Claims:
We claim,
1. A system (100)for controlling lift axle of a vehicle, said vehicle comprising a plurality of mechanically or pneumatically suspended axles with wheels in contact with a ground surface and at least one lift axle (104)with wheels operably moveable between a raised position and a lowered position, said system (100)comprising:
a lift axle controller (128);
a deployment mechanism provided in communication with said lift axle controller (128);
a vehicle speed sensing means (120) for sensing a speed of said vehicle and communicating said vehicle speed to said lift axle controller (128);
a gear transmission sensing means (122) for sensing a selected transmission gear and communicating said selected transmission gear to said lift axle controller (128); and
a steering angle sensing means(124)for sensing a steering angle and communicating said steering angle to said lift axle controller (128);
wherein,
said lift axle controller (128)is adapted to collect and process information received from said vehicle speed sensing means(120), said gear transmission sensing means(122), said steering angle sensing means(124); and
said lift axle controller (128) is adapted to send at least one signal in response to said processed information to actuate one of the lift bag(108)and the load bag (110)to move said lift axle(104)to said raised position and said lowered position, respectively.

2. The system (100) as claimed in claim 1, wherein said lift axle controller (128) is provided in communication with a load sensing valve (106) which is configured to measure a load acting on said vehicle through at least one of electrical and pneumatic of mechanical load sensor, and load detection mechanism.

3. The system (100) as claimed in claim 1, wherein said deployment mechanism includes:
at least one lift bag (108) and at least one load bag (110) in operational communication with said lift axle (104);
a lift bag valve (112) and a load bag valve (114) in operational communication with said lift bag (108) and said load bag (110), respectively;
a fluid source S in communication with said lift bag(108), said lift bag valve(112), said load bag(110), and said load bag valve(114);and
a lift axle control valve (LACV) (116), said lift axle control valve (116) is provided in communication with said lift axle controller (128) and said load sensing valve (106).

4. The system (100) as claimed in claim 1, wherein said system (100) includes an override switch (126), said override switch (126) is provided in communication with said lift axle controller (128) to transmit a status of user selection of the override switch (126).

5. The system (100) as claimed in claim 1, wherein said lift bag valve (112) and said load bag valve (114) is at least an exhaust delay relay valve and a relay valve, respectively.

6. The system (100) as claimed in claim 1, wherein said vehicle speed sensing means (120) is selected from a group consisting of vehicle speed sensor, Electronic communication unit (ECU), GPS based vehicle tracker system and ABS sensor.

7. The system (100) as claimed in claim 1, wherein said gear transmission sensing means (122) is selected from a group consisting of transmission sensor and Electronic control unit (ECU).

8. The system (100) as claimed in claim 1, wherein said steering angle sensing means (124) is selected from a group consisting of, steering angle on steering column, measurement of tie rod movement with respect to an axle beam, steering angle sensor on steering gearbox, CAM on steering column or gearbox, ESP sensor, steering gearbox pressure during turning, and knuckle turning sensor.

9. The system (100) as claimed in claim 4,wherein said status of said override switch (126)is one of ON and OFF condition.

10. The system (100) as claimed in claim 1, wherein said lift axle controller (128) is adapted to achieve one of lifting and lowering of said lift axle (104) based on information related to change between forward motion, reverse motion, and/or stopped condition of the vehicle, change of vehicle speed above and/or below certain predetermined levels, change of vehicle steering angle above and/or below certain predetermined levels and said status of said override switch.

11. The system (100) as claimed in claim 1,wherein said lift axle controller (128) is pre-programmed to receive signals from the gear transmission sensing means (122), then the signals from the vehicle speed sensing means (120), the steering angle sensing means (124), and the override switch (126) and process the information by comparing the same with a standard look up table stored in a memory unit of the lift axle controller (128) where selected gear is first identified used to determine actuating of said lift axle (104).

12. The system (100) as claimed in claim 1, wherein said lift axle controller (128) is pre-programmed to receive signals from the gear transmission sensing means (122), wherein gear based sensing is adapted to eliminate dependency on other sensors like speed sensors and steering angle sensors when said vehicle is moving in higher gear, thereby increasing functional durability of the lift axle controller (128) to lift the lift axle (104) during a wheel drag.

13. The system (100) as claimed in claim 12, wherein said lift axle controller (128) is pre-programmed to receive signals from the gear transmission sensing means (122), wherein said lift axle controller (128) is adapted to eliminate accidental actuation of the lift axle (104) due to malfunctioning of vehicle speed sensing means (120), the steering angle sensing means (124), when said vehicle is travelling at a higher speed.

14. A system (200)for controlling lift axle of a vehicle, said lift axle (104)with said wheels operably moveable between a raised position and a lowered position, said system (200)comprising:
a lift axle controller (128);
a deployment mechanism provided in communication with said lift axle controller (128);
a gear transmission sensing means (122) for sensing a selected transmission gear and communicating said selected transmission gear to said lift axle controller (128);
a vehicle speed sensing means (120) for sensing a speed of said vehicle and communicating said vehicle speed to said lift axle controller (128);
a steering angle sensing means (124) for sensing a steering angle and communicating said steering angle to said lift axle controller (128);and
a first solenoid operated valve (132), a second solenoid operated valve (130), and a third solenoid operated valve (134) provided in communication with said lift axle controller(128),
wherein,
said lift axle controller (128) is adapted to collect and process information received from said gear transmission sensing means (122), said vehicle speed sensing means (120), said steering angle sensing means (124), and transfer signal to one of said first solenoid operated valve (132) to completely release pressure from said load bag (110) when said lift axle (104) is in lowered position (deployed condition);
said second solenoid operated valve (130) adapted to release a predetermined pressure from said load bag (110), when said lift axle (104) is in lowered position (deployed condition); and
said third solenoid operated valve (134) adapted to supply a limited pressure to the lift bag (108) such that it reduces lift axle traction due to unsprung mass, while said wheels of said lift axle (104) are engaged to said ground surface, when said vehicle is in motion.

