TWI837571B - Braking system for a bicycle - Google Patents

Abstract

Example brake systems and apparatus for providing pitch control on bicycles are described herein. An example rear brake caliper described herein includes a caliper housing to be coupled to the bicycle. The caliper housing includes a first port to be fluidly coupled to a first fluid line fluidly coupled to a front brake actuator and a second port to be fluidly coupled to a second fluid line fluidly coupled to a front brake caliper. The rear brake caliper also includes a valve between the first port and the second port. The valve is operable to affect fluid flow between the first port and the second port.

Description

Braking system for bicycles

Invention Field

The present invention relates generally to bicycle brake systems, and more particularly to brake systems and devices for providing bicycle control.

Invention Background

Bicycles and other two-wheeled vehicles often include a front brake and a rear brake. The front brake can be actuated to slow the front wheel, and the rear brake can be actuated to slow the rear wheel. The front and rear brakes are actuated independently by separate levers or actuators. A rider has a relatively high center of gravity on a bicycle. If the rider actuates the front brake to provide a high rate of deceleration, the rear wheel of the bicycle may rise off the ground. This results in less control over the bicycle. Furthermore, in extreme cases, the rise of the rear wheel can cause a rider to tip over the front of the bicycle, which may cause injury to the rider.

Summary of the invention

An exemplary rear brake caliper for a bicycle is disclosed herein. The rear brake caliper includes a caliper housing for coupling to the bicycle. The caliper housing includes a first port and a second port, the first port for fluid coupling to a first fluid circuit fluidly coupled to a front brake actuator, and the second port for fluid coupling to a second fluid circuit fluidly coupled to a front brake caliper. The rear brake caliper also includes a valve between the first port and the second port. The valve is operable to affect fluid flow between the first port and the second port.

An exemplary brake system for a bicycle is disclosed herein. The brake system includes a front brake actuator, a front brake caliper, a rear brake actuator, a rear brake caliper, a first fluid circuit coupled between the front brake actuator and the rear brake caliper, a second fluid circuit coupled between the rear brake caliper and the front brake caliper, and a third fluid circuit coupled between the rear brake actuator and the rear brake caliper. Actuation of the front brake actuator causes the first brake fluid to be supplied to the front brake caliper through the first fluid line, the rear brake caliper, and the second fluid line to actuate the front brake caliper to apply brake pressure to a front wheel of the bicycle. Actuation of the rear brake actuator supplies the second brake fluid to the rear brake caliper to apply brake pressure to a rear wheel of the bicycle without actuating the front brake caliper.

Another exemplary brake caliper for a bicycle disclosed herein includes a caliper housing that is intended to be coupled to a bicycle near the rear wheel of the bicycle. The caliper housing includes a first port that is intended to be fluidly coupled to a first fluid line that is fluidly coupled to a first master piston chamber, a second port that is intended to be fluidly coupled to a second fluid line that is fluidly coupled to a front brake caliper, a third port that is intended to be fluidly coupled to a third fluid line that is fluidly coupled to a second master piston chamber, and a master slave piston chamber. The third port is fluidly coupled to the master slave piston chamber so that pressurization of the brake fluid in the second master piston chamber increases the pressure in the master slave piston chamber to actuate the rear brake caliper. The caliper housing also includes a secondary slave piston chamber isolated from the primary slave piston chamber. The first port is fluidly coupled to the secondary slave piston chamber so that pressurization of the brake fluid in the first primary fluid chamber increases the pressure in the secondary slave piston chamber to actuate the rear brake caliper.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Braking on modern bicycles has evolved to use technology from automotive brake systems such as hydraulic disc brakes. Hydraulic disc brakes have greater stopping power and deceleration control than the traditional rim and cable-pull brakes used in the past. Typically, bicycles using hydraulic disc brakes have one front brake and one rear brake to minimize stopping distance. In fact, this dual disc brake configuration is even a requirement in some countries. Bicycles and their riders, as well as similar two-wheeled vehicles, have a relatively high center of gravity and a short wheelbase length. The greater stopping power and high center of gravity of modern bicycles place the rider at risk of front wheel rollover during emergency or aggressive braking events. Specifically, when excessive front braking is experienced, the rear wheel may lift off the ground. This reduces control of the bicycle. Furthermore, in extreme cases, the rider may tip over the handlebars of the bicycle, which may cause serious injury to the rider and/or others around the rider.

Some known anti-rollover brake systems exist for cable-pulled rim brakes. In these known systems, a brake lever is used to directly apply the rear brakes. As the rear brakes generate braking force at the rim, movement of a sliding brake pad causes the force to be transmitted via a cable to a front brake caliper, thereby applying the front brake. Thus, two brakes are applied to minimize stopping distance. If the rear wheel leaves the ground in a possible rollover event, the rear brake force at the rim becomes zero, the sliding brake pads retract, and the front brake force drops to zero. The rear wheel then returns to the ground, eliminating the possibility of a rollover event. However, these known systems are only applicable to cable pull wheel rim brakes. In addition, these known systems only provide a brake lever for actuating two brakes simultaneously.

Other known anti-rollover braking systems utilize electronic control of the front brakes. These known electronic systems require onboard battery power and complex sensing systems to detect a rollover event. When the electronic system senses a rollover event, a pressurized fluid transfer of the front brake force is provided to reduce the front brake force and mitigate the rollover event. One disadvantage of this known electronic system is that with each successive fluid transfer with each single lever pull, the brake lever moves closer to the handlebar grip. If the brake lever moves sufficiently close to the grip, the electronic control system stops this transfer process, which eliminates any rollover control. Other disadvantages include the additional weight and complexity added to the bicycle, reliance on rechargeable batteries, and expensive electronic components.

Disclosed herein are exemplary brake systems and apparatus for providing rollover control on a bicycle that address many of the shortcomings of the known systems described above. The examples disclosed herein may be implemented with hydraulic disc brakes. The exemplary brake systems and apparatus disclosed herein detect when a rear wheel of a bicycle has lifted off the ground and reduce brake pressure on the front wheel, thereby reducing or preventing the possibility of a rollover. In addition, the exemplary brake systems and apparatus disclosed herein enable the rear brake to be controlled independently of the front brake. For example, a front brake actuator may be used to actuate the front brake, and a rear brake actuator may be used to actuate the rear brake without actuating the front brake. Thus, the rear brake actuator may be used to operate the rear brake independently of the front brake.

An exemplary brake system disclosed herein includes a front brake actuator, a rear brake actuator, a front brake including a front brake disc and a front brake caliper, and a rear brake including a rear brake caliper and a rear brake caliper. The front brake actuator is fluidly coupled to the front brake caliper through the rear brake caliper. In particular, the brake system includes a first fluid circuit (e.g., a hydraulic hose) fluidly coupling the front brake actuator and the rear brake caliper. In addition, the brake system includes a second fluid circuit fluidly coupling the rear brake caliper and the front brake caliper. The rear brake caliper includes a caliper housing having a first port fluidly coupled to the first fluid circuit, and a second port fluidly coupled to the second fluid circuit. The rear brake caliper includes a valve between the first port and the second port (and thus between the first fluid circuit and the second fluid circuit). The valve is operable to affect fluid flow or fluid communication between the first port and the second port, thereby affecting the application of braking pressure to the front wheel. For example, the valve is operable between an open state (e.g., a first state) and a closed state (e.g., a second state). In the on state, the first fluid circuit is fluidly coupled to the second fluid circuit, and thus, the front brake actuator can be actuated to supply brake fluid to the front brake caliper or release brake fluid from the front brake caliper. Thus, the front brake actuator can be used to apply brake pressure to the front brake caliper or release brake pressure on the front brake caliper.

In certain examples, the valve may be switched to the closed state when the rear wheel is lifted from the ground and/or has otherwise reduced traction. In the closed state, the valve fluidly isolates or disconnects the first port and the second port (and, therefore, fluidly isolates the first flow line and the second fluid line). Thus, further actuation of the front brake actuator does not increase braking pressure on the front wheel. Instead, because braking pressure from the front brake actuator is disconnected by closing the valve, the front brake caliper and the brake fluid in the second fluid line rebound or flow back in the opposite direction (toward the valve) and decrease in pressure, thereby reducing the braking force on the front wheel. With less braking force at the front wheel, the front wheel is able to spin slightly faster. As a result, the rear wheel is lowered back to the ground.

As described above, the valve switch can switch between the open and closed states depending on whether the rear wheel is in contact with the ground. In some examples, the state of the valve is controlled at least in part based on the position and/or movement of the caliper housing. For example, the caliper housing can be coupled to the frame of the bicycle (e.g., via a bracket) so that the rear brake caliper housing can pivot or rock between two positions (e.g., a forward position and a rearward position). When the front brake is actuated, brake fluid is supplied to one or more secondary slave pistons that actuate the rear brake caliper. The secondary slave pistons force one or more rear brake pads to engage with the rotating rear brake disc. When the rear wheel rotates, such as when the rear wheel contacts the ground, the frictional engagement between the rear brake pad(s) and the rotating rear brake disc biases the caliper housing in a forward direction (e.g., the forward rotational direction of the rear wheel) to the forward position. In this position, the caliper housing generates a rear braking force on the flow control member of the valve, and the valve maintains the flow control member in the open position. Therefore, as long as the rear wheel contacts the ground and rotates, the rear braking force generated by the frictional engagement maintains the valve in the open state.

However, if the rear wheel lifts from the ground (e.g., as a result of excessive front braking) and/or otherwise has reduced traction (e.g., when the rear wheel begins to lift and has minimal contact or traction with the ground), friction between the rear brake pad(s) and the rear brake disc causes the rear brake disc (and, therefore, the wheel) to stop rotating. When the rear wheel is no longer rotating, the rear brake force previously applied to the valve is removed. This removal of the rear brake force allows the flow control member to move to a closed position to switch the valve to the closed state. In some examples, movement of the flow control member to the closed position pushes the caliper housing to a rearward position in a rearward direction opposite the forward direction. In some examples, the valve is implemented as a spool valve with a movable shuttle. In some such examples, the pressure of the brake fluid in the valve causes the shuttle (the flow control member) to move to the closed position, which pushes the caliper housing in the rearward direction. When the shuttle is in the closed position, the valve fluid isolates the front brake actuator and the front brake caliper, thereby reducing the brake pressure on the front wheel and allowing the rear wheel to return to the ground.

If the rear wheel returns to the ground, the rear wheel begins to rotate again. Friction between the rear brake pad(s) and the rear brake causes the caliper housing to return to the forward position and reopen the valve (e.g., by moving the shuttle to the open position). Thus, fluid communication is reestablished between the front brake actuator and the front brake caliper. Thus, movement of the caliper housing may cause a change in the state of the valve and/or otherwise affect the flow characteristics of the valve. As the rear wheel moves away from the ground or toward the ground, the valve may rapidly alternate or oscillate between the open and closed states to control the braking force on the front wheel. Various different examples are disclosed herein where the valve is configured as a normally open valve or a normally closed valve. Certain examples disclosed herein utilize one or more springs to bias the valve to the normally open state or the normally closed state. Thus, the exemplary brake systems and apparatus can detect rear wheel lift (before a rider may be able to sense the rear wheel lift) and deactivate the front brakes, thereby allowing the rear wheel to return to the ground.

In addition, the exemplary brake system disclosed herein may include a third fluid line fluidically coupling the rear brake actuator and the rear brake caliper. The rear brake actuator can be actuated to supply brake fluid to the rear brake caliper through the third fluid line to actuate the rear brake caliper. The brake fluid used for the rear brake actuator and the brake fluid of the front brake actuator are isolated from each other. Thus, the exemplary brake system disclosed herein is capable of independent rear braking. Specifically, the rear brake actuator can be used to actuate the rear brake caliper without actuating the front brake caliper. Thus, unlike known systems that synchronize the front and rear brakes, the exemplary braking system disclosed herein enables a rider to independently control the front and rear brakes.

Furthermore, unlike known electronic anti-rollover systems, the exemplary brake systems and apparatus disclosed herein do not require any electronic devices (e.g., sensors, solenoids, etc.). Thus, the exemplary systems add less weight to the bicycle and do not require an onboard battery. Furthermore, the exemplary brake systems can be operated an unlimited number of times, whereas known electronic anti-rollover systems require regular charging or replacement of batteries.

Referring now to the drawings, FIG. 1 illustrates an example of a human-powered vehicle on which the exemplary brake systems and apparatus disclosed herein may be implemented. In this example, the vehicle is a bicycle 100 of one possible type, such as a mountain bike. In the illustrated example, the bicycle 100 includes a frame 102 and a front wheel 104 and a rear wheel 106 rotatably coupled to the frame 102. In the illustrated example, the front wheel 104 is coupled to the front end of the frame 102 via a front fork 108. In some examples, the front fork 108 includes one or more suspension components (e.g., a shock absorber) for absorbing shock or vibration. The rear wheel 106 is coupled to the frame 102 to support the rear end of the frame 102. In some examples, one or more suspension components may be coupled between the rear wheel 106 and the frame 102 to absorb shock or vibration. A front and/or forward riding direction or orientation of the bicycle 100 is represented by the direction of arrow A in FIG. 1 . Thus, a forward moving direction of the bicycle 100 is represented by the direction of arrow A. The bicycle 100 is shown riding on a riding surface 110. The riding surface 110 may be any riding surface, such as the ground (e.g., a dirt path, a walkway, a street, etc.), a man-made structure above the ground (e.g., a wooden ramp), and/or any other surface.

