Pressure and temperature compensated control valve assembly

A pressure and temperature compensated valve assembly includes a flow valve allowing inflation flow from a control port to a tire port and controlling deflation flow from the tire port to the control port. A throttle valve restricts deflation flow between the tire port and the control port when deflating the tire at high flow rates or when tire pressure is high, thus enabling the flow valve to be closed. The throttle valve includes a throttle diaphragm that throttles in response to flow from the tire port and which does not restrict inflation flow from the control port. The valve assembly further includes a temperature responsive member engaging the flow valve, and which deforms in response to a change in temperature in the valve assembly, thus negating temperature effects on the flow valve, allowing the flow valve to close at a consistent force across a range of operating temperatures.

FIELD OF INVENTION

The present disclosure relates generally to valves, and more particularly to a pressure and temperature compensated control valve assembly of the type used in central tire inflation systems for controlling the deflation and inflation of a tire.

BACKGROUND

A central tire inflation system (CTIS) provides mobility enhancement through tire pressure adjustment and maintenance for on/off highway, commercial, non-commercial and tactical wheeled vehicles. An ideal CTIS provides fast inflation and deflation rates, enabling a vehicle to efficiently traverse surfaces having different hardness. For example, tires may be deflated, providing a larger wheel surface area for traversing relatively soft ground. System components are ideally closed from external environments to achieve long air seal life through reduction in moisture and contaminants and through enabling de-pressurization of seals when not actively adjusting tire pressures.

A typical CTIS includes a control interface providing manual and/or automatic adjustment of tire pressures. The control interface is communicatively connected to a compressor for providing air to the tires, and to a pneumatic control unit. The pneumatic control unit is responsive to the control interface and is communicatively connected between the compressor and a system of air transfer passages connected to and/or formed within the vehicle, such as in the frame and wheels. Rotary unions often communicatively connect the air transfer passages in the wheel to the air transfer passages in the remainder of the vehicle. A CTIS often also includes a wheel valve assembly, such as a wheel control valve assembly, disposed at each wheel to provide control of deflation and inflation of the respective tire.

Deflation rates are typically set by the primary controlling orifice in the wheel valve assembly. Faster deflation rates demand a larger cross-sectional flow area, such as at lower desired tire pressures where deflation rates are most affected. Closing forces required to seal against the control orifice of the wheel valve assembly increase with respect to increases in the effective area that the tire pressure works upon and/or with respect to increases in the desired maximum operating tire pressure. The closing force must be sufficient to overcome the desired maximum operating tire pressure, maintaining closure of the valve, while also being sufficient to react against resulting back pressure in the system, such as in the air transfer passages, due to the inherent downstream restriction of air flow through the lines and fittings of the air transfer passages, thus enabling the valve assembly to close. The minimum obtainable tire pressure control is therefore impacted by the maximum required closing force resulting from these variables.

Wheel valve assembly performance is also impacted by the effects of temperature and durability of components of the wheel valve assembly. Trapped volumes within the wheel valve assembly are subjected to the varying pressures due to varying operating temperatures of the wheel valve assembly. Closing forces must be capable of overcoming changes in pressure in these volumes. The wheel valve assembly must therefore be able to compensate for the high closing forces required at maximum desired inflation pressures and low temperatures, and remain open in order to deflate to the minimum desired inflation pressures at high temperatures at the desired deflation rate.

SUMMARY OF INVENTION

One aspect of the present disclosure provides a control valve assembly including a valve body having a control port and a tire port, the valve body defining a flow chamber and a regulation chamber disposed between the control port and the tire port. The control valve assembly also includes a flow valve disposed in the flow chamber to control flow between the flow chamber and the regulation chamber, the flow valve being biased in a flow closed position and movable between the flow closed position and a flow open position in response to pressure in the flow chamber. The control valve assembly further includes a throttle valve disposed in the regulation chamber to restrict flow from the regulation chamber to the flow chamber, the throttle valve including a throttle valve seat and a throttle diaphragm for moving with respect to the throttle valve seat. The throttle valve is movable between a throttle open position of the throttle valve, where the throttle diaphragm is spaced a distance from the throttle valve seat and a throttle throttling position of the throttle valve, where the throttle diaphragm is spaced nearer the throttle valve seat than in the throttle open position. The throttle diaphragm has opposite sides each in communication with pressure in the regulation chamber, and flow through the regulation chamber effects a pressure differential across the throttle diaphragm causing the throttle diaphragm to move between the throttle open and throttle throttling positions.