15. A method (400) for automatically controlling a lift axle (104) in a vehicle, said method(400) comprising:
sensing and communicating by, a gear transmission sensing means (122), an engaged gear to the said axle controller (128);
sensing and communicating by, a vehicle speed sensing means (120), a speed of the vehicle to a lift axle controller (128);
sensing and communicating by, a steering angle sensing means (124), a steering angle of the vehicle to said lift axle controller (128);
communicating by, a manual override switch (126), status of user selection of the override switch (126) to said lift axle controller (128);
collecting and processing, by said lift axle controller (128), information received from said gear transmission means (122),said vehicle speed sensing means (120), said steering angle sensing means (124), and said override switch (126);
actuating a lift axle control valve (116) by said lift axle controller (128) based on the processed information; and
actuating, by said lift axle control valve (116), one of a lift bag (108) and a load bag (110) to move said lift axle (104) to one of said raised position and said lowered position, respectively.

16. A method (500) for automatically controlling a lift axle (104) of a vehicle, said method(500) comprising:
sensing and communicating by, a gear transmission sensing means (122), an engaged gear to said lift axle controller (128);
sensing and communicating by, a vehicle speed sensing means (120), a speed of the vehicle to a lift axle controller (128);
sensing and communicating by, a steering angle sensing means (124), a steering angle of the vehicle to said lift axle controller (128);
communicating by, a manual override switch (126), status of user selection of the override switch (126) to said lift axle controller (128);
connecting a first solenoid operated valve (132) and a second solenoid operated valve (130) in communication with said lift axle controller (128); collecting and processing, by said lift axle controller (128), information received from said gear transmission means (122), said vehicle speed sensing means (120), said steering angle sensing means (124);
actuating said first solenoid operated valve (132) by said lift axle controller (128) based on the processed information, to release complete pressure from said load bag (110) when said lift axle (104) is in lowered position (deployed condition);and actuating said second solenoid operated valve (130) by said lift axle controller (128) based on the processed information, to release a predetermined pressure from said load bag (110) when said lift axle (104) is in lowered position (deployed condition).

17. A method (600) for automatically controlling a lift axle (104) of a vehicle, said method(600) comprising:
sensing and communicating by, a gear transmission sensing means (122), an engaged gear to said lift axle controller (128);
sensing and communicating by, a vehicle speed sensing means (120), a speed of the vehicle to a lift axle controller (128);
sensing and communicating by, a steering angle sensing means (124), a steering angle of the vehicle to said lift axle controller (128);
communicating by, a manual override switch (126), status of user selection of the override switch (126) to said lift axle controller (128);
connecting a first solenoid operated valve (132) and a second solenoid operated valve (130) in communication with said lift axle controller (128); collecting and processing, by said lift axle controller (128), information received from said gear transmission means (122), said vehicle speed sensing means (120), said steering angle sensing means (124);
actuating said first solenoid operated valve (132) by said lift axle controller (128) based on the processed information, to release complete pressure from said load bag (110) when said lift axle (104) is in lowered position (deployed condition); and
actuating the third solenoid operated valve (134) by the lift axle controller (128) based on the processed information, to introduce a predetermined pressure to the lift bag (108) when the lift axle (104) is in lowered position.

18. The steering angle sensing means (124) as claimed in claim 8, wherein said steering angle sensing means (124) is at least a wheel speed sensor used for detecting wheel turning angle.