In the illustrated example, the bicycle 100 includes a seat 112 coupled to the frame 102 via a seat post 114 (e.g., near a rear end of the frame 102 relative to the forward direction A). The bicycle 100 also includes a handlebar 116 coupled to the frame 102 and the front fork 108 (e.g., near a forward end of the frame 102 relative to the forward direction A) for steering the bicycle 100. In the illustrated example, the bicycle 100 has a drive train 118 including a crank assembly 120. The crank assembly 120 is operatively coupled to a sprocket assembly via a chain 122. The sprocket assembly is part of an assembly mounted on a rear wheel hub 124, which provides a rotation axis for the rear wheel 106. The crank assembly 120 includes at least one, typically two, crank arms 126 and pedals 128, and at least one front chainwheel or sprocket 130. The exemplary bicycle 100 may include a rear gear change device (e.g., a shifter) and/or a front gear change device to move the chain 122 through different chainwheels.

The exemplary bicycle 100 of FIG. 1 includes an exemplary brake system 140 constructed according to the teachings of the present invention. The exemplary brake system 140 can be used to reduce the speed of the bicycle 100. The exemplary brake system 140 includes a front brake 142 for slowing the rotation of the front wheel 104 and a rear brake 144 for slowing the rotation of the rear wheel 106. In this example, the front brake 142 and the rear brake 144 are implemented as hydraulic disc brakes. The front brake 142 includes a front brake disc 146 and a front brake caliper 148. The front brake disc 146 is coupled to the front wheel hub 150 and rotates with the front wheel 104. The front brake caliper 148 is coupled to the front fork 108 and adjacent to the front brake disc 146. When the front brake caliper 148 is actuated, the front brake caliper 148 causes one or more brake pads to engage with the front brake disc 146 to slow the front brake disc 146 and, therefore, slow the rotation of the front wheel 104. As used herein, actuation of the front brake caliper 148 means that one or more brake pads are moved into engagement with the front brake disc 146. Similarly, the rear brake 144 includes a rear brake disc 152 and a rear brake caliper 154. The rear brake disc 152 is coupled to and rotates with the rear wheel 106 via the rear wheel hub 124. When the rear brake caliper 154 is actuated, the rear brake caliper 154 moves one or more brake pads into engagement with the rear brake disc 152 to slow the rear brake disc 152 and, therefore, slow rotation of the rear wheel 106. As used herein, actuation of the rear brake caliper 154 means that one or more brake pads are moved into engagement with the rear brake disc 152.

Although the exemplary bicycle 100 shown in FIG. 1 is a mountain bike, the exemplary brake systems and apparatus disclosed herein may be implemented on other types of bicycles. For example, the disclosed brake systems and apparatus may be used on road bicycles and bicycles having mechanical (e.g., cable, hydraulic, pneumatic, etc.) and non-mechanical (e.g., wired, wireless) drive systems. The disclosed brake systems and apparatus may also be implemented on other types of two, three, and four-wheeled human-powered vehicles. In addition, the exemplary brake systems and apparatus may be used on other types of vehicles, such as electric vehicles (e.g., motorcycles, cars, trucks, etc.).

FIG. 2 is an enlarged view of an exemplary brake system 140 as employed on the bicycle 100. As shown in FIG. 2, the brake system 140 includes a front brake actuator 200 for actuating the front brake caliper 148. The brake system 140 also includes a rear brake actuator 202 for actuating the rear brake caliper 154. In the illustrated example, the front and rear brake actuators 200, 202 are coupled to the handlebars 116. In this example, the front brake actuator 200 includes a front brake lever 204 and the rear brake actuator 202 includes a rear brake lever 206. However, in other examples, the front and rear brake actuators 200, 202 may include other types of hardware. In this example, the front brake actuator 200 is actuated by moving the front brake lever 204 toward the grip on the handlebars 116. As further disclosed herein, this actuation causes brake fluid to be pushed into the front brake caliper 148 through one or more fluid lines. Conversely, the front brake actuator 200 is deactivated by releasing or moving the front brake lever 204 away from the grip, which relieves or reduces the braking pressure on the front brake caliper 148. The rear brake actuator 202 and rear brake lever 206 operate similarly with respect to the rear brake caliper 154.

Typically, hydraulic disc brakes provide a relatively high deceleration rate. Therefore, riders often prefer disc brakes over other types of brakes. However, this ability to stop or slow down relatively quickly can also be unsafe. Referring again to FIG. 1 , FIG. 1 shows the traction required to decelerate bicycle 100. FIG. 1 also shows the typical position of the center of gravity (COG) of the rider and bicycle 100. The COG opposes the traction during braking-induced deceleration. The center of gravity is substantially higher than the traction on wheel 104, and combined with the relatively short wheel base, can lead to rollover events during aggressive braking. Specifically, in conventional brake systems, if the rider applies too much braking force to the front brake, the rear wheel 106 will lift off the riding surface 110. This causes a loss of control of the bicycle 100. In addition, in some cases, the rider may tip over the handlebars 116 and fall from the bicycle 100, which may cause serious injury to the rider.

The exemplary braking systems and apparatus disclosed herein prevent or reduce the possibility of the rear wheel 106 lifting off the riding surface 110 and assist the rider in maintaining control. As further disclosed herein in detail, the exemplary braking systems and apparatus disclosed herein modulate or reduce the braking pressure on the front wheel 104 when the rear wheel 106 is detected to be lifting off the riding surface 110. As a result, the traction at the front wheel 104 is reduced, thereby returning the rear wheel 106 to the riding surface 110.

To fluidly couple the front brake actuator 200 to the front brake caliper 148, the brake system 140 of FIGS. 1 and 2 includes a first fluid line 160 (e.g., hose, tubing, etc.) fluidly coupled between the front brake actuator 200 and the rear brake caliper 154, and a second fluid line 162 fluidly coupled between the rear brake caliper 154 and the front brake caliper 148. Thus, brake fluid for actuating the front brake caliper 148 is directed through the rear brake caliper 154 and to the front brake caliper 148. Thus, in this example, the front brake actuator 200 is not directly fluidly coupled to the front brake caliper 148. Conversely, the front brake actuator 200 is fluidly coupled to the front brake caliper 148 via the rear brake caliper 154. As described in further detail herein, the rear brake caliper 154 is configured to prevent excessive braking pressure on the front brake caliper 148 when the rear wheel 106 is lifted from the riding surface 110. The brake system 140 also includes a third fluid line 164 fluidly coupled between the rear brake actuator 202 and the rear brake caliper 154.

As shown in FIG2 , the front brake actuator 200 includes a first master piston chamber 208 having a first master piston 210. The first master piston chamber 208 contains brake fluid (first brake fluid). When the front brake actuator 200 is actuated, for example, by moving the front brake lever 204 toward the handles 116, the first master piston 210 moves (e.g., to the right in FIG2 ) to pressurize and displace the brake fluid in the first master piston chamber 208. Thus, the brake fluid is pushed through the first fluid line 160 to the downstream source. Conversely, when the front brake actuator 200 is released or deactivated, such as by moving the front brake lever 204 away from the handlebars 116, the pressure in the first master piston chamber 208 decreases, which draws the brake fluid back into the first master piston chamber 208 and reduces the pressure at the downstream source. In some examples, the front brake lever 204 may automatically move back to the initial position after the rider releases the front brake lever 204. As used herein, actuation of the front brake actuator 200 and/or the front brake lever 204 means increasing the pressure in the first master piston chamber 208 to move the brake fluid toward the downstream source and/or increase the pressure at the downstream source(s). Similarly, as used herein, release of the front brake actuator 200 and/or the front brake lever 204 means reducing the pressure in the first master piston chamber 208 to move brake fluid away from the downstream source(s) and/or reduce the pressure at the downstream source(s).

In this example, the first fluid line 160 fluidly couples the first master piston chamber 208 and the rear brake caliper 154. Thus, when the front brake actuator 200 is actuated, the brake fluid is pushed through the first fluid line 160 to the rear brake caliper 154. In certain instances, as disclosed in further detail herein, the brake fluid and/or increased pressure of the brake fluid is transmitted through the rear brake caliper 154 to the second fluid line 162 and, therefore, to the front brake caliper 148. Such supply of brake fluid or increase in the pressure of the brake fluid actuates the front brake caliper 148, thereby applying braking pressure to the front wheels 104. In other words, in some examples, when the front brake actuator 200 is actuated, the front brake actuator 200 supplies brake fluid to the front brake caliper 148 through the first fluid line 160, the rear brake caliper 154, and the second fluid line 162 to actuate the front brake caliper 148 to apply brake pressure to the front wheel 104. When the front brake actuator 200 is released, the brake fluid in the first fluid line 160 (and/or in the second fluid line 162) and/or the pressure of the brake fluid is released or moved back to the front brake actuator 200, thereby reducing the brake pressure caused by the front brake caliper 148 at the front wheel 104.

The rear brake actuator 202 similarly includes a second master piston chamber 212 having a second master piston 214. The second master piston chamber 212 contains brake fluid (second brake fluid). When the rear brake actuator 202 is actuated, such as by moving the rear brake lever 206 toward the handlebars 116, the second master piston 214 moves (e.g., to the right in FIG. 2 ) to pressurize and displace the brake fluid in the second master piston chamber 212. Thus, the brake fluid is pushed through the third fluid line 164 to the downstream source. Conversely, when the rear brake actuator 202 is released or deactivated, such as by moving the rear brake lever 206 away from the handlebars 116, the pressure in the second master piston chamber 212 decreases, which draws the brake fluid back into the second master piston chamber 212 and reduces the pressure at the downstream sources. In some examples, the rear brake lever 206 may automatically move back to the initial position after the rider releases the rear brake lever 206. As used herein, actuation of the rear brake actuator 202 and/or the rear brake lever 206 means increasing the pressure in the second master piston chamber 212 to move the brake fluid toward the downstream source(s) and/or increase the pressure at the downstream source(s). Similarly, as used herein, release of the rear brake actuator 202 and/or the rear brake lever 206 means reducing the pressure in the second master piston chamber 212 to move the brake fluid away from the downstream source(s) and/or reduce the pressure at the downstream source(s).

In this example, the third fluid line 164 fluidly couples the second master piston chamber 212 and the rear brake caliper 154. Therefore, when the rear brake actuator 202 is actuated, the brake fluid is pushed through the third fluid line 164 to the rear brake caliper 154. When the brake fluid in the third fluid line 164 is supplied to the rear brake caliper 154, the rear brake caliper 154 is actuated, thereby applying braking pressure to the rear wheel 106. When the rear brake actuator 202 is released, the brake fluid and/or the pressure of the brake fluid in the third fluid line 164 is relieved and/or moved back toward the rear brake actuator 202, thereby reducing the brake pressure caused by the rear brake caliper 154 at the rear wheel 106. The brake fluid in the third fluid line 164 is isolated or separated from the brake fluid in the first and second fluid lines 160, 162. Thus, actuation of the rear brake actuator 202 does not affect the brake pressure on the front wheel 104. In other words, the rear brake actuator 202 can be used to apply braking pressure to the rear wheel 104 without actuating the front brake caliper 148.

3A is a schematic diagram of an exemplary valve and fluid path configuration implemented by the brake system 140. FIG3A illustrates the state of the brake system 140 when neither the front brake actuator 200 or the rear brake actuator 202 is actuated. This may occur, for example, when the bicycle 100 ( FIG1 ) is in motion or at rest.

3A , the front brake actuator 200 is fluidly coupled to the rear brake caliper 154 via a first fluid line 160, the front brake caliper 148 is fluidly coupled to the rear brake caliper 154 via a second fluid line 162, and the rear brake actuator 202 is fluidly coupled to the rear brake caliper 154 via a third fluid line 164. The rear brake caliper 154 includes one or more primary slave piston chambers 300 for actuating the rear brake caliper 154. The rear brake caliper 154 also includes one or more secondary slave piston chambers 302 to actuate the rear brake caliper 154, as disclosed in further detail herein.

In the illustrated example, the rear brake caliper 154 includes a first port 304. The first fluid line 160 (which is fluidly coupled to the first master piston chamber 208 ( FIG. 2 )) is fluidly coupled to the first port 304. Thus, brake fluid can flow freely between the first master piston chamber 208 and the first port 304. The first port 304 can be formed by one or more passages (e.g., openings, bores, channels, etc.) or fluid lines. The rear brake caliper 154 also includes a second port 306. The second fluid line 162 is fluidly coupled to the second port 306. Thus, brake fluid can flow freely between the front brake caliper 148 and the second port 306. The second port 306 can be formed by one or more passages or fluid lines.

As shown in FIG3A , the rear brake caliper 154 includes a third port 308. The third fluid line 164 (which is fluidly coupled to the second master piston chamber 212 ( FIG2 )) is fluidly coupled to the third port 308. The third port 308 is fluidly coupled to the master slave piston chamber 300, and thus fluidly couples the third fluid line 164 and the master slave piston chamber 300. Thus, brake fluid may flow freely between the second master piston chamber 212 and the master slave piston chamber 300. The third port 308 may be formed by one or more passages or fluid lines. When the rear brake actuator 202 is actuated, the pressurization of the brake fluid in the second master piston chamber 212 increases the pressure in the primary slave piston chamber 300 to actuate the rear brake caliper 154 and apply braking pressure to the rear wheel 106 ( FIG. 1 ).

To control the flow of brake fluid between the first and second ports 304, 306 (and, therefore, between the front brake actuator 200 and the front brake caliper 148), the exemplary rear brake caliper 154 includes a valve 310 disposed between the first and second ports 304, 306. The valve 310 is operable to affect the flow of fluid between the first port 304 and the second port 306, thereby affecting the ability to apply brake pressure to the front wheel 104 (FIG. 1). One or more events may trigger the valve 310 to affect the flow of fluid between the first port 304 and the second port 306, as further described herein. In this example, the valve 310 is operable between an open state (a first state) and a closed state (a second state). In the open state, the first port 304 is fluidly coupled to the second port 306 so that brake fluid can flow between the first and second ports 304, 306, and therefore between the front brake actuator 200 and the front brake caliper 148. Thus, when the valve 310 is in the open state, the front brake actuator 200 can be used to apply brake pressure through the front brake caliper 148 or relieve brake pressure by the front brake caliper 148. In the closed state, the valve 310 blocks or isolates the first port 304 from the second port 306. Therefore, the front brake actuator 200 is fluidly isolated from the front brake caliper 148, which prevents pressure from being applied to the front brake caliper 148.

