Patent Application
20080136357
The present disclosure relates generally to reversing an air flow direction of a cooling fan to clear debris caught on an intake screen of a machine, and more particularly to locking out the air intake screen purge cycle when a person may be near the intake screen.
Many types of machines use an engine for motive power, and rely upon a radiator and an air circulation fan to assist in cooling the engine. The engine, radiator and fan are typically positioned within a housing that includes an air intake screen and an outlet opening. During normal operations, the fan draws air into the housing through the air intake screen, directs the air through the radiator and out of the housing through the outlet opening. In many types of applications, the machine may be working or traveling in a dirt and/or debris filled environment. As a result, materials such as dirt, insects, trash, leaves and the like can become lodged on the air intake screen. As material accumulates on the air intake screen, the effectiveness of the air circulation system, and hence the cooling capability of the associated radiator can be undermined.
One strategy for dealing with the accumulation of material on the radiator and air intake screen is taught in co-owned U.S. Pat. No. 6,750,623, which is entitled Reversible Automatic Fan Control System. In that reference, a fan control system periodically and automatically reverses the direction of the air flow system to dislodge accumulated materials from the radiator and air intake screen. After a brief purge cycle, the system automatically returns to its normal cooling operation and again reverses the air flow direction into its normal direction to circulate air from the air intake screen through the radiator and out of the outlet opening. While such an automated air circulation/purge cycle system can normally operate very effectively, and relieve an operator of manually monitoring and operating the fan in a purge cycle, the automated fan reversal system purging cycle can sometimes occur at an inopportune time.
Typically, the air circulation system will continue in its normal mode for some fixed duration, such as thirty (30) minutes, and then be followed by a brief purge cycle on the order of maybe thirty (30) seconds or less. This air circulation/purge cycling continues while the engine of the machine is running. In some instances, it may not be desirable for the purge cycle to occur, such as when a person may be in the vicinity of the air intake screen. In some machines, such as large landfill compactors and wheel loaders, the access path to the operator station actually crosses in front of the air intake screen. In other instances, a service point associated with the machine may be located in the vicinity of the air intake screen. Therefore, persons on an access path or at the service point could have debris blown onto them if the fan reverses direction to initiate a purge cycle.
The present disclosure is directed to one or more of the problems set forth above.
In one aspect, a machine includes an air circulation system supported on a chassis, and includes a fan operably positioned between an air intake screen and an outlet opening of a housing. The fan has a first operation configuration operable to move air from the air intake screen and then out of the housing through the outlet opening, and a second operation configuration operable to move air through the air intake screen in a direction opposite to the first operation configuration. A controller is in control communication with the fan and configured to operate the fan in one of the first operation configuration and second operation configuration. The controller is also configured to lock out the second operation configuration when the machine is idle stationary.
In another aspect, an air circulation system fan is operated in a first operation configuration to move air from an air intake screen then out of the housing through an outlet opening. Debris is removed from the air intake screen by operating the fan in a second operation configuration that moves air through the air intake screen in a direction opposite to the first operation configuration. The second operation configuration is locked out when the machine is idle stationary.
Referring to
This air flow direction reversal or purging cycle can facilitate dislodging material from radiator 23, and accumulated debris on air intake screen 22. The present disclosure contemplates cooling systems having a fan that reverses its rotation direction to facilitate the purging cycle, and also fans that continue to rotate in a single direction but include blades 28 whose pitch orientation is changed in order to reverse the air flow direction through housing 21. Machine 10 may include an access path 31 that passes in front of air intake screen 22. Also, machine 10 may include a service point 33, of a type well known in the art that may also be positioned adjacent air intake screen 22. During a purge cycle, purge material 50 may be dislodged and ejected from air intake screen 22 across access path 31 and/or in the vicinity of a service point 33. If a person were servicing machine 10 or was boarding or unboarding machine 10 via access path 31, the purged material 50 could literally be blown into their face. This type of undesirable event is most likely to occur when machine 10 is idle stationary.
By idle stationary, the present disclosure means that the machine is not moving and any implement is idle. Controller 40 may be configured to determine an idle stationary condition in a number of different ways. For instance, an idle stationary condition may be determined by controller 40 determining that transmission 18 is in neutral gear via communication line 44 and that the machine is not moving. Alternatively or in addition, an idle stationary condition might also be determined by detecting that parking brake 19 is engaged via a communication line 45. If the machine includes an implement, such as a bucket or blade, determination of an idle stationary condition might also require a determination that the implement is idle or not in use. In still another alternative, some machines are equipped with operator presence sensors, such as a seat switch in operation station 30, that a controller may utilize to determine whether an operator is in operator station 30. If an engine of the machine is running, but no operator is detected in the operator station, controller 40 might also determine that the machine is in an idle stationary condition. Those skilled in the art will appreciate that any combination and other known strategies may also be utilized by a controller to ascertain whether the machine is in an idle stationary condition, and hence that a person may be in the vicinity of the air intake screen.
A controller is configured to lock out the fan reversing purge cycle when the machine is in idle stationary condition. However, if a purge cycle has already been initiated before the machine arrives at an idle stationary condition, the controller may opt to complete the purge cycle before initiating a lock out of the purge cycle. In addition, the controller may be configured to maintain the lock out for some duration of time after an idle stationary condition has ended.
