Patent ID: 12214760

DETAILED DESCRIPTION OF THE INVENTION

A pneumatic brake assembly for a vehicle is provided. Referring toFIGS.1-12, wherein like numerals indicate corresponding parts throughout the several views, the pneumatic brake is illustrated and generally designated at20. Certain features of the pneumatic brake20are functional, but can be implemented in different aesthetic configurations.

Turning first toFIGS.1-6, the pneumatic brake20includes a generally cylindrical housing22having a central, axially extending longitudinal axis24that runs along and passes through the center of the housing. The housing22is formed of an outer wall26that generally encloses the housing and defines an internal space inside of the housing. A single diaphragm28is disposed within the housing22and divides the internal space of the housing into two separate variable-volume chambers, namely a front chamber30and a rear chamber32. When mounted in a vehicle, the front chamber30is proximate the wheel brake (e.g. drum brake arrangement or disc brake arrangement) and the rear chamber32, being rearward of the front chamber, is spaced from the wheel brake. A push rod34having a proximate end36and an opposite distal end38is axially disposed along the central longitudinal axis24of the housing22. The proximate end36of the push rod34is disposed in the front chamber30of the housing22and terminates in a top plate40that is engaged with a surface of the diaphragm28. The distal end38of the push rod34extends outwardly from the housing22through a sealed opening42in a cover44of the housing22. In operation, the push rod34may engage slack adjusters (not shown) of a vehicle wheel brake such as a drum brake arrangement in order to engage and release the vehicle wheel brake.

A parking spring46is axially disposed in the rear chamber32of the housing22along the central longitudinal axis24, such that a central longitudinal axis of the parking spring is collinear and aligned with the central longitudinal axis24of the housing. The parking spring46engages a surface of the diaphragm28opposite the top plate40and urges the diaphragm against the top plate in a direction towards the front chamber30. A valve body48extends axially through the rear chamber32of the housing22along the central longitudinal axis24of the housing. The valve body48is also coaxial with the parking spring46and the push rod34. Particularly, the valve body48includes an elongated stem50coaxially aligned with the push rod34. The stem50extends into the push rod34through an opening52in the top plate40and is disposed in a telescoping relationship with the push rod such that the push rod slides over the stem as the push rod is extended and retracted.

A first supply passage54is in fluid communication with a valve port56in the valve body48. The first supply passage54is defined by a generally cylindrical end of the valve body that is continuous with the valve body and extends outwardly from the rear of the housing22opposite the opening52in the cover44of the housing. The valve body48includes a passageway58through the stem50in fluid communication with the valve port56, and the valve body also includes a plurality of open and closeable transfer ports60in fluid communication with the rear chamber32of the housing22. The push rod34includes an internal chamber62in fluid communication with the passageway58in the valve body48. The push rod34also includes a plurality of front chamber ports64. The internal chamber62of the push rod34is in fluid communication with the front chamber30of the housing22via the plurality of front chamber ports64. A second supply passage66is in fluid communication with the rear chamber32via a plurality of rear chamber ports68. The second supply passage66is defined at least in part by a swivel fitting (banjo port)70that is fitted within a central opening72in the rear chamber32of the housing22. The swivel fitting70has a generally doughnut shaped main portion from which extends a coaxial portion that includes the rear chamber ports68and which extends into the central opening72. The swivel fitting70also includes a transverse portion that extends tangentially from the side of the doughnut shaped main portion. The valve body48is coaxial with the swivel fitting70such that the first supply passage54is disposed within the second supply passage66and extends through the doughnut shaped main portion of the swivel fitting, The doughnut shaped main portion and the coaxial portion of the swivel fitting70thereby surround the first supply passage54. As described in more detail below, the first supply passage54can receive compressed air from a compressed air source such as an air reservoir to deliver the compressed air to the front chamber30of the housing22through the valve body48and the push rod34, and also provides a reverse path for exhaust of compressed air from the front chamber of the housing. Similarly, the second supply passage66can receive compressed air from the compressed air source to deliver the compressed air to the rear chamber32of the housing22, and also provides a reverse path for exhaust of compressed air from the rear chamber of the housing.

