Oil level indicator for an engine with an integral spring for establishment of a calibration position

An oil level indicator assembly for a vehicle engine including an elongated indicator member removably housed in a tubular sleeve which has spaced upper end and lower end portions with an interior passage therebetween and an internal shoulder-like formation therein. The elongated indicator member has a coil spring formation adapted to engage the shoulder-like formation when the indicator and sleeve are in an assembled relationship, thereby establishing a predetermined length of the indicator to project into the engine oil. The effect of oil on indicia formed on the indicator member when withdrawn from the sleeve member shows the level of oil in the engine.

BACKGROUND 
1. Field of the Invention 
The present invention relates generally to an oil level indicator assembly 
for an engine and more particularly for an oil level indicator device 
which includes an axially yieldable portion to accommodate changes in the 
length of the indicator and to establish a calibration position with 
respect to a support housing and to the oil level. 
2. Description of the Related Art 
Vehicle engines typically utilize oil level indicators or "dip sticks" for 
checking the level of oil in the sump portion or oil pan of the engine. 
Normally, this dip stick is inserted into a tube and the effects of 
gravity are relied upon to maintain its rest position in the tube. It is 
desirable to utilize the housing tube both for supporting the dip stick 
and for an inlet passage for introducing oil into the engine. When the 
tubular housing is increased in diameter to allow it to be used for oil 
introduction, it is necessary to provide a combination cap or cover and 
dip stick handle. Thus, the cover or cap becomes fixed to the tubular 
housing. The U.S. Pat. No. 1,658,774 to Taub discloses a combination level 
indicator, oil introduction housing, and cap/handle arrangement, as does 
U.S. Pat. No. 4,640,126 to Jansch. Other relevant U.S. patents include: 
U.S. Pat. No. 2,756,716 to Petrossian; U.S. Pat. No. 2,757,647 to 
Kishline; U.S. Pat. No. 4,055,898 to Braun et al.; U.S. Pat. No. 4,330,940 
to Leitgeb; and U.S. Pat. No. 4,941,268 to Tausk. 
SUMMARY OF THE INVENTION 
The present invention provides an enlarged level indicator housing or 
sleeve so that oil can be introduced into the oil sump portion of the 
engine. The elongated level indicator has an upper combination cover or 
cap for the sleeve and handle for the indicator member. The lower portion 
of the sleeve and the indicator have cooperative structural features to 
establish a calibration support for the indicator with respect to the 
sleeve. This calibration support is close to the oil level in the engine 
so as to provide a relatively short lower portion of the indicator member 
between the calibration support and the oil level so that any effects of 
growth or shrinkage of the indicator member caused by temperature changes 
is minimized. 
More specifically in a preferred embodiment, the elongated indicator member 
has a yieldable portion integrally formed therein which establishes the 
aforedescribed described calibration support along with a shoulder-like 
structure formed within the sleeve's interior passage. The yieldable 
portion is preferably in the form of a compressible coil spring having an 
end surface formed by the lowest coil which surface abuts the 
shoulder-like portion. This forms a generally circular ring located in a 
plane normal to the axis of the indicator member. 
Other objects, features and advantages of the present invention will become 
apparent by reference to the following detailed description when 
considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 1, a cross-sectioned elevational end view of an internal combustion 
engine 10 is shown. Engine 10 is composed of an engine block 12 having 
cylinder bores 14 formed therein (only one shown). A piston 16 is shown 
reciprocally mounted in bore 14. Piston 16 is pivotally connected to an 
upper end of a connecting rod 18 whose lower end portion is attached to a 
journal 20' of a crankshaft 20. The block 12 is cooled by coolant flow 
through passages 22 formed in the block. 
A cylinder head assembly 24 overlies and is attached to the upper end of 
the block 12. The cylinder head assembly 24 overlies each of the cylinder 
bores 14 and with surface 16' of a piston 16 a combustion chamber 26 is 
formed. A spark plug 28 is associated with each combustion chamber to 
cause a mixture of air and fuel to burn in the combustion chamber 26 when 
the plug is energized. Air and fuel enter the combustion chamber 26 
through an intake passage 30 in the cylinder head and the flow is 
regulated by opening and closing of an intake valve (not visible in FIG. 
1). After burning and expanding in the combustion chamber 26, the gases 
formed from the air and fuel passes from the combustion chamber 26 through 
an exhaust passage 32. Flow into the exhaust passage 32 is regulated by 
opening and closing of an exhaust valve 34 (shown in an opened position). 
The exhaust valve 34 seats against a valve seat 36 when in its closed 
operative position. As is true with the intake valve, the exhaust valve 34 
is moved from a closed position to its opened position (shown) against the 
force of a closing spring 38 by the action of a clockwise pivoting 
actuator or rocker arm 40. The rocker arm 40 is pivoted in response to the 
passing engagement of a lobe portion 42 on a rotating camshaft 44. A 
roller 46 carried by the end of the rocker arm reduces friction between it 
and the lobe 42. 
Other known engine components in FIG. 1 include an intake manifold 48, 
passages 50 in manifold 48, and intermediate passages 52 in an air 
distributing connecting member 54. Also, an electrically actuated fuel 
injector 56 is shown. 
