Title of invention:

Improved Braking system in open loop hydraulic driven vehicle.

Field of Invention;

The present invention is related to Improved Braking system in open loop hydraulic driven vehicle and more particularly it relates to Braking system in open loop hydraulic driven vehicle.

Background of Invention:

The existing hydraulic braking mechanisms in the open loop hydraulic driven vehicles / machinery are

Using double over center valve to avoid over running of the vehicle/ system.

No hydraulic assistance provided for braking from the main source of hydraulic power and the same is not linked to the break pedal.

Free wheeling of the vehicle and over running control of the vehicle together is not provided

Draw backs of the existing state of art:

Since double over centre vale or special "mudroc" valves are provided to stop the over running of the vehicle, normal free wheeling of the vehicle similar to that of other mechanical driven vehicle is not possible.

In Dual over center valve designs, there is no means of by passing the over center valve which leads to efficiency loss.

In the existing state hydraulic open loop driven vehicle no hydraulic assistance [Hydrostatic] braking is provided which is linked to the brake pedal from the main source of hydraulic power.

In the existing state hydraulic open loop driven vehicle all of these three features together [free wheeling, hydraulic braking by activating the brake pedal and a mechanism to stop the over running of the vehicle] are not possible.
Objects of the invention:

The main objective of the invention is to eliminate some of the disadvantageous of the existing hydraulic open loop driven vehicles and machines.

Another object of the present invention is to provide an improved breaking system with added advantageous.

Yet another object of the present invention is to provide an improved safety while driving hydraulic open loop driven vehicle with improved comfort for driving.

Yet another object of the present invention is to increase the efficiency (by introducing over-center valve bypass option).

Summary of invention;

An improved braking system in open loop hydraulic driven vehicle comprising at least one over centre valve adapted to be mounted on the return line configured for controlling the hydraulic flow for braking system; at least one hydraulic pump [1] for pumping the hydraulic fluid in the system for developing hydraulic pressure in the system; at least one valve [2] configured to route the hydraulic fluid to other predetermined valves when activated; at least one poppet valve [6] configured for allowing and restricting the flow of hydraulic fluid by its opening and closing; plurality of check valves for controlling the flow of hydraulic fluid in the system at various points; at least one direction control valve [4]; at least one brake pedal; at least one Hydraulic motor [5] configured for being operated by the flow of the hydraulic fluid through the system and for acting as braking device for the system; at least one pilot line sensor [12] configured to sense over running of the vehicle and; at least one storage tank (11) for storing hydraulic fluid.

The braking is effected by activating break pedal adapted to generate back pressure to the motor by diverting the flow of hydraulic fluid from in put side to the output side of the motor i.e. from valve (2) through check valve (7) and poppet valve (6) to reach motor return output line through direction control valve (4) to create back pressure in the motor return output line before over center valve (8) to exert braking to the motor and/or to assist other brakes of the total system.

The poppet valve (6) is in closed condition when it is energized and blocks the oil flow through it and forces the oil to pass through the single over centre valve (8) to the tank (11) and when it is de-energised it is in open condition and allows the oil to flow through it to tank (11).

The poppet valve (6) is energized in sloppy/hilly conditions to offer resistance during overrunning of the vehicle. The pilot line sensor [12] is inbuilt in the over centre valve configured to sense over running of the vehicle.

The normal mode the hydraulic fluid passes through the valve (2) and operates the motor. The motor return output line is pressurized to an extent to exceed back pressure setting value of the over center valve (8) resulting in the opening of the over center valve (8).

The inbuilt sensor (12) of the single over centre valve (8) senses pressure drop just after the check valve (3) for processing through set program on predetermined pressure values by which the opening and closing of the single over centre valve (8) is controlled.

The pressure drop after the check valve (3) sensed by inbuilt sensor (12) closes the single over centre valve (8) to increase the back pressure in the motor's return line by offering resistance for free movement of the motor, resulting braking action. By bypassing said over centre valve [8] improves the efficiency of the system.

If the poppet [6] is not energized in case of overrunning of the vehicle then the break pedal [10] is operated and the hydraulic fluid will be redirected to the return line of the motor [5] and the resistance / brake will be applied giving priority to said breaking system. The poppet valve can be de-energised while the vehicle runs on plains and not so sloppy or hilly area.

