Method of making a vent valve

A vent valve for a thermostatic valve of a coolant circuit of an internal combustion engine has a ball with a radius and a diameter and serving as a sealing element, and a one-piece metal cage for the ball. The cage has a pot-shaped part with an inside diameter larger than the diameter of the ball, and a bottom having a valve opening surrounded by an outwardly projecting neck. The cage is shaped in one piece from an originally flat metal sheet by stamping, deep-drawing, and pressing, and the pot-shaped part has a height approximately the radius of the ball, and an edge abutted by a plurality of uniformly distributed tabs located on an axial extension of the pot-shaped part, the tabs having inwardly bent ends to retain the ball in the cage with play, the length of the tabs being greater than or equal to the height of the pot-shaped part.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a vent valve for a thermostatic valve of a 
coolant circuit of an internal combustion engine, with a cage made of one 
piece of metal, and a ball serving as the sealing element. The cage has a 
pot-shaped part with an inside diameter larger than the diameter of the 
ball. The bottom of the part is provided with a vent opening surrounded by 
an outwardly projecting neck, whose edge is abutted by retaining means 
retaining the ball with play. 
U.S. Pat. No. 4,059,881 shows a vent valve of the above-described general 
type in which the pot-shaped fitting has a height roughly corresponding to 
the diameter of the ball. The edge of the pot-shaped insert whose inside 
diameter is approximately twice the diameter of the ball is abutted by an 
initially axially directed tab which is later bent inward at a distance 
from the bottom of the pot-shaped part which roughly corresponds to one 
and one-half times the diameter of the ball. It is not disclosed in U.S. 
Pat. No. 4,059,881 how the cage is made. However it can be assumed that 
the cage is made from a section of tubing constructed in the vicinity of 
the neck or expanded in the area of the pot-shaped part. 
It is also known from German Patent DE 81 02 817.2 U1 that a one-piece cage 
can be manufactured by machining. The pot-shaped part of this cage has a 
height which is more than twice the diameter of the ball. After the ball 
is inserted, the edge of the pot-shaped part is pressed inward so that an 
opening remains whose diameter is less than the diameter of the ball. In 
addition, the cylindrical walls of the pot-shaped part are provided with 
transverse bores. 
Vent valves of the initially described general type are used in large 
numbers. An object of the present invention is to provide a vent valve of 
the general type whose manufacture allows mass production at low cost. 
This and other objects are achieved by the present invention by making the 
cage in one piece from an originally flat metal sheet by stamping, 
deep-drawing, and pressing, with a pot-shaped part with a height roughly 
corresponding to the radius of the ball, and with an edge abutted by a 
plurality of tabs uniformly distributed in the axial direction of the 
pot-shaped part and provided with inwardly bent ends, the length of which 
corresponds at least to the height of the pot-shaped part. 
The tabs which are later bent and raised make it possible to hold the cage 
securely in tools during manufacture of the pot-shaped part and the neck 
so that the entire cage can be manufactured in simple fashion by stamping, 
deep-drawing, and pressing. 
In certain embodiments of the invention, the transition between the bottom 
of the pot-shaped part and the neck is in the form of a frustroconical 
valve surface. This valve surface, which ensures the necessary tightness, 
can be produced in simple fashion by a pressing process, this process 
being combined with another work step. 
Other objects, advantages and novel features of the present invention will 
become apparent from the following detailed description of the invention 
when considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
The vent valve shown in the drawings is made as a one-piece metal part from 
an originally flat sheet, especially from a deep-drawable sheet of brass. 
A suitable material for example is a sheet with the material designation 
CuZn37F29, with a thickness of 0.5 mm. The vent valve shown in its 
finished state in FIGS. 1 and 2 has a pot-shaped part (10) whose bottom is 
provided with a valve opening (11). The valve opening (11) is surrounded 
by a neck (12) projecting outward from the bottom. The inside diameter of 
neck (12) is about two-thirds of the diameter of a ball (13) forming a 
sealing element. The neck (12) is pierced for installation by a bore of a 
valve seat of a thermostatic valve and riveted as is known for example 
from German Patent Document DE 81 02 817.2 U1. Valve opening (11) is 
frustroconical, i.e. milled at an angle of 45.degree.. 
The pot-shaped part (10) has an inside diameter which is approximately 
four-thirds of the outside diameter of the ball (13). Four tabs (14) abut 
the pot-shaped part (10), which are raised in the finished state so that 
they constitute an axial extension of the pot-shaped part (10). The ends 
(15) of the tabs (14) are bent inward in such a fashion that they form an 
inside cross section smaller than the diameter of ball (13). The height of 
the pot-shaped part (10) roughly corresponds to the radius of ball (13). 
The axial length of the bent tabs (14) roughly corresponds to the diameter 
of the ball (13), so that a free overall height inside the cage comprising 
the pot-shaped part (10) and the tabs (14) is approximately 1.5 times that 
of ball (13). 
The cage can be manufactured simply and largely automatically by stamping, 
deep-drawing, and pressing, with the ball (13) also being inserted during 
these work steps. Manufacture advantageously is conducted from a sheet 
strip cycled successively through the individual machining stations. 
Initially a blank is punched out of the sheet strip, which remains 
connected by at least two ribs with the sheet strip. This blank comprises 
a middle part widened in one plane corresponding to pot-shaped part (10) 
and the tabs (14) abutting it and still lying in the plane. This blank, 
which is advantageously still connected with the sheet strip, can then be 
held securely by tabs (14) during the next deep-drawing steps in which the 
pot-shaped part (10) and the neck (12) are formed, in such fashion that 
reliable shaping is possible by deep drawing. 
The blank is drawn for example in three deep-drawing steps to a depth which 
corresponds to the height of pot-shaped part (10) and approximately the 
height of neck (12). Then the blank is knocked out to produce the final 
shapes of the pot-shaped part (10) and the neck (12), recessed inward with 
respect to it. The neck (12), which at this time still has a bottom, is 
then perforated and opened. During perforation or even during the opening, 
the frustroconical valve seat can be pressed at the same time. The 
component can still be held by the tabs during these work steps. 
In a next step, the ends (15) of the tabs (14), which initially still lie 
in the plane of the sheet strip, are tilted upward. The ball (13) is then 
placed in the pot-shaped part (10). The tabs (14) are then raised so that 
they come to rest as an extension of the pot-shaped part (10). The last 
step is the cutting free of the cage by severing the connections between 
the cage and the sheet strip still existing with the sheet strip. The vent 
valve is now ready for installation. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.