The machine may also include a manual means for initiating the fan reversing purge cycle. For instance, machine 10 may include a manual fan configuration switch 41 in communication with controller 40 via a communication line 42. This capability may give an operator the ability to initiate a fan reversing purge cycle at any time as circumstances may demand and for a duration determined by the operator, or for an automatic duration once the switch 41 is activated. In any event, fan 25 is controlled in its operation, whether in its first configuration circulating air in a normal cooling fashion, or in its reversed second configuration to facilitate a purging cycle, via commands generated by controller 40 and communicated to fan 25 via communication line 46. Those skilled in the art will appreciate that controller 40 may actually be two or more controllers that may or may not communicate with one another, but perform the tasks described herein to operate the machine 10 in accord with the present disclosure.
Referring now to
Although this disclosure illustrates a landfill compactor and a large wheel loader, those skilled in the will appreciate that other machines may fall within the scope of the present disclosure. For instance, some large off road trucks include access paths to the operator station that pass directly in front of a radiator grill. In those instances, it would undesirable for any air circulation fan to reverse the air flow direction in a purge cycle when a person is traversing the access path to the operator station to avoid having dust and debris blown onto them. Those skilled in the art will appreciate that any machine that includes a fan reversal purge cycle capability could fall within the present disclosure, since many machines have service points in the vicinity of an air intake screen even though their access paths to operator stations do not pass in front of the air intake screen. Thus, when the machine's engine is running and the machine is stationary, and there is a possibility of a person being in the vicinity of an air intake screen, such as for servicing, the present disclosure would lock out the purging cycle while the machine is in an idle stationary condition.
The present disclosure finds potential application to any machine having an air circulation fan that includes a purge cycling capability that reverses air flow direction to remove accumulated debris from an air intake screen. This includes, but is not limited to, fans that actually reverse there rotational direction to accomplish the purge cycle, and also fans that continue to rotate in the same direction, but change blade pitch orientation to reverse air flow direction. Some examples of potential machines for which this invention could find potential application include machines such as landfill compactors, large wheel loaders, track type tractors, and possibly large off road trucks that include an access path to an operator station or a service point that passes in front of an air intake screen. In addition, the present disclosure finds potential application in any machine that may include a service point in the vicinity of an air intake screen, and such machines could include but are not limited to forestry machinery, track type tractors, excavators, motor graders, scrapers, or any other machine that may operate in a dirt and/or debris filled environment that is subject to having the air intake screen clogged with material needing periodic removal. Those skilled in the art will appreciate that in addition to having a fan reversing air flow purge cycle, the air circulation system would also inherently include a normal operation configuration in which air is circulated from the air intake screen through the housing of the machine and out of an outlet opening.
Referring now to
If the manual switch configuration is on, the software proceeds to query 67 where it determines whether the machine is in a idle stationary condition. In the example software shown, this is accomplished by determining whether the parking brake is engaged. If the parking brake is engaged when the manual switch is activated, the software returns and cycles back to the manual switch query. Thus, an operator using the software flow diagram shown, can not put the machine in an idle stationary condition by engaging the parking brake, and then manually activate the reverse cycle fan switch. If the parking brake is not engaged, the fan reverse status is changed to on, and the controller communicates to the fan to initiate its reverse cycling. Depending upon the fan construction, this might be accomplished by first slowing the fan and then reversing its rotation direction, or may be accomplished by activating actuators to alter the pitch orientation of the fan blades to reverse the air flow direction.
At step 71, the timer is again initialized to zero for the purge cycle duration Z, which may be on the order of several seconds, such as thirty seconds. At query 72, the controller determines whether the timer has exceeded the purge cycle duration Z. If not, the timer is incremented and the fan reversing cycle continues, and the timer is re-queried until the duration has exceeded the purging cycle duration Z. When this is done, the fan reverse cycle is ended at step 74 and the software loops back to reinitialize timer at step 65 to return the fan to its normal air circulation cooling mode.
If the manual switch is off, but the normal cycle timer has exceeded the cooling cycle duration X at query 68, the software again loops toward query 67 where the controller determines whether the machine is in an idle stationary condition. If not, the fan reversing cycle proceeds as shown in steps 70-74 as previously discussed. If the machine is determined to be in an idle stationary condition, the software loops back to the manual switch query. It is expected that software having logic like that shown in Flow Diagram 60 will be continuously running when the fan is being operated to have a normal cooling cycle to circulate air across an engine and/or radiator. Those skilled in the art will appreciate that if the fan is not being used in a normal air circulation cycle, then there will likely be little or no debris accumulating on the air intake screen, and therefore, no purge cycling may be necessary.
Automatic fan air flow direction reversal reduces the need for an operator to stop the machine and manually clean the air intake screen. This allows the operator to stay more focused and productive in carrying out tasks, such as compacting or loading, with the machine. Although automatic air flow reversing to a large extent relieves the operator of this cleaning task, the present disclosure teaches a process by which the air flow reversing purge cycle can be avoided when a person is likely in the vicinity of the air intake screen. Those skilled in the art will appreciate that a wide variety of means can be utilized to determine whether a person is likely near the machine such that the purge cycle should be locked out. Experience has shown that these circumstances arise most often when the machine is idle stationary. Thus, the present disclosure relieves an operator of continuously monitoring and cleaning the air intake, and does so in a way that reduces the likelihood that debris dislodged from the air intake screen will be blown onto a person, such as the operator, who is servicing the machine or mounting or dismounting the same.
It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present invention in any way. Thus, those skilled in the art will appreciate that other aspects of the invention can be obtained from a study of the drawings, the disclosure and the appended claims.
