Combined brake system for vehicles

Abstract

The invention refers to a Combined Brake System, CBS, for vehicles provided with two independent brake actuators, preferably for motorcycles. The system comprises: a plunger displaceable inside a housing between first and second end axial position, and a valve member axially displaceable relative to the plunger, and a first spring pressing on the plunger, such that displacement of the plunger from the first position towards the second position, is carried out against the force of the first spring, and displacement of the plunger from the second position to the first position, is assisted by the first spring. In the first axial position of the plunger, the valve member is open and a front master inlet port and a front caliper outlet port, are fluidly communicated, and in the second axial position of the plunger, the valve member is closed and the front master inlet port and the front caliper outlet port are fluidly isolated.

Description

[0001] COMBINED BRAKE SYSTEM FOR VEHICLES

[0002] DESCRIPTION

[0003] TECHNICAL FIELD

[0004] The present invention relates to a Combined Brake System, CBS, for vehicles provided with two independent brake actuators, preferably for motorcycles.

[0005] An object of the invention is the provision of a Combined Brake System, in which the maximum pressure at a front caliper is only influenced by the front lever piston stroke, such that there is no need to replace the front caliper for one of higher braking capacity or to replace the CBS, when it is desirable to increase the braking capacity in the front wheel.

[0006] BACKGROUND OF THE INVENTION

[0007] A combined braking system (CBS), also called linked braking system (LBS), is a system for linking front and rear brakes in vehicles provided with two independent brake actuators, for example motorcycles, such that, the rider's action of depressing one of the brake levers applies both, to front and rear brakes. The amount of each brake force applied may be determined by a proportional control valve.

[0008] The CBS is designed for safety without ABS, for example for scooters, to prevent a wheel from locking up, thus, preventing losing control of the bike.

[0009] Experienced riders have better control over the intensity and distribution of braking, but the CBS system takes care of this on its own. To avoid locking the front wheel, the CBS brake ensures that, although we only act on one of the two brakes on the bike, braking force is also applied to the other wheel, albeit at a lower intensity, to make the action more effective. In other words, even if we brake only with the rear master to act on the rear wheel, the front brake will also be activated.

[0010] The CBS system is designed in such a way as to avoid transferring too much weight to the front wheel, as this could leave the rear wheel with little support and cause it to lock up. And likewise, to act on the rear brake so that the braking intensity is greater - also acting on the front brake - thus reducing the braking distance considerably and minimizing the risk of an accident. One of the problems with known CBS systems, is the physical limitation of the piston stroke when the front wheel lever is actuated. For example, if the front wheel lever is replaced by one with higher pressure capacity in order to improve the braking capacity in the front wheel, the CBS cannot operate properly, hence the CBS must also be replaced by one of larger capacity.

[0011] DESCRIPTION OF THE INVENTION

[0012] The invention is defined in the attached independent claim, and satisfactorily solves the above-described drawbacks of the prior art, by the provision of a Combined Brake System, comprising:

[0013] - an elongated housing extending along an axis,

[0014] - a plunger displaceable inside the housing between two end positions, namely a first axial position and a second axial position,

[0015] - a front chamber formed in the housing at a first end of the plunger,

[0016] - a middle chamber formed in the housing at a middle zone of the plunger,

[0017] - a rear chamber formed in the housing at a second end of the plunger, wherein the rear chamber is fluidly isolated from the front and middle chambers,

[0018] - a rear master inlet port and optionally a rear caliper outlet port, both fluidly communicated with the rear chamber, both, in the first and in the second axial positions of the plunger,

[0019] - a front master inlet port communicated with the middle chamber,

[0020] - a front caliper outlet port communicated with the front chamber,

[0021] - an internal passage for communicating the middle chamber with the front chamber,

[0022] - a first spring, for example a compression spring, placed in the front chamber and pressing on the first end of the plunger, such that displacement of the plunger from the first position towards the second position, is carried out against the force of the first spring, and displacement of the plunger from the second position to the first position, is assisted by the first spring, and

[0023] - a valve member axially displaceable relative to the plunger and configured for opening and closing the internal passage.

