HVLP-Sprühgerät

Abstract

HVLP spray device (1) with an electric blower (2) comprising a needle valve (3) for metering the paint (F) supplied to an air cap (4), - wherein the needle valve (3) comprises a valve body (6) with an elongated interior (7), a valve needle (8), a compression spring (9) and a seal (10), - wherein the interior (7) between the seal (10) and a nozzle opening (11) of the valve body (6) is designed as a paint chamber (12) into which a supply channel (K) for the paint (F) opens and which is supplied with paint (F) during spray operation of the HVLP spray device (1), characterized in that - that the interior (7) of the valve body (6) between the supply channel (K) and the seal (10) is tapered in such a way, - that a needle guide (13) is formed and - that the seal (10) is arranged opposite the color space (12) and is adjacent to the needle guide (13).

Description

[0001] The invention relates to an HVLP spray device according to the preamble of claim 1.

[0002] From CN 2 02 174 020 U, an electric spray gun with a valve needle is known, which can be quickly disassembled and washed.

[0003] Furthermore, DE 20 2015 106 132 U1 discloses a paint spraying device for generating a paint spray pattern, which comprises a paint nozzle positioned in a gap, wherein the paint nozzle comprises a needle with a needle head deviating from a rotationally symmetrical cross-sectional design and a paint outlet opening deviating from a rotationally symmetrical cross-sectional design, wherein the needle head is displaceable relative to the paint outlet opening on a longitudinal axis of the needle for controlling a needle valve formed from the paint outlet opening and the needle head, wherein the needle head, in a closed position of the paint nozzle, positively closes the paint outlet opening with respect to the longitudinal axis, and wherein the needle head and / or the paint outlet opening is / are formed by a material with elastic properties, at least in a surface area with which the two components contact each other.

[0004] The object of the invention is to propose an HVLP spray device in which the replacement and / or cleaning of the valve needle and / or the seal is not only easy to carry out, but in which the sealing of the valve needle can also be easily and quickly restored to a high quality.

[0005] This problem is solved by means of the characterizing features of claim 1, starting from the features of the preamble of claim 1. Advantageous and expedient embodiments are specified in the dependent claims.

[0006] The HVLP spray gun with an electric blower includes a needle valve for metering the paint supplied to an air cap. The needle valve comprises a valve body with an elongated interior, a valve needle, a compression spring, and a seal. The interior space between the seal and a nozzle opening of the valve body is designed as a paint chamber, into which a supply channel for the paint opens. During spray operation of the HVLP spray gun, the paint flows through this chamber. The interior of the valve body is tapered between the supply channel and the seal to form a needle guide, and the seal is positioned opposite the paint chamber, resting against the needle guide. A defined interaction between the seal and the needle guide allows the seal to be mounted precisely within the interior of the valve body and thus reproducibly positioned relative to the valve needle.

[0007] According to the invention, the valve body is designed with a circumferential collar in its interior to form the needle guide. Such a collar can be easily manufactured using injection molding and can also be easily installed as a component.

[0008] It is also provided that the valve body is designed with a circumferential flange to form the needle guide, the flange being shaped like a pipe end on an end face of the collar, with the end face facing away from the color chamber. With such a needle guide, a functionally predefined interaction with the seal is possible.

[0009] Furthermore, the needle guide is designed to form a ring-shaped, circumferential recess. This prevents the seal from being installed in a twisted position.

[0010] It is also intended to position the seal between a locking element and the needle guide and to compress the seal between the locking element and the needle guide. This securely holds the seal in its intended position and reliably prevents the seal from moving away from the flange when the needle is retracted.

[0011] Furthermore, it is provided that the locking element is supported on an inner surface of the valve body's interior, wherein the support is achieved in particular by positive locking, and wherein the locking element is screwed into the valve body, and wherein it is preferably provided that the inner surface of the interior behind the needle guide has an internal thread and that the locking element has an external thread matching the internal thread. Such support is reliable and also allows the use of seals of different lengths, so that a variety of seals can be used as replacement parts, thus simplifying the procurement of spare parts.

[0012] It is also provided that the valve body is designed in multiple parts, wherein the valve body comprises a front sub-housing which carries the air cap with the nozzle opening and, in particular, also includes the needle guide, and wherein the valve body comprises a rear sub-housing in which, in particular, the compression spring is housed, wherein the two sub-housings are axially separable from one another such that, after removal of the rear sub-housing with the seal installed, the valve needle can be pulled out of the front sub-housing, and wherein the two sub-housings are, in particular, screwed together. Such a valve body allows for both quick disassembly and quick assembly. Due to the interaction of the rear sub-housing with the front sub-housing with the compression spring positioned between them, the assembly can also be checked by the counter-pressure that builds up during screwing together due to the compression spring.

