Patent Application
20170051763
The present disclosure is generally directed to a machine and, more particularly, to operation of a hydraulic accessory in the machine.
Large machines, such as, but not limited to hauling or dump trucks used in mining operations, are mechanically complex and may be costly to operate. Such a machine often is exposed to high shock and vibration which may also reduce the serviceable lifetime of various parts. One such part is an air conditioning compressor that is mechanically coupled to an internal combustion engine and driven by gears off a flywheel or related engine part. As a result of this mechanical attachment, the air conditioning compressor may be subjected to higher than desirable vibration originating in the engine, which in turn may reduce the service life of the air conditioning compressor.
Further, in order to reduce fuel consumption and its associated cost, newer machines are automatically reducing engine power or even turning the engine completely off when the machine is not traveling. For example, the engine may be shut off while waiting to load or unload, during loading, idling, or other downtime. While this can result in significant savings, for example, of as much as 450 gallons of fuel per year per machine, a side effect is that certain accessories, including the air conditioner, are not available during these periods. Depending on the environment and season, this may cause an operator unwelcomed discomfort.
With respect to machine air conditioning compressors, U.S. Pat. No. 8,909,431, issued Dec. 9, 2013 to Kooi (the '431 patent), discloses calculating a load on an internal combustion engine including the load demand from an air conditioning compressor and adjusting a power output of the engine accordingly. However, among other things, the '431 patent fails to address providing cooling during intermittent periods when the engine is shut down.
In an aspect of the disclosure, a machine includes a power source, a hydraulic pump powered by the power source that provides pressurized hydraulic fluid and an accumulator that stores the pressurized hydraulic fluid provided by the hydraulic pump. The machine also includes an accessory operated via the pressurized hydraulic fluid and a valve that selectively provides the pressurized hydraulic fluid from the accumulator to the accessory to operate the accessory when the hydraulic pump is inactive.
In another aspect of the disclosure, a method of operating a compressor in a machine includes powering a hydraulic pump using a power source of the machine, the hydraulic pump providing a pressurized hydraulic fluid in a hydraulic circuit and charging an accumulator with the pressurized hydraulic fluid. The method may include sensing that the hydraulic pump is inactive and providing the pressurized hydraulic fluid from the accumulator to an accessory when the hydraulic pump is inactive. The method may conclude by operating the accessory while the hydraulic pump is inactive using the pressurized hydraulic fluid from the accumulator.
In still another aspect of the disclosure, a machine having a power source and a hydraulic pump driven by the power source may include an accumulator that stores a pressurized hydraulic fluid provided by the hydraulic pump and an air conditioning compressor operated via the pressurized hydraulic fluid. The machine may also include a valve that directs the pressurized hydraulic fluid from the accumulator to the air conditioning compressor only when the hydraulic pump is inactive.
These and other aspects and features will be more readily understood when reading the following detailed description when taken in conjunction with the accompanying drawings.
Referring to
As discussed more below, the machine 100 may incorporate a system 102 for operating a hydraulically-driven accessory while the power source 101 of the machine 100 is turned off or operating at an idle speed that is too low to sufficiently power the accessory.
A system 102 for operating an accessory 110 that is hydraulically driven is illustrated in
When the machine is in normal operation, the accumulator 114 may act to even out pressure in the hydraulic circuit 105 by absorbing pressure spikes and may also act to provide pressurized hydraulic fluid during peak loads. In a some embodiments, multiple accumulators may be used in such a hydraulic circuit 105, even though only one accumulator 114 is illustrated in
However, as discussed above, in a current embodiment, the power source 101 may routinely be turned off for short periods during idle conditions to save fuel and to be more ecologically friendly. When this happens, some accessories, especially the air conditioning compressor 106 cease to operate. Depending on conditions, an operator's cab may become uncomfortably hot in a very short time with the air conditioning off Rather than simply draining the accumulator 114 during a short idle period, a valve 120 may be used to allow the pressurized hydraulic fluid 116 in the accumulator 114 to operate the accessory 110, in this example, the air conditioning compressor 106.
The valve 120 may be positioned as a check valve during normal operations, for example, to shield the pump 104 from pressure spikes generated by tools associated with the other hydraulic loads 118. When the pump 104 is off and the pressure at the accumulator side 132 of the valve 120 remains higher than the pressure on the pump side 130 of the valve 120, pilot pressure on the accumulator side 132 of the valve 120 opens the valve 120 and allows free flow of pressurized hydraulic fluid 116 from the accumulator 114 to the accessory 110.
