Description:Field of the invention
[0001] The present invention relates to a lift axle system. More specifically, the present invention relates to a system and method for automatic control of lift axle in a vehicle.

Background of the invention
[0002] In multi-axle trailers equipped with air suspension systems, the ability to selectively lift or lower one or more axles plays a critical role in maintaining proper load distribution, reducing tire wear, and improving vehicle manoeuvrability. Conventional systems fall into one of two categories one with fully manual configurations and with fully electronic, sensor-based systems. Each of these present’s limitations in terms of usability, reliability, and practical implementation, particularly in cost-sensitive and infrastructure-limited transport markets.
[0003] Manually operated axle lifts systems rely on the driver to activate or deactivate lift functions via dashboard switches or cabin-mounted controls. These systems often employ solenoid-operated directional control valves to direct air into suspension or lift bellows. The operation depends heavily on driver awareness and discipline. If the axle remains lifted during a fully loaded condition either by negligence or oversight the remaining axles are forced to carry excess load, potentially leading to air bellow failure, tire degradation, or compromised braking and steering performance.
[0004] On the other end, electronically controlled systems use sensors and ECUs (Electronic Control Units) to detect parameters such as vehicle load, road conditions, or vehicle speed, and adjust axle configurations accordingly. While these systems offer advanced functionality, they come with significant drawbacks. They require full integration with the trailer’s braking and pneumatic systems often through an Electronic Braking System (EBS). This necessitates a comprehensive changeover from conventional trailer hardware, which is not only expensive but also requires specialized installation and servicing expertise. Moreover, electronic components, particularly sensors and wiring harnesses, are prone to degradation in dusty, wet, or high-vibration environments, limiting long-term reliability in real-world operations.
[0005] Therefore, there is a need for a system and method for automatic control of lift axle in a vehicle which overcomes one or more drawbacks of the above-mentioned prior arts.

Objects of the invention
[0006] An object of the present invention is to provide a system and method for automatic control of lift axle in a vehicle.
[0007] Another object of the present invention is to provide a system and method for automatic control of lift axle in a vehicle thereby eliminating the need for manual driver intervention.
[0008] Yet another object of the present invention is to provide a system and method for automatic control of lift axle in a vehicle that enables seamless integration with existing pneumatic suspension systems, without requiring significant modification to the vehicle architecture.
[0009] Another one object of the present invention is to provide a system and method for automatic control of lift axle in a vehicle that includes a pneumatic control valve that operates without electrical components such that the lifting of the lift axle in unloaded condition and lowering of the lift axle in loaded condition is purely pneumatic and is controlled by the pilot principle of ILAS-PC Valve.
[0010] One more object of present invention is to provide a system and method for automatic control of lift axle in a vehicle that minimizes tire wear and air bellow damage by ensuring that the lift axle is lifted only during unloaded or light-load conditions.
[0011] Still another object of the present invention is to provide a system and method for automatic control of lift axle in a vehicle that ensures cost-effective automation of lift axle functionality, thereby addressing the needs of commercial vehicle operators in emerging markets.

[0012] Yet another object of the present invention is to provide a system and method for automatic control of lift axle in a vehicle with priority-based control logic, which ensures that manual, automatic, and signal-based commands can be managed in a coordinated manner.

Summary of the invention
[0013] According to the present invention, a system for automatic and manual control of lift axle in a vehicle is provided. The system includes an air reservoir, a pressure protection valve, a EGP levelling valve, a pilot-operated pneumatic directional control valve, a solenoid-actuated directional control valve and a control module.
[0014] The air reservoir is configured to supply compressed air in to the system. The pressure protection valve is connected to the air reservoir and is configured to permit air flow only when a threshold pressure is reached. The EGP levelling valve is mechanically coupled to a chassis or a suspension member of the vehicle and is configured to detect a load condition of the vehicle and to output a pilot pressure in response to the load condition. The pilot-operated pneumatic directional control valve (ILAS-PC) is in fluid communication with the EGP levelling valve and is configured to automatically route compressed air to inflate or deflate a plurality of suspension bellows and lift bellows based on the pilot pressure based on the load condition of the vehicle, thereby controlling the lifting and lowering of the lift axle without electrical input.
[0015] The solenoid-actuated directional control valve (ILAS-EC) is configured to temporarily route compressed air to the lift bellows for a predetermined duration in response to an electrical input signal from the vehicle. The control module is electrically connected to the solenoid-actuated directional control valve (ILAS-EC) and is configured to receive the electrical signals including at least one of a reverse gear signal and a turn signal. The control module also triggers the solenoid-actuated directional control valve (ILAS-EC) for the predetermined duration through a timer module. During normal operating conditions, the ILAS-PC valve maintains the automatic control based on the load condition of the vehicle and during reversing or turning, the control module activates the solenoid-actuated directional control valve to temporarily lift the lift axle.
[0016] In an aspect of the invention, the control module is configured to prevent the actuation of the solenoid-actuated directional control valve (ILAS-EC) when the EGP levelling valve detects a heavy load condition above a threshold pressure.
[0017] In an aspect of the invention, the pilot-operated pneumatic directional control valve (ILAS-EC) includes an inlet port connected to the air reservoir, a suspension bellows outlet port, a lift bellows inlet port, a lift bellows outlet port, an exhaust port and a pilot port.