19. The steering angle sensing means (124) as claimed in claim 8, wherein said steering angle sensing means (124) is at least a corresponding displacement sensed by a displacement sensor (802), said displacement sensor (802) disposed parallel to a hydraulic steering cylinder (720) and said displacement is proportional to a wheel turning angle, said displacement sensor (802) adapted to be positioned in one of external to said hydraulic steering cylinder (720) and internal to said hydraulic steering cylinder (720).
, Description:TECHNICAL FIELD
[001] The embodiments herein generally relate to lift axles of load carrying utility vehicles, and more particularly to systems and methods for automatically controlling a lift axle(s) of a load carrying utility vehicle.
BACKGROUND
[002] Generally, to increase a load carrying capacity of multi-axle commercial vehicles, auxiliary axles are added either in front of a drive axle or rear side of the drive axle. The auxiliary axle is commonly an air suspension system and is raised in un-laden condition, which is therefore called as lift axle. If the auxiliary axle is located in front of the drive axle, then it is called as pusher lift axle. If the auxiliary axle is located at the rear side of the drive axle, then it is called as tag lift axle.
[003] The commercial multi-axle vehicles are configured to carry maximum allowable load. However, when the vehicle is operated in a severe turn or severe undulated road, a lot of severe tire scrub problem is observed in the vehicle having non-steer lift axle. The tires in the lift axle are subjected to severe cornering forces when the vehicle experiences the severe turn. Therefore, it leads to a shoulder scrub or wear in the tires fitted in the lift axle and all non-steered rear axles, which in-turn, reduces the life of the tire drastically. Therefore, in the multi-axle commercial vehicle, it is highly necessary to minimize the shoulder scrub or wear in the tire.
[004] In some conventional approaches, a manually operated traction assistance system is provided in multi-axle coach, tractor trailer and multi-axle truck with the tag and/or pusher non-steer lift axle. In these vehicles, the operator (i.e. driver) has to operate (i.e. switch on) the switch manually when the vehicle is experiencing a severe turn in undulated roads. Thereby, the ride air springs of the auxiliary suspension are deflated for a while and inflated automatically for a pre-described time or speed of the vehicle. When deflating the ride air springs, the reaction load on the auxiliary axle is minimized to the self weight of the axle assembly. The same operation is followed when the vehicle is in reverse condition also. Thereby, the load on the pusher or tag axle is transferred to the remaining axles for a limited period. It greatly helps in minimizing tires shoulder scrub or tire wear, and increasing maneuverability and traction of the vehicle.
[005] In general, the operator follows the manual operation of the switch very rarely in these manual traction assistance systems. Further, the operator may forget to manually operate the switch most of the time especially during severe turn due to the urgency of driving, vehicle reverse condition, undulated road and slippery road, etc. Therefore, practically, the operator (driver) may not operate the manual switch properly or at required time.
[006] The conventional manual operated traction assistance system consists of many electrical and electronics parts, converters etc. Therefore, the cost of manufacturing and maintenance are high and hence, conventional manually operated traction assistance system may not be desirable solution for hauling, i.e. effective traction assistance to the vehicle. In respect of the conventional approaches, the operation of manual switch traction assistance system does not provide complete solution to minimize tires shoulder scrub, maneuverability and traction of the vehicle when the multi-axle vehicle experiences severe turn or severe undulated road.
[007] Therefore, there exists a need for systems and methods for automatically controlling a lift axle(s) of a load carrying utility vehicle, which obviates the aforementioned drawbacks.
OBJECTS
[008] The principal object of the embodiments herein is to provide systems for automatically controlling at least one lift axle of a load carrying utility vehicle such as but not limited to Heavy Commercial Vehicle (HCV), Light Commercial Vehicle (LCV), Intermediate Commercial Vehicle, Medium Commercial Vehicle.
[009] Another object of the embodiments herein is to provide systems for automatically controlling lifting and lowering of at least one lift axle based on predefined terrain and vehicle operating conditions.
[0010] Still another object of the embodiments herein is to provide systems for automatically controlling lifting and lowering of at least one lift axle of the load carrying utility vehicle which is inexpensive and easy to manufacture.
[0011] Yet another object of the embodiments herein is to provide methods for automatically controlling at least one lift axle of a load carrying utility vehicle.
[0012] Another object of the embodiments herein is to provide systems and methods for automatically controlling at least one lift axle of the load carrying utility vehicle, which achieves better traction loss and reduces tire wear.
[0013] Another object of the embodiments herein is to provide systems and methods which improves vehicle stability by reducing load bag pressure in high speed vehicle instead of completely depleting to prevent the vehicle roll.
[0014] Another object of the embodiments herein is to provide systems and methods which provides more safer and stable vehicle handling at high speed, i.e. when the vehicle is operated in high speed driving condition and/or high gear engaged condition, the systems are configured to bypass vehicle speed and vehicle steering angle governed lifting of the lift axle, thereby eliminating errors induced due to malfunctioning of speed and steering angle sensors and hence provide more safer and stable vehicle handling when the vehicle is moving in high speed.
[0015] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0016] The embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0017] FIG. 1 depicts a top view of a load carrying utility vehicle equipped with at least one lift axle, according to an embodiment as disclosed herein;
[0018] FIG. 2 depicts a schematic view of a conventional (existing) lift axle control system, according to an embodiment as disclosed herein;
[0019] FIG. 3 depicts a schematic view of a system for automatically controlling the lift axle of the load carrying utility vehicle, according to an embodiment as disclosed herein;
[0020] FIG. 4 depicts a schematic view of a system for automatically controlling the lift axle of the load carrying vehicle to achieve traction loss, according to an alternate embodiment as disclosed herein;
[0021] FIG. 5 depicts a schematic view of a system for automatically controlling the lift axle of the load carrying utility vehicle to achieve traction loss, according to another alternate embodiment as disclosed herein;
[0022] FIG. 6 is a schematic illustration of signals received and generated by the system (100) for automatically controlling the lift axle in the load carrying utility vehicle, according to an embodiment as disclosed herein;
[0023] FIG. 7 is a flowchart showing a method for automatically controlling a lift axle in a load carrying utility vehicle, according to an embodiment as disclosed herein;
[0024] FIG. 8 is a flowchart showing a method for controlling a lift axle automatically to avoid traction loss at rear axle(s) of the load carrying utility vehicle, according to an alternate embodiment as disclosed herein;
[0025] FIG. 9 is a flowchart showing a method (600) for controlling a lift axle automatically to avoid traction loss at rear axle(s) of the load carrying utility vehicle, according to another alternate embodiment as disclosed herein;
[0026] FIG. 10 is a flowchart depicting a method of using a wheel speed sensor as steering angle sensing means, according to an embodiment as disclosed herein;
[0027] FIG. 11 depicts a path followed by wheel on the axle from start of a turn, according to an embodiment as disclosed herein;
[0028] FIG. 12 depicts a skeletal system of a twin steering system steered by a driver in the load carrying utility vehicle, according to an embodiment as disclosed herein; and
[0029] Fig. 13 depicts an enlarged view of steering hydraulic cylinder with a displacement sensor mounted externally, according to an embodiment as disclosed herein.

