DESC:FORM 2

THE PATENTS ACT, 1970

(39 of 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION

(See Section 10 and Rule 13)

Title of invention:

A SYSTEM FOR STEERING OF A CRAWLER

Applicant:

BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru,
Karnataka - 560 027, India

The following specification describes the invention and the manner in which it is to be performed.

CROSS-REFERENCE TO RELATED APPLICATION AND PRIORITY

[001] The present application claims priority from Indian Patent application no. (201841037391) filed on 3rd October, 2018.

TECHNICAL FIELD

[002] The present subject matter described herein, in general, relates to a system for a crawler. More particularly, the system further relates to steering of the crawler.

BACKGROUND

[003] Generally, in conventional bulldozers or crawlers a steering system is mainly based on sliding motion of a steering and a brake valve spools and springs inside the control valve body. It is to be noted that, the sliding motion of the spools inside the valve body to actuate the clutch depends on the dimensional and geometrical accuracies of the spool and a bore diameter of the valve body, surface finish of the spools, and a valve body. Hence, the conventional Spool type control valve is complicated with more number of components and with more precise machining. Further, it is to be noted that, even slight deviation from the above mentioned factors are greatly influencing that affects the performance of the conventional design of the steering control valve, thus, causing failure of the steering control system viz., spool jamming, failure of the springs.

[004] Consequently, in conventional hydraulic clutch and brake type steering systems, the turning radius and direction of travel of the crawler or bulldozer are entirely dependent on more number of hardware components. For example, in conventional track type crawler devices have a significant mass that have undesirable effects when it is operated on a grade. In another example, when the vehicle is travelling down a grade and the operator requests a gradual left turn, the mass of the vehicle cause increase in velocity and begin a gradual turn to the right. Thus, due to the motion of the vehicle in a direction opposite to the desired direction has obvious repercussions in controllability and in-consistent steering response is an undesirable feature. Thus there is a need overcome the limitation of the conventional steering system of the crawler.

SUMMARY

[005] Before the present a system for steering of a crawler, is described, it is to be understood that this application is not limited to the particular systems, and methodologies described, as there can be multiple possible embodiments, which are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for describing the particular implementations, versions, or embodiments only, and is not intended to limit the scope of the present application.

[006] This summary is provided to introduce aspects related to the system. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[007] In one embodiment, a system for steering of a crawler is disclosed. The system comprises a joystick, a controller, and proportional valves and brake valves. In one embodiment, the joystick is connected to a potentiometer. The potentiometer generates a voltage based on a position of the joystick. In another embodiment, in one aspect, the controller is connected to the potentiometer. In another aspect, the controller generates an instruction signal based on the voltage. In one another embodiment, the proportional valves and the brake valves are connected to the controller. In one implementation, during operation, the proportional valves and the brake valves turn a crawler in one of a left or a right direction based on the instruction signal.
BRIEF DESCRIPTION OF THE DRAWINGS

[008] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating of the present subject matter, an example of construction of the present subject matter is provided as figures; however, the invention is not limited to the specific system disclosed in the document and the figures.

[009] The present subject matter is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.

[0010] Figure 1 illustrates a block diagram of a system for steering a crawler, in accordance with an embodiment of the present subject matter.

[0011] Figure 2 is a graphical illustration of relationship between the stroke or percentage (%) of a joystick movement and the hydraulic pressure of the proportional control valves, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

[0012] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although a system similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, is now described. The disclosed embodiments for the system is merely example of the disclosure, which may be embodied in various forms.

[0013] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments for the system. However, one of ordinary skill in the art will readily recognize that the present disclosure for the system is not intended to be limited to the embodiments described, but is to be accorded the widest scope consistent with the principles and features described herein.

[0014] The present subject matter discloses a system or an apparatus for steering a crawler or a bulldozer. The system comprises a joystick, a controller, and proportional valves and brake valves. In one embodiment, the joystick is connected to a potentiometer. The potentiometer generates a voltage based on a position of the joystick. In another embodiment, in one aspect, the controller is connected to the potentiometer. In another aspect, the controller generates an instruction signal based on the voltage. In one another embodiment, the proportional valves and the brake valves are connected to the controller. In one implementation, during operation, the proportional valves and the brake valves turn a crawler in one of a left or a right direction based on the instruction signal. Explanation of the present subject matter with reference to figures is described in the subsequent embodiments.
[0015] Now, referring to Figure 1, Figure 1 illustrates a system 100 for steering a crawler. In one embodiment, the present subject matter discloses a system 100 for steering a crawler or a bulldozer. The steering system 100 may electronically control hydraulic steering clutches and hydraulic brakes. The steering of the crawler may be in one of a left direction or a right direction.