[0013] Furthermore, the seal is designed in the manner of a shaft seal with a circumferential groove, wherein the groove opens towards one of two end faces of the seal and wherein the end faces lie between an inner and an outer contact surface of the seal. Such a seal is available as a standard component and is suitable for use with the needle guide.

[0014] It is also possible to position the seal with an outer rib in the annular recess of the needle guide, the outer rib of the seal being formed between its circumferential groove and its outer contact surface, and to position the seal with an inner rib between the needle guide and a cylindrical surface of the valve needle, the inner rib of the seal being formed between its circumferential groove and its inner contact surface. This allows for a reliable seal to be achieved through simple axial assembly.

[0015] Furthermore, the valve needle is supported against an end of the valve body opposite the nozzle opening by means of an interposed compression spring. This ensures that the nozzle opening is reliably closed when a trigger actuating the needle is not engaged.

[0016] It is also intended that the locking element be screwed into the valve body against the seal with a torque between 0.75 Nm and 2 Nm. Such a torque range is generally achieved even without a torque wrench if the included socket wrench specifies that the locking element should be tightened to medium-tight to full torque. Therefore, the locking element is tightened correctly even without the use of a torque wrench. This reduces effort and simplifies the process.

[0017] Furthermore, it is planned to design the inner surface of the needle guide tube end in such a way that the inner surface of the tube end approaches the valve needle circumferentially towards the color chamber. Due to this inclined surface, the inner web of the seal is guided against the needle's surface when the locking element is tightened, thus achieving an increasingly tight seal.

[0018] It is also provided that the inner surface of the pipe end is at an angle α to a longitudinal axis of the valve needle, wherein a circumferential contact surface formed on the inner web of the seal towards the groove of the seal is at an angle β to the longitudinal axis of the valve needle during assembly of the seal before contact with the inner surface of the pipe end, and wherein the angle β is smaller than the angle α and, in particular, is at most 2 / 3 of the angle β. Such different angles cause the seal to spread out, thereby optimizing its contact with the valve needle.

[0019] Finally, with respect to the longitudinal axis of the valve needle, the seal is in axial and radial contact with the needle guide, and a positive-locking connection between the seal and the needle guide is provided. This ensures a reliable seal, maintaining its sealing effect even if the seal warps, shrinks, or moves due to aging. Furthermore, the seal remains in position for an extended period even if the retaining element should loosen.

[0020] For the purposes of the invention, an HVLP spray device is understood to be a spray device which operates according to the so-called High Volume Low Pressure low-pressure painting process with high air volume and low pressure.

[0021] For the purposes of the invention, the term "paint" also includes other liquid media which behave like paint or similarly to paint when sprayed.

[0022] Further details of the invention are described in the drawing with reference to schematically illustrated embodiments.

[0023] This shows: Fig. 1: a schematic sectional view of an HVLP spray device according to the invention, in which cut surfaces are not hatched to maintain clarity; Fig. 2: the one in the Fig. 1 HVLP spray gun shown in perspective exploded view with air cap hidden and paint container unscrewed; Fig. 3: a sectional view of a seal of the HVLP sprayer; Fig. 4: a detailed view of the [item] in the Fig. 1 HVLP spray device shown in the area of ​​a needle guide, with a valve needle and a locking element hidden and the seal to be mounted shown schematically; Fig. 5: one to the Fig. 4 comparable detailed view, showing the valve needle and hiding the locking element and seal.

[0024] In the Fig. Figure 1 shows a schematic sectional view of an HVLP spray device 1 according to the invention, wherein cut surfaces are not hatched to maintain clarity.

[0025] The HVLP spray gun 1 is equipped with an electric blower 2, indicated only schematically by dashed lines, and includes a needle valve 3 for metering the paint F supplied from a paint container 5 to an air cap 4. The needle valve 3 comprises a valve body 6 with an elongated interior 7, a valve needle 8, a compression spring 9, and a seal 10. The valve body 6 is closed by the air cap 4.

[0026] The interior space 7, located between the seal 10 and a nozzle opening 11 of the valve body 6, which is formed in the air cap 4, is configured as a color chamber 12. A supply channel K opens into the color chamber 12, through which the paint F flows from the paint container 5. During spray operation of the HVLP sprayer 1, the paint F flows through the color chamber 12 in a spray direction x.

[0027] The interior 7 of the valve body 6 is tapered between the supply channel K and the seal 10 such that a needle guide 13 is formed. The seal 10 is arranged opposite the color chamber 12 and abuts the needle guide 13.

