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 LIFT AXLE CONTROL SYSTEM FOR A VEHICLE

Applicant:
Tata Motors Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400001,
Maharashtra, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application claims priority from Indian Patent application no. (201921012866) filed on 30th March, 2019.
FIELD OF THE INVENTION
[002] The present subject matter described herein generally relates to a lift axle control system for a vehicle, and more specifically to a lift axle control system for a vehicle like heavy trucks that carry rated load.
BACKGROUND
[003] A lift axle is an auxiliary axle, which is used in heavy trucks to carry rated load. The lift axle can be automatically raised or lowered based on load conditions in the vehicle. The lift axle is lifted up to reduce the tyre wear during unladen condition. The lift axle can also be lifted with traction switch (Manual over-ride) or with reverse gear engagement, for better steerability during laden. The lift axle will, also be lowered during ignition OFF condition, irrespective of load in the vehicle, for anti-theft feature. The existing lift axle system consists of a lift axle and a control system.
[004] Fig. 2 shows the typical schematic of an existing lift axle control system. The lift axle control system consists of one auto load sensing valve (ALSV) or load detection valve (LDV) and one lift axle control valve (LACV), an air reservoir, a lift bellows and a suspension bellows. The lift axle control valve (LACV) is the heart of pneumatic lift axle control system. It has two supply (11, 12), two delivery ports (21, 22) and exhaust port (3), as follows.
11- Control port from ALSV
12- Supply port from reservoir
3- Exhaust
21- Suspension delivery to Suspension bellows
22- Lift delivery to lift bellows
[005] The Auto load sensing valve (ALSV) or load detection valve (LDV) is pneumatic valve, which has two pneumatic ports- supply port (denoted by no. 1) and delivery port (denoted by No. 2). Supply port is connect to air reservoir and delivery port is connected to port 11 of LACV. The lift axle control valve (LACV) is an electro-pneumatic valve which has two supply ports -11, 12, two delivery ports - 21, 22 and one exhaust port 3. This valve is fitted on chassis and its lever is connected to drive axle. The LACV Supply port 11 is connected to delivery port of Auto load sensing/ load detection valve and delivery port 21 is connected to main or suspension bellows. The LACV Supply port 12 is connected to air reservoir and delivery port 22 is connected to lift bellows. The change in load in the vehicle, causes the change in ride height of chassis which causes the ALSV/LDV lever movement in upward or downward direction. This causes the change in ALSV/LDV delivery pressure. Based on pressure value at port no. 11 of LACV, the LACV depletes the suspension bellow and inflate the lift bellow or vice versa.
[006] Since the ALSV/LDV lever is connected to drive axle, due to road irregularities, the ALSV lever keeps on moving in up & down direction. This causes the fluctuations of the pressure at port 11, however this doesn’t cause immediate change in position of lift axe as there is time delay feature of LACV. However due to continuous up & down movement of ALSV lever, there is frequent exhaust from ALSV, which causes excess air consumption.
[007] Also, when axle is in lift condition & brake are applied, the brake chambers, fitted on the lift axle are actuated (supplied with air), however this actuation of brake chamber does not contribute to braking action of vehicle as the axle is in lifted condition and there is no contact between the wheels and road surface.
[008] Whenever there is change in axle position (lifted or deployed), air from either the lift bellows or the suspension bellows is exhausted to the atmosphere. All the above condition causes excess consumption of compressed air. Which in turn cause higher duty cycle of the air compressor & poor fuel economy of the vehicle. Therefore the present invention seeks to overcome the shortcomings associated with the prior arts.
[009] Therefore a lift axle control system for the vehicle is desired that overcome the above mentioned shortcomings of the existing lift axle control system.
OBJECTS OF THE INVENTION
[0010] An object of the present subject matter is to provide a lift axle control system for lifting or lowering a lift axle as per the load of the vehicle.
[0011] Another object of the present subject matter is to reduce consumption of compressed air required for lifting or lowering of the lift axle.
[0012] Another object of the present subject matter is to reduce excess air consumption due to continuous up & down movement of ALSV lever causing frequent exhaust from ALSV.
[0013] Another object of the present subject matter is to reduce excess air consumption due to braking system of the lift axle when the said axle is in lift position.
[0014] Yet another object of the present subject matter is to reduce air consumption during the lifting and deploying of the lift axle.
[0015] Another object of the present subject matter is to supply air of the lift bellows to the suspension bellows whenever air of the lift bellows is to be exhausted.
[0016] Yet another object of the present subject matter is to reduce the air wastage thereby increasing the engine efficiency by reducing the fuel consumption.