In this example, the valve 310 is implemented as a spool valve, referred to herein as the spool valve 310. However, in other examples, other types of valves or flow control devices may be implemented. The spool valve 310 has a valve housing 312 (e.g., a body) defining a chamber 314 and a shuttle 316 (which may be referred to as a flow control member) that is movably disposed in the chamber 314. The chamber 314 and the shuttle 316 define a first cavity 318, referred to herein as the neutral cavity 318, and a second cavity 320, referred to herein as the bias cavity 320. The first port 304 is fluidly coupled to the neutral cavity 318 and the second port 306 is fluidly coupled to the bias cavity 320. The shuttle 316 can move to allow or block the flow of fluid between the neutral cavity 318 and the biasing cavity 320. In particular, the shuttle 316 can move between an open position (a first position) and a closed position (a second position) to change the spool valve 310 between the open state and the closed state, respectively. In FIG. 3A , the shuttle 316 is in the open position and therefore, the spool valve 310 is in the open state.

In the illustrated example, the shuttle 316 includes a first spool 322 and a second spool 324 connected by a stem 326. The first and second spools 322, 324 may also be referred to as shaft rings or seals. In this example, the spool valve 310 includes a seat 328. When in the open position, as shown in Figure 3A, the second spool 324 is separated from the seat 328. Therefore, a transfer path 330 is defined between the second spool 324 and the seat 328, which enables fluid to flow between the neutral cavity 318 and the bias cavity 320, and therefore between the first port 304 and the second port 306. In other examples, the transfer path 330 can be implemented as a separate passage connected to two different locations in the chamber 314. In this example, when the shuttle 316 is in the open position, the passage connects the neutral cavity 318 and the biasing cavity 320. However, when the shuttle 316 moves to the closed position, both ends of the passage are in the biasing cavity 320, so that the neutral cavity 318 and the biasing cavity 320 are fluidly isolated from each other.

In this example, the spool valve 310 is configured as a normally open valve. In other examples, the spool valve 310 can be configured as a normally closed valve, examples of which are further disclosed in detail with reference to FIGS. 20A to 20D. In a normally open configuration, the shuttle 316 is biased to the open position. In this example, the spool valve 310 includes a biasing member, such as a spring 332. The spring 332 biases the shuttle 316 to the open position (left in FIG. 3A) so that the second spool 324 is separated from the seat 328. The spring 332 may be disposed inside the spool valve 310 or may be disposed outside the spool valve 310 (an example of which is further disclosed in detail with reference to FIG. 17A ). In the illustrated example, the spring 332 is a compression spring. However, in other examples, for example, when the spring 332 is located on the other side of the shuttle 316, the spring 332 may be implemented as an extension spring.

3B shows the exemplary valve and fluid path configuration of FIG. 3A when the front brake actuator 200 is actuated and the rear wheel 106 ( FIG. 1 ) rotates and maintains contact with the riding surface 110 ( FIG. 1 ). As indicated by the arrows, when the front brake actuator 200 is actuated, the front brake actuator 200 pushes the brake fluid through the first fluid line 160 and into the first port 304. The first port 304 is fluidly coupled to the secondary slave piston chamber 302. When the front brake actuator 200 is actuated, the brake fluid is displaced from the first master piston chamber 208 ( FIG. 2 ) to increase the pressure in the secondary slave piston chamber(s) 302, which causes one or more rear brake pads (e.g., rear brake pads 1100, 1202 shown in FIGS. 12 and 13 ) to engage the rear brake disc 152 ( FIG. 1 ) and thereby actuate the rear brake caliper 154. Thus, a biasing force is generated on the rear brake caliper 154 by the frictional engagement between the rear brake pad(s) and the rear brake disc 152. This biasing force is in the same direction as the forward rotation direction of the rear brake disc 152 and the rear wheel 106. When this biasing force is present, a rear braking force (as indicated by the arrow) is applied to the shuttle 316 of the spool valve 310 in the direction of the open position (to the left in FIG. 3B ), thereby biasing the shuttle 316 to the open position. In this example, the combination of the rear braking force and the force from the spring 332 biases the shuttle 316 to the open position. In some examples, a stop is engaged with the shuttle 316 so that when the rear brake caliper 154 is biased in the forward direction (the forward rotational direction of the rear brake disc 152), the stop is urged into the shuttle 316 in the opening direction. An example of such a stop is disclosed in further detail herein.

When the shuttle 316 is in the open position, the brake fluid is pushed through the neutral cavity 318, through the transfer path 330, through the biasing cavity 320, through the second port 306, and through the second fluid line 162 to the front brake caliper 148, thereby actuating the front brake caliper 148. Thus, braking pressure is applied to the front wheel 104 (Figure 1). Due to the rear brake force, the shuttle 316 is maintained in the open position. In detail, the combined force from the spring 332 and the rear brake force is greater than the force caused by the pressure of the brake fluid actuating in the opposite direction on the shuttle 316. Thus, as long as the rear wheel 106 (FIG. 1) is rotating (indicating contact with the riding surface 110 (FIG. 1)), the frictional engagement between the rear brake pad(s) and the rear brake disc 152 (FIG. 1) generates sufficient force to maintain the spool valve 310 in the open state. This allows brake fluid to flow back and forth between the front brake actuator 200 and the front brake caliper 148 as needed. Thus, a rider can use the front brake actuator 200 to apply braking pressure to the front wheel 104 or relieve braking pressure from the front wheel 104. In the absence of the rear braking force, the shuttle 316 can move to the closed position against the force from the spring 332, as further disclosed herein.

FIG. 3C shows the exemplary valve and fluid path configuration of FIGS. 3A and 3B when the front brake actuator 200 is actuated while the rear wheel 106 (FIG. 1) is lifted from the riding surface 110 (FIG. 1) and/or traction has otherwise been reduced. As described above, if too much brake pressure is applied to the front wheel 104 (FIG. 1), the rear wheel 106 lifts from the riding surface 110. When the rear wheel 106 lifts from the riding surface 110, the traction is reduced and/or eliminated. As a result, friction between the rear brake pad(s) and the rear brake disc 152 (FIG. 1) (applied by the pressure in the slave piston chamber(s) 302) stops the rear wheel 106 from rotating. This can occur relatively quickly because there is no friction from the riding surface 110 to rotate the rear wheel 106.

Once the rear wheel 106 has stopped rotating, the rear braking force (FIG. 3B) applied to the shuttle 316 ceases. In the absence of the rear braking force, the force from the brake fluid pressure in the neutral cavity 318 acting on the shuttle 316 overcomes the force from the spring 332 acting on the shuttle 316, causing the shuttle 316 to move to the closed position (right in FIG. 3C). When the shuttle 316 moves to the right in FIG. 3C, the second spool 324 sealingly engages the seat 328 and closes the transmission path 330 (FIG. 3A), as shown in the position of the shuttle 316 in FIG. 3C. In this position, the first port 304 is isolated or fluidly disconnected from the second port 306, and therefore, the front brake actuator 200 is disconnected from the front brake caliper 148. Therefore, the front brake actuator 200 cannot apply pressure to the front brake caliper 148. If the front brake actuator 200 is further actuated, the brake fluid is stopped in the neutral cavity 318 of the spool valve 310. The brake fluid in the second port 306, the second fluid line 162, and the front brake caliper 148 is disconnected from the fluid in the first port 304.

Once the shuttle 316 is in the closed position, the brake fluid in the second port 306, the second fluid line 162, and the front brake caliper 148 reduces pressure and flows back toward the spool valve 310. This is caused by the expansion of the biasing cavity 320 and the disconnection from the first port 304 (which was previously supplying the flow of brake fluid). The reduction in pressure reduces or relieves the braking pressure applied by the front brake caliper 148. As a result, the front wheel 104 (FIG. 1) can move faster, which reduces the amount of forward tilt and allows the rear wheel 106 (FIG. 1) to move rearward back onto the riding surface 110 (FIG. 1). Once the rear wheel 106 contacts the riding surface 110 again and begins to rotate, the rear braking force is again applied to the shuttle 316 (as shown in FIG. 3B ), thus moving the shuttle 316 back to the open position (to the left in FIG. 3C ). Once the shuttle 316 is in the open position, the pressure of the brake fluid in the first port 304 is again applied through the spool valve 310 to the second port 306 and to the front brake caliper 148. Thus, the spool valve 310 may oscillate or alternate between the open and closed states as the rear wheel 106 is lifted and lowered from the riding surface 110.

FIG. 3D shows the valve and fluid path configuration of FIGS. 3A to 3C when the front brake actuator 200 is released, such as when a rider intends to reduce the brake pressure on the front wheel 104 ( FIG. 1 ). When the front brake actuator 200 is released, the brake fluid in the first port 304 and the first fluid line 160 moves back toward the front brake actuator 200. The pressure in the secondary slave piston chamber 302 is reduced, which releases the brake pressure at the rear wheel 106 ( FIG. 1 ). Further, the pressure in the neutral cavity 318 of the spool valve 310 can be reduced. If the shuttle 316 was previously in the open position (such as in FIG. 3B ), this pressure reduction relieves the brake pressure at the front brake caliper 148. If the shuttle was previously in the closed position (such as in FIG. 3C ), and the pressure in the neutral cavity 318 and the rear brake pressure are reduced (e.g., to zero or substantially zero), the force from the spring 332 pushes the shuttle 316 to the open position (left in FIG. 3D ), thereby reopening the spool valve 310. Thus, the transmission path 330 is reopened, and the pressure at the front brake caliper 148 is reduced. The brake fluid moves from the front brake caliper 148 through the spool valve 310 and toward the front brake actuator 200 as shown by the arrow.

The rear brake actuator 202 can be used to actuate the rear brake caliper 154 independently of the front brake caliper 148. When the rear brake actuator 202 is actuated, the rear brake actuator 202 supplies brake fluid through the third port 308 and into the primary slave piston chamber 300 to cause the rear brake pad(s) to engage the rear brake disc 152 (FIG. 1) to apply brake pressure to the rear wheel 106 (FIG. 1). Conversely, when the rear brake actuator 202 is released or moved in the opposite direction, the brake fluid moves back toward the rear brake actuator 202, thereby relieving the brake pressure at the rear brake caliper 154. The caliper 154 isolates the third port 308 from the first and second ports 304, 306. Thus, the rear brake actuator can be used to actuate the rear brake caliper 154 independently of the front brake caliper 148. This allows a rider to have control over the rear brake pressure independently of the front brake pressure. In some examples, the primary slave piston chamber(s) 300 are larger (e.g., have a larger diameter) than the secondary slave piston chamber 302. Thus, actuation of the secondary slave piston chamber 302 applies less braking pressure to the rear brake disc 152.

Although in this example, the rear brake caliper 154 includes one or more master-slave piston chambers 300 for independently actuating the rear brake caliper 154, in other examples, the master-slave piston chamber(s) 300 may be omitted. Instead, the only actuation of the rear brake caliper 154 may come from the front brake actuator 200. Furthermore, although in the illustrated example, the fluid lines 160, 162, 164 are used to transmit fluid pressure, in other examples, cables rather than fluid lines may be used to transmit force.

In some examples, when the spool valve 310 is in the closed state, a bypass passage and check valve may be used to more quickly relieve the pressure in the front brake caliper 148 when the front brake actuator 200 is released. For example, as disclosed above, when the shuttle 316 is in the closed position (the position shown in FIG. 3C ) and the front brake actuator 200 is released to reduce the brake pressure, the pressure in the spool valve 310 is reduced and the shuttle 316 moves back to the open position (the position shown in FIG. 3D ). However, this movement may take a small amount of time, during which pressure is still applied to the front brake caliper 148. Therefore, in some examples, the rear brake caliper 154 may include a bypass passage and a check valve to relieve pressure more quickly.

For example, FIG4 shows the exemplary valve and fluid passage configuration of FIGS. 3A-3D with an exemplary bypass passage 400. The bypass passage 400 fluidly couples the first port 304 and the second port 306 (and/or the neutral cavity 318 and the bias cavity 320), thereby bypassing the transmission path 330 of the spool valve 310. As shown in FIG4, a check valve 402 is disposed in the bypass passage 400. When the pressure in the second port 306 is higher than the pressure in the first port 304, the check valve 402 allows the brake fluid to flow from the second port 306 to the first port 304, but prevents the brake fluid from flowing from the first port 304 to the second port 306. Therefore, when the front brake actuator 200 is released and the shuttle 316 is initially in the closed position, the brake fluid in the front brake caliper 148 flows through the check valve 402 to the first port 304 to relieve the brake pressure more quickly while the shuttle 316 moves to the open position (to the left in FIG. 4 ).

FIGS. 5-20 illustrate exemplary physical implementations of a rear brake caliper 154 having the exemplary valve and fluid passage configurations shown in the schematic diagrams of FIGS. 3A-4 . In other examples, other valve and fluid passage configurations may be implemented in the brake system 140. Other exemplary valve and fluid passage configurations are further disclosed in detail with respect to FIGS. 20A-20D and 21A-21D .

