake) and "volume-add" (wherein more fluid than is normally available from the PTU 100 is provided to a particular brake). As another example, the slave PTU 142 may be used to selectively provide hydraulic fluid to at least one of the wheel brakes 102 in an enhanced braking mode. 142 is operable to provide pressurized hydraulic fluid to at least one of the first pair of wheel brakes 102 and the second pair of wheel brakes 102 under slip control conditions of a normal non-fault braking mode. A person of ordinary skill in the art can readily configure the braking system 100 with the desired interaction and mode for a particular use environment of the present invention.

[0024] The brake system 100 also includes at least one electronic control unit ("ECU") 154 for controlling at least one of the secondary PTU 142 and the motor-driven MC 110, wherein a first ECU 154A and a second ECU 154B are shown and described herein. The ECUs 154A, 154B may include a microprocessor and other circuits. The ECUs 154A, 154B receive various signals, process the signals, and control the operation of various electrical components of the corresponding brake system 100 in a wired and / or wireless manner in response to the received signals. For example, the ECUs 154A and / or 154B may control at least one of the power transfer unit 142 and the master cylinder 110 in response to the brake signal generated by the deceleration signal transmitter 104.

[0025] The ECU 154A, 154B may be connected to various sensors, such as a reservoir fluid level sensor 108, a pressure sensor, a travel sensor, a switch, a wheel speed sensor, and a steering angle sensor. The ECU 154A, 154B 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 various reasons (such as, but not limited to, controlling the braking system 100 during vehicle braking, stability operation, or other operating modes). In addition, the ECU 154A, 154B may be connected to an instrument cluster for collecting and providing information related to warning indicators, such as an ABS warning light, a brake fluid level warning light, and a traction control / vehicle stability control indicator light. It is contemplated that at least one of the ECUs 154A and 154B may be integrated into at least one of the motor-driven MC 110 or the secondary PTU 142, for example.

[0026] When there are two ECUs provided to the brake system 100, the first ECU 154A is operable to control the motor 126 of the motor-driven MC 110 and to control any desired one or more of the valves of the brake system 100, as will be discussed below. The second ECU 154B is operable to control the PTU motor 148 and to control any desired one or more of the valves of the brake system 100, as will be discussed below.

[0027] An example of a suitable ECU 154 device is disclosed in co-pending U.S. patent application Ser. No. 17 / 708,019 (Attorney Docket No. 211652-US-NP-2, hereinafter referred to as “backup ECU”), entitled “CONTROL DEVICE FOR BRAKING SYSTEM,” filed concurrently with the present application, the entire contents of which are incorporated herein by reference for all purposes.

[0028] An isolation / pressure reducing control valve device is associated with each wheel brake 102 of the plurality of wheel brakes 102. Each isolation / pressure reducing control valve device includes an isolation valve 156 and a pressure reducing valve 158 for providing a desired fluid route to the associated wheel brake 102. Each isolation / pressure reducing control valve device is controlled by at least one selected ECU of the first ECU 154A and the second ECU 154B, or by a single ECU when only one ECU is present. For some use environments of the brake system 100, it may be desirable to control the isolation / pressure reducing control valve device by the same ECU of the first ECU 154A and the second ECU 154B that controls the motor-driven MC 110 to control the wheel brake 102 during a normal, non-fault braking mode.

[0029] The reservoir 106 is hydraulically connected to the motor-driven MC 110 and each isolation / relief control valve device, for example, via a return line 160. For a corresponding wheel brake 102, a normally open isolation valve 156 for each isolation / relief control valve device is hydraulically located between the corresponding wheel brake 102 and the motor-driven MC 110, and a normally closed relief valve 158 for each isolation / relief control valve device is hydraulically located between the corresponding wheel brake 102 and the reservoir 106. Each isolation / relief control valve device is in fluid communication with a selected one of the first MC output 128 and the second MC output 130 and a selected one of the first PTU output 144 and the second PTU output 146 for selectively receiving pressurized hydraulic fluid therefrom.

