Patent Publication Number: US-7909415-B2

Title: Locking hydraulic brake system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 11/657,999, filed on Jan. 25, 2007 and priority is claimed under 35 U.S.C. §120. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a locking hydraulic brake system. More particularly, the invention relates to locking mechanisms for installing between a master cylinder and a brake line. The invention further relates to a locking master cylinder assembly. 
     2. The Prior Art 
     Locking hydraulic brake systems or parking brakes according to embodiments of the invention may be used in various types of vehicles having hydraulically actuated brakes, for example automobiles, motorcycles, all-terrain vehicles and snowmobiles. A locking mechanism and a locking master cylinder assembly according to embodiments of the invention are particularly suited for use with a front or rear brake assembly of a motorcycle. 
     A motorcycle front brake system typically includes a hand-operated lever disposed on the right handlebar grip, along with the throttle. This lever operates a piston within a master cylinder assembly which is also secured to the right handlebar. Squeezing the brake lever forces hydraulic fluid from the master cylinder through a “banjo bolt” fitting and brake line to the front brake caliper to operate the brake. When the brake lever is released, the hydraulic fluid is allowed to flow back to the master cylinder, and the brake is released. 
     Existing motorcycle front brake systems generally do not include any type of locking mechanism, and accordingly when an operator is stopped on an incline, the operator must maintain pressure on the brake lever with his or her right hand to prevent the vehicle from rolling backward, while simultaneously twisting the throttle with the right hand to warm the engine. This is a difficult procedure and the motorcycle may roll backwards (“rollback”) if not performed properly. Additionally, using the rear brake to hold the motorcycle has the disadvantage of requiring the operator to balance the bike with just one leg as the other foot must be used to depress the rear brake foot pedal used to actuate the rear brake. 
     A number of devices and systems for locking a brake on a vehicle such as a motorcycle, all-terrain vehicle or snowmobile are known. The following references, the disclosures of which are hereby incorporated by reference, relate to mechanisms for locking a vehicle brake in an engaged state. 
     U.S. Pat. No. 5,327,724 Tribuzio et al. shows a lockable master cylinder having a reversible electric motor for locking the piston in a rest or working position to keep the vehicle brake applied. 
     U.S. Patent Application Publication No. 2006/0076197 to Ishida, U.S. Pat. No. 6,450,301 to Iizuka et al. and corresponding Japanese Patent No. JP 2002/079981 A to Iizuka et al., each show a locking motorcycle rear brake system which requires an additional caliper to serve as a parking brake for the motorcycle rear wheel. 
     U.S. Pat. No. 3,498,361 to Carlson and U.S. Pat. No. 5,857,385 to Takeuchi describes devices for locking a lever which operate a cable-type mechanical brake. 
     U.S. Patent Application Publication No. 2006/0071542 to Lichtensteiger et al. shows a handlebar master cylinder assembly with a park pawl which engages a bracket connected to the master cylinder body to maintain the brake lever locked in an applied position. The park pawl flexes to compensate for hydraulic fluid temperature changes and maintain proper brake pressure. 
     Japanese Patent No. JP 411-189189 to Sekiya shows a parking brake device for a hydraulic motorcycle brake. the device has a sliding piston mounted in a cylinder adjacent the brake lever and an end of the piston contacts an end surface of the brake lever to set the parking brake. 
     Japanese Patent No. JP2003/112684 A to Igarashi shows a motorcycle parking brake with a brake lock lever mounted on the left handlebar for braking a drum brake of a motorcycle&#39;s rear wheel. 
     U.S. Pat. No. 4,041,798 to Shinozaki et al. shows a pawl and cam mechanism for locking a foot pedal which actuates a motorcycle rear brake. 
     The devices and systems for locking a vehicle brake as disclosed in the references cited above exhibit several deficiencies. In particular, the known systems are complicated and costly and are not easily adaptable to a vehicle&#39;s original equipment manufactured (OEM) braking system. Some of the known locking systems require additional brake calipers or electronics and solenoids. In addition, the known devices generally require substantial modification to a conventional vehicle brake system to implement. 
     Accordingly there exists a need for a simple and inexpensive locking brake mechanism which can be easily installed on an existing vehicle hydraulic brake system, such as a motorcycle front or rear brake system. Additionally, the need exists for a locking or parking system comprising a simple mechanical device which can be added to an existing motorcycle front or rear brake system as an aftermarket item or supplied as original equipment. 