The pressure drop is resulted due to cavitation developed after the check valve (3) in the pipe line of hydraulic system when the actual speed of the vehicle is higher than the hydraulic pump output during running down the slope of the vehicle closes the single over centre valve (8) to increase the back pressure in the motor's return line by offering resistance for free movement of the motor, resulting braking action..

When the vehicle is in its normal mode or climbing the slope the pilot line (12) senses the pressure within the acceptable limits then the single over centre valve (8) is always kept in open condition.

The efficiency of the system is also increased by deactivating / de-energising the poppet valve to open it fully so that the hydraulic fluid will directly flow to the tank by bypassing the single over centre valve (8) and as even fully open single over centre valve (8) offers small [little] resistance to flow of hydraulic fluid resisting the free movement of the motor and decreasing the efficiency of the system.

Statement of invention:

Accordingly the present invention provides an improved braking system in open loop hydraulic driven vehicle comprising at least one over centre valve adapted to be mounted on the return line configured for controlling the hydraulic flow for braking system;

at least one hydraulic pump [1] for pumping the hydraulic fluid in the system for developing hydraulic pressure in the system;

at least one valve [2] configured to route the hydraulic fluid to other predetermined valves when activated;

at least one poppet valve [6] configured for allowing and restricting the flow of hydraulic fluid by its opening and closing;

plurality of check valves for controlling the flow of hydraulic fluid in the system at various points;

at least one direction control valve [4];

at least one brake pedal;

at least one Hydraulic motor [5] configured for being operated by the flow of the hydraulic fluid through the system and for acting as braking device for the system;

at least one pilot line sensor [12] configured to sense over running of the vehicle and;

at least one storage tank (11) for storing hydraulic fluid.

Brief description of Drawings:

According to the present invention,
Figure 1 shows Normal operation with over centre bypass.
Figure 2 shows Braking mode of the improved braking system.
Figure 3 shows over running protection mode.

Brief description of invention:

The present invention consists of a hydraulic system which automatically sense the down hill mode of a open loop drive vehicle and applies pre settable resistance by diverting the flow from in put side to the output side of the motor and also while in a normal driving mode while the brake pedal is applied the same resistance is triggered in assisting the other independent brakes. It is an arrangement which makes the braking of an open loop hydraulic driven vehicle more effective and provides protection against over running of the vehicle in slopes and hilly area driving. During the vehicle driven, while applying brake a hydraulic assistance is provided by way of pressuring the tank line / return line of the hydraulic motor. While the tank line is pressurized the hydraulic motor exerts resistance to the open loop hydraulic driven vehicle which assists the other mechanical brakes in the vehicle. The invention also consists of selectable option of the same with priority system for braking pedal.

Present invention consists of a single over centre valve mounted on the tank line with a by passing selectable option with over riding / priority function for breaking pedal. This enables to have free wheeling during the normal mode and he braking is effected by break pedal diverting the flow back to tank line before over center valve which is set to create backpressure to the motor while the break pedal is activated. It also avoids overrunning of the vehicle in slopes. Present system incorporates the selectable bypassing arrangement with overriding provision for braking which improves the efficiency of the system. More effective braking is possible during driving which is linked to the break pedal.

All the three features possible together are as follows:
i. free wheeling.
ii. hydraulic braking by activating the break pedal.
iii. a mechanism to stop the over running of the vehicle.

Detailed description:
The present invention consists of following arrangements which enables open loop hydraulic drive vehicle to be driven with improved efficiency and braking system avoiding overrunning of he vehicle in the sloppy areas with an option of bypass to the over running of the vehicle with priority breaking option.

The hydraulic diagram of Figure - 1 represents present invention in the normal running mode which consists of hydraulic pump [1] and valve [2], check valve [3]. Direction control valve [4], Hydraulic motor [5] and the valve (2) connected and operated by a foot break pedal [10].While in the normal mode the oil passes through the valve (2) and operates the motor.

Referring figure-2 which shows braking mode of the improved braking system, when the break pedal [10] is operated the flow is diverted from valve (2) through check valve (7) and poppet valve (6) simultaneously to reach motor return/output line and the return line of the motor is pressurized to an extent to exceed back pressure setting value of the over centre valve [8] to create backpressure to the motor return line. The pressure exerts resistance to the motor and applies brake and or assists other brakes of the total system.

The poppet valve (6) is in closed condition when it is energized and blocks the oil flow through it and forces the oil to pass through the single over centre valve (8) to the tank (11) and when it is de-energised it is in open condition and allows the oil to flow through it to tank (11).

