1. A bidirectional pneumatic actuator system (100) for a vehicle transfer case, comprising: a bidirectional cylinder unit (102) mounted on the vehicle transfer case; a piston and a piston rod disposed within the bidirectional cylinder unit (102) and mechanically coupled to a shift rail fork; a first pneumatic adaptor (104) configured for High range selection and a second pneumatic adaptor (112) configured for Low range selection; a first 3/2 solenoid valve (106) fluidically coupled to the first pneumatic adaptor (104) and a second 3/2 solenoid valve (108) fluidically coupled to the second pneumatic adaptor (112); and a pressurized air reservoir (110) fluidically connected to the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108), wherein selective actuation of the first 3/2 solenoid valve (106) or the second 3/2 solenoid valve (108) supplies compressed air to opposite sides of the bidirectional cylinder unit (102) to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.

2. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the bidirectional cylinder unit (102) is mounted to the vehicle transfer case using a three-bolt mounting interface.

3. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the piston rod is coupled to the shift rail fork through a threaded connection secured by a locknut.

4. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the first pneumatic adaptor (104) and the second pneumatic adaptor (112) are integrated into a housing of the bidirectional cylinder unit (102) and positioned on opposite sides of an internal cylinder chamber.

5. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein actuation of one of the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108) pressurizes a corresponding side of the bidirectional cylinder unit (102) while venting the opposite side to atmosphere.

6. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein switching electrical power between the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108) reverses airflow and piston travel within the bidirectional cylinder unit (102).

7. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein bidirectional movement of the piston rod translates the shift rail fork to move a synchronizer sleeve for gear engagement.

8. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the bidirectional pneumatic actuator system (100) is configured to provide rapid shifting between the High range and the Low range.

9. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein electrical control of the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108) provides repeatable and reliable High range and Low range selection

10. A method (300) for providing a bidirectional pneumatic actuator system (100) for a vehicle transfer case, the method (300) comprising: mounting a bidirectional cylinder unit (102) on the vehicle transfer case; disposing a piston and a piston rod within the bidirectional cylinder unit (102) and mechanically coupled to a shift rail fork; providing a first pneumatic adaptor (104) configured for High range selection and a second pneumatic adaptor (112) configured for Low range selection; coupling a first 3/2 solenoid valve (106) fluidically to the first pneumatic adaptor (104) and a second 3/2 solenoid valve (108) fluidically to the second pneumatic adaptor (112); and connecting a pressurized air reservoir (110) fluidically to the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108), wherein selective actuation of the first 3/2 solenoid valve (106) or the second 3/2 solenoid valve (108) supplies compressed air to opposite sides of the bidirectional cylinder unit (102) to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.

Description:A BIDIRECTIONAL PNEUMATIC ACTUATOR SYSTEM FOR A VEHICLE TRANSFER CASE
FIELD OF THE DISCLOSURE
[0001] This invention generally relates to a field of bidirectional pneumatic actuator system for a vehicle transfer case, and in particular, to a bidirectional pneumatic actuator system for a vehicle transfer case and method thereof.
BACKGROUND
[0002] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.
[0003] Vehicle transfer cases commonly require reliable two-way shifting mechanisms to selectively engage High range and Low range operating modes during drivetrain operation. Such shifting mechanisms are expected to provide controlled, repeatable, and balanced actuation forces to ensure accurate movement of a shift rail and proper engagement of associated synchronizer components.
[0004] To achieve two-way shifting, conventional systems typically rely on separate pneumatic cylinders, return-spring-based actuation arrangements, or purely mechanical shifting mechanisms. A separate pneumatic cylinder arrangement is capable of providing powered motion in both shifting directions; however, it increases part count, system complexity, packaging constraints, and overall manufacturing cost.
[0005] In certain applications, mechanical shifting mechanisms are adopted as a cost-saving alternative to powered actuation systems. While such mechanisms reduce dependence on pneumatic or hydraulic components, they introduce ergonomic limitations, require increased operator effort, and often result in inconsistent shifting performance. Over prolonged use, mechanical shifting may adversely affect long-term reliability and durability of the drivetrain system.