FIG. 5 shows a rear brake caliper 154 coupled to a frame 102 of a bicycle 100. In the illustrated example, the rear brake caliper 154 includes a caliper housing 500 and a hinge mechanism 501. The caliper housing 500 is coupled to the frame 102 of the bicycle 100 via the hinge mechanism 501. The hinge mechanism 501 enables the caliper housing 500 to move (e.g., hinge, pivot, rock, etc.) relative to the frame 102 of the bicycle 100 and the rear brake disc 152. In this example, the hinge mechanism 501 includes a bracket 502 (e.g., a mounting member). As shown in FIG. 5 , a bracket 502 is coupled to the frame 102, and a caliper housing 500 is coupled to the bracket 502. Thus, the caliper housing 500 is coupled to the bicycle 100 via the bracket 502. In the illustrated example, the bracket 502 is fixedly coupled to the frame 102 near the rear wheel 106 via two fasteners 504, 506 (e.g., bolts). In other examples, the bracket 502 may be coupled to the frame 102 via only one fastener or more than two fasteners. In other examples, the bracket 502 may be coupled to the frame 102 via one or more other mechanical or chemical fastening techniques (e.g., welding, clips, etc.). In still other examples, the bracket may be integrally formed as a structure of the frame. In some examples, the hinge mechanism 501 includes one or more swing arms (e.g., the front swing arm 604 and the rear swing arm 614 disclosed in further detail with respect to FIGS. 6 and 7 ) that move the caliper housing 500 relative to the bracket 502 and, therefore, relative to the frame 102 and the rear brake disc 152. In other examples, the caliper housing 500 may instead be directly coupled to the frame 102 of the bicycle 100 without the bracket 502 (e.g., via the one or more swing arms). Thus, while many of the examples disclosed herein are described with respect to moving the caliper housing 500 relative to the bracket 502, it should be understood that the caliper housing 500 may be similarly movably coupled directly to the frame 102 of the bicycle 100 without the bracket 502. Movement of the caliper housing 500 affects the state and/or flow characteristics of the valve 310 (FIG. 3A), as further disclosed herein. The caliper housing 500 receives the rear brake disc 152. When actuated, the rear brake caliper 154 pushes one or more rear brake pads into engagement with the rear brake disc 152 to thereby slow the rear wheel 106.

6 and 7 are perspective views of the rear brake caliper 154. As disclosed above, the caliper housing 500 can move relative to the bracket 502 (e.g., via rocking or pivoting motion). As shown in FIG. 6 , a front end 600 of the caliper housing 500 is coupled to a front end 602 of the bracket 502 via a front rocker arm 604. Specifically, in the illustrated example, the front end 600 of the caliper housing 500 is coupled to the front rocker arm 604 via a first pin 606, and the front end 602 of the bracket 502 is coupled to the front rocker arm 604 via a second pin 608. Thus, the front end 600 of the caliper 500 can be articulated (e.g., pivoted, rocked, etc.) relative to the front end 602 of the bracket 502.

Similarly, as shown in FIGS. 6 and 7 , the rear end 610 of the caliper housing 500 is coupled to the rear end 612 of the bracket 502 via a rear rocker arm 614. In the illustrated example, the rear end 610 of the caliper housing 500 is coupled to the rear rocker arm 614 via a first pin 616, and the rear end 612 of the bracket 502 is coupled to the rear rocker arm 614 via a second pin 618. Thus, the rear end 610 of the caliper housing 500 can rotate (e.g., pivot, rock, etc.) relative to the rear end 612 of the bracket 502. The caliper housing 500 can move between a forward position and a rearward position relative to the bracket 502, as further disclosed herein.

As shown in FIGS. 6 and 7 , the rear brake caliper 154 also includes a spring 622. The spring 622 corresponds to the spring 332 ( FIGS. 3A to 4 ), which biases the shuttle 316 toward the open position. In this example, the spring 622 is outside the spool valve 310. However, in other examples, the spring 622 may be inside the check valve 310. In the illustrated example, the spring 622 is an extension spring coupled between the caliper housing 500 and the bracket 502. The spring 622 biases the caliper housing 500 in a forward direction (which corresponds to the open state of the spool valve 310). In other examples, a compression spring may be used to bias the caliper housing 500 in addition to or as an alternative to the spring 622. For example, a compression spring may be disposed between the rear swing arm 614 and the bracket 502. In other examples, the spring 622 (and/or the compression spring) may be coupled between other components of the caliper housing 500, the bracket 502, and/or the frame 102 (FIG. 1) of the bicycle 100 (FIG. 1). Also shown in FIGS. 6 and 7 is the valve housing 312 of the spool valve 310. The valve housing 312 is coupled to the caliper housing 500. In the illustrated example, the clamp housing 500 and the valve housing 312 are two separate components or assemblies. However, in other examples, the clamp housing 500 and the valve housing 312 can be constructed as a single unit housing or body.

7 , the first, second, and third fluid lines 160, 162, 164 are fluidly coupled to the rear brake caliper 154. In this example, the first fluid line 160, the second fluid line 162, and the third fluid line 164 are coupled to the rear brake caliper 154 via respective banjo bolts and joints. For example, the first fluid line 160 is fluidly coupled to the caliper housing 500 via a first banjo bolt 700 and a first joint 702, the second fluid line 162 is fluidly coupled to the valve housing 312 via a second banjo bolt 704 and a second joint 706, and the third fluid line 164 is fluidly coupled to the caliper housing 500 via a third banjo bolt 708 and a third joint 710. This allows fluid communication between the first, second and third fluid lines 160, 162, 164 and their respective ports on the rear brake caliper 154. In other examples, other types of attachment mechanisms (e.g., expansion joints) may be used.

Fig. 8 and Fig. 9 are side views of the rear brake caliper 154. In the illustrated example, the caliper housing 500 is in a forward state or position. The caliper housing 500 can be moved (e.g., rocked) in a relative direction to a rear state or position, which is further shown in detail with respect to Fig. 18A. As shown, the spring 622 is configured to bias the caliper housing 500 in a forward direction (leftward in Fig. 8 and rightward in Fig. 9), and the forward rotation direction corresponds to the forward rotation direction of the rear wheel 106 (Fig. 1) and the rear brake disc 152 (Fig. 1). In the illustrated example, a first stopper or buffer 800 is coupled to the bracket 502. In the forward position, the clamp housing 500 engages the first buffer 800. The size of the first buffer 800 and/or the position of the buffer 800 can be changed to change the position of the clamp housing 500 in the forward position.

In order to transmit the rear braking force (if any) to the shuttle 316 (inside the valve housing 312), the rear brake caliper 154 includes a stop 802, as shown in FIG8. In the illustrated example, the stop 802 is coupled to and extends from the front rocker arm 604. The stop 802 engages with the shuttle 316 of the spool valve 310 and/or otherwise provides a biasing force, as further disclosed herein. When the caliper housing 500 is in the forward position, as shown in the position in FIG8, the stop 802 is positioned close to or within the spool valve 310. However, when the caliper housing 500 moves to the rearward position (rightward in FIG. 8 ), the front end 600 of the caliper housing 500 moves away from the front end 602 of the bracket 502, causing the stop 802 to move away from or away from the spool valve 310. In some examples, this movement is caused by the shuttle 316 moving from an open position to a closed position.

FIG. 10 is a cross-sectional view of the rear brake caliper 154 taken along line A-A of FIG. 6. As shown in FIG. 10, the caliper housing 500 includes a first primary piston chamber 300a, which corresponds to one of the primary slave piston chambers 300 in FIGS. 3A to 4. A first primary piston 1000 is disposed in the first primary piston chamber 300a and is movable in the primary piston chamber 300a. As disclosed herein, the third fluid line 164 is fluidly coupled to the first primary piston chamber 300a. Therefore, when the rear brake actuator 202 (FIG. 2) is actuated, the first primary piston 1000 is moved (off the page in FIG. 10).

As shown in FIG. 10 , the caliper housing 500 also includes a first secondary piston chamber 302a, which corresponds to one of the secondary slave piston chambers 302 in FIGS. 3A to 4 . A first secondary piston 1002 is disposed in the first secondary piston chamber 302a and is movable in the first secondary piston chamber 302a. In some examples, the first fluid line 160 is fluidly coupled to the first secondary piston chamber 302a. Thus, when the front brake actuator 200 ( FIG. 2 ) is actuated, the first secondary piston 1002 is moved (off the page in FIG. 10 ). The first primary piston chamber 300a is fluidly isolated from the first secondary piston chamber 302a.

FIG. 11 is a cross-sectional view of the rear brake caliper 154 taken along line B-B of FIG. 6 . The cross-sectional view is taken substantially around the center of the caliper housing 500. As shown in FIG. 11 , the rear brake caliper 154 has a first rear brake pad 1100. The first rear brake pad 1100 is movably coupled to the caliper housing 500. In this example, the first rear brake pad 1100 can slide along a pin 1102 extending from the caliper housing 500. The first primary piston 1000 ( FIG. 10 ) and the first secondary piston 1002 ( FIG. 10 ) are coupled to a back side of the first rear brake pad 1100. Thus, when either the first primary piston 1000 or the first secondary piston 1002 or both are actuated, the rear brake pad 1100 is moved (off the page in FIG. 11 ) and engages the rear brake disc 152 ( FIG. 1 ). The rear brake caliper 154 may also have a second rear brake pad on the opposite side of the rear brake disc 152 that is similarly configured to move and engage the other side of the rear brake disc, as shown with respect to FIG. 12 . As shown in FIG. 10 , the first secondary piston chamber 302a is smaller in diameter than the first primary piston chamber 300a. Thus, actuating the rear brake caliper 154 via the first secondary piston chamber 302a results in less braking force than actuating the rear brake caliper 154 via the first primary piston chamber 300a.

As shown in FIG. 11 , the spool valve 310 includes a shuttle 316 disposed in a valve housing 312. The shuttle 316 is movable to change the state of the spool valve 310. In the illustrated example, a stop 802 engages the shuttle 316. The shuttle 316 is movable between the open position and the closed position to move the spool valve 310 between the open state and the closed state. When the front brake actuator 200 ( FIG. 1 ) is actuated and the rear wheel 106 ( FIG. 1 ) is in contact with the riding surface 110 ( FIG. 1 ) and rotates, the stop 802 (via a biasing force from the rear brake force) keeps the shuttle 316 in the open position. However, when the front brake actuator 200 is actuated and the rear wheel 106 is lifted from the riding surface 110 and stops rotating, the shuttle 316 moves to the closed position, thereby closing the spool valve 310. Examples of these positions and states are further disclosed in detail with respect to FIGS. 17A-18B .

FIG. 12 is a cross-sectional view of the rear brake caliper 154 taken along line C-C of FIG. 7. FIG. 12 shows a first primary piston chamber 300a and a second primary piston chamber 300b formed in an opposite side of the caliper housing 500. A second primary piston 1200 is movably disposed in the second primary piston chamber 300b. A second rear brake pad 1202 is movably coupled to the caliper housing 500. The second primary piston 1200 is coupled to the second rear brake pad 1202. The rear brake disc 152 (FIG. 1) is intended to be disposed between the first and second rear brake pads 1100, 1202.

As disclosed herein, the rear brake caliper 154 includes a third port 308 that fluidly couples the third fluid circuit 164 ( FIG. 1 ) to the primary slave piston chamber 300 (e.g., such as the first and second primary piston chambers 300a, 300b). The third port 308 can be formed by one or more fluid passages. For example, as shown in FIG. 12 , the caliper housing 500 includes a third inner bore 1204 (the first inner bore and the second inner bore are disclosed in further detail below). A third hollow bolt 708 is threadedly inserted into the third inner bore 1204. The third hollow bolt 708 has an internal passage 1206. The third fluid line 164 is fluidly coupled to an internal passage 1206 of the third hollow bolt 708 (an example of which is shown with respect to the second hollow bolt 704 in FIG. 16 ) through the third joint 710 and through an opening in the third hollow bolt 708. The third hollow bolt 708 includes one or more openings 1208 that connect the internal passage 1206 to the outside of the third hollow bolt 708 and thus to the third inner bore 1204. In the example shown, the caliper housing 500 includes a first passage 1210 that fluidly couples the third inner bore 1204 with the first primary piston chamber 300a and a second passage 1212 that fluidly couples the third inner bore 1204 with the second primary piston chamber 300b. Thus, the brake fluid can flow freely between the third fluid line 164 (FIG. 1) and the first and second main piston chambers 300a, 300b. In this example, the third inner bore 1204 and the first and second passages 1210, 1212 form a third port 308. In other examples, the third port 308 can be formed by more or fewer passages, and/or the passages can be arranged in other configurations.

When the rear brake actuator 202 ( FIG. 2 ) is actuated, for example, brake fluid is pushed through the third port 308 and into the first and second primary piston chambers 300 a, 300 b to move the first and second primary pistons 1000, 1200 inward (toward each other), thereby moving the first and second rear brake pads 1100, 1202 into engagement with the rear brake disc 152 ( FIG. 1 ). Conversely, when the rear brake actuator 202 is released, the brake fluid is moved away from the first and second primary piston chambers 300a, 300b, thereby retracting the first and second primary pistons 1000, 1200 and moving the first and second rear brake pads 1100, 1202 away from the rear brake disc 152 to relieve the braking pressure on the rear brake disc 152.

FIG. 13 is a cross-sectional view of the rear brake caliper 154 taken along line D-D of FIG. 7. FIG. 13 shows a first secondary piston chamber 302a and a second secondary piston chamber 302b formed in opposite sides of the brake housing 500. A second secondary piston 1300 is movably disposed in the second secondary piston chamber 302b. The second secondary piston 1300 is coupled to the second rear brake pad 1202.