SUMMARY
[0017] Before the present system is described, it is to be understood that this application is not limited to the particular machine or device, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a lift axle control system, and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
[0018] The present subject matter describes a lift axle control system for a vehicle. The lift axle control system comprises at least one air flow controlling device configured to supply controlled supply of air to the various devices of the lift axle control system for deploying and lifting of said lift axle respectively based on air supply. A control unit is configured for controlling said at least one air flow controlling device. A sensor is connected to the control unit configured for sensing ride height of the vehicle. At least one braking system controlling valve is configured for conditional braking of said lift axle A plurality of sensor are provided for sensing pressure at various locations of said system and are configured to be connected to the control unit. The various devices of the lift axle control system for deploying and lifting of said lift axle based on air supply are at least one suspension bellows and at least one lift bellows respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and device disclosed in the document and the drawings. The detailed description is described with reference to the following accompanying figures.
[0020] Figure 1 illustrates a view of a lift axle of a vehicle, in accordance with an embodiment of the present subject matter.
[0021] Figure 2 illustrates a schematic of an existing lift axle control system.
[0022] Figure 3 illustrates a schematic of a current lift axle control system, in accordance with an embodiment of the present subject matter.
[0023] Figure 4 illustrates a schematic of the current lift axle control system, in accordance with another embodiment of the present subject matter.
[0024] Figure 5 illustrates a schematic of the current lift axle control system, in accordance with yet another embodiment of the present subject matter.
[0025] Figure 6 illustrates a flow chart of the current lift axle control system, in accordance with an embodiment of the present subject matter.
[0026] The figure depicts various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures illustrated herein may be employed without departing from the principles of the disclosure described herein.
REFERRAL NUMERALS:

Element Description Reference Numeral
Lift axle 2
Axle beam 4
Linkages 6
Chassis frame 8
Air Tank (Reservoir) 10
Inlet Solenoid valve 11
5/2 Solenoid valve 12
Suspension (main) Bellows 13
Lift Bellows 14
height sensor 15
control unit (ECU) 16
Brake Solenoid valve 17
Main pressure sensor 20
Lift pressure sensor 21
Override switch 22
Revere gear switch 23
Non return valve 24
Relay Valve 25
2/2 Solenoid valve 26