[0006] Return spring type actuation systems are also employed, wherein powered actuation is provided in one direction and a spring force is relied upon to return the mechanism to a home position. Although this approach reduces component count and simplifies system architecture, it suffers from inherent limitations, including lower and inconsistent actuation force during a return stroke and limited adjustability of spring preload.
[0007] Additionally, return spring type actuation systems are generally unsuitable for applications requiring precise bidirectional control under varying load conditions. Such systems may exhibit reduced endurance during heavy-duty operation and are often incompatible with synchronizer-based shifting systems, which require balanced and controlled forces for accurate and smooth gear engagement.
[0008] Due to the above-described limitations, existing two-way shifting solutions may compromise operational consistency, shifting accuracy, long-term reliability, and overall user experience, particularly in demanding vehicle drivetrain applications.
[0009] Another the patent application, “CN201531482U,” titled “Shift fork type pneumatic actuator,” describes a shift fork type pneumatic actuator comprises a cylinder component and a shift fork transmission component, wherein the cylinder component comprises a cylinder, a cylinder head, a piston and a piston rod; the shift fork transmission component comprises a shift fork component, a main shaft and a box body, wherein the main shaft and the shift fork component are arranged in the box body; the main shaft is in rotational connection with the box body; the shift fork component is in transmission connection with the piston rod; the shift fork component comprises a slide shaft fixing block, a slide shaft, a slide block and a shift fork; the slide shaft fixing block is fixedly connected with the piston rod; the slide shaft is fixedly arranged in the slide shaft fixing block; the slide block is sleeved on the slide shaft and is in rotational connection with the slide shaft; the slide block is positioned in the shift fork to drive the shift fork to rotate; the slide shaft fixing block is arranged on the main shaft to drive the main shaft to rotate; a slide sleeve is also arranged on the slide shaft fixing block along the sliding direction thereof and is matched with a guiding shaft in a sliding manner; and the guiding shaft is fixedly arranged on the box body. The utility model has the beneficial technical effects of great output torque, small volume, and long service life.
[0010] Another patent application, "EP0903501A2," titled " One-side fed, double-acting, pneumatic actuators," describes The pneumatic actuator comprises at least one double-acting cylinder (11) having a tubular body (23) and two closure heads (16; 25, 28) which define a piston chamber (24) for a reciprocable piston (12); the body (23) of the cylinder (11) consists of an extruded tubular section provided with at least one longitudinal conduit (27) for the air flow, which extends in a wall between the two end portions of the tubular body (23). One of the closure heads (16; 25, 28) at an end side of the tubular body (23) is provided with air-flow passage (29, 30) for connecting one end (25, 28) of the piston chamber (24) via said longitudinal conduit (27) to an air inlet/outlet opening (20) close to the other end side of the body (23). The second closure head (16) of the cylinder (11) is in turn provided with an air inlet/outlet opening (32) connected to the end of the piston chamber (24) which is opposite the previous one. The actuator is made in the form of a single cylinder (11) or of a telescopically extending cylinder having several stages (10, 11).
[0011] In conventional vehicle drivetrain shifting systems, actuation mechanisms are largely limited to mechanical linkages, return-spring-based actuators, or single-direction powered devices that complete a shift only after manual input or delayed force reversal. Such approaches present several limitations in achieving accurate and consistent two-way shifting of a transfer case. In particular, existing systems do not provide balanced and controlled actuation forces in both shifting directions, resulting in inconsistent gear engagement, increased synchronizer wear, and a higher likelihood of shift shock or misalignment. Additionally, conventional designs do not adequately accommodate varying load conditions, operating environments, or durability requirements, thereby limiting their effectiveness in heavy-duty or precision shifting applications. As a result, traditional shifting systems are associated with reduced operational consistency, compromised long-term reliability, and an inability to deliver precise and repeatable bidirectional control required for modern transfer case architectures.
OBJECTIVES OF THE INVENTION
[0012] The objective of the present invention is to provide a bidirectional pneumatic actuator system for a vehicle transfer case that enables precise and reliable two-way shifting between High range and Low range operating modes using a single integrated actuator module.
[0013] The objective of the present invention is to eliminate the need for additional actuators, return springs, or complex mechanical linkages by integrating bidirectional actuation functionality within a compact pneumatic cylinder unit, thereby reducing overall part dependency.