An internal transfer valve74is disposed in the valve body48and is movable in a sliding manner within the valve body. Sliding movement of the internal transfer valve74inside of the valve body48opens and closes the transfer ports60. The internal transfer valve74has a generally tubular sidewall76defining an internal passageway. A nose78caps one end of the tubular sidewall76, and the opposite end80of the sidewall is open. The nose78of the internal transfer valve74is receivable in the valve port56in the valve body48to close the valve port, and an annular flange81extending into the passageway58(and in which the valve port56is formed) defines a valve seat for the internal transfer valve. The internal transfer valve74includes a plurality of supply ports82in the sidewall76adjacent the nose78. The supply ports82are in fluid communication with the passageway58in the valve body48on either side of the internal transfer valve74. The sidewall76of the internal transfer valve74includes a stepped portion83, and the valve body48includes an internal shoulder84that defines a stop for the stepped portion of the internal transfer valve. A valve spring85is disposed within the internal passageway defined by the tubular sidewall76of the internal transfer valve74. The stepped portion83of the sidewall76defines a spring seat86, and the valve spring85is in urged engagement with the spring seat and the internal shoulder84of the valve body48.

The valve body48further includes a plurality of balance ports87in fluid communication with the rear chamber32of the housing22. A balance chamber88is in fluid communication with the rear chamber32via the balance ports87in the valve body48. The balance chamber88is defined by the stepped portion83in the sidewall76of the internal transfer valve74, an annular protrusion89extending outwardly from the sidewall of the internal transfer valve, a portion of the sidewall between the stepped portion and the annular protrusion, and an inner surface90of the valve body48. The stepped portion83in the sidewall76and the annular protrusion89contact the inner surface90of the valve body to seal the balance chamber88disposed within the valve body48.

With reference now particularly toFIGS.4-12, the pneumatic brake20may be operated in a resting mode, an activation mode in which a brake function is actuated, and a deactivation mode in which the brake function is deactivated. The positional states of the diaphragm28, the push rod34including top plate40, and the parking spring46when the brake function is actuated are shown inFIG.4, and their positional states when the brake function is deactivated are shown inFIG.5. As shown inFIG.4, in the resting mode no compressed air is present in either the front chamber30or the rear chamber32of the housing22, such that the spring force of the parking spring46against the diaphragm28and top plate40fully extends the push rod34out of the housing, thereby applying the vehicle brake (not shown). For example, both the front and rear chambers30,32may be vented to atmosphere via the first and second supply passages54,66, respectively. The spring force is approximately equivalent to about 50 to 70 psi of pneumatic pressure, preferably about 60 psi, which is adequate to hold the push rod34in its extended position. The brake20is operated in the resting mode, for example, when the vehicle is shut off and thus no compressed air is being produced by the vehicle for delivery to the brake20. Hence, the default state of the brake20, when the vehicle is parked and not operational, is for the brake to apply the vehicle brakes to hold the vehicle in a static (parked) position. The spring force of the parking spring46may also provide braking pressure to the top plate and push rod in an emergency mode, such as when a loss of the supply of compressed air (loss of pneumatic pressure) to the brake20occurs.

Turning toFIG.6, to deactivate the brake function and to enter the deactivation mode, compressed air at a pressure in the range of 110 to 130 psi, preferably about 120 psi, is supplied to the pneumatic brake20from a compressed air supply such as an air reservoir located on the vehicle (not shown) through the first supply passage54. The force of the compressed air in the first supply passage54pushes against the nose78of the internal transfer valve74and compresses the valve spring85, thereby opening the internal transfer valve and allowing the compressed air to travel into the valve body48. The compressed air is communicated through the supply ports82into the passageway58through the stem50of the valve body48. The compressed air passes from the passageway58into the internal chamber62of the push rod34and is communicated into the front chamber30through the front chamber ports64in the push rod. The compressed air in the front chamber30exerts pressure against the top plate40, and the force of the compressed air overcomes the spring force of the parking spring46, thereby moving the diaphragm28in the direction of the rear chamber32, retracting the push rod34, compressing parking spring46, increasing the volume of the front chamber and simultaneously decreasing the volume of the rear chamber. At the same time, the rear chamber32is vented through the second supply passage66so that the rear chamber is generally at or near atmospheric pressure. Further, if, for example, the deactivation mode is selected when the brake is in the resting mode described above, the rear chamber would already be in a state in which it is vented and generally at atmospheric pressure. Once in the deactivated state of the deactivation mode as shown inFIG.7, the front chamber is pressurized at approximately 120 psi thereby counteracting the spring force of the parking spring46. Also, the push rod34is fully retracted into the housing22, and the vehicle wheel brake (not shown) is released to disengage the brake function. The vehicle is now in a state in which it may be moved from a static (parked) position.