[0030] The isolation / relief control valve arrangement may selectively provide slip control to at least one wheel brake 102 powered by the motor-driven MC 110 and / or slave PTU 142. More generally, the isolation / relief control valve arrangement and / or other valves of the braking system 100 (any of which may be solenoid-operated and of any suitable configuration) may be used to help provide controlled braking operations such as, but not limited to, ABS, traction control, vehicle stability control, dynamic rear ratio modulation, regenerative brake blending, and autonomous braking.

[0031] The first traction control isolation valve 162 and the second traction control isolation valve 164 are each hydraulically interposed between the motor-driven MC 110 and the at least one wheel brake 102. For example, and as shown, the first traction control isolation valve 162 and the second traction control isolation valve 164 may each be hydraulically interposed between the motor-driven MC 110 and the at least one isolation / relief control valve arrangement via the first MC output 128 and the second MC output 130, respectively. The first traction control isolation valve 162 and the second traction control isolation valve 164 operate to help direct hydraulic fluid to the isolation / relief control valve arrangement as needed.

[0032] Each of the first traction control isolation valve 162 and the second traction control isolation valve 164 is controlled by at least a selected one of the first ECU 154A and the second ECU 154B, or by a single ECU when only one ECU is present. For some use environments of the braking system 100, it may be desirable that the first traction control isolation valve 162 and the second traction control isolation valve 164 be controlled by the same ECU of the first ECU 154A and the second ECU 154B that controls the motor-driven MC 110 for controlling the wheel brakes 102 during the normal non-fault braking mode.

[0033] In short, Figure 1 to Figure 2In the illustrated braking system 100, when the braking system 100 is in a normal non-fault braking mode, at least the first ECU 154A is operable to control the motor 126 of the motor-driven MC 110, the isolation / pressure reducing control valve arrangement (including the isolation valve 156 and the pressure reducing valve 158), and at least one of the first traction control isolation valve 162 and the second traction control isolation valve 164. Similarly, at least when the braking system 100 is in a backup braking mode, and optionally, as previously described, when the braking system 100 is in a normal non-fault braking mode, at least the second ECU 154B is operable to control the PTU motor 148 having the pump piston 150 to achieve a desired braking response.

[0034] At least one pressure sensor 166 (three are shown) may be provided to sense the pressure of the pressurized hydraulic fluid at one or both of the first MC output 128 and the second MC output 130. The one or more pressure sensors 166 may be positioned in direct hydraulic connection with the motor-driven MC 110 and / or in indirect hydraulic connection with the respective first MC output 128 or second MC output 130, such as by being positioned downstream of the first traction control isolation valve 162 or the second traction control isolation valve 164. When the pressure sensor 166 is present, it operates to provide a pressure signal to at least one of the ECUs 154A and 154B in response to the sensed pressure. (For example, at least one pressure sensor 166 associated with the motor-driven MC 110 may be monitored by one ECU 154A or 154B, and at least one pressure sensor 166 associated with the PTU motor 148 may be monitored by another ECU 154B or 154A.) One of ordinary skill in the art may readily configure the brake system 100 to have the desired number / arrangement / type of pressure sensors for a particular use environment.

[0035] In the brake system 100 shown and described herein, the pump pistons 150, 152 of the slave PTU 142 are indirectly fluidly / hydraulically connected to the reservoir 106 to selectively draw hydraulic fluid from the reservoir 106. For example, Figure 1As shown in the braking system 100 of FIG. 1 , each of the first MC output 128 and the second MC output 130 is in fluid communication with a pump input of at least one pump piston 150, 152 for selectively supplying pressurized hydraulic fluid thereto. In at least one of the normal non-fault braking mode and the backup braking mode, the slave PTU 142 selectively boosts the pressure of the pressurized hydraulic fluid to supply the boosted pressure hydraulic fluid to at least one of the first PTU output 144 and the second PTU output 146. For example, during certain stages of normal non-fault braking mode operation, the motor-driven MC 110 may not be able to operate to provide a desired amount and / or pressure of pressurized hydraulic fluid to one or more wheel brakes 102; in such a case, the slave PTU 142 would be used to supplement the motor-driven MC 110. As another example, when the braking system 100 is in a backup braking mode because the motor-driven MC 110 is unavailable for various reasons, the slave PTU 142 will replace the motor-driven MC 110 and provide a predetermined amount of pressurized hydraulic fluid to one or more wheel brakes 102 to replace the fluid that the affected wheel brakes 102 would normally receive from the motor-driven MC 110.