[0018] In an aspect of the invention, the pilot port is configured to receive the pilot pressure from the EGP levelling valve to automatically shift an internal spool and to control the air routing between the respective ports based on load condition thereby inflating or deflating the suspension bellows and lift bellows without requiring electrical input.
[0019] In an aspect of the invention the pilot-operated pneumatic directional control valve (ILAS-EC) includes a spool-spring mechanism configured to shift positions in response to pilot pressure at the pilot port to direct airflow between the inlet port connected to the air reservoir and the suspension bellows outlet port or between the lift bellows inlet port and the lift bellows outlet port.
[0020] In an aspect of the invention, when the EGP levelling valve outputs a pilot pressure greater than 3.5 bar, the internal spool shifts to allow airflow from the inlet port connected to the air reservoir to the suspension bellows outlet port inflating a plurality of suspension bellows and deflating a plurality of lift bellows through lift bellow output port to the exhaust port.
[0021] In an aspect of the invention, when the EGP levelling valve outputs a pilot pressure less than 3.5 bar, the internal spool shifts to allow airflow from lift bellows inlet port to the lift bellows outlet port inflating the plurality of lift bellows and deflating the plurality of suspension bellows through suspension bellow outlet port to the exhaust port.
[0022] In an aspect of the invention, the pressure protection valve is configured to block air flow to the system when pressure in the air reservoir is below 5-6 bar.
[0023] In an aspect of the invention, the solenoid-actuated directional control valve (ILAS-EC) is configured to inflate the plurality of lift bellows for a preset duration between 90 and 120 seconds as controlled by the electronic timer module.
[0024] In an aspect of the invention, the control module is mounted within the vehicle cabin and includes a relay circuit having input terminals corresponding to vehicle connectors for receiving electrical signals from the reverse signal, the turn signal indicator, and the manual override switch.
[0025] In an aspect of the invention, the air discharged from the exhaust port of the pilot-operated pneumatic directional control valve (ILAS-EC) and the solenoid-actuated directional control valve (ILAS-EC) is directed through a check valve and is configured to permit reverse air flow when a pressure differential of 0.4 bar is present across the check valve.
[0026] In an aspect of the invention, the EGP levelling valve is configured to detect vertical displacement of the chassis of the vehicle to determine the load condition.
[0027] In an aspect of the invention, a method for automatic control of lift axles in a vehicle is provided. The method begins by supplying compressed air from an air reservoir through a pressure protection valve to the pneumatic suspension system, wherein the pressure protection valve ensures that air flow is enabled only once a minimum threshold pressure is achieved. Following this, a load condition of the vehicle is detected using a EGP levelling valve mechanically coupled to the suspension of the vehicle. The EGP levelling valve is configured to output a pilot pressure that reflects the vertical displacement of the suspension, which in turn represents the current load condition of the vehicle. This pilot pressure is then directed to a pilot port of a pilot-operated pneumatic directional control valve (ILAS-PC).
[0028] In response to the received pilot pressure, an internal spool of the ILAS-PC valve is actuated to control the routing of compressed air through various ports: specifically, from inlet port to suspension bellows outlet port, and from lift bellows inlet port to lift bellows outlet port. When the pilot pressure corresponds to a heavy-load condition, the ILAS-PC valve directs the compressed air to inflate a plurality of suspension bellows while simultaneously venting a plurality of lift bellows, thereby lowering the lift axle for load-bearing and stability. Alternatively, when the pilot pressure indicates a light-load condition, the ILAS-PC valve inflates the lift bellows and vents the suspension bellows, thus lifting the axle to avoid unnecessary ground contact and reduce tire wear. In addition to the load-based pneumatic control, the method includes receiving an electrical signal by a control module, wherein the signal corresponds to at least one of a reverse gear engagement or a turn signal activation by the driver. Upon receiving this electrical input, the control module activates a solenoid-actuated directional control valve (ILAS-EC) through an electronic timer module. The ILAS-EC valve then inflates the lift bellows for a preset duration, typically between 90 to 120 seconds, to temporarily raise the lift axle and during reversing or turning. After the preset duration expires, the solenoid-actuated directional control valve is deactivated by the control module. Importantly, during a detected heavy-load condition, the control module overrides the electrical input and prevents the activation of the solenoid-actuated valve, ensuring that the lift bellows remain vented and the lift axle stays lowered to maintain vehicle stability and safety under load.

Brief Description of drawings
[0029] The advantages and features of the present invention will be understood better with reference to the following detailed description and claims taken in conjunction with the accompanying drawings, wherein like elements are identified with like symbols, and in which:
[0030] Figure 1 illustrates a schematic representation for a system for the automatic control of lift axles in a vehicle in accordance with the present invention;
[0031] Figure 2 illustrates a line diagram of a system for the automatic control of lift axles in a vehicle with pilot-operated pneumatic directional control valve (ILAS-PC) in accordance with the present invention;
[0032] Figure 3a and Figure 3b illustrates a cross-sectional view of the operation of the pilot-operated pneumatic directional control valve (ILAS-PC) under high pressure and low-pressure condition respectively for a system for the automatic control of lift axles in a vehicle with pilot-operated pneumatic directional control valve (ILAS-PC) in accordance with the present invention;
[0033] Figure 4 illustrates an embodiment of the invention showing the system (100) implemented on a tandem axle trailer configuration, in which both the lift axles (20) are equipped with automatic lift and drop capability using ILAS-PC valve (30);
[0034] Figure 5 illustrates another embodiment of the invention where the ILAS-PC valve (30) is applied to a tri-axle trailer configuration; and
[0035] Figure 6 illustrates a method for the automatic control of lift axles in a vehicle in accordance with the present invention.

