Lubrication – Systems – With safety or indicating means
Patent
1996-06-12
1998-06-23
Verdier, Christopher
Lubrication
Systems
With safety or indicating means
184 622, 184 624, 184 272, 184 271, 1841041, F16N 740, F16N 2902, F16N 1316
Patent
active
057691827
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a lubricant supply safety system for a machine, comprising a reservoir for lubricating oil, a hydraulic motor driving one or more feeder pumps supplying lubricating oil from said reservoir to various points in said machine, a first pump for supply of lubricating oil from said reservoir to drive said hydraulic motor under normal operating conditions, and a second pump for supply of lubricating oil from said reservoir to drive the hydraulic motor in the event of a failure of said first pump.
Even a very temporary absence of lubricating oil to an expensive piece of machinery can have devastating and expensive consequences. Several methods have therefore been developed to assure that lubricant will continue to be pumped to the machine even in the event of a pump breakdown or a power failure. This is particularly important in machines which require a long time period to stop due to a heavy moving mass or if they must be emptied of material being processed before they can be stopped. Two or more pumps, for example, can be arranged in parallel so that if one pump should fail, the other pump or pumps will continue to at least supply partial oil pressure to the machine. There is a disadvantage, however, that in a system with only two main pumps, the flow delivered in this failure situation will only be 50% of the normal operating pressure. Parallel backup systems have also been used which require mechanisms for the backup pump to kick in in the event of a failure of the normal pump. Such backup systems require that the backup pump be started immediately in the event of a failure of the first pump and that they have a power source, usually an electric motor which is intact and is supplied with electric current. In the event of an electrical power failure, a backup pump powered by an electric motor may be rendered useless. Also, one can never be 100% sure that a backup pump, which only kicks in in the event of a failure of the normal pump, will start running immediately and is in proper functioning order. Frequent tests are required in this case to maintain such backup reliability.
SUMMARY OF THE INVENTION
These disadvantages of the prior art are removed in a lubricant safety system as described by way of introduction which is characterized in that said second pump is continuously driven by said machine and is automatically engaged by means of a valve device to drive said hydraulic pump immediately upon detection of a malfunction of said first pump. A large piece of machinery with a large rotating mass, for example, or which must be emptied before it can be stopped may require a run-down time of 20 minutes more, and if the second pump is continuously driven via a belt whenever the machine is in motion, it will already be in operation when it is needed to supply high pressure oil to the hydraulic motor. Since said second pump is driven continuously, it will in a sense be continuously tested and any malfunctioning thereof can be immediately detected.
According to a preferred embodiment of the lubricant supply safety system according to the invention, the continuously driven second pump is connected via the valve device under normal operating conditions to a low-pressure line returning oil to said reservoir. Since the second pump is under normal operating conditions never loaded to supply high pressure, it will not be subjected to high-pressure stresses and can therefore be operated for very long time periods without any foreseeable problems.
Further advantages can be obtained by including in the low-pressure line an oil filter and an oil cooler. The second pump is therefore made use of during normal operation for the functions of filtering and cooling the oil. According to a further advantageous embodiment of the lubricant supply safety system according to the invention, added reliability is obtained by mechanically biasing the valve to move immediately to the fail-safe position when the first pump fails to deliver pressurized oil. This allows the safety
REFERENCES:
patent: 2416947 (1947-03-01), Palm
patent: 3398688 (1968-08-01), Columbu et al.
patent: 4237993 (1980-12-01), Jablonsky
patent: 4444292 (1984-04-01), Brown et al.
patent: 4976335 (1990-12-01), Cappellato
Kvaerner Hymac Inc.
Verdier Christopher
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