The opposite sides of throttle diaphragm may include a first side positioned in the path of flow from the tire port and a second side positioned in the path of flow from the flow chamber.

The throttle diaphragm may be disengaged from any biasing member in both the throttle open and throttle throttling positions of the throttle valve.

Absent flow through the regulation chamber, the throttle diaphragm may be normally in the throttle open position via equal pressures acting on opposite sides of the throttle diaphragm.

The throttle diaphragm may be made of a metallic material.

The throttle valve seat may be adjustably positionable with respect to the throttle diaphragm, thereby setting the flow rate at which the throttle valve throttles.

The throttle diaphragm may be radially inwardly spaced from the valve body, thereby allowing flow through the regulation chamber to flow about all sides of the throttle diaphragm.

The valve body may further define a biasing member chamber, and the control valve assembly may further include a temperature responsive member disposed in the biasing member chamber and engaging the flow valve, the temperature responsive member being deformable in response to change in temperature to counter a pressure affecting the flow valve, the pressure being caused by the change in temperature.

The flow valve may include a flow diaphragm for controlling flow through the flow valve.

The flow diaphragm may be made of a metallic material.

The control valve assembly may further include an orifice extending between the flow chamber and the regulation chamber, wherein a first side of the orifice is engageable by the flow valve to open and close the flow valve, and wherein a second side of the orifice is disposed adjacent the throttle diaphragm to restrict flow from the regulation chamber to the flow chamber as the throttle diaphragm moves with respect to the second side of the orifice.

The throttle valve may further include a throttle valve housing at least partially enclosing the throttle diaphragm, wherein the throttle valve housing includes at least one aperture formed through the throttle valve housing, the at least one aperture extending between a first side open to the orifice and a second side open to the tire port, and wherein the at least one aperture has an effective area less than the orifice extending between the flow chamber and the regulation chamber.

The temperature responsive member may include an aperture extending between opposite sides of the temperature responsive member, thereby allowing pressure equalization across the temperature responsive member.

The temperature responsive member may be deformable towards the flow valve in response to relatively cold temperatures, and wherein the temperature responsive member is deformable away from the flow valve in response to relatively hot temperatures.

The temperature responsive member may be separated from flow between the control port and the tire port.

Another aspect of the present disclosure provides a control valve assembly including a valve body including a control port and a tire port. The control valve assembly further includes a flow valve disposed in the valve body for controlling flow between the control port and the tire port, the flow valve including a valve member and a biasing member for biasing the valve member in a closed position. A throttle valve is disposed in the valve body for restricting flow through the flow valve. A transition orifice is disposed in the valve body between the flow valve and the throttle valve, a first side of the transition orifice being engageable by the flow valve, and a second side of the orifice being disposed adjacent the throttle valve. A temperature responsive member is disposed in the valve body and engages the biasing member, the temperature responsive member being deformable in response to change in temperature to vary a pressure acting on the flow valve, the pressure being caused by the change in temperature.

The temperature responsive member may include an aperture extending between opposite sides of the temperature responsive member, thereby allowing pressure equalization across the temperature responsive member.

The temperature responsive member may be deformable towards the biasing member in response to relatively cold temperatures, and wherein the temperature responsive member is deformable away from the biasing member in response to relatively hot temperatures.

The temperature responsive member may be separated from flow between the control port and the tire port.

According to yet another aspect of the present disclosure, a method of adjusting tire pressure of a tire is provided. The method includes the steps of controlling inflation and deflation flow between a source and the tire via a flow valve, restricting deflation flow between the source and the tire via a throttle valve, and moving air about opposite sides of a throttle diaphragm of the throttle valve to throttle the throttle valve, wherein the throttle diaphragm is separated from contact with any biasing member.

The method may further include the step of adjusting a force of a biasing member acting on the flow valve via deformation of a temperature responsive member engaging the biasing member.

Restricting deflation flow between the source and the tire may include throttling the throttle valve in response to increased flow from the direction of the tire, thereby enabling the flow valve to close.

The method may further include the step of adjustably positioning a throttle valve seat of the throttle valve with respect to the throttle diaphragm of the throttle valve, thereby setting the flow rate at which the throttle valve throttles.

The foregoing and other features are hereinafter described in greater detail with reference to the accompanying drawings.

