Mixer unit with thermostat-controlled valves

A mixer unit with thermostat controlled valves for mixing hot and cold liquid includes a housing with valves for supplying the hot and cold liquid to the housing. The housing includes a mixing chamber which terminates in a discharge spout. A yoke is rockably mounted in the housing and the ends are arranged to make contact with and actuate the valves for the hot and cold liquid. A bimetallic spiral control thermostat is carried in the discharge spout and cooperates with the yoke for causing rocking movement of the yoke when the thermostat spirally moves in response to regulation of the thermostat. A device is carried at the outer end of the discharge spout for adjusting the position of the spiral of the thermostat about its axis of symmetry and thereby regulating the desired temperature of the mixed liquid.

BACKGROUND OF THE INVENTION 
This invention relates to a mixer unit in which the opening relationship 
between valves for cold and hot liquid respectively is regulated by a 
bimetal spiral which causes rocking movement of a yoke to actuate the 
valves. 
Thermostat-controlled mixer units of various kinds, usually for water, are 
previously known. There are in existence mixer valves with bellow 
thermostats, with thermostats of bimetal strips and with sleeve-shaped 
thermostats made of materials having a coefficient of expansion different 
to that of the surrounding mixer housing. 
Known thermostatic mixers are as a rule relatively large owing to the fact 
that the actual thermostats must be of a certain length in order to be 
capable of moving by an amount necessary to adjust the valves within the 
temperature range concerned. 
SUMMARY OF THE INVENTION 
The purpose of this invention is to enable the production of a mixer unit 
with good temperature stability in the mixed medium within a range 
embraced by that of conventional hand-operated mixer valves. In order to 
achieve this purpose, the thermostat employed is designed as a double 
spiral made of two noncorroding metals placed in the discharge spout of 
the mixer unit. Hereby the spiral continuously senses the temperature of 
the mixed liquid, and, since the two metals in the spiral have different 
longitudinal coefficients of expansion, the spiral tends to open or unwind 
as the temperature increases and to close or wind up as the temperature 
decreases. Fixed to the inner end of the spiral is a yoke which rocks with 
the turning motion of the spiral, the opposite ends of this yoke moving 
pistons towards their closed position in the valves for hot and cold 
liquid respectively. At the outer end of the spiral located in the 
discharge spout a device is arranged for adjusting the position of the 
spiral about its axis of symmetry and thereby regulating the desired 
temperature of the mixed liquid. Flow control for the mixer is 
accomplished by means of a knob fixed to a rising spindle passing through 
and emerging from the upper section of the mixer housing. By adjusting 
this knob the position of the spindle is changed and with it the height of 
a ball stud at its lower end. The above-mentioned yoke rocks on this ball 
stud and as the height of the yoke above the valve increases, greater 
movement above the seats of the pistons in the valve acting as cones is 
permitted, whereby an increasing flow through the mixer is obtained. 
The pistons, which are free to move in the cylindrical valves are drilled 
out centrally and so shaped that their movements are facilitated by servo 
forces attained. The aforementioned drilled holes continue through 
constrictions in the crowns of the pistons. The ends of the yoke, which 
rest against the crowns of the pistons when the valves are closed, are 
provided with rubber inserts at their points of contact with the valves to 
ensure a good seal against the holes in the piston crowns.

