Lubricating device

Details Lubricating device Lubricating device

2002-09-18

2004-10-12

Bucci, David A. (Department: 3682)

Lubrication

Lubricators

Force feed

C184S037000, C184S105100, C074S001500

Reexamination Certificate

active

06802394

ABSTRACT:

TECHNICAL FIELD
This invention relates to a lubricating device for automatically delivering lubricant, such as grease or oil, over an extended period of time, the lubricating device being of the kind comprising cylinder means having front wall means with a discharge outlet, rear wall means and cylindrical side walls, piston means movable within the cylinder means from a rear position to a forward position, the piston means and the side and front wall means of the cylinder means defining a variable volume chamber for containing the lubricant to be dispensed, helical spring means movable from a compressed condition to an expanded condition to release spring force for moving the piston means from its rear position towards its front position to reduce the volume of the said variable volume chamber over a period of time for expelling lubricant through the discharge outlet, and control means for controlling the movement of said spring means from its compressed condition to its expanded position and comprising an escapement mechanism, electrical means controlling the operation of the escapement mechanism and gearing connected between said escapement mechanism and said piston means
BACKGROUND OF THE INVENTION
Dispensing devices for lubricants of the kind generally known as self-contained automatic lubricators were introduced almost 40 years ago and have now become widely used for dispensing lubricants into lubricant channels of machine bearings over prolonged periods of time, for example from between 1 and 12 month. Such self-contained devices are supplied to users ready-filled with lubricant for fitting temporarily to the bearings they are intended to lubricate. They are designed to lubricate for a predetermined period without further attention on the part of the user. Once that period is over and the lubricant contents have been spent, the entire lubricator is removed and replaced with another. Self-contained automatic lubricators are particularly advantageous for the lubrication of scattered and isolated bearings, such as exist, for example, in water treatment works, dockyards, traffic barriers and countless other applications. Millions of self-contained automatic lubricators are now used annually world-wide and they are steadily replacing older methods of lubricating bearings involving labour intensive replenishment of lubricant by the frequent application of hand-operated grease guns. As self-contained automatic lubricators are normally screwed directly into grease nipple sockets and are frequently required to be fitted in confined spaces, they are designed to be very compact and as light in weight as possible. The great majority of such lubricators are designed to dispense between 100 ml and 120 ml of lubricant. They typically exert pressures of about 0.5 bar or more when injecting lubricant into bearings offering no resistance to flow but are capable of exerting pressures up to 5 bar when necessary to overcome resistance to flow in the bearing. Typically, this requires the lubricators to apply forces varying from 100 N up to 1000 N in order to move pistons in lubricant chambers of from 50 to 60 mm in diameter.
Self-contained automatic lubricators of this type are relatively inexpensive and are quite different from more complicated centralised lubrication systems such as are designed for lubricating all the bearings of, for example, a single large machine inside a factory building, which are designed to be permanent fixtures, which require high operating pressures and which are bulky, heavy and expensive.
Self-contained automatic lubricators are not to be confused with some earlier types of single-point lubricator that were designed to be fixed permanently to a single bearing for refilling in-situ and which were much heavier, bulkier and more expensive. A known lubricating device of the kind referred to is described in U.S. Pat. No. 1,929,774. This device is an early type of “permanent” lubricator designed to be repeatedly filled in situ—i.e. it is not a so-called self-contained automatic lubricator of the type described above. It is supplied with electricity from an external supply and, consequently, is not self-contained. It is also relatively bulky and heavy with the escapement mechanism and associated gearing being positioned axially behind the helical spring means resulting in the lubricating device being relatively long in the axial direction.
Other known single-point lubricators that antedate self-contained automatic lubricators as described hereinbefore have spring means consisting of helical compression springs but are designed to be permanent fixtures and, unlike self-contained automatic lubricators, require frequent replenishment by means of hand-operated grease guns. On actuation of the lubricator, the energy from the spring is released to urge the piston device to move towards its forward position thereby expelling the lubricant. The helical compression spring is thus the only force generating means acting on the piston to expel the lubricant. Although the rate at which the lubricant is discharged can be influenced by substituting springs with different characteristics, by valving or by varying the discharge orifice, the actual rate of discharge of such a device on a particular bearing is governed primarily by the resistance in the bearing channels, the fluidity of the lubricant, and the ambient temperature (which affects the fluidity of the lubricant). Although such a known lubricator can be made relatively inexpensively, it does not have the facility to preset or predetermine a rate of lubricant discharge that is independent of the variable factors mentioned above. Furthermore for certain applications and operating conditions the lubricator will dispense all its lubricant within a few weeks of initiating the lubricant dispensing process.
In order to overcome the disadvantages of the known single-point lubricators, self-contained automatic lubricators have been designed in which the spring means have been replaced by actuating means which can be controlled to vary the rate of lubricant discharge in a controlled manner. In such self-contained automatic lubricators, the piston device separates the cylinder into a variable volume first chamber containing the lubricant to be dispensed and a second chamber. The second chamber contains an electrolyte into which a galvanic element comprising different metallic materials that are connected together electrically to form electrodes can be introduced from a third chamber. The resultant electro-chemical reaction gradually generates gas which moves the piston device to discharge the lubricant content. Lubricators of this type can be set to discharge over periods as long as 12 months at rates that can be predicted with limited accuracy. They have the disadvantage that the electrochemical reaction is very sensitive to changes in ambient temperature and it is necessary for users to consult tables to determine the approximate discharge rate and operating duration at specific ambient temperatures (which in working conditions can vary from as low as −20° C. to as high as +55° C.). Examples of such lubricators are described in GB-A-1,401,535 and U.S. Pat. No. 3,430,731.
Another known self-contained automatic lubricator is described in EP-A-0278138 and has a chamber containing an electrolyte together with electric batteries which enable an electric current to be passed through the electrolyte to generate gas, together with electric or electronic control means for switching on or off and/or varying the current flow and hence the rate of gas generation and the rate of discharge of lubricant. The discharge rates of such lubricators can be predicted with limited accuracy and they can operate for long durations, but they have the disadvantages that they require a relatively large battery pack to maintain the electrochemical reaction over long periods, the electrochemical reactions are temperature sensitive and the lubricators are relatively expensive.
It is also known from German G9214096.3 for a self-contained automatic lubrica

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