|Title of Invention||
A METHOD AND SYSTEM FOR TAKING SHARP U-TURNS BY FOUR WHEEL VEHICLES
|Abstract||In this invention a method and associated system for reducing the turning radius and assist the vehicle to take U-turns in a lesser road space is described. The method is based on the fact that while taking a sharp turn in a direction if the rear inner wheel is locked then the vehicle will take lesser space with centre of rotation nearly at the locked wheel. The proposed system consists of introducing a number of shut-off valves, limit switches and other devices to enable automatic locking of a particular rear wheel. This invention is essentially useful for four wheeled vehicles with front wheel drive. It also can be used for vehicles with rear wheel drive provided the design of differential and transmission takes the extra loads generated during turning with a rear wheel fully or|
|Full Text||A METHOD AND SYSTEM FOR TAKING SHARP U-TURNS BY FOUR
Field of application
The invention relates to four wheeled automobiles with front wheel drive. The turning radius is reduced by employing this invention. Lesser space is required for U-turns, when turned at slow speeds. This can be used for vehicles with rear wheel drive also in some cases.
The turning radius of a four wheeler depends on the steering linkage design. More is the maximum turn, 0i, of the front wheel (see Fig.l) lesser is the turning radius. 0i is fixed for a given vehicle. For a given vehicle there is no other method in use by which turning radius is decreased.
A method is proposed in this invention where in the turning radius can be decreased for a given steering linkage design of a vehicle.
Brief description of drawings
Fig.l shows position of front wheels at maximum turning position.
Fig.2a & Fig.2b shows the wheel to be locked while taking sharp turns.
Fig.3 shows reconfigured independent hand-brake levers located besides driver seat.
Fig.4 shows location of shut-off valves and limit switches.
Fig.5 shows arrangement of limit switch on front axle housing.
Fig.6 shows an arrangement for automatic braking.
Fig.7 shows another arrangement for automatic braking.
By locking the inner rear wheel (1) [see Fig. 2a and 2b] after the steering wheel is turned fully, the vehicle will take a shorter turning space when turned slowly. This happens because of the fact that the Wheel (1) remains at nearly one location (except for small amount of skidding) and contact point of wheel (1) is the point about which the vehicle will tend to rotate. In a moderate to highly loaded vehicle the friction force on the inner rear wheel (1) under locked condition will be enough to keep it at one location w.r.t road. In a lightly loaded vehicle there can be small slipping of the locked wheel (l).The locking of a particular rear wheel (after the steering wheel is fully rotated) can be done by either of the following two methods.
1. Manual Method
If the hand brake is designed to lock rear wheels only, then this method can be adopted. The hand brake (see Fig.3) is redesigned so that it is split into two hand operated levers which independently actuates brake shoes of the rear wheels. When it is required to turn the vehicle to right side at low speeds e.g. taking a U-turn towards right side, the right hand-brake (2) alone can be pulled up so that only rear right wheel is locked, and vehicle takes U- turn in a lesser road space. The right hand-brake lever (2) shall be pulled only after turning the steering wheel fully in the clockwise direction. Similarly, when it is required to take a U-turn or sharp turn towards left side slowly then the left hand brake lever (3) shall be pulled up after the steering wheel is completely rotated in the anti clock wise direction. For normal hand-brake application when the vehicle is stationery, the split knobs (4) and (5) which are together shall be pulled up.
2. Automatic method
Four numbers of electrically operated shut-off valves (6), (7), (8) and (9) of suitable kind that are normally open are placed in the brake-fluid lines of each of the four wheels (see Fig.4).Whenever the steering is rotated to the extreme position in the clockwise direction, a limit switch (11) which is fixed on the right side of the front axle is operated by right front wheel (13) as shown in Fig.5 and upon receiving electrical signal from the limit switch (11) a signal is given by a suitable computer or microprocessor or microcontroller to close all shut-off valves other than the valve (9) which is fitted on the brake-fluid line leading to the brake-actuator of the right rear wheel (15). Immediately after closure of above mentioned valves, an auto braking system (10) is actuated, thus pressurising the brake fluid line. By this action the rear right wheel alone is locked.
Similarly, when the steering wheel is rotated to extreme anti clock wise direction a limit switch (12) is actuated by the front left wheel (14) and a signal is given by microprocessor or microcontroller to close all valves other than (8). Immediately after closure of above mentioned valves, the auto braking system (10) is actuated, thus pressurising the brake fluid line, causing the rear left wheel alone to be locked.