DETAILED DESCRIPTION
[0030] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0031] The embodiments herein achieve systems for automatically controlling a lift axle of a load carrying utility vehicle. Further, the embodiments herein achieve systems for automatically controlling lifting and lowering of the lift axle based on predefined terrain and vehicle operating conditions. Furthermore, the embodiments herein achieve methods for automatically controlling the lift axle of the load carrying utility vehicle. Referring now to the drawings, and more particularly to Figs. 1through 13, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0032] FIG. 1 depicts atop view of a load carrying utility vehicle equipped with at least one lift axle, according to an embodiment as disclosed herein. FIG. 2 depicts a schematic view of a conventional (existing) lift axle control system, according to an embodiment as disclosed herein. A conventional load carrying utility vehicle (not shown) can be any vehicle configured to haul large and varying loads. The vehicle includes a chassis (not shown) with front and rear mechanically or pneumatically suspended axles which in turn have wheels mounted thereon to support chassis above a road or ground surface. The chassis carries a body (not shown) including a driver cab (22) and a cargo body (not shown). As the load carried by vehicle varies it can be advantageous to lower a supplementary axle to avoid having the vehicle violate per axle loading limitations. Here a lift axle is provided as such a supplementary axle. Those skilled in the art understand that full time use of such lift axle raises the vehicle operating costs due to increased rolling resistance, hence lift axle is lifted when there is no load or partial load is there.
[0033] Automatic control operation of the lift axle, or, alternatively, giving indication to an operator of appropriate times to raise or lower the lift axle, involves other vehicle systems which are schematically illustrated in FIG. 2. The vehicle (not shown)includes a plurality of mechanically or pneumatically suspended axles (not shown)with wheels (not shown) in contact with the ground surface, at least one lift axle (not shown)with wheels (not shown) operably moveable between a raised position and a lowered position, a link which is connected to axle (not shown)or deflecting lever in communication with a load sensing valve(24), at least one lift bag(26)in operational communication with the lift axle, at least one load bag (28)in operational communication with the lift axle, a lift bag valve (EDRV- Exhaust delay relay valve)(30)in operational communication with the lift bag(26)and a load bag valve (Relay valve) (32)in operational communication with the load bag (28), a fluid source (S) (compressed air)in communication with the lift bag(26), the lift bag valve (EDRV- Exhaust delay relay valve)(30), the load bag(28), and the load bag valve(Relay valve) (32), and a lift axle control valve (LACV) (34)in communication with the load sensing valve (24).
[0034] For the purpose of this description and ease of understanding, the conventional lift axle is explained herein below with reference to providing a control system for lifting and lowering of the lift axle of the load carrying vehicle. However, it is also within the scope of the invention to assemble the control system in any other system or machine without otherwise deterring the intended function of lifting as can be deduced from the description and corresponding drawings.
[0035] In an embodiment, the control system for lifting or lowering the conventional lift axle includes the load sensing valve (24) which is actuated based on a load on the axles of the vehicle. The load on the axles of the vehicle is measured by change in a lever angle. The change in the lever angle modulates a pressure output at the load sensing valve (24) (hereafter used as LSV in this description). The pressure output generated at the LSV (24) is supplied to the lift axle control valve (34) (hereafter used as LACV in this description). The LACV (34) is an electro-pneumatic valve which is adapted to determine whether to supply the compressed air to the lift bag (26) through an exhaust delay relay valve (EDRV) or supply the compressed air to the load bag (28) through a relay valve (RV). Further, the conventional system may include a manual control assembly (not shown) operatively coupled to the lift control valve assembly (34). The manual control assembly includes an input, such as a switch (not shown), for actuating the lift axle to move to a raised or lowered position.
[0036] In the conventional lift axle system, the lift axle may include a rolling lobe main air spring which is inflated or deflated by the control system. The main air spring is connected to the compressed air source through relay valve. The compressed air source and the valve cooperate to control the pressure within the main air spring, which in turn controls the spring rate of the main air spring. There is a requirement in the conventional lift axle control system to maintain a residual pressure in the rolling lobe main air spring (Load air spring) to enable a rubber membrane rolling on a piston when the lift axle is in raised condition. To maintain the residual pressure in the main air spring of the lift axle in the raised condition a combination of 3/2 pilot operated valve (36)with pressure regulator valve (70) is connected between the LACV (34) and the main air spring. The 3/2 pilot operated valve (36)includes ports numbers 4, 1 and 3 facing in a first direction and a port 2 facing in a second direction which is opposite to the first direction. In an embodiment, port orientation can be of varied combination. When the LACV (34)supplies the pressure to EDRV to raise the lift axle, a same amount of pressure flows to the port number 4 of 3/2 pilot operated valve which in-turn connects the port number 1 of 3/2 pilot operated valve(36) to the port number 2 which further blocks the port number 3. This arrangement facilitates in supplying the residual pressure to the main air spring which is regulated by the pressure regulator valve (70). Further, when there is no pressure supplied to the EDRV, the same is sensed at port number 4 of 3/2 pilot operated valve(36), which in-turn connects the port number 3 with the port number 2 which further blocks the port number 1. This arrangement facilitates in supplying an actual pressure required to the main air spring. The control assembly controls operation of the LACV (34) to selectively supply compressed air from the compressed air supply to the lift one of the lift bag (26) and the load bag (28).