[0036] like Figure 1 As shown, an indirect connection between the slave PTU 142 (ie, its pump pistons 150, 152) and the reservoir 106 is formed by at least one check valve 168 hydraulically interposed therebetween. Figure 1 In the arrangement of FIG. 1 , for a total of two check valves 168 as shown, a different check valve 168 is hydraulically interposed between the reservoir 106 and each of the pump pistons 150 , 152 , but any desired number of check valves 168 may be provided for a particular use environment of the brake system 100 . Figure 1 In the illustrated brake system 100 , when the pressure in the corresponding pump piston 150 , 152 is high enough to overcome the biasing force of the check valve 168 , each check valve 168 will open to allow hydraulic fluid from the reservoir 106 to pass therethrough and “suck” fluid from the reservoir 106 to maintain a desired amount of fluid in and downstream of the corresponding pump piston 150 , 152 .

[0037] In short, if Figure 1As shown in the braking system 100 of FIG. 1 , the slave PTU 142 can selectively draw hydraulic fluid from the reservoir 106 through at least one check valve 168 to supplement (and may include completely replace) the pressurized hydraulic fluid from the motor-driven MC 110. As a result, even if one of the ECUs 154A, 154B is unavailable for the braking system 100 for some reason, the fluid level in the reservoir 106 can be monitored and adjusted by controlling the motor 126 or the PTU motor 148, depending on which of the ECUs 154A, 154B is still available in the braking system 100 at that time.

[0038] In other words, and if Figure 1 As shown, each pump piston 150, 152 has two associated wheel brakes 102, and an isolation / relief control valve arrangement that provides pressurized hydraulic fluid to two associated wheel brakes 102 on the same side of the brake system 100; as shown, there are a total of two pump pistons 150, 152 in the brake system 100. In the brake system 100, boost braking can be provided using a PTU motor 148 acting through two pump pistons 150, 152, because the pump pistons 150, 152 can draw fluid indirectly from the reservoir 106 via the check valve 168 and do not rely entirely on fluid from the motor-driven MC 110 to operate.

[0039] Figure 2 A second embodiment of a brake system 100 ′ is shown. Figure 2 The brake system 100' is similar to Figure 1 The braking system 100 is therefore similar to the reference Figure 1 Those structures described are the same or similar Figure 2 The structures have the same reference numerals and are marked with "superscript symbols". For the second embodiment, the description of common elements and operations similar to those in the aforementioned first embodiment will not be repeated, but should be considered appropriately incorporated by reference below.

[0040] like Figure 2 As shown, the slave PTU 142' can selectively draw hydraulic fluid from the reservoir 106' (indirectly) via the motor-driven MC 110'. Figure 2 In the illustrated braking system 100', when the pressure in the corresponding pump piston 150', 152' is low enough to overcome the internal biasing forces of the various components of the motor-driven MC 110', the passages within the motor-driven MC 110' can open to allow hydraulic fluid from the reservoir 106' to pass therethrough and thereby "suck" fluid from the reservoir 106' to maintain a desired amount of fluid in and downstream of the corresponding pump piston 150', 152'.

[0041] To facilitate the desired opening of the fluid passage through the structure of the motor-driven MC 110', the motor-driven MC 110' may include at least one return spring 270 that biases open the supplemental fluid path between the secondary PTU 142' and the reservoir 106' (e.g., through the leftmost piston port 136') in response to de-energization of the motor-driven MC 110'. When the return spring 270 is present, the PTU motor 148' does not need to work hard enough to overcome the lip seal rupture pressure and other forces within the primary chamber 122' and / or the secondary chamber 124' to open the supplemental fluid path. Due to the presence of the return spring 270, the PTU motor 148' can be smaller, lighter, and less expensive than a PTU motor that may be required without the "biasing assistance" from the return spring 270, and / or the return spring 270 can avoid the presence of one or more check valves or other valves (not shown) that may otherwise be required to provide the desired braking system characteristics.