[0014] The objective of the present invention is to significantly lower system complexity by minimizing component count and interfaces, thereby enabling easier assembly, simplified maintenance, and improved packaging within the vehicle transfer case environment.
[0015] The objective of the present invention is to reduce manufacturing and system cost by combining bidirectional shifting functions into a single compact actuator module without compromising shifting performance or control accuracy.
[0016] The objective of the present invention is to improve system reliability by minimizing wear points, mechanical joints, and potential failure interfaces commonly associated with multi-component or spring-based shifting mechanisms.
[0017] The objective of the present invention is to deliver balanced and controlled bidirectional actuation forces suitable for synchronizer-based shifting systems, thereby ensuring accurate gear engagement and reduced synchronizer wear.
[0018] The objective of the present invention is to enhance long-term durability of the shifting system through uniform and controlled force application during both forward and reverse actuation strokes under varying load conditions.
[0019] The objective of the present invention is to improve operational convenience and ergonomics by eliminating manual shifting effort and mechanical levers, thereby providing smoother, more consistent, and user-friendly shifting performance.
[0020] The objective of the present invention is to improve overall user experience and drivetrain performance by enabling efficient, accurate, and durable shifting through a simplified and integrated bidirectional pneumatic actuation mechanism.
SUMMARY
[0021] The present invention relates to a bidirectional pneumatic actuator system for a vehicle transfer case.
[0022] According to an aspect, a bidirectional pneumatic actuator system for a vehicle transfer case is disclosed. The bidirectional pneumatic actuator system comprises a bidirectional cylinder unit mounted on the vehicle transfer case. The bidirectional pneumatic actuator system further comprises a piston and a piston rod disposed within the bidirectional cylinder unit and mechanically coupled to a shift rail fork. The bidirectional pneumatic actuator system further comprises a first pneumatic adaptor configured for High range selection and a second pneumatic adaptor configured for Low range selection. The bidirectional pneumatic actuator system further comprises a first 3/2 solenoid valve fluidically coupled to the first pneumatic adaptor and a second 3/2 solenoid valve fluidically coupled to the second pneumatic adaptor. The bidirectional pneumatic actuator system further comprises a pressurized air reservoir fluidically connected to the first 3/2 solenoid valve and the second 3/2 solenoid valve. Further, selective actuation of the first 3/2 solenoid valve or the second 3/2 solenoid valve supplies compressed air to opposite sides of the bidirectional cylinder unit to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.
[0023] According to another aspect, a method for providing a bidirectional pneumatic actuator system for a vehicle transfer case is disclosed. The method comprises steps of mounting a bidirectional cylinder unit on the vehicle transfer case. The method further comprises steps of disposing a piston and a piston rod within the bidirectional cylinder unit and mechanically coupled to a shift rail fork. The method further comprises steps of providing a first pneumatic adaptor configured for High range selection and a second pneumatic adaptor configured for Low range selection. The method further comprises steps of coupling a first 3/2 solenoid valve fluidically to the first pneumatic adaptor and a second 3/2 solenoid valve fluidically to the second pneumatic adaptor. The method further comprises steps of connecting a pressurized air reservoir fluidically to the first 3/2 solenoid valve and the second 3/2 solenoid valve. Further, selective actuation of the first 3/2 solenoid valve or the second 3/2 solenoid valve supplies compressed air to opposite sides of the bidirectional cylinder unit to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the disclosure. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa. Furthermore, elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.
[0025] FIGS. 1 and 2 schematic views of a bidirectional pneumatic actuator system for a vehicle transfer case, according to an embodiment of the present disclosure; and
[0026] FIG. 3 illustrates a flowchart showing a method for providing the bidirectional pneumatic actuator system for a vehicle transfer case, according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0027] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.
[0028] Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the preferred, systems and methods are now described. Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.