DETAILED DESCRIPTION
[0027] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, 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 any devices and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, devices and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0028] 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. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0029] The existing lift axle control system controls the lift axle based on the inputs from ALSV/LDV lever which is connected to drive axle. Due to road irregularities, the ALSV lever keeps on moving in up & down direction. This causes the fluctuations of the pressure at supply port of LACV, however this doesn’t cause immediate change in position of the lift axle as there is time delay feature of LACV. However due to continuous up & down movement of ALSV lever, there is frequent exhaust from ALSV, which causes excess air consumption. Whenever there is change in axle position (lifted or deployed), air from either the lift bellows or the suspension bellows is exhausted to the atmosphere. All the above condition causes excess consumption of compressed air. Which in turn cause higher duty cycle of the air compressor & poor fuel economy of the vehicle.
[0030] The present subject matter describes a lift axle control system for a vehicle. The lift axle control system comprises a control unit, a height sensor, an inlet solenoid valve, a 5/2 solenoid valve, a main pressure sensor and a lift pressure sensor. The height sensor may be connected to the control unit and the height sensor indicates loading state of the vehicle by sensing ride height of the vehicle. The inlet solenoid valve comprises of an air supply port and an air delivery port. The air supply port may be configured to receive an air supply from an air tank upon receiving input from the control unit. The 5/2 solenoid valve may adjust an air volume of at least a suspension bellows and a lift bellows based on a signal from the control unit. The 5/2 solenoid valve comprises a supply port connected to the air delivery port of the inlet solenoid valve, a first delivery port connected to the suspension bellows and a second delivery port connected to the lift bellows. The main pressure sensor of the suspension bellows is connected to the control unit. The lift pressure sensor of the lift bellows is connected to the control unit. The lift axle control system may comprise a non-return valve between the left bellows and the suspension bellows to allow passage of air form the lift bellows to the suspension bellows. To control the opening of the non-return valve a relay valve or a solenoid valve may be used based on the required conditions. In this way the lift axle control system utilizes the air of the lift bellows to be supplied to the suspension bellows whenever the air of lift bellows to be exhausted. Therefore the lift axle control system reduces consumption of the compressed air required for lifting or lowering of the lift axle.
[0031] The lift axle control system further comprises a brake solenoid valve to activate the brake system of the lift axle only in a condition when the lift axle is deployed.
[0032] As shown in figure 1, a lift axle 2 with wheels attached is fitted on a chassis frame 8 of the vehicle through an axle beam 4. The axle beam 4 has an arrangement of a lift bellows 14 which lifts the lift axle 2, when inflated. The lift bellows are further supported by a plurality of linkages 6. The lift axle 2 is further connected to the chassis frame 8 with a main bellows 13, also known as suspension bellows. When the lift axle 2 is deployed, the air is depleted form the lift bellows 14 & the suspension bellows 13 are inflated. To lift the lift axle 2, air from the suspension bellows 13 is depleted & the lift bellows 14 are inflated.
[0033] Now referring to figure 3, a schematic of the lift axle control system 1 is shown according to an embodiment of the present subject matter. The lift axle control system 1 comprises of a control unit 16 and a height/level sensor 15. The height sensor 15 may be fitted on the chassis frame 8 of the vehicle. In a preferred embodiment the height sensor 15 is an electronic type height or level sensor. An output signal of the height sensor 15 may be received by the control unit 16. The lift axle control system 1 further comprises of an inlet solenoid valve 11 and a 5/2 solenoid valve 12. The control unit 16 is electrically connected to the inlet solenoid valve 11 and the 5/2 solenoid valve 12 and controls the actuation of all these valves. An air tank or reservoir 10 is supplied with compressed air supply from air compressor mounted on the engine. The inlet solenoid valve 11 comprises an air supply port and an air delivery port. The air supply port of the inlet solenoid valve (11) is connected to the air tank 10 and an air delivery port of the inlet solenoid valve 11 is connected to a supply port of the 5/2 solenoid valve 12. The 5/2 solenoid valve 12 further comprises two delivery ports, out of which a first delivery port is connected to the main or suspension bellows 13 and a second delivery port is connected to the lift bellows 14. The lift axle control system 1 comprises of a main pressure sensor 20 connected to the suspension bellows 13 to sense air pressure in suspension bellows 13. The lift axle control system 1 comprises a lift pressure sensor 21 connected to the lift bellows 14 to sense air pressure in lift bellows 14. The output signals from the main pressure sensor 20 and the lift pressure sensor 21 are sent to the control unit 16.
[0034] When the vehicle ignition is switched ON, the 5/2 solenoid valve 12 is switched ON by receiving command from the control unit 16. In ON condition of the 5/2 solenoid valve 12, the pressure in the suspension bellows 13 is exhausted to atmosphere. In this condition, the inlet solenoid valve 11 is switched on so that air form the air tank 10 is supplied to the lift bellows 14 through the second delivery port of the 5/2 solenoid valve. Once the pressure of the lift bellows 14 is reached to a specified value, the inlet solenoid valve 11 is switched off and the lift axle 2 will be lifted.
[0035] During travel of the vehicle, the change in ride height of the chassis 8 due to loading or unloading in vehicle is sensed by the height sensor 15 and the output is sent to the control unit 16. Accordingly the control unit 16 actuates the inlet solenoid valve 11 and the 5/2 solenoid valve 12 to deploy or lift the lift axle 2 based on output of the height sensor 15. The control unit (16) is programmed with decision matrix of the height sensor output v/s bellows pressure values, as given in below table 1.
Height sensor output (V) Inlet solenoid actuation state 5/2 Solenoid
actuation state Suspension bellows pressure sensor output Lift bellow pressure sensor output Axle position Brake solenoid valve
V < X On/ Off ON 0 unit 8 unit Lifted OFF