[0028] The valve body 6 is multi-part and comprises a front sub-housing 14, which includes the needle guide 13, and a rear sub-housing 15, in which the compression spring 9 is housed. The valve body 6 also includes the air cap 4, which closes the front sub-housing 14 and has the nozzle opening 11. The two sub-housings 14 and 15 are axially separable from each other, so that the valve needle 8 can be pulled out of the front sub-housing 14 after removing the rear sub-housing 15 with the seal 10 installed. The two sub-housings 14 and 15 are screwed together. According to embodiments not shown, the two sub-housings may also be connected by means of a bayonet fitting, a plug-in fitting, or at least one clamping lever, allowing them to be detachably and re-closable.

[0029] In the Fig. 2 is the one in the Fig. Figure 1 shows the HVLP spray device 1 incomplete and in a perspective exploded view with the air cap hidden and the paint container unscrewed. This exploded view shows how, during the assembly of the needle valve 3, the seal 10 is first inserted into the front housing 14 of the valve body 6, then the locking element 20 is screwed into the front housing 14, then the valve needle 8 is inserted through the seal 10, then the compression spring 9 is placed onto a free end 8b of the valve needle 8, and finally the rear housing 15, accommodating the compression spring 9 and the free end 8b of the valve needle 8, is screwed onto the front housing 14 until the valve needle 8, with its needle head 8a, closes the nozzle opening formed in the hidden air cap.

[0030] The component in and on which the valve body 6 of the needle valve 3 is received is referred to as the body housing RG of the HVLP spray device 1.

[0031] The Fig. Figure 3 shows the seal 10 of the HVLP sprayer in cross-section.

[0032] The Fig. 4 shows a detailed view of the [item] in the Fig. 1 HVLP spray device 1 shown in the area of ​​the needle guide 13, with the valve needle and the locking element hidden and the seal 10 to be mounted shown schematically.

[0033] The Fig. 5 shows one related to the Fig. 4 comparable detailed view of the HVLP spray device 1, showing the valve needle 8 and hiding the locking element and the seal.

[0034] As can be seen in particular from the enlarged detailed views of the Fig. 4 and Fig. As can be seen in Figure 5, the valve body 6 comprises a circumferential collar 16 in its interior 7 to form the needle guide 13, and the valve body 6 further comprises a circumferential flange 17 to form the needle guide 13. The flange 17 is formed in the shape of a tube end 18 on a rear end face 16b of the collar 16. The rear end face 16b faces away from the color space 12. A front end face 16a of the collar 16 faces the color space 12.

[0035] The needle guide 13 described above forms a ring-shaped circumferential receptacle 19.

[0036] The seal 10 is arranged between a locking element 20 and the needle guide 13 (see Fig. 1), wherein the seal 10 is squeezed between the locking element 20 and the needle guide 13 for the operation of the HVLP spray device 1 (see Fig. 1), so that this seals off an actuation chamber 21 located behind the needle guide 13 in the direction of spraying x, opposite the color chamber 12 around the valve needle 8.

[0037] In order to build up pressure on the seal 10 and against the needle guide 13, the locking element 20 (see Fig. 1) on an inner surface 22 (see in particular Fig. 4 and Fig. 5) the interior 7 of the valve body 6 is supported. This support is achieved by positive locking, with the locking element 20 being screwed into the valve body 6. For this purpose, the inner surface 22 of the interior 7 behind the needle guide 13 has an internal thread 23, and the locking element 20 has an external thread 24 that matches the internal thread 23 (see Fig. 2) on. The locking element 20 has a receptacle 25 for a socket wrench (not shown). The receptacle is formed by four bores, as can be seen from the Fig. 2 is evident. The appropriate socket wrench is then designed, for example, as a tube with four pins arranged at its ends and, with the rear partial housing 15 and compression spring 9 removed, can even be inserted into the color space 12, taking the valve needle 9 into the receptacle 25 of the locking element 20 formed by the four bores, in order to screw it into or unscrew it from the front partial housing 14 of the valve body 6. Of course, a transverse bolt 26 (see Fig. 1, Fig. 2 and Fig. 5), over which the valve needle 8 with a trigger 27 (see Fig. 1 and Fig. 2) of the HVLP spray device 1, is pulled out of the valve needle 8 when the socket wrench not shown is used.

[0038] The seal 10, which is in the Fig. Figure 3, shown in isolation, is designed in the manner of a shaft seal with a circumferential groove 28. The groove 28 opens towards one of two end faces 29, 30 of the seal 10, namely the left end face 29. The end face 29, which is designed similarly to two concentric circular rings, and the end face 30, which is designed similarly to a single circular ring, are formed between an inner contact surface 31 of the seal 10 and an outer contact surface 32 of the seal 10.

