Hydraulic disc brake lever assembly

Abstract

Claims

2. The brake lever assembly of claim 1, wherein the master piston has a non-actuated state and a seal, the master cylinder has a port, and the dead band is the distance between the seal and the port when the master piston is in the non-actuated state.

3. The brake lever assembly of claim 1, wherein the lever has a shaft and an adjustable connector disposed through the shaft, and moving the adjustable connector with respect to the shaft adjusts the dead band.

4. The brake lever assembly of claim 1, wherein the lever has a neutral position and a fully actuated position defining a reach between the neutral position and the fully-actuated position, and the reach is adjustable.

5. The brake lever assembly of claim 1, wherein the master cylinder has a longitudinal axis, and the pivot axis is spaced apart from the longitudinal axis.

6. The brake lever assembly of claim 5, wherein the position of the pivot axis with respect to the housing is adjustable in a direction that is substantially parallel to the master cylinder's longitudinal axis.

7. The brake lever assembly of claim 1, wherein the housing further comprises a pair of opposing slots, the lever includes a pivot shaft, the pivot shaft has a longitudinal axis defining the pivot axis, and the pivot shaft is movably disposed within the pair of opposing slots.

8. An brake lever assembly, comprising: a housing; a master cylinder assembly disposed in the housing and comprising a master piston, the master cylinder assembly having an adjustable dead band; a lever connected to the housing and having a reach; wherein the lever is pivotable about a first pivot axis to adjust the reach, and the lever is pivotable about a second pivot axis to actuate the master piston.

9. The brake lever assembly of claim 8, wherein the master piston has a non-actuated state and a seal, the master cylinder has a port, and the dead band is the distance between the seal and the port when the master piston is in the non-actuated state.

10. The brake lever assembly of claim 8, wherein the lever has a neutral position and a fully-actuated position, and the reach is the distance between the neutral position and the fully-actuated position.

11. The brake lever assembly of claim 8, wherein the reach is adjustable independently of the dead band.

12. The brake lever assembly of claim 8, wherein the dead band is adjustable independently of the reach.

13. The brake lever assembly of claim 8, wherein the lever has a first pivot shaft defining the first pivot axis and a second pivot shaft defining the second pivot axis, and the first pivot shaft is spaced apart from the second pivot shaft.

14. The brake lever assembly of claim 8, wherein the lever comprises a pivot shaft defining the second pivot axis, and the second pivot shaft is operatively connected to the master piston.

15. The brake lever assembly of claim 14, further comprising an adjustable connector disposed through the pivot shaft and operatively connected to the master piston, wherein moving the adjustable connector with respect to the pivot shaft adjusts the dead band.

16. An brake lever assembly, comprising: a housing having first and second pairs of opposing slots, wherein the first and second pairs of opposing slots are spaced apart from one another; a lever having a first pivot shaft and a second pivot shaft, the first pivot shaft being disposed in the first pair of opposing slots and having a position in the first pair of slots, the second pivot shaft being disposed in the second pair of opposing slots; a master cylinder disposed in the housing; a master piston disposed in the master cylinder; a dead band adjustment device operatively connecting the master piston to the second pivot shaft, wherein the dead band adjustment device is adjustable to vary the position of the master piston with respect to the second pivot shaft; and a reach adjustment device connecting the housing to the first pivot shaft, wherein the reach adjustment device is adjustable to vary the position of the first pivot shaft in the first pair of opposing slots.

17. The brake lever assembly of claim 16, wherein the lever has a neutral position and a fully-actuated position defining a reach between the neutral position and the fully actuated position, and adjusting the position of the first pivot shaft in the first pair of opposing slots adjusts the reach.

18. A method of adjusting the reach of a brake lever assembly, wherein the brake lever assembly includes a lever operatively connected to a master cylinder assembly, the lever has a neutral position, and the master cylinder assembly has a dead band that is adjustable without varying the lever's neutral position, the method comprising: pivoting the lever about a lever region that is substantially aligned with the master cylinder assembly.

19. The method of claim 18, wherein the master cylinder assembly has a longitudinal axis, and the lever region defines a pivot axis that is substantially perpendicular to the master cylinder assembly's longitudinal axis.

