DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
AND
The Patents Rules, 2003

COMPLETE SPECIFICATION
(Section 10 and Rule 13)

TITLE
A CONTROL SYSTEM FOR STEERING AND BRAKING OF A VEHICLES WITH PROPORTIONALLY CONTROLLED SAHR CLUTCHES

APPLICANT
(a) BEML LTD.
(b) An Indian Company,
(c) BEML Soudha,
No 23/1, IV Main, Sampangiramanagar,
Bengaluru, Karnataka, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF THE INVENTION
This invention relates to a control system for steering and braking of a vehicle. Particularly this invention relates to a control system for steering and braking of a vehicle for use in off-highway Crawler Dozers.
STATE OF THE ART IN THE FIELD
Crawler dozers are continuous tracked machines fitted with front-mounted blades to move or push large quantities of material such as soil, sand and rubble. In crawler type equipments, conventional steering systems are commonly manual lever operated steering system in which the steering of the equipment is controlled through the use of pair of clutch-brake mechanisms located in the driveline of each side of the track.
An example of a control system for steering and braking of a vehicle is shown in Figure 1. In Figure. 1, an engine (1) is connected to a PTO Unit (2). The PTO unit (2) is connected to a oil delivery unit (3). The oil delivering unit (3) is connected to clutches through a control valve and mechanical lever for right side and left side steering. A control valve and mechanical lever for left side steering is connected to a intermediate shaft (9L). The intermediate shaft (9L) is connected to atleast two double reduction gears (12L) and (13L). The double reduction gears (12L) are connected to a final left output shaft and left drive sprockets (14L and 15L respectively) which in turn will drive the Track Chain.
There are disadvantages associated with the conventional steering and brake control system. One if the disadvantage is that precise turning radius and direction of turning are not only dependent upon steering lever actuation but also on the other functional items in the control system.
Another disadvantage associated with the conventional steering and brake control system is that the function of mechanical steering system is based on activation of mechanical levers and further sliding motion of steering and brake valve spools and springs inside the control valve body.
Yet another disadvantage associated with the conventional steering and brake control system is that the system provides ‘jerk’ also known as ‘shift shock’.
Still another disadvantage associated with the conventional steering and brake control system is that the system is manually operated.
A further disadvantage associated with the conventional steering and brake control system is that the issues of steering/Brake spool stickiness and jamming issue are reported.
Another disadvantage associated with the conventional steering and brake control system is that response of mechanical lever type or spool type control valves is slow.
Yet another disadvantage associated with the conventional steering and brake control system is that maintenance cost is high.
OBJECTS OF THE INVENTION
Therefore, an object of the present invention is to provide a control system for steering and braking of a vehicle which obviate the disadvantages associated with the prior art system.
Another object of the present invention is to provide a control system for steering and braking of a vehicle which provides a control system for proportional steering and brake for use in off-highway Crawler Dozers.
Yet another object of the present invention is to provide a control system for steering and braking of a vehicle which minimizes the ‘jerk’ also known as ‘shift shock’.
Still another object of the present invention is to provide a control system for steering and braking of a vehicle which provides a control system for both Electronic vehicle (ENGINE & TRANSMISSION is an electronic) and Mechanical Vehicle (Non electronic ENGINE & TRANSMISSION).
A further object of the present invention is to provide a control system for steering and braking of a vehicle which uses valves to resolve steering/Brake spool stickiness and jamming issue.
Another object of the present invention is to provide a control system for steering and braking of a vehicle which provides quick response as compared to mechanical lever type or spool type control valves.
Yet another object of the present invention is to provide a control system for steering and braking of a vehicle which has low maintenance cost.