[0029] The present invention discloses various embodiments of a bidirectional pneumatic actuator system for a vehicle transfer case. Embodiments of the present invention comprises a bidirectional cylinder unit mounted on the vehicle transfer case. Embodiments of the present invention further comprises a piston and a piston rod disposed within the bidirectional cylinder unit and mechanically coupled to a shift rail fork. Embodiments of the present invention further comprises a first pneumatic adaptor configured for High range selection and a second pneumatic adaptor configured for Low range selection. Embodiments of the present invention further comprises a first 3/2 solenoid valve fluidically coupled to the first pneumatic adaptor and a second 3/2 solenoid valve fluidically coupled to the second pneumatic adaptor. Embodiments of the present invention further comprises a pressurized air reservoir fluidically connected to the first 3/2 solenoid valve and the second 3/2 solenoid valve. Further, selective actuation of the first 3/2 solenoid valve or the second 3/2 solenoid valve supplies compressed air to opposite sides of the bidirectional cylinder unit to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.
[0030] FIGS. 1 and 2 schematic views of a bidirectional pneumatic actuator system (100) for a vehicle transfer case, according to an embodiment of the present disclosure.
[0031] In some embodiments, the bidirectional pneumatic actuator system (100) comprises a bidirectional cylinder unit (102) configured to be mounted directly on a vehicle transfer case and operatively coupled to a shift rail fork. The bidirectional cylinder unit (102) is configured to generate controlled linear motion in two opposite directions to enable selective engagement of High range and Low range operating modes. The bidirectional cylinder unit (102) is designed as a compact and integrated assembly to minimize packaging space and reduce installation complexity. The bidirectional pneumatic actuator system (100) is configured to replace conventional mechanical or spring-based shifting mechanisms. The bidirectional pneumatic actuator system (100) operates independently of manual input mechanisms. The architecture enables reliable and repeatable gear range selection during vehicle operation.
[0032] The bidirectional cylinder unit (102) comprises a piston and a piston rod disposed within a sealed chamber. Further, the piston rod is mechanically coupled to the shift rail fork through a threaded connection secured by a locknut. The threaded connection ensures precise axial force transmission during actuation. The locknut is configured to prevent loosening under vibration and repeated shifting cycles. The piston rod translates linear motion generated within the bidirectional cylinder unit (102) directly to the shift rail fork. The configuration enables accurate movement of a synchronizer sleeve associated with the vehicle transfer case. The mechanical coupling ensures consistent alignment during bidirectional actuation.
[0033] In some embodiments, the bidirectional cylinder unit (102) includes a first pneumatic adaptor (104) and a second pneumatic adaptor (112) integrated into a housing of the bidirectional cylinder unit (102) and positioned on opposite sides of an internal cylinder chamber. The first pneumatic adaptor (104) is configured for High range selection, and the second pneumatic adaptor (112) is configured for Low range selection. The pneumatic adaptors serve as interfaces for directing compressed air into the bidirectional cylinder unit (102). The arrangement allows selective pressurization of either side of the piston. The integrated configuration reduces external fittings and leakage points. The pneumatic adaptors support compact and robust pneumatic routing.
[0034] The bidirectional pneumatic actuator system (100) further comprises pneumatic pipes (114) fluidically connected between the first pneumatic adaptor (104) and the second pneumatic adaptor (112) and a pressurized air reservoir (110). The pneumatic pipes (114) are configured to convey compressed air from the pressurized air reservoir (110) to the bidirectional cylinder unit (102) during operation. The pneumatic pipes (114) are dimensioned to maintain stable airflow characteristics and minimize pressure losses. The routing of the pneumatic pipes (114) supports flexible installation within the vehicle layout. The pneumatic pipes (114) are configured to withstand vibration, temperature variation, and pressure cycling. The pneumatic pipes (114) enable reliable air delivery under varying operating conditions.
[0035] In some embodiments, the bidirectional pneumatic actuator system (100) comprises a first 3/2 solenoid valve (106) and a second 3/2 solenoid valve (108) fluidically coupled to the respective first pneumatic adaptor (104) and second pneumatic adaptor (112) through the pneumatic pipes (114). Each 3/2 solenoid valve is individually configured to control airflow to one side of the bidirectional cylinder unit (102). Upon electrical actuation, one 3/2 solenoid valve directs compressed air to the corresponding pneumatic adaptor while the opposite side vents to atmosphere. The solenoid valves are configured to operate in a mutually exclusive manner. The arrangement enables precise control of piston movement direction. The solenoid valves support rapid and repeatable actuation.