[0037] FIG. 3 depicts a schematic view of a system (100) for automatically controlling the lift axle of the load carrying utility vehicle, according to an embodiment as disclosed herein. In an embodiment, the system (100) is adapted for automatically controlling the lifting and lowering of the lift axle of the load carrying vehicle. Further, the system (100) is configured to effectively and easily support functionality of the lift axle and enabled to overcome limitations of conventional systems. In an embodiment, the system (100) can also be retrofitted on existing vehicles with minor vehicle modifications.
[0038] In an embodiment, the system (100)is provided in communication with a load sensor (not shown), a load sensing valve (106), a deployment mechanism having a lift bag valve (112), a load bag valve (114), a lift axle control valve (116) (hereinafter called as LACV), a pilot operated valve (118), a vehicle speed sensing means (120), a gear transmission sensing means (122), a steering angle sensing means (124), an override switch (126), a lift axle controller (128), a first solenoid operated valve (132) and a second solenoid operated valve (130). In an embodiment, the system (100) is operatively provided in communication with a lift axle (104).
[0039] The link which is connected to axle (not shown) is provided in communication with the load sensing valve(106).In an embodiment, a single or plurality of load sensors may be assembled at predetermined locations on the vehicle to ascertain the entire load acting on the fixed axles and the lift axle(104) of the vehicle. The load sensor is configured to measure a load and transfer the measured load data to the lift axle controller (128) of the system (100).Based on the measured data the lift axle controller (128) is configured to operate the Lift Axle Control valve LACV (116). The LACV (116) is an electro-pneumatic valve which is adapted to supply a pressure to the lift bag (108) through an exhaust delay relay valve (EDRV) or supply pressure to the load bag (110) through a relay valve (RV).In an embodiment, the lift bag valve (112) and the load bag valve (114) is at least an exhaust delay relay valve and a relay valve, respectively.
[0040] The system (100) is provided in communication with the deployment mechanism which includes the lift bag (108), the load bag (110), lift bag valve (112) and a load bag valve (114). The lift bag (108) and the load bag (110) are provided in operational communication with the lift axle (104). The lift axle controller (128) is in operative communication with the deployment mechanism which serves the function of enabling the lifting and lowering of the lift axle (104). In an embodiment, air springs may also be used and are included in the scope of the present invention as equivalents of load bag (110) and lift bag (108). A pilot operated valve (118) is connected between the lift axle control valve (116) and the air springs to maintain a residual pressure in the air springs. Further, the lift bag valve (112) and the load bag valve (114) are provided in operational fluid communication with the lift bag (108) and the load bag (110), respectively. A fluid source S is provided in fluid communication with the lift bag (108), the lift bag valve (112), the load bag (110) and the load bag valve (114). The valves (112) and (114) are adapted for releasing air from the respective bag (108) and (110) when actuated by the lift axle controller (128). Further the valves (112) and (114) are in operational communication with the fluid source S for filling the load bag (110) or the lift bag (108) when actuated by the lift axle controller (128).The lift axle controller (128) is adapted to control the operation of the valves (112) and (114) to selectively supply compressed air from the fluid source S to the lift bag (108) and the load bag (110).
[0041] The lift axle controller (128) is provided in communication with the gear transmission sensing means (122). During the vehicle operation, the gear transmission sensing means (122) senses engaged gear of the vehicle and transfers a signal to the lift axle controller (128) indicating the engaged gear. When the signal indicate that the vehicle is moving in predetermined higher speed gear, the lift axle controller (128) controls the LACV (116) to move the lift axle (104) from the raised position to the lowered position (deployed position).To deploy the lift axle (104), the lift axle controller (128) controls the LACV (116) to vent air from the lift bag (108) and provide compressed air to the load bag (110). The compressed air supplied to the load bag (110) expands the load bag (110), which in combination with the venting of air from the lift bag (108) displaces the wheels to contact the ground surface. Further, when the signal indicates that the vehicle is moving in a lower speed gear i.e. lower than the predetermined gear, the lift axle controller (128) controls the LACV (116) to move the lift axle (104) from the lowered position to the raised position. The lift axle controller (128) controls the LACV (116) to supply compressed air from the source S to the lift bag (108) and optionally vent air from the load bag (110). The increase in pressure with the lift bag (108) and the optionally reduced pressure in the load bag (110) raises the wheel so that the wheels disengage from the ground surface and, therefore, do not carry any of the weight of the load carrying vehicle. The gear transmission sensing means (122) is selected from a group consisting of transmission sensor and ECU. The ECU of the vehicle is configured to identify the operating gear based on input and output speed of transmission gear ratio. In an embodiment, the gear based sensing is adapted to eliminate dependency on other sensors like speed sensors and steering angle sensors when said vehicle is moving in higher gear, thereby increasing functional durability of the lift axle controller (128) to lift the lift axle (104) during wheel drag.