SUMMARY OF THE INVENTION
According to this invention, a control system for steering and braking of a vehicles comprising a PTO (power take-off) adapted to be connected with an engine such that to transfer engine torque to a torque converter connected to a clutch being connected gear box. The gear box being connected with a shaft connected to the bevel gear set being connected to an input shaft. The input shaft being connected with shafts being connected to left output shaft through respective spring actuated and hydraulic release (SAHR) left brake and clutch and right output shaft through respective SAHR right brake and right clutch. The output shafts being connected to respective reduction gears and also to respective final drives being connected to respective input shafts adapted to secured with wheels of the vehicles. Characterized a palm control lever being provided to steer and apply brake as and when required. An electronic controller being provided to receive signals from the palm controller and control valves for left and right steering clutches and valves for left and right brake. A normally closed quick fill valves being provided to fill the steering clutches faster through proportional pressure control valves provided for disengaging the spring-actuated steering clutches to turn the equipment in the left or right direction. Normally closed quick dump valves being provided to drain the steering clutch immediately when the palm controller being brought back to its neutral position and to drain the brake clutch during engaging of brake clutch by spring for sharp turning of the equipment, a battery being provided to energize the palm control lever and the controller.
BRIEF DESCRIPTION OF THE DRAWINGS
A control system for steering and braking of a vehicle according to a preferred embodiment of this invention is herein described and illustrated in the accompanying drawings, wherein;
Figure – 1, Illustrates conventional steering and brake control mechanism.
Figure – 2, illustrates a schematic representation of the first embodiment of the control system for steering and braking.
Figure – 3, illustrates a Control Logic / algorithm for combined steering / brake pressure response characteristics.
DETAILED DESCRIPTION OF THE INVENTION
A control system for steering and braking of a vehicle according to the present invention comprises a final drive assembly in which steering clutches are kept engaged by spring force, a cartridge type proportionally controlled steering and brake valve (PCSBV) connected to a final drive clutch assembly via pressure line, an electronic steering controller circuit including joystick and controller. The PCSBV assembly includes two proportional, one valve in association with the fill valve and a dump valve for steering clutch operation and another proportional valve for brake booster operation.
Referring to the drawings, particularly figure 2, a control system known in the art is shown. The conventional system comprises A control system for steering and braking of a vehicles comprising a PTO (power take-off) (2) adapted to be connected with an engine (1) such that to transfer engine torque to a torque converter (4) connected to a clutch (5) being connected gear box (6). The gear box (6) being connected with a shaft (7) connected to the bevel gear set (8) being connected to an input shaft (9). The input shaft (9) being connected with shafts (10) and shaft (11). Shaft (11) being connected to output shaft (12L) through respective spring actuated and hydraulic release (SAHR) brake (13L) and clutch (14L) and (12R) through respective SAHR brake (13R) and clutch (14R). The output shafts (12L and 12R) being connected to respective reduction gears (15L, 15R, 16L and 16R) and also to respective final drives (17L & 17R) being connected to respective input shafts (18R and 18L) adapted to secured with wheels of the vehicles. Characterized a palm control lever (25) being provided to steer and apply brake as and when required. An electronic controller (23) being provided to receive signals from the palm controller and control valves (19LSPV and 19RSPV) for left and right steering clutches and valves (22LBPV and 22RBPV) for left and right brake. A normally closed quick fill valves (21LQF and 21RQF) being provided to fill the steering clutches faster through proportional pressure control valves (19LSPV, 19RSPV) provided for disengaging the spring actuated steering clutches (14LSC & 14RSC) to turn the equipment in the left or right direction. Normally closed quick dump valves (20LD and 20RD) being provided to drain the steering clutch immediately when the palm controller (25) being brought back to its neutral position and to drain the brake clutch during engaging of brake clutch by spring for sharp turning of the equipment. A battery being provided to energize the palm control lever and the controller.
Figure 3 illustrates a relationship between the stroke or percentage (%) of a joystick movement and the hydraulic pressure of the proportional control valves for a vehicle. The four proportional valves are arranged in such a way that it exhibits the stroke Vs hydraulic pressure characteristic that the timing of the rise of hydraulic pressure of the proportional control valve 19LSPV & 19RSPV for steering clutches is earlier than the falling of pressure of the proportional control valves 22LBPV & 22RBPV for brake clutches to disengage as shown by the curves in Figure.5.