DETAILED DESCRIPTION

The principles of the present disclosure have particular application to central tire inflation systems (CTISs) for quickly adjusting the tire pressure of tires of wheeled vehicles, such as commercial trucks, off-road vehicles, tactical wheeled vehicles, etc. Of course, the principles of the present disclosure may be useful in other applications requiring quick inflation and/or deflation of an inflatable member or body, or even in applications requiring the use of a control valve assembly including a throttle valve.

Referring now in detail to the drawings, and initially toFIG. 1, a central tire inflation system (CTIS) is shown at12. The CTIS12may be configured to function with a wheeled vehicle or with any other device including inflatable members. The CTIS12is configured to adjust pressure of any suitable number of inflatable members, such as tires14of wheels16.

The CTIS12includes a control interface18providing manual and/or automatic adjustment of tire pressures of the tires14. The control interface18may be accessed by a user or may include any suitable processor for automatically adjusting tire pressure of the tires14. The control interface18is communicatively connected to a compressor20for providing air to the tires14.

A pneumatic control unit22is responsive to the control interface18and is communicatively connected to the compressor20and a system of main air transfer passages24, such as being connected between the compressor20and the system of main air transfer passages24as depicted. The pneumatic control unit22may include a port for venting to atmosphere. The main air transfer passages24may be separate from and connected to the vehicle, or alternatively they may be formed integral with the vehicle, such as being formed within a vehicle frame.

Rotary unions26communicatively connect wheel air transfer passages27to the main air transfer passages24in the remainder of the vehicle. The wheel air transfer passages27may be connected to and/or formed in the wheels16. A control valve assembly28according to the present disclosure is disposed at each wheel16to provide control of deflation and/or inflation of each respective tire14.

In other embodiments, the components of the CTIS12may be arranged in any other suitable order of connection.

Turning now toFIGS. 2-6, a pressure and temperature compensated control valve assembly according to the present disclosure is shown at30. The valve assembly30may be used in place of a valve assembly28of the CTIS12ofFIG. 1. The valve assembly30includes a valve body32mounted to a wheel by fasteners34extending through the valve body32. The fasteners34may be bolts, rivets, screws, etc. The valve assembly30may be flush mounted to a wheel or axle, and may not require fluid transfer members, such as hoses, disposed between the valve assembly30and the wheel and/or axle. In some embodiments the valve assembly30may be mounted to another suitable location of the respective vehicle and may be fluidly connected to the wheel and/or axle via fluid transfer members, such as hoses. In this way, the valve assembly30may include ports opening directly to a tire, and may not include ports for connecting to air lines to route inflation and deflation pressure between the valve assembly30and the wheel and/or tire. In one embodiment the valve assembly30may be attached to the wheel by welding, adhesives, etc.

The valve body32includes an upper body portion38, also herein referred to as a cover38, a lower body portion40, and an intermediate body portion42disposed between the cover38and the lower body portion40. The lower and intermediate body portions40and42may be positioned with respect to one another via the fasteners34extending through radially outwardly extending attachment portions44of each of the lower and intermediate body portions40and42. The attachment portions44may or may not include threading for mating with threading of the fasteners34. In other embodiments, the fasteners34may not position the body portions40and42with respect to one another.

Fasteners46are also included for attaching the portions40and42. The fasteners46may be bolts, rivets, screws, etc. The upper body portion38is attached to the intermediate body portion42by additional fasteners48, extending at least partially through the intermediate body portion42. The additional fasteners48may be bolts, rivets, screws, etc.

In other embodiments, the portions38,40and42may be additionally or alternatively attached to one another via welding, adhesives, etc. Each of the portions38,40, and42may be made of any suitable material, such as metallic material or generally rigid plastic.

The valve body32includes numerous ports extending through at least one of the portions38,40and42. An external access valve52, such as a tank valve, is received in a manual fill port54extending through the lower body portion40. As depicted, the manual fill port54is in communication, such as constant communication, with the tire. The external access valve52provides a location for manual adjustment of tire pressure of the tire as an alternative to automatic adjustment via a respective pneumatic control unit. The valve52also enables a location for verifying tire pressure as an alternative to data which may be output by the pneumatic control unit to a respective control interface.