20. A brake lever assembly, comprising: a master cylinder assembly having a dead band and comprising a master piston disposed in a master cylinder; a lever operatively connected to the master piston; and means for adjusting the dead band.

21. A brake lever assembly, comprising: a housing having a pair of opposing slots; a master cylinder disposed in the housing and having a port; a master piston assembly disposed in the master cylinder, the master piston assembly comprising a master piston, the master piston having a seal, the master piston further having a non-actuated state defining a distance between the seal and the port when the master piston is in the non-actuated state; a lever having a first end and a cross member, wherein the first end is pivotally connected to the housing, and the cross member is spaced apart from the first end and disposed in the pair of opposing slots; and an adjustable connector operatively connecting the cross member to the master piston assembly, wherein the adjustable connector is adjustable to vary the distance.

22. The brake lever of claim 21, wherein the adjustable connector abuttingly engages the master piston assembly.

23. The brake lever assembly of claim 21, wherein the master piston is biased towards the lever.

24. The brake lever assembly of claim 21, wherein the adjustable connector is rotatable to vary the position of the adjustable connector with respect to the lever.

25. The brake lever assembly of claim 21, further comprising a first coupling member, wherein the adjustable connector has an adjustment end and an engagement end, the engagement end is connected to the first coupling member, and the first coupling member abuttingly engages the master piston assembly.

26. The brake lever assembly of claim 25, wherein the master piston assembly further comprises a second coupling member attached to the master piston, and the second coupling member abuttingly engages the first coupling member.

27. The brake lever assembly of claim 21, wherein the master piston is a first master piston, the master piston assembly further comprises a second master piston, the first master piston has a hole, and the second master piston is at least partially disposed in the hole.

28. The brake lever assembly of claim 21, wherein the adjustable connector has a longitudinal axis, the master cylinder has a longitudinal axis, and the adjustable connector's longitudinal axis is substantially parallel to the master cylinder's longitudinal axis.

29. A brake lever assembly, comprising: a housing; a master cylinder disposed in the housing, the master cylinder having a port; a master piston assembly disposed in the master cylinder, the master piston assembly comprising a master piston, the master piston having a seal and a non-actuated state; a lever pivotally connected to the housing, the lever having first and second forked portions and a space between the first and second forked portions; an adjustable connector disposed in the space and operatively connecting the lever to the master piston; wherein the seal and the port define a distance when the master piston is in the non-actuated state, and the adjustable connector is adjustable to vary the distance.

30. The brake lever assembly of claim 29, wherein the lever further comprises a cross member connecting the first forked portion and the second forked portion, and the adjustable connector is disposed through the cross member.

Description

[0071] It is preferred that housing 14 include a hydraulic fluid reservoir 42 for storing hydraulic fluid. Two ports, a timing port 44 and a compensating port 46 are preferably provided to allow hydraulic fluid to flow between reservoir 42 and master cylinder 31. As best shown in FIGS. 3-5, first fluid passage 87 connects reservoir 42 to second fluid containing area 86. As best shown in FIGS. 6-8, a second fluid passage 88 connects second fluid containing area 86 and first fluid containing area 82. Thus, when lever 41 is in the neutral position as shown in FIG. 3, timing port 44 is in fluid communication with first fluid containing area 82 and fluid conduit attachment 84 via first fluid passage 87, second fluid containing area 86 and second fluid passage 88.

[0072] If a hydraulic disc brake is attached to lever assembly 10, when lever 41 is in the neutral position of FIG. 3 or farther away from handlebar 12, the total liquid volume of the hydraulic brake system will include the volume of reservoir 42. As a result, the pressure at second fluid containing area and hydraulic fluid conduit 84 will be relatively low. However, as lever 41 is moved to the first actuating position shown in FIG. 4, the operative connection between lever 41, and first piston 32 causes first piston 32 and seal 58 to move towards master cylinder bottom end 31b. When seal 58 reaches timing port 44, first fluid passage 87 is substantially isolated from timing port 44 and reservoir 42. At this point, the overall hydraulic system volume which is available for actuating the brake system is reduced, and the system pressure begins to correspondingly increase. If the attached disc brake's fluid conduits are already liquid full, further movement will move the slave piston(s) and the attached brake pads, towards the rotor.