As disclosed herein, the rear brake caliper 154 includes a first port 304 that fluidly couples the first fluid line 160 to the secondary slave piston chamber(s) 302, such as the first and second secondary piston chambers 302a, 302b, and the spool valve 310 (FIG. 3). The first port 304 can be formed by one or more fluid passages. For example, as shown in FIG. 13, the caliper housing 500 includes a first inner bore 1302. The first inner bore 1302 is fluidly coupled to the first fluid line 160. Similar to the third hollow bolt 708 described above, the first hollow bolt 700 is threadedly inserted into the first inner bore 1302 and includes an internal channel 1304. The first fluid line 160 is fluidly coupled to the internal passage 1304 of the first hollow bolt 700 through the first connector 702 and through openings in the first hollow bolt 700 (one example of which is shown with respect to the second hollow bolt 704 in FIG. 16 ). The first hollow bolt 702 includes one or more openings 1306 that connect the internal passage 1304 to the outside of the first hollow bolt 700 and thus to the first inner bore 1302. In the illustrated example, the first passage 1308 fluidly couples the first inner bore 1302 and the first secondary piston chamber 302a, and the second passage 1310 fluidly couples the first inner bore 1302 and the second secondary piston chamber 302b. Thus, in this example, the first inner bore 1302 and the first and second passages 1308, 1310 form the first port 304. In other examples, the first port 304 may be formed by more or fewer vias and/or may be arranged in other configurations.

When the front brake actuator 200 ( FIG. 2 ) is actuated, for example, brake fluid is pushed through the first port 304 and into the first and second secondary piston chambers 302 a, 302 b to move the first and second secondary pistons 1002, 1300 inwardly, thereby moving the first and second rear brake pads 1100, 1202 into engagement with the rear brake disc 152 ( FIG. 1 ). Conversely, when the front brake actuator 200 is released, the brake fluid moves away from the first and second secondary piston chambers 302a, 302b, thereby retracting the first and second secondary pistons 1002, 1300 and moving the first and second rear brake pads 1100, 1202 away from the rear brake disc 152 to relieve braking pressure.

FIG. 14A is a cross-sectional view of the rear brake caliper 154 taken along line E-E of FIG. 6. As shown in FIG. 14A, the caliper housing 500 and the valve housing 312 include a third passage 1400, which fluidly couples the first inner bore 1302 and the spool valve 310. The third passage 1400 also forms part of the first port 304 (FIGS. 3 and 13). FIG. 14B is an enlarged view of the reference 1402 in FIG. 14A. As shown in FIG. 14B, the shuttle 316 is disposed in the chamber 314 of the valve housing 312. The chamber 314 and the shuttle 316 define a neutral cavity 318 and a biasing cavity 320. The third passage 1400 fluidly couples the first inner bore 1302 and the neutral cavity 318. An opening 1404 (e.g., an inlet/outlet) is shown in the biasing cavity 320 in FIG. 14B , which can be used as a drain port to facilitate filling the system with brake fluid during assembly.

FIG. 15 is a cross-sectional view of the rear brake caliper 154 taken along line F-F of FIG. 6 . As disclosed herein, the rear brake caliper 154 includes a second port 306 that fluidly couples the second fluid line 162 to the spool valve 310. The second port 306 can be defined by one or more fluid passages. For example, as shown in FIG. 15 , the valve housing 312 includes a second inner bore 1500. Similar to the first hollow bolt 700 and the third hollow bolt 708 described above, the second hollow bolt 704 is threadedly inserted into the second inner bore 1500 and includes an internal passage 1502. The second fluid line 162 is fluidly coupled to the internal passage 1502 of the second hollow bolt 704 through the second connector 706 and through an opening in the second hollow bolt 704 (one example of which is shown in the example of FIG. 16 ). The internal passage 1502 extends to one end of the second hollow bolt 704. Thus, the second fluid line 162 is fluidly coupled to the second inner bore 1500. The second inner bore 1500 leads to an opening 1504 (inlet/outlet) in the biasing cavity 320 of the spool valve 310. Thus, in this example, the second inner bore 1500 forms the second port 306. In other examples, the second port 306 may be formed by more or fewer passages, and/or the passage(s) may be arranged in other configurations.

FIG. 16 is a cross-sectional view of the rear brake caliper 154 taken along line G-G of FIG. 7 . FIG. 16 shows the second inner bore 1500 (which forms the second port 306) which leads to the biasing cavity 320 of the spool valve 310. FIG. 16 also shows the connection between the second joint 706 and the internal passage 1502 of the second hollow bolt 704. Specifically, the second hollow bolt 704 includes an opening 1600 that extends through the second hollow bolt 704 into the internal passage 1502. The opening 1600 is aligned with the second joint 706. Therefore, the brake fluid in the second fluid line 162 (and in the second joint 706) communicates with the internal passage 1502 through the opening 1600, and vice versa. The first and third hollow bolts 700, 708 and their respective joints 702, 710 mentioned above may have similar structures.

FIG. 17A is a cross-sectional view of the rear brake caliper 154 taken along line H-H of FIG. 7. FIG. 17A shows the state of the rear brake caliper 154 when the front brake actuator 200 (FIG. 2) is actuated and the rear wheel 106 (FIG. 1) is rotated, such as when the rear wheel 106 is in contact with the riding surface 110 (FIG. 1). When the front brake actuator 200 is actuated, the brake fluid is pushed through the first port 304 (e.g., through the first inner bore 1302 and the first and second passages 1308, 1310 (FIG. 13)) and into the first and second secondary piston chambers 302a, 302b (FIG. 13). This causes the first and second rear brake pads 1100, 1202 (FIGS. 12 and 13) to engage the rear brake disc 152 (FIG. 1). Even though the first and second secondary master piston chambers 302a, 302b are smaller than the first and second primary piston chambers 300a, 300b, the first and second primary piston chambers 302a, 302b generate enough pressure to push the first and second rear brake pads 1100, 1202 to engage the rear brake disc 152 and provide some braking to the rear wheel 106. The frictional engagement between the first and second rear brake pads 1100, 1202 and the rear brake disc 152 biases the caliper housing 500 in the forward direction, as shown by the arrow in FIG. 17A. The forward direction is the forward rotation direction of the rear brake disc 152 and the rear wheel 106. Therefore, the caliper housing 500 is biased to the forward position shown in Figure 17A. In the forward position, the front end 600 of the caliper housing 500 is positioned downward, as shown in the position in Figure 17A. Thus, the stop 802 is forced against the shuttle 316, thereby biasing the shuttle 316 to the open position (left side in Figure 17A). The stop 802 provides a rear braking force (Figure 3B) to maintain the shuttle 316 in the open position. In other words, the stop 802 is biased against the shuttle 316 to maintain the shuttle 316 in the open position. In addition, the spring 622 biases the caliper housing 500 to the forward position and, therefore, biases the stop 802 in the opening direction against the shuttle 316. However, the spring 622 alone does not provide enough force to maintain the shuttle 316 in the open position.

FIG. 17B is an enlarged view of reference 1700 in FIG. 17A showing valve 310. As shown in FIG. 17B, shuttle 316 is slidably disposed within chamber 314 of valve housing 312. First spool 322 has substantially the same diameter as chamber 314 and is slidable along inner wall 1702 of chamber 314. In the example shown, a seal assembly 1704 is disposed in a gland 1706 (e.g., a groove) formed in first spool 322. Sealing assembly 1704 creates a seal between first spool 322 and inner wall 1702 to prevent leakage. In this example, sealing assembly 1704 includes a first O-ring 1708 and a first fastener 1710. In other examples, the sealing assembly 1704 may include more or fewer seals and/or other types of seals. A seat 328 is also shown in Figure 17B. In the example shown, the seat 328 is disposed in a pressure cover 1712 formed in the inner wall 1702. In this example, the seat 328 includes a second O-ring 1714 and a second fastener 1716. In other examples, the seat 328 may include more or fewer seals and/or other types of seals. In Figure 17B, the shuttle 316 is in an open position. In the open position, the second spool 324 is spaced apart from the second O-ring 1714 of the seat 328, allowing a transfer path 330 to be formed (to allow fluid to flow between the neutral cavity 318 and the biasing cavity 320).

When the front brake actuator 200 ( FIG. 2 ) is actuated and the shuttle 316 is in the open position, the brake fluid from the front brake actuator 200 is supplied to the neutral cavity 318 (e.g., via the third passage 1400 ( FIG. 14 )) via the first port 304 ( FIGS. 13 and 14A). The brake fluid flows from the neutral cavity 318, through the transfer path 330, and into the biasing cavity 320. From the biasing cavity 320, the brake fluid flows through the second port 306 ( FIGS. 15 and 16 ) to the second fluid line 162 ( FIG. 16 ), and thus, flows to the front brake caliper 148 to apply braking pressure on the front wheel 104. When the spool valve 310 is in the open state, the front brake actuator 200 is fluidly coupled to the front brake caliper 148 and can be used to apply or reduce braking pressure to the front brake caliper 148.

As shown in FIG17B , the stop 802 is engaged with the first spool 322. The stop 802 provides a force on the shuttle 316 in the open position direction (to the left in FIG17B ). This force is the result of the combination of the spring 622 ( FIG17A ) and the frictional force from the engagement between the rear brake pads 1100, 1202 ( FIGS. 12 and 13 ) and the rear brake disc 152 ( FIG1 ). The force of the pressure of the brake fluid in the neutral cavity 318 acting on the first spool 322 (on the left side of the first spool 322 in FIG17B ) is less than the force provided by the stop 802 on the first spool 322 (on the right side of the first spool 322 in FIG17B ). Therefore, as long as the rear wheel 106 rotates and friction forces bias the caliper housing 500 in the forward direction ( FIG. 17A ), the spool valve 310 remains in the open state. When the spool valve 310 is in the open state, brake fluid can flow freely between the front brake actuator 200 and the front brake caliper 148. Therefore, the front brake actuator 200 can be used to apply or reduce the braking pressure at the front brake caliper 148.

In this example, the rear brake caliper 154 includes the bypass passage 400 and the check valve 402. As disclosed herein, the bypass passage 400 and the check valve 402 can be used to more quickly relieve pressure from the front brake caliper 148 (FIG. 1) when the front brake actuator 200 (FIG. 2) is released. In this example, the bypass passage 400 and the check valve 402 are integrated into the shuttle 316. In particular, in this example, the bypass passage 400 extends between a first opening 1718 in the shuttle 316 that is in fluid communication with the neutral cavity 318 and a second opening 1720 in the shuttle 316 that is in fluid communication with the biasing cavity 320. In the illustrated example, the check valve 402 includes a ball 1722 (e.g., a flow control member) and a spring 1724. The spring 1724 biases the ball 1722 into a seal 1726 disposed in the bypass passage 400. When the pressure in the biasing cavity 320 is greater than the combined pressure of the neutral cavity 318 and the spring 1724, the ball 1722 moves away from the seal 1726 to allow fluid to flow from the biasing cavity 320 to the neutral cavity 320 (thereby bypassing the seat 328). However, the check valve 402 prevents fluid from flowing from the central cavity 318 to the biasing cavity 320 through the bypass passage 400.

In the illustrated example, the shuttle 318 is comprised of two parts or assemblies, a first assembly 1728 and a second assembly 1730. In some cases, this allows the check valve 402 in the shuttle 316 to be assembled more easily. In the illustrated example, the first assembly 1728 and the second assembly 1730 are threadedly coupled. However, in other examples, the shuttle 316 may be comprised of a single unitary part or assembly. In addition, although in this example, the bypass passage 400 and the check valve 402 are integrated into the shuttle 316, in other examples, the bypass passage 400 and the check valve may be separate from the shuttle 316. For example, the bypass passage 400 may be a separate passage formed in the valve housing 312 and/or the caliper housing 500 between the neutral cavity 318 and the biasing cavity 320 that bypasses the seat 328. In yet other examples, the rear brake caliper 154 may not include the check valve 402. In this example, the shuttle 316 may be formed from a single unitary component or assembly.

Fig. 18A shows the state of the rear brake caliper 154 when the front brake actuator 200 (Fig. 2) is actuated and the rear wheel 106 (Fig. 1) is lifted from the riding surface 110 (Fig. 1), and Fig. 18B is an enlarged view of the reference 1800 of the valve 310 in Fig. 18A. As described above, when the front brake actuator 200 is actuated, the rear brake pads 1100, 1202 (Figs. 12 and 13) are pushed into engagement with the rear brake disc 152 (Fig. 1). However, without the friction between the riding surface 110 and the rear wheel 106 to rotate the rear wheel 106, the friction between the rear brake pads 1100, 1202 and the rear brake disc 152 will cause the rear wheel 106 to stop rotating, which may occur quite quickly (e.g., 0.5 seconds). Once the rear wheel 106 stops rotating, the biasing force on the caliper housing 500 (provided by the brake pads 1100, 1202 and the brake disc 152) ceases. In this case, there is no rear braking force provided by the stop 802 on the shuttle 316. Instead, the only force provided by the stop 802 on the shuttle 316 is from the spring 622. Therefore, the force from the pressure in the neutral cavity 318 acting on the first spool 322 (on the left side of the first spool 322 in FIG. 18B ) is greater than the force provided by the stop 802 (on the right side of the first spool 322 in FIG. 18B ) on the first spool 322. Due to this force difference, the shuttle 316 moves to the closed position shown in FIGS. 18A and 18B . When the shuttle 316 moves to the closed position, the shuttle 316 pushes the stop 802 outward (to the right in FIGS. 18A and 18B ). This action causes the front rocker arm 604 to pivot the caliper housing 500 in a rearward direction. The rearward direction is opposite to or against the forward rotation direction of the rear wheel 106 ( FIG. 1 ) and the rear brake disc 152 ( FIG. 1 ). In other words, when the shuttle 316 moves to the closed position, the shuttle 316 moves the stop 802 and moves the caliper housing 500 toward the rearward position. As shown in FIG. 18A , the caliper housing 500 has moved to the rearward position (upward and leftward) away from the first buffer 800. Therefore, the movement of the shuttle 316 from the open position to the closed position causes the caliper housing 500 to move in the rearward direction.