[0036] In operation, when the first 3/2 solenoid valve (106) is energized, compressed air is supplied through the pneumatic pipes (114) to the first pneumatic adaptor (104) corresponding to the High range. The supplied air drives the piston within the bidirectional cylinder unit (102) in a first direction. The piston rod translates the shift rail fork to engage the High range position. Simultaneously, the opposite side of the bidirectional cylinder unit (102) is vented through the second 3/2 solenoid valve (108). The controlled airflow ensures smooth and balanced actuation. The bidirectional pneumatic actuator system (100) enables accurate High range engagement without shock loading.
[0037] When electrical power is removed from the first 3/2 solenoid valve (106) and supplied to the second 3/2 solenoid valve (108), airflow within the pneumatic pipes (114) is reversed. Compressed air is directed to the second pneumatic adaptor (112) corresponding to the Low range, thereby pressurizing the opposite side of the bidirectional cylinder unit (102). The piston travels in a second direction opposite to the first direction. The piston rod translates the shift rail fork to engage the Low range position. The previously pressurized chamber vents to atmosphere. The bidirectional actuation completes a full shifting cycle.
[0038] In some embodiments, the bidirectional pneumatic actuator system (100) is configured to deliver balanced actuation forces in both directions of piston travel. The balanced force application ensures compatibility with synchronizer-based shifting systems requiring controlled and uniform force profiles. The bidirectional pneumatic actuator system (100) avoids force variability associated with return spring mechanisms. The controlled bidirectional actuation reduces synchronizer wear and improves engagement accuracy. The bidirectional pneumatic actuator system (100) supports operation under varying load conditions. The balanced force delivery enhances long-term durability of drivetrain components.
[0039] In some embodiments, the bidirectional cylinder unit (102) is mounted to the vehicle transfer case using a three-bolt mounting interface configured to provide rigid and stable attachment. The three-bolt mounting interface enables precise alignment between the piston rod and the shift rail fork. The rigid mounting minimizes deflection during actuation. The compact mounting configuration supports ease of assembly and serviceability. The integrated design reduces dependency on external brackets. The mounting arrangement contributes to consistent shifting performance over time.
[0040] The bidirectional pneumatic actuator system (100) provides improved operational convenience by eliminating manual levers and mechanical shifting effort. The bidirectional pneumatic actuator system (100) delivers smooth, consistent, and repeatable gear range selection through electrically controlled pneumatic actuation. The reduced component count lowers system complexity and potential failure interfaces. The integrated architecture enhances reliability and simplifies maintenance. The bidirectional pneumatic actuator system (100) improves overall user experience by ensuring accurate and durable shifting performance. The bidirectional pneumatic actuator system (100) is well suited for modern vehicle transfer case application.
[0041] FIG. 3 illustrates a flowchart showing a method (300) for providing the bidirectional pneumatic actuator system (100) for a vehicle transfer case, according to an embodiment of the present invention.
[0042] At operation 302, the bidirectional cylinder unit (102) is mounted on the vehicle transfer case. The bidirectional cylinder unit (102) is configured to generate controlled linear motion in two opposite directions to enable selective engagement of High range and Low range operating modes. The bidirectional cylinder unit (102) is designed as a compact and integrated assembly to minimize packaging space and reduce installation complexity. The bidirectional pneumatic actuator system (100) is configured to replace conventional mechanical or spring-based shifting mechanisms. The bidirectional pneumatic actuator system (100) operates independently of manual input mechanisms. The architecture enables reliable and repeatable gear range selection during vehicle operation.
[0043] At operation 304, the piston and the piston rod is disposed within the bidirectional cylinder unit (102) and mechanically coupled to the shift rail fork. Further, the piston rod is mechanically coupled to the shift rail fork through a threaded connection secured by a locknut. The threaded connection ensures precise axial force transmission during actuation. The locknut is configured to prevent loosening under vibration and repeated shifting cycles. The piston rod translates linear motion generated within the bidirectional cylinder unit (102) directly to the shift rail fork. The configuration enables accurate movement of a synchronizer sleeve associated with the vehicle transfer case. The mechanical coupling ensures consistent alignment during bidirectional actuation.