[0016] In one embodiment, the system 100 comprises a joystick 42, a controller 41, proportional valves (19LS, 19RS), and brake valves (20LB, 20RB). In another embodiment, the joystick 42 may be connected to a potentiometer (not shown). The joystick 42 may be a lever that may move in several directions in order to control a movement of the crawler. The joystick 42 lever or a shaft may be connected to the potentiometer, therefore, when the shaft or the lever of the joystick is pivoted, the shaft rotates a contact arm linked with the shaft of the joystick 42, the contact arm moves along a curved track of the potentiometer comprising a resistor. Further, as the contact arm moves, the resistance of the resistor varies and generates a voltage difference in the circuit. A 24-volt battery may be supplied to the potentiometer to complete the circuit, and the battery may supply the power to the controller 41 to operate.

[0017] This generated voltage difference or voltage signal may be transmitted to the controller 41 connected to the potentiometer. Furthermore, the controller 41 generates an instruction signal based on the received voltage signal. The instruction signal may be one of to activate a left proportional valve 19LS, a right proportional valve 19RS, a left brake valve 20LB, and a right brake valve 20RB. The proportional valves (19LS, 19RS) and brake valves (20LB, 20RB) are connected electrically to the controller. The electrical connection may be by means of electric wires. The proportional valves (19LS, 19RS) and the brake valves (20LB, 20RB) turn the crawler in one of the left direction or the right direction. he proportional valves (19LS, 19RS) and the brake valves (20LB, 20RB) may be known as cartridge type proportional valves.

[0018] In one implementation, during left turn of the crawler, the instruction signal to activate the left proportional valve 19LS is generated, when the joystick 42 is partially tilted to a left direction. In one embodiment, the left proportional valve 19LS is activated for a left steering clutch that may generate a differential pressure of around 1~2 bar in the upstream conduits. The pressure is generated due to an orifice present in the upstream conduits. This may activate a left quick fill valve 21LQ in association with the left proportional valve 19LS to fill a steering clutch piston at faster or a predetermined rate and accordingly the left steering clutch is disengaged, thereby turning the crawler moderately in the left direction. In another embodiment, the left brake valve is activated or is operated, thereby oil flows into a left brake booster that may apply the brake of left drive sprockets 14L, when joystick 42 is shifted more than the predetermined left position, or when the joystick 42 is moved further to the full stroke in the left direction. This leads to a sharp or a faster turning of the crawler in the left direction.

[0019] In another implementation, during right turn of the crawler, the instruction signal to activate the right proportional valve 19RS is generated, when the joystick is partially tilted to a right direction. In one embodiment, the right proportional valve 19RS is activated for a right steering clutch that may generate a differential pressure of around 1~2 bar in the upstream conduits. This may activate a right quick fill valve 21RQ in association with the right proportional valve 19RS to fill a steering clutch piston at faster or a predetermined rate and accordingly the right steering clutch is disengaged, turning the crawler moderately in right direction. In another embodiment, when the joystick is shifted more than the predetermined right position, or when the joystick is moved further to the full stroke in the right direction, the right brake valve is activated or is operated, thereby oil flows into a right brake booster that may apply the brake of right drive sprockets 14R. This leads to a sharp or a faster turning of the crawler in the right direction. A hydraulic pump 18 may supply the hydraulic fluid to various valves present in the system 100.

[0020] Now referring to Figure 2. Figure.2 is a graphical illustration 200 of relationship between the strokes or percentage (%) of the joystick 42 movement and the hydraulic pressure of the proportional valves (19LS, 19RS) for a particular equipment to achieve the required operator comfort and the characteristics can be varied as per the requirement by modifying the programme. The proportional valves (19LS, 19RS) and brake valves (20LB, 20RB) are arranged such a way that may exhibit the hydraulic characteristic that the timing of the rise of hydraulic pressure of the proportional valves 19LS and 19RS for steering clutches is earlier than the brake valves 20LB and 20RB for brakes as shown by the curves in Figure.2. The braking is initiated a predetermined period of time after the steering clutch has been disengaged. The predetermined period of time interval between steering clutch disengagement and the application of brake can be determined based on the operating conditions like downgrading, upgrading or the horizontal movement of the crawler.