The arrangement of limit switch is shown in Fig. 5. When the wheel (13) rotates to extreme position in the direction shown in Fig. 5 a limit switch (11) is activated. The limit switch (11) is placed on a leaf spring (19) which is fixed on a base (18). (18) is fixed suitably on the front axle housing (17). Similar arrangement, which is a mirror image of this arrangement about mid longitudinal plane of vehicle, is made for left limit switch (12). The auto braking system is shown in Fig.6 and Fig.7. Auto braking system (10) consists of pressurising the brake fluid line at any suitable location before the location of the shut off valves (6), (7), (8) and (9). Three methods of auto braking are proposed below.
Method-1 (see Fig.6)
A cylinder (20), with a piston (21) in it, is connected to brake-fluid line. The piston (21) is kept pressed on to stoppers (22) attached to cylinder (20) by means of a compressed spring (23). The piston is actuated down by a cam (24). The cam can be rotated by a suitable motor e.g. a stepper motor. Alternatively, the piston can be actuated by an electromagnet. The stepper motor or electromagnet actuates the piston (21) upon receiving the signal from limit switch (11) with a small delay i.e. piston (21) is actuated after the shut off valves are operated as described before.
The auto braking and shutting of valves can be avoided, if required, by providing a disable switch, which when operated by driver will cut off power supply to stepper motor or electromagnet. Also the disable switch can send a command through microcontroller to deactivate the shut off valves and auto braking.
Method -2 (see Fig.7)
A cylinder (25) with piston (26) in it is connected to brake-fluid line at a location as described in method-1 above. The piston is actuated by the mechanical movement of wheel, similar to the way in which limit switch (11) is actuated as shown in Fig 5. The cylinder (25) is located suitably on one end of the front wheel axle housing. Similarly, another set of cylinder (25a) and piston (26a) are located suitably on the other end of the front wheel axle housing. Either of the above cylinders generates pressure upon full turning of steering wheel. This pressure is transmitted to brake-fluid circuit. The cylinder (25) and (25a) have got dummy pistons (27) and (27a) which are supported by springs (31), (31a), (28) and (28a) respectively as shown in Fig.7. The springs (28) and (28a) are harder compared to springs (31), (31a) and springs of the brake line actuators. The pistons (26) and (26a) are kept pressed on to stoppers (30) and (30a) provided on the cylinders (25) and (25a) respectively.
When auto braking is required to be disabled the driver can operate a switch which will energise a normally open electromagnet type shut-off valve (29) located in the line connecting to main brake fluid line as shown in Fig.7. Once (29) is closed the pressure developed in cylinder (25) or (25a) will not be transmitted. The only requirement in this case is that the driver shall deactivate the auto braking before the
steering wheel is fully turned to its extreme position. If it is turned so, then the driver has to tum the steering little towards normal position from the extreme position and then deactivate auto braking by switching on the deactivating switch.
After turning the steering wheel to any extreme position, driver shall apply normal brake pedal so that the brake circuit is pressuised. The brake shall be applied after the shut-off valves are closed. An indicator light can be put on front panel which glows upon the activation of limit switch (11) or similar limit switch (12) on the left side of the front axle housing. After the indicator glows, the driver can apply brake pedal and turn the vehicle using clutch control while the vehicle is in first gear.
CLAIMS OF THE INVENTION
1. A method for decreasing turning radius of a four wheeled automobile wherein
(i) The rear left wheel is locked or constrained by applying brake only to the said rear left wheel, while keeping the other three wheels in un-braked condition; the said locking shall be done after the steering wheel is completely turned in anticlockwise direction to take U- turn or sharp tum towards the left side.
(ii) The rear right wheel is locked or constrained by applying brake only to the said rear right wheel, while keeping the other three wheels in un-braked condition; the said locking shall be done after the steering wheel is completely turned in clockwise direction to take U-tum or sharp tum towards the right side.
(iii) The said U- turns are effected in a sequence given below.
(a) First tum the steering to the extreme position, in clockwise or anticlockwise
(b) Lock the corresponding rear wheel i.e. Right or Left rear wheel.
(c) Tum slowly by applying accelerator or by clutch control in a suitable gear; preferably in first gear.
2. A system for locking a particular rear wheel of a four wheeled automobile
wherein the hand brake lever for locking only the rear wheels is split into two
independent levers arranged side by side and very closely; each lever when pulled
up independently will apply brakes to corresponding rear wheel wherein
(i) The said independent pulling of the lever is facilitated by extending the lever
on to one side as shown in Fig.3.
and (ii) The levers can be pulled together by spilt knobs attached to said levers located
side by side for normal use of hand brake when vehicle is parked.
