High pressure spray gun

A high pressure spray gun for airless atomization of spray material comprising a safety head mounted on the spray nozzle. The safety head is formed with two parallel protector studs comprising two opposed ridges located transversely to the spray direction and forming a transverse gap through which the spray material has to pass. The ridges are each defined by one flat forwardly inclined surface on each stud and by a common cylindrical surface which forms a transverse part-cylindrical chamber in the safety head. The ridges are formed with opposed edges and prevent spray material from setting on the projector studs.

BACKGROUND OF THE INVENTION 
This invention relates to an airless high pressure spray gun. 
In particular, the present invention relates to a high pressure spray gun 
of the type having safety means for avoiding accidental physical contact 
between parts of the human body and the unatomized part of the spray jet 
adjacent the spray nozzle opening. 
The unatomized part of a spray jet discharged at high pressure is very 
dangerous because of its ability to penetrate human skin and flesh and, 
therby, cause severe injury to, for instance, the user of the spray gun. 
By providing the spray gun with safety means in the form of forwardly 
extending protector studs, accidental contact with the unatomized part of 
the spray jet is avoided. 
A spray nozzle provided with such protector studs is shown in U.S. Pat. No. 
3,556,411. However, the safety means of the disclosed spray nozzle is 
disadvantageous in that the protector studs thereof easily get covered 
with spray material and that the operation of the gun thereby is impaired. 
The object of the present invention is to create a safe high pressure spray 
gun provided with protector studs which are prevented from being hit by 
the spray material. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an airless high pressure spray 
gun comprises a gun body; a spray material valve disposed in the gun body; 
a spray forming nozzle having a geometric axis; and a safety head coupled 
to the nozzle and including two protector studs extending in the spraying 
direction from the nozzle. The protector studs extend respectively on each 
side of the geometric axis of the nozzle, each of the protector studs 
comprising a transverse ridge which is spaced transversely from the 
geometric axis and which is axially spaced from the nozzle in the spraying 
direction, the ridges being disposed out of reach of the spray jet formed 
by the nozzle and the ridges each being arranged in an opposed 
relationship to an identical ridge of the other of the protector studs. 
The protector studs, between the ridges and the spray forming nozzle, 
together form an open ended part-cylindrical chamber, the geometric axis 
of which is substantially perpendicular to the geometric axis of the spray 
forming nozzle, the part-cylindrical chamber extending to the vicinity of 
the spray opening of the nozzle.

DETAILED DESCRIPTION 
The spray gun shown on the drawing comprises a gun body 10 supporting a 
spray material valve 11, a spray forming nozzle 12 including a discharge 
opening 13 and a safety head 14. The spray gun further comprises a handle 
15, a nipple 16 for connecting the spray gun to a spray material pressure 
source and a trigger lever 17 for operating the spray material valve 11. 
The spray material valve 11 comprises a seat 18 rigidly mounted in a valve 
socket 19 and a movable valve body 20. The latter is connected to a 
maneuver rod 21 by means of a coupling sleeve 22. The maneuver rod 21 is 
coupled to the trigger lever 17 via a non-disclosed mechanism. 
At the forward end of the valve socket 19, there is mounted one or more 
transverse deflector pins 24 the object of which is to prevent a solid 
high energy jet from being ejected from the gun when the spray nozzle 12 
is removed. Preferably, the deflector pins 24 are two in number and 
disposed in a parallel relationship to each other. 
The nozzle 12 is clamped against the forward end of the valve socket 19, by 
means of a retaining sleeve 25. The latter is threaded onto the forward 
end of the gun body 10 and has a hexagonal rear portion 26 to be engaged 
by a spanner. 
The forward part 27 of the retaining sleeve 25 is cylindrical and arranged 
to receive thereon the safety head 14. The latter comprises a rear 
cylindrical socket portion 28 to be fitted onto the forward part 27 of the 
retaining sleeve 25. The safety head 14 further comprises two protector 
studs 29, 30 extending in the spray direction on opposite sides of the 
geometric axis 31 of the discharge opening 13 of the nozzle 12. The 
protector studs 29,30 are intended to prevent the operator or any other 
person present during spraying from getting into physical contact with the 
ejected spray material too close to the discharge opening 13, i.e. before 
spray material has become atomized. 
The forward part 27 of the retaining sleeve 25 is provided with an annular, 
wedge shaped shoulder 32 which together with an annular groove 33 in the 
safety head 14 forms a snap coupling for retaining the latter on the spray 
gun. 
Axially spaced from the spray nozzle 12, the protector studs 29,30 are 
formed with transverse, inwardly directed ridges 34,35. The ridges 34, 35 
are defined by inclined surfaces meeting in edges 36, 37 at the top of the 
ridges. The inclined surfaces are constituted on one hand by an inner 
cylindrical surface 38, the axis of which extends transversely through the 
safety head 14, and on the other hand by two forwardly facing, flat 
surfaces 39,40 one on each stud. The cylindrical surface 38 defines a 
transverse, part cylindrical chamber 41. 
The safety head according to the invention is very advantageous from the 
aerodynamic point of view, because the air flow generated by the ejected 
spray material is led through the safety head in such a way as to keep the 
spray material out of contact with the protector studs. 
In the shown embodiment of the invention, the inclined surfaces of the 
ridges 34, 35 have equal angles of inclination in the vicinity of the 
edges 36,37. These angles are illustrated by the letter .alpha. in FIG. 2. 
Between the opposite edges 36, 37, there is formed a transverse gap through 
which the ejected spray material has to pass when leaving the gun.