[0073] As indicated above, first and second pistons 32 and 34 preferably move together when lever 41 is between the neutral and first acutating positions. To facilitate this movement, spring 60 is preferably selected such that it applies greater force to outer piston 32 than does second spring 78 as lever 41 is moved from the neutral position to the first actuating position. It is especially preferred that spring 60 have a spring constant or stiffness that is greater than spring 78, wherein the stiffness or spring constant is defined by the relationship k=F/x, with F being equal to the force required to linearly compress the spring a distance x. As a result of the differential spring strengths, as lever 41 is moved from the neutral position of FIG. 3 to the first actuating position of FIG. 4, second piston engagement surface 59 of first piston flange 55 will abuttingly engage first piston engaging surface 69 of second piston 32, causing first piston 32 to move towards master cylinder bottom end 31b along with second piston 34. Accordingly, fluid will be displaced from second fluid containing region 86 to first fluid containing region 82 via second fluid passage 88 and from first fluid containing region 82 to hydraulic fluid conduit attachment 84 via exit port or fluid outlet 83.

[0074] As will be apparent to those of ordinary skill in the art, as lever 41 is moved from the neutral position of FIG. 3 to the first actuating position of FIG. 4, the volume of hydraulic fluid displaced to the exit port or fluid outlet 83 of master cylinder 31 will equal the sum of the volumes of fluid displaced from the first and second fluid containing regions 82 and 86. In a preferred embodiment, as lever 41 is moved from the neutral position to the first actuating position, at least one of the friction members or brake pads of an attached disc brake system will move from a position in which it does not contact the rotor to one in which it contacts the rotor. It is especially preferred that once the first actuating position of FIG. 4 is reached, the brake pad will have just come into contact with the rotor without applying appreciable pressure to it. One skilled in the art will readily appreciate how to select the dimensions of master cylinder 31, pistons 32 and 34, hydraulic conduit 84 and the disc brake caliper components to obtain a brake lever and brake system in which the brake pad contacts the rotor without applying appreciable pressure once lever 41 reaches the first actuating position.

[0075] As indicated in FIG. 4, once lever 41 reaches the first actuating position, first piston 32 will be at a threshold distance from the master cylinder top end 31a at which seal 80 will preferably close off the outlet of second fluid passage 88. Closure of the outlet of second fluid passage 88 will substantially isolate first fluid containing region 82 from second fluid containing region 86. As a result, negligible or no hydraulic fluid will enter or leave second fluid containing region 86. Because the volume of fluid in second fluid containing region 86 will be substantially fixed and because liquids such as known hydraulic fluids are substantially incompressible, second piston engagement surface 59 of first piston 32 will be biased away from first piston engagement surface 69 of second piston 34 and towards the top end 31a of master cylinder 31. As best shown in FIG. 5, at this point, further movement of lever 41 towards handlebar 12 will cause second piston 34 to separate from first piston 32, such that second piston 34 moves towards master cylinder bottom end 31b, while first piston 32 remains substantially stationary. Thus, the distance from master cylinder top end 31a to the outlet of second fluid passage 88 effectively defines a first movement region along the length of master cylinder 31, such that when master piston assembly 33 is within the first movement region, first piston 32 and second piston 34 move together. However, once second-piston 34 begins to exit the first movement region and is at least partially outside of it, second piston 34 moves with respect to first piston 32.

[0076] If brake lever assembly 10 is attached to a hydraulic disc brake, once the brake pads contact the rotor, the volume of liquid which can be displaced from master cylinder 31 will be relatively small. Because typical hydraulic fluids are substantially incompressible, further movement of inner piston 34 towards master cylinder bottom end 31b will increase the system hydraulic pressure and the frictional force applied to the rotor. However, some liquid will be displaced from master cylinder 31 even after the brake pads contact the rotor due to a variety of factors such as the compressibility of the brake pads, the expansion or extension of the hydraulic conduit, which is typically a flexible hose, or due to system leakage.

[0077] A preferred embodiment of a method of using a hydraulic disc brake lever assembly 10 made in accordance with the foregoing embodiments will now be described. In accordance with the method, a bicycle is provided having a rotor on its front or back wheel. A hydraulic disc brake caliper, for example the caliper of FIG. 16 in the '144 Patent, is attached to the wheel to which the rotor is attached such that its brake pads are positioned on either side of the rotor.