[0042] The lift axle controller (128) is provided in communication with the vehicle speed sensing means (120). During the vehicle operation, the vehicle speed sensing means (120) senses a speed of the vehicle and transfers a signal to the lift axle controller (128) indicating the speed of the vehicle. When the signal indicate that the vehicle speed has reached a predetermined cruise speed, the lift axle controller (128) controls the LACV (116) to move the lift axle (104) from the raised position to the lowered position (deployed position).To deploy the lift axle (104), the lift axle controller (128) controls the LACV (116) to vent air from the lift bag (108) and provide compressed air to the load bag (110). The compressed air supplied to the load bag (110) expands the load bag (110), which in combination with the venting of air from the lift bag (108) displaces the wheels to contact the ground surface. Further, when the signal indicate that the vehicle speed has reached lower than the predetermined cruise speed, the lift axle controller (128) controls the LACV (116) to move the lift axle (104) from the lowered position to the raised position. The lift axle controller (128) controls the LACV (116) to supply compressed air from the source S to the lift bag (108) and optionally vent air from the load bag (110). The increase in pressure with the lift bag (108) and the optionally reducing pressure in the load bag (110) raises the wheel so that the wheels disengage from the ground surface and, therefore, do not carry any of the weight of the load carrying vehicle. In an embodiment, the vehicle speed sensing means (120) is selected from a group consisting of vehicle speed sensor, Electronic communication unit (ECU), GPS based vehicle tracker system and ABS sensor.
[0043] The lift axle controller (128) is provided in communication with steering angle sensing means (124). During the vehicle operation, the steering angle sensing means (124)senses a steering angle and transfers a signal to the lift axle controller (128) indicating the angle at which the vehicle is steered. When the signal indicates that the steering is in predetermined angle values, the lift axle controller (128) controls the LACV (116) to move the lift axle (104) from the lowered position to the raised position. The lift axle controller (128) controls the LACV (116) to supply compressed air from the source S to the lift bag (108) and optionally vent air from the load bag (110). The increase in pressure with the lift bag (108) and the optionally reduced pressure in the load bag (110) raises the wheel so that the wheels disengage from the ground surface and, therefore, do not carry any of the weight of the load carrying vehicle. Further, when the signal indicates that the steering is less than predetermined angle values, the lift axle controller (128) controls the LACV (116) to move the lift axle (104) from the raised position to the lowered position. The lift axle controller (128) controls the LACV (116) to supply compressed air from the source S to the load bag (110) and optionally vent air from the lift bag (108). The increase in pressure with the load bag (110) and the optionally reduced pressure in the lift bag (108) lowers the wheel so that the wheels engage on the ground surface. In an embodiment, said steering angle sensing means (124) is selected from a group consisting of wheel speed sensor, steering angle on steering column, measurement of tie rod movement with respect to an axle beam, steering angle sensor on steering gearbox, CAM on steering column or gearbox, Electronic stability control (ESP) sensor, steering gearbox pressure during turning, displacement sensor located at hydraulic cylinder and knuckle turning sensor.
[0044] Further, the lift axle controller (128) is in operative communication with a manual override mechanism (not shown) that enables an operator to manually lift or lower the lift axle without considering the vehicle load weight condition. The manual override mechanism includes an override switch (126). A status of this override switch 126 is transferred as a signal to the lift axle controller (128).The override switch (126) is provided in communication with the lift axle controller (128) to transmit a status of user selection of the override switch (126).In an embodiment, the status of the override switch (126) is one of ON and OFF condition.
[0045] The lift axle controller (128) is pre-programmed to receive the signals from the vehicle speed sensing means (120), the gear transmission sensing means (122), the steering angle sensing means (124), and the override switch (126) and process the information by comparing the same with a standard look up table stored in a memory unit of the lift axle controller (128). Based on the comparison between actual measured values from the vehicle speed sensing means (120), the gear transmission sensing means (122), the steering angle sensing means (124), and the override switch (126) and the information stored in the memory unit, the lift axle controller (128) is adapted to control the operation of the valves (112) and (114)to selectively supply compressed air from the source S to the lift bag(108)or the load bag (110).
[0046] For example, the lift axle controller (128) may store the below standard look up table having predetermined values for processing the received signals and perform the control operation. The values provided here are for illustration purpose only. The actual may change based on actual vehicle trails.
Lift axle logic in vehicle laden condition
Step Input Required Gear Criteria Option 1. Lift Axle Lift
Option 2. Load bellow Pressure release
Option 3. Load bellow pressure reduction
Option 4. Load bellow Pressure release+ Lift bellow partial pressurizing Lift Axle Deployed
Step No 1 Identify engaged gear Set 1- (Crawler OR Reverse) Yes No
Set2- (Neutral gear to 6th gear) Based on Step-2 logic
Set 3- (7th gear and above) Based on Step-2 logic
Step No 2 Identity vehicle speed Set-1 (0 kmph to 15 kmph) Based on step-3 logic
Set-2 (15.1 kmph to 30 kmph) Based on step-3 logic
Set-3 (Above 30 kmph) No Yes
Step No 3 Steering wheel angle =180 degree and Set-1 vehicle speed Yes No
=310 degree and Set-2 vehicle speed Yes No