Detailed description of the invention
[0036] An embodiment of this invention, illustrating its features, will now be described in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.
[0037] The present invention relates to a lift axle system. More specifically, the present invention relates to a system and method for the automatic control of lift axles in a vehicle, particularly heavy-duty trailers equipped with air suspension systems. The invention is configured to provide load-based actuation of lift axles using a pilot-operated pneumatic directional control valve (ILAS-PC) and to during reversing or turning operations actuation of lift axles using solenoid-actuated directional control valve (ILAS-EC) governed by electronic signals. The system eliminates the need for manual intervention, improves load distribution, reduces tire wear, improves fuel efficiency, and ensures safer vehicle handling during both loaded and unloaded conditions. Additionally, the system is designed to integrate seamlessly with existing pneumatic configurations, providing an automated and cost-effective solution without requiring complex electronic control units (ECUs) or complete system overhauls.
[0038] The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.
[0039] The disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms.
[0040] Referring now to Figures 1, 2, 3 4, and 5 a system (100) for automatic control of lift axle (20) in a vehicle according to the present invention is provided. The system (100) includes an air reservoir (10), a pressure protection valve (15), a EGP levelling valve (25), a pilot-operated pneumatic directional control valve (30), a solenoid-actuated directional control valve (40), a plurality of lift bellows (45), a plurality of suspension bellows (44) and a control module (50). During operation, the system (100) is capable of functioning in different modes depending on the load condition of the vehicle and the driving actions taken by the operator. The different modes of operation include automatic load-based mode and reversing or turning mode.
[0041] Referring again to figure 1 and figure 2, the air reservoir (15) is configured to supply compressed air to the system (100). Specifically, the air reservoir (10) stores and supplies air to the pneumatic system (100), powering components such as the plurality of lift bellows (45) and the plurality of suspension bellows (44). The pressure protection valve (15) is connected to the air reservoir (10) and is configured to permit air flow only when a threshold pressure is reached. In an embodiment the pressure protection valve (15) is a spring-loaded check valve or a pressure-sensitive valve. In the present invention the threshold pressure for the pressure protection valve (15) is set between 5 – 6 bar. More specifically the pressure protection valve (15) blocks the air flow to the system (100) when pressure in the air reservoir (10) is below 5- 6 bar.
[0042] Further the system (100) includes a EGP (Exhaust governed pressure) levelling valve (25), mechanically linked to a chassis or a suspension member (not shown in figure) of the vehicle as shown in Figure 1 and Figure 2. The EGP levelling valve (25) is configured to detect a load condition of the vehicle. The EGP levelling valve (25) detects the vertical displacement of the chassis of the vehicle to determine the load condition. The load condition refers to the weight or load carried by the vehicle, which directly affects the vertical displacement of the vehicle's chassis. Specifically, when the vehicle is lightly loaded, the EGP levelling valve (25) activates the system (100) to raise the lift axle (20) and when heavily loaded, the EGP levelling valve (25) activates the system (100) to lower the lift axle (20). Further the EGP levelling valve (25) sends pilot air pressure to the pilot-operated pneumatic directional control valve (30) to raise or lower the lift axle (20) based on the determined load condition.
[0043] Referring again to figure 1, during the automatic load-based mode, the system (100) operates without any input from the driver. For example, when the vehicle is empty, the EGP levelling valve (25) detects the raising position of the chassis indicating the light load condition. In response, the EGP levelling valve (25) sends pilot pressure to the pilot-operated pneumatic directional control valve (30). The pilot-operated pneumatic directional control valve (30) from herein onwards referred as ILAS-PC valve (30) which is Integrated Laden Axle Sensing-Pneumatic Control valve. Specifically, the ILAS-PC valve (30) is in fluid communication with the EGP levelling valve (25) and controls the lifting and lowering of the lift axle (20) based on the load condition detected by the EGP levelling valve (25). The pilot pressure from the ILAS-PC valve (30) then activates the plurality of lift bellows (44) by inflating them and raising the lift axle (20). Simultaneously, the suspension bellows (45) are vented, as they are not required for this light-load state. The plurality of lift bellows (44) is operably connected to the lift axle (20) of the vehicle and the plurality of suspension bellows (45) is operably connected to the suspension of the vehicle. Specifically, during operation, when the EGP levelling valve (25) detects that the vehicle is operating under a light-load condition, the ILAS-PC valve (30) then directs the compressed air from the air reservoir (10) to the plurality of lift bellows (44) to inflate the lift bellows (44) and simultaneously vent the plurality of suspension bellows (45).