3. A system for automatically locking a particular rear wheels of a four wheeled
(i) Four numbers of electrically operated shut-off valves are placed, one on each brake-fluid line to each of the four wheels, just before the brake line actuator.
(ii) Three of the above said shut-off valves i.e. all shut-off valves, except the valve on one of the rear wheel brake fluid lines, are closed on receipt of command from a suitable computer or microcontroller; the said command is given on closure of a limit switch which is activated by the front wheel on the side corresponding to the side on which said shut-off valve is kept open.
(iii) The said limit switch is placed on a leaf spring which in turn is attached to a base; the said base is attached to the front axle housing suitably such that when the wheel (on the side to which the vehicle is to be turned) approaches its extreme position as shown in Fig.l, the said limit switch gets pressed and a signal is sent to computer or an electrical circuit is activated so that all the shut-off valves, except the shut-off valve on the rear to the side to which the vehicle is to be turned, are closed.
(iv) Limit switches are placed on either side of front axle housing in a manner explained in claim 3 (iii).
4. A system for automatically locking a particular rear wheel as claimed in claim 3 wherein the automatic locking or braking of the particular rear wheel is achieved by one of the following three means i.e.
(i) The brake-fluid line is pressurised by connecting a cylinder to it; the said cylinder is pressured by a piston placed in it and the said piston is actuated by a cam attached to a suitable motor e.g. a stepper motor or by a suitable electromagnet; the said stepper motor or electromagnet is actuated by a signal received from the said computer or microcontroller which sends the said signal after the said limit switch is actuated by front wheel and after the said three shut-off valves are closed as described in claim 3(ii).
(ii) The brake-fluid line is pressurized by connecting two cylinders to it which are placed on the either side of the front axle such that one of the pistons, placed in each cylinder, gets actuated by one of the front wheels when it reaches extreme position; the said piston is placed in such a way that its actuation happens after the said limit switch is activated and after the said three shut-off valves are closed as described in claim 3(ii).
(iii) The brake-fluid line is pressurised by applying normal brake pedal after the three shut off valves are closed as described in claim 3(ii); the said closing of shut off valves can be indicated by an indicator bulb placed in front of driver, which glows after the said limit switch is activated by front wheel as described in claim 3 (iii).
5. The system claimed in claim 4 wherein the auto braking can be avoided by an auto braking deactivating switch provided in front driver which when made on shall cut off the supply to said stepper motor, or electromagnet and to the shut-off valves by suitable electrical means directly or through said computer or microcontroller.
6. The system claimed in claim 4(ii) wherein
(i) the automatic braking can be avoided by an auto braking deactivation switch provided in front of driver which when made on shall actuate an electromagnetically operated shut-off valve placed between said cylinders and the main brake fluid line.
(ii) the said automatic braking deactivation switch is to be operated before the steering wheel is turned to its extreme; if the steering wheel is turned to its extreme it shall be turned back little bit towards the normal position and then the said auto braking deactivation switch can be deactivated.
(iii) a dummy piston is located in each of the said cylinders as shown in Fig.7 so that it relieves the pressure generated in the cylinder.
(iv) two springs, one between said dummy piston and cylinder end cover and another between said dummy piston and actuating piston, are placed inside the said cylinder; the spring located between dummy piston and cylinder end cover is harder compared to the spring located in the brake liner assembly against which the brake liners are actuated.
7. A method and system for taking sharper U- turns of a four wheeled vehicle, substantially as here in explained and illustrated in the accompanying drawings.
Summary of the invention
A method and associated system for reducing the turning radius and assisting the vehicle to take U-turns in a lesser road space is proposed. The method is based on the fact that if the rear inner wheel is locked while taking a sharp turn in a direction then the vehicle will take lesser space with centre of rotation nearly located at the locked wheel. The proposed system consists of putting electromagnetically operated shut-off valves on all brake fluid lines to wheels and operating the valves automatically in such a manner so as to lock a particular rear wheel by employing auto braking as well as manual braking. This is essentially useful for four wheeled vehicles with front wheel drive. It also can be used for vehicles with rear wheel drive provided the design of differential and transmission takes the extra loads generated during turning with a rear wheel fully or partially locked.
|Indian Patent Application Number||2405/CHE/2007|
|PG Journal Number||31/2012|
|Date of Filing||24-Oct-2007|
|Name of Patentee||CH. RABI KUMAR|
|Applicant Address||43, Type 3, CPRI Colony, New Bel Road, Bangalore - 560 012.|
|PCT International Classification Number||B62D 7/00|
|PCT International Application Number||N/A|
|PCT International Filing date|