Turning toFIG.8, to transition from the deactivation mode to the activation mode in which the brake function is actuated, the supply of compressed air to the front chamber30is ceased, and the first supply passage54is connected to an atmospheric vent to allow for the exhaust of compressed air through the first supply passage. Particularly, the compressed air in the front chamber30travels through the rear chamber ports68into the internal chamber62of the push rod34, from the internal chamber into the passageway58in the stem50of the valve body48, through the supply ports82of the internal transfer valve74, out of the valve port56of the valve body, and into the first supply passage54. The exhaust of compressed air from the front chamber30causes the push rod34to begin to extend, due to the spring force exerted by the parking spring46. As shown inFIG.9, during the transition from the deactivation mode to the activation mode, the return force of the valve spring85slideably moves the internal transfer valve74from an open position to a closed position in which the nose78of the valve is seated in the valve port56, thereby preventing further exhaust of air through the first supply passage54. The movement of the internal transfer valve74moves the stepped portion83of the valve from a position in which it covers the transfer ports60to a position in which the transfer ports are open. Once the transfer ports60are open, compressed air from the front chamber30is transferred to the rear chamber32through the transfer ports. The internal transfer valve74thereby provides a path for the compressed air to travel from the front chamber30to the rear chamber32to assist with the brake application force requirements. Simultaneously, as shown inFIG.10, compressed air from the source of pressurized air (air reservoir) is supplied to the rear chamber32through the second supply passage66and the rear chamber ports68. Also, compressed air in the rear chamber32travels through the balance ports87into the balance chamber88. The combined action of the compressed air supplied to the rear chamber32via the second supply passage66as well as from the front chamber30(as shown inFIG.9) quickens the speed at which the pneumatic brake20moves from the deactivation mode to the activation mode. As there is a delay in the supply of compressed air to the rear chamber32from the second supply passage66, the internal transfer valve74provides a shorter path for air to travel into the rear chamber hence increasing the speed of brake application. Additionally, the combined force of the compressed air in the rear chamber32and the force exerted by the parking spring46quicken the speed at which the diaphragm28moves the top plate in the direction of the front chamber30, thereby extending the push rod34out of the housing22. Turning toFIG.11, when the pressure in the balance chamber88exceeds the return spring force of the valve spring85, the pressure in the balance chamber is exerted against the stepped portion83of the internal transfer valve74, thereby compressing the valve spring and moving the internal transfer valve from a closed to an open position in which the nose78is unseated from the valve port56. The remaining compressed air in the front chamber30then is exhausted through the first supply passage54via the supply ports82in the internal transfer valve74, and the front chamber remains vented. Compressed air continues to be supplied to the rear chamber32through the second supply passage66and rear chamber ports68, and the push rod34is fully extended to actuate the brake function in which the push rod causes the wheel brakes of the vehicle to be engaged. Thus, in the activation mode the combination of air (pneumatic pressure) being transferred from the front chamber30to the rear chamber32(i.e. removed from the front chamber30and sent to the rear chamber32via the internal transfer valve74) as well as the secondary pneumatic force provided by the additional, secondary supply of compressed air (pneumatic pressure) to the rear chamber32from the air reservoir through the second supply passage66ensures that full braking pressure/force is available and achieved.

Turning toFIG.12, to transition from the activation mode to the deactivation mode in which the brake function is deactivated and the wheel brakes are released, the supply of compressed air through the second supply passage66is stopped, and compressed air is released from the rear chamber32through the second supply passage via the rear chamber ports68by venting the second supply passage to atmosphere. At the same time, compressed air is supplied to the pneumatic brake20from the compressed air supply through the first supply passage54. The force of the compressed air in the first supply passage54pushes against the nose78of the internal transfer valve74and compresses the valve spring85, thereby opening the internal transfer valve and allowing the compressed air to travel into the valve body48. The compressed air is communicated through the supply ports82into the passageway58through the stem50of the valve body48. The compressed air passes from the passageway58into the internal chamber62of the push rod34and is communicated into the front chamber30through the front chamber ports64in the push rod. The compressed air in the front chamber30exerts pressure against the top plate40, and the force of the compressed air overcomes the spring force of the parking spring46, thereby moving the diaphragm28in the direction of the rear chamber32, retracting the push rod34, compressing parking spring46, increasing the volume of the front chamber and simultaneously decreasing the volume of the rear chamber. The pneumatic brake20is then in the deactivation mode as shown inFIG.7.

With additional reference now toFIGS.13-16, in some embodiments, one or more pneumatic brake20is included in a vehicle brake system, with each pneumatic brake being located at a wheel end of the vehicle, and each pneumatic brake being connected to an anti-lock braking system (ABS) that is a sub-system of the vehicle brake system. For example, as shown inFIGS.13and14, in certain embodiments the ABS may be a 5 port, 2 position spool valve91that controls the extension and retraction of the push rod34of the pneumatic brake20. One port92of the spool valve91is in fluid communication with the first supply passage54(which supplies air to and exhausts the front chamber30), and another port93of the spool valve is in fluid communication with the second supply passage66(which supplies air to and exhausts the rear chamber32). Further, one port94of the spool valve91is in fluid communication with a supply of compressed air (e.g., an air reservoir97), and the other two ports95,96of the spool valve are in fluid communication with an exhaust outlet (e.g., an atmospheric vent98). In one position of the spool valve91shown schematically inFIG.13, a coil of the spool valve is energized such that port94is in fluid communication with port93to supply compressed air from the air reservoir97to the second supply passage66and subsequently to the rear chamber32of the pneumatic brake20. Also, port95is in fluid communication with port92to exhaust air from the front chamber30through the first supply passage54to the atmospheric vent98. In this position, the push rod34of the pneumatic brake20is extended and the wheel brake in connection with the pneumatic brake is engaged. In the other position of the spool valve91shown schematically inFIG.14, the coil of the spool valve is disconnected (i.e., not energized) such that port94is in fluid communication with port92to supply compressed air from the air reservoir97to the first supply passage54and subsequently to the front chamber30of the pneumatic brake20. Also, port96is in fluid communication with port93to exhaust air from the rear chamber32through the second supply passage66to the atmospheric vent98. In this position, the push rod34of the pneumatic brake20is retracted and the wheel brake in connection with the pneumatic brake is released (disengaged). Optionally, each spool valve91of the system (one per pneumatic brake20) may be combined into one single ABS unit with a dual output pneumatic line routed to the wheel ends at which the pneumatic brakes are located. Also, the ABS may be electrically (e.g. EBS, brake by wire, etc.) or pneumatically (e.g., pilot signal) controlled. Further, each spool valve91may be positioned on top of the housing22of each pneumatic brake20included in the system, and a single pneumatic supply line and electrical wire may be routed to each wheel end, with the spool valves being electrically actuated (e.g. EBS, brake by wire, etc.).

The pneumatic brake20described above serves a dual function of both a parking brake and a service brake. Therefore, it should be understood from the description that the activation and deactivation of the brake function may be activation/deactivation of a service brake function for intermittent slowing down or stopping of a vehicle and/or a parking brake function for holding a vehicle in a static position for an indefinite amount of time without further attention.

In certain embodiments shown inFIGS.15and16, the brake function of the pneumatic brake20may controlled by a 4/2 proportional valve99that may be integrated into any ABS system as the proportional valve99works with a proportional voltage or current signal (depending on the controller) to adjust the spool valve between two ports. Since the proportional valve99effectively functions in the same way as ABS modulators, the proportional valve99is directly compatible with and able to be integrated into any ABS system. One port100of the valve99is in fluid communication with a source of pressurized air97, one port101is in fluid communication with an atmospheric vent98, one port102is in fluid communication with the first supply passage54, and one port103is in fluid communication with the second supply passage66. As shown by example inFIG.15, in one position of the valve99, pressurized air is fed from the source97to the first supply passage54, while air from the second supply passage66is exhausted to the vent98. Further, as shown by example inFIG.16, in the other position of the valve99, pressurized air is fed from the source97to the second supply passage66, while air from the first supply passage54is exhausted to the vent98. Proportional valves are rather fast and effective at precisely modulating flow and pressures. Alternatively, a servo valve may be used, which may have a faster and more precise reaction than the proportional valve99. A servo valve includes an internal LVDT that tracks spool position for precise spool control. The internal circuitry of a servo valve monitors the spool position via the LVDT and compares it to the input signal. The internal PID loop of the servo valve reduces the spool positional error, making the control loop even faster.

In some embodiments of the brake system, additional feedback sensors may be incorporated into the valves and chambers. These sensors may be used by the ABS, and additionally by other systems such as traction control, ESP (dynamic stability), EBD (electronic brake force distribution), EDL (electronic differential lock), and brake fault diagnostic systems. The sensors may include a stroke position sensor that tracks usage and extension limits that can be used by telematics and monitoring, and that can identify brake faults such as slack adjuster failures, chamber failures, control valve failures, pressure/line failures, and other mechanical failures. The brake system may also include line pressure transducers that monitor chamber pressures, detect pressure system/line failures, and/or detect operational failures such as the compressor, valves in the supply line, and/or tank/reservoir performance.

It is to be understood that the appended claims are not limited to express and particular compounds, compositions, or methods described in the detailed description, which may vary between particular embodiments which fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, different, special, and/or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims.

Further, any ranges and subranges relied upon in describing various embodiments of the present invention independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein. One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present invention, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range “of from 0.1 to 0.9” may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as “at least,” “greater than,” “less than,” “no more than,” and the like, it is to be understood that such language includes subranges and/or an upper or lower limit. As another example, a range of “at least 10” inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range “of from 1 to 9” includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1, which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.