[0044] Similarly, when the EGP levelling valve (25) detects that the vehicle is operating under a heavy-load condition, the ILAS-PC valve (30) direct the compressed air to the plurality of suspension bellows (45) to inflate the suspension bellows (45) and simultaneously vent the plurality of lift bellows (44). By way of non-limiting example, when the vehicle is loaded with cargo, say 25-30 tonnes, the EGP levelling valve (25) detects the lower position of the chassis, indicating a heavy -load condition. The pilot pressure is then removed from the ILAS-PC valve (30), which causes the system (100) to direct the pilot pressure to the suspension bellows (45). The plurality of suspension bellows (45) is then inflated and the lift axle (20) is lowered to the ground. The lift axle (20) remains properly positioned to support the weight of the cargo, providing better stability and load distribution across the vehicle.
[0045] Referring now to figure 3a and figure 3b, a cross-sectional view of the ILAS-PC valve (30) under heavy load condition and light load condition respectively is illustrated. The ILAS-PC valve (30) includes a holding bracket (31), valve body (32), valve seat area (33) and a spool spring mechanism (36) including internal spool (35) and a spring (38). The holding bracket (31) houses and secures the ILAS-PC valve (30) assembly in place. The valve body (32) forms the main casing, accommodating ports, internal spool (35), and internal flow passages. The valve seat area (33) interface within the ILAS-PC valve (30) where the internal spool (35) sits and shifts to route the air appropriately. The internal spool (35) is the central internal element that moves in response to pilot pressure directing air flow between the ports. The spring (38) is a compression spring located beneath the internal spool (35) that pushes the internal spool (35) upward when the pilot pressure is low, and downward when the pilot pressure is high thereby providing the proper positioning during different load conditions.
[0046] Further the ILAS-PC valve (30) includes an inlet port (12) connected to the air reservoir, a suspension bellows outlet port (22), a lift bellows inlet port (11), a lift bellows outlet port (21), an exhaust port (not shown in figure) and a pilot port (4). The pilot port (4) is configured to receive the pilot pressure from the EGP levelling valve (25) to automatically shift the internal spool (35) and to control the air routing between the respective ports based on load condition thereby inflating or deflating the plurality of suspension bellows (44) and plurality of lift bellows (45) without requiring electrical input. Specifically, the spool-spring mechanism (36) in the ILAS-PC valve (30) is configured to shift positions in response to pilot pressure at the pilot port (4) to direct airflow between inlet port (12) connected to the air reservoir and the suspension bellows outlet port (22) or between the lift bellows inlet port (11) and the lift bellows outlet port (21).
[0047] Referring again to Figure 3a and 3b, the pilot port (4) is positioned at the top of the ILAS-PC valve (30) and is in fluid communication with the EGP levelling valve (25). The pilot port (4) directs air pressure proportional to the vertical displacement of the chassis of vehicle into the ILAS-PC valve (30) thereby commanding the internal spool (35) to shift between upward position and downward position. The internal spool (35) is biased by the spring (38), which returns it to its default position when pilot pressure is below a defined threshold.
[0048] During the operation of the ILAS-PC valve (30) as illustrated in figure 3a and figure 3b, when the EGP levelling valve (25) outputs a pilot pressure greater than 3.5 bar, the internal spool (35) shifts downwards to allow airflow from the inlet port (12) connected to the air reservoir to the suspension bellows outlet port (22) inflating the plurality of suspension bellows (44) and deflating a plurality of lift bellows (45) through the lift bellows outlet port (21) to the exhaust port. Similarly, when the EGP levelling valve (25) outputs a pilot pressure less than 3.5 bar, the internal spool (35) shifts to allow airflow from the lift bellows inlet port (11) to the lift bellows outlet port (21) inflating the plurality of lift bellows (45) and deflating the plurality of suspension bellows (44) through suspension bellows outlet port (22) to the exhaust port.
[0049] More specifically when the vehicle is in a heavy-load condition as shown in Figure 3a, the chassis of the vehicle settles lower, causing the EGP levelling valve (25) to output a pilot pressure greater than 3.5 bar to the pilot port (4). The high pilot pressure compresses the spring (38) and shifts the internal spool (35) downward within the valve body (32). As a result, the compressed air flows from the inlet port (12) connected to the air reservoir to the suspension bellows outlet port (22), thereby inflating the plurality of suspension bellows (44). Simultaneously, the plurality of lift bellows (45) is vented by allowing the air to flow from the lift bellows outlet port (21) to the exhaust port. The flow path is marked in the figure 3a by label =A which is inlet port 12 (supply to suspension), and B which is suspension bellows outlet port (22) (outlet to suspension). The label ≠A represents the lift bellows outlet port (21) which is being exhausted.
[0050] Similarly, as shown in figure 3b, when the vehicle is in a light-load condition, the chassis position of the vehicle rises, and the EGP levelling valve delivers (25) a pilot pressure below 3.5 bar to pilot port (4). In this condition, the spring (38) pushes the internal spool (35) upward, causing the ILAS-PC valve (30) to reconfigure air flow. Now, the compressed air flows from the lift bellows inlet port (11) to the lift bellows outlet port (21), inflating the plurality of lift bellows (45), while the suspension bellows (44) are vented through suspension bellows outlet port (22) to the exhaust port. The condition is shown in the figure with A = the lift bellows inlet port 11 (supply to lift bellows), and =A port the lift bellows outlet port (21), (lift bellows outlet). The label ≠B represents the venting of suspension bellows through suspension bellows outlet port (22).
