Lubricating apparatus for bearings

An apparatus for automatic lubrication of bearings which apparatus incorporates a feeding device (2, 3) for grease and a valve member (7) intended to be connected to a bearing housing. In the valve member (4) is provided at a heat activated member (5) for sensing the bearing housing temperature and which, when a predetermined activation temperature is exceeded, is arranged to expand and to cause a restriction of the lubricant feed.

FIELD OF THE INVENTION 
The present invention relates to an apparatus for automatic lubrication of 
bearings in which a valve member is connected to a bearing housing. The 
valve member includes a feeding device to transfer grease to the bearing. 
BACKGROUND OF THE INVENTION 
It has long been known that rolling bearings must be lubricated to avoid 
direct metal to metal contact between rolling bodies, bearing rings, and 
retainers and the like. The function of the lubricant is not only to 
prevent wear and avoid metallic contact, but also to prevent corrosion. 
It is most advantageous to use a relatively small quantity of lubricant, in 
which the most advantageous operating temperature for that bearing is 
achieved. This is accomplished by using precisely the minimum amount of 
lubricant necessary for reliable lubrication. On those occasions when the 
lubricant is to provide other functions as well, such as sealing or 
cooling, the amount of lubricant may be greater. 
It is also well known that a lubricant loses its effectiveness over time, 
due to mechanical work on the lubricant as well as due to aging of the 
materials from which it is made. A used and polluted lubricant must be 
replaced and renewed at regular time intervals in order to provide a 
uniform and effective lubrication of the bearing or other mechanical 
device. In many instances, rolling bearings are lubricated with grease 
during the normal service operation of the machine. Grease has a 
particular advantage, when compared to oil, for example, in that it much 
more readily stays in the bearing location, particularly in mechanisms 
including a shaft where the shaft is inclined or is vertical. Grease also 
provides certain corrosion inhibiting properties which are of value. The 
choice of the particular grease formulation depends upon the service 
conditions, which are themselves governed primarily by the temperature 
range, the speed of operation, and the environment in which the bearing is 
operating. 
In some circumstances, the service conditions require frequent follow on 
lubrication of the device. Thus bearing housing may, be provided with a 
particular device such as a bore and nipple to allow grease lubrication. 
When the bearing is under a heavy load, it can be connected to an 
automatic lubrication apparatus which continuously provides lubrication to 
the bearing without the need of supervised or manual work. 
These are many automatic lubricating devices on the market today, operating 
under various different principles. These lubricating devices have serious 
functional deficiencies which prevents them from providing the intended 
lubricating effect. Many times, the prior automatic lubricating devices 
are inferior as an alternative to manual lubrication. Deficiencies occur 
quite frequently when excessive grease is fed into the bearing, causing a 
serious increase in bearing temperature, along with the resultant extra 
wear and other difficulties. Bearing life is reduced at these higher 
temperatures. 
Some automatic lubricating apparatus will fail to lubricate or provide 
lubrication on an irregular basis. In this circumstance, the devices fail 
to provide a regular and continuous lubrication which is of extreme 
importance in demanding applications, such as bearings operating at high 
speeds and loads. Under these circumstances, rapid changes in operating 
conditions are magnified and the bearing life is again substantially 
reduced. 
Automatic lubricating devices function basically by feeding the grease to 
the bearing in a variety of ways. Most common are those which utilize 
spring biased pistons and those having an electrolytically general driving 
gas, which acts upon a diaphram connected to a piston. 
One method for controlling the amount of oil lubrication to a lubricating 
device is to adjust the oil supply continuously using heat activatable 
elements. As an example of such a device, French Patent No. FR-A-877500 
shows an oil supply that is normally controlled in such a manner that the 
oil quantity supplied increases at increasing temperature in the device 
being lubricated. This is not an adequate solution for a grease 
lubrication design, however, since an increase in temperature causing an 
increase of grease lubrication to the bearing would result in an increased 
temperature of the bearing housing. 
Accordingly, it is an object of the present invention to provide a new type 
of lubricating apparatus for automatic and controlled supply of a 
lubricating grease to rolling bearings which are mounted in bearing 
housings. 
SUMMARY OF THE INVENTION 
It has now been discovered that the above and other objects of the present 
invention can be accomplished in the following manner. Specifically, a 
device has been discovered in which a continuous lubrication of a rolling 
bearing takes place when the bearing is within an operation temperature 
interval or range. When the bearing housing temperature increases due to 
excessive lubrication, the lubricating grease supply is automatically 
interrupted. 