[0042] In short, if Figure 2 As shown in the braking system 100', the slave PTU 142' can selectively draw hydraulic fluid from the reservoir 106' through a replenishment fluid path extending through the motor-driven MC 110' to replenish (which may include fully replenishing) pressurized hydraulic fluid from the motor-driven MC 110'.

[0043] All of the isolation valves 156, the pressure reducing valve 158, the first traction control isolation valve 162 and the second traction control isolation valve 164 are shown as Figure 1 to Figure 2 The brake system 100, 100' of the present invention is single-wound and can include dual / redundant electronic control circuits as needed. In other implementations of the brake system 100, 100', it is considered to also use dual-wound valves or use dual-wound valves instead. When dual-wound valves and / or motors 126 and 148 are present, the ECU 154A, 154B can control any one or more of these dual-wound valves and motors in the first (normal) and / or second (backup) braking modes.

[0044] It is contemplated that the PTU 110 may be located remotely from one or more other components of the brake system 100, as may be desired for space, manufacturing, and / or any other reasons for a particular use environment of the brake system 100. Conversely, the PTU 110 may be co-located with other components of the brake system 100; one of ordinary skill in the art may readily provide a suitably configured brake system 100 as desired.

[0045] It is contemplated that a person skilled in the art may provide various other components, such as service and / or parking brake motors, in any brake system described herein to achieve a desired configuration for a particular use environment. For example, although a plurality of filters and pressure sensors are shown in the accompanying drawings, a detailed description thereof is omitted herein for the sake of brevity, as a person skilled in the art will readily understand how to provide the desired number, arrangement and / or operation of filters, sensors and any other components according to the needs of the particular use environment of the present invention.

[0046] 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 terms "include" and / or "comprise" used herein may specify the presence of the features, steps, operations, elements, and / or components, but do not exclude the presence or addition of other features, steps, operations, elements, components, and / or combinations thereof.

[0047] As used herein, the term "and / or" may include any and all combinations of one or more of the associated listed items.

[0048] It should be understood that when an element is referred to as being "on another element," "attached to another element," "connected to another element," "coupled with another element," "contacting another element," "adjacent to another element," etc., the element may be directly on, attached to, connected to, coupled with, contacting, or adjacent to another element, or there may be intervening elements. Conversely, when an element is referred to as being, for example, "directly on another element," "directly attached to another element," "directly connected to another element," "directly coupled with another element," "directly contacting another element," or "directly adjacent to another element," there are no intervening elements. One of ordinary skill in the art will also understand that a reference to a structure or feature disposed "directly adjacent to" another feature may have a portion overlapping the adjacent feature or a portion located below the adjacent feature, while a structure or feature disposed "adjacent to" another feature may not have a portion overlapping the adjacent feature or a portion located below the adjacent feature.

[0049] Spatially relative terms, such as "under," "beneath," "lower," "above," "upper," "proximal," "distal," and the like, may be used herein to facilitate description of the relationship of one element or feature to another element or feature as shown in the figures. It should be understood that the spatially relative terms may include different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is inverted, elements described as "under" or "beneath" other elements or features would be oriented "above" the other elements or features.

[0050] 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, the selection of which may change over time. Conversely, the phrase "at least one of X" may be interpreted to include one or more X.

[0051] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements are not 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. The order of operations (or steps) is not limited to the order given in the claims or drawings unless otherwise specifically noted.