Other ports include an auxiliary access port56and a vent port58. The access port56may be provided during manufacturing for cross-connecting the manual fill port54with a port directly connected to the tire. A seal, such as a bearing60, is pressed into the access port56to seal the access port56after manufacturing. Alternatively, the access port56may be sealed by any other suitable plug, may be welded shut, etc. The vent port58is provided to prevent a pressure pre-load from being applied to internal valve components during manufacture by allowing a location for pressure to escape. The vent port58is sealed via a vent screw62. As shown, the vent port58extends through the cover38, while the access port56and manual fill port54extend through the lower portion40. In other embodiments the ports56and58may be suitably located elsewhere with respect to the valve body32.

Turning specifically toFIGS. 4 and 5, control ports70and a tire port72are disposed in a bottom surface74of the lower body portion40. The bottom surface74is configured to at least partially mount to the wheel. The control ports70provide for fluid communication, such as gaseous communication, liquid communication, or a combination thereof, of the valve assembly30with a control source, such as a compressor, and/or with the remainder of a CTIS. The tire port72is positioned adjacent the control ports70, although the ports70and72may be further separated in other embodiments. The tire port72provides for flow of fluid, such as liquid, gas, or a combination thereof, to and from a respective tire to which the valve assembly30is mounted. Two control ports70and one tire port72are depicted, though any suitable number, one or more, of control ports70and tire ports72may be utilized. Seals such as o-rings76and78are disposed about the ports70and72for enabling air-tight engagement between the valve assembly30and the respective wheel when the valve assembly30is flush mounted against the wheel in any suitable manner. The radially internal o-ring76is disposed about the tire port72, while the radially external o-ring78is disposed about the radially internal o-ring76, tire port72, and control ports70. The bottom surface74may include one or more recesses82for locating the o-rings76and78. A connection recess84enables fluid communication between the control ports70and is enclosed by the radially external o-ring78once the valve assembly30is mounted to the wheel.

Turning now toFIGS. 7 and 8, the valve assembly30is shown in cross-sectional views. As previously stated, the manual fill port54is fluidly connected to the tire port72. The external access valve52provides one option for control of flow between the tire port72and the external environment through the manual fill port54. Another option is to vent the tire through the control port70and into the remainder of the respective CTIS.

The portions38,40, and42and vent screw62are shown disposed adjacent one another, with seals90disposed therebetween for providing an air-tight valve assembly30. Defined by the portions38,40and42are three functional chambers92,94, and96disposed between the tire port72and the control ports70. The functional chambers92,94and96contain numerous internal components of the valve assembly30. The chambers92,94and96may be formed in any suitable portion of the valve body32, and any of the valve body portions38,40, and42may be formed integral with one another.

The chamber92is a flow chamber92, containing a flow valve100for controlling flow between the tire port72and the control ports70. In response to pressure in the flow chamber92, the flow valve100moves between a flow open position, to allow fluid to move into the tire for inflation and out of the tire for deflation, and a flow closed position, to stop flow between the tire port72and control ports70. The flow valve100includes a valve member102and a biasing member104. The biasing member104, such as a spring, biases the valve member102, and thus the flow valve100, in the flow closed position, preventing flow between the tire port72and the control ports70. A central portion103of the intermediate body portion42radially supports the biasing member104during its axial compression along a longitudinal central axis105of the valve assembly30and relative to the valve member102.

The valve member102includes a flow diaphragm106radially outwardly disposed with respect to a flow poppet110. The flow diaphragm106is elastically deformable, such as elastically bendable, to move the flow poppet110towards and away from a flow valve seat112, controlling flow through the flow valve100. The flow diaphragm106and the flow poppet110, and thus the valve member102, are concentrically aligned with an orifice, such as a transition orifice116, through the valve seat112. The orifice116connects the chamber92to the tire port72, and thus in the depicted embodiment the valve member102is concentrically aligned with the tire port72, although the valve member102may be otherwise suitably aligned in other embodiments. As shown the flow diaphragm106may have convolutions or bends formed therein enabling it to deform and moving the flow valve100between the flow open and flow closed positions. In the flow open position, the poppet110is disengaged from the valve seat112, and in the flow closed position, the poppet110is in contact with the valve seat112.

The flow diaphragm106may be made of a metallic material, while the flow poppet110may be made of a polymer, such as an elastic polymer, enabling the poppet110to form a seal with the valve seat112. Use of a metallic diaphragm provides the advantages of consistent reaction force (elasticity) that is substantially unaffected by temperature, chemicals, and aging or breakdown. The metallic diaphragm106is also substantially impermeable, thus preventing leaking into or out of a trapped volume of fluid, such as air, disposed against an upper surface of the metallic diaphragm and separated from flow between the tire port72and the control ports70. In other embodiments, the flow diaphragm106and flow poppet110may each be made of any suitable material, such as a suitable rigid or elastically deformable plastic, etc.

