HANDLEBAR MOUNTED MASTER CYLINDER

Abstract: A handlebar cowl assembly for a motor scooter incorporates an integral hydraulicmaster cylinder 59 suitable for actuating a front brake. Cowl 53 is mounted on handlebar 51 and carries the master cylinder within a bore 57 of the cowl. A hand lever 71 pivoted on the cowl at 72 has a projection 73 which engages piston 74 to operate the master cylinder and force fluid along supply pipe 76. A shoulder 77 restrains the master cylinder against movement further into the bore. A strap 64, which hold a reservoir connection (not shown) to the master cylinder locates in an enlarged portion of the bore and restrains the master cylinder against falling out of the bore towards hand lever 71.

Description: HANDLEBAR MOUNTED MASTER CYLINDER This invention relates to handlebar mounted master cylinders particularly though not exclusively for motor scooters. Unlike motor cycles, the handlebars of motor scooters are usually housed in a cowl. The cowl is generally aerodynamically shaped and houses the headlamp, speedometer and operating cables for the front brake, clutch, gearchange and accelerator. The cowl protects the cables especially from accident damage and provides a neat uncluttered appearance to the scooter. Upper and lower cowl parts, usually die cast in an aluminium alloy are fixed about the handlebar by setscrews. It has been proposed to provide a hydraulically operable front disc brake for a motor scooter and one problem has been to locate the master cylinder on the handlebar whilst retaining the traditional neat and uncluttered appearance of the scooter. According to the present invention there is provided a handlebar cowl assembly for a motor cycle, wherein the cowl assembly comprises a cowl member, a master cylinder housed in a bore of the cowl member, a hand lever pivoted to the cowl member to thrust on a piston of the master cylinder and a fluid supply in fluid communication with said master cylinder. Such an assembly retains the traditional appearance of a scooter whilst protecting the precision parts of the master cylinder against damage. The fluid supply for the master cylinder may be a reservoir formed as a plastics moulding which can easily be adapted to the profile of the handlebar cowl or may be cast as part of the cowl itself. Preferably the master cylinder comprises a tubular steel body forming an insert in the cowl assembly and defining the master cylinder bore. A tubular steel body allows the master cylinder to have the strength and resistance to wear required whilst allowing the cowl to provide the supporting structure for the cylinder. The master cylinder may be installed and replaced as an insert so simplifying assembly and service replacement. Thus the use of relatively expensive steel is kept to a minimum as compared with the die cast aluminium alloy of the cowl. This construction is also lighter than would be possible if a conventional hand operated master cylinder were attached to the cowl. Preferably the handlebar cowl assembly further comprises a strap surrounding the master cylinder to hold a reservoir connection against a passage leading to the interior of the master cylinder, the bore in the cowl member being stepped to receive the strap such that the strap locates the master cylinder axially within the bore against withdrawal against the direction of thrust on the piston. Preferably the reservoir connection is spigotted into the master cylinder to provide positive location, axially of the master cylinder between the master cylinder and the strap. To enable the master cylinder to be assembled within the cowl, the cowl may be formed in two parts, split substantially along a Lraflsverse plane of the master cylinder bore. The invention will now be described by way of example only dild wjlji reference to the accompanying drawings in which: Figure 1 is a view from the front of a cowled handlebar incorporlting the invention; Figure 2 is a plan view of the cowled handlebar of figure 1; Figure 3 is a transverse section through the handlebar of figure 1 on line A-A; Figure 4 is a axial section through figure 2 on line B-B and not showing the hand lever; Figure 5 is a view corresponding to figure 3, showing an alternative embodiment; Figure 6 is a section on line VI-VI of figure 5, showing the master cylinder itself in full; Figure 7 is a side elevation of the master cylinder, showing its reservoir connection in section; and Figure 8 is a plan view of the master cylinder of figure 7. Figures 1 to 4 show one end of a motor cycle handlebar 11 having he usual rubber hand grip 12. A cowl 13 for the h.llldlebar extends from the hand grip 12 over the central portion of the handlebar to the other hand grip (not shown). On the rear side of the cowl 13 is a switch panel 14 secured by a screw 15 and having thumb switches 16 for the operation of electrical equipment provided on the scooter. The front side of the cowl 13 has a bore 17 opening into the cowl interior and housing a master cylinder 18. The master cylinder has a tubular steel body 19 retained in the cowl by an abutment 21 of the bore 17 and a circlip 11. A piston 23 is urged outwardly in the master cylinder bore by a coil spring 24 and has the usual pressure seal 25, atmospheric seal 26 and dust seal 27. The usual hand lever 28, pivoted to the cowl by bolt 29, acts directly on the master cylinder piston 23 and is hence urged to the return position by the spring 24. A grub screw 31 is provided to adjust the rest position of the hand lever 28. A fluid hose 32 terminates in an adaptor 30 which is retained in a tubular extension 33 of the master cylinder by a roll pin 34 located in a groove of the hose end. An O-ring 35 seals the adaptor in the extension 33. The hose 32 is intended for connection to a front brake actuator of the scooter but could be alternatively connected to an actuator for the rear brake or to a release mechanism of the scooter drive clutch. The usual fluid reservoir 36 is mounted on the cowl immediately above the master cylinder and communicates to the interior of the master cylinder 18 by the usual passages (not shown). Operation of the master cylinder is achieved by squeezing the hand lever 28 towards the grip 12 and thus generating pressure in the master cylinder as the piston 23 is urged into the master cylinder bore. A second embodiment will now be described with reference to figures 5 to 8. Figures 5 and 6 show one end of a motor cycle handlebar 51 having the usual rubber hand grip 52. A cowl 53 for the handlebar extends from the hand grip 52 over the central portion of the handlebar to the other hand grip (not shown). On the rear side of the cowl 53 is a switch panel 54 secured by a screw 55 and having thumb switches 56 for operation of the electrical equipment provided on the motor cycle. The front side of the cowl 53 has a bore 57 opening into the cowl interior and housing a master cylinder 58. The cowl is formed in two parts divided as shown in figure 6 to allow radial access into the bore 57 as best seen in figure 6. The master cylinder has a tubular steel body 59 best seen in figures 7 and 8. A reservoir connection 61 communicates with a passage 62 in the wall of the master cylinder, leading to the interior of the master cylinder to supply fluid thereto. Connection 61 is spigotted at 63 to the master cylinder and is held securely against the face of the master cylinder by a strap 64 which at one side 65 is integral with the connection 61 and after passing round the master cylinder is connected to the connection 61 by passing through an aperture 66 with which it locks positively due for example to serrations on the outer face of the strap and a co-operating formation in the aperture 66. As best seen in figure 5, strap 64 engages in an enlarged part of the bore 57 in such a way that the strap is constrained against movement axially of the master cylinder in either direction. Because of the spigotted connection 63 and the tightness of the strap 64, the master cylinder is similarly constrained. As best seen in figure 6, bore 57 opens on its upper side into an enlarged chamber 67 which houses the connection 61 and through which a connection hose 68 leads to a reservoir or supply tank. The enlarged chamber 67 also houses the free end of the strap 64 which has passed through the aperture 66. It is in order to deflect the strap against the wall of chamber 67 as shown. Strap 64 also incorporates a location pip 69 which engages in a corresponding recess in the bore 57 in order to hold the strap and thus the master cylinder against rotation. A hydraulic seal 7t0 is arranged around the spigot 63 in order to provide a fluid tight seal between the connection 61 and the master cylinder. A hand-operable brake lever 71 is pivotted at 72 to the cowl and has a projection 73 arranged to engage directly against a piston 74 of the master cylinder 58. The master cylinder also has a brake connection 75 leading through brake tube 76 to a brake to be actuated. The interior of the master cylinder and other features not described in detail correspond to like features in the embodiment of figures 1 to 4. To operate the brake of figures 5 to 8, an operative grips the handlebar grip 52 and brake lever 71 to bring the lever 71 towards the hand grip 52, thereby pivotting the handle 71 and causing projection 73 to bear against piston 74. This causes the piston to be displaced within the master cylinder and thus supplies hydraulic fluid pressure through tube 76 towards a brake. This thrust on the piston tends to urge the master cylinder further into its bore away from the hand lever and as the force involved may be substantial, the master cylinder has a shoulder 77 which engages against a corresponding shoulder within the bore. The installation of strap 64 and its associated constraints are sufficiently flexible to ensure that the axial load applied to the master cylinder during brake actuation is reacted against the rigid supporting shoulder 77. The strap 64 and its associated enlarged part of the bore 57 constrains the master cylinder against accidental rotation and also against falling out of its bore in a direction towards the handle or at least retreating towards the lever 71 in such a way as to require excessive hand lever movement to actuate the brake. In this way, the provision of strap 64 obviates the requirement for additional mechanical constraint by means of which the master cylinder might retreat accidentally along the bore. In an alternative to the embodiment of figures 1 to 4, the master cylinder piston and seals operate in a bore of the cowl without the interposition of the tubular steel body. Such a construction is less expensive but requires high accuracy machining and finishing of the bore of the cowl. Furthermore the master cylinder is not replaceable as an insert. The kind of motor cycle to which the cowl and master cylinder assembly is most appropriate is a motor scooter which is normally provided with a cowl of this nature and which may require a hydraulic master cylinder within the cowl The master cylinder is intended primarily for actuation of a front disc brake but could be connected to a rear brake or used for clutch actuation.