[0051] Referring to Figure 4, an embodiment of the invention is illustrated, showing the system (100) implemented on a tandem axle trailer configuration, in which both the lift axles (20) are equipped with automatic lift and drop capability using ILAS-PC valve (30). In this embodiment, the pilot pressure generated by the EGP levelling valve (25) is supplied to pilot port (4) of the ILAS-PC valve (30), which in turn controls the internal spool (35) and spool-spring mechanism (36). The air supply from the air reservoir (10) is routed through a pressure safety valve (25) and into the ILAS-PC valve (30). Depending on the load condition, the ILAS-PC valve (30) routes the air accordingly. In the case of a heavy load condition, the high pilot pressure shifts the internal spool (35) to route air from the inlet port (12) connected to the air reservoir (10) to the suspension bellows outlet port (22), to inflate the plurality of suspension bellows (44), while simultaneously exhausting air from the plurality of lift bellows (45) through the lift bellows outlet port (21), to the exhaust port (not shown). In light loaded conditions, the pilot pressure is reduced causing the internal spool (35) to shift and redirect air from the lift bellows inlet port (11) to the lift bellows outlet port (21), to inflate the plurality of lift bellows (45), while the plurality of suspension bellows (44) is vented through the suspension bellows outlet port (22).
[0052] Referring to Figure 5, another embodiment of the invention is illustrated, where the ILAS-PC valve (30) is applied to a tri-axle trailer configuration, but only the first axle (front-most) is equipped with automatic pneumatic lift and drop functionality. The embodiment is a partial implementation of the ILAS-PC valve (30) for cost-effective deployment in trailers where only one axle requires actuation based on the load. The air supply from the air reservoir (10) is routed through the pressure safety valve (23) and into a height levelling valve which acts as the EGP levelling valve in this configuration. The height levelling valve (24) modulates the output pressure based on chassis displacement and sends the corresponding pilot pressure to the pilot port (4) of the ILAS-PC valve (30). Similar to the previous embodiment, the ILAS-PC valve (30) uses pilot-actuated internal spool (35) movement to control air routing. During heavy load conditions, the pilot pressure exceeds 3.5 bar, triggering airflow from port the inlet port (12) connected to the air reservoir (10) to the suspension bellows outlet port (22), thereby inflating the plurality of suspension bellows (44) and lowering the lift axle (20). During the light-load conditions, the reduced pilot pressure enables air routing from the lift bellows inlet port (11) to the lift bellows outlet port (21), inflating the plurality of lift bellows (44) and raising the lift axle (20), while the plurality of suspension bellows (45) is vented through the suspension bellows outlet port (22).
[0053] Referring again to Figure 1 the system (100) includes a solenoid-actuated directional control valve (40) to temporarily override the pneumatic control valve. The solenoid-actuated directional control valve from herein afterwards referred as ILAS-EC valve (40) which is Integrated Laden Axle Sensing-Electronic control valve Specifically, the ILAS-EC valve (40) works independently of the EGP levelling valve (25) and is activated by the driver’s inputs through reverse or turn signals rather than the vehicle's load condition. Specifically, during reversing or turning, the ILAS-EC valve (40) takes control of lift axle (20) and inflates the plurality of lift bellows (44) for a preset duration. The ILAS-EC valve (40) is connected to the air reservoir (10) and directs air to the plurality of lift bellows (44) independent of the EGP levelling valve (25).
[0054] The ILAS-EC valve (40) is electrically coupled to an electronic timer module (60) and the control module (50) to temporarily inflate the plurality of lift bellows (44) for a preset duration. In the present invention the preset duration ranges between 90-120 seconds as controlled by the electronic timer module (60). The action temporarily raises the lift axle (20) reducing drag and improve the manoeuvrability during reversing or tight cornering. After the preset time expires, the ILAS-EC valve (40) automatically deactivates and the control automatically switches back to the ILAS-PC valve (30) based on the load condition. Specifically, the system (100) includes logic for trailer reverse assist, wherein the control module (50) intercepts the reverse signal from the prime mover of the vehicle through a standard trailer-to-tractor electrical interface (such as the ISO 1185 7-pin power connector) and momentarily activates the ILAS-EC valve (40) to lift the first or front lift axle (20) of the trailer while keeping the reverse gear engaged. Further, the control module (50) includes trailer turn assist functionality. More specifically when the turn signal is activated, the control module (50) waits for 40 seconds to differentiate between a typical lane change and a full turning manoeuvre. If the turn signal remains active for 40 seconds, the ILAS-EC valve (40) is activated to lift the front lift axle (20) of the trailer for a duration of 10 minutes or until the signal is turned OFF, whichever occurs earlier.
[0055] In the present invention the control module (50) is arranged within the vehicle cabin is electrically connected to at least one of the manual override switches, reverse signal, and turn signal indicator. The exact physical location of the control module (50) within the vehicle may vary depending on the design of the vehicle. The control module (50) controls the activation of the ILAS-EC valve (40) for proper control of the lift axle (20). The control module (50) also includes a relay circuit with input terminals corresponding to the connectors of the vehicle for receiving the reverse signal, and the turn signal indicator. Further, the control module (50) includes a tilt angle sensing feature that monitors the inclination of the trailer. If the tilt angle exceeds 12 degrees, the system (100) generates an indication to the driver to activate a traction assist mode, which temporarily lifts the lift axle (20) for a configurable duration between 90 and 120 seconds.