When the brake pedal is in pressed it activates the valve (2) to route the oil from valve (2) to check valve (7) irrespective of poppet valve (6) be open or not. If poppet valve (6) is in open condition then the oil from valve (2) will be pressurized through poppet valve (6) & check valve (7) to offer back pressure to the output line of motor through direction control valve (4) such that it will result in the opening of the single over centre valve (8). As the oil is diverted from valve (2) directly to poppet valve (6) and check valve (7), results in pressure drop in the line after the check valve (3). This pressure drop is sensed by the inbuilt sensor of the single over centre valve (8). The opening and closing of the single over centre valve (8) is controlled by set program which uses these pressure values of the fluid sensed in the loop sensed just after the check valve (3) for processing. The pressure drop sensed after the check valve (3) closes the single over centre valve (8) to increase the back pressure in the motor's return line by offering resistance for free movement of the motor, resulting braking action.

Even if the poppet [6] is not energized in case of overrunning of the vehicle and if the break pedal [10] is operated the oil will be redirected to the return line of the motor [5] and the resistance / brake will be applied. In any given point of time the breaking system gets the priority. By bypassing the over centre valve [8] the efficiency of the system is improved.

Now referring to figure -3. During the normal running condition, when the poppet valve [6] is energized by an hydraulic operated or an electrically operated circuit, it blocks the free flow of oil in the return path and makes the oil to pass through the over centre valve [8] which can sense the over running of the vehicle through the pilot signal [12] and will apply resistance [ brake] to the motor's return line. The poppet [6] can be energized in sloppy/ hilly conditions and the resistance for overrunning will be always on.

While the vehicle is running down the slope the actual speed of the vehicle is higher than the hydraulic pump output. The speed of the hydraulic pump is related to the engine rpms which is operated by the foot accelerator. If the vehicle is running at higher speed than the intended or desired speed then there will be cavitation developed in the oil pipe line after the check valve (3). This pressure drop will be sensed by the inbuilt sensor of the single over centre valve (8). The opening and closing of the single over centre valve (8) is controlled by set program which uses these pressure values of the fluid sensed in the loop sensed just after the check valve (3) for processing. The pressure drop closes the single over centre valve (8) to increase the back pressure in the motor's return line by offering resistance for free movement of the motor, resulting braking action.

When the vehicle is in its normal mode or climbing the slope, the pilot line (12) is the connection of an inbuilt sensor in the single over centre valve located after the check valve (3) which senses the pressure in the oil pipeline. If the pressure sensed is found to be within the acceptable limits then the single over centre valve (8) is always kept in open condition.

The poppet valve also can be de-energised while the vehicle runs on plains and not so sloppy or hilly area which makes the system to run in figure 1 condition to take advantage of the following situation

Since the oil is routed through the single over centre valve (8) in when the pressure sensed is found to be within the acceptable limits i.e. in normal conditions even when the single over centre valve (8) is in fully open condition still it offers small [little] resistance to oil flow due to which there is slight pressure increase which will in return offer resistance to the free movement of the motor thereby decreasing the efficiency of the system. In this case the poppet valve can be deactivated / de-energised to open it fully so that the oil will directly flow to return in the tank by bypassing the single over centre valve (8) which will make the system to run in figure 1 mode.

When the break pedal is pressed irrespective of whether the system operates in Figure 1 or Figure 3 mode the system will switch to figure 2 configuration mode there by allowing braking system to get the priority.

Novel features of the invention:

Novel feature of the invention are,

Using the hydraulic oil from the pump out put to assist the breaking system by diverting the oil through a single over-centre valve mounted on the tank line with bypassing a selectable option with over riding / priority function for breaking pedal which is connected to the valve. i.e. when brake pedal is operated it gets priority over all other available options.

Using a single over-centre valve to assist the brake.

Bypassing a selectable option with over riding / priority function for breaking pedal.

A breaking pedal connected to a valve (2) with priority option.

Providing selectable option for avoiding over running of the vehicle in sloppy / hilly areas.

Advantageous over all other known alternatives:

Eliminates some of the major disadvantageous of a hydraulic open loop system driven drives and vehicles.

Automatic over running protection using a single over centre valve.

Better braking efficiency as hydraulic oil from the pump is used to apply resistance to the motor.

Overrunning protection optionally provided with breaking system given priority in all circumstances.

