BRAKE PEDAL SYSTEM WHICH SUPPLIES VARIABLE MECHANICAL ADVANTAGE Technical Field of the Invention

Current invention is related to a brake pedal system which by supplying variable mechanical advantage in accordance with the desired force value, provides the vehicle to stop in a limited distance even in the situations the vehicle is not supported by hydraulic system, in the process of brake pedal movement.

The invention is especially related to the brake pedal system, which provides variable mechanical advantage by utilizing multiple axes and intermediate arms, instead of transmitting force by making a single axis rotational motion.

Prior Art

Present systems appear as shown in Figure 3. In these systems the force affecting the pedal (1) is transferred to turning joint between mid-arm and piston of the master brake cylinders (5) as a higher force. The ratio between those two force values is defined as mechanical advantage. In the current systems during the braking, mechanical advantage is almost constant, it changes slightly. As long as the braking is hydraulically assisted, such a system operates satisfactorily. However, in the cases when there is no hydraulic pressure or the engine is not running, operator should press the pedal with much higher force since the force which should effect master brake cylinder increases or stopping distance of a vehicle increases with respect to the hydraulically assisted braking.

One of the developments related to the subject is about the reduced pedal travel braking system which is explained in the Europe patent the number of which is EP1946984B1. In this invention, as the main characteristic, at least, the length of the chamber connected to the secondary brake circuit was reduced. As feature, the system includes a location sensing mechanism which perceives the closure of subjected piston in the subjected chamber and sends a brake reference signal to the electronic stability control device's attention and by doing this it provides first conventional braking phase and a second conventional braking phase controlled by electronic stability control device.

Another invention in the current technique is a mechanical ABS powered brake described in TR 2005 030080, which can be used in all the vehicles which have hydraulic brake system and composes of a discharge nozzle, an upper body, a lower body, a double o-ring union , a single o- ring union, a T union, vibration valve and o-rings.

There is no similarity with the inventions mentioned above and the present invention, and accordingly the advantages of the present invention cannot be realized to these inventions mentioned.

To eliminate the disadvantages in the current technique, a multi-functional brake pedal system, which has various advantages over present systems, satisfies the technical requirements.

Short Description of the Invention

The present invention, inspired by the mentioned problems has been made to solve these problems.

The main goal of this invention is to eliminate the current technical disadvantages by producing a brake pedal system which will be used in brake systems to supply higher mechanical advantage ratio than the previous system. In this perspective the goal of the invention is, even in the situations there is no hydraulic support, obtaining a structure decreasing the necessary pedal force by creating a new brake pedal system with the use of high mechanical advantage in the situations which necessitates high force in the master brake cylinder during the last phase of the stroke. Also variable mechanical advantage brake system of the present invention increases the force applied to the master brake cylinders (8) with a lower force applied by the operator, thus reducing the operator's effort.

Another aim of the brake pedal system which is the subject of the invention is to provide a structure which prevents increasing of the stopping distance of the vehicle with respect to the hydraulically supported stopping distance, and it also provides a structure which reduces the dependency of the hydraulic support.

Another goal of the invention is to reduce' the time for pressing the brake and to get a more effective brake system. The structural and characteristic features and advantages of the invention can be better understood with the figures and related detailed explanation given below and therefore the assessment should be made considering those figures and detailed explanations. Figures Which Will be Helpful in Understanding of the Invention

Figure - 1a; Schematic view of the brake pedal system according to an embodiment of the present invention, as a first alternative and pedal (1) is not pressed. Figure - 1b; Side view, of the brake pedal system according to an embodiment of the present invention, as a first alternative and pedal (1) is pressed.

Figure - 2; Graph showing the mechanical advantage as a function of pedal (1) displacement of the prior system using a single lever and that of the present variable mechanical advantage system.

Figure - 3a; Schematic view of the previous pedal system at which the pedal (1) is not pressed. Figure - 3b; Schematic view of the previous pedal system at which the pedal (1) is pressed.

Figure - 4; Side view of the brake pedal system according to an embodiment of the present invention, second alternative construction.

Figure - 5; Side view of the brake pedal system according to an embodiment of the present invention, third alternative construction.

The figures are not to scale and some details which are not relevant to this invention might have been omitted. Same or similar elements performing same or similar function have the same number.

The Explanation of the Item References

1. Pedal 9. Intermediate arm

2. Pedal arm 10. Turning joint between crank and coupler

3. Fixed pivot of the Pedal Arm 11. Coupler

4. Prior art mid-arm (rigidly fixed with the 12. Turning joint between rocker and pedal arm) coupler 5. Turning joint between mid-arm and 13. Rocker

piston of the master brake cylinders 14. Crank

6. Balancing spring joint 15. Fixed pivot of the rocker

7. Balancing spring 16. Pin slot

8. Master brake cylinder

Detailed Description of the Invention

Invention is related to a system which includes pedal (1 ), pedal arm (2), fixed joint of the pedal arm (3), turning joint between mid-arm and piston of the master brake cylinder (5), balancing spring joint (6), balancing spring (7) and master brake cylinder (8).

The specialty of the invention, apart from brake pedal (1) providing variable mechanical advantage during the movement, is also to include;

- A pedal arm (2) and a crank (14) rotating about fixed pivot of the pedal arm (3),

-An intermediate arm (9) transmitting the rotation about a fixed pivot of the rocker (15); through a turning joint between mid-arm and piston of the master brake cylinders (5) to the master brake cylinder (8) ,

- A rocker (13) and an intermediate arm (9) integral to the rocker (13)

- A coupler (1 1) transmitting the rotation about the fixed pivot of the pedal arm (3) into rocker motion (13).