While the flow chamber92is defined between the intermediate body portion42and the lower body portion40, it is also defined between a lower surface of the flow diaphragm106and an upper surface of a body member120, which includes the flow valve seat112. The body member120is attached to the valve body32, such as to the lower body portion40, by one or more fasteners122, which may be bolts, screws, etc. In one embodiment the body member120may be attached via welding, adhesives, etc.

Inflation flow may enter the flow chamber92via a control port70, extending through the valve body32. The inflation flow will thus enter the flow chamber92and impact upon the flow diaphragm106. Flow, such as deflation flow, may also enter the flow chamber92from the chamber94and the tire port72. In this manner, deflation flow will enter the flow chamber92through the body member120and the transition orifice116by moving past the flow valve seat112and between the flow valve seat112and the poppet110.

Referring now to the chamber94, a lower surface of the body member120defines at least a portion of the chamber94, which is a regulation chamber94. The regulation chamber94is also defined by the lower body portion40. The flow chamber92and regulation chamber94are fluidly connected via the orifice116, which extends between each of the flow chamber92and the regulation chamber94. The regulation chamber94is thus interdisposed between the flow chamber92and the tire port72in the illustrated embodiment.

While a first end of the orifice116is at least partially defined by the flow valve seat112, a second end of the orifice116is defined by a throttle valve seat126of a throttle valve128, disposed in the regulation chamber94. The throttle valve128provides for restriction of flow between the flow chamber92and the regulation chamber94, and thus between the tire port72and the control ports70, to be discussed further. Accordingly, a first side of the orifice116is engageable by the flow valve100to open and close the flow valve100. A second side of the orifice116is disposed adjacent the throttle valve128to restrict flow through the orifice116upon throttling of the throttle valve128relative to the throttle valve seat126/second side of the orifice116.

A portion of the orifice116disposed between the flow valve seat112and the throttle valve seat126is defined by both the body member120and an adjustable insert130. The adjustable insert130includes the throttle valve seat126, although the throttle valve seat126and insert130may be separate components in other embodiments. The adjustable insert130, and thus the throttle valve seat126, is adjustably positionable with respect to a remainder of the throttle valve128, thereby setting the flow rate at which the throttle valve128throttles. As shown, the adjustable insert130is received in and adjustable relative to the body member120, such as along the central longitudinal axis105. Each of the adjustable insert130and body member120may include corresponding threads for facilitating the adjustment of the flow rate through the throttle valve128. Due to the adjustability of the throttle valve seat126positioning, the flow rate through the throttle valve128may be precisely calibrated and/or easily adjusted.

In addition to the throttle valve seat126, the throttle valve128also includes a throttle diaphragm132for moving with respect to the throttle valve seat126to move the throttle valve128between a throttle open position and a throttle throttling position, thus throttling flow through the throttle valve128and the regulation chamber94. The throttle diaphragm132is made of a metallic material, though other suitable materials may be used, such as a polymer, etc. As with the flow diaphragm106, use of a metallic diaphragm132provides the advantages of consistent reaction force (elasticity) that is substantially unaffected by temperature, chemicals, and aging or breakdown. The metallic diaphragm132is also impermeable, thus preventing leaking into or out of the tire and/or into or out of a trapped volume of fluid, such as air, disposed in the chamber96.

The throttle diaphragm132is concentrically aligned with respect to the tire port72and transition orifice116, although the diaphragm132may be otherwise suitably aligned in other embodiments. The throttle diaphragm132is also radially inwardly spaced from the valve body32via engagement with a throttle body member140, enabling flow about all sides of the throttle diaphragm132. The throttle diaphragm132is radially outwardly constrained between portions of the body member120and the throttle body member140, which form a throttle valve housing141for at least partially enclosing the throttle diaphragm132. The throttle valve housing141defines therein a diaphragm cavity142at least partially containing the throttle diaphragm.

The throttle body member140is seated in the regulation chamber94between the valve body32and the body member120. As shown, the throttle body member140is spaced between the tire port72and the orifice116. The throttle body member140is shaped to receive flow from the tire port72, which impacts the throttle body member140prior to impacting upon the throttle diaphragm132.