[0021] In another embodiment, the system 100 comprises dump valves (22LD, 22RD), the dump valves are normally closed (NC) that is used to drain the steering clutches immediately when the joystick 42 is brought back to its neutral position for making the equipment to travel in the straight track. The neutral position may be between the left position and the right position of the joystick 42.

[0022] In yet another implementation, for the crawler to run or travel in a straight track, the power from an engine 1 is transmitted to an input shaft 6 of the steering unit though a torque convertor 2, then a forward clutch F or a reverse clutch R. Further, the power is transmitted to speed change gears 3a, 3b, 3c or 3d and then through a bevel gear set 5. Furthermore, the power is further transmitted to clutches, output shafts, and brakes for left and right sides respectively (8LC, 8RC, 9L, 9R, 10LB, 10RB) and then to the final drives 14L and 14R via the reduction gears (11L, 11R, 12L 12R) and final output shafts (13L, 13R). Thus, as there is no control signal to the proportional valves (19LS, 19RS) and the brake valves (20LB, 20RB) from the controller 41. The input power is equally distributed to both the drive sprockets (14L, 14R) to make the crawler travel or run in a straight path based on the forward gear, or the crawler may travel in a reverse track based on the reverse gear. A driver by means of the forward clutch or the reverse clutch may operate the forward or reverse gear.

[0023] Exemplary embodiments discussed above may provide certain advantages, these may include the following.

[0024] Some embodiments of the system eliminates the use of more number of hardware components or functional parts and complexity for precise machining of the components.

[0025] Some embodiments of the system eliminates the issue of jamming of the spool as cartridge type valves are used.

[0026] Some embodiments of the system provides quick response for operating the crawler in desired direction based on the instruction signal.

[0027] Some embodiments of the system provides jerk free and smooth operation of the crawler.

[0028] Some embodiments of the system is easy to mount on the crawler, the system is easy to maintain, reduces equipment down time and provides reliable operation, and increased operation comfort for the driver.

[0029] Although implementations for the system 100 have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as examples of implementation for the system 100.
,CLAIMS:1. A system (100) for steering of a crawler, the system (100) comprises:
a joystick (42), wherein the joystick (42) is connected to a potentiometer, wherein the potentiometer is configured generate a voltage based on a position of the joystick (42);
a controller (41) connected to the potentiometer, wherein the controller is configured to generate an instruction signal based on the voltage; and
proportional valves (19LS, 19RS) and brake valves (20LB, 20RB) connected to the controller (41), wherein during operation, the proportional valves (19LS, 19RS) and the brake valves (20LB, 20RB) turn a crawler in one of a left or a right direction based on the instruction signal.

2. The system (100) as claimed in claim 1, wherein the proportional valves (19LS, 19RS) comprises a left proportional valve (19LS) and a right proportional valve (19RS), wherein the brake valves (20LB, 20RB) comprises a left brake valve (20LB) and a right brake valve (20RB), wherein during left turn, the left proportional valve (19LS) and the left brake valve (20LB) is activated, and wherein during right turn, the right proportional valve (19RS) and the right brake valve (20RB) is activated. .

3. The system (100) as claimed in claim 1, wherein the instruction signal to activate the left proportional valve (19LS) is generated, when the joystick (42) is shifted to a predetermined left position.

4. The system (100) as claimed in claim 1, wherein the instruction signal to activate the left brake valve (20LB) is generated, when the joystick is shifted more than the predetermined left position.

5. The system (100) as claimed in claim 1, wherein the instruction signal to activate the right proportional valve (19RS) is generated, when the joystick (42) is shifted to a predetermined right position.

6. The system (100) as claimed in claim 1, wherein the instruction signal to activate the right brake valve (20RB) is generated, when the joystick (42) is shifted more than the predetermined right position.

7. The system (100) as claimed in claim 1, wherein the system (100) comprises a left quick fill valve (21LQ), wherein the left quick fill valve (21LQ) is configured to fill oil in a left steering clutch piston at a predetermined rate based on the activation of the left proportional valve (19LS).

8. The system (100) as claimed in claim 1, wherein the system (100) comprises a right quick fill valve (21RQ), wherein the right quick fill valve (21RQ) is configured to fill oil in a right steering clutch piston at a predetermined rate based on the activation of the right proportional valve (19RS).