Preferred embodiments: The present invention will be described in detail by the preferred embodiment. It is explained just for the better understanding of the subject and in the formation that causing no limitation.

In Figure - 3a, a schematic drawing of the present state of art is shown when the pedal (1 ) is not pressed. The pedal arm (2) rotates about the pivot axis at the fixed pivot of the pedal arm (3). The prior art mid-arm (4) is rigidly connected to the pedal arm (2). Therefore pedal arm (2) and prior art mid-arm (4) make the same angle of rotation around the same axis. This prior art mid- arm is connected to the master brake cylinders (8) through turning joint between mid-arm and piston of the master brake cylinders (5) and to balancing spring (7) with balancing spring joint (6). In Figure - 3b a schematic drawing of the present state of art when pedal (1 ) is pressed is shown. Force exerted on the brake pedal (1) is amplified and transmitted to the master brake cylinders (8) through turning joint between mid-arm and piston of the master brake cylinders (5). This amplification ratio is the mechanical advantage. Although the mechanical advantage is a function of the pedal (1) position in such systems, it is almost constant within the range of pedal (1 ) motion. This is graphically shown in Figure - 2. Such a brake system does not cause any problem if it is hydraulically assisted. However, in case where there is no hydraulic pressure, as in the case when the engine is turned off the operator must press on pedal (1) with a higher force since the force required at the master brake cylinder (8) increases or the stopping distance will increase when compared with the hydraulically assisted case.

To prevent this situation double rotation axial system is used as it is seen in Figure- 1 a. Pedal arm (2), rotates around pedal arm stable joint (3) which attaches one tip of the crankshaft arm (14) to the place where it is located. Preferably mentioned crankshaft arm (14) and pedal arm (2) are integrated. Intermediate arm (9) rotates around fixed pivot of the rocker (15) with transmission of the motion coming from the crank (14) via coupler (1 1) to the rocker (13), and transmits motion with the help of turning joint between mid-arm and piston of the master brake cylinders (5). Mentioned fixed pivot of the rocker (15) fixes one tip of the rocker (13) to the place where it is located. Intermediate arm (9) which is rigidly connected to the rocker (13) also rotates about the fixed pivot of the rocker (15). So intermediate arm (9) and the rocker (13) rotates in the same direction and same amount of angle around fixed pivot of the rocker (15) (Figure -1 a and 1 b). Coupler (1 1) is attached to the pedal arm (2) with turning joint between crank and coupler (10) and to rocker (13) with the turning joint between coupler and rocker (12).

In Figure - 1 b side view of the brake pedal system as the first alternative is shown when the brake pedal (1) is pressed. When a rotation of the pedal arm (2) is imparted by pressing on pedal (1), this rotation is transmitted to the rocker (13) and intermediate arm (9) through coupler (1 1 ). Intermediate arm (9) is connected to the piston of the master brake cylinder (8) through turning joint between mid-arm and piston of the master brake cylinders (5) and the pedal arm (2) is attached to the balancing spring (7) via balancing spring joint (6). The force applied on the brake pedal (1) is amplified at the turning joint between mid-arm and piston of the master brake cylinder (5) and transmitted to the master brake cylinders (8). However in contrast to the present state of art, shown in Figure - 3a, the force amplification is not constant. With the appropriate dimensions of the crank (14), coupler (11) and rocker (13) mechanical advantage is increased towards the end of the pedal (1 ) motion and the force applied on to the master brake cylinder (8) is increased. An alternative construction is shown in Figure - 4. In the previous alterative motion transmission element was coupler (1 1), but in this alternative rotation of the pedal arm (2) is transmitted to the rocker (13) through a pin (1 1 ) moving in a pin slot (16) on rocker (13). With the help of the brake pedal's (2) movement in pin slot(16) and provides the rocker (13) to make the desired motion. There are also a balancing spring (7) and a balancing spring joint (6) in this alternative.

Another alternative construction of the present invention is shown in Figure - 5. The mechanism used in this formation is a cam mechanism. According to this, rocker (13) is made as an arm. In this case motion transmission element is a cam. Cam has a curve profile as shown in Figure. By this way the rocker (13) is made to do the desired motion during brake arm's (2) movement. A balancing spring (7) is attached at balancing spring joint (6) to

the pedal arm (2) as in the current system.

The increase of the mentioned force is given in Figure- 2 which shows the change of mechanical advantage during the brake pedal course in the old technique and in the system which is subject to this invention. In this drawing, average mechanical advantage ratio is given in dashed lines. Slightly inclined line is the mechanical advantage curve for a single lever system. This straight and small angle inclined line shows that single lever (old technique) provides low mechanical advantage. On the other hand, the mechanical advantage the invention provides is shown as a function and the increasing line shows uniform increase in the ratio of mechanical advantage.

As the pedal (1 ) is displaced, at the start the mechanical advantage is low since the force required at the master brake cylinder (8) is low; towards the end of the stroke, the mechanical advantage increases, thus applying a high force on the master brake cylinder (8) for the same pedal force is necessary. Hence even when there is no hydraulic assistance, either the force required to stop the vehicle is reduced or the stopping distance is reduced with the same pedal force.