[0056] Specifically, when the vehicle is reversing or turning the control module (50) receives the electrical signal, and the electronic timer module (60) is triggered to energize the ILAS-EC valve (40). The ILAS-EC valve (40) temporarily inflates the plurality of lift bellows (45), raising the lift axle (20) for a short time to facilitate easier turning or reversing. For example, in tight spaces such as a warehouse or dock, lifting the lift axle (20) momentarily reduces resistance, allowing for smoother turns or more precise backing manoeuvres. After the preset timer expires for example after 8 seconds, the ILAS-EC (40) valve deactivates, and the system returns to pneumatic control based on the load condition of the vehicle. However, if the EGP levelling valve (25) detects that the trailer is heavily loaded, such as carrying 30 tonnes, the control module (50) overrides the ILAS-EC valve (40) preventing the lift axle (20) from lifting even if the reverse signal or turn signal is engaged. Particularly the control module (50) is configured to prioritize the ILAS-PC valve (30) over the ILAS-EC valve (40) when the lift axle (20) is not lifted during a loaded condition of the vehicle such that the lift axle (20) stays lowered when the vehicle is carrying significant amount of weight.
[0057] Further, the control module (50) disables the activation of the ILAS-EC valve (40) when the load condition detected by the EGP levelling valve (25) corresponds to a payload above a predetermined threshold. For example, if the payload is above 25 tonnes, the control module (50) prevents the ILAS-EC valve (40) from being activated, keeping the lift axle (20) remains lowered to maintain the stability of the vehicle.
[0058] The system further includes an exhaust control valve (66) and a pressure control valve (67), work in conjunction with the ILAS-PC valve (30) and ILAS-EC valve (40) to manage the air flow. The exhaust control valve (66) controls the exhaust of air from the system (100) such that air is vented in a controlled manner when the plurality of lift bellows (45) or plurality of suspension bellows (44) are deflated. Further the exhaust air discharged from the ILAS-PC valve (30) and the ILAS-EC valve (40) is directed through a check valve (not shown in figure). Specifically, the exhaust control valve (66) helps to direct the exhaust air through the check valve, which permits reverse air flow when a pressure differential of approximately 0.4 bar is present. The pressure control valve (67) regulates the pressure levels within the system (100) to maintain the proper functioning of the plurality of lift bellows (45) and plurality of suspension bellows (44). The pressure control valve (67) further maintains a consistent and safe pressure in the plurality of lift bellows (45) and plurality of suspension bellows (44), allowing them to operate correctly under varying load conditions and preventing over-inflation or under-inflation that could damage the components. Further, the system (100) optionally includes a provision for an e-SIM module configured to transmit GPS position and vehicle operational data to authorized mobile devices or fleet management platforms.
[0059] Referring now to Figure 5, a method (200) for automatic control of lift axles (20) in a vehicle is provided. The method (200) is described in conjunction with the system (100).
[0060] The method (200) starts at step 210
[0061] At step 220, compressed air from an air reservoir (10) is supplied through a pressure protection valve (15) to the system (100). Specifically, the compressed air is supplied from the air reservoir (10) through the pressure protection valve (15) to the system (100) such that the air is only allowed to flow to the suspension system when the pressure in the air reservoir (10) has reached an appropriate threshold. In the present invention, the threshold pressure is configured between 5 – 6 bar.
[0062] At step 230, the load condition of the vehicle is detected using a EGP levelling valve (25) mechanically linked to the vehicle. The EGP levelling valve (25) is mechanically linked to the chassis or suspension and monitors the vertical displacement of the vehicle, indicating whether the vehicle is carrying a light load or a heavy load.
[0063] At step 240, the pilot pressure is directed to the pilot port (4) of the ILAS-PC (30). Specifically, the pilot port (4) is in pneumatic communication with a EGP levelling valve (25) which is mechanically coupled to the vehicle chassis or suspension. The EGP levelling valve (25) detects variations in the vehicle's load condition by measuring changes in the suspension height and produces a proportional pneumatic signal which is the pilot pressure. Specifically, when the vehicle is heavily loaded, the EGP levelling valve (25) outputs a higher pilot pressure for e.g., above 3.5 bar, whereas in light load conditions, the pilot pressure is lower for e.g., below 3.5 bar. This pilot pressure is routed into the pilot port (4) of the ILAS-PC valve (30) to initiate the load responsive control of the lift axle (20) and the plurality of the suspension bellows (44).
[0064] At step 250, an internal spool (35) of the ILAS-PC valve (30) is actuated in response to the pilot pressure to control the routing of the compressed air through an inlet port (12) to a suspension bellow outlet port (22) and a lift bellows inlet port (11) to a lift bellows outlet port (21). More specifically the ILAS-PC valve (30) is configured with a spool-spring mechanism (36), which allows the internal spool (35) to shift between two positions including downward position and upward position. In downward position, the internal spool (35) opens an air path from inlet port (12) to suspension bellows outlet port (22) and in the other position the internal spool (35) opens a path from inlet port (11) to lift bellows outlet port (21). The shift of the internal spool (35) regulates the flow of compressed air to either the plurality of suspension bellows (44) or the plurality of lift bellows (45) accordingly.