     SUMMARY OF THE INVENTION 
     A locking mechanism for installing between a master cylinder containing hydraulic fluid and a brake line for operating a vehicle brake according to a first embodiment of the invention includes a housing which is secured to the master cylinder. The housing has an internal bore, an inlet port in fluid communication with the internal bore, a passage in fluid communication with the inlet port, and an outlet port in fluid communication with the internal bore and with the brake line. 
     A lid may be disposed on the housing and a reciprocating piston is disposed within the internal bore in a movable manner. A locking lever is coupled to the reciprocating piston for actuating the reciprocating piston. A portion of the locking lever may be in abutting contact with the reciprocating piston. 
     The housing is secured to the master cylinder with a fastener having an internal fluid passage for providing fluid communication between the passage in the housing and the master cylinder. 
     The locking lever is moveable between a first, or unlocked position, wherein the hydraulic fluid can flow freely between the master cylinder and the brake line for engaging and disengaging the vehicle brake and a second, or locked position, wherein the hydraulic fluid is prevented from returning to the master cylinder for maintaining the vehicle brake in an engaged state. 
     A locking master cylinder assembly for supplying pressurized hydraulic fluid through a brake line to operate a vehicle brake according to another embodiment of the invention includes a housing having a reservoir for containing the hydraulic fluid. The housing has a first internal bore in fluid communication with the reservoir, a second internal bore, a passage for providing fluid communication between the first and second internal bore and an outlet port in fluid communication with the second internal bore and with the brake line. 
     A first reciprocating piston is movable within the first internal bore for pressurizing the hydraulic fluid to engage the vehicle brake in response to input from a vehicle operator. 
     A lid is disposed on the housing and a second reciprocating piston is disposed within the second internal bore in a movable manner. A locking lever for actuating the second reciprocating piston is pivotally coupled to the lid. A portion of the locking lever is in abutting contact with the second reciprocating piston. 
     The locking lever is moveable between a first, or unlocked position, wherein the hydraulic fluid can flow freely between the first internal bore and the brake line for engaging and disengaging the vehicle brake and a second, or locked position, wherein the hydraulic fluid is prevented from returning to the first internal bore for maintaining the vehicle brake in an engaged state. 
     A locking mechanism for remotely mounting between a first brake line coupled to a master cylinder containing hydraulic fluid and a second brake line coupled to a vehicle brake according to another embodiment of the invention includes a housing coupled to the first and second brake lines. The housing has an internal bore, an inlet port in fluid communication with the internal bore and the first brake line, and an outlet port in fluid communication with the internal bore and the second brake line; 
     A lid may be disposed on the housing and a reciprocating piston is movable within the internal bore. A locking lever is coupled to the reciprocating piston for actuating the reciprocating piston. A portion of the locking lever may be in abutting contact with the reciprocating piston. 
     The locking lever is moveable between a first, or unlocked position, wherein the hydraulic fluid can flow freely between the first brake line and the second brake line for engaging and disengaging the vehicle brake and a second, or locked position, wherein the hydraulic fluid is prevented from flowing between the first brake line and the second brake line for maintaining the vehicle brake in an engaged state. 
     An advantage of a locking mechanism or locking master cylinder assembly according to an embodiment of the invention is that it is simple to install and operate. A locking mechanism or locking master cylinder assembly according to an embodiment of the invention employs a simple mechanical valve design and does not require a solenoid, electronics, or extensive modification of the brake system, as do known brake lock devices. 
     Moreover, a locking mechanism or locking master cylinder assembly according to an embodiment of the invention has many advantageous uses, including preventing rollback when stopped on an incline, providing stability when the motorcycle is being transported by flatbed, van, truck or trailer, and eliminating the need to shut off the engine and put the motorcycle in gear to prevent rolling when dismounting the motorcycle, for example to open a garage door in order to store the motorcycle. 
     Another advantageous use of a locking mechanism or locking master cylinder assembly according to an embodiment of the invention is in performing a motorcycle stunt or trick known as a “burnout” by locking the front brake, revving the engine and quickly releasing the clutch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other benefits and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention. 