[0047] According to the above exemplary standard look up table, the lift axle controller (128) is adapted to lift the lift axle (104) when the vehicle is moving in first set of gear. The first set of gears are crawler gear and reverse gear. When the vehicle is moving in the first set of gear, wheels associated with the lift axle add traction and increases tire wear when vehicle is steered in this condition. Thus, to avoid additional traction and tire wear, the lift axle controller (128) automatically raises the lift axle (104) from lowered position to raised position. Further, when the vehicle is moving in a second set of gear (i.e. from neutral to 6th gear), the lift axle controller (128) is configured to consider the speed at which the vehicle is moving. When the speed of the vehicle is in a first speed set which ranges from 0 kmph to 15 kmph, the lift axle controller (128) is adapted to consider a first steering angle value which is =180. If the first steering angle value is =180 degree and the vehicle is moving in the first speed set speed, the lift axle controller (128) is configured to raise the lift axle (104) from lowered position to raised position and vice versa when the first steering angle is = 180 degree. Further, when the speed of the vehicle is in a second speed set which ranges from 15.1 kmph to 30 kmph, the lift axle controller (128) is adapted to consider a second steering angle value which is =310. If the second steering angle value is =310 degree and the vehicle is moving in second speed set, the lift axle controller (128) is configured to raise the lift axle (104) from lowered position to raised position and vice versa when the first steering angle is = 310 degree. Further, when the vehicle is moving in a third set of gear (i.e. from 7th and above), the lift axle controller (128) is configured not to raise the lift axle (104) from lowered position to raised position, and hence lift axle remains deployed and tyres remain on ground/road irrespective of steering angle value. Thus, the lift axle controller (128) automatically controls the lifting and the lowering of the lift axle (104) based on predefined terrain and the vehicle operating conditions in laden condition.
[0048] FIG. 6 is a schematic illustration of signals received and generated by the system (100) for automatically controlling the lift axle in the load carrying utility vehicle, according to an embodiment as disclosed herein. Automatic control of lifting and lowering of the lift axle (104) is implemented by programming the lift axle controller (128). The instructions generated by lift axle controller (128) may be coded as messages and broadcasted over private bus. The lift axle controller (128) is adapted to communicate with at least all of vehicle control sensing means through controller area network. An external data storage means (such as a data server, the Cloud, and so on), may also be provided in communication with the lift axle controller (128). The communication may further happen by at least one wireless means for communication, such as, but not limited to, radio, Wi-Fi, satellite, line of sight means, and so on. In an embodiment, the lift axle controller (128) is adapted to perform one of lifting and lowering of the lift axle (104) based on information related to change between forward motion, reverse motion, and/or stopped condition of the vehicle, change of vehicle speed above and/or below certain predetermined levels, change of vehicle steering angle above and/or below certain predetermined levels and said status of the override switch.
[0049] FIG. 4 depicts a schematic view of a system (200) for automatically controlling the lift axle of the load carrying vehicle to achieve traction loss, according to an alternate embodiment as disclosed herein. In an alternate embodiment, the system (200) includes first solenoid operated valve (132) which is provided in communication with the lift axle controller (128) to achieve traction loss. The lift axle controller (128) is adapted to collect (or receive) and process information received from the vehicle speed sensing means (120), the gear transmission sensing means (122), the steering angle sensing means (124), and transfer at least one signal to the first solenoid operated valve (132) to completely release pressure from the load bag (110) when the lift axle (104) is in lowered position (deployed condition).The pressure in the load bag (110)is released without raising the wheel so that the wheels are engaged to the ground surface, thereby achieving the traction loss.
[0050] The system (200) further includes the second solenoid operated valve (130) which is provided in communication with the lift axle controller (128) to achieve traction loss by partial exhaust of the air in the load bag (110). The lift axle controller (128) is adapted to collect and process information received from the vehicle speed sensing means (120), the gear transmission sensing means (122), the steering angle sensing means (124), and transfer at least one signal to the second solenoid operated valve (130) to release a predetermined pressure (air) from the load bag (110) when said lift axle (104) is in lowered position (deployed condition). The pressure in the load bag (110) is released to a predetermined value without raising the wheel so that the wheels are engaged to the ground surface, thereby achieving the traction loss.
[0051] FIG. 5 depicts a schematic view of a system for automatically controlling the lift axle of the load carrying utility vehicle to achieve traction loss, according to another alternate embodiment as disclosed herein. In another alternate embodiment, the system (200) further includes a third 3/2 solenoid operated valve (134) which is provided in communication with the lift axle controller (128). When the controller (128) energizes the third 3/2 solenoid valve (134) which is used along with pressure limiting valve it supplies a limited pressure to the lift bag (108) which further reduces axle reaction due to unsprung mass and further reduces the tire wear. According to this alternate embodiment, The actuation of third 3/2 solenoid valve (134) occurs along with the actuation of first 3/2 solenoid valve (132) i.e. all pressure from the load bag (110) is released due to actuation of the first 3/2 solenoid valve (132) while the wheels of the lift axle (104) remains engaged on the ground surface due to gravitational force on unsprung mass. Further, the limited pressure supplied to the lift bag (108) such that lift axle remain deployed and will not raises the wheel of the lift axle (104) off the ground surface so that the wheels remain engaged to the ground surface, and thereby minimizing wheel traction to very minimal value and preventing the tire wear without lifting the lift axle (104) in moving vehicle.
[0052] FIG. 7 is a flowchart showing a method (400) for automatically controlling a lift axle (104) in a load carrying utility vehicle, according to an embodiment as disclosed herein. The method (400) includes sensing and communicating by, a gear transmission sensing means (122),an engaged gear to the lift axle controller (128) (At step 402). Further The method(400) includes sensing and communicating by, a vehicle speed sensing means (120), a speed of the vehicle to a lift axle controller (128),(At step 404). Furthermore, the method (400)includes sensing and communicating by, a steering angle sensing means (124),a steering angle of the vehicle to the lift axle controller (128) (At step 406). Moreover, the method (400) includes communicating by, a manual override switch (126), status of user selection of the override switch (126) to the lift axle controller (128) (At step 408). The method (400) includes collecting and processing, by the lift axle controller (128), information received from the vehicle speed sensing means (120), the gear transmission means (122), the steering angle sensing means (124), the override switch (126), (At step 410). The method 400 includes actuating the lift axle control valve (116) by the lift axle controller (128) based on the processed information, (At step 412). The method (400) includes, actuating, by the lift axle control valve (116), one of a lift bag (108) and a load bag (110) to move the lift axle(104) to one of a raised position and a lowered position, respectively, based on the signal from the lift axle controller (128), (At step 414).