[0024] The above-described system is configured such that, the volume of the rear chamber increases and the volume of the front chamber decreases, as the plunger moves from the first position towards the second position, that is, a pressure in the rear chamber is applied to the front chamber by means of the plunger, and as this pressure overcomes the force exerted by the first spring, the plunger moves from the first position towards the second position, thus, increasing the pressure in the front chamber. Furthermore, the system is configured such that in the first axial position of the plunger, the valve member is open, and the front master inlet port and the front caliper outlet port are fluidly communicated through the internal passage, and in the second axial position of the plunger, the valve member is closed, and the front master inlet port and the front caliper outlet port are fluidly isolated.

[0025] The valve member is accommodated inside the plunger, and a section of the internal passage is formed in between the valve member and the plunger, such that, in its closed position the valve member is in contact with the plunger at said section, and in its open position, the valve member is distanced from the plunger at that section of the internal passage.

[0026] The internal passage extends internally through the valve member, and wherein a section of the valve member and a section of the internal passage closest to the middle chamber, are wider than a section of the valve member and a section of the internal passage closest to the front chamber.

[0027] The system further comprises a second spring placed inside the plunger, in between the plunger and the valve member, such that the second spring presses the valve member towards the middle chamber.

[0028] A tubular chamber is formed between the plunger and the housing at a middle section of the plunger, wherein this tubular chamber is in fluid communication with the middle chamber, such that the front master inlet port is communicated with the front caliper outlet port, through the tubular chamber, the middle chamber and the internal passage, when the valve member is open.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To complete the description and in order to provide a better understanding of the invention, a set of drawings is provided. These drawings form an integral part of the description and illustrate embodiments of the invention, which should not be interpreted as restricting the scope of the invention, but just as examples of how the invention can be carried out. The drawings comprise the following figures:

[0031] Figure 1 shows the CBS system of the invention, wherein the connections with front and rear calipers and front and rear master levers, are indicated by arrows.

[0032] Figures 2 to 5.- show a longitudinal cross-sectional view of the CBS system, in the first position (Figure 2), in an intermediate position (Figure 3), in a second position with the valve closed (Figure 4), and in the second position with the valve open (Figure 5).

[0033] Figures 6 to 1 1.- show several graphs illustrating the operation of the CBS system of the invention in all possible combination of activation of the front and rear levers over time: only front (Figures 6A, 6B), only rear (Figures 7A, 7B), first front then rear (Figures 8A, 8B), first rear then front (Figures 9A, 9B), rear while front (Figures 10A, 10B) and front while rear (Figures 11 A, 1 1 B). The upper figures (6A - 1 1 A) represent to the activation of the front and / or rear brake levers, whereas the bottom figures (6B - 1 1 B) represent the pressure applied to the front and / or rear calipers in response to the activation of the front and / or rear brake levers. Marks 1 and 2, are indicated by dotted lines and encircled numbers 1 and 2.

[0034] Figure 12.- shows an alternative embodiment of the invention, wherein as in the case of Figure 1 , the connections between front and rear calipers and front and rear master levers, are indicated by arrows.

[0035] PREFERRED EMBODIMENTS OF THE INVENTION

[0036] Figures 1 to 5 show the CBS system (1 ) of the invention, comprising: an elongated housing (2) extending along an axis (X), and a plunger (3) axially displaceable inside the housing (2) between two end positions, namely a first axial position shown in Figure 1 and a second axial position, shown in Figure 4.

[0037] Additionally, the system (1 ) has a front chamber (4) formed in the housing (2) at a first end (3a) of the plunger (3), a middle chamber (5) formed in the housing (2) at a middle zone of the plunger (3), and a rear chamber (6) formed in the housing (2) at a second end (3b) of the plunger (3), wherein the rear chamber (6) is fluidly isolated from the front and middle chambers (4, 5).

