A MASTER CYLINDER BODY FOR AN HYDRAULIC MASTER CYLINDER FOR VEHICLES CONTROLLABLE BY HANDLEBARS

Abstract: A master cylinder body for an hydraulic master cylinder for vehicles controllable by handlebars, particularly for brake or clutch control, formed integrally and comprising a first portion (2) in which a chamber (3) which is to contain a piston (4) acting on a working fluid is formed, a second portion (10) for connection to a separate pipe for supplying the working fluid to the chamber through at lest one opening (110) in the first portion (2), the second portion extending transversely to an axis (20) of the chamber (3), and a third portion (8) for hinging a control lever (9), which portion (8) defines a pivoting plane (Y) for the control lever. An axis (Z) of the second portion (10) lies in the pivoting plane (Y) of the control lever.

Description: DESCRIPTION "A master cylinder body for an hydraulic master cylinder for vehicles controllable by handlebars" The present invention relates to a master cylinder body for an hydraulic master cylinder, and to an hydraulic master cylinder, for brakes and/or clutches of vehicles controllable by handlebars, such as motorcycles, motorcycle combinations, tricars and the like. More particularly, the invention relates to a master cylinder body for hydraulic master cylinders of the type in which a working-fluid reservoir separate from the master cylinder body is provided. As is known, vehicles controllable by handlebars, such as, for example, motorcycles, are normally provided with an hydraulic master cylinder for controlling the brake associated with the front wheel of the vehicle; that master cylinder is mounted on the handlebars on one side thereof, typically on the right-hand side relative to the direction of travel of the vehicle. A further hydraulic master cylinder may be provided in order to control the clutch and is mounted on the handlebars on the opposite side to the master cylinder for controlling the brake, typically on the left-hand side relative to the direction of travel . Known hydraulic master cylinders, particularly those of the type having a separate reservoir for working fluid, comprise a master cylinder body produced integrally by casting and comprising a first portion in which a chamber for accommodating a piston acting on a working fluid is formed, a second portion at the location of which a fork for hinging a piston-control lever is formed, and a third portion for securing the master cylinder body to the handlebars; the last-mentioned portion has a semicylindrical seat for accommodating the handlebars, which seat is to cooperate with a U-bolt having a complementary semicylindrical seat; by tightening the U-bolt on the master cylinder body by conventional means, such as screws, the handlebars are clamped firmly between the U-bolt and the master cylinder body. The master cylinder body also comprises a connector for the entry of the working fluid coming from the reservoir, which connector is formed by a flange which extends transversely to an axis of the chamber for accommodating the piston (for the sake of brevity referred to hereinafter as the axis of the master cylinder body) . When the master cylinder body is mounted on the handlebars, the axis of the master cylinder body is substantially parallel with the axis of the handlebars. The piston-control lever hinged to the fork of the master cylinder body lies in a plane defined by the axis of the handlebars and by the axis of the master cylinder body; that plane constitutes the plane of symmetry and pivoting of the control lever. Normally, in order to make the gripping of the control lever ergonomic for the driver of the vehicle, the master cylinder body is mounted on the handlebars in such a manner that the above-mentioned plane of symmetry and pivoting of the control lever is not horizontal but inclined downwards in the direction of travel of the vehicle, by an angle of, typically, approximately 15°. In addition, the master cylinder body is mounted on the handlebars in such a manner that the flange of the connector for the entry of fluid, which, as stated, lies transversely relative to the axis of the master cylinder body, extends upwards perpendicularly to a horizontal plane and therefore the master cylinder body is formed in such a manner that the flange of the connector for the entry of fluid is inclined by the complement of that angle relative to the plane in which the control lever lies and pivots. The portion for securing the master cylinder body to the handlebars also has a plane of connection to the associated horizontal U-bolt, which plane passes through the axis of the handlebars and is thus inclined by the