       In the drawings, wherein similar reference characters denote similar elements throughout the several views: 
         FIG. 1  shows a locking mechanism according to an embodiment of the invention with a locking lever in a first, or unlocked position; 
         FIG. 2  shows the locking mechanism of  FIG. 1  with the locking lever in a second, or locked position; 
         FIG. 3  shows a locking mechanism having a tapered conical seal according to another embodiment of the invention; 
         FIG. 4  shows a locking master cylinder assembly according to another embodiment of the invention; 
         FIG. 5  shows the locking master cylinder assembly of  FIG. 4  mounted on a vehicle handlebar; 
         FIG. 6  shows a remote mounted locking mechanism for a hydraulic brake system according to another embodiment of the invention; and 
         FIG. 7  shows the locking master cylinder assembly of  FIG. 4  coupled to a foot pedal for operating a motorcycle rear brake. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now in detail to the drawings and, in particular,  FIG. 1  shows a locking mechanism according to an embodiment of the invention with a locking lever in a first, or unlocked position.  FIG. 2  shows the same locking mechanism with the locking lever in a second, or locked position. As shown, locking mechanism  1  may be installed between a master cylinder  100  containing hydraulic fluid and a brake line  200  for operating a vehicle brake. 
     Locking mechanism  1  includes a housing  10 . Housing  10  may be constructed from metal, for example billet or cast aluminum, stainless steel, cast iron, magnesium or brass, from plastic or from any other suitable material. Housing  10  includes an internal bore  11 . Internal bore  11  defines a movement space for a reciprocating piston  12 . As shown, reciprocating piston  12  may comprise an upwardly biased member. A spring member  13  may serve as a biasing element for reciprocating piston  12 . One or more sealing members, for example a ring-type seal may be provided on reciprocating piston  12  for sealing piston  12  within bore  11 . 
     As shown in  FIG. 3 , reciprocating piston  12  may include a tapered conical seal  14 , which along with reciprocating piston  12 , bore  11  and housing  10  form a needle-type valve. Tapered conical seal  14  may comprise a rubber tip or other suitable material for forming a tight seal. Additionally, as shown in  FIG. 3 , the hydraulic fluid may be permitted to flow through passages or channels in reciprocating piston  12  to prevent unnecessary or excessive compression in the brake line when the locking mechanism is engaged. 
     Housing  10  further includes an inlet port  15  which is in fluid communication with internal bore  11 , thereby allowing hydraulic fluid to flow between a passage  16  and the bore  11 . An outlet port  17  is in fluid communication with the bore  11  and with the brake line  200 , thereby allowing hydraulic fluid to flow between the brake line  200  and bore  11 . Housing  10  may also include one or more breather ports for providing air pressure to the piston bore. 
     A lid  20  may be disposed on housing  10 . Alternately, the mechanism may comprise a housing without a lid. Lid  20  may be fastened to housing  10  such that a seal is formed therebetween. For example an O-ring type seal or other appropriate sealing member may be used to provide a seal between lid  20  and housing  10 . 
     A locking lever  30  for actuating reciprocating piston  12  is coupled to reciprocating piston  12 . Preferably, locking lever  30  is pivotally coupled to lid  20 . As shown, a portion of locking lever  30  may be in abutting contact with reciprocating piston  12  such that as locking lever  30  is pivoted, reciprocating piston  12  moves within internal bore  11 . Preferably, locking lever  30  has a rounded camming surface portion  31 , a flattened surface portion  32  and a projecting tab  33  for retaining locking lever  30  in a locked position as shown, for example, in  FIG. 2 . 
     Lid  20  may be secured to housing  10  using a plurality of fasteners  40 , for example bolts or other suitable fasteners. Fasteners  20  may be inserted into opening provided in housing  10 . Housing  10  may include a plurality of openings for receiving fasteners  40  such that lid  20  and locking lever  30  pivotally coupled thereto may be secured to housing  10  in a plurality of orientations. For example, lid  20  may be fastened to housing  10  using two lid bolts and housing  10  may include six openings for the lid bolts wherein the openings are positioned to allow lid  20  to be mounted in a number of orientations. In this manner, lid  20  with locking lever  30  can be rotated with respect to housing  10  to suit a particular application and/or operator. 
     Housing  10  is secured to the master cylinder  100  with a fastener  50 . Fastener  50  includes an internal fluid passage  51  for providing fluid communication between passage  16  and an output port of the master cylinder. Fastener  20  may be, for example a banjo bolt which is similar to the fastener used to secure a brake line to a master cylinder. Preferably, fastener  50  is secured in an opening in master cylinder  100  previously used for securing brake line  200  using a banjo type bolt. In this way, locking mechanism  1  is adapted to be installed on a conventional master cylinder assembly without any significant modifications. Locking mechanism  1  can be designed to be compatible with many types and makes of vehicles, for example motorcycle master cylinders supplied as original equipment by various manufacturers. 