V = X
On/ Off
OFF As per height sensor output value
0 Unit Deployed ON
Table 1
[0036] When the vehicle is loaded, the height sensor output increases. If it is equal or more than a certain value X (laden condition value), then the 5/2 solenoid valve 12 is switched OFF. In OFF condition of the 5/2 solenoid valve 12, the pressure of the lift bellows 14 is exhausted to atmosphere and the inlet solenoid valve 11 is connected to the suspension bellows 13 through the first delivery port of the 5/2 solenoid valve. In this condition, the inlet solenoid valve 11 is also switched on by electronic control unit 16, so that air from the air tank 10 is supplied to the suspension bellows 13 to inflate the suspension bellows 13. Thus, the lift axle 2 will be deployed.
[0037] In an embodiment of the present invention, the main pressure sensor 20 may monitor the pressure in the suspension bellows 13 and fed the pressure data continuously to the control unit 16. Once the pressure in the suspension bellows 13 is reached to a specified value, the inlet solenoid valve 11 is switched off and the lift axle 2 remains in deployed condition. Now, the lift axle 2 is supported by the suspension bellows 13 whose pressure is maintained as per the output of the height sensor 15. The control unit 16 maintains a specific air pressure into the suspension bellows 13 based on the decision matrix of the height sensor output v/s bellows pressure values, as given in below table 2.
Sr No Height sensor output (V) Suspension bellows pressure Lift bellow pressure
1 X1 > V 0 unit 8 Unit
2 X2> V > X1 2.5 Unit 0 Unit
3 X3> V > X2 3.0 Unit 0 Unit
4 X4> V > X3 3.5 Unit 0 Unit
5 X5> V > X4 4.0 Unit 0 Unit
6 X6> V > X5 4.5 Unit 0 Unit
7 X7> V > X6 5.0 Unit 0 Unit
8 X > V > X7 5.5 Unit 0 Unit
Table 2
[0038] Further in an embodiment of the present subject matter, the lift axle control system 1 comprises a brake solenoid valve 17. The brake solenoid valve 17 is fitted in a brake line of the lift axle 2 before a brake chamber and connects the delivery of ABS modulator valve to the brake chamber of the lift axle 2. Since there is a pressure signal from the main pressure sensor 20 to the control unit 16, the control unit 16 understands that the axle is deployed and actuates (switch ON) the brake solenoid valve 17. Once the brake solenoid valve 17 is in switched ON condition, air pressure is supplied to the brake chambers and the brakes are applied. If the brake solenoid valve 17 is in OFF condition, the air cannot be supplied to brake chamber from the ABS modulator valve. This feature is to ensure that the brakes are applied only when the lift axle is in deployed condition. If the axle is in lifted position, the brakes on the lift axle are not applied as it is redundant to apply the brakes on the lifted axle. This ensure the effective use of compressed air and results in reduced air consumption.
[0039] Another arrangement can be made to put the ABS solenoid valve of lift axle into the hold mode by providing the signal pressure signal to ABS ECU so that the brakes are not applied on the lift axle if the lift axle is in lifted condition. When vehicle is unloaded, height sensor 15 output is reduced lower than certain value (Unladen condition value), then the 5/2 solenoid valve 12 is swathe ON. In “ON” condition of 5/2 solenoid valve 12, the main bellow pressure 13 is exhausted to atmosphere and inlet solenoid valve 11 delivery is connected to the lift bellows 14. In this condition, inlet solenoid valve 11 is switched on so that air tank 10 pressure is supplied to the lift bellow 14. Once the lift bellow 14 pressure is reached to tank pressure value or specified value, the inlet solenoid valve 11 is switched off and the lift axle will be lifted.
[0040] Further in an embodiment of the present subject matter, the lift axle control system 1 comprises an override switch 22 & a reverse gear switch 23. If there is ON signal from either of the switches, the override switch 22 or the reverse gear switch 23, which are electrically connected to the control unit 16, which will switch on the 5/2 solenoid valve 12. In the event of lifting or lowering of the lift axle 2, the 5/2 solenoid valve 12 is actuated first and then the inlet solenoid valve 11 is actuated. It means air pressure of the suspension bellows 13 will be exhausted first then the lift bellows 14 will be inflated and the lift axle 2 will be lifted.
[0041] In the ignition OFF condition of the vehicle, the 5/2 solenoid valve is switched OFF. The air pressure of the lift bellows 14 is exhausted to atmosphere and the suspension bellows 13 is inflated with air pressure up to a certain specified value and the lift axle is deployed. This feature is to avoid theft of the wheels of the lift axle 2 in parked condition of the vehicle.