In one embodiment, the control system is used for handling higher capacity flow in excess of 300 Liters Per Minute (LPM) in a compact design of cartridge type proportional control valve and to avoid higher pressure drop which is more than the operating pressure of steering system fill valve that is incorporated with proportional steering valve to fill the clutch at faster rate and at higher flow to avoid delay in dis-engagement of the steering clutch and further delay in steering of the equipment. Similarly, dump valve is incorporated with proportional steering valve for quick release of steering clutch when dump valve is turned back to its normal operation by clutch engagement to avoid drag of the equipment in undesired direction and also to avoid shift shocking or jerk due to delay in engagement. The proportional brake valve is configured to facilitate activation of the brake by the activation of the brake clutch to achieve smooth function of sharp steering operation.
Certain features of the invention have been described with reference to the exemplary embodiments. However, the description is not intended to be construed in a limiting sense. Various modifications of the exemplary embodiments as well as other embodiments of the invention, which are apparent to the persons skilled in the art to which the invention pertains, are deemed to lie within the spirit and scope of the invention.
,CLAIMS:We Claim:
1. A control system for steering and braking of a vehicles comprising a PTO (power take-off) (2) adapted to be connected with an engine (1) such that to transfer engine torque to a torque converter (4) connected to a clutch (5) being connected gear box (6), the gear box (6) being connected with a shaft (7) connected to the bevel gear set (8) being connected to an input shaft (9), the input shaft (9) being connected with shafts (10) and shaft (11), shaft (11) being connected to output shaft (12L) through respective spring actuated and hydraulic release (SAHR) brake (13L) and clutch (14L) and (12R) through respective SAHR brake (13R) and clutch (14R), the output shafts (12L and 12R) being connected to respective reduction gears (15L, 15R, 16L and 16R) and also to respective final drives (17L & 17R) being connected to respective input shafts (18R and 18L) adapted to secured with wheels of the vehicles, characterized a palm control lever (25) being provided to steer and apply brake as and when required, an electronic controller (23) being provided to receive signals from the palm controller and control valves (19LSPV and 19RSPV) for left and right steering clutches and valves (22LBPV and 22RBPV) for left and right brake, a normally closed quick fill valves (21LQF and 21RQF) being provided to fill the steering clutches faster through proportional pressure control valves (19LSPV, 19RSPV) provided for disengaging the spring actuated steering clutches (14LSC & 14RSC) to turn the equipment in the left or right direction, normally closed quick dump valves (20LD and 20RD) being provided to drain the steering clutch immediately when the palm controller (25) being brought back to its neutral position and to drain the brake clutch during engaging of brake clutch by spring for sharp turning of the equipment, a battery being provided to energize the palm control lever and the controller.
2. The control system for steering and braking of a vehicles as claimed in claim 1, wherein the oil delivery unit comprises hydraulic pump.
3. The control system for steering and braking of a vehicles as claimed in claim 1, wherein the oil delivery unit is connected with the PTO so as supply oil the PTO, to torque converter unit, forward clutch and to speed change gear box.
4. The control system for steering and braking of a vehicles as claimed in claim 1, wherein the single palm control lever comprises a joystick.
5. The control system for steering and braking of a vehicles as claimed in claim 1, wherein valves comprises cartridge type proportional valves such that to receive electrical signal from the controller and function proportionally to regulate oil flow and maintain required pressure of the steering clutches and brake cylinders.
6. The control system for steering and braking of a vehicles as claimed in claim 1, wherein the controller comprises a control logic adapted to act based on the signals received from the joystick.
7. The control system for steering and braking of a vehicles as claimed in claim 1, wherein SAHR steering and Brake clutches will engage and/or disengage the clutches based on signal from said proportional valves (19LSPV & 19RSPV) and brake clutches will engage or dis-engage according to the signal from said proportional valves (22LBPV & 22RBPV).
Dated this 12th day of March, 2020

R. P. Yadav
IN/PA - 954
of sr4ipr Partners
Applicant’s Attorney