[0044] At operation 306, the first pneumatic adaptor (104) is configured for High range selection and a second pneumatic adaptor (112) configured for Low range selection. In some embodiments, the bidirectional cylinder unit (102) includes the first pneumatic adaptor (104) and the second pneumatic adaptor (112) integrated into a housing of the bidirectional cylinder unit (102) and positioned on opposite sides of an internal cylinder chamber. The first pneumatic adaptor (104) is configured for High range selection, and the second pneumatic adaptor (112) is configured for Low range selection. The pneumatic adaptors serve as interfaces for directing compressed air into the bidirectional cylinder unit (102). The arrangement allows selective pressurization of either side of the piston. The integrated configuration reduces external fittings and leakage points. The pneumatic adaptors support compact and robust pneumatic routing.
[0045] The bidirectional pneumatic actuator system (100) further comprises pneumatic pipes (114) fluidically connected between the first pneumatic adaptor (104) and the second pneumatic adaptor (112) and a pressurized air reservoir (110). The pneumatic pipes (114) are configured to convey compressed air from the pressurized air reservoir (110) to the bidirectional cylinder unit (102) during operation. The pneumatic pipes (114) are dimensioned to maintain stable airflow characteristics and minimize pressure losses. The routing of the pneumatic pipes (114) supports flexible installation within the vehicle layout. The pneumatic pipes (114) are configured to withstand vibration, temperature variation, and pressure cycling. The pneumatic pipes (114) enable reliable air delivery under varying operating conditions.
[0046] At operation 308, the first 3/2 solenoid valve (106) is fluidically coupled to the first pneumatic adaptor (104) and the second 3/2 solenoid valve (108) is fluidically coupled to the second pneumatic adaptor (112). Each 3/2 solenoid valve is individually configured to control airflow to one side of the bidirectional cylinder unit (102). Upon electrical actuation, one 3/2 solenoid valve directs compressed air to the corresponding pneumatic adaptor while the opposite side vents to atmosphere. The solenoid valves are configured to operate in a mutually exclusive manner. The arrangement enables precise control of piston movement direction. The solenoid valves support rapid and repeatable actuation.
[0047] In operation, when the first 3/2 solenoid valve (106) is energized, compressed air is supplied through the pneumatic pipes (114) to the first pneumatic adaptor (104) corresponding to the High range. The supplied air drives the piston within the bidirectional cylinder unit (102) in a first direction. The piston rod translates the shift rail fork to engage the High range position. Simultaneously, the opposite side of the bidirectional cylinder unit (102) is vented through the second 3/2 solenoid valve (108). The controlled airflow ensures smooth and balanced actuation. The bidirectional pneumatic actuator system (100) enables accurate High range engagement without shock loading.
[0048] When electrical power is removed from the first 3/2 solenoid valve (106) and supplied to the second 3/2 solenoid valve (108), airflow within the pneumatic pipes (114) is reversed. Compressed air is directed to the second pneumatic adaptor (112) corresponding to the Low range, thereby pressurizing the opposite side of the bidirectional cylinder unit (102). The piston travels in a second direction opposite to the first direction. The piston rod translates the shift rail fork to engage the Low range position. The previously pressurized chamber vents to atmosphere. The bidirectional actuation completes a full shifting cycle.
[0049] At operation 310, the pressurized air reservoir (110) is fluidically connected to the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108). Further, selective actuation of the first 3/2 solenoid valve (106) or the second 3/2 solenoid valve (108) supplies compressed air to opposite sides of the bidirectional cylinder unit (102) to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.