[0042] Now referring to figure 4, a schematic of the lift axle control system 1 is shown according to an alternate embodiment of the present subject matter. A non-return valve 24 and a relay valve 25 is added between the lift bellows 14 and the suspension bellows 13. A supply port of the relay valve 25 is connected to the lift bellows 14 and a delivery port of the relay valve 25 is connected to the suspension bellows 13 through the non-return valve 24 such that the air can flow from the lift bellows 14 to the suspension bellows 13. A signal port of the relay valve 25 is connected to the first delivery port of the 5/2 solenoid valve 12. The signal port of the relay valve 25 receives signal from the 5/2 solenoid valve 12 to supply air through the non-return valve 24. Whenever the vehicle is loaded, the height sensor 15 output increases. If the output of the height sensor 15 is more than a specific value, then the 5/2 solenoid valve 12 is switched to OFF condition. In OFF condition of the 5/2 solenoid valve 12, the first delivery port of 5/2 solenoid valve is connected to the suspension bellows 13 and at the same time the lift bellows 14 is connected to the suspension bellows 13 through the relay valve 25 and the non-return valve 24 . The air from the lift bellows 14 is exhausted and supplied to the suspension bellows 13 through the non-return valve 24. As at the same time, the inlet solenoid valve 11 is also switched ON, the air from the air tank 10 is also supplied to the suspension bellows 13. Thus, the lift axle 2 will be deployed. This arrangement will ensure recirculation of air from the lift bellows 14 into the suspension bellows 13 and thus reduces air consumption.
[0043] Now referring to figure 5, a schematic of the lift axle control system 1 is shown according to one more embodiment of the present subject matter. A non-return valve 24 and a 2/2 solenoid valve 26 is added between the lift bellows 14 and the suspension bellows 13. A supply port of the 2/2 solenoid valve 26 is connected to the lift bellows 14 and a delivery port of the 2/2 solenoid valve 26 is connected to the suspension bellows 13 through the non-return valve 24 such that the air can flow from the lift bellows 14 to the suspension bellows 13. A signal port of the 2/2 solenoid valve 26 is electrically connected to the control unit 16. Whenever the vehicle is loaded, the height sensor 15 output increases. If the output of the height sensor 15 is more than a specific value, then the 5/2 solenoid valve 12 is switched to OFF condition. In OFF condition of the 5/2 solenoid valve 12, the first delivery port of 5/2 solenoid valve is connected to the suspension bellows 13 and at the same time the lift bellows 14 is connected to the suspension bellows 13 through the 2/2 solenoid valve 25 and the non-return valve 24 . Based on the command from the control unit 16 the 2/2 solenoid valve 26 allows the air from the lift bellows 14 to be exhausted and supplied to the suspension bellows 13 through the non-return valve 24. As at the same time, the inlet solenoid valve 11 is also switched ON, air from the air tank 10 is also supplied to the suspension bellows 13. Thus, the lift axle 2 will be deployed. This arrangement will ensure recirculation of air from the lift bellows 14 into the suspension bellows 13 and thus reduces air consumption.
[0044] Now referring to figure 6, a flow chart of the various signals received, processed and sent by the control unit 16 are illustrated. The control unit 16 receives signal of the ignition switch. If the ignition switch is OFF, the control unit 16 is configured to switch off the 5/2 solenoid valve 12 and the lift axle 2 is deployed. If the ignition switch is ON, the control unit 16 further takes input from the height sensor 15. If the height sensor output V is less than a predetermined value X, the control unit 16 further commands to switch ON the 5/2 solenoid valve 12 and results in lifting of the lift axle 2. If the height sensor output V is more than X, the control unit commands to switch off the 5/2 solenoid valve 12 and also switches on the inlet solenoid valve 11. From the inlet solenoid valve 11 air pressure is supplied to the suspension bellows 13 up to a specific pressure value as detected by the main pressure sensor 20. If the pressure in the suspension bellows 13 has reached the specific value, the inlet solenoid valve 11 is switched off by the control unit 16 and the lift axle 2 is deployed.
[0045] Accordingly the present subject matter discloses a lift axle control system 1 for a vehicle. The lift axle control system 1 comprises at least one air flow controlling device configured to supply controlled supply of air to the various devices of the lift axle control system for deploying and lifting of said lift axle respectively based on air supply. A control unit 16 is configured for controlling said at least one air flow controlling device. A sensor 15 is connected to the control unit 16 configured for sensing ride height of the vehicle. At least one braking system controlling valve 17 is configured for conditional braking of said lift axle A plurality of sensor (20, 21) are provided for sensing pressure at various locations of said system and are configured to be connected to the control unit 16. The various devices of the lift axle control system for deploying and lifting of said lift axle 2 based on air supply are at least one suspension bellows 13 and at least one lift bellows 14 respectively.