Enables an open loop driven vehicle, to be driven similar to other mechanically driven vehicles with varying engine rpms operated by accelerator pedal.

Selectable option provides better efficiency by introducing over-center valve bypass option.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We claim:
1. An improved braking system in open loop hydraulic driven vehicle comprising

at least one over centre valve adapted to be mounted on the return line configured for controlling the hydraulic flow for braking system;

at least one hydraulic pump [1] for pumping the hydraulic fluid in the system for developing hydraulic pressure in the system;

at least one valve [2] configured to route the hydraulic fluid to other predetermined valves when activated;

at least one poppet valve [6] configured for allowing and restricting the flow of hydraulic fluid by its opening and closing;

plurality of check valves for controlling the flow of hydraulic fluid in the system at various points;

at least one direction control valve [4];

at least one brake pedal;

at least one Hydraulic motor [5] configured for being operated by the flow of the hydraulic fluid through the system and for acting as braking device for the system;

at least one pilot line sensor [12] configured to sense over running of the vehicle and;

at least one storage tank (11) for storing hydraulic fluid.

2. The braking system as claimed in claim 1 wherein said braking is effected by activating break pedal adapted to generate back pressure to the motor by diverting the flow of hydraulic fluid from in put side to the output side of the motor i.e. from valve (2) through check valve (7) and poppet valve (6) to reach motor return output line through direction control valve (4) to create back pressure in the motor return output line before over center valve (8) to exert braking to the motor and/or to assist other brakes of the total system.

3. The braking system as claimed in claim 1 wherein said poppet valve (6) is in closed condition when it is energized and blocks the oil flow through it and forces the oil to pass through the single over centre valve (8) to the tank (11) and when it is de-energised it is in open condition and allows the oil to flow through it to tank (11).

4. The braking system as claimed in claim 1 wherein said poppet valve (6) is energized in sloppy/hilly conditions to offer resistance during overrunning of the vehicle.

5. The braking system as claimed in claim 1 wherein said pilot line sensor [12] is inbuilt in the over centre valve configured to sense over running of the vehicle.

6. The braking system as claimed in claim 1 wherein in the normal mode the hydraulic fluid/oil passes through the valve (2) and operates the motor.

7. The braking system as claimed in claim 2 wherein said motor return output line is pressurized to an extent to exceed back pressure setting value of the over center valve (8) resulting in the opening of the over center valve (8).

8. The braking system as claimed in claim 1 wherein said inbuilt sensor (12) of the single over centre valve (8) senses pressure drop just after the check valve (3) for processing through set program on predetermined pressure values by which the opening and closing of the single over centre valve (8) is controlled.

9. The braking system as claimed in claim 1 wherein said pressure drop after the check valve (3) sensed by inbuilt sensor (12) closes the single over centre valve (8) to increase the back pressure in the motor's return line by offering resistance for free movement of the motor, resulting braking action.

10. The braking system as claimed in claim 1 wherein if said poppet [6] is not energized in case of overrunning of the vehicle then the break pedal [10] is operated and the hydraulic fluid will be redirected to the return line of the motor [5] and the resistance / brake will be applied giving priority to said breaking system.

11. The braking system as claimed in claim 1 wherein said poppet valve can be de-energised while the vehicle runs on plains and not so sloppy or hilly area.

12. The braking system as claimed in claim 1 wherein bypassing said over centre valve [8] improves the efficiency of the system.

13. The braking system as claimed in claim 1 wherein pressure drop is resulted due to cavitation developed after the check valve (3) in the pipe line of hydraulic system when the actual speed of the vehicle is higher than the hydraulic pump output during running down the slope of the vehicle closes the single over centre valve (8) to increase the back pressure in the motor's return line by offering resistance for free movement of the motor, resulting braking action..

14. The braking system as claimed in claim 1 wherein when the vehicle is in its normal mode or climbing the slope the pilot line (12) senses the pressure within the acceptable limits then the single over centre valve (8) is always kept in open condition.

15.The braking system as claimed in claim 1 wherein the efficiency of the system is also increased by deactivating / de-energising the poppet valve to open it fully so that the hydraulic fluid will directly flow to the tank by bypassing the single over centre valve (8) and as even fully open single over centre valve (8) offers small [little] resistance to flow of hydraulic fluid resisting the free movement of the motor and decreasing the efficiency of the system.

16. The improved braking system in open loop hydraulic driven vehicle substantially as herein described in description as illustrated with reference to accompanying drawings.