[0078] In accordance with the method, the bicycle is provided with a hydraulic disc brake lever assembly 10 attached to a handlebar 12. At some point when the bicyclist is riding the bicycle, he or she will want to slow or stop the bicycle by applying the brakes. At that time, the rider will grip handlebar 12 and will also grip lever 41 in relatively flat region 41a. As indicated earlier, handlebar 41 is preferably configured to restrict the rider's lateral movement of his or her hand along the length of the lever 41. The rider will then contract lever 41 towards handlebar 12 at a substantially constant rate of speed. Due to the operative connection of lever 41 and master piston assembly 33, first piston 32 and second piston 34 will begin to move towards bottom end 31b of master cylinder 31 while remaining within the first movement region defined by the master cylinder top end 31a and the outlet of fluid passage 88. During this motion of lever 41, hydraulic fluid will be displaced from second fluid containing region 86 into first fluid containing region 82 and from first fluid containing region 82 to hydraulic conduit attachment 84. As a result, hydraulic fluid will begin to fill the hydraulic fluid conduits within the caliper housing (unless the caliper housing conduits are already liquid full). Once the conduits are full of hydraulic fluid, pressure will be applied to the disc brake slave pistons, moving them towards the rotor. During this time, no braking will occur.

[0079] The rider will preferably continue to contract lever 41 at the same substantially constant rate of speed. As he or she continues to do so, lever 41 will reach a first actuating position (see FIG. 4), at which time first piston 32 will preferably reach a threshold distance from master cylinder top end 31a. Cup seal 80 will then preferably close off the outlet of second fluid passage 88 from second fluid containing region 86. At this point, the volume of fluid contained in second fluid containing region 86 will be substantially fixed, and as a result, the fluid will begin to bias first piston 32 towards master cylinder top end 31a. Thus, further movement of lever 41 towards handlebar 12 will cause second piston 34 to separate from first piston 32 and move towards master cylinder bottom end 31b as it exits the first movement region of master cylinder 31 (see FIG. 5). However, first piston 32 will remain substantially stationary. Also, once lever 41 reaches its first actuating position, the brake pads will preferably make contact the rotor without applying appreciable pressure to it. A first volume of hydraulic fluid, V1, will be displaced during this first movement of lever 41 from the neutral position to the first actuating position.

[0080] The rider will preferably continue to contract lever 41 from the first actuating position to the second actuating position at the same rate of speed used to contract the lever from the neutral position to the first actuating position. At this point, because the brake pads are in contact with the rotor, the system pressure will begin to rise and the frictional resistance applied by the brake pads to the rotor will increase. Because second fluid containing region 86 will be substantially isolated from first fluid containing region 82, the total volume of hydraulic fluid delivered from lever assembly 10 to the disc brake caliper housing, as lever 41 is moved from the first actuating position to the second actuating position, V2, will be less than V1. Thus, according to the preferred embodiment of this method, a larger amount of fluid is delivered in the first region of travel of brake lever 41 than in a second region of travel. In an especially preferred embodiment, the method will provide two-stage braking in which the ratio of fluid volume displaced from master cylinder assembly 31 to lever travel will vary as lever 41 is contracted towards handlebar 12. As those skilled in the art will appreciate, for a given displacement of lever 41 within the first region of its range of travel, a greater volume of hydraulic fluid will be discharged from master cylinder assembly 31 than when lever 41 is displaced the same distance within the second region.

[0081] As mentioned earlier, in known hydraulic brake assemblies there is typically a "dead band" as the rider begins to contract the lever during which no braking occurs. As used herein, the term "dead band" means the distance between the seal of a master piston and a hydraulic fluid reservoir port when the master piston is in its non-actuated or rest state.

[0082] As explained earlier with respect to the preferred embodiment of FIG. 3, when lever 42 is in its neutral position, first piston 32 and second piston 34 are in their non-actuated states and timing port 44 is in fluid communication with first fluid containing area 86 and fluid conduit attachment 84. When first piston 32 is in its non-actuated state, the dead band is the distance between seal 58 and timing port 44, as measured along the lengthwise direction of master cylinder 31.