The throttle diaphragm132is positioned in the path of flow between the tire port72and the control ports70, such that opposite sides of the throttle diaphragm132are each in communication with pressure in the regulation chamber94. A first side of the throttle diaphragm132is positioned in the path of flow from the tire port72. A second side opposite the first side is positioned in the path of flow through the orifice116from the flow chamber92.

Both sides of the throttle diaphragm132, and also the diaphragm cavity142, are in fluid communication with a radially outward portion of the regulation chamber94disposed about the throttle valve housing141, which includes the throttle body member140. The second side of the throttle diaphragm132is in communication with the radially outward portion of the regulation chamber94via at least one restriction aperture144extending through the body member120, and thus through the throttle valve housing141. The first side of the throttle diaphragm132is in communication with the radially outward portion of the regulation chamber94via a fluid port, such as a static fluid port146, extending through the body member140, and thus through the throttle valve housing141. Though the illustrated embodiment includes one static fluid port146and two restriction apertures144, any suitable number of fluid ports146and restriction apertures144, one or more of each, may be included. In other embodiments suitable construction of the throttle valve128may include second restriction apertures144extending instead through the throttle body member140and in communication with the second side of the throttle diaphragm132.

Absent flow through the regulation chamber94/throttle valve128, or upon relatively low flow through the regulation chamber94/throttle valve128, equal pressures affect the opposite sides of throttle diaphragm132. Because the opposite sides of the throttle diaphragm132are each in communication with pressure in the regulation chamber94, the throttle diaphragm132is normally biased in the throttle open position caused by the pressure balance across the diaphragm132. In the throttle open position a radially inward portion of the throttle diaphragm132is spaced from body member120and from the throttle body member140. Due to this pressure compensation across the throttle diaphragm132, the illustrated embodiment of the throttle valve128does not include additional biasing members affecting the throttle diaphragm132. Rather, the throttle diaphragm132is disengaged from any biasing member such that it is separated from contact with any biasing member.

Flow received through the regulation chamber94/throttle valve128and from the tire port72, such as high deflation flow, causes a pressure differential across the throttle diaphragm132causing it to first move toward the throttle throttling position. In the throttle throttling position, the throttle diaphragm132is spaced nearer the throttle valve seat126as compared to spacing between the throttle diaphragm132and the throttle valve seat126when the throttle valve is in the throttle open position. Continued flow causes the throttle diaphragm132to throttle between the throttle open and throttle throttling positions. The flow rate through the throttle valve128is at least partially controlled via positioning of the adjustable insert130relative to the normally open position of the throttle diaphragm132.

Particularly, deflation flow received from the tire port72first impacts the throttle body member140and then moves about the valve housing141. The flow enters the diaphragm cavity142via the plurality of restriction apertures144, and then flows into the flow chamber92via the transition orifice116. The flow through the relatively small cross-section of the restriction apertures144and into the portion of the diaphragm cavity adjacent the second side of the throttle diaphragm132causes a pressure drop on the second side of the throttle diaphragm132. The pressure drop on the second side of the throttle diaphragm132as compared to a pressure on the first side of the throttle diaphragm132adjacent the tire port72causes a pressure differential across the throttle diaphragm132. The greater the deflation flow from the tire port72through the restriction apertures144, the greater the pressure differential. Thus the throttle diaphragm132is caused to move towards the throttle valve seat126, throttling flow through the throttle valve seat126, where increased throttling is caused in the case of increased deflation flow from the tire port72. On the other hand, flow received from the flow chamber92, such as inflation flow, moves through the transition orifice116and adjustable insert130, past the throttle valve seat126, and impacts upon the second side of the throttle diaphragm132. The flow then moves through the restriction apertures144in the body member120and into the portion of the regulation chamber94disposed about the throttle body member140. Flow then moves about the throttle body member140and out through the tire port72. In this way, the throttle diaphragm132is not caused to move towards the throttle valve seat126, the throttle valve128is not throttled, and thus inflation flow from the flow chamber92/control ports70is not impeded by the throttle diaphragm132or the throttle valve128.

In use, the construction of the valve assembly30, including the flow valve100and throttle valve128, provide for efficient inflation and controlled deflation. To inflate the tire, an initial/reference pressure signal is directed through the control ports70and into the flow chamber92. The reference pressure signal opens the presently closed flow valve100by overcoming the combined reaction forces of the biasing member104, flow diaphragm106and poppet110. Pressure in the flow chamber92causes the flow diaphragm106to be moved away, such as vertically away, from the control ports70causing the flow poppet110to disengage from contact with the valve seat112. Additional pressure from the respective compressor greater than the current tire pressure maintains flow in a direction from the control ports70to the tire port72, thus inflating the tire.