[0039] As in the Fig. As indicated by an arrow pointing in the spray direction x, the seal 10 is slid onto the needle guide 13 during assembly with its groove 28 pointing towards the circumferential receptacle 19 of the needle guide 13. The seal 10 engages with an outer web 33 in the annular circumferential receptacle 19 of the needle guide 13, the outer web 33 of the seal 10 being formed between its circumferential groove 28 and its outer contact surface 32. The seal 10 engages with an inner web 34 between the needle guide 13 and a cylindrical surface M8 of the valve needle 8, the inner web 34 of the seal 10 being formed between its circumferential groove 28 and its inner contact surface 31. For a summary of the described process, see the following: Fig. 4 and Fig. 5 referred, since in the Fig. 4. To maintain clarity, the valve needle is hidden. In the Fig. In figure 5, the valve needle 8 is shown, and the seal 10 is hidden. Further reference is made to the... Fig. 1 referred.

[0040] The overall structure of the HVLP spray device 1 is derived from the Fig. 1 can be seen how the valve needle 8 is supported against an end 35 of the valve body 6 or rear sub-housing 15 opposite the nozzle opening 11 by means of the compression spring 9.

[0041] In order to achieve a desired sealing effect and to seal the actuation chamber 21 despite the valve needle 8 moving in the spray direction x or in the opposite spray direction x' when actuated by the trigger 27, the locking element 20 is screwed into the valve body 6 against the seal 10 with a torque which is between 0.75 Nm and 2 Nm.

[0042] As can be seen from the comparative analysis of the Fig. 4 and Fig. As can be seen in Figure 5, an inner surface 36 of the tube end 18 of the needle guide 13 approaches the valve needle 8 towards the color space 12 and forms a truncated conical surface. Accordingly, the inner surface 36 of the tube end 18 is at an angle α to a longitudinal axis L8 of the valve needle 8. A circumferential contact surface 37 formed on the inner web 34 of the seal 10 towards the groove 28 of the seal 10, which is formed by the inner bearing surface 31 of the seal 10, is at an angle β to the longitudinal axis L8 of the valve needle 8 when the seal 10 is assembled and before contact with the inner surface 36 of the tube end 18 (see Figure 5). Fig. 3) Here, the angle β is smaller than the angle α. Sliding the seal 10 onto the needle guide 13 causes the seal 10 to spread open. This allows the inner web 34 to conform particularly well to the outer surface M8 of the valve needle 8.

[0043] The mounted seal 10, clamped by means of the locking element 20, rests against the needle guide 13 both axially x circumferentially and radially y circumferentially and is also positively connected to it (see Fig. 4 and Fig. 1) The groove 28 of the seal 10 sits under pressure on the circumferential receptacle 19 of the needle guide 13 when the seal 10 is fully assembled. Reference symbol list: 1 HVLP sprayer 2 electric blowers 3 needle valve 4 air cap 5 paint containers 6 valve bodies 7 Interior 8 Valve needle 8a Needle head of 8 8b free end of 8 9 compression spring 10 Seal 11 Nozzle opening 12 color space 13 Needle guide 14 front sub-housing of 6 15 rear sub-housing of 6 16 collars 16a front face of 16 16b rear end face of 16 17 flange 18 Pipe ends 19 circumferential recording formed by 13 20 safety element 21 Activity area 22 inner surface area of ​​7 23 internal threads on 22 of 7 24 external threads on 20 25 sockets for 20 socket wrenches 26 cross bolts 27 deduction 28 Nut in 10 29 left frontal side of 10 30 right front of 10 31 internal installation area of ​​10 32 external installation area of ​​10 33 outer bridge of 10 34 inner bridge of 10 35 End of 6 opposite 11 36 inner surface area of ​​18 37 Contact surface at 34 α Angle between 36 and L8 β Angle between L8 and 37 F color K Supply channel L8 Longitudinal axis of 8 M8 surface area of ​​8 RG fuselage casing of 1 x Spray direction / axial direction x' Counter spray direction y radial direction