     As shown in  FIGS. 1 and 2 , locking lever  30  is moveable between a first, or unlocked, position ( FIG. 1 ), wherein the hydraulic fluid can flow freely between the master cylinder  100  and the brake line  200  for engaging and disengaging the vehicle brake and a second, or locked position ( FIG. 2 ), wherein the hydraulic fluid is prevented from returning to the master cylinder  100 . This second position maintains the vehicle brake in an engaged state keeping hydraulic pressure on the brake, while allowing the operator to release the brake lever or pedal used to engage and release the brake. 
     Locking lever  30  may be a hand-operated lever as shown in  FIGS. 1-3 , or alternatively a foot-operated lever. In addition a locking mechanism as described above may be secured to a master cylinder mounted to a vehicle handlebar, for example a motorcycle handlebar, or may be secured to a master cylinder mounted in any other location on a vehicle. 
     When locking lever  30  is in an unlocked position, for example the horizontal position shown in  FIG. 1 , hydraulic fluid can flow freely through the unit and the brake, for example a motorcycle front brake, can be operated in the usual manner, for example by squeezing a front brake lever. When locking lever  30  is in a locked position, for example the vertical position shown in  FIG. 2 , reciprocating piston  12  may be depressed and hydraulic fluid is prevented from returning to the master cylinder  100 . This maintains pressure in the front brake line  200  and keeps the brake engaged. 
     In order to operate a locking mechanism or locking master cylinder according to an embodiment of the invention, a vehicle operator first applies pressure to the brake in the usual manner (for example by squeezing a motorcycle front brake lever or depressing a motorcycle rear brake foot pedal). Next, the operator engages the locking mechanism by moving a locking lever  30  to a locked position. To release the locking mechanism, the operator merely moves the locking lever  30  to its unlocked position, allowing the hydraulic fluid to flow back and releasing the pressure on the brake. 
       FIG. 4  shows a locking master cylinder assembly  2  for supplying pressurized hydraulic fluid through a brake line  200  to operate a vehicle brake. The components on the right side of the dividing line in  FIG. 4  may comprise a standard master cylinder setup, for example a handlebar mounted hand-operated motorcycle front brake master cylinder or a foot pedal operated motorcycle rear brake master cylinder. The components on the left side of the dividing line in  FIG. 4  are added to the standard master cylinder setup to provide a means for holding pressure on the brake once and locking the wheel against rotation once the brake has been applied in the conventional manner by hand or foot pressure. 
     Locking master cylinder assembly  2  includes housing  202 . A reservoir  204  for containing the hydraulic fluid is formed within housing  202 . A first internal bore  206  in fluid communication with reservoir  204  and a second internal bore  208  are also disposed within housing  202 . 
     A passage  210  is provided in housing  202  for providing fluid communication between first internal bore  206  and second internal bore  208 . As shown, passage  210  may comprise a narrow channel extending between the two bore or chambers. An outlet port  212  in fluid communication with second internal bore  208  and brake line  200  is also disposed within housing  202 . 
     A first reciprocating piston  214  for pressurizing the hydraulic fluid to engage the vehicle brake in response to input from a vehicle operator (indicated in  FIG. 4  by an arrow pointing from right to left) is movable within first internal bore  206 . This arrangement of first piston and bore may comprise an arrangement found in standard, non-locking master cylinder devices. 
     A second reciprocating piston  216  is disposed in housing  202  and movable within second internal bore  208 . As shown, second reciprocating piston  216  may include a tapered conical seal  218 , which along with second reciprocating piston  216 , second internal bore  208  and housing  202  form a needle-type valve. Tapered conical seal  218  may comprise a rubber tip or other suitable material for forming a tight seal. Additionally, as shown in  FIG. 4 , the hydraulic fluid may be permitted to flow through passages or channels in second reciprocating piston  216  to prevent unnecessary or excessive compression in the brake line when the locking mechanism is engaged. 
     A lid  220  is disposed on housing  202 . Lid  216  may be fastened to housing  202  such that a seal is formed therebetween. For example an O-ring type seal or other appropriate sealing member may be used to provide a seal between lid  220  and housing  202 . A locking lever  30  for actuating second reciprocating piston  216  is pivotally coupled to lid. A portion of locking lever  30  may be in abutting contact with second reciprocating piston  216  such that as locking lever  30  is pivoted, second reciprocating piston  216  moves within second internal bore  208 . Preferably, locking lever  30  has a rounded camming surface portion, a flattened surface portion and a projecting tab for retaining locking lever  30  in a locked position as shown, for example, in the lever illustrated in  FIG. 2 . 