[0053] FIG. 8is a flowchart showing a method (500) for controlling a lift axle automatically to avoid traction loss at rear axle(s) of the load carrying utility vehicle, according to an alternate embodiment as disclosed herein. The method (500) includes sensing and communicating by, a gear transmission sensing means (122),an engaged gear to the lift axle controller (128) (At step 502). Further, the method(500) includes sensing and communicating by, a vehicle speed sensing means (120), a speed of the vehicle to a lift axle controller (128), (At step 504). Furthermore, the method (500) includes sensing and communicating by, a steering angle sensing means (124), a steering angle of the vehicle to the lift axle controller (128) (At step 506).Moreover, the method (500) includes communicating by, a manual override switch (126), status of user selection of the override switch (126) to the lift axle controller (128) (At step 508). The method (500) includes connecting a first solenoid operated valve (132) and a second solenoid operated valve (130) in communication with the lift axle controller (128) (At step 510). The method (500) includes collecting and processing, by the lift axle controller (128), information received from the vehicle speed sensing means (120), the gear transmission means (122), the steering angle sensing means (124), (At step 512). The method (500) includes actuating a first solenoid operated valve (132)by the lift axle controller (128) based on the processed information, to release complete pressure from the load bag (110) when the lift axle (104) is in lowered position (deployed condition) (At step 514). The method (500) includes actuating a second solenoid operated valve (130) by the lift axle controller (128) based on the processed information, to release a predetermined pressure from the load bag (110) when the lift axle (104) is in lowered position (deployed condition) (At step 516).
[0054] FIG. 9 is a flowchart showing a method (600) for controlling a lift axle automatically to avoid traction loss at rear axle(s) of the load carrying utility vehicle, according to another alternate embodiment as disclosed herein. The method (600) includes sensing and communicating by, a gear transmission sensing means (122),an engaged gear to the lift axle controller (128) (At step 602). Further, the method(600) includes sensing and communicating by, a vehicle speed sensing means (120), a speed of the vehicle to a lift axle controller (128), (At step 604). Furthermore, the method (600) includes sensing and communicating by, a steering angle sensing means (124), a steering angle of the vehicle to the lift axle controller (128) (At step 606). Moreover, the method (600) includes communicating by, a manual override switch (126), status of user selection of the override switch (126) to the lift axle controller (128) (At step 608). The method (600) includes connecting a first solenoid operated valve (132) and a third solenoid operated valve (134) in communication with the lift axle controller (128) (At step 610). The method (600) includes collecting and processing, by the lift axle controller (128), information received from the vehicle speed sensing means (120), the gear transmission means (122), the steering angle sensing means (124), (At step 612). The method (600) includes actuating a first solenoid operated valve (132) by the lift axle controller (128) based on the processed information, to release complete pressure from the load bag (110) when the lift axle (104) is in lowered position (deployed condition) (At step 614),and the method(600) includes actuating a third solenoid operated valve (134) by the lift axle controller (128) based on the processed information, to introduce a predetermined pressure to the lift bag (108) when the lift axle (104) is in lowered position (deployed condition) (At step 616).
[0055] FIG. 10 is a flowchart depicting a method of using a wheel speed sensor as steering angle sensing means, according to an embodiment as disclosed herein. The method (1000) includes disposing at least one ABS sensor or wheel speed sensor on predetermined axle, wherein said ABS sensor or wheel speed sensor is configured to measure Left Hand and Right Hand wheel speeds and transfer an input signal to the lift axle controller (128) (step 1002). In an embodiment, 4 wheel speed sensors may be disposed on the vehicle, wherein 2 may be disposed at front axle and 2 may be disposed at the rear axle. The input signal may be transferred to the lift axle controller (128) from any one sensor axle or combination. The method (1000) further includes, processing the input signal, by the lift axle controller (128) for estimating a vehicle turning direction and angle from a logic (not shown) based on a speed difference (step 1004). The method (1000) further includes, using the estimated steering angle, by the lift axle controller (128) for determining the steering angle of the vehicle (step 1006).
[0056] FIG. 11 depicts a path followed by wheel on the axle from start of a turn, according to an embodiment as disclosed herein. When a vehicle takes a turn the light hand wheel (WHEELLH) travels in an arc (LLH) and the right-hand wheel (WHEELRH) travels in an arc (LRH).The vehicle takes turn in an angle “?” which is a wheel turning angle. Relation between wheel turning angle and wheel speed is derived using below relation:
LLH= ? * a
LRH = ? * (a+b)
Which gives,
? = ( VRH - VLH) * t/ b
Since, VRH =2*p*RRH*nRH/t and VLH = 2*p*RLH*nLH/t
Since RRH=RLH=R, we get,
? = 2*p*R*(nRH - nLH )/b
Since 2*p*R/b = Constant = k
? = k*(nRH - nLH )
Where,
LRH= Distance travelled by RH wheel
LLH= Distance travelled by LH wheel
VRH= Wheel speed at radius RRH
VLH= Wheel speed at radius RLH
? = Wheel turning angle
O = Point about which vehicle takes turn
a = LHS wheel distance from center of turning
b = wheel track
RRH = RHS wheel Radius
RLH = LHS wheel Radius
nRH = Number of rotation of RHS wheel
nLH = Number of rotation of LHS wheel
t = total time of turn
Thus, wheel speed sensed by the wheel speed sensor is used for detecting the turning angle. The turning angle detected by the wheel speed sensor is transferred as an input to the lift axle controller (128) to at least raise the lift axle (104) from the lowered position.
[0057] FIG. 12 depicts a skeletal system of a twin steering system steered by a driver in the load carrying utility vehicle, according to an embodiment as disclosed herein. In an embodiment, the load carrying utility vehicle includes a first front axle and a second front axle, wherein both are steerable by a steering wheel (702).When the driver steers the steering wheel (702), the steering inputs are transferred to the first front axle (FA1) through steering linkages namely a primary drop arm (704), a primary drag link (706), primary steering arm (708). Further, the second front axle (FA2) is steered by an intermediate drag link (710), a second drop arm (712), a second drag link (714), a second steering arm (716), a tie rod arm (718), and a hydraulic cylinder (720). In an embodiment, the hydraulic cylinder (720) works as a force assistance to reduce steering effort. In an embodiment, displacement of a piston within the hydraulic steering cylinder (720) is proportional to the wheel turning angle.
[0058] Fig. 13 depicts an enlarged view of steering hydraulic cylinder with a displacement sensor mounted externally, according to an embodiment as disclosed herein. In an embodiment, a displacement sensor (800) having a body (802) is mounted on to a cylinder body (720a) of the hydraulic steering cylinder (720). Further, the displacement sensor (802) includes a connecting element (804) which is disposed parallel to an axis of hydraulic steering cylinder (720). The connecting element (804) is anchored to an anchor point (806) on piston rod mounting (808) at one end and is connected to the displacement sensor body (802) at the other end. When the tire takes turn with an angle “?” the corresponding displacement is sensed by the displacement sensor (800). The piston of the hydraulic steering cylinder (720) is displaced in proportional to the wheel turning angle. A predetermined relation between wheel angle and displacement of hydraulic steering cylinder (720) is stored in the lift axle controller (128). Once displacement of the piston is sensed, the wheel turning angle is calculated by the lift axle controller (128) and same is used for performing at least one of lifting and lowering of lift axle. In an alternate embodiment, the displacement sensor may be placed internally within the hydraulic steering cylinder (720) which senses the piston displacement with respect to the cylinder body (720a).Thus the wheel turning angle is used for calculating the steering angle and the lift axle controller (128) performs at least a raising or lowering of the lift axle (104) based on the steering angle.
[0059] The advantages provided by the embodiments herein include increased tire life, and reduction in traction effect of the tires.
[0060] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.