[0083] In accordance with a preferred embodiment of the present invention, master cylinder assembly 30 has an adjustable dead band. The adjustable dead band preferably allows users to compensate for system hydraulic changes (e.g., changes in the shape or effective length of hydraulic fluid conduit 84 or in the attached brake system) to maintain a consistent braking feel and operation.

[0084] Even more preferably, the dead band of master cylinder assembly 30 is adjustable without affecting the reach or neutral position of lever 41. As used herein, the term "reach" refers to the range of travel between the neutral and fully actuated positions of lever 41.

[0085] In the preferred embodiment of FIGS. 1-8, users may adjust the dead band by adjusting fastener 40. The dead band is adjustable within a range that is generally from about 2.0 to about 3.0 mm, preferably from about 2.2 to about 2.8 mm, and more preferably from about 2.4 to about 2.6 mm. Fastener 40 is preferably adjustable using conventional tools such as a screw driver or Allen wrench. Fastener 40 is also preferably externally threaded to engage complementary threads formed in through-hole 92 of actuating member 38. As a result of this threaded engagement, rotation of fastener 40 causes it to move with respect to actuating member 38 along the lengthwise direction of master cylinder 31.

[0086] In accordance with this preferred embodiment, fastener 40 is secured to male-female coupling member 90 by known means, such as threaded engagement, welding, gluing, or a snap-fit connection. Male end 90b of male-female coupling member 90 preferably abuttingly engages wide end 66 of dual female connector 62 without being rigidly attached to it. To provide a more stable connection, a post, setting boss or other protrusion may be included on male end 90b which engages a complementary hole formed in wide end 66 of dual-female coupling member 62.

[0087] The engagement of male-female coupling member 90 and dual female connector 62 preferably allows male-female coupling member 90 to rotate with respect to dual female coupling member 62. As a user rotatably adjusts fastener 40, it moves along the lengthwise direction of master cylinder 31 and with respect to actuating member 38. The adjustment of fastener 40 also causes male-female coupling member 90 to rotate and move in the lengthwise direction of master cylinder 31 with fastener 40. To better facilitate this axial movement, forked proximal end 47 of lever 41 is preferably sized to receive male-female coupling member 90.

[0088] In FIGS. 3-5, fastener 40 is fully-seated in cross-member through-hole 92. As a result, the dead band of master cylinder assembly 30 is at a minimum. As fastener 40 is rotated in a first direction, it will move with respect to actuating member 38 and away from master cylinder bottom end 31b. Male-female coupling member 90 will also rotate and move with actuating member 38. As male-female coupling member 90 moves away from master cylinder bottom end 31b, it will initially separate from dual-female coupling member 62. However, the biasing action of springs 60 and 78 will move first piston 32 and second piston 34 away from master cylinder bottom end 31b until wide end 66 of dual female coupling member 62 again abuttingly engages male end 90b of male-female coupling member 90. As a result, the rest or non-actuating state of first piston 32 will change, thereby moving seal 58 away from timing port 44 and increasing the dead band of master cylinder assembly 30.

[0089] If the dead band is not at its minimum (i.e., fastener 40 is not fully-seated in cross-member through-hole 92) the dead band may be decreased by the user. To decrease the dead band, fastener 40 is preferably rotated in a second direction, which is opposite the first direction referenced above. As fastener 40 is rotated in the second direction, it will move with respect to actuating member 38 towards master cylinder bottom end 31b. As a result, male-female coupling member 90 will also move toward bottom end 31b. As male-female coupling member 90 moves towards bottom end 31b, it will force dual female coupling member 62 in the same direction, thereby compressing spring 78 and changing the non-actuated state of first piston 32. As a result, the distance between seal 58 and timing port 44 will decrease, thereby decreasing the dead band.

[0090] It is especially preferred that the dead band of master cylinder assembly 30 is adjustable without affecting the lever's reach. Referring to FIG. 3, lever 41 is in a neutral position and first piston 32 is in a non-actuated state. As lever 41 is actuated, it will eventually reach a fully-actuated position at which no further actuation is possible.

[0091] The design of various components in brake lever assembly 10 may limit the fully-actuated position of lever 41. However, to better ensure that adjustments to the dead band do not affect the lever's reach, the fully-actuated position of lever 41 is preferably not limited by the abutment of second piston fluid contacting flange 74 and master cylinder bottom end 31b. Instead, it is preferred to use other components of brake lever assembly 10 to limit the lever's fully-actuated position, as described below.