To deflate the tire, an initial/reference pressure is again directed through the control ports70to open the presently closed flow valve100by overcoming the forces of the biasing member104, diaphragm106, and poppet110. However, additional pressure and flow is not supplied through the control ports70. Instead, when tire pressure is greater than the externally applied reference pressure, tire pressure is allowed to flow from the tire port72and to exit out the control ports70.

During this deflation, the throttle valve128controls the rate of deflation via pressure compensated flow control by creating a differential pressure proportional to flow through the valve assembly30and independent of tire pressure of the tire. The flow through the restriction apertures144effects a pressure differential across the throttle diaphragm132, causing the throttle diaphragm132to deflect from its normally open position towards a throttling position nearer or in contact with the throttle valve seat126. As flow continues from the tire through the tire port72and into the regulation chamber94, the throttle diaphragm132is caused to throttle between the open and throttling positions, restricting flow through the throttle valve128.

The resulting restriction in flow controls the flow rate flowing through the open flow valve100, out the control ports70, and into the system of respective air transfer passages. The pressure compensation enables the flow valve100to shut off without being unwantedly maintained in the flow open position by continued flow from the tire port72. The pressure compensation also negates a back pressure from building up in the respective air transfer passages, which might also cause the flow valve100to be unwantedly maintained in the flow open position.

The flow is additionally restricted from the regulation chamber94to the flow chamber92because the restriction apertures144have an effective area less than the transition orifice116. The combined effective flow area of this plurality of apertures144is configured to meet desired deflation rates of the respective CTIS at reduced tire pressures. Increasing flow from the tire results in a pressure differential which moves the throttle diaphragm132towards the throttle valve seat126. The throttle diaphragm132will throttle at high flow (high pressure differential) due to the deflection toward the adjustable insert130and throttle valve seat126.

For shut off of the valve assembly30upon completion of deflation or inflation, pressure is removed externally from the control ports70. Pressure drops across the valve seat112. Reduced flow through the throttle valve128results from the pressure compensating flow control of the throttle diaphragm132and flow through the restriction apertures144of the throttle valve housing141from the tire port72. The pressure compensation enables the flow valve100to close preventing continued flow through the flow valve seat112, and thus through the transition orifice116.

This shut off function is enabled both at low and high tire pressures. The cross-sectional flow area of the transition orifice116through the flow valve seat112is configured to meet desired deflate times at comparatively lower tire pressures. Additionally, the pressure compensation features of the throttle valve128(throttle diaphragm132and apertures144through the throttle valve housing141) control the deflate flow rate at comparatively higher tire pressures, allowing the flow valve member102to engage the flow valve seat112during tire deflation at the comparatively higher tire pressures. Consequently, the closing force of the flow valve100, and thus of the valve assembly30, is determined substantially by the resulting back pressure in the system at the maximum flow setting, regardless of the maximum operating tire pressure.

The use of the restriction apertures144and the throttle diaphragm132negate the need for spring-biasing the throttle valve128, thus providing a repeatable and consistent pressure compensated flow control performance as observed between a plurality of valve assemblies30. Additionally, the pressure compensation features do not require elastomers or internal seals which may result in drag and/or hysteresis of the throttle valve128. Thus the valve assembly30provides a precise and well-balanced flow rate through the valve assembly30.

The pressure compensation features provide for low sensitivity to variations in wheel end flow, large tire pressure range (both minimum and maximum), and rapid desired deflation rates at lower tire pressures. A respective pressure control unit, controlling pressure into the valve assembly30through the control ports70, is not required to provide varied deflation reference pressures correlating to the present tire pressure, thereby adding to the utility, durability, reliability, and repeatability of performance of the valve assembly30in a central tire inflation system.

In addition to the pressure compensation feature of the throttle valve128, the depicted embodiment includes a temperature compensation feature, such as a temperature responsive member150. In other embodiments, the temperature compensation feature may be included in a valve assembly30that does not include the pressure compensation features and/or the pressure compensation features may be included in a valve assembly30that does not include the temperature compensation feature.

The temperature responsive member150engages the biasing member104and is configured to deform in response to change in temperature. The deformation of the temperature responsive member150enables the valve assembly30to compensate for changes in pressure within the biasing member chamber96and flow chamber92due to changes in temperature. Accordingly, the temperature responsive member150negates temperature effects on the flow valve100, allowing the flow valve100to close at a substantially consistent force across a range of operating temperatures.