The bottom portion of the block 12 must be open during engine assembly to 
facilitate the mounting of pistons 16 in bores 14 and the installation of 
the crankshaft 20. Once these components are assembled into the block, the 
bottom portion is enclosed by an oil pan member 58 which is attached to 
the block by a plurality of fasteners (not shown) along its edges 58'. The 
oil pan 58 is utilized to define an oil storage sump or enclosure 60 into 
which a desired quantity of lubricating and cooling oil 62 is contained. 
The desired quantity of oil defines a liquid surface 64 in the sump 60. 
During engine operation, the level of oil in the sump decreases due to 
pumping of the oil to bearings, etc. However, a minimum level of oil is 
always desirable in the sump 60 so that the inlet of the oil pump (not 
shown) is always able to take in oil. 
As seen in FIG. 1 but even better shown in FIG. 2, an oil level indicating 
assembly 66 is utilized for allowing a vehicle owner or service mechanic 
to check the level (quantity) of oil in the engine and more exactly, the 
level in the sump of an inoperative engine. The oil level indicating 
assembly 66 includes an elongated, tubular sleeve member 68 defining an 
interior passage 70. The sleeve member 68 has an open upper end portion 
68' and a lower end portion 68". The lower end portion 68" has a reduced 
outer diameter portion 72 for insertive mounting in an aperture 74 formed 
in a wall portion 76 of the block 12. The aperture 74 has radially 
inwardly directed splines or tabs 78 which are received by correspondingly 
formed grooves 80 in the lower end portion 68" of the sleeve. Interaction 
of the tabs 78 with the grooves 80 prevents rotation of the sleeve in the 
aperture 74. An O-ring seal 82 between the end portion 68" and the wall 
portion 76 inhibits oil leakage therebetween. Finally, insertion of the 
sleeve 66 into aperture 74 is limited by engagement between a radially 
outwardly directed lip 84 and the surface 86 of a boss 88. The whole 
sleeve assembly is secured relative to the engine by attachment of a 
flange portion 90 to an upper portion of the engine which also prevents 
upward movement of the sleeve out of aperture 74. In addition, the grooves 
80 may include circumferentially extending portions to permit a limited 
partial rotation of the sleeve 68 in the aperture once it is fully 
inserted. This would establish the sleeve in a locked condition both in 
the rotative sense and also in an axial manner to prevent outward movement 
of the sleeve from the aperture 74 of the engine block 12. 
The oil level indicator itself is an elongated, cylindrical member 92 which 
has a slender and somewhat flexible mid portion 94. The upper end portion 
92' of the member 92 is attached to a radially extending cap member 96. 
The cap portion is adapted to attach to or be secured with respect to the 
upper end portion of the sleeve to fix the member 92 at an axial position 
with respect to the sleeve member 68 when in a usual storage position 
during which the engine is operated and the oil level is not being 
checked. The indicator member 92 has a lower end portion 98 which extends 
from the lower end portion 68" and wall portion 76 into the sump enclosure 
60 and into the quantity of oil 62 therein, especially when the engine is 
inoperative as seen in FIG. 1. At the desired liquid level 64 for the oil 
in the sump 60, the surface of the indicator is scribed or otherwise 
marked to form indicators or indicia 100. In a preferred embodiment, this 
indicia 100 is in the form of scribed or raised lines to indicate a 
desired or maximum level, an "add oil" level, and cross-like formations or 
roughness therebetween. This allows an observer to readily observe where 
the upper surface 64 of the oil has contacted the indicator member 92. 
It can be seen that the relative axial position of the indicator member 92 
with respect to the supporting sleeve member is very important for 
accurate reading of the oil level 64 in the sump enclosure 60. It can be 
understood that inaccuracies in the axial positioning of member 92 with 
respect to sleeve 68 also effects accuracy. Significantly, temperature 
changes of the indicator member 92 are a source of inaccuracy. Since 
indicator member 92 is elongated, it is subject to substantial axial 
growth with changes in temperature. The subject indicator provides an 
improved accuracy in level detection by providing a solid support for the 
lower portion of the indicator member 92. This support is located very 
near the oil level 64 to minimize the length of the indicator which can 
change with temperature variations. 
Specifically, the lower end portion of the sleeve member 68 has a reduced 
diameter bore 102 which forms a continuation of the larger diameter 
interior passage 70. The reduction of the interior diameter forms a 
shoulder-like formation or circular edge 104. 
The indicator member 68 has a helically shaped coil spring portion 106 
integrally formed adjacent the shoulder-like formation 104. Specifically, 
the coil spring portion 106 has a portion 108 which forms a substantially 
circular ring positioned in a plane normal to the axis of the indicator 
member 92. Accordingly, when the indicator member 92 is inserted into the 
sleeve 68 and cap portion 96 is secured to the sleeve, this circular ring 
seats against the shoulder-like formation 104 and yielding of the spring 
accommodates any axial variation of the member 92. More importantly, the 
seating of ring 108 against seat 104 establishes a desirable centering of 
the indicator's lower portion 98 and also accurately positions the 
indicator member 92 with respect to the desired liquid level 64. Thus, any 
growth or decrease in the length of the relatively short lower portion 98 
with temperature changes does not result in any significant inaccuracies. 
While the invention has been described in detail, it is to be expressly 
understood that it will be apparent to persons skilled in the relevant art 
that the invention may be modified without departing from the spirit of 
the invention. Various changes of form, design or arrangement may be made 
to the invention without departing from the spirit and scope of the 
invention. Therefore, the above mentioned description is to be considered 
exemplary, rather than limiting, and the true scope of the invention is 
that defined in the following claims.