[0092] For example, depending on their length, slots 28a and 28b may be used to limit the fully-actuated position of lever 41. As lever 41 is contracted towards handlebar 12, actuating member 38 will move along slot pair 28 until it reaches the bottom of slots 28a and 28b. At this point, no further actuation will be possible.

[0093] In addition, the brake lever assembly 10 may be configured such that the abutment of lever 41 and handlebar 12 limits the lever's fully actuated position. Housing second section 26 and/or clamp 13 may be sized to ensure that lever 41 abuttingly engages handlebar 12 before actuating member 38 reaches the bottom of slot pair 28 and before flange 72 of second piston 34 reaches master cylinder bottom end 31b. This configuration will also prevent changes in dead band from affecting changes in the reach of lever 41.

[0094] Brake lever assembly 10 also preferably includes reach adjustment. Even more preferably, the reach is adjustable without affecting the dead band. In the preferred embodiment of FIGS. 1-8, the neutral position of lever 41 may be adjusted to vary the lever's reach without affecting the dead band.

[0095] As described previously, the vertical position of pivot member 22 in housing first section 16 may be adjusted to vary the lever's neutral position. To adjust the neutral position, a user rotates adjustable fastener 20, thereby moving pivot member 22 within slot pair 18. Because of the biasing action of springs 60 and 78, as pivot member 22 moves along slot pair 18, actuating member 38 will remain biased against the top of slot pair 28. As a result, lever 41 will pivot about the longitudinal axis 102 of actuating member 38 until further adjustment of pivot member 22 stops. Because the position of actuating member 38 with respect to slot pair 28 is unchanged by this operation, the dead band of master cylinder assembly 30 will be substantially unaffected by the adjustment of the lever's reach.

[0096] In accordance with the preferred embodiment of FIGS. 1-8, the reach of lever 41 is adjusted by pivoting lever 41 about a lever region (i.e., the region of lever 41 lying between slots 28a and 28b) that is spaced apart from the longitudinal axis of pivot member 22 and which is substantially aligned with master cylinder 31. More preferably, lever 41 is pivoted about the longitudinal axis 102 of actuating member 38 to adjust the reach. As indicated in FIGS. 1-2, it is especially preferred that the longitudinal axis 102 is substantially parallel to longitudinal axis 104 and also substantially perpendicular to the longitudinal axis 106 of master cylinder 31.

[0097] This preferred embodiment allows the user to adjust the reach of lever 41 without affecting the dead band of master cylinder assembly 30, and conversely, to adjust the dead band of master cylinder assembly 30 without affecting the reach of lever 41. It also provides a lever 41 which is pivotable about a first axis (longitudinal axis 104 of pivot member 22) to actuate first piston 32 and second piston 34 and about a second axis (longitudinal axis 102 of actuating member 38) to adjust the lever's reach.

[0098] The reach and dead band adjustment features of this preferred embodiment have been described in the context of a dual-piston master cylinder assembly. However, it should be understood that a dual piston configuration is not required to provide the reach and dead band adjustment features described herein. For example, if first piston 32 and second piston 34 were instead replaced with a single piston, spring 60 could be eliminated. Spring 78 could also be configured to bias the single piston away from master cylinder bottom end 31b. In an exemplary embodiment, one end of spring 78 would abuttingly engage the master cylinder bottom end 31b while the other end would engage a bottom surface of the single piston. As with the dual piston embodiment, the axial movement of fastener 40 with respect to actuating member 38 would result in the movement of the non-actuated position of a seal formed on the single piston to adjust the dead band. Thus, lever 41 would be pivotable about longitudinal axis 104 of pivot member 22 to actuate the single piston and would also be pivotable about longitudinal axis 102 of actuating member 38 to adjust the neutral position, and hence the reach, of lever 41.

[0099] The embodiments described above are exemplary embodiments of a the present invention. Those skilled in the art may now make numerous uses of, and departures from, the above-described embodiments without departing from the inventive concepts disclosed herein. Accordingly, the present invention is to be defined solely by the scope of the following claims.