DESCRIPTION OF THE INVENTION 
With reference to the accompanying drawings, the mixer unit illustrated 
consists of a mixer housing 1 with a discharge spout 2. Situated in 
discharge spout 2 is a bimetal spiral 3 acting as a thermostat. This is 
constructed in a known manner from two spiralized flat wires bonded 
together, one of which in principle forms a spiral inside a spiral formed 
by the other. The former preferably has a greater longitudinal coefficient 
of expansion than the latter, whereby the end of the bimetal spiral 3 
situated furthest out in the discharge spout 2 is fixed, the spiral 
rotates about its own axis of symmetry. Thereby the angle of rotation of a 
point on the spiral increases the further inwards in the discharge spout 2 
this point is situated. A yoke 4 is attached to the inner end of the 
bimetal spiral 3. This yoke is rocked by the reciprocating rotary motion 
of the bimetal spiral. A ball stud 5 serves as a pivot point for the yoke 
4. This ball stud consists of the lower end of a rising spindle 6 passing 
through the upper section of the mixer housing 1 and provided for control 
with a knob or the like which is not shown. By turning this control knob 
the spindle 6 is raised or lowered and with it the ball stud 5. In this 
way the flow through the mixer is regulated. 
The yoke 4 actuates valves 7, 8 for hot and cold water respectively. These 
are of identical construction and consist of cylinders 9 in which pistons 
10 can move. U-packings or cup packings 11, 12 are located between the 
cylinder walls and the pistons for sealing purposes, whereby the upper 
packings 12 are inverted in relation to the lower packings 11. Ring-shaped 
cavities 13 are thereby formed in the valves. Through narrow holes 14 
arranged radially in the pistons 10, these cavities are in connection with 
the central axial drillings 15 in the pistons. From existing holes 16 in 
the lower ends of the pistons 10 which are of substantially smaller 
diameter than the drillings 15, the connection leads out into inlet ducts 
17, 18 for hot and cold water respectively. 
Operation of the mixer is such that water from the inlet ducts 17, 18 
enters the cavities 13 where mains pressure prevails in the state of rest. 
When the spindle 6 is rotated by means of the control knob that is not 
shown, the spindle rises and with it the ball stud 5. This gives the yoke 
4 a certain clearance and its ends, which are provided with rubber inserts 
19 for sealing against the hemi-spherical crowns of the pistons 10, lift 
away from the piston crowns, thus exposing existing holes 20 which 
communicate with the drillings 15. The water pressure in the cavities 13 
rapidly diminishes as water passes from them to the radial holes 14 in the 
pistons 10 and into the drillings 15 and from there through the holes 20 
in the piston crowns and out into the mixer housing 1. The pressure in the 
inlet ducts 17, 18 then presses up the pistons 10 acting as valve cones 
from their seats 21. Since the pistons 10 are provided with machined 
grooves 22 in which the lower cup packings 11 of the valves 7, 8 are 
located, these packings accompany the pistons on their upward movement. 
Thereby outlet openings 23 in the walls of the valve cylinders 9 are 
exposed and hot or cold water respectively can pass into the mixer housing 
1 and on to the discharge spout 2. 
The bimetal spiral 3 situated in the discharge spout 2 senses the 
temperature of the mixed water. The positional locking device for the 
outer end of the bimetal spiral 3 is designed to permit adjustment of the 
desired temperature of the mixed water. For this purpose the spiral is 
fitted with a fork-shaped endpiece 24 in which a stud 25 with a ball shape 
is located. This stud 25 forms an obtuse angle with the axis of symmetry 
of the bimetal spiral 3 in a neutral position, i.e. the setting for 
hand-warm water. Stud 25 is connected with a ring 26 consisting of two 
concentric sections. This ring acts as a temperature setting device and on 
turning it the angle between the stud 25 and the axis of symmetry of the 
bimetal spiral 3 is changed. The bimetal spiral is thereby turned by its 
fork-shaped end section 24. The spiral then senses the temperature of the 
mixed water and regulates the opening relationship between the valves 7, 8 
for hot and cold water respectively in the matter described above. 
To shut off the flow through the mixer spindle 6 is turned by means of the 
control knob not shown. The ball stud 5 is thereby lowered and the yoke 4 
consequently presses down against the crowns of pistons 10 of the valves 
7, 8. The rubber inserts 19 in the ends of the yoke 4 then block the holes 
20 in the piston crowns. This has the effect of closing the slight flow 
which passes through the pistons the whole time when the valve is open and 
the volume of which is determined by the holes 16, preferably in nipples 
27, in the lower ends of the pistons 10. When this flow has been shut off 
the pressure inside the drillings 15 in the pistons 10 rapidly builds up 
and through the radial holes 14 the pressure in the cavities 13 will 
attain the same level as that in the inlet lines 17, 18. Since the same 
pressure will prevail on both sides of the lower cup packings 11, a very 
slight force, exercised by the yoke 4, is required to close the valves. In 
consequence, it is here a matter of servo-assisted shut-off-valves for hot 
and cold water respectively. 
If regulation of the opening relationship between the valves should require 
more force on larger mixers, several bimetal spirals can be mounted and 
connected in parallel with each other. In other respects, several of the 
other components can be modified within the concept of the invention as it 
is defined in the following claims.