[0052] Although aspects of the present disclosure have been specifically shown and described with reference to the exemplary aspects above, it will be understood by those skilled in the art that various additional aspects can be envisioned. For example, the specific methods of using the above-mentioned devices are merely illustrative; those skilled in the art can easily determine any number of tools, sequence of steps, or other ways / options for placing the above-mentioned devices or their components in positions substantially similar to those shown and described herein. In order to maintain clarity in the drawings, certain repeated components are not specifically numbered, but those skilled in the art will recognize the element numbers that should be associated with the unnumbered components based on the numbered components; the presence or absence of element numbers in the drawings does not intend or imply a distinction between similar components. Any of the described structures and components can be integrally formed as a single whole or single piece, or composed of separate sub-components, wherein any of these constructions includes any suitable raw materials or custom components and / or any suitable material or combination of materials. Any of the described structures and components can be disposable or reusable as required by the specific use environment. Any component may have a user-perceivable mark to indicate the material, configuration, at least one dimension, etc. associated with the component, the user-perceivable mark potentially helping the user select a component from an array of similar components for a specific use environment. The "predetermined" state can be determined at any time before the structure being manipulated actually reaches the state, and the "predetermining" is performed shortly before the structure reaches the predetermined state. The term "substantially" is used herein to indicate a specified quality to a large extent (but not necessarily all)-the "substantially" quality allows for the possibility of some relatively small inclusion of non-quality items. 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 characteristics desired 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 would be 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 incorporating any of these features should be understood to fall within the scope of the present disclosure determined based on the following claims and any equivalents thereof.

[0053] Other aspects, objects and advantages can be obtained from a study of the drawings, the disclosure and the appended claims.

[0054] Related Applications

[0055] This application is related to the technology disclosed in one or more of the following: U.S. Provisional Patent Application (Application Number Pending) (Attorney Docket No. 300063-US-PSP [3]), which is filed concurrently with the present application and is entitled “PUSH THRUSCA"; U.S. Patent Application No. 18 / 447,490 (Attorney Docket No. 300080-US-NP), which is filed concurrently with the present application and is entitled "Braking System with Master Cylinder and Single Angle Actuator"; U.S. Patent Application No. 18 / 447,566 (Attorney Docket No. 300510-US-NP), which is filed concurrently with the present application and is entitled "Braking System with Motor-Driven Master Cylinder and Wheel-Side Pressure Sensor"; U.S. Patent Application No. 18 / 447,609 (Attorney Docket No. 300642-US-NP), which is filed concurrently with the present application and is entitled "Vent Valve and Braking System Using the Vent Valve"; and U.S. Patent Application (Application Number Pending) (Attorney Docket No. 301149-US-NP), which is filed concurrently with the present application and is entitled "Bleed Valve and Braking System Using the Bleed Valve". The entire contents of all of these applications are incorporated herein by reference.

Claims

1. A braking system for actuating a plurality of wheel brakes including a first pair of wheel brakes and a second pair of wheel brakes, the braking system comprising: Storage; a motor-driven master cylinder operable during a normal, non-fault braking mode by actuation of an electric motor of said master cylinder to generate brake actuation pressures at a first master cylinder output and a second master cylinder output for hydraulically actuating said first pair of wheel brakes and said second pair of wheel brakes, respectively; a secondary power transfer unit configured to selectively provide pressurized hydraulic fluid at a first power transfer unit output and a second power transfer unit output for actuating the first pair of wheel brakes and the second pair of wheel brakes in at least one of a normal non-failure braking mode and a backup braking mode, the secondary power transfer unit including a power transfer unit motor configured to selectively pressurize the hydraulic fluid by transmitting rotational motion to at least two pump pistons, each pump piston providing pressurized hydraulic fluid to a corresponding one of the first power transfer unit output and the second power transfer unit output, each of the first power transfer unit output and the second power transfer unit output providing fluid to a corresponding pair of wheel brakes of the first pair of wheel brakes and the second pair of wheel brakes; as well as an electronic control unit for controlling at least one of the auxiliary power transfer unit and the master cylinder; Wherein, the secondary power transfer unit is indirectly fluidly connected to the reservoir to selectively draw hydraulic fluid from the reservoir.

2. The brake system according to claim 1, comprising an isolation / pressure reducing control valve device associated with each wheel brake of the plurality of wheel brakes, each isolation / pressure reducing control valve device being controlled by the electronic control unit.