[0038] A first spring (13), preferably a compression spring, is housed in the front chamber (4) and it is adapted for contacting on an internal wall of the housing (2) and for pressing on the first end (3a) of the plunger (3), such that displacement of the plunger from the first position towards the second position, is carried out against the force of the first spring (13), and displacement of the plunger (3) from the second position to the first position, is assisted by the first spring (13).

[0039] The system (1 ) has a rear master inlet port (7) and a rear caliper outlet port (23), both fluidly communicated with the rear chamber (6) in the first and in the second axial positions of the plunger (3). As shown in Figure 1 , the rear master inlet port (7) is meant to be connected to a rear master lever (9), and the rear caliper outlet port (23) is meant to be connected to a rear caliper (10), such that in use, when the system is installed in a vehicle provided with two independent brake actuators, for example a motorcycle, activation of the rear master lever (9) would operate the rear caliper (10) to brake the rear wheel of the motorcycle. In the embodiment shown in the figures, the rear master inlet port (7) and the rear caliper outlet port (23) are placed opposite each other.

[0040] Furthermore, the system (1 ) has a front master inlet port (1 1 ) communicated with the middle chamber (5), and a front caliper outlet port (12) communicated with the front chamber (4). The front master inlet port (1 1 ) is meant to be connected to a front master lever (8).

[0041] In the embodiment illustrated in the figures, the rear master lever (9) and front master lever (8), are hand operated levers. Alternatively, in other embodiments of the invention, any of these levers may be a foot operated lever.

[0042] Hydraulic pressure in the rear chamber (6) is applied to the rear end (3b) of the plunger (3) in an opposite direction of the force exerted by the first spring (13), and when that pressure overcomes the force of the first spring (13), the plunger (3) moves towards the second position, thus, increasing the volume of the rear chamber (6) and reducing the volume of the first chamber (4), thus, transmitting pressure to the front caliper outlet port (12).

[0043] The system (1 ) further includes a valve member (14) accommodated inside the plunger (3), and axially displaceable relative to the plunger (3). A second spring (15) is placed inside the plunger and in between the plunger (3) and the valve member (14), in a way that the second spring (15) presses the valve member (14) towards the middle chamber (5).

[0044] A tubular chamber (17) is formed between the plunger (3) and the housing (2) at a middle section of the plunger, and this tubular chamber (17) is in fluid communication with the middle chamber (5). A front section (3c) of the plunger (3) extending front the first end (3a) is sealed with the housing internal surface by means of a first O-ring (18), and a rear section (3d) of the plunger (3) extending front the second end (3b) is sealed with the housing internal surface by means of a second O-ring (19). The tubular chamber (17) is formed in between the front and rear sections (3c, 3d) of the plunger (3).

[0045] An internal passage (16) is formed communicating the middle chamber (5) with the front chamber (4), hence, communicating the front master inlet port (1 1 ) with the front caliper outlet port (12). The internal passage (16) extends internally through the valve member (14), and a section (14a) of the valve member and a section (16a) of the internal passage (16) closest to the middle chamber (5), are wider than a section (14b) of the valve member and a section (16b) of the internal passage (16) closest to the front chamber (4). The section (14a) is sealed with the plunger (3) by means of the third O-ring (20), and the section (14b) of the valve member (14) is sealed with the plunger (3) by means of a fourth O-ring (21 ).

[0046] The O-rings (18, 19, 20, 21 ) may be implemented as O-ring, X-ring or Lip-seal, referring to the shape of its cross-sectional area.

[0047] There is an interstice (26) formed in between the valve member (14) and the plunger (3), communicating the passage (16) with the cavity in which the second spring (15) is located.

[0048] The valve member (14) is configured for opening and closing the internal passage (16). A section of the internal passage (16) is formed in between a head (25) of the valve member (14) and the plunger (3), such that, in its closed position the head (25) is in contact with the plunger (3) at that section, and in its open position, the head (25) of the valve member (14) is distanced from the plunger (3) at that section of the internal passage, thus, allowing fluid circulation.