As shown in FIG. 18A , in the rearward position, the rear rocker arm 614 has a second stop or bumper 1802 that engages the bracket 502 and prevents further movement in the rearward direction. The size and/or position of the stop 802, the first bumper 800, and the second bumper 1802, as well as other features of the example rear brake caliper 154 (e.g., the size of the spring 622), can be varied to affect the range of movement of the caliper housing 500 between the forward position and the rearward position. The size and position of these features can be varied for desired performance and rollover control sensitivity.

As shown in FIG. 18B , the second spool 324 sealingly engages the second O-ring 1714 of the seat 328, thereby isolating the neutral cavity 318 and the biasing cavity 320. This prevents further pressure from being applied to the front wheel 104 ( FIG. 1 ). Any further pressure is stopped in the neutral cavity 318. As the shuttle 316 moves to the closed position, the pressure of the brake fluid in the front brake caliper 148 ( FIG. 1 ) (whose fluid is coupled to the biasing cavity 320) is reduced. This reduction in pressure results in less braking force, which allows the front wheel 104 to rotate slightly faster, causing the rear wheel 106 ( FIG. 1 ) to drop back down onto the riding surface 110 ( FIG. 1 ), and, therefore, preventing a rollover event.

The spool valve 310 remains in the closed state until the rear wheel 106 (FIG. 1) again contacts the riding surface 110 (FIG. 1) or the rider releases the front brake actuator 200 (FIG. 1). For example, if the rear wheel 106 drops and contacts the riding surface 110 again, the rear wheel 106 begins to rotate. If the front brake actuator 200 is still actuated, the friction between the rear brake pads 1100, 1202 (FIGS. 12 and 13) and the rear brake disc 152 (FIG. 1) will again generate the biasing force, which moves the caliper housing 500 in the forward direction to the forward position (as shown in FIG. 17A). Thus, the stop 802 pushes the shuttle 316 back to the open position (left in FIGS. 18A and 18B ), thereby fluidly coupling the front brake actuator 200 and the front brake caliper 148 ( FIG. 1 ) again. Thus, movement of the caliper housing 500 causes a change in the state or flow characteristics of the check valve 310 (e.g., causing the check valve 310 to open). The shuttle 316 may alternate or oscillate between the open and closed positions as the rear wheel 106 alternates between contacting and lifting from the riding surface 110. This allows the rider to safely control the bicycle 100 during a rapid deceleration event.

If the rider releases the front brake actuator 200 while the shuttle 316 is in the closed position (the position shown in FIGS. 18A and 18B ), the pressure in the neutral cavity 318 decreases. As a result, the check valve 402 opens and allows the brake fluid to flow from the biasing cavity 320 to the neutral cavity 318 (and therefore, from the first port 304 to the second port 306), which relieves the pressure on the front brake caliper 148. Additionally, the rear braking force provided by the stop 802 (via the spring 622) on the shuttle 316 eventually overcomes the pressure from the neutral cavity 318 acting on the shuttle 316 and the shuttle 316 moves to the open position (left in FIGS. 18A and 18B ). When the shuttle 316 moves to the open position, the second spool 324 moves away from the seat 328, and the front brake actuator 200 and the front brake caliper 148 are fluidly coupled again. As the brake fluid flows back toward the front brake actuator 200, the pressure in the front brake caliper 148 is also reduced.

As seen between FIG. 17A and FIG. 18A , the articulation of the caliper housing 500 between the forward position and the rearward position is generally in a circular path along the rotating rear brake disc 152 ( FIG. 1 ) that is centered about the axis of the rear wheel 106. However, in other examples, the caliper housing 500 may be configured to articulate in a path that is not centered about the rear wheel axis. Instead, the caliper housing 500 may articulate (e.g., via an articulation mechanism 501 ( FIG. 5 )) on some other predetermined circular, non-circular, linear, or non-linear path. For example, the caliper housing 500 may articulate in a linear path on a linear slide. Also, although the rear brake caliper 154 in the illustrated example is disposed above or in a position covering the rear brake disc 152, in other examples, the rear brake caliper 154 may be disposed in any other position around the rear brake disc 152. For example, the rear brake caliper 154 may be disposed below or underneath the rear brake disc 152, disposed in front of the rear brake disc 152 (toward the forward direction of the bicycle 100), disposed behind the rear brake disc 152, etc. Additionally or alternatively, the front and rear swing arms 604, 614 may be eliminated. Alternatively, the clamp housing 500 and/or the bracket 502 may be coupled to the frame 102 and/or the rear wheel hub 124 in other configurations that may provide for articulation (e.g., circular articulation, linear articulation, etc.).

In the illustrated examples of FIGS. 5 to 18B , spring 622 is outside of spool valve 310. However, in other examples, a spring may be disposed within spool valve 310. For example, FIG. 19 illustrates an example in which a spring 1900 is disposed in chamber 314 of spool valve 310. In this example, spring 1900 is a tension spring. Spring 1900 biases shuttle 316 to the open position (left side of FIG. 19 ). In some examples, spring 1900 may be used in combination with spring 622 to provide a combined force. In other examples, only one spring may be used.

In yet other examples, no biasing or return spring may be employed. In this example, the shuttle 316 may remain stationary in the closed position (when the front brake actuator 200 is not actuated). However, when the front brake actuator 200 is actuated, the rear brake force (if present) moves the shuttle 316 to the open position to enable fluid to flow between the front brake actuator 200 and the front brake caliper 148.

In the examples described above with respect to FIGS. 3A to 19 , the spool valve 310 is configured as a normally open valve. However, in other examples, the spool valve 310 may be configured as a normally closed valve. FIGS. 20A to 20D are schematic diagrams of an exemplary valve and fluid path configuration, wherein a normally closed valve configuration is implemented with respect to the brake system 140. This valve configuration may be implemented in a similar manner with respect to the rear brake caliper 154 shown in FIGS. 5 to 19 .

FIG. 20A shows the state of the brake system 140 when both the front brake actuator 200 and the rear brake actuator 202 are not actuated. This may occur, for example, when the bicycle 100 ( FIG. 1 ) is at rest or in a free-rolling state. As shown in FIG. 20A , the shuttle 316 is in a closed position. The shuttle 316 is biased to the closed position (right in FIG. 20A ) by the spring 2000. Thus, in this example, the spool valve 310 is configured as a normally closed valve. In the example shown, the spring 2000 is a compression spring disposed in the valve housing 312. In other examples, other types of springs may be used and/or the spring(s) may be configured in other positions to bias the shuttle 316 to the closed position.

FIG20B shows the exemplary valve and fluid path configuration of FIG20A when the front brake actuator 200 is actuated and the rear wheel 106 (FIG. 1) rotates and maintains contact with the riding surface 110 (FIG. 1). As indicated by the arrows, when the front brake actuator 200 is actuated, the front brake actuator 200 pushes the brake fluid through the first port 304 and into the secondary slave piston chamber(s) 302 and the spool valve 310. The increased pressure in the slave piston chamber(s) 302 causes the rear brake pads 1100, 1202 (FIGS. 12 and 13) to engage the rear brake disc 152 (FIG. 1). If the rear wheel 106 is rotating (e.g., when the rear wheel 106 is in contact with the riding surface 110), the friction between the rear brake pads 1100, 1202 and the rear brake disc 152 biases the caliper housing 500 in the forward direction (FIG. 5). Therefore, a rear brake force is applied to the shuttle 316 to move the shuttle 316 to the open position, as indicated by the arrow. For example, as shown in FIGS. 17A and 17B, when the rear brake force is applied, the stop 802 biases the shuttle 316 to the open position (to the left in FIGS. 17A and 17B). In this example, the rear brake force is greater than the combined force of the spring 2000 and the pressure of the brake fluid in the neutral cavity 318 acting on the first spool 322. Thus, the shuttle 316 is moved to the open position. When the shuttle 316 is in the open position, the brake fluid is pushed through the neutral cavity 318, through the transfer path 330, through the biasing cavity 320, through the second port 306, and through the second fluid line 162 to the front brake caliper 148. In this way, braking pressure is applied to the front wheel 104 (Figure 1). Therefore, as long as the rear wheel 106 rotates (indicating contact with the riding surface 110), the frictional engagement provides sufficient force to maintain the spool valve 310 in the open state. This allows the brake fluid to flow back and forth between the front brake actuator 200 and the front brake caliper 148 as desired. Therefore, a rider can use the front brake actuator 200 to apply braking pressure to the front wheel 104 or relieve braking pressure from the front wheel 104.

FIG. 20C shows the exemplary valve and fluid passage configuration of FIGS. 20A and 20B when the front brake actuator 200 is actuated while the rear wheel 106 ( FIG. 1 ) is lifted from the riding surface 110 ( FIG. 1 ). As disclosed herein, when the rear wheel 106 is lifted from the riding surface 110, pressure from the rear brake pads 1100, 1202 ( FIGS. 12 and 13 ) stops the rear brake disc 152 and the rear wheel 106. This can occur relatively quickly because there is no friction from the riding surface 110 rotating the rear wheel 106. Once the rear wheel 106 stops rotating, the rear brake force ( FIG. 20B ) applied to the shuttle 316 also ceases. The combined force from spring 2000 and the pressure of the brake fluid in the neutral cavity 318 moves the shuttle 316 to the closed position (to the right in FIG. 20C ).

When the shuttle 316 is in the closed position, the first port 304 is isolated or fluidly disconnected from the second port 306, and therefore, the front brake actuator 200 is disconnected from the front brake caliper 148. Therefore, the front brake actuator 200 cannot apply more pressure to the front brake caliper 148. The brake fluid in the second port 306, the second fluid line 162, and the front brake caliper 148 flows in the opposite direction (back toward the spool valve 310) and reduces pressure. This is due to the expansion of the biasing cavity 320 and the disconnection from the first port 304 (which previously supplied the brake fluid flow). The reduction in pressure reduces or relieves the braking pressure at the front brake caliper 148. As a result, the front wheel 104 (FIG. 1) can move faster, which reduces the amount of forward tilt and allows the rear wheel 106 to move back down onto the riding surface 110. Once the rear wheel 106 contacts the riding surface 110 and begins to rotate again, the rear braking force is again applied to the shuttle 316 (see FIG. 20B), which moves the shuttle 316 back to the open position (left side of FIG. 20C). Similar to the valve configuration disclosed with respect to FIGS. 3A-3D, the spool valve 310 in this configuration can oscillate or alternate between the open and closed states as the rear wheel 106 lifts up and down from the riding surface 110.

As shown in FIG20D, when the front brake actuator 200 is released to relieve the brake pressure, the brake fluid in the first port 304 and the first fluid line 160 flows back toward the front brake actuator 200. As a result, the frictional engagement between the rear brake pads 1100, 1202 (FIGS. 12 and 13) and the rear brake disc 152 (FIG. 1) is reduced and/or discontinued. In addition, the pressure in the neutral cavity 318 of the spool valve 310 is reduced. Once the pressure in the neutral cavity 318 is reduced by a sufficient amount, the force from the spring 2000 pushes the shuttle 316 to the closed position, as shown in FIG20D.

In the example shown in FIGS. 20A to 20D , the rear brake caliper 154 includes a bypass passage 400 and a check valve 402 (see FIG. 20D ) that allow the brake fluid to flow from the second port 306 to the first port 304 to more quickly relieve or reduce the brake pressure. Thus, when the front brake actuator 200 is released, the brake fluid moves from the front brake caliper 148 toward the front brake actuator 200, as shown by the arrows. However, in other examples, the bypass passage 400 and the check valve 402 may not be included. Similar to the above example, the rear brake actuator 202 can be used to independently actuate the rear brake caliper 154.

In the exemplary configurations shown in FIGS. 3A-4 (normally open) and 20A-20D (normally closed), the secondary slave piston chamber 302 is fluidly coupled to the first port 304 (e.g., upstream from the spool valve 310). Thus, actuation or release of the front brake actuator 200 directly affects the pressure in the secondary slave piston chamber 302, regardless of whether the spool valve 310 is open or closed. In other examples, the rear brake caliper 154 can be configured such that the secondary slave piston chamber(s) 302 are fluidly coupled to the second port 306 (e.g., downstream from the spool valve 310). 21A-21D are schematic diagrams of an exemplary valve and fluid passage configuration implemented with respect to the brake system 140, wherein the secondary slave piston chamber(s) 302 are implemented in fluid coupling with the second port 306. This valve configuration may be implemented in a similar manner with respect to the rear brake caliper 154 shown in FIGS. 5-19.

FIG. 21A illustrates the state of the brake system 140 when both the front brake actuator 200 and the rear brake actuator 202 are not actuated. In this example, the spool valve 310 is configured as a normally open valve. Therefore, the spool valve 310 operates substantially as described above with respect to FIGS. 3A to 3D. In FIG. 21A, the shuttle 316 is in the open position. The first port 304 fluidly couples the first fluid line 160 to the neutral cavity 318 of the spool valve 310. In this example, the secondary slave piston chamber 302 is fluidly coupled to the second port 306.

21B shows the exemplary valve and fluid path configuration of FIG. 20A ( FIG. 1 ) when the front brake actuator 200 is actuated and the rear wheel 106 ( FIG. 1 ) is rotating and maintaining contact with the riding surface 110. As indicated by the arrows, when the front brake actuator 200 is actuated, the front brake actuator 200 pushes the brake fluid through the first port 304 and into the spool valve 310. The brake fluid is pushed through the neutral cavity 318, through the transfer path 330, through the biasing cavity 320, through the second port 306, and through the second fluid line 162 to the front brake caliper 142. The brake fluid also flows from the second port 306 into the secondary slave piston chamber(s) 302, which causes the rear brake pads 1100, 1202 (FIGS. 12 and 13) to engage the rear brake disc 152 (FIG. 1). If the rear wheel 106 is rotating (e.g., when the rear wheel 106 is in contact with the riding surface 110), the friction between the rear brake pads 1100, 1202 and the rear brake disc 152 biases the caliper housing 500 (FIG. 5) in a forward direction. Thus, a rear braking force is applied to the shuttle 316 to move the shuttle 316 to the open position, as indicated by the arrow. For example, as shown in FIGS. 17A and 17B , when a rear brake force is applied, the stop 802 biases the shuttle 316 to the open position (to the left in FIGS. 17A and 17B ). In this example, the combined force of the rear brake force and the spring 332 acting on the shuttle 316 is greater than the force from the pressure of the brake fluid in the neutral cavity 318. Thus, the shuttle 316 remains in the open position. Thus, as long as the rear wheel 106 rotates (which indicates contact with the riding surface 110), the frictional engagement provides sufficient force to keep the spool valve 310 in the open state. This allows the brake fluid to flow back and forth between the front brake actuator 200 and the front brake caliper 148 as desired.