Claims

[1] HVLP spray device (1) with an electric fan (2) comprising a needle valve (3) for dosing the paint (F) supplied to an air cap (4), - wherein the needle valve (3) comprises a valve body (6) with an elongated interior (7), a valve needle (8), a compression spring (9) and a seal (10), - wherein the interior space (7) between the seal (10) and a nozzle opening (11) of the valve body (6) is designed as a paint space (12) into which a supply channel (K) for the paint (F) opens and through which the paint (F) flows during spraying operation of the HVLP spray device (1), characterized by , - that the interior (7) of the valve body (6) between the supply channel (K) and the seal (10) is tapered in such a way, - that a needle guide (13) is formed and - that the seal (10) is arranged opposite the ink chamber (12) and adjacent to the needle guide (13). [2] HVLP spray device according to claim 1, characterized by that the valve body (6) comprises a circumferential collar (16) in its interior (7) to form the needle guide (13). [3] HVLP spray device according to claim 2, characterized by in that the valve body (6) further comprises a circumferential flange (17) for forming the needle guide (13), wherein the flange (17) is designed in the form of a pipe end (18) on an end face (16b) of the collar (16), wherein the end face (16b) faces away from the color space (12). [4] HVLP spray device according to claim 2 and 3, characterized by that an annular circumferential receptacle (19) is formed by the needle guide (13). [5] HVLP spray device according to at least one of the preceding claims, characterized by , - that the seal (10) is arranged between a securing element (20) and the needle guide (13) and - that the seal (10) is squeezed between the securing element (20) and the needle guide (13). [6] HVLP spray device according to claim 5, characterized by , - that the securing element (20) is supported on an inner surface (22) of the interior (7) of the valve body (6), - wherein the support is effected in particular by form-fitting and wherein the securing element (20) is in particular screwed into the valve body (6) and - wherein it is preferably provided that the inner circumferential surface (22) of the interior (7) behind the needle guide (13) has an internal thread (23) and that the securing element (20) has an external thread (24) matching the internal thread (23). [7] HVLP spray device according to at least one of the preceding claims, characterized by , - that the valve body (6) is constructed in several parts, - wherein the valve body (6) comprises a front housing part (14) which carries the air cap (4) with the nozzle opening (11) and in particular also comprises the needle guide (13) and - wherein the valve body (6) comprises a rear partial housing (15) in which in particular the compression spring (9) is accommodated, - wherein the two partial housings (14, 15) are separable from one another in the axial direction (x') in such a way that the valve needle (8) can be pulled out of the front partial housing (14) after the rear partial housing (15) has been removed with the seal (10) mounted, - wherein the two partial housings (14, 15) are in particular screwed together. [8] HVLP spray device according to at least one of the preceding claims, characterized bythat the seal (10) is designed in the manner of a shaft sealing ring with a circumferential groove (28), wherein the groove (28) opens to one of two end faces (29, 30) of the seal (10), wherein the end faces (29, 30) lie between an inner contact surface (31) of the seal (10) and an outer contact surface (32) of the seal (10). [9] HVLP spray device according to claims 4 and 8, characterized by , - that the seal (10) is seated with an outer web (33) in the annular circumferential receptacle (19) of the needle guide (13), wherein the outer web (33) of the seal (10) is formed between its circumferential groove (28) and its outer contact surface (32), and - that the seal (10) is located with an inner web (34) between the needle guide (13) and a lateral surface (M8) of the valve needle (8), wherein the inner web (34) of the seal (10) is formed between its circumferential groove (28) and its inner contact surface (31). [10] HVLP spray device according to at least one of the preceding claims, characterized by that the valve needle (8) is supported against an end (35) of the valve body (6) opposite the nozzle opening (11) with the compression spring (9) interposed. [11] HVLP spray device according to claim 6, characterized by that the securing element (20) is screwed into the valve body (6) against the seal (10) with a torque of between 0.75 Nm and 2 Nm. [12] HVLP spray device according to at least one of the preceding claims, characterized by that an inner circumferential surface (36) of the tube end (18) of the needle guide (13) is aligned such that the inner circumferential surface (36) of the tube end (18) approaches the valve needle (8) in the direction of the color space (12). [13] HVLP spray device according to claim 12, characterized byin that the inner circumferential surface (36) of the pipe end (18) is at an angle (α) to a longitudinal axis (L8) of the valve needle (8), wherein a circumferential contact surface (37) formed on the inner web (34) of the seal (10) towards the groove (28) of the seal (10) is at an angle (β) to the longitudinal axis (L8) of the valve needle (8) during assembly of the seal (10) before contact with the inner circumferential surface (36) of the pipe end (18), wherein the angle (β) is smaller than the angle (α) and in particular is at most 2 / 3 of the angle (β). [14] HVLP spray device according to at least one of the preceding claims, characterized by that the seal (10) rests against the needle guide (13) in the axial direction and in the radial direction relative to a longitudinal axis (L8) of the valve needle (8) and is positively connected to it.

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