above-mentioned angle relative to the plane in which the control lever lies and pivots. Owing to the relative positions of the various portions of which it is composed, a master cylinder body produced for coupling to the right-hand portion of the handlebars, thus typically for a brake master cylinder, cannot be used on the left-hand portion of the handlebars, that is to say, for a clutch master cylinder, without giving rise to an extremely obvious and unacceptable dissymmetry between the right-hand portion and the left-hand portion of the handlebars. If it is desired to use on the left-hand portion of the handlebars a master cylinder body produced for the right-hand portion, the master cylinder body would have to be turned over, with the result that the flange of the connector for the entry of fluid would extend downwards instead of ■ upwards. That, in addition to giving rise itself to a visible dissymmetry, would involve a modification to the hydraulic circuit for supplying fluid from the reservoir to the master cylinder body, relative to the analogous circuit provided on the right-hand portion of the handlebars . Therefore, in order not to come up against such unacceptable consequences, the prior art provides for the manufacture of master cylinder bodies having a different spatial form depending on the application for which they are intended, for right-hand or left-hand hydraulic master cylinders . This forces manufacturers to provide casting equipment (moulds) for the manufacture of the rough castings constituting the master cylinder bodies, equipment for working the rough castings and equipment for assembly, which equipment is distinct and specific for right-hand hydraulic master cylinders, for brakes, or for left-hand hydraulic master cylinders, for clutches. It will be appreciated that all this has a detrimental effect on the cost of equipment and the cost of management of the various parts . In view of the prior art described, an object of the present invention is to provide a master cylinder body which does not have the disadvantages associated with the known solutions . According to the present invention, that object is achieved by means of a master cylinder body according to claim 1. The characteristics and advantages of the present invention will become clear from the following detailed description, which is provided purely by way of example and which is in no way limiting, of some of its possible practical embodiments illustrated in the appended drawings in which: Figure 1 is an axonometric view of a master cylinder body according to a first possible practical embodiment of the present invention; Figure 2 is a top plan view of the master cylinder body of Figure 1, that is to say, from a delivery side; Figure 3 is a front view of the master cylinder body, in the direction of arrow III in Figure 2; Figure 4 is a sectional view of the master cylinder body taken on the plane IV-IV in Figure 2 ; Figure 5 is an axonometric view of a master cylinder body according to a second possible practical embodiment of the present invention; Figure 6 is an axonometric view of a master cylinder body according to a third possible practical embodiment of the present invention; Figure 7 is an axonometric view of a master cylinder body according to a fourth possible practical embodiment of the present invention; Figure 8 is an axonometric view of a master cylinder body according to a fifth possible practical embodiment of the present invention; Figure 9 is a front view of the master cylinder body in the direction of arrow IX in Figure 8, that is to say, from the delivery side; Figure 10 is a side view of the master cylinder body in the direction of arrow X in Figure 8, that is to say, from the side where the flange of the connector for the entry of fluid is arranged; and Figure 11 is a sectional view of the master cylinder body of Figure 8 taken on the plane XI-XI of Figure 10. Referring to the drawings, Figures 1 to 4 show a master cylinder body 1 according to a first possible practical embodiment of the present invention. The master cylinder body 1 comprises a generally cylindrical portion 2 which is internally hollow to form a chamber 3 for the accommodation and sliding of a piston 4 (shown with a dot-dash line in Figure 4) acting on a working fluid. A working fluid is to be understood as meaning any type of fluid suitable for use in braking systems or in clutch systems, for example for applications in vehicles controllable by handlebars . The portion 2 of the master cylinder body 1 has, at its first end, a connector 90 in which an opening 4 for the delivery of fluid and an opening 5 for carrying out bleeding operations on the hydraulic system