[0065] At step 260, a plurality of suspension bellows (44) is inflated and a plurality of lift bellows (45) are vented through the ILAS-PC valve (30) when the pilot pressure corresponds to a heavy-load condition. Specifically, when the pilot pressure corresponds to a heavy-load condition, the internal spool in the ILAS-PC valve shifts such that air flows from port (12) to port (22), thereby inflating the plurality of suspension bellows (44). This causes the lift axle (20) to lower fully to the road surface, supporting the additional payload. Simultaneously, air from the plurality of lift bellows (45) is vented through port (21) through an exhaust port, such that the lift axle (20) remains engaged with the ground.
[0066] At step 270, a plurality of lift bellows (45) and venting a plurality of suspension bellows (44) through the ILAS-PC valve (30) when the pilot pressure corresponds to a light-load condition. Specifically, when the pilot pressure corresponds to a light-load condition, the compressed air from inlet port (11) is redirected to the lift bellows outlet port (21). Similarly, air from the suspension bellows (44) is vented through outlet port (22) and the exhaust port, deflating them. The system (100) only utilizes necessary lift axles (20) when the vehicle is lightly loaded.
[0067] At step 280, receiving an electrical signal corresponding to at least one of a reverse signal, and a turn signal indicator by a control module (50). For example, during tight cornering or reversing, the system (100) inflates the plurality of lift bellows (45) regardless of load condition to momentarily raise the lift axle (20).
[0068] At step 290 an ILAS-EC (40) in communication with the control module (50) is activated using an electronic timer module (60). The ILAS-EC valve (40) is integrated with an electronic timer module (60), which is calibrated to allow inflation of the plurality of lift bellows (45) for a predetermined duration between 90 to 120 seconds.
[0069] At step 300, inflating the plurality of lift bellows (45) for a preset duration using the ILAS-EC (40). Specifically, the ILAS-EC valve (40) in connection with the control module (50) is activated using an electronic timer module (60) to inflate the plurality of lift bellows (45) for a preset duration in response to the electrical signal. More specifically, when the control module (50) receives the electrical signal, it triggers the electronic timer module (60) which energizes the ILAS-EC valve (40). The ILAS-EC valve (40) causes the plurality of lift bellows (45) to inflate temporarily, raising the lift axle (20) for the preset duration (between 90 to 120 seconds in the present invention).
[0070] At step 310, the s ILAS-EC valve (40) is deactivated after expiration of the preset duration, wherein during a detected heavy-load condition, the control module (50) prevents actuation of the ILAS-EC valve (40) such that the plurality of lift bellows (45) remain vented irrespective of any received electrical signal. More particularly once the preset duration has expired, the control module (50) deactivates the s ILAS-EC valve (40) and the system (100) returns to the normal pneumatic logic based on the load condition. If the EGP levelling valve detects a heavy load, the control module (50) prevents the ILAS-EC valve (40) from activating, even if the electrical signal is received such that the lift axle (20) remains lowered during heavy-load conditions for safety.
[0071] The method (200) ends at step 320.
[0072] Thus, the present invention has an advantage of providing a system and method for automatic control of a lift axle in a vehicle that overcomes the limitations of existing manual and electronically dependent systems. By combining pneumatic control with optional electronic logic, the invention enables reliable, cost-effective, and intelligent axle management. It offers seamless integration with standard trailer suspension systems, minimizes component complexity, and reduces operational risks such as axle overload or tire wear. The invention is particularly well-suited for deployment in commercial transport applications where durability, ease of maintenance, and retrofit capability are essential, thereby fulfilling both functional and economic requirements of fleet operators.
[0073] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.
, Claims:We Claim:

1. A system (100) for automatic control of lift axle (20) in a vehicle, the system comprising:
an air reservoir (10) configured to supply compressed air to the system (100);
a pressure protection valve (15) connected to the air reservoir (10) and configured to permit air flow only when a threshold pressure is reached; and
an EGP levelling valve (25) mechanically coupled to a chassis or a suspension member of the vehicle and configured to detect a load condition of the vehicle and to output a pilot pressure in response to the load condition,
characterized in that the system (100) includes:
a pilot-operated pneumatic directional control valve (ILAS-PC) (30) in fluid communication with the EGP levelling valve (25) and configured to automatically route the compressed air to inflate or deflate a plurality of suspension bellows (44) and a plurality of lift bellows (45) based on the pilot pressure based on the load condition of the vehicle, thereby controlling the lifting and lowering of the lift axle (20) without electrical input;
a solenoid-actuated directional control valve (ILAS-EC) (40) configured to temporarily route compressed air to the plurality of lift bellows (45) for a predetermined duration in response to an electrical input signal from the vehicle; and
a control module (50) electrically connected to the solenoid-actuated directional control valve (ILAS-EC) (40) and configured to receive the electrical signals including at least one of a reverse gear signal and a turn signal, and to trigger the solenoid-actuated directional control valve (ILAS-EC) (40) for the predetermined duration through an electronic timer module (60),
 wherein under normal operating conditions, the pilot-operated pneumatic directional control (ILAS-PC) valve (30) maintains the automatic control based on the load condition of the vehicle and during reversing or turning, the control module (50) activates the solenoid-actuated directional control (ILAS-EC) valve (40) to temporarily lift the lift axle (20).
