Spray apparatus

Abstract

 Spray apparatus fo carrier-less high pressure spraying of materials, for example mortar, comprising a pump housing (31) having an inlet (9) for the material with an associated non-return valve (13), and having an outlet (11) for the material with an associated counter-placed non-return valve (23), and pressure means (41) generating alternately pressure and suction for pressurizing and feeding the material. The spray apparatus further comprises a mobile piston (43), which is placed under a determined but adjustable counter-pressure, so that when a pre-selected pressure has been generated in the pump housing (3) this pressure will be maintained at a constant level by displacing the mobile piston (45) outwardly so as to increase the dead volume (51) of the pump housing.

Description

[0001] The present invention relates to a spray apparatus for the high pressure spraying of materials of different types, for example sand mortar, without supplying a carrier medium, for example air.

[0002] Spraying apparatuses of this type are previously known. Thus, there is described in Swedish patent 7216089-8 an arrangement in spray apparatuses for high pressure spray­ing, wherein the problem of releasing the pressure from the pump is solved by the use of an arrangement, where the piston stroke of the pump is automatically adjusted in relation to the flow outlet. This known apparatus is associated with drawbacks, among which there may be mentioned high production cost and non-acceptable operational reliability.

[0003] The object of the present invention is to eliminate the drawbacks associated with the prior art and to provide a spray apparatus which can be manufactured at a substantially lower cost and, in addition, has a high degree of safe opera­tion and reliability.

[0004] For this object the spray apparatus according to the invention comprises a pump housing having an inlet for the material with an associated non-return valve, and having an outlet for the material with an associated non-return valve which is placed in opposite direction in relation to the first-mentioned non-return valve. Said apparatus further com­prises pressure means which alternately generates pressure and suction and which provides for pressurizing and feeding out of the material. The spray apparatus is characterized by a mobile piston which is placed under a determined but adjus­table counter-pressure so that when a pre-selected pressure has been generated in the pump housing this pressure will be maintained at a constant level by displacing the mobile pis­ton outwardly so as to increase the dead volume of the pump housing thereby limiting the pressure increase to the desired level.

[0005] In a preferred embodiment of the spray apparatus ac­cording to the invention said pressure means is constituted by a reciprocating press piston. This press piston is impar­ted a reciprocating movement in a conventional manner, for example by using excentric, piston rod, cam control or the like.

[0006] The counterpressure applied to the mobile piston and variable as desired can be generated in several ways. Thus, the counter-pressure can be generated for example by using a spring subjected to a variable adjustable pre-tension. In an alternative embodiment the mobile piston can be controlled through a pressure medium contained in a pressure accumulator acting on the exterior of the mobile piston for providing the desired counterpressure.

[0007] In a particular embodiment of the invention the pump housing is designed as a circular cylindric elongate body, wherein the pressure means is arranged at one end thereof and the mobile piston at the other end thereof. At about the mid­point of said body the inlet and the outlet are arranged op­posite to each other and containing the oppositely placed non-return valves. The spray apparatus according to the in­vention can be designed in many different ways as long as the basic concept of the invention is maintained, namely the fea­ture that when the material of the pump housing has reached a certain pressure the dead volume of the pump housing is chan­ged by the mobile piston being displaced outwardly against the pre-set counter-pressure. In this manner the pressure in the spray apparatus will be maintained constant at varying supplied quantities of material.

[0008] The invention will in the following be further descri­bed by a specific embodiment in the form of a high pressure pump for sand mortar. This description is made in connection with the appended drawing which diagramatically and in an elongate section shows an embodiment of the spray apparatus according to the present invention.

[0009] The spray apparatus shown in the drawing and generally designated 1 in principal comprises an elongate circular cy­lindric pump housing 3 harbouring a reciprocating press pis­ton 33 and a mobile piston 43 at the other end of pump hou­sing 3. At its midpoint pump housing 3 is provided with coun­ter-positioned valve housings 5,7 provided with inlets 9 and outlets 11 for the material to be treated. In connection with the inlet 9 valve housing 5 is provided with a non-return valve 13 having a valve head 15, as spindle 17, a valve seat 19 and a compression spring 21. This non-return valve 13 al­lows inlet of sand mortar through openings 9 but prevents the sand mortar from leaving the interior of pump housing 3 through the inlets 9.

[0010] At the opposite side of pump housing 3 valve housing 7 with the outlet 11 is arranged. This valve housing 7 is also provided with a non-return valve 23 having a valve head 25, a spindle 27, a seat 29 and a compression spring 31. This non-­return valve 23 allows outlet of sand mortar through opening 11 but prevents sand mortar from being transported back into the interior of pump housing 3.

[0011] Press piston 33 is provided with a piston rod 35 hav­ing a sealing 37 at the passage through the end wall of pump housing 3. Furthermore, it is provided with a sealing piston ring 39. Press piston 33 is imparted a reciprocating movement by a conventional excentric device designated 41, which can for example be constituted by a piston rod.

[0012] The mobile piston 43 is affected from the outside by a pressure medium 45 with associated pressure accumulator 49 and a hand pump 47 for generating the desired pressure of pressure medium 45.

[0013] The function of the device described above is briefly as follows. Using the hand pump 47 the pressure medium 45 is given the desired pressure so that the mobile pistion 43 is affected from the outside of this pre-determined pressure. By the reciprocating movement of press piston 33 sand mortar is supplied through openings 9 and fed into the interior space 51 of pump housing 3 and is then fed out as a result of the progressively increasing pressure in pump housing 3 through the outlet 11 to the desired location for its use. When the pressure by the reciprocating movement of press piston 33 has reached a certain predetermined value the dead volume of pump housing 3 will be increased by the mobile piston 43 being displaced outwardly a distance against the counterpressure of pressure medium 45. In this manner a substantially constant pressure will be maintained inside pump housing 3 at varying consumption of sand mortar.

[0014] The device for providing counter-pressure on the mobi­le piston 43 may, instead of the described embodiment, be constituted by a compression spring of variably adjustable counter-pressure.

[0015] The apparatus described above is of simple construc­tion, is reliable in the operation and can be manufactured at low cost.

[0016] Even if a specific embodiment has been described above it is obvious to the skilled artisan that the spray apparatus described can be modified in many ways within the scope of the appended patent claims.

Claims

1. Spray apparatus fo carrier-less high pressure spraying of materials, for example mortar, comprising a pump housing (31) having an inlet (9) for the material with an associated non-return valve (13), and having an outlet (11) for the material with an associated counter-placed non-return valve (23), and pressure means (41) generating alternately pressure and suction for pressurizing and feeding the materi­al, characterized by a mobile piston (43) which is placed under a determined but adjustable counter-pressure, so that when a pre-selected pressure has been generated in the pump housing (3) this pressure will be maintained at a constant level by displacing the mobile piston (45) outwardly so as to increase the dead volume (51) of the pump housing.

2. Spray apparatus according to claim 1, characterized in that said pressure means is constituted by a reciprocating press piston (33).

3. Spray apparatus according to claim 1 or 2, charac­terized by a spring of variable adjustable pre-tension provi­ding counter-pressure on the mobile piston (43) from the out­side.

4. Spray apparatus according to claim 1 or 2, charac­terized by a pressure accumulator (49) containing a pressure medium (45) acting on the exterior side of the mobile piston (43) for providing the desired counter-pressure.

5. Spray apparatus according to any preceding claim, characterized in that the pump housing (3) is designed as a circular cylindric elongate body with counter-placed pressure means (33) and mobile piston (43), respectively, and that the inlet (9) and the outlet (11) are arranged therebetween and are oppositely placed.

Drawing