are provided. The delivery opening 4 can be connected by conventional hydraulic connecting means to a brake or to a clutch. An axis 40 of the delivery opening 4 and an axis 50 of the bleeding opening 5 lie on a plane P passing through an axis 20 of the chamber 3 which also constitutes the axis of the portion 2. At the opposite end of the portion 2, the master cylinder body 1 comprises a portion 6 for securing to handlebars, which are shown with a dot-dash line in Figures 2, 3 and 4 in which they are identified by the reference 7, and a fork 8 for hinging a master cylinder- control lever, shown with a dot-dash line in Figure 2 and identified by the reference 9. The control lever is suitable for acting on a rod 100 integral with the piston which is to be accommodated in the chamber 3, so that, by pivoting the lever 9, it is possible to cause the piston to slide inside the chamber 3 so as to compress the fluid' in the hydraulic circuit downstream of the delivery opening 4. The portion 6 for securing to the handlebars 7 and the fork 8 for hinging the lever 9 both extend from the generally cylindrical portion 2 substantially transversely to the axis 20 thereof, although from substantially opposite sides. The portion 6 for securing the master cylinder body 1 to the handlebars 7 has a seat 11 for the handlebars 7. The seat 11 for the handlebars 7 is substantially semicylindrical, and a first pair of shoulders 12, the free surface of which lies in a plane indicated X in Figure 1, is formed on the two sides thereof. The two shoulders 12, each of which has a respective threaded hole 13 , are to cooperate with respective shoulders of a second pair of shoulders provided in a U- bolt which is to cooperate with the securing portion 6 of the master cylinder body 1 in order to secure the master cylinder body to the handlebars 7. Figures 3 and 4 show diagrammatically with a dot- dash line such a U-bolt 14 provided with a seat 16 for the handlebars, which seat 16 matches the seat 11 formed in the securing portion 6 and is therefore substantially semicylindrical. A pair of shoulders 15 suitable for cooperating with the shoulders 12 of the portion 6 for securing the master cylinder body 1 to the handlebars is provided on the sides of the seat 16. The U-bolt 14 is tightened by conventional means, such as screws 17, on the portion 6 in such a manner that the handlebars 7 are clamped firmly between the U-bolt 14 and the portion 6 of the master cylinder body 1. Provided in the fork 8 for hinging the lever 9 is a pair of superposed and aligned holes 18 which define a pivoting axis 80 for the lever 9. The pivoting axis 80 of the lever 9 is perpendicular to a plane Y passing through the axis 20 of the chamber 3 and through an axis 70 which represents the axis of the handlebars 7 when the master cylinder body 1 is mounted on the handlebars, that is to say, when the handlebars 7 are accommodated in the seat 11. The plane Y thus constitutes the plane of symmetry and pivoting of the control lever 9 . - The master cylinder body 1 is formed in such a manner that the plane Y is inclined by an angle α, typically 15°, relative to a plane X in which lies the free surface of the pair of shoulders 12 provided in the portion 6 for securing to the handlebars 7. A connecting flange 10 for the entry of working fluid extends from an intermediate position between the two ends of the generally cylindrical portion 2, transversely to the axis 20 thereof, and is connectable to a reservoir, separate from the- master cylinder body and not shown in the drawings, for supplying the working fluid to the chamber 3 of the master cylinder body 1 through an orifice 110 which opens into the chamber 3. An axis Z of the connector 10 is at right-angles to the axis 20 of the chamber 3 and lies in the plane Y defined above; therefore, the axis Z is inclined relative to the plane X by the angle α. In this first embodiment of the invention, the plane P, in which lie the axes 40 and 50 of the openings for delivery 4 and bleeding 5, respectively, passes through the axis 20 of the chamber 3 and forms with the plane Y an angle other than a right-angle. In particular, as will be appreciated from Figures 3 and 4, the plane P is at right-angles to the plane X. The master cylinder body 1 can be used equally well for brake master cylinders, therefore being mounted on the right-hand portion of the handlebars, or for clutch master cylinders, being mounted on the left-hand portion of the handlebars. In the first case, the master cylinder body 1 is mounted on the right-hand portion of the handlebars in, such a manner that the handlebar seat 11 of the portion 6 for securing to the handlebars has its concavity