[0046] The sensor 15 is connected to the control unit 16 and is configured for sensing ride height of the vehicle such that an output of the sensor 15 indicates loading state of the vehicle. The sensor 15 may be fitted to the chassis frame 8 of the vehicle.
[0047] In an embodiment, the at least one air flow controlling device configured to supply controlled supply of air is an inlet solenoid valve 11. The inlet solenoid valve 11 comprises of an air supply port and an air delivery port such that the air supply port is configured to receive an air supply from an air tank 10 upon receiving input from the control unit 16.
[0048] In an embodiment, the at least one air flow controlling device configured to supply controlled supply of air is a solenoid valve 12 for adjusting an air volume of said suspension bellows 13 and a lift bellows 14 based on a signal from the control unit 16. The 5/2 solenoid valve 12 constitutes a supply port connected to the air delivery port of the inlet solenoid valve 11, a first delivery port connected to the suspension bellows 13 and a second delivery port connected to the lift bellows 14.
[0049] The pressure sensor 20 is configured for sensing air pressure of suspension bellow 13 and the pressure sensor 21 is configured for sensing air pressure of the lift bellows 14.
[0050] The lift axle 2 is configured to be lifted by exhausting air pressure of the suspension bellows 13 and increasing air pressure of the lift bellows 14 on switching ‘ON’ of the ignition switch and height sensor output ‘V’ is constituted to be less than a predetermined value.
[0051] The lift axle 2 is configured to be deployed by exhausting air pressure of the lift bellows 14 and increasing air pressure of the suspension bellows 13 on switching ‘ON’ of the ignition switch and height sensor output ‘V’ is constituted to be less than a predetermined value.
[0052] The said at least one braking system controlling valve 17 is configured for actuation of braking circuit of said lift axle in deployed position of said lift axle and to restrain the braking circuit of said lift axle in lifted position. In an embodiment, the at least one braking system controlling valve 17 is a brake solenoid valve 17 configured to be fitted in a brake line of the lift axle 2 and is connected to the control unit 16.
[0053] Further the lift axle control system 1 is provided with a reverse gear switch 23 configured to lift the lift axle 2 whenever the vehicle is engaged in a reverse gear.
[0054] Furthermore the lift axle control system 1 is configured with an override to lift the lift axle 2 on actuation of said override switch 22 by overriding any of the conditions of the said lift axle control system 1.
[0055] In an another embodiment, the lift axle control system 1 is configured with at least one non-return valve 24 and at least one control valve to allow passage of air from the lift bellows 14 to the suspension bellows 13.The control valve may be a relay valve 25 or a solenoid valve 26.
[0056] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include the following.
[0057] Some embodiments of the subject matter enable lowering and lifting of a lift axle as per the load of the vehicle.
[0058] Some embodiments of the subject matter enable reduction in usage of compressed air required for lifting or lowering of the lift axle.
[0059] Some embodiments of the subject matter enable supply of air from the lift bellows to the suspension bellows whenever air of the lift bellows is to be exhausted.
[0060] Although implementations for the lift axle control system 1 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 described. Rather, the specific features are disclosed as examples of implementation for the lift axle control system 1.
,CLAIMS:
1. A lift axle control system (1) for a vehicle, wherein the lift axle control system (1) comprising:
at least one air flow controlling device configured to supply controlled supply of air to the various devices of the lift axle control system for deploying and lifting of a lift axle respectively based on air supply;
a control unit (16) for controlling said at least one air flow controlling device; a sensor (15) connected to the control unit (16) configured for sensing ride height of the vehicle;
at least one braking system controlling valve (17) configured for conditional braking of said lift axle; and
plurality of sensor (20,21) for sensing pressure at various locations of said system are configured to be connected to the control unit (16).