[0050] Various embodiments of the present invention provide significant advantages through a bidirectional pneumatic actuator system (100) for a vehicle transfer case, comprising a bidirectional cylinder unit (102) mounted on the vehicle transfer case, a piston and a piston rod disposed within the bidirectional cylinder unit (102) and mechanically coupled to a shift rail fork, a first pneumatic adaptor (104) configured for High range selection, and a second pneumatic adaptor (112) configured for Low range selection. A first 3/2 solenoid valve (106) is fluidically coupled to the first pneumatic adaptor (104), and a second 3/2 solenoid valve (108) is fluidically coupled to the second pneumatic adaptor (112), with both solenoid valves being fluidically connected to a pressurized air reservoir (110). Selective actuation of the first 3/2 solenoid valve (106) or the second 3/2 solenoid valve (108) supplies compressed air to opposite sides of the bidirectional cylinder unit (102) to move the piston and the piston rod bidirectionally and selectively engage the High range or the Low range of the vehicle transfer case. The compact and integrated design of the bidirectional cylinder unit (102) reduces overall component count and system complexity, thereby lowering manufacturing cost and maintenance requirements. Direct mechanical coupling of the piston rod to the shift rail fork enables precise and repeatable shift rail control with improved engagement accuracy. The reduced number of pneumatic interfaces minimizes leakage risk and enhances system reliability over prolonged operation. Collectively, the bidirectional pneumatic actuator system (100) delivers efficient, accurate, and durable transfer case shifting performance while improving user experience and long-term drivetrain reliability.
[0051] It has thus been seen the bidirectional pneumatic actuator system (100) for a vehicle transfer case, as described. The bidirectional pneumatic actuator system (100) in any case could undergo numerous modifications and variants, all of which are covered by the same innovative concept; moreover, all of the details can be replaced by technically equivalent elements. In practice, the components used, as well as the numbers, shapes, and sizes of the components can be whatever according to the technical requirements. The scope of protection of the invention is therefore defined by the attached claims.

, Claims:We Claim:
1. A bidirectional pneumatic actuator system (100) for a vehicle transfer case, comprising:
a bidirectional cylinder unit (102) mounted on the vehicle transfer case;
a piston and a piston rod disposed within the bidirectional cylinder unit (102) and mechanically coupled to a shift rail fork;
a first pneumatic adaptor (104) configured for High range selection and a second pneumatic adaptor (112) configured for Low range selection;
a first 3/2 solenoid valve (106) fluidically coupled to the first pneumatic adaptor (104) and a second 3/2 solenoid valve (108) fluidically coupled to the second pneumatic adaptor (112); and
a pressurized air reservoir (110) fluidically connected to the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108),
wherein selective actuation of the first 3/2 solenoid valve (106) or the second 3/2 solenoid valve (108) supplies compressed air to opposite sides of the bidirectional cylinder unit (102) to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.

2. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the bidirectional cylinder unit (102) is mounted to the vehicle transfer case using a three-bolt mounting interface.
3. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the piston rod is coupled to the shift rail fork through a threaded connection secured by a locknut.
4. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the first pneumatic adaptor (104) and the second pneumatic adaptor (112) are integrated into a housing of the bidirectional cylinder unit (102) and positioned on opposite sides of an internal cylinder chamber.
5. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein actuation of one of the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108) pressurizes a corresponding side of the bidirectional cylinder unit (102) while venting the opposite side to atmosphere.
6. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein switching electrical power between the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108) reverses airflow and piston travel within the bidirectional cylinder unit (102).
7. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein bidirectional movement of the piston rod translates the shift rail fork to move a synchronizer sleeve for gear engagement.
8. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein the bidirectional pneumatic actuator system (100) is configured to provide rapid shifting between the High range and the Low range.
9. The bidirectional pneumatic actuator system (100) as claimed in claim 1, wherein electrical control of the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108) provides repeatable and reliable High range and Low range selection
10. A method (300) for providing a bidirectional pneumatic actuator system (100) for a vehicle transfer case, the method (300) comprising:
mounting a bidirectional cylinder unit (102) on the vehicle transfer case;
disposing a piston and a piston rod within the bidirectional cylinder unit (102) and mechanically coupled to a shift rail fork;
providing a first pneumatic adaptor (104) configured for High range selection and a second pneumatic adaptor (112) configured for Low range selection;
coupling a first 3/2 solenoid valve (106) fluidically to the first pneumatic adaptor (104) and a second 3/2 solenoid valve (108) fluidically to the second pneumatic adaptor (112); and
connecting a pressurized air reservoir (110) fluidically to the first 3/2 solenoid valve (106) and the second 3/2 solenoid valve (108),
wherein selective actuation of the first 3/2 solenoid valve (106) or the second 3/2 solenoid valve (108) supplies compressed air to opposite sides of the bidirectional cylinder unit (102) to move the piston and the piston rod bidirectionally and selectively engage a High range or a Low range of the vehicle transfer case.