facing upwards, with the plane X, in which the axis of the handlebars lies, arranged horizontally. The plane Y in which the control lever 9 lies and pivots is therefore inclined by the desired angle α relative to the horizontal plane, so that the control lever is directed slightly downwards in the direction of travel of the vehicle (direction of arrow M in Figure 3) . In the second case, the master cylinder body 1 is mounted on the left-hand portion of the handlebars, turned upside down and rotated downwards still in the direction of travel of the vehicle, that is to say, with the concavity of the seat 11 for the handlebars facing downwards, with the plane X no longer arranged horizontally but rotated in such a manner that the plane Y in which the control lever 9 lies and pivots is again rotated downwards by the desired angle relative to the horizontal plane. Owing to the fact that the axis Z of the connector 10 for the entry of fluid lies in the plane Y, the master cylinder body 1 is suitable for being mounted on the handlebars either on the right or on the left without giving rise to undesired dissymmetry, above all in the two hydraulic circuits. The only visible difference in the use of two identical master cylinder bodies of the type shown and described, as a brake master cylinder and as a clutch master cylinder, resides in the fact that, in the one case, the U-bolt 14 is arranged above the handlebars while, in the other case, the U-bolt 14 is arranged substantially below the handlebars. This slight dissymmetry is, however, regarded as acceptable. Figure 5 is an axonometric view of a master cylinder body 1' in accordance with a second possible practical embodiment of the present invention. Compared with the previous embodiment, the master cylinder body 1' has a portion 60 for securing to the handlebars of the vehicle which has been modified in such a manner that it has a substantially semicylindrical seat 11' for the handlebars, with the convexity facing the axis 20 of the chamber 3 for the piston, which chamber 3 is formed inside the generally cylindrical portion 2 of the master cylinder body. In more detail, the portion 60 for securing to the handlebars has, on the sides of the seat 11' for the handlebars, a pair of shoulders 12', each having a respective threaded hole 13 and being suitable for cooperating with a U-bolt which is in itself identical to the U-bolt 14 of Figures 3 and 4. The free surface of the shoulders 12' lies in a plane X' at right-angles to the plane Y passing through the axis 20, through the axis Z of the connector 10 and constituting the plane of symmetry and pivoting of the control lever. The portion 60 for securing to the handlebars is also symmetrical relative to the plane Y. A further difference from the previous embodiment is that a connector 90', in which the delivery opening 4 and the bleeding opening 5 are formed, is rotated in such a manner that a plane P' passing through axes 40' and 50' of the delivery opening 4 and the bleeding opening 5, respectively, is at right-angles to the plane Y, that is to say, parallel with the plane X' . Thus, the master cylinder body 1' is completely symmetrical relative to the plane Y. In order to be mounted on the handlebars, the master cylinder body 1' is brought up to the handlebars from the front relative to the direction of travel of the vehicle, taking care to orient the master cylinder body in such a manner that the plane Y is inclined by the desired angle α relative to a horizontal plane. In particular, Figure 5 shows the master cylinder body in the position suitable for being mounted on the right-hand portion of the handlebars; in order to mount it on the left-hand portion, it is necessary only to rotate the master cylinder body through 180° about the axis Z . The master cylinder body 1' according to this second possible practical embodiment has a further advantage over the previous embodiment: owing to the different form of the portion 60 for securing to the handlebars, the master cylinder body 1' can be mounted equally well on the right-hand side or on the left-hand side of the handlebars without any visible dissymmetry: the U-bolt for tightening the master cylinder body 1' on the handlebars is in both cases positioned on the inner side of the handlebars, in the direction of travel of the vehicle . Furthermore, being completely symmetrical relative to a plane, the plane Y, the master cylinder body is easier to manufacture because the mould for producing the rough casting can advantageously be formed from only two portions . However, it will be noted that, by abandoning this last advantage in terms of the process for the manufacture of the master cylinder