[0049] The system (1 ) has pin (22) arranged orthogonally to the axis (X) and attached to the housing (2). The pin (22) passes across the middle chamber (5) formed in plunger (3), such that the two end axial positions of the plunger (3), are defined by the contact of the plunger (3) with the pin (22). In the first position (Figure 2) the plunger (3) contact on one side of the pin (22) pressed by the first spring (13), and in the second position (Figure 4) the plunger (3) contact on an opposite side of the pin (22) due to hydraulic pressure in the rear chamber (6).

[0050] With the above-described configuration and arrangement of components, the operation of the CBS system (1 ), that is, when the system is installed in a motorcycle as shown in Figure 1 , is as follows:

[0051] When only the front master lever (8) is actuated, the plunger (3) is in its first axial position and the valve member (14) is open, so the front master inlet port (1 1 ) and the front caliper outlet port (12), are fluidly communicated through the tubular chamber (17), the middle chamber (5) and the internal passage (16), so that fluid flows directly to the front caliper (24).

[0052] When only the rear master lever (9) is actuated, hydraulic pressure is applied directly to the rear chamber (6) and to the rear caliper (10). Hydraulic pressure at the rear chamber (6) is also applied on the second end (3b) of the plunger (3), and when this pressure is larger than the force exerted by the first spring (13), the plunger (3) moves towards the left-hand side of the figures compressing the first spring (13) until the plunger (3) contacts with the head (25) of the valve, as shown in the intermediate position of Figure 3, thereby closing the valve member by closing passage (16). At that situation, the plunger (3) pushes the valve member (14) towards the second axial position.

[0053] When the passage (16) is closed, the front master inlet port (1 1 ) and the front caliper outlet port (12) are fluidly isolated, and the plunger (3) pressures the front caliper (24) through the front chamber (4). As it can be appreciated in the figures, the separation distance between the plunger (3) and the valve member's head (25), determines the delay to apply pressure to the front caliper (24) due to the pressure at the rear chamber (6).

[0054] The plunger (3) reaches its second axial position when it contacts the pin (22) (Figure 4). In the second axial position of the plunger (3), the pressure in the front caliper (24) due to the activation of the rear master lever (9) cannot increase any further, so this second axial position of the plunger (3) determines the maximum pressure that can be applied to the front caliper (24) due to the rear master lever (9). When activation of the rear master lever (9) is discontinued, the plunger (3) moves to the right-hand side of the figures due to the force of the first spring (13), until it reaches again the first axial position. The valve member (14) moves together with the plunger (3) in its closed position, but the valve member (14) is configured to contact with the pin (22) before the plunger (3), as it can be observed in Figure 4, so when the valve member contacts with the pin (22) the passage (16) opens, and the middle chamber (5) and the front chamber (4) are communicated again, so fluid flows to the front master port (1 1 ) and no longer to the front caliper port (12).

[0055] For applying more braking force on the front wheel, that is, in the caliper (24) when the valve member (14) is closed due to the activation of the rear master lever (9), the front master lever (8) should also be activated to brake both wheels. This would cause a pressure increase in the middle chamber (5), and in this situation the valve member (14) would receive two different pressures in opposite directions, namely: a pressure towards the right-hand side of the figures caused by the pressure at the front chamber (4), and a pressure towards the left-hand side of the figures caused by the pressure at the middle chamber (5).

[0056] Although the amount of pressure is the same in both chambers (4, 5), the valve member (14) would move to the left-hand side of the figures and it would open, because the section (14a) of the valve member (14) exposed to the middle chamber (5), is wider than section (14b) exposed to the front chamber (4), that is, as the area of the valve member (14) exposed to pressure at the middle chamber (5), is larger than the area of the valve member exposed to the pressure at the front chamber (4), the valve member (14) would move to the left (away from the pin (22)) opening the passage (16). In this way, the pressure exerted by the front master lever (8), is applied to the front caliper (24) through front and middle chambers (4, 5), thereby increasing the braking force.