Specifically, an apparatus has been discovered for automatically 
lubricating a bearing. A feeding device is provided for grease and a valve 
member is connected to a bearing housing. The valve member includes a 
generally tubular valve body and a heat activatable member comprising a 
member metal spring which engages one end of the body. The spring senses 
the temperature of the bearing housing and expands when a certain 
predetermined activation temperature is exceeded. At this point, the 
supply of grease is interrupted, so that the bearing returns to its normal 
operating range.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in the drawing, there is a grease injector which employs a 
cylinder 1 having a movable piston 2 contained inside. Grease is contained 
as shown in the cylinder 1 under pressure from the piston 2 and is moved 
to lubricate the bearing, by force from spring 3 acting on piston 2. 
Grease is transferred from the cylinder and piston arrangement, 1, 2, to 
the bearing 13 housing 14. The transfer is accomplished using a tubular 
valve body 4 which is clamped between two springs 5 and 6. The valve body 
4 is movable in a vertical direction in housing 7 in a manner such that 
the upper portion of valve body 4 covers outlet openings 8 in the valve 
housing 7 when the body 4 is raised. Outlet openings 8 communicate with 
the interior of the cylinder 1 and piston 2 which contains the grease to 
be supplied to the bearing. 
The lower spring 5 is known as a memory metal spring. That is, spring 5 is 
a coil spring made from a memory metal, comprised of metal alloys which 
are activated at a certain temperature. When an activating temperature is 
reached, the spring, when shaped as a coil spring as shown in the FIGURE, 
may double in its length. The spring is reversible, so that it will resume 
its initial length when the temperature is lowered below that activation 
temperature. Memory metal coil springs are available commercially and are 
normally manufactured from metal alloys such as titanium nickel and copper 
zinc aluminum alloys. 
To balance the memory metal spring 5, an upper spring 6 provides a counter 
force. In this manner, a very narrow temperature interval for the 
activating temperature is provided. The upper spring 6 is clamped between 
the valve body such that a nut 9 is threaded upon the valve housing 7. 
This nut may be adjusted by means of a grip 10 which extends out through 
the cover 11 of the cylinder 1. Use of adjustment bar 12 allows the nut 9 
to be adjusted to provide precisely that amount of counterforce against 
which the memory metal spring 5 is acting. 
The lower part of the valve housing 7, which surrounds the memory metal 
spring 5, extends into the bearing housing 14 and is secured thereto by 
conventional means, which are not shown herein. The spring 5 is balanced 
against the spring 6 so that the memory metal spring 5 is in its 
compressed position during normal operating conditions in the bearing 
housing 14. This is the condition shown in the FIGURE, wherein the valve 
is opened and grease flows through the opening 8 into the bearing 13. The 
bearing 13 operates at a conventional temperature and the valve is opened, 
feeding grease continuously into the bearing housing 14. 
If an excessive amount of lubricant is introduced into the bearing housing 
14 the bearing housing 14 temperature will increase. When a predetermined 
activation temperature is exceeded, such as by way of example 60.degree. 
C., the memory metal spring 5 will expand, pushing the tubular valve body 
4 against counterbiasing spring 6. When this happens, the valve body 4 is 
lifted into the valve housing 7 in the direction away from the bearing 13 
itself. The valve body 4 covers the openings 8, thereby cutting off the 
flow of grease into the bearing housing 14. When the temperature drops 
below the activation temperature, the spring 5 will resume its initial 
compressed position. The counterbalancing force of spring 6 will assist 
the return of spring 5 to its compressed position. When this happens, of 
course, the valve body 4 no longer covers openings 8 and the valve is once 
again opened. 
In a number of experiments, tests have shown that a lubricating apparatus 
of the type described above can be provided where the apparatus has an 
on-off function with respect to the supply of grease. In this manner, it 
is possible to limit the bearing housing temperature to a predetermined 
temperature of say, for example, 60.degree. C., for up to about ninety 
(90%) percent of the time the bearing is in operation. It is only during 
the comparatively short period of time when the flow of grease to the 
bearing causes the temperature to peak that the temperature exceeds this 
predetermined temperature. In comparison, the conventional automatic 
lubricating devices which are currently available allow the bearing 
housing temperature to reach the higher temperatures and remain there for 
much longer periods of time. In that circumstance, additional wear of the 
parts is experienced. More important, at the higher operating 
temperatures, the effectiveness and life of the grease decreases rapidly 
and the aging process is accelerated. 
While particular embodiments of the present invention have been illustrated 
and described herein, it is not intended to limit the invention and 
changes and modifications may be made therein within the scope of the 
following claims.