body, it would be possible to manufacture the master cylinder body 1' with a connector 90 like that shown in Figures 1 to 4 , that is to say, with the plane P not at right-angles to the plane Y. It will be appreciated that the master cylinder body would in that case no longer be entirely symmetrical relative to the plane Y. Figure 6 is an axonometric view of a master cylinder body 1" according to a third possible embodiment of the present invention. As in the previous embodiment, the master cylinder body 1" is completely symmetrical relative to the plane Y in which lie the axis 20 of the chamber 3 for the piston and the axis Z of the connector 10 for the entry of fluid. The difference between the master cylinder body 1" and the master cylinder body of Figure 5 resides in the fact that a connector 90", which is arranged at the end of the portion 2 and in which the fluid-delivery opening 4 and the bleeding opening 5 are formed, is rotated in such a manner that the two axes 40" and 50" of the openings 4 and 5, respectively, lie in the plane of symmetry Y of the master cylinder body 1" . Owing to the fact that it is again completely symmetrical relative to a plane, the plane Y, the master cylinder body 1" has substantially the same advantages as the master cylinder body 1' in the previous embodiment. The mounting of the master cylinder body 1" on the right-hand portion or left-hand portion of the handlebars is carried out in a manner entirely analogous to that described in relation to the master cylinder body 1' of Figure 5. Figure 7 is an axonometric view of a master cylinder body 1'" according to a fourth possible practical embodiment of the present invention. As will be appreciated from a comparison with the master cylinder body 1' of Figure 5, the master cylinder body 1'" is provided with a connector 10'" for the entry of fluid into the chamber 3 for the piston, which connector 10'" again extends along the axis Z lying in the plane Y, but in the opposite direction to that of the connector 10 of the master cylinder body 1' ; in other words, the connector 10'" extends at right- ' angles to the axis 20 of the chamber 3 for the piston from the same side as the portion 6 for securing to the handlebars, instead of from the side where the fork 8 for hinging the control lever is arranged. The master cylinder body 1'" is again completely symmetrical relative to a plane, represented by the plane Y in which lie the axis 20 of the chamber 3 for the piston and the axis Z of the connector 10'" and which constitutes the plane of symmetry and pivoting of the control lever. Thus, the master cylinder body 1'" has substantially the same advantages as the master cylinder bodies 1' and 1" of Figures 5 and 6. In this case too, in order to mount the master cylinder body 1'" on the right-hand or left-hand portion of the handlebars, the procedure is analogous to that described in relation to Figures 5 and 6. Finally, Figures 8 to 11 show a master cylinder body 1"" according to a fifth possible embodiment of the present invention. The master cylinder body 1"" is substantially analogous to the master cylinder body 1' of Figure 5 and to the master cylinder body 1" of Figure 6, except that one end of the generally cylindrical portion 2 is provided with a connector 90"" which has only one opening 4"", or delivery opening, to which a fluid- delivery pipe is connectable. The delivery opening 4"" has an axis coinciding with the axis 20 of the chamber 3 for the piston. The master cylinder body 1"" is also completely symmetrical relative to a plane represented by the plane Y in which the axis 20 and the axis Z lie and in which the control lever hinged to the fork 8 lies and pivots. The mounting of the master cylinder body 1"" on the right-hand or left-hand portion of the handlebars is carried out in the same manner as that described in relation to Figures 5, 6 and 7. It will be appreciated that the person skilled in the art could readily provide further variants and/or additions to what has been described and illustrated above without departing from the protective scope of the present invention defined in the appended claims. For example, the bleeding opening could be provided in a connector, distinct from the connector in which the delivery opening is provided, extending from the portion 2 of the master cylinder body transversely to the axis 20 of the chamber 3 for the piston. In that case, in order to preserve symmetry when mounting on the right-hand and left-hand portions of the handlebars, an axis of the connector in which the bleeding opening is provided will likewise have to lie in the plane Y in which the axis of the connector for the entry of working fluid lies.