[0057] Preferably, the valve sections (14a, 14b) of a part of them, are cylindrical, hence the diameter of the valve right section (14a) is larger than the diameter of the valve left section (14b), which means that the diameter of the fourth O-ring (21 ), the one closest to the rear chamber (6), is larger than the diameter of the third O-ring (20), the one closest to the front chamber (4).

[0058] The effect of having the fourth O-ring (21 ) with a larger diameter than the third O-ring (20), is that a force is generated on the valve member (14) towards the left-hand side of the figure, which ensures its opening during the pressure drop (to zero) in the front chamber (4).

[0059] As it can be observed, one of the main advantages of the invention, is that, in contrast to prior art CBS systems in which there is a physical limit to the stroke of the plunger to pressure on the front caliper, in the CBS system of the invention there is no limit to the pressure increase at the front caliper (24).

[0060] In prior art CBS systems, in order to increase braking force at front wheel by using a caliper with more volume or capacity, it is necessary to replace the entire CBS system by one of larger capacity, whereas in the present invention, to increase braking force at front wheel, it is only necessary to increase pressure with the front master lever (8) while holding down the rear master lever (9).

[0061] If it is desired to release pressure from the front caliper (24), the valve member (14) has to be open, so that pressure goes to the front master lever instead of to the front caliper. By reducing front master lever (8) pressure, pressure at the middle chamber (5) drops but not in front chamber (4), so the valve member (14) is still closed and pressure at the front caliper (24) cannot be lowered. It is necessary to generate force to the left-hand side of the figures on the valve member (14) to open it, and as the valve member (14) has more contact area at the right section (14b) than at its left section (14b), even if pressure is the same at the front and middle chambers (4, 5), the valve member (14) would moves to the left and would open, as described before.

[0062] The rear end of the plunger (3) is hermetically closed by a first plug (27), and the rear end of the housing (2) is hermetically closed by a second plug (28). The rear chamber (6) is formed in between first and second plugs (27, 28).

[0063] The operation of the CBS system of the invention and the advantages derived therefrom, are illustrated in Figures 6A to 11 B, and are as follows:

[0064] - When only the rear brake is activated: the CBS of the invention requires low force to start generating pressure in the front caliper and to reach the target pressure (mark 1 ), and CBS releases the front pressure late and fast (mark 2).

[0065] - When the front brake is activated and afterwards the rear one: the CBS of the invention does not increase front pressure when the front is maintained, and the rear is applied; and releases the front pressure once the front lever is not applied (mark 2).

[0066] - When the rear brake is activated first and afterwards the front one: the CBS of the invention increases front pressure while increasing front force.

[0067] - When rear while front: the CBS of the invention does not increase front pressure when the front is maintained, and the rear is applied (mark 1 ).

[0068] - When front while rear: the CBS of the invention releases the front pressure once the front lever is not applied (mark 2).

[0069] In the alternative embodiment of Figure 12, there is no rear caliper outlet port and instead, from the rear master level (9) fluid is sent to the CBS housing (2) through the rear master inlet port (7) and directly to the rear caliper (10) by means of a T-shaped connection (29). In this embodiment, the fluid only reaches the rear caliper (10) externally because there is no line connecting the CBS housing (2) to the rear caliper (10). The fluid that enters the rear chamber (6) would displace the plug (27) which would send fluid to the front caliper (24).

