Connecting tube for a hand-guided, portable in use work device

Abstract

The utility model relates to a connecting pipe for a hand-guided, in-use portable work appliance for conducting an air flow from a blower of the hand-guided, in-use portable work appliance to a structural element of the work appliance. The connecting pipe is curved in an arc shape in a curved plane and has an inlet opening and an outlet opening, which are oriented relative to each other in such a way that the air flow in the connecting pipe deflects at least 70 DEG, in particular at least 80 DEG, along the longitudinal centre line in the curved plane. The connecting tubes have flow cross-sections oriented perpendicular to the longitudinal centerline, each having an internal height measured perpendicular to the bending plane. The connecting tube has an intermediate flow cross-section oriented perpendicular to the longitudinal centerline along the longitudinal centerline at an intermediate between the inlet opening and the outlet opening. Each flow cross-section has an internal width in a direction perpendicular to its internal height. An inner height of the intermediate flow cross-section is greater than an inner width of the intermediate flow cross-section.

Description

Technical Field

[0001] The invention relates to a connecting pipe for guiding an air flow from a blower of a hand-guided portable work tool to a structural element of the hand-guided portable work tool, in particular a collecting bag. Background Art

[0002] Usually, such a hand-guided portable work tool, in particular a collection bag of a suction tool, is connected to a blower of the hand-guided portable work tool via such a connecting tube (also referred to as an elbow). The arc-shaped curvature of the connecting tube in the bending plane enables an ergonomic arrangement of the collection bag and ergonomic carrying of the hand-guided work tool.

[0003] In the case of a larger blower power and a larger desired throughput through the connecting pipe, the minimum flow cross section of the connecting pipe must be selected to be large. Typically, the connecting pipe has an inlet opening and an outlet opening for the air flow, wherein the outlet opening and the inlet opening are oriented relative to each other so that the air flow turns at least 70°, especially at least 80° in the bending plane in the connecting pipe. The connecting pipe has a longitudinal centerline. Along the longitudinal centerline, the connecting pipe has a flow cross section oriented perpendicular to the longitudinal centerline. Each flow cross section has an internal height measured perpendicular to the bending plane. In order to achieve a larger flow rate for the air flowing through the connecting pipe, the minimum flow cross section in these flow cross sections must be selected to be large. Starting from the specific minimum size for the minimum flow cross section, the blower is still accessible to the user despite the bending of the connecting pipe from the outlet opening of the connecting pipe. Summary of the invention

[0004] The invention is based on the object of improving a connecting pipe of this type for conducting an air flow from a blower of a hand-guided portable work tool to a structural element of the hand-guided portable work tool, in particular a collecting bag, in such a way that a safe and flow-friendly use of the connecting pipe is possible even with high flow rates for the air flow conducted through the connecting pipe.

[0005] The object is achieved by a connecting pipe for guiding an air flow from a blower of a hand-guided portable work tool to a structural element of the hand-guided portable work tool, wherein the connecting pipe is curved in an arcuate manner in a bending plane, wherein the connecting pipe has an inlet opening for the air flow, wherein the connecting pipe has an outlet opening for the air flow, wherein the outlet opening and the inlet opening are oriented relative to one another in such a way that the air flow is deflected in the connecting pipe in the bending plane by at least 70°, in particular at least 80°, wherein the connecting pipe has a flow cross section along a longitudinal center line oriented perpendicularly to the longitudinal center line, wherein each flow cross section has an inner height measured perpendicularly to the bending plane, wherein the connecting pipe has an inner height along the longitudinal center line between the inlet opening and the outlet opening. A middle portion has an intermediate flow cross section oriented perpendicular to the longitudinal center line, wherein each flow cross section oriented perpendicular to the longitudinal center line has an internal width in a direction perpendicular to its internal height, wherein the internal height of the intermediate flow cross section is greater than the internal width of the intermediate flow cross section, wherein the connecting pipe has a tangential plane, the tangential plane extends perpendicular to the bending plane, and the tangential plane is tangential to the inlet opening in a first contact point and tangential to the outlet opening in a second contact point, wherein the first contact point and the second contact point have a point spacing, wherein each flow cross section of the connecting pipe has a plane spacing relative to the tangential plane measured perpendicular to the tangential plane, and wherein the largest plane spacing of all plane spacings of the flow cross section relative to the tangential plane is at least 25% of the point spacing.

[0006] The connecting pipe has an intermediate flow cross section oriented perpendicularly to the longitudinal center line in the middle between the inlet opening and the outlet opening along the longitudinal center line. Each flow cross section oriented perpendicularly to the longitudinal center line has an internal width in a direction perpendicular to its internal height. According to the present invention, the internal height of the intermediate flow cross section is greater than the internal width of the intermediate flow cross section. As a result, the intermediate flow cross section can have a large area and at the same time prevent reaching through the connecting pipe. The internal width of the intermediate flow cross section can be selected to be so small that the user cannot penetrate the outlet opening of the connecting pipe with his arm or with his hand through the connecting pipe to the outlet opening or grab the outlet opening. Even if the structural element (which can be configured as a collecting bag) is disassembled, the user is protected from intervening in the blower.

[0007] Despite the small internal width of the intermediate flow cross section, the area of ​​the intermediate flow cross section can be large due to the large internal height. This enables a large air flow. The connecting pipe according to the invention is simultaneously safe, designed for large blower powers and designed to be flow-friendly. The flow path of the air flow through the connecting pipe can be designed without additional structural elements for anti-interference inside the connecting pipe. As a result, an undisturbed, turbulence-free guidance of the air flow in the connecting pipe can be achieved.

[0008] Since the largest of all plane spacings of the flow cross section relative to the tangential plane is at least 25% of the point spacing, the connection tube is more strongly curved than a circular arc. In the case of a 90° circular arc, the ratio of the corresponding plane spacing to the corresponding point spacing is approximately 20%. Since this ratio is at least 25% in the case of the connection tube, effective tamper protection is achieved. The curvature prevents the user from being able to reach from the outlet opening of the connection tube to the inlet opening of the connection tube with his arm or with his hand.

[0009] Advantageously, the inner height of the intermediate flow cross section is at least 120%, in particular at least 140%, in particular at least 160% of the inner width of the intermediate flow cross section.

[0010] The central flow cross section of the connecting pipe is expediently egg-shaped. In particular, the central flow cross section of the connecting pipe is oval-shaped. As a result, the connecting pipe can be manufactured in a simple manner. Due to the egg-shaped shape of the central flow cross section, in particular due to the oval shape of the central flow cross section, the connecting pipe can be designed to be particularly stable. Due to the egg-shaped shape of the central flow cross section, in particular due to the oval shape of the central flow cross section, good flow conditions can be created inside the connecting pipe. In particular, flow separation can be avoided thereby.

[0011] In an advantageous improvement of the present invention, it is provided that the area of ​​the flow cross section of the connecting pipe increases along the longitudinal center line in the direction from the inlet opening to the outlet opening. In particular, it is provided that the area of ​​the flow cross section of the connecting pipe increases continuously along the longitudinal center line in the direction from the inlet opening to the outlet opening. Due to the increase in the area of ​​the flow cross section, the flow velocity of the air flowing through the connecting pipe decreases in the direction toward the outlet opening of the connecting pipe. The particles transported by the air flow through the connecting pipe from the inlet opening toward the outlet opening then reach the structural element connected to the connecting pipe, in particular the collecting bag connected to the connecting pipe, at a lower speed. As a result, the particles can be collected in the collecting bag without being unnecessarily rolled up by the air flow entering there. Due to the lower flow velocity of the air flow, the service life of the collecting bag can be increased.

[0012] Expediently, the inner width of the intermediate flow cross section is 90% to 110%, in particular at most 105%, in particular at most 100%, of the inner width of the flow cross section at the inlet opening.

[0013] In particular, the inner width of the intermediate flow cross section is 60% to 80%, in particular at most 70%, in particular at most 65%, of the inner width of the flow cross section of the outlet opening.

[0014] Suitably, the inner height of the intermediate flow cross section is at least 110%, in particular at least 130%, in particular at least 150% of the inner height of the flow cross section of the inlet opening. Thus, the area of ​​the intermediate flow cross section can be increased even if the inner width of the intermediate flow cross section is reduced compared to the inner width of the flow cross section at the outlet opening.

[0015] Expediently, the inner height of the intermediate flow cross section is 90% to 110%, in particular 95% to 105%, in particular less than 100%, of the inner height of the flow cross section of the outlet opening.

[0016] Advantageously, the flow cross section of the inlet opening of the connecting pipe is circular. This allows simple production of the connecting pipe. The circular shape of the flow cross section of the inlet opening allows simple connection of the connecting pipe to the blower of a hand-guided work tool that can be carried during use.

[0017] The connecting pipe has a tangent plane. The tangent plane extends perpendicularly to the bending plane. In particular, the tangent plane is tangent to the inlet opening in a first contact point and simultaneously tangent to the outlet opening in a second contact point. In particular, the tangent plane does not intersect any flow cross section of the connecting pipe. Advantageously, the tangent plane only abuts against the total set of flow cross sections and does not intersect the total set of flow cross sections.

[0018] The first contact point of the inlet opening has a point spacing with the second contact point of the outlet opening. Each flow cross section of the connecting pipe has a plane spacing relative to the tangential plane measured perpendicular to the tangential plane. The plane spacing of the individual flow cross sections can also be zero. This applies in particular to flow cross sections that are tangential to the tangential plane.

[0019] In an advantageous development of the invention, the largest plane spacing of all plane spacings of the flow cross section is at least 30%, preferably at least 35%, of the point spacing. As a result, the connecting pipe is more strongly curved than a circular arc. In the case of a 90° circular arc, the ratio of the corresponding plane spacing to the corresponding point spacing is approximately 20%. Since this ratio is at least 30%, in particular at least 35%, in the case of the connecting pipe, an even more effective protection against tampering is obtained.

[0020] The connecting tube has a radius of curvature in the bending plane at the middle flow cross section on the more strongly curved side of the connecting tube. Advantageously, the radius of curvature is less than 50% of the point spacing, expediently less than 40% of the point spacing, in particular less than 30% of the point spacing. Due to this curvature, a reliable protection against tampering can be achieved. The curvature prevents a user from being able to reach into the inlet opening of the connecting tube with his arm or with his hand from the outlet opening of the connecting tube.

[0021] Advantageously, the connecting pipe has no grille bars for anti-interference. This can prevent the formation of turbulence in the air flow. This can prevent negative influences on the air flow. By omitting the grille bars for anti-interference, the sound emission of the connecting pipe can be reduced.

[0022] The discharge opening has a discharge edge. In an advantageous development of the invention, it is provided that the discharge edge has at least one projection protruding in the direction of the longitudinal center line. In particular, the projection protrudes in the direction of the longitudinal center line relative to the base body of the connecting tube. Due to the projection, the sound emission generated by the air flow discharged from the discharge opening of the connecting tube is reduced. Since a part of the air flow accelerated by the blower can be discharged from the connecting tube at a location of the discharge edge, which is arranged closer to the inlet opening along the longitudinal center line than the end of the projection farthest from the inlet opening along the longitudinal center line, the air mass compressed by the blower does not relax all at once. A part of the compressed air mass is discharged from the connecting tube only at the end of the projection. The discharge of the air mass or air flow from the connecting tube is distributed over the projection height measured along the longitudinal center line of the projection. A reduction in sound emission is thereby achieved.

[0023] The projection has a projection height. The projection height is measured in the direction of the longitudinal center line. The projection height is measured starting from the base body of the connecting pipe. Advantageously, the projection height is at least 20%, in particular at least 30%, in particular at least 40% of the inner width of the flow cross section of the outlet opening of the connecting pipe. As a result, the pressure of the air flow can be reduced over a sufficiently long section when it is discharged from the outlet opening of the connecting pipe.

[0024] Suitably, the discharge edge has a plurality of projections. In particular, due to the plurality of projections, the discharge edge is wavy. This pattern is called a Chevron pattern in the discharge edges of propulsion nozzles of aircraft. This sawtooth pattern leads to a better mixing of air flow portions of different speeds. The pattern does not necessarily have to be strictly sawtooth-shaped. It can also be provided that the tips of the sawtooth are rounded. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] An embodiment of the present invention is explained below with the aid of the accompanying drawings. In the accompanying drawings:

[0026] Figure 1A perspective view of a hand-guided working tool designed as a suction device and which can be carried during use, with a connecting pipe for guiding an air flow from a blower of the working tool to a structural element of the hand-guided working tool designed as a collecting bag;

[0027] Figures 2 to 5 Show Figure 1 A perspective view of the connecting pipe in FIG.

[0028] Figure 6 Shown along the curved plane of the connecting pipe through Figures 2 to 5 A cross-sectional view of a cross section of a connecting pipe in FIG.

[0029] Figure 7 Shown along Figure 6 A sectional view of the section along the cutting plane VII-VII drawn in FIG.

[0030] Figure 8 Shown along Figure 6 A sectional view of the section along the cutting plane VIII-VIII drawn in FIG.

[0031] Fig. 9 Shown along Figure 6 A sectional view of the section along the cutting plane IX-IX drawn in FIG.

[0032] Fig.10 The bending direction of the connecting pipe is shown perpendicular to the bending plane. Figures 2 to 9 Top view of the connecting pipe in . DETAILED DESCRIPTION

[0033] Figure 1 A work tool 1 is shown. The work tool 1 is a hand-guided work tool that is portable in the case of intended use. In the present embodiment, the work tool 1 is a suction tool. However, it can also be provided that the work tool is a suction / blowing tool. The work tool can also be another hand-guided work tool in which a blower delivers an air flow to a structural element (such as a collecting bag).

[0034] In the present embodiment, the working tool 1 comprises a blower 2. The working tool 1 comprises a structural element 3. In the present embodiment, the structural element 3 is configured as a collection bag. The working tool 1 comprises a connecting pipe 4. The connecting pipe 4 connects the blower 2 with the structural element 3. The connecting pipe 4 is used to guide the air flow from the blower 2 to the structural element 3. The blower 2 conveys air to the structural element 3 configured as a collection bag through the connecting pipe 4.

[0035] The working tool 1 has a suction pipe 5. The blower 2 generates an air flow, which is sucked through the suction pipe 5. When the working tool 1 is in use, the air flow is used to suck in objects to be sucked in, such as leaves or cut materials, and they are transported to a collection bag through the connecting pipe 4 via the blower 2. The working tool 1 includes a bow handle 6. The working tool 1 includes an operating handle 7. The operating handle 7 is constructed separately from the bow handle 6. When the working tool 1 is in use, the bow handle 6 is used to carry and guide the working tool 1. When the working tool 1 is in use, the operating handle 7 is used to guide and operate the working tool 1. An operating element 8 is provided at the operating handle 7. The power of a motor not shown can be controlled by the operating element 8. In the present embodiment, the motor is an electric motor. But it can also be an internal combustion engine. The motor drives the blower 2.

[0036] In the present embodiment, the operating handle 7 delimits a handle opening 9. The operator can reach through the handle opening 9 and thereby grasp the operating handle 7. The handle opening 9 extends in a handle plane G. The holding region 41 of the bow handle 6 extends transversely to the handle plane G of the handle opening 9, in the present embodiment perpendicularly.

[0037] The connecting pipe 4 is also arranged on one side of the handle plane G of the handle opening 9. The connecting pipe 4 is arranged at the end of the suction pipe 5 facing away from the inlet opening 10 of the suction pipe 5. The connecting pipe 4 is arranged in the area of ​​the blower 2. The connecting pipe 4 is arranged between the operating handle 7 and the suction pipe 5. The connecting pipe 4 is fixed to the housing of the working tool 1. The housing has a housing opening that is not shown. The housing opening completely passes through the wall 45 of the housing that limits the housing to the outside of the housing. The housing opening is used to guide the air flow generated by the blower from the inside of the housing to the outside of the housing or to the structural element 3 configured as a collection bag. The connecting pipe 4 is arranged on the housing opening. The connecting pipe 4 covers the housing opening. The connecting pipe 4 is connected to the housing in an airtight manner.

[0038] The connecting pipe 4 is tubular. The outer wall 43 of the connecting pipe 4 surrounds the inner space of the connecting pipe 4. The outer wall 43 of the connecting pipe 4 has an inlet opening 10 and an outlet opening 30 as openings leading to the inner space.

[0039] like Figure 2 As also shown in FIG. 1 , the connecting pipe 4 is curved. The connecting pipe 4 is in the bending plane K (the bending plane is also Figure 6 The bending plane K is curved in an arc shape. Figure 1 The bending plane K extends transversely to the handle plane G. In this embodiment, the bending plane K extends perpendicular to the handle plane G. Figure 1As can be seen in the figure, due to the arcuate curvature of the connecting tube 4, the structural element 3 configured as a collection bag can be arranged next to the blower 2. The collection bag can be arranged next to the suction tube 5, spaced apart from the suction tube 5. Due to the curvature of the connecting tube 4, the collection bag can be arranged in a plane extending parallel to the handle plane G. Due to the arcuate curvature of the connecting tube 4, the working tool 1 is ergonomically designed. In use, the operator can hold the working tool 1 at the bow handle 6, operate the working tool with the operating handle 7, and at the same time put the structural element 3 configured as a collection bag aside and use Figure 1 4. The air flow is carried by the carrying ring belt 42 shown in the drawing. Due to the arcuate curvature of the connecting pipe 4, the objects to be sucked in can be deflected downward from the blower 2 during the use of the working tool 1. In this way, the sucked objects can be collected in the structural element 3 configured as a collection bag in a simple manner by utilizing gravity. Due to the arcuate curvature of the connecting pipe 4, the air flow is decelerated on its way to the structural element 3 configured as a collection bag. This reduces turbulence in the collection bag and increases the service life of the collection bag.

[0040] The connecting pipe 4 is also called an elbow. Figure 2 As shown in the figure, the connecting pipe 4 has an inlet opening 10. The inlet opening 10 is used for the air flow to enter the connecting pipe 4. The connecting pipe 4 has an outlet opening 30. The air flow can be discharged from the connecting pipe 4 through the outlet opening 30. In the present embodiment, the connecting pipe is arranged in the working tool 1 so that the inlet opening 10 is in the vicinity of the blower 2. The end of the connecting pipe 4 with the outlet opening 30 points away from the blower 2. The outlet opening 30 of the connecting pipe 4 is connected to the structural element 3 configured as a collection bag. The air flow enters the structural element 3 configured as a collection bag through the outlet opening 30.

[0041] The outlet opening 30 and the inlet opening 10 are oriented relative to one another in such a way that the air flow in the connecting pipe 4 is directed in the bending plane K in a direction of Fig.10 , in the embodiment shown in the figure, the steering angle α of at least 70° is used for steering, in the embodiment shown in the figure, the steering angle α of at least 80° is used for steering. In the embodiment shown in the figure, the steering angle α is about 90°. In particular, the steering angle α is exactly 90°. In the embodiment shown in the figure, the steering angle α is at most 120°, in particular at most 110°. Between the inlet opening 10 and the outlet opening 30, the air flow changes its direction along a single arc. Starting from the inlet opening 10, the air flow always changes only in the direction of the outlet opening 10 due to the guidance through the connecting pipe 4.

[0042] like Fig.10As shown in , the connecting pipe 4 has a longitudinal centerline 50. The air flow is transported from the inlet opening 10 through the connecting pipe 4 to the outlet opening 30 along the longitudinal centerline 50. The longitudinal centerline 50 is curved in an arc. The longitudinal centerline 50 extends through the center of gravity of the surface of the flow cross section of the connecting pipe 4. The bending plane K contains the longitudinal centerline 50. The longitudinal centerline 50 is also called the longitudinal center axis, the center of gravity line or the center of gravity axis. The longitudinal centerline 50 has a length of up to 850 mm measured along the curved longitudinal centerline 50 from the inlet opening 10 to the outlet opening 30. The length of the longitudinal centerline 50 is suitably determined by the path integral along the longitudinal centerline 50 from the inlet opening 10 to the outlet opening 30.

[0043] The connecting pipe 4 has a flow cross section along the longitudinal center line 50 which is oriented perpendicular to the longitudinal center line 50. Figures 7 to 9 Flow cross sections 13, 23 and 33 are shown by way of example in FIG. The outer wall 43 of the connecting pipe delimits the flow cross sections 13, 23, 33. Each flow cross section 13, 23, 33 has an inner height h1, h2, h3 measured perpendicularly to the bending plane K. Figure 7 The flow cross section 13 of the inlet opening 10 shown in FIG. 1 has an inner height h1 . Figure 8 The flow cross section 23 shown in FIG. 2 has an inner height h2 . Fig. 9 The flow cross section 33 of the outlet opening 30 shown in FIG. 1 has an inner height h3 . Figure 8 The flow cross section 23 shown in the figure is also referred to as the intermediate flow cross section 20. The intermediate flow cross section 20 is oriented perpendicularly to the longitudinal center line 50. The intermediate flow cross section 20 is arranged along the longitudinal center line 50 in the middle between the inlet opening 10 and the outlet opening 30. The intermediate flow cross section 20 has an inner height h2. The inner heights h1, h2, h3 are each the maximum extent of the associated flow cross section 13, 23, 33 measured in a direction perpendicular to the bending plane K.

[0044] The longitudinal center line 50 has an integral length in the region between the inlet opening 10 and the outlet opening 30. The intermediate flow cross section 20 divides the section associated with this length into two sections of equal length.

[0045] Each flow cross section oriented perpendicularly to the longitudinal center line 50 has an inner width. The inner width is measured parallel to the bending plane K. In the present exemplary embodiment, the inner width is measured in the bending plane K. The inner width is measured perpendicularly to the inner height. In the direction parallel to the bending plane K, the inner width is the maximum extent of the associated flow cross section. Figure 7 , Figure 8 and Fig. 9 In the example, the inner widths b1, b2 and b3 are drawn. The inner width b1 is associated with the flow cross section 13 of the inlet opening 10 ( Figure 7 ).like Figure 8 As shown in FIG, the inner width b2 is associated with the flow cross section 23, in the present embodiment, with the intermediate flow cross section 20. Fig. 9 As shown in , the inner width b3 is the width of the flow cross section 33 of the outlet opening 30. The inner height h1 extends perpendicularly to the inner width b1. The inner height h2 extends perpendicularly to the inner width b2. The inner height h3 extends perpendicularly to the inner width b3.

[0046] The inner height h2 of the intermediate flow cross section 20 is greater than the inner width b2 of the intermediate flow cross section 20 ( Figure 8 ). The inner height h2 of the intermediate flow cross section 20 is at least 120%, in particular at least 140%, in the present exemplary embodiment at least 160%, of the inner width b2 of the intermediate flow cross section 20 .

[0047] In particular, the inner height h2 of the central flow cross section 20 is at most 200%, in particular at most 190%, in the present exemplary embodiment at most 180%, of the inner width b2 of the central flow cross section.

[0048] The middle flow cross section 20 of the connecting pipe 4 has an egg-like shape. In the present embodiment, the middle flow cross section 20 of the connecting pipe 4 has an elliptical shape. In particular, the shape of the middle flow cross section 20 deviates from a circular shape.

[0049] The internal height of each individual flow cross section of a set of flow cross sections from the connecting pipe 4 along the longitudinal center line 50 starting from the outlet opening 30 in the direction of the inlet opening 10 over at least 60%, in particular at least 70%, and in the present embodiment at least 80% of the section of the longitudinal center line 50 between the inlet opening 10 and the outlet opening 30 is advantageously greater than the internal width corresponding to the individual flow cross section.

[0050] The individual flow cross sections of the set of flow cross sections from the connecting pipe 4 along the longitudinal center line 50 starting from the outlet opening 30 in the direction of the inlet opening 10 over at least 60%, in particular at least 70%, and in the present embodiment at least 80% of the section of the longitudinal center line 50 between the inlet opening 10 and the outlet opening 30 have an egg-shaped shape, in the present embodiment an elliptical shape.

[0051] As from Figures 2 to 6 The area of ​​the flow cross section of the connecting pipe 4 increases along the longitudinal center line 50 in the direction from the inlet opening 10 to the outlet opening 30. This is shown in FIG. Figures 7 to 94 shows the flow cross section 13 at the inlet opening 510, the flow cross section 23 at the middle of the connecting pipe 4 along the longitudinal center line 50, and the flow cross section 33 at the outlet opening 30. In this embodiment, the areas of the flow cross sections 13, 23, 33 of the connecting pipe 4 increase continuously along the longitudinal center line 50 in the direction from the inlet opening 10 to the outlet opening 30.

[0052] The inner width b2 of the intermediate flow cross section 20 is 90% to 110%, in particular at most 100%, of the inner width b1 of the flow cross section 13 of the inlet opening 10 .

[0053] The inner width b2 of the intermediate flow cross section 20 is 60% to 80% of the inner width b3 of the flow cross section 33 of the outlet opening 30. Figure 6 As can also be seen in FIG. 2 , the inner width b2 of the central flow cross section 20 is the smallest inner width of the connecting pipe 4 , in particular the smallest inner width of all flow cross sections of the connecting pipe 4 .

[0054] Figure 8 The inner height h2 of the intermediate flow cross section 20 shown in FIG. Figure 7 At least 110%, in particular at least 130%, in the present exemplary embodiment at least 150%, of the inner height h1 of the flow cross section 13 of the inlet opening 10 shown in FIG.

[0055] The inner height h2 of the intermediate flow cross section 20 is 90% to 110%, in particular 95% to 105%, in the present embodiment less than 100% of the inner height h3 of the flow cross section 33 of the outlet opening 30. In the present embodiment, the inner height of the connecting pipe 4, in particular the inner heights of all flow cross sections of the connecting pipe 4, increases, in particular continuously, starting from the inlet opening 10 along the longitudinal center line 50 up to the outlet opening 30.

[0056] like Figure 7 As shown in FIG. 1 , the flow cross section 13 of the inlet opening 10 of the connecting pipe 4 is circular.

[0057] In the present embodiment, the inner height h1 of the flow cross section 13 of the inlet opening 10 is 25 mm to 135 mm, in particular 45 mm to 115 mm, in particular 55 mm to 105 mm.

[0058] In the present embodiment, the inner width b1 of the flow cross section 13 of the inlet opening 10 is 25 mm to 135 mm, in particular 45 mm to 115 mm, in particular 55 mm to 105 mm.

[0059] In the present embodiment, the inner height h2 of the intermediate flow cross section 20 is 90 mm to 190 mm, in particular 110 mm to 170 mm, in particular 120 mm to 160 mm.

[0060] In the present embodiment, the inner width b2 of the intermediate flow cross section 20 is 25 mm to 135 mm, in particular 45 mm to 115 mm, in particular 55 mm to 105 mm.

[0061] In the present embodiment, the inner height h3 of the flow cross section 33 of the outlet opening 30 is 100 mm to 200 mm, in particular 120 mm to 180 mm, in particular 130 mm to 170 mm.

[0062] In the present embodiment, the inner width b3 of the flow cross section 33 of the outlet opening 30 is 70 mm to 170 mm, in particular 90 mm to 150 mm, in particular 100 mm to 140 mm.

[0063] like Fig.10 As shown in , the connecting pipe 4 has a tangential plane T. The tangential plane T extends perpendicular to the bending plane K. The tangential plane T is tangential to the inlet opening 10 at the first contact point P1 and is simultaneously tangential to the outlet opening 30 at the second contact point P2. The tangential plane T intersects neither the outlet opening 30 nor the inlet opening 10. The tangential plane T is only tangential to the flow cross section of the connecting pipe 4. None of the flow cross sections of the connecting pipe 4 intersects with the tangential plane T. In particular, the tangential plane T abuts against the flow cross section 13 of the inlet opening 10 and simultaneously abuts against the flow cross section 33 of the outlet opening 30. Neither the flow cross section 13 of the inlet opening 10 nor the flow cross section 33 of the outlet opening 30 intersects with the tangential plane T. The tangential plane T is on the side of the connecting pipe 4 that is more strongly bent.

[0064] The first contact point P1 is at the edge of the inlet opening 10. The first contact point P1 is at the edge of the flow cross section 13 of the inlet opening 10. The second contact point P2 is at the edge of the outlet opening 30. The second contact point P2 is at the edge of the flow cross section 33 of the outlet opening 30.

[0065] The first contact point P1 has a point spacing s relative to the second contact point P2 . In the present exemplary embodiment, both the contact point P1 and the contact point P2 are located in the bending plane K. The point spacing s is measured in the bending plane K.

[0066] Each flow cross section of the connecting pipe 4 has a plane spacing relative to the tangential plane T measured perpendicularly to the tangential plane T. For example, the flow cross sections 13, 23 and 33 of the connecting pipe 4 are Fig.10, the flow cross sections each have a plane spacing relative to the tangential plane T. For the flow cross section 13 of the inlet opening 10, the plane spacing is zero. Likewise, the plane spacing for the flow cross section 33 of the outlet opening 30 is also zero.

[0067] The set of all plane spacings includes the largest plane spacing d. In the present embodiment, the largest plane spacing d exists at the location of the middle flow cross section 20. The plane spacing of the middle flow cross section 20 is the largest plane spacing d among all plane spacings. Among all flow cross sections of the connecting pipe 4, the middle flow cross section 20 has the largest plane spacing, i.e., the largest plane spacing d. The largest plane spacing d is at least 25%, in particular at least 30%, in the present embodiment at least 35% of the point spacing s. This prevents the user from reaching the inlet opening 10 of the connecting pipe from the outlet opening 30 through the connecting pipe 4 with his hand or arm. Due to the large maximum plane spacing d, the (direct) path from the outlet opening 30 through the connecting pipe 4 to the inlet opening 10 is so narrowed or bent that the user cannot reach through with his hand or his arm. The hand or arm cannot be bent to such a strong degree.

[0068] In particular, the maximum plane spacing d is at most 70%, in particular at most 60%, in the present exemplary embodiment at most 50%, of the point spacing s.

[0069] like Fig.10 As shown in FIG, the connecting pipe 4 has a radius of curvature r1 on its more strongly curved side in the bending plane K at the center flow cross section 20. The more strongly curved side of the connecting pipe 4 is also referred to as the inner curved side. The radius of curvature r1 is less than 50% of the point spacing s, in particular less than 40% of the point spacing, in the present embodiment less than 30% of the point spacing. The radius of curvature r1 at the center flow cross section 20 is a measure of the curvature of the more strongly curved side of the connecting pipe 4 in the bending plane K. The smaller the radius of curvature, the greater the curvature.

[0070] Due to the small ratio of the radius of curvature r1 to the point spacing s, the curvature at the intermediate flow cross section 20 is large. The strong curvature of the connecting tube 4 provides an anti-tampering feature. The strong curvature prevents the user from being able to reach the inlet opening 10 or reach the inlet opening with his hand or his arm from the outlet opening 30 through the connecting tube 4.

[0071] This tamper protection is provided even if the connecting pipe 4 has no lattice bars for tamper protection.

[0072] In the present exemplary embodiment, the radius of curvature r1 is greater than 10% of the point spacing s, in particular greater than 20% of the point spacing s.

[0073] like Fig.10As shown in FIG. 4 , the edge of the inlet opening 10 in the bending plane K has a first secant point S1 which is located outside with respect to the bend of the connecting pipe 4 . The first secant point S1 is located in the bending plane K. The first secant point S1 is located at the edge of the flow cross section 13 of the inlet opening 10 .

[0074] The edge of the outlet opening 30 has a second secant point S2 in the bending plane K on the side lying outside with respect to the bend of the connecting piece 4 . The second secant point S2 is in the bending plane K. The second secant point S2 is at the edge of the flow cross section 33 of the outlet opening 30 .

[0075] The straight line g extends through the first secant point S1 and the second secant point S2 . The straight line g extends along a direct connecting line between the outlet opening 30 and the inlet opening 10 .

[0076] The connecting pipe 4 has an outer wall 43. The straight line g intersects the outer wall 43. In particular, the straight line g intersects the outer wall 43 in the following area of ​​the outer wall 43, which area is on the side of the connecting pipe 4 that is more strongly curved. The intermediate flow cross section 20 is arranged to be spaced apart from the straight line g by a straight line spacing a measured perpendicular to the straight line g. The straight line spacing a is at least 1%, in particular at least 3%, preferably at least 5%, and in the present embodiment at least 7% of the point spacing s. The second secant point S2 is arranged to be spaced apart from the first secant point S1 by a secant point spacing w. In the present embodiment, the secant point spacing w is measured in the bending plane K. The straight line spacing a is at least 1%, in particular at least 3%, and in the present embodiment at least 5%. In the present embodiment, the straight line spacing a is at most 50%, in particular at most 30%, and in the present embodiment at most 15% of the secant point spacing w.

[0077] Since the straight line g intersects the outer wall 43 of the connecting tube 4, it is not possible to grip through the connecting tube 4 on a straight direct path from the outlet opening 30 to the inlet opening 10. In a corresponding test, the operator hit the inside of the outer wall 43. The inside of the outer wall 43 delimits the entire flow cross section of the connecting tube 4.

[0078] like Figure 6 As shown in FIG. 4 , the discharge opening 30 has a discharge edge 31. The discharge edge 31 has at least one projection 32 in the direction of the longitudinal center line 50. The projection 32 protrudes relative to the base body 44 of the connecting tube 4. Figure 6 In FIG. 5 , an imaginary separation between the base body 44 and the projection 32 is marked by a dashed line. The corresponding separation plane extends perpendicularly to the longitudinal center line 50 .

[0079] The projection 32 has a projection height v. The projection height v is at least 20%, in particular at least 30%, in the present embodiment at least 40% of the inner width b3 of the flow cross section 33 of the outlet opening 30 of the connecting tube 4. The projection height v is measured at the outlet opening 30 in the direction of the longitudinal center line 50. The projection height v is measured starting from the dividing plane between the base body 44 and the projection 32 in the direction of the projection 32. The projection height v is measured perpendicularly to the dividing plane between the base body 44 and the projection 32.

[0080] The discharge edge 31 has a plurality of projections 32. Due to the plurality of projections 32, the discharge edge 31 is wavy. Such a wavy pattern is also referred to as a V-pattern. Such a pattern is known from jet propulsion devices for aircraft.

[0081] The discharge edge 31 is closed around the longitudinal center line 50. Figure 2 and Figure 3 As shown in FIG. 1 , in the present exemplary embodiment, a total of six projections 32 are provided. Due to the projections 32, the circumferential discharge edge 31 is designed in a wave-like manner.

Claims

1. A connecting pipe for guiding an air flow from a blower (2) of a hand-guided portable work tool (1) to a structural element (3) of the hand-guided portable work tool (1), wherein: The connecting tube (4) is curved in an arc in a bending plane (K), wherein the connecting tube (4) has an inlet opening (10) for the air flow, wherein the connecting tube (4) has an outlet opening (30) for the air flow, wherein the outlet opening (30) and the inlet opening (10) are oriented relative to one another in such a way that the air flow in the connecting tube (4) is deflected by at least 70° in the bending plane (K), wherein the connecting tube (4) has a flow cross section (13, 23, 33) along a longitudinal center line (50) oriented perpendicularly to the longitudinal center line (50), wherein each flow cross section (13, 23, 33) has a The connecting pipe (4) has an inner height (h1, h2, h3) measured from the bending plane (K), wherein the connecting pipe (4) has an intermediate flow cross section (20) oriented perpendicularly to the longitudinal center line (50) at the middle between the inlet opening (10) and the outlet opening (30) along the longitudinal center line (50), wherein each flow cross section (13, 23, 33) oriented perