Patent Application
20200180583
The present invention relates to embodiments of an apparatus and method to determine the replacement of an air dryer cartridge. Vehicles equipped with air brake systems normally have air dryers to provide clean, dry air to downstream components of the air brake system. An air dryer cartridge having desiccant material requires replacement periodically as the desiccant material becomes saturated or fouled. Today, manual systems exist that monitor the time between cartridge changes based on the time between a first manual reset and a second manual reset. These systems rely on the vehicle operator or mechanic to remember to hit the reset switch each time the cartridge is exchanged. The reset switch may be remote from the air dryer cartridge. There is a need for an improved method of determining an air dryer cartridge replacement has occurred.
Various embodiments of an apparatus for determining an air dryer cartridge has been replaced are presented. In one example, an air dryer assembly comprises a first air dryer cartridge; an air dryer base for receiving the first air dryer cartridge; and a state change device positioned between the air dryer cartridge and air dryer base. The state change device changes from a first state to a second state in response to the first air dryer cartridge being removably attached to the air dryer base, changes from the second state to a third state in response to the first air dryer cartridge being removed from the air dryer base and changes from the third state to the first state in response to a second air dryer cartridge being removably attached to the air dryer base.
In accordance with another aspect, various methods of determining a cartridge change on an air dryer are presented. In one example, a method for determining an air dryer cartridge replacement comprises receiving a signal from a state change device indicating a first air dryer cartridge is installed on an air dryer base and removing the first air dryer cartridge from the air dryer base. The method continues with receiving a second signal from the state change device; attaching a second air dryer cartridge to the air dryer base and receiving a third signal from the state change device indicating the second air dryer cartridge is installed on the air dryer base.
In the accompanying drawings which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the embodiments of this invention.
The air dryer assembly 10 includes an air dryer base 14 for receiving the air dryer cartridge 12. The air dryer cartridge 12 is removably attached to the air dryer base 14 by threads or other means of fastening. An air tight seal will exist between the air dryer cartridge 12 and the air dryer base 14 when the air dryer cartridge 12 is installed on the air dryer base 14. Compressed air enters the air dryer base 14 and passes through the air dryer cartridge 12 to remove moisture and other contaminants. The clean, dry air then exits the air dryer base 14 for use by the air brake system.
The air dryer assembly 10 includes a state change device 16. The state change device 16 is positioned such that it is between the air dryer cartridge 12 and the air dryer base 14 when the air dryer assembly 10 is in use. The state change device 16 may be affixed to the air dryer base 14 or may be a separable device. The state change device 16 transmits state changes in response to the air dryer cartridge 12 engaging the state change device 16.
The air dryer assembly 10 includes a controller 18. The controller 18 may be mounted on the air dryer base 14 or may be remote from the air dryer base 14. The controller 18 may provide power for the state change device 16. The controller 18 includes a processor with control logic 20 for receiving and transmitting signals. The control logic 20 may include volatile, non-volatile memory, solid state memory, flash memory, random-access memory (RAM), read-only memory (ROM), electronic erasable programmable read-only memory (EEPROM), variants of the foregoing memory types, combinations thereof, and/or any other type(s) of memory suitable for providing the described functionality and/or storing computer-executable instructions for execution by the control logic 20.
The control logic 20 receives information regarding each state change of the state change device 16. The state change device 16 may transmit state changes via a direct connection to the controller 18 or wirelessly. The control logic 20 determines whether an air dryer cartridge 12 is installed on the air dryer base 14 based on the state of the state change device 16. The control logic 20 also determines whether another air dryer cartridge has been installed on the air dryer base 14 by monitoring the change of state of the state change device 16 as will be described.
The control logic 20 may also include a cartridge change counter. The cartridge change counter is incremented each time the state change device 16 changes from a first state to a second state. The control logic 20 may also include a timer for measuring elapsed time between each change of state of the state change device 16.
The control logic 20 may also transmit signals to other devices to indicate the status of the air dryer assembly 10. Other devices on the vehicle may include an indicator lamp 22 or a driver information system 24. The control logic 20 transmits a signal to illuminate the indicator lamp 22 in response to the timer being greater than a predetermined time, for example. When the indicator lamp 22 is on, the driver or mechanic is reminded to change the air dryer cartridge 12.
In one example, the state change device 16 may have multiple states. The state change device 16 will cycle through each of the states each time the air dryer cartridge 12 is removed and replaced with a second air dryer cartridge. The state change device 16 may be a variable resistive device. In a first state, when the air dryer cartridge 12 is attached to the air dryer base 14, the state change device 16 transmits a signal equivalent to the power supplied to the state change device 16. In a second state, when the air dryer cartridge 12 has been removed from the air dryer base 14, the state change device 16 transmits a signal that is a percentage of the power signal.
The state change device 16 may remained powered via the controller 18, even when a vehicle ignition is turned off. However, the state change device 16 does not need constant power in order to indicate a change of state, as will be explained.
Therefore, an apparatus for determining when an air dryer cartridge has been replaced comprises a first air dryer cartridge; an air dryer base for receiving the first air dryer cartridge; and a state change device positioned between the air dryer cartridge and air dryer base. The state change device changes from a first state to a second state in response to the first air dryer cartridge being removably attached to the air dryer base, changes from the second state to a third state in response to the first air dryer cartridge being removed from the air dryer base and changes from the third state to the first state in response to a second air dryer cartridge being removably attached to the air dryer base.
The state change device 16′ is shown in its depressed, or second state, indicating that the air dryer cartridge 12 is installed on the air dryer base 14. The state change device 16′ will physically change position from a depressed state to an extended state when the air dryer cartridge 12 has been removed from the air dryer base 14. The state change device 16′ will change from the extended state, or first state, to the depressed state, or second state when the air dryer cartridge 12 is installed on the air dryer base 14.
In this example, a circumferential protrusion 34 on the air dryer cartridge 12 is present. The protrusion 34 will maintain the state change device 16′ in the depressed position when the air dryer cartridge 12 is installed on the air dryer base 14. When the air dryer cartridge 12 is removed, the state change device 16′ is biased to the released position. The location of the state change device 16′ on the air dryer base 14 may be such that if the protrusion 34 is not present on the air dryer cartridge 12, then the state change device 16′ may not be depressed even if the air dryer cartridge 12 is installed on the air dryer base 14.
The state change device 16″ is in position 1-2, or its second state, when the air dryer cartridge 12 is installed on the air dryer base. In position 1-2, the switching device 16 receives power from Vsup such that Vout is approximately equal to Vsup. In this configuration, the state change device 16″ cycles through three states.
The state change device 16″ moves to position 1-3 when the air dryer cartridge 12 is removed from the air dryer base 14, or its first state. In position 1-3, Vout is less than Vsup due to the resistor divider circuit formed by R1 and R3. When a new air dryer cartridge is installed on the air dryer base 14, the state change device 16″ cycles to position 1-4. Vout is less than Vsup due to the resistor divider circuit formed by R2 and R3. The state change device 16″ will then continue to cycle through these positions as air dryer cartridges are removed and replaced on the air dryer base 14.
Vout is read by the controller 18 and is indicative of the state of the state change device 16″. The control logic 20 can then determine from the differences Vout that the position of the state change device 16″ has changed. When the state change device 16″ changes from position 1-2 to position 1-3 then position 1-4, the control logic 20 determines that the air dryer cartridge 12 has been replaced with a new air dryer cartridge.
The control logic 20 may then send a signal to turn off the indicator lamp 22, which may have been turned on due to the length of time since the last air dryer cartridge replacement. The control logic 20 may also send a signal to the driver indicator unit 24 to indicate the date and time when the air dryer cartridge was replaced.
If the state change device 16 did change state, the cartridge change counter in the control logic 20 is incremented in step 56. The indicator lamp 22 may be turned off in step 58 to indicate that a new cartridge has been installed on the air dryer base. In step 52, the cartridge life timer is reset to begin counting the life of the replacement air dryer cartridge. The cartridge change counter in the control logic 20 is incremented when the replacement air dryer cartridge is installed.
Therefore, a method for determining an air dryer cartridge replacement comprises receiving a first signal from a state change device indicating a first air dryer cartridge is installed on an air dryer base and removing the first air dryer cartridge from the air dryer base. The method continues with receiving a second signal from the state change device; attaching a second air dryer cartridge to the air dryer base and receiving a third signal from the state change device indicating the second air dryer cartridge is installed on the air dryer base.
While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.