Claims: CLAIMS 1. A master cylinder body for an hydraulic master cylinder for vehicles controllable by handlebars, particularly for brake or clutch control, formed integrally and comprising a first portion (2) in which a chamber (3) which is to contain a piston (4) acting on a working fluid is formed, a second portion (10) for connection to a separate pipe for supplying the working fluid to the chamber through at least one opening (110) in the first portion (2) , the second portion extending transversely to an axis (20) of the chamber (3) , and a third portion (8) for hinging a control lever (9), which portion (8) defines a pivoting plane (Y) for the control lever, characterized in that an axis (Z) of the second portion (10) lies in the pivoting plane (Y) of the control lever. 2. A master cylinder body according to claim 1, comprising, integrally with the first (2) , second (10) and third portion (8) , a fourth portion (6; 60) for mounting the master cylinder body on vehicle handlebars, the fourth portion having a seat (11; 11') for accommodating at least one handlebar portion, wherein, when the at least one handlebar portion is accommodated in the seat (11; 11'), an axis (70) of the handlebars lies in the pivoting plane (Y) of the control lever. 3. A master cylinder body according to claim 2, wherein the fourth portion (6) comprises, on the sides of the seat (11) for the handlebars, a pair of shoulders (12) which are to cooperate with a corresponding pair of shoulders (15) of a U-bolt (14) which can be associated with the fourth portion (6) of the master cylinder body by tightening in order to clamp the handlebars firmly, the shoulders (12) of the fourth portion (6) having a free surface which defines a plane (X) which forms an angle (α) with the pivoting plane (Y) of the control lever (9) . 4. A master cylinder body according to claim 3, wherein the angle ( ) is approximately 15° . 5. A master cylinder body according to claim 2, wherein the fourth portion (60) comprises, on the sides of the seat (11') for the handlebars, a pair of shoulders (12') which are to cooperate with a corresponding pair of shoulders (15) of a U-bolt (14) which can be associated with the fourth portion (60) of the master cylinder body by tightening in order to clamp the handlebars firmly, the shoulders (12') of the fourth portion (60) having a free surface which defines a plane (X') at right-angles to the pivoting plane (Y) of the control lever (9) . 6. A master cylinder body according to claim 5, wherein the pivoting plane (Y) of the control lever is a plane of symmetry of the master cylinder body. 7. A master cylinder body according to claim 6, wherein the first portion (2) terminates, at one end, with an outlet connector (90; 90'; 90"; 90"") which has at least one opening (4; 4"") for delivering the working fluid acted on by the piston and which can be connected to a delivery pipe. 8. A master cylinder body according to claim 7, wherein the delivery opening (4) has an axis (40') which lies in a plane (P) passing through the axis (20) of the chamber (3) and at right-angles to the pivoting plane (Y) of the control lever. 9. A master cylinder body according to claim 7, wherein the delivery opening (4; 4"") has an axis (40"; 20) parallel with the axis (20) of the chamber (3) and lying in the pivoting plane (Y) of the control lever. 10. A master cylinder body according to claim 9, wherein the axis (20) of the delivery opening (4"") coincides with the axis (20) of the chamber (3) . 11. A master cylinder body according to claim 8, wherein the outlet connector (90') also has an opening (5) for bleeding the hydraulic circuit, the bleeding opening having an axis (50') parallel with the axis (40') of the delivery opening (4) and lying in the plane (P) at right-angles to the pivoting plane (Y) of the control lever . 12. A master cylinder body according to claim 8, wherein the outlet connector (90") also has an opening (5) for bleeding the hydraulic circuit, the bleeding opening having an axis (50") parallel with the axis (40) of the delivery opening (4) and likewise lying in the pivoting plane (Y) of the control lever. 13. An hydraulic master cylinder for a brake or clutch of vehicles controllable by handlebars, comprising a master cylinder body and a reservoir which can be connected hydraulically to the master cylinder body by means of a connector for supplying a working fluid to the master cylinder body, characterized in that the master cylinder body is formed in accordance with any one of the preceding claims, so that it can be mounted on the handlebars of a vehicle equally well on the right or on the left in the direction of travel of the vehicle.

Inventors: LAVEZZI ROBERTO, LAVEZZI, ROBERTO
Applicants: FRENI BREMBO SPA, LAVEZZI ROBERTO, FRENI BREMBO S.P.A., LAVEZZI, ROBERTO
Application year: 2000
Main classification: B62L3
IPC codes: B60T11, B62L3