Claims

CLAIMS1 Combined Brake System (1 ) for vehicles, the system (1 ) comprising: an elongated housing (2) extending along an axis (X), a plunger (3) displaceable inside the housing (2) between two end positions, namely a first axial position and a second axial position, a front chamber (4) formed in the housing (2) at a first end (3a) of the plunger (3), a middle chamber (5) formed in the housing (2) at a middle zone of the plunger (3), a rear chamber (6) formed in the housing (2) at a second end (3b) of the plunger (3), wherein the rear chamber (6) is fluidly isolated from the front and middle chambers (4, 5), a rear master inlet port (7) fluidly communicated with the rear chamber (6) in the first and in the second axial positions of the plunger (3), a front master inlet port (1 1 ) communicated with the middle chamber (5), a front caliper outlet port (12) communicated with the front chamber (4), an internal passage (16) for communicating the middle chamber (5) with the front chamber (4), a first spring (13) placed in the front chamber (4) and pressing on the first end (3a) of the plunger (3), such that displacement of the plunger (3) from the first position towards the second position, is carried out against the force of the first spring (13), and displacement of the plunger (3) from the second position to the first position, is assisted by the first spring (13), a valve member (14) axially displaceable relative to the plunger (3), and configured for opening and closing the internal passage (16), wherein the system (1 ) is configured such that in the first axial position of the plunger (3), the valve member (14) is open, and the front master inlet port (11 ) and the front caliper outlet port (12) are fluidly communicated through the internal passage (16), and in the second axial position of the plunger (3), the valve member (14) is closed, and the front master inlet port (11 ) and the front caliper outlet port (12) are fluidly isolated.2.- Combined Brake System (1 ) according to claim 1 , further comprising a rear caliper outlet port (23) fluidly communicated with the rear chamber (6) in the first and in the second axialpositions of the plunger (3).3.- Combined Brake System (1 ) according to claim 1 or 2, wherein the valve member (14) is accommodated inside the plunger (3), and wherein a section of the internal passage is formed in between the valve member (14) and the plunger (3), such that, in its closed position the valve member (14) is in contact with the plunger (3) at said section, and in its open position, the valve member (14) is distanced from the plunger (3) at that section of the internal passage (16).4.- Combined Brake System (1 ) according to claim 3, wherein a section of the valve member (14a) closest to the middle chamber (5), is wider than a section (14b) of the valve member (14) closest to the front chamber (4).5.- Combined Brake System (1 ) according to claim 4, wherein the section (14a) is sealed with the plunger (3) by means of the third O-ring (20), and the section (14b) of the valve member (14) is sealed with the plunger (3) by means of a fourth O-ring (21 ), and wherein the diameter of the fourth O-ring (21 ) is larger than the diameter of the third O-ring (20).6.- Combined Brake System (1 ) according to any of the preceding claims, further comprising a second spring (15) placed inside the plunger (3) and in between the plunger (3) and the valve member (14), the second spring (15) pressing the valve member (14) towards the middle chamber (5).7.- Combined Brake System (1 ) according to claim 6, including an interstice (26) formed in between the valve member (14) and the plunger (3), and communicating the passage (16) with the cavity in which the second spring (15) is located.8.- Combined Brake System (1 ) according to any of the preceding claims, configured such that the volume of the rear chamber (6) increases and the volume of the front chamber (4) decreases, as the plunger (3) moves from the first position towards the second position.9.- Combined Brake System (1 ) according to any of the preceding claims, wherein a tubular chamber (17) is formed between the plunger (3) and the housing (2) at a middle section of the plunger (3), wherein this tubular chamber (17) is in fluid communication with the middle chamber (5), such that the front master inlet port (1 1 ) is communicated with the front caliper outlet port (12), through the tubular chamber (17), the middle chamber (5) and the internal passage (16), when the valve member (14) is open.10.- Combined Brake System (1 ) according to any of the preceding claims, wherein the rear master inlet port (7) and the rear caliper outlet port (23) are placed opposite each other. 11.- Combined Brake System (1) according to any of the preceding claims, comprising a pin(22) arranged orthogonally to the axis (X) and attached to the housing (2), wherein the pin (22) passes across the middle chamber (5) formed in plunger (3), such that the two end axial positions of the plunger (3), are defined by the contact of the plunger (3) with the pin (22).

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