FIG. 21C shows the exemplary valve and fluid path configuration of FIGS. 21A and 21B when the front brake actuator 200 is actuated while the rear wheel 106 ( FIG. 1 ) is lifted from the riding surface 110 ( FIG. 1 ). As disclosed herein, when the rear wheel 106 is lifted from the riding surface 110, pressure from the rear brake pads 1100, 1202 ( FIGS. 12 and 13 ) stops the rear brake disc 152 and the rear wheel 106. Once the rear wheel 106 stops rotating, the rear brake force ( FIG. 21B ) applied to the shuttle 316 ceases. The force from the pressure in the neutral cavity 318 overcomes the force from the spring 332 and moves the shuttle to the closed position (to the right in FIG. 21C ).

When the shuttle 316 is in the closed position, the first port 304 is isolated or fluidly disconnected from the second port 306, and therefore, the front brake actuator 200 is disconnected from the front brake caliper 148. Therefore, the front brake actuator 200 cannot apply more pressure to the front brake caliper 148. The brake fluid in the second port 306, the second fluid line 162, and the front brake caliper 148 flows in the opposite direction (back toward the spool valve 310) and reduces pressure. This reduces or relieves the brake pressure at the front brake caliper 148. As a result, the front wheel 104 (FIG. 1) can move faster, which reduces the amount of front caster and allows the rear wheel 106 to move back down onto the riding surface 110. Additionally, the pressure of the brake fluid in the slave piston chamber(s) 302 is slightly reduced. However, sufficient pressure is still maintained so that the rear brake pads 1100, 1202 (FIGS. 12 and 13) remain engaged with the rear brake disc 152 (FIG. 1).

If the rear wheel 106 contacts the riding surface 110 again and begins to rotate, the rear brake force is again applied to the shuttle 316 (as shown in FIG. 21B ), which causes the shuttle 316 to move to the open position (to the left in FIG. 21C ). Similar to the valve configurations disclosed with respect to FIGS. 3A to 3D and 20A to 20D , the spool valve 310 in this configuration may oscillate or alternate between the open and closed states as the rear wheel 106 is lifted up and down from the riding surface 110.

As shown in FIG. 21D , when the front brake actuator 200 is released to relieve the brake pressure, the brake fluid in the first port 304 and the first fluid line 160 moves back toward the front brake actuator 200, as shown in FIG. 20D . In the illustrated example, the rear brake caliper 154 includes a bypass passage 400 and a check valve 402 that allow the brake fluid to flow from the second port 306 to the first port 304 to relieve or reduce the brake pressure. Therefore, the brake fluid in the second port 306 flows back toward the first port 304, thereby releasing the brake pressure applied to the front wheel 104 and the rear wheel 106. In other examples, the bypass passage 400 and the check valve 402 may not be included. Once the pressure in the neutral cavity 318 is reduced by a sufficient amount, the force from the spring 332 pushes the shuttle 316 to the open position shown in Figure 21D. Once the shuttle 316 is open, the brake fluid can also flow through the transfer path 330 back to the first port 304. Similar to the example disclosed above, the rear brake actuator 202 can be used to independently actuate the rear brake caliper 154.

As described above, with this exemplary configuration, when the spool valve 310 is closed, the pressure in the secondary slave piston chamber 302 is slightly reduced. Therefore, when the rear wheel 106 drops back onto the riding surface 110, less braking pressure is applied to the rear wheel 106, which results in less sudden shock when the rear wheel 106 contacts the riding surface 110. In other words, the rear wheel 106 will begin to rotate faster again than in other configurations where a higher braking pressure is maintained in the secondary slave piston chamber 302 when the front brake actuator 202 is actuated.

Figures 22A, 22B, 23A and 23B illustrate an exemplary physical implementation of a brake system 140 having the exemplary valve and fluid passage configurations illustrated in the schematic diagrams of Figures 21A to 21D. Figure 22A is a cross-sectional view of an exemplary rear brake caliper 154 taken along a line similar to F-F shown in Figure 15. Figure 22B is an enlarged view of the reference 2200 in Figure 22A. In this example, the first and second ports 304, 306 have been swapped compared to the physical implementations of Figures 5 to 19. For example, the first port 304 is formed by a first bore 2202 formed in the valve housing 312 and fluidly coupled to the neutral cavity 318 of the spool valve 310. The first hollow bolt 700 is threadedly inserted into the first bore 2202 so that the first fluid line 160 is fluidly coupled to the neutral cavity 318 of the spool valve. In this example, the second spool 324 of the shuttle 316 is larger (e.g., wider and/or longer) than the spool valve 316 in other examples. In some examples, the longer shuttle 316 is easier to install than the shorter shuttle 316. In addition, in this example, the rear brake caliper 154 is shown without the bypass passage 400 and the check valve 402. However, in other examples, the rear brake caliper 154 may be provided with a check valve, similar to the exemplary implementations shown in FIGS. 17B and 18B .

FIG. 23A is a cross-sectional view of the rear brake caliper 154 taken along a line similar to that shown in FIG. 14A , E-E. FIG. 23B is an enlarged view of the reference 2300 in FIG. 23A . In this example, the second port 306 is formed by a second inner bore 2302 formed in the caliper housing 500 and a passage 2304 extending from the second inner bore 2302 to the biasing cavity 320 of the spool valve 310. The second hollow bolt 704 is threadedly inserted into the second inner bore 2302. In addition, similar to the first passage 1308 and the second passage 1310 shown in FIG. 13 , additional passages fluidly couple the second inner bore 2302 to the first and second secondary piston chambers 302a, 302b. Thus, in this example, the secondary slave piston chamber(s) 302 are fluidly coupled to the second port 306 (eg, downstream of the spool valve 310).

As can be appreciated from the foregoing, the above-described braking systems and devices reduce the likelihood of or prevent a rollover event caused by excessive braking on the front wheel of a bicycle. Thus, the exemplary braking systems and devices provide better control of the bicycle and improve safety for the rider. The exemplary braking systems and methods achieve this result without electronic components as seen in known anti-rollover systems. Furthermore, the exemplary braking systems and methods still provide independent control of the front and rear brakes.

From the above discussion, it will be understood that the present invention can be embodied in a variety of embodiments, including but not limited to the following:

Embodiment 1: A rear brake caliper for a bicycle, the rear brake caliper comprising: A caliper housing for coupling to the bicycle, the caliper housing comprising: A first port for fluid coupling to a first fluid circuit, the first fluid circuit being fluid coupled to a front brake actuator; and A second port for fluid coupling to a second fluid circuit, the second fluid circuit being fluid coupled to a front brake caliper; and A valve between the first port and the second port, the valve being operable to affect fluid flow between the first port and the second port.

Embodiment 2: The rear brake caliper of embodiment 1 further comprises a hinge mechanism, and the caliper housing is used to be coupled to the bicycle via the hinge mechanism.

Embodiment 3: A rear brake caliper as in Embodiment 2, wherein the hinge mechanism comprises a bracket, and wherein the caliper housing is movable between a forward position and a rearward position relative to the bracket.

Embodiment 4: A rear brake caliper as in Embodiment 3, further comprising: a stop engaged with a flow control member of the valve, the flow control member being movable between an open position and a closed position, wherein in the open position, the first port is fluidly coupled to the second port, and in the closed position, the first port is isolated from the second port.

Embodiment 5: A rear brake caliper as in Embodiment 4, further comprising a rear brake pad, wherein, when the front brake actuator is actuated and a rear wheel of the bicycle contacts a riding surface, the caliper housing is biased toward the forward position via frictional engagement between the rear brake pad and a rear brake disc, biasing the stop against the flow control member to maintain the flow control member in the open position.

Embodiment 6: A rear brake caliper as in Embodiment 5, wherein when the front brake actuator is actuated and the rear wheel is not in contact with the riding surface, the flow control member moves to the closed position, which moves the stop and causes the caliper housing to move toward the rearward position.

Embodiment 7: The rear brake caliper of Embodiment 3 further comprises a spring coupled between the bracket and the caliper housing, the spring being used to bias the caliper housing toward the forward position.

Embodiment 8: A rear brake caliper as in Embodiment 3, wherein movement of the caliper housing relative to the bracket causes a change in a state of the valve.

Embodiment 9: The rear brake caliper as in Embodiment 1 further includes a rear brake pad, wherein the caliper housing includes a secondary piston chamber having a secondary piston, the secondary piston is coupled to the rear brake pad, and the second port is coupled to the secondary piston chamber fluid, so that when the front brake actuator is actuated, the brake fluid is supplied to the secondary piston chamber to move the rear brake pad into engagement with a rear brake disc.

Embodiment 10: A rear brake caliper as in Embodiment 9, wherein the caliper housing comprises: a primary piston chamber having a primary piston coupled to the rear brake pad, the primary piston chamber being isolated from the secondary piston chamber; and a third port for fluid coupling to a third fluid line, the third fluid line being fluid coupled to a rear brake actuator, the third port being fluid coupled to the primary piston chamber, so that actuation of the rear brake actuator supplies brake fluid to the primary piston chamber to move the rear brake pad into engagement with the rear brake disc.

Embodiment 11: The rear brake caliper of Embodiment 1 further comprises: a bypass passage whose fluid couples the first port and the second port; and a check valve for preventing the fluid from flowing from the first port through the bypass passage to the second port.

Embodiment 12: A brake system for a bicycle, the brake system comprising: a front brake actuator; a front brake caliper; a rear brake actuator; a rear brake caliper; a first fluid circuit coupled between the front brake actuator and the rear brake caliper; a second fluid circuit coupled between the rear brake caliper and the front brake caliper; and A third fluid circuit coupled between the rear brake actuator and the rear brake caliper, wherein actuation of the front brake actuator supplies a first brake fluid to the front brake caliper through the first fluid circuit, the rear brake caliper, and the second fluid circuit to actuate the front brake caliper to apply brake pressure to a front wheel of the bicycle, and wherein actuation of the rear brake actuator supplies a second brake fluid to the rear brake caliper to apply brake pressure to a rear wheel of the bicycle without actuating the front brake caliper.

Embodiment 13: A brake system as in Embodiment 12, wherein the rear brake caliper comprises: a caliper housing, the caliper housing comprising: a first port, the first fluid line fluidically coupled to the first port; and a second port, the second fluid line fluidically coupled to the second port; and a valve, between the first port and the second port, the valve operable between an open state and a closed state, the open state allowing the first brake fluid to move through the valve between the front brake caliper and the front brake actuator, and the closed state fluidically disconnecting the front brake caliper from the front brake actuator.

Embodiment 14: A brake system as in Embodiment 13, wherein the caliper housing includes a secondary piston chamber, the first port fluid is coupled to the secondary piston chamber, so that actuation of the front brake actuator supplies the first brake fluid to the secondary piston chamber to actuate the rear brake caliper to apply braking pressure to the rear wheel.

Embodiment 15: A brake system as in Embodiment 14, wherein, if the rear wheel is in contact with a riding surface, the valve is maintained in the open state to allow the first brake fluid to be supplied by the front brake actuator to the front brake caliper to apply braking pressure to the front wheel of the bicycle, and, if the rear wheel is not in contact with the riding surface, the valve moves to the closed state to relieve the pressure from the front brake caliper.

Embodiment 16: A brake system as in Embodiment 14, wherein the caliper housing comprises: a primary piston chamber isolated from the secondary piston chamber; and a third port, the third port fluid coupled between the third fluid line and the primary piston chamber, so that actuation of the rear brake actuator supplies the secondary brake fluid to the primary piston chamber to actuate the rear brake caliper to apply braking pressure to the rear wheel.

Embodiment 17: A brake system as in Embodiment 16, wherein the primary piston chamber has a larger diameter than the secondary piston chamber.

Embodiment 18: A brake system as in Embodiment 16, wherein the caliper housing isolates the third port from the first and second ports.

Embodiment 19: A rear brake caliper for a bicycle, the rear brake caliper comprising: A caliper housing, which is used to couple to the bicycle and close to a rear wheel of the bicycle, the caliper housing comprising: A first port, which is used to fluidly couple to a first fluid circuit, the first fluid circuit is fluidly coupled to a first master piston chamber; A second port, which is used to fluidly couple to a second fluid circuit, the second fluid circuit is fluidly coupled to a front brake caliper; A third port, which is used to fluidly couple to a third fluid circuit, the third fluid circuit is fluidly coupled to a second master piston chamber; a main slave piston chamber, the third port fluid is coupled to the main slave piston chamber, so that the pressurization of the brake fluid in the second master piston chamber increases the pressure in the main slave piston chamber to actuate the rear brake caliper; and a secondary slave piston chamber, which is isolated from the main slave piston chamber, the first port fluid is coupled to the secondary slave piston chamber, so that the pressurization of the brake fluid in the first master piston chamber increases the pressure in the secondary slave piston chamber to actuate the rear brake caliper.

Embodiment 20: A rear brake caliper as in Embodiment 19, further comprising a valve between the first port and the second port, the valve being operable between an open state and a closed state, wherein in the open state, the first port is fluidly coupled to the second port, and in the closed state, the first port is isolated from the second port.