3. The braking system according to claim 2, wherein: Each isolation / reducing control valve device is in fluid communication with both a selected one of the first and second master cylinder outputs and a selected one of the first and second power transfer unit outputs for selectively receiving pressurized hydraulic fluid therefrom.

4. The braking system according to claim 1, wherein: The motor-driven master cylinder is a dual-chamber master cylinder.

5. The braking system according to claim 1, wherein: The secondary power transfer unit includes a plurality of pump pistons associated with each of the first power transfer unit output and the second power transfer unit output.

6. The braking system according to claim 1, comprising: a first traction control isolation valve hydraulically interposed between the motor-driven master cylinder and the first pair of wheel brakes via the first master cylinder outlet; as well as A second traction control isolation valve is hydraulically interposed between the motor-driven master cylinder and the second pair of wheel brakes via the second master cylinder outlet.

7. The braking system of claim 6, comprising an isolation / relief control valve arrangement associated with each of the first pair of wheel brakes and the second pair of wheel brakes, wherein: The first traction control isolation valve is hydraulically interposed between the motor-driven master cylinder and the isolation / decompression control valve arrangement of the first pair of wheel brakes, and wherein the second traction control isolation valve is hydraulically interposed between the motor-driven master cylinder and the isolation / decompression control valve arrangement of the second pair of wheel brakes.

8. The braking system according to claim 1, wherein: The electronic control unit is a first electronic control unit that controls the motor-driven master cylinder, and the brake system includes a second electronic control unit that controls the auxiliary power transfer unit.

9. The braking system of claim 8, comprising an isolation / relief control valve arrangement associated with each of the first pair of wheel brakes and the second pair of wheel brakes, wherein: The first electronic control unit controls each of the isolation / pressure reducing control valve devices.

10. The brake system according to claim 1, comprising: a first traction control isolation valve hydraulically interposed between the motor-driven master cylinder and the first pair of wheel brakes via the first master cylinder outlet; as well as a second traction control isolation valve hydraulically interposed between the motor-driven master cylinder and the second pair of wheel brakes via the second master cylinder outlet; The second electronic control unit controls the first traction control isolation valve and the second traction control isolation valve.

11. The braking system of claim 1, comprising a deceleration signal transmitter configured to provide a braking signal corresponding to a desired braking action of an operator of the vehicle in a wired or wireless manner, wherein: The electronic control unit controls at least one of the auxiliary power transfer unit and the motor-driven master cylinder in response to the brake signal.

12. The brake system according to claim 1, wherein: Each of the first master cylinder output end and the second master cylinder output end is fluidically connected to the pump input end of at least one pump piston for selectively supplying pressurized hydraulic fluid to the at least one pump piston. In at least one braking mode of a normal non-fault braking mode and a backup braking mode, the auxiliary power transfer unit selectively boosts the pressure of the pressurized hydraulic fluid to supply hydraulic fluid with boosted pressure to at least one of the first power transfer unit output end and the second power transfer unit output end.

13. The braking system according to claim 12, wherein: The braking system includes at least one check valve hydraulically disposed between the secondary power transfer unit and the reservoir, wherein the secondary power transfer unit selectively draws hydraulic fluid from the reservoir through the at least one check valve to replenish the pressurized hydraulic fluid from the motor-driven master cylinder.

14. The braking system according to claim 12, wherein: The secondary power transfer unit selectively draws hydraulic fluid from the reservoir via the motor-driven master cylinder.

15. The braking system according to claim 14, wherein: The motor-driven master cylinder includes at least one return spring that biases open a replenishment fluid path between the secondary power transfer unit and the reservoir in response to de-energizing the motor-driven master cylinder.

16. The brake system of claim 12, comprising a pressure sensor sensing the pressure of pressurized hydraulic fluid at at least one of the first master cylinder output and the second master cylinder output, the pressure sensor providing a pressure signal to the electronic control unit in response to the sensed pressure.

17. The braking system according to claim 1, wherein: The secondary power transfer unit is operative to provide pressurized hydraulic fluid to at least one of the first pair of wheel brakes and the second pair of wheel brakes under slip control conditions of a normal, non-failure braking mode.

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