When the pump 104 is off, especially when due to the power source 101 being shut down, the other hydraulic loads 118 are not active. That is, if the machine 100 is idle, such as waiting to be loaded, there is no reason to activate the hydraulic cylinders to lift a bed of the machine 100. Therefore, pressurized hydraulic fluid 116 in the accumulator 114 that would typically be drained can be used to operate the accessory 110 and provide air conditioning to the operator station 103. Note the air conditioning fan is electric and can be operated during these short idle periods by the machine battery.
An orifice 122 may be inserted to limit flow to the accessory 110, or in the case of an adjustable orifice, to adjust the flow to the accessory 110. For example, the orifice 122 may be adjusted based on an output requirement of the air conditioning compressor 106 and a pressure of the pressurized hydraulic fluid 116 at the accumulator 114. In an embodiment, the orifice 122 may be opened further as the pressure from the accumulator 114 drops.
The controller 126 may also directly monitor the pump 104 and/or the power source 101 to make the determination that the pump 104 is inactive and to operate the valve 124.
In general, the present disclosure can find industrial applicability in machines in a number of different settings, such as, but not limited to those use in the earth-moving, construction, mining, agriculture, transportation, forestry, and marine industries.
A flowchart of a method 200 of operating an accessory 110 when a power source 101 of a machine 100 is turned off is shown in
At block 204, pressurized hydraulic fluid may be provided to an accessory 110. As discussed above, the accessory 110 may be any number of devices driven directly or indirectly by pressurized hydraulic fluid.
An accumulator 114 may be charged with the pressurized hydraulic fluid 116 delivered by the hydraulic pump 104 via the hydraulic circuit 105 at block 206. The accumulator 114 may be used to provide a buffer for sudden pressure increases or decreases in the hydraulic circuit 105.
An operating state of the hydraulic pump may be sensed at block 208. Specifically, conditions at the pump 104, the power source 101, or in the hydraulic circuit 105 may be sensed to determine that the pump 104 is inactive. This determination may be made in a number of manners. In an embodiment, a hydraulic pressure at both sides of the valve 120 may compared simply by how a bias of the valve 120 is selected, as shown in the embodiment of
In another embodiment, illustrated, for example, in
If it is determined at block 208 that the pump 104 is active, the “no” branch may be taken to block 204 and the loop continued. If, however, it is determined at block 208 that the pump 104 is inactive, the “yes” branch may be taken from block 208 to block 210. At block 210, a further check may be made to determine if the pressure in the accumulator 114 is above a minimum pressure or if the pressure difference across the valve 120, 124 is above a threshold value. In various embodiments, this may involve a direct measurement or may be part of the process that determines that the pump 104 is inactive. For example, in the embodiment illustrated in
When, at block 210, the pressure is insufficient, the “no” branch may be taken to block 212 and the power source 101 may be restarted with execution then continuing at block 204.
When, at block 210, the pressure in the accumulator 114 is sufficient, the “yes” branch may be taken to block 214 and pressurized hydraulic fluid 116 from the accumulator 114 may be provided to an accessory 110. In an embodiment, activating the valve 120 or 124 may fluidly connect the accumulator 114 to the accessory 110 only when the hydraulic pump 104 is inactive or the pressure at the accumulator 114 is sufficient. In an embodiment, the accessory 110 may be a hydraulic motor 108 that drives an air conditioning compressor 106. In another embodiment, the accessory 110 may be an integrated air conditioning unit having both the hydraulic motor 108 and the air conditioning compressor 106 as a single unit.
Finally, the accessory 110 may be operated at block 216 using the pressurized hydraulic fluid 116 from the accumulator 114 when the hydraulic pump 104 is inactive. In the case where the accessory 110 is an air-conditioning unit, operating the accessory is associated with providing air conditioning to an operator station 103 of the machine 100. Operation at block 212 may continue as long as the pump is inactive or until the accumulator 114 can no longer supply sufficient pressurized hydraulic fluid 116 to operate the accessory.
The ability to use the pressurized fluid from the accumulator 114 to drive an accessory 110, especially an air conditioning compressor 106, when a power source 101 and therefore a hydraulic pump 104 of a machine 100 is off, provides a benefit not only to operators but to owners as well. The immediate benefit to an operator is not having to sit in a hot cab during idle periods. The benefit to an owner is that a more aggressive energy saving policy can be implemented by turning the power source 101 off more frequently under a broader range of conditions without unduly burdening the operator.
The use of a hydraulically-driven compressor 106 over prior art mechanical air conditioning compressors that are gear driven by the power source 101 benefits the owner by reduced downtime and increased service life by moving the accessory 110 away from the high shock and vibration of the power source 101. Further, an operating speed of the accessory 110 can be independently controlled by the flow of pressurized hydraulic fluid 116, where the speed of the prior art mechanical compressor was solely tied to the speed of the power source.
While the above discussion has been directed to a particular type of machine, the techniques described above have application to many other machines.