The illustrations of the embodiments described herein are intended to provide a general understanding of the structures of the various embodiments. The illustrations are not intended to serve as a complete description of all elements and features of apparatus and systems utilizing the structures or methods described herein. Many other embodiments may become apparent to one skilled in the art after reviewing the present invention. Other embodiments may be utilized and derived from the present invention, allowing structural and logical substitutions and changes without departing from the scope of the present invention. Furthermore, the illustrations are representative only and may not be drawn to scale. Certain proportions in the illustrations may be exaggerated, while other proportions may be reduced. Therefore, the present invention and the drawings are to be considered illustrative and not restrictive.

Although this specification contains many details, these details should not be construed as limitations on the scope of the invention or what may be claimed, but rather as detailed descriptions of features of particular embodiments of the invention. Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination. Furthermore, while features may function in certain combinations as described above and even as originally claimed, one or more features from a claimed combination may be deleted from that combination in some cases, and a claimed combination may refer to subcombinations or variations of subcombinations.

Although specific embodiments have been illustrated and described herein, it should be understood that any subsequent configuration designed to achieve the same or similar purpose may replace the specific embodiments shown. The present invention is intended to cover any and all subsequent adaptations or variations of the various embodiments. Combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art after reviewing the specification.

The Abstract is provided to comply with 37 C.F.R. § 1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the preceding detailed description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intent that the claimed embodiments require more features than expressly recited in each claim. Rather, as reflected in the claims below, subject matter may refer to less than all of the features of any of the disclosed embodiments. Accordingly, the claims below are incorporated into the detailed description, with each claim serving by itself to individually define claimed subject matter.

The foregoing detailed description is intended to be illustrative rather than restrictive and it should be understood that the following claims, including all equivalents, are intended to define the scope of the invention. The claims should not be considered limited to the described order or elements unless stated to that effect. Therefore, all embodiments and their equivalents within the scope and spirit of the following claims are claimed by the present invention.

100: bicycle 102: frame 104: front wheel 106: rear wheel 108: front fork 110: riding surface 112: seat 114: seat post 116: handlebars 118: drive train 120: crank assembly 122: chain 124: rear wheel hub 126: crank arm 128: pedals 130: front sprocket or chain ring 140: brake system 142: front brake 144: rear brake 146: front brake disc 148: front brake caliper 150: front wheel hub 152: rear brake disc 154: Rear brake caliper 160: First fluid circuit 162: Second fluid circuit 164: Third fluid circuit 200: Front brake actuator 202: Rear brake actuator 204: Front brake lever 206: Rear brake lever 208: First master piston chamber 210: First master piston 212: Second master piston chamber 214: Second master piston 300: Primary slave piston chamber 300a: First primary piston chamber 300b: Second primary piston chamber 302: Secondary slave piston chamber 302a: First secondary piston chamber 302b: Second secondary piston chamber 304: First port 306: Second port 308: Third port 310: Valve 312: Valve housing 314: Chamber 316: Shuttle 318: First cavity or neutral cavity 320: Second cavity or biasing cavity 322: First spool 324: Second spool 326: Stem 328: Seat 330: Transmission path 332, 622: Spring 400: Bypass passage 402: Check valve 500: Clamp housing 501: Hinge mechanism 502: Bracket 504, 506: Fastener 600, 602: Front end 604: Front swing arm 606, 616: First pin 608, 618: Second pin 610, 612: Rear end 614: rear swing arm 700: first hollow bolt 702: first joint 704: second hollow bolt 706: second joint 708: third hollow bolt 710: third joint 800: first stop or buffer 802: stop 1000: first main piston 1002: first secondary piston 1100: brake pad 1102: pin 1200: second main piston 1202: second rear brake pad 1204: third inner hole 1206, 1304, 1502: internal channel 1208, 1306, 1404, 1504, 1600: opening 1210, 1308: first passage 1212, 1310: Second passageway 1300: Second secondary piston 1302, 2202: First inner hole 1400: Third passageway 1402, 1700, 1800, 2200, 2300: Marking 1500, 2302: Second inner hole 1702: Inner wall 1704: Seal assembly 1706, 1712: Pressure cap 1708: First O-ring 1710: First fastener 1714: Second O-ring 1716: Second fastener 1718: First opening 1720: Second opening 1722: Ball 1724, 1900, 2000: Spring 1726: Seal 1728: First assembly 1730: Second component 1802: Second stop or buffer 2304: Passage A: Forward direction of movement COG: Center of gravity

FIG. 1 is a side view of an exemplary bicycle that may employ an exemplary brake system constructed in accordance with the teachings of the present invention.

FIG. 2 is an enlarged view of the exemplary components of the exemplary brake system of FIG. 1 implemented on a exemplary bicycle.

Fig. 3A is a schematic diagram of an exemplary valve and fluid path configuration that may be implemented in the exemplary brake system of Figs. 1 and 2. Fig. 3A shows the exemplary brake system during a state in which the brake actuator is not actuated.

FIG. 3B shows the schematic diagram of FIG. 3A when a front brake actuator is actuated and a rear wheel of the exemplary bicycle is in contact with a riding surface.

FIG. 3C shows the schematic diagram of FIGS. 3A and 3B when the front brake actuator is actuated and the rear wheel of the bicycle is not in contact with the riding surface.

FIG. 3D shows a schematic diagram of FIGS. 3A to 3C when the front brake actuator is released.

FIG. 4 shows a schematic diagram of an exemplary bypass passage and a check valve as shown in FIGS. 3A to 3D that may be implemented with respect to the exemplary brake system.

5 is a side view of an exemplary rear brake caliper of the exemplary brake system of FIG. 2 implemented in the exemplary configuration shown in the schematic diagrams of FIGS. 3A to 4 .

6 and 7 are perspective views of the exemplary rear brake caliper of FIG. 5 .

8 and 9 are side views of the exemplary rear brake caliper of FIG. 5 .

FIG. 10 is a cross-sectional view of the exemplary rear brake caliper taken along line A-A of FIG. 6 .

FIG. 11 is a cross-sectional view of the exemplary rear brake caliper taken along line B-B of FIG. 6 .

FIG. 12 is a cross-sectional view of the exemplary rear brake caliper taken along line C-C of FIG. 7 .

FIG. 13 is a cross-sectional view of the exemplary rear brake caliper taken along line D-D of FIG. 7 .

FIG. 14A is a cross-sectional view of the exemplary rear brake caliper taken along line E-E of FIG. 6 .

FIG. 14B is an enlarged view of the annotations in FIG. 14A .

FIG. 15 is a cross-sectional view of the exemplary rear brake caliper taken along line F-F of FIG. 6 .

FIG. 16 is a cross-sectional view of the exemplary rear brake caliper taken along line G-G of FIG. 7 .

Fig. 17A is a cross-sectional view of the exemplary brake caliper taken along line H-H of Fig. 6. Fig. 17A shows an example of the rear brake caliper when a front brake actuator of the exemplary brake system is actuated and a rear wheel of the exemplary bicycle is in contact with a riding surface.

FIG. 17B is an enlarged view of the callout in FIG. 17A showing the demonstration valve in the open position.

FIG. 18A shows the exemplary rear brake caliper of FIG. 17A when the front brake actuator is actuated and the rear wheel is not in contact with the riding surface.

FIG. 18B is an enlarged view of the callout in FIG. 18B showing the demonstration valve in the closed position.

FIG. 19 illustrates an example of the rear brake actuator of FIG. 17A with an additional or alternative spring configuration.

Fig. 20A is a schematic diagram of another exemplary valve and fluid passage configuration that may be implemented in the exemplary brake system of Figs. 1 and 2. Fig. 20A shows the exemplary brake system during a state in which the brake actuator is not actuated.

FIG. 20B shows the schematic diagram of FIG. 20A when a front brake actuator is actuated and a rear wheel of the exemplary bicycle is in contact with a riding surface.

FIG. 20C shows the schematic diagram of FIGS. 20A and 20B when the front brake actuator is actuated and the rear wheel of the demonstration bicycle is not in contact with the riding surface.

FIG. 20D shows a schematic diagram of FIGS. 20A to 20C when the front brake actuator is released.

Fig. 21A is a schematic diagram of another exemplary valve and fluid passage configuration that may be implemented in the exemplary brake system of Figs. 1 and 2. Fig. 21A shows the exemplary brake system during a state in which the brake actuator is not actuated.

FIG. 21B shows the schematic diagram of FIG. 21A when a front brake actuator is actuated and a rear wheel of the exemplary bicycle is in contact with a riding surface.

FIG. 21C shows the schematic diagram of FIGS. 21A and 21B when the front brake actuator is actuated and the rear wheel of the demonstration bicycle is not in contact with the riding surface.

Figure 21D shows a schematic diagram of Figures 21A to 21C when the front brake actuator is released.

22A is a cross-sectional view of an exemplary rear brake caliper of the exemplary brake system of FIGS. 1 and 2 implemented in the exemplary configuration shown in the schematic diagrams of FIGS. 21A to 21D .

FIG. 22B is an enlarged view of the annotations in FIG. 22A .

FIG. 23A is another cross-sectional view of the exemplary rear brake caliper of FIG. 22A implemented in the exemplary configuration shown in the schematic diagrams of FIGS. 21A to 21D .

FIG. 23B is an enlarged view of the annotations in FIG. 22A .

The drawings are not drawn to scale. Instead, the thickness of the layers or regions are exaggerated in the drawings. In general, the same symbols are used in the drawings and the accompanying text description to indicate the same or similar components.

When identifying multiple elements or components that can be referred to separately, descriptors such as "first", "second", and "third" are used herein. Unless otherwise specified or understood based on the context of their use, these descriptors are not intended to have any priority or ordering meaning in time, but are only intended to be used as marks for referring to multiple elements or components separately to facilitate understanding of the disclosed examples. In some examples, the descriptor "first" can be used to refer to an element in the detailed description, while the same element can be referred to by different descriptors such as "second" or "third" in a claim. In this case, it should be understood that these descriptors are only for easy reference to multiple elements or components.

116:Handle

140: Braking system

148:Front brake caliper

154:Rear brake caliper

160: First fluid line

162: Second fluid circuit

164: Third fluid line

200:Front brake actuator

202: Rear brake actuator

204:Front brake lever

206:Rear brake lever

208: First main piston chamber

210: First main piston

212: Second main piston chamber

214: Second main piston

Claims (15)

A rear brake caliper for a bicycle, the rear brake caliper comprising: a caliper housing for coupling to the bicycle, the caliper housing including: a port for fluid coupling to a fluid line, the fluid line fluid coupling to a second brake caliper; and a valve configured to control the flow of fluid between the port and the front brake, wherein movement of the caliper housing causes a change in the state of the valve. The rear brake caliper of claim 1 further comprises a hinge mechanism, wherein the caliper housing is coupled to the bicycle via the hinge mechanism, wherein the hinge mechanism facilitates the movement of the caliper housing. A rear brake caliper as claimed in claim 2, wherein the hinge mechanism includes a bracket, and wherein the caliper housing is movable between a forward position and a rearward position relative to the bracket. The rear brake caliper of claim 3 further comprises a stopper engaged with a flow control member of the valve, the flow control member being movable between an open position and a closed position, in which the port is fluidly coupled to the second caliper and in which the port is isolated from the second caliper. A rear brake caliper as claimed in claim 4, further comprising a rear brake pad, wherein, when a front brake actuator is actuated and a rear wheel of the bicycle contacts a riding surface, the caliper housing is biased toward the forward position via frictional engagement between the rear brake pad and a rear brake disc, biasing the stop against the flow control member to maintain the flow control member in the open position. A rear brake caliper as claimed in claim 5, wherein when the front brake actuator is actuated and the rear wheel is not in contact with the riding surface, the flow control member moves to the closed position, which moves the stop and causes the caliper housing to move toward the rearward position. The rear brake caliper of claim 3 further comprises a spring coupled between the bracket and the caliper housing, the spring being used to bias the caliper housing toward the forward position. A rear brake caliper as claimed in claim 1, further comprising a rear brake pad, wherein the caliper housing comprises a secondary piston chamber having a secondary piston, the secondary piston being coupled to the rear brake pad, and a second port of fluid being coupled to the secondary piston chamber, so that when a front brake actuator is actuated, brake fluid is supplied to the secondary piston chamber to move the rear brake pad into engagement with a rear brake disc. A rear brake caliper as claimed in claim 8, wherein the caliper housing comprises: a primary piston chamber having a primary piston coupled to the rear brake pad, the primary piston chamber being isolated from the secondary piston chamber; and a third port for fluid coupling to a third fluid line, the third fluid line being fluid coupled to a rear brake actuator, the third port being fluid coupled to the primary piston chamber, so that actuation of the rear brake actuator supplies brake fluid to the primary piston chamber to move the rear brake pad into engagement with the rear brake disc. A rear brake caliper as claimed in claim 1, wherein the movement is caused by an interaction between the rear brake caliper and a brake disc. A rear brake caliper as claimed in claim 1, wherein the movement is a first movement and a second movement causes a second change in the state of the valve. A rear brake caliper as claimed in claim 1, wherein the first movement and the second movement are in opposite directions. A brake system for a bicycle, the brake system comprising: a front brake actuator; a front brake caliper; a rear brake actuator; a rear brake caliper; a first fluid circuit coupled between the front brake actuator and the rear brake caliper; a second fluid circuit coupled between the rear brake caliper and the front brake caliper; wherein the rear brake caliper includes a valve configured to control the fluid flow of the second fluid. A brake system as claimed in claim 13, wherein movement of a housing of the rear brake caliper causes a change in the state of the valve. The brake system of claim 14 further comprises a third fluid circuit coupled between the rear brake actuator and the rear brake caliper.