2. The lift axle control system (1) as claimed in claim 1, wherein said various devices of the lift axle control system for deploying and lifting of said lift axle respectively based on air supply are at least one suspension bellows (13) and at least one lift bellows (14).

3. The lift axle control system (1) as claimed in claim 1, wherein said sensor (15) connected to the control unit (16) configured for sensing ride height of the vehicle, wherein an output of the sensor (15) indicates loading state of the vehicle.

4. The lift axle control system (1) as claimed in claim 1, wherein said at least one air flow controlling device configured to supply controlled supply of air is an inlet solenoid valve (11) comprising of an air supply port and an air delivery port wherein the air supply port is configured to receive an air supply from an air tank (10) upon receiving input from the control unit (16).

5. The lift axle control system (1) as claimed in claim 1, wherein said at least one air flow controlling device configured to supply controlled supply of air is a solenoid valve (12) for adjusting an air volume of said suspension bellows (13) and a lift bellows (14) based on a signal from the control unit (16), wherein the 5/2 solenoid valve (12) constitutes a supply port connected to the air delivery port of the inlet solenoid valve (11), a first delivery port connected to the suspension bellows (13) and a second delivery port connected to the lift bellows (14).

6. The lift axle control system (1) as claimed in claim 1, wherein said pressure sensor (20) is configured for sensing air pressure of suspension bellow (13) and said pressure sensor (21) is configured for sensing air pressure of the lift bellows (14).

7. The lift axle control system (1) as claimed in claim 1, wherein the lift axle (2) is configured to be lifted by exhausting air pressure of the suspension bellows (13) and increasing air pressure of the lift bellows (14) on switching ‘ON’ of the ignition switch and height sensor output ‘V’ is constituted to be less than a predetermined value.

8. The lift axle control system (1) as claimed in claim 1, wherein the lift axle (2) is configured to be deployed by exhausting air pressure of the lift bellows (14) and increasing air pressure of the suspension bellows (13) on switching ‘ON’ of the ignition switch and height sensor output ‘V’ is constituted to be less than a predetermined value.

9. The lift axle control system (1) as claimed in claim 1, wherein said at least one braking system controlling valve (17) is configured for actuation of braking circuit of said lift axle in deployed position of said lift axle and to restrain the braking circuit of said lift axle in lifted position.

10. The lift axle control system (1) as claimed in claim 1, wherein said at least one braking system controlling valve (17) is a brake solenoid valve (17) configured to be fitted in a brake line of the lift axle (2) and is connected to the control unit (16).

11. The lift axle control system (1) as claimed in claim 1, wherein the lift axle control system (1) is provided with a reverse gear switch (23) configured to lift the lift axle (2) whenever the vehicle is engaged in a reverse gear.

12. The lift axle control system (1) as claimed in claim 1, wherein the lift axle control system (1) is configured with an override to lift the lift axle (2) on actuation of said override switch (22) by overriding any of the conditions of the said lift axle control system (1).

13. The lift axle control system (1) as claimed in claim 1, wherein the lift axle control system (1) is configured with at least one non-return valve (24) and at least one control valve to allow passage of air from the lift bellows (14) to the suspension bellows (13).

14. The lift axle control system (1) as claimed in claim 13, wherein said at least one control valve is a relay valve (25).

15. The lift axle control system (1) as claimed in claim 13, wherein said at least one control valve is a solenoid valve (26).

16. The lift axle control system (1) as claimed in claim 1, wherein the height sensor (15) is fitted to the chassis frame (8) of the vehicle.