     As in the previous embodiment, lid  220  may be secured to housing  202  using a plurality of fasteners, for example bolts or other suitable fasteners. Fasteners may be inserted into openings provided in housing  202 . Housing  202  may include a plurality of openings for receiving fasteners such that lid  220  and locking lever  30  pivotally coupled thereto may be secured to housing  202  in a plurality of orientations. For example, lid  220  may be fastened to housing  202  using two lid bolts and housing  202  may include six openings for the lid bolts wherein the openings are positioned to allow lid  220  to be mounted in a number of orientations. In this manner, lid  220  with locking lever  30  can be rotated with respect to housing  202  to suit a particular application and/or operator. 
     Locking lever  30  is moveable between a first, or unlocked position, wherein the hydraulic fluid can flow freely between first internal bore  206  and the brake line  200  through outlet port  212  for engaging and disengaging the vehicle brake and a second, or locked position, wherein the hydraulic fluid is prevented from returning to the first internal bore for maintaining the vehicle brake in an engaged state. This second position maintains the vehicle brake in an engaged state keeping hydraulic pressure on the brake, while allowing the operator to release the brake lever or pedal used to engage and release the brake. 
     As shown, when locking lever  30  is in a first or unlocked position, hydraulic fluid is permitted to flow from reservoir  204  to first internal bore  206 , from first internal bore  206  through passage  210 , from passage  210  to second internal bore  208 , and from second internal bore  208  out to brake line  200  via outlet port  212 . In this state, the brake, for example a motorcycle front brake, can be operated in the usual manner, for example by squeezing a front brake lever. When locking lever  30  is in a locked position, second reciprocating piston  216  may be depressed and hydraulic fluid is prevented from returning to the first internal bore  206  This maintains pressure in the brake line  200  and keeps the brake engaged. 
     In order to operate a locking master cylinder assembly according to an embodiment of the invention, a vehicle operator first applies pressure to the brake in the usual manner (for example by squeezing a motorcycle front brake lever or depressing a motorcycle rear brake foot pedal). Next, the operator engages the locking mechanism by moving a locking lever  30  to a locked position. To release the locking mechanism, the operator merely moves the locking lever  30  to its unlocked position, allowing the hydraulic fluid to flow back and releasing the pressure on the brake. 
     Locking lever  30  for locking master cylinder assembly  2  may be a hand-operated lever as shown in  FIGS. 4 and 5 , or alternatively a foot-operated lever as shown in  FIG. 7 . As shown in  FIG. 5 , a locking master cylinder assembly  2  as described above may mounted to a vehicle handlebar  222 , for example a motorcycle handlebar, wherein the locking master cylinder assembly  2  is operable to lock a front brake of the motorcycle. As shown in  FIG. 7 , a locking master cylinder assembly  2  as described above may be mounted such that first reciprocating piston  214  is coupled to a foot pedal  224  and is for operating a rear brake of the vehicle. 
       FIG. 6  shows a remote mounted locking mechanism  3  for a hydraulic brake system according to another embodiment of the invention. Remote mounted locking mechanism  3  is similar to the locking mechanism shown  FIGS. 1-3  and described above, however rather than being secured to the master cylinder  100 , the locking mechanism  3  is mounted remote from the master cylinder  100  and between a first brake line  300  coupled to master cylinder  100  and a second brake line  200  coupled to a vehicle brake. Remote mounted locking mechanism  3  may be mounted to a vehicle&#39;s frame or handlebar. For example, remote mounted locking mechanism  3  may be clamped to a motorcycle frame or bolted thereto using a bracket, tab or the like. 
     Locking mechanism  3  includes a housing having an internal bore, an inlet port in fluid communication with the internal bore and the first brake line  300 , and an outlet port in fluid communication with the internal bore and a second brake line  200  for actuating the vehicle brake. A lid may be disposed on the housing and a reciprocating piston is movable within the internal bore. A locking lever  30  is coupled to the reciprocating piston for actuating the reciprocating piston. Preferably the locking lever is pivotally coupled to the housing lid. A portion of the locking lever may be in abutting contact with the reciprocating piston. 
     Locking lever  30  is moveable between a first, or unlocked position, wherein the hydraulic fluid can flow freely between the first brake line  300  and the second brake line  200  for engaging and disengaging the vehicle brake and a second, or locked position, wherein the hydraulic fluid is prevented from flowing between the first brake line  300  and the second brake line  200  for maintaining the vehicle brake in an engaged state. Operation of remote mounted locking mechanism  3  is as described for the embodiments discussed above. 
     Accordingly, while several embodiments of the present invention have been shown and described, it is obvious that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.