Claims: CLAIMS 1. A handlebar cowl assembly for a motor cycle, comprising a cowl member (3 or 53) and a hand lever (28 or 71) pivoted to the cowl member, characterised by a master cylinder (19 or 59) housed in a bore (15 or 57) of the cowl member, the hand lever being arranged to thrust on a piston (23 or 74) of the master cylinder and a fluid supply (36 or 68) in fluid communication with said master cylinder. 2. An assembly according to claim 1, characterised in that said master cylinder comprises a tubular steel body forming an insert in the cowl assembly and defining the master cylinder bore. 3. An assembly according to claim 2, characterised in that the tubular steel body includes an axial tubular outlet port opening to the interior of the cowl and for connection to a wheel brake of the motor cycle. 4. An assembly according to any one of the preceding claims characterised by the provision of a strap (64) surrounding the master cylinder (59) to hold a reservoir connection (61) against a passage (62) leading to the interior of the master cylinder, the bore (57) in the cowl member being stepped to receive the strap such that the strap locates the master cylinder axially within the bore against withdrawal against the direction of thrust on the piston. 5. An assembly according to claim 4 characterised in that the reservoir connection is spigotted (at 63) into the master cylinder to provide positive location, axially of the master cylinder between the master cylinder and the strap. 6. An assembly according to claim 4 or claim 5, characterised in that to enable the master cylinder to be assembled within the cowl, the cowl is formed in two parts (53, 53 in figure 6 split substantially along a transverse plane of the master cylinder bore.

Inventors: DAWKES, ANDREW PETER
Applicants: AUTOMOTIVE PRODUCTS PUBLIC LIMITED COMPANY
Application year: 1983
Main classification: B62L3
IPC codes: B60T11, B62L3