The cover38and the intermediate body portion42constrain, such as radially outwardly constrain, the temperature responsive member150within the chamber96. The chamber96is a biasing member chamber96. A disc aperture154extends through the temperature responsive member150, such as centrally through the temperature responsive member150along the central longitudinal axis105. The disc aperture154allows pressure equalization across the temperature responsive member150by enabling equal pressures to affect opposite sides of the temperature responsive member150. Other embodiments may additionally or alternatively include other apertures located at any suitable location of the member150and extending through the member150.

As depicted the temperature responsive member150may be made of longitudinally stacked disks disposed adjacent one another. The disks may be composed of one or more metallic materials and may be stacked in any suitable order providing for necessary deformation of the member150. In other embodiments any suitable number of disks, one or more, may be used, and the disks may be made of any suitable materials. The disks may be held adjacent one another via compression between the body portions38and42, welding, adhesives, etc.

The biasing member chamber96, and thus the temperature responsive member150, is separated from flow between the control ports70and the tire port72. An upper portion of the biasing member chamber96is disposed between the cover38and the intermediate body portion42. The upper portion also extends through the central portion103of intermediate body portion42supporting the biasing member104of the flow valve100. A lower portion of the chamber96is disposed between a lower surface of the intermediate body portion42(adjacent the flow diaphragm106) and the flow diaphragm106.

As depicted, the biasing member chamber96is air-tight, such as hermetically sealed, and thus contains a trapped volume of fluid, such as air. The fluid in the trapped volume is responsive to the varying temperatures to which the valve assembly30may be subjected, such as sub-freezing temperatures and/or conversely hot temperatures. The temperature responsive member150is subjected to the same fluctuation of temperature as the biasing member chamber96.

In use, the temperature responsive member150is generally flat or non-deflected in a normal state at intermediate temperatures. The temperature responsive member150is configured to deflect or deform towards the biasing member104in response to relatively cold temperatures. Movement of the temperature responsive member150causes the biasing member104to be, additionally compressed, increasing a force on the valve member102, and countering a pressure decrease in the biasing member chamber96. For example, pressure decreases in the lower portion of the biasing member chamber96disposed adjacent the valve member102due to contraction of fluid within the biasing member chamber96from the relatively cold temperatures. Conversely, the temperature responsive member150is also configured to deflect or deform away from the biasing member104in response to relatively hot temperatures. Movement of the temperature responsive member150causes the length of the biasing member104to be elongated, reducing a force on the valve member102, and countering a pressure increase in the biasing member chamber96. For example, pressure increases in the lower portion of the biasing member chamber96disposed adjacent the valve member102due to expansion of fluid within the biasing member chamber from the relatively hot temperatures. Accordingly, temperature compensation of the valve assembly30is provided by the temperature responsive member150, allowing the flow valve100to open at a substantially consistent force across a range of operating temperatures.

Trapped fluid volumes within the valve assembly30need not be vented to atmosphere to address the change in internal pressures in the biasing member chamber96affecting the flow diaphragm106. By maintaining closure of the valve assembly30with respect to an external environment, contaminants and moisture are not introduced into the valve assembly30, thus prolonging operating life and increasing operating performance of the valve assembly30. Additionally, a respective pressure control unit, controlling pressure into the valve assembly30through the control ports70, is not required to provide varied deflation reference pressures corresponding to the present pressures in the biasing member chamber96, thereby adding to the durability, reliability, and repeatability of performance of the valve assembly30. Therefore, inclusion of the temperature responsive member150in the valve assembly30may extend the operating range and life of the valve assembly30.

In summary, a pressure and temperature compensated valve assembly30includes a flow valve100allowing inflation flow from a control port70to a tire port72and controlling deflation flow from the tire port72to the control port70. A throttle valve128restricts deflation flow between the tire port72and the control port70when deflating the tire at high flow rates or when tire pressure is high, thus enabling the flow valve100to be closed. The throttle valve128includes a throttle diaphragm132that throttles in response to flow from the tire port72and which does not restrict inflation flow from the control port72. The valve assembly30further includes a temperature responsive member150engaging the flow valve100, and which deforms in response to a change in temperature in the valve assembly30, thus negating temperature effects on the flow valve100, allowing the flow valve100to close at a consistent force across a range of operating temperatures.