2. The system (100) as claimed in claim 1, wherein the control module (50) is configured to prevent the actuation of the solenoid-actuated directional control valve (ILAS-EC) (40) when the EGP levelling valve (25) detects a heavy load condition above a threshold pressure.
3. The system (100) as claimed in claim 1, wherein the pilot-operated pneumatic directional control valve (ILAS-EC) (30) includes:
an inlet port (12) connected to the air reservoir (10);
a suspension bellows outlet port (22);
a lift bellows inlet port (11);
a lift bellows outlet port (21);
an exhaust port; and
a pilot port (4) configured to receive the pilot pressure from the EGP levelling valve (25) to automatically shift an internal spool (35) and to control the air routing between the respective ports based on load condition thereby inflating or deflating the plurality of suspension bellows (44) and the plurality of lift bellows (45) without requiring electrical input.
4. The system (100) as claimed in claim 1, wherein the pilot-operated pneumatic directional control valve (ILAS-EC) (30) includes a spool-spring mechanism (36) configured to shift positions in response to pilot pressure at the pilot port (4) to direct airflow between the inlet port (12) connected to the air reservoir and the suspension bellows outlet port (22) or between the lift bellows inlet port (11) and the lift bellows outlet port (21).
5. The system (100) as claimed in claim 1, wherein when the EGP levelling valve (25) outputs a pilot pressure greater than 3.5 bar, the internal spool (35) shifts to allow airflow from the inlet port (12) connected to the air reservoir to the suspension bellows outlet port (22) inflating the plurality of suspension bellows (44) and deflating a plurality of lift bellows (45) through the lift bellows outlet port (21) to the exhaust port.
6. The system (100) as claimed in claim 1, wherein when the EGP levelling valve outputs a pilot pressure less than 3.5 bar, the internal spool (35) shifts to allow airflow from the lift bellows inlet port (11) to the lift bellows outlet port (21) inflating the plurality of lift bellows (45) and deflating the plurality of suspension bellows (44) through suspension bellows outlet port (22) to the exhaust port.
7. The system (100) as claimed in claim 1, wherein the pressure protection valve (15) is configured to block air flow to the system (100) when pressure in the air reservoir (10) is below 5-6 bar.
8. The system (100) as claimed in claim 1, wherein the solenoid-actuated directional control valve (ILAS-EC) (40) is configured to inflate the plurality of lift bellows (45) for a preset duration between 90 to 120 seconds as controlled by the electronic timer module (60).
9. The system (100) as claimed in claim 1, wherein the control module (50) is mounted within the vehicle cabin and includes a relay circuit having input terminals corresponding to vehicle connectors for receiving electrical signals from the reverse signal and the turn signal indicator.
10. The system (100) as claimed in claim 1, wherein the air discharged from the exhaust port of the pilot-operated pneumatic directional control valve (ILAS-EC) (30) and the solenoid-actuated directional control valve (ILAS-EC) (40) is directed through a check valve and is configured to permit reverse air flow when a pressure differential of 0.4 bar is present across the check valve.
11. The system (100) as claimed in claim 1, wherein the EGP levelling valve (25) is configured to detect vertical displacement of the chassis of the vehicle to determine the load condition.
12. A method (200) for automatic and manual control of lift axles (20) in a vehicle, the method (100) comprising steps of:
supplying compressed air from an air reservoir (15) through a pressure protection valve (15) to the system (100);
detecting a load condition of the vehicle using a EGP levelling valve (25) mechanically coupled to the suspension of the vehicle and configured to output a pilot pressure representing the load condition;
directing the pilot pressure to a pilot port (4) of a pilot-operated pneumatic directional control valve (ILAS-PC) (30);
actuating an internal spool (35) of the pilot-operated pneumatic directional control valve (ILAS-PC) (30) in response to the pilot pressure to control the routing of the compressed air through an inlet port (12) to a suspension bellow outlet port (22) and a lift bellows inlet port (11) to a lift bellows outlet port (21);
inflating a plurality of suspension bellows (44) and venting a plurality of lift bellows (45) through the pilot-operated pneumatic directional control valve (ILAS-PC) (30) when the pilot pressure corresponds to a heavy-load condition;
inflating a plurality of lift bellows (45) and venting a plurality of suspension bellows (44) through the pilot-operated pneumatic directional control valve (ILAS-PC) (30) when the pilot pressure corresponds to a light-load condition;
receiving an electrical signal corresponding to at least one of a reverse signal, and a turn signal indicator by a control module (50);
activating a solenoid-actuated directional control valve (ILAS-EC) (40) in communication with the control module (50) using an electronic timer module (60);
inflating the plurality of lift bellows (45) for a preset duration using the solenoid-actuated directional control valve (ILAS-EC) (40); and
deactivating the solenoid-actuated directional control valve (ILAS-EC) (40) after expiration of the preset duration wherein during a detected heavy-load condition, the control module (50) prevents actuation of the solenoid-actuated directional control valve (ILAS-EC) (40), such that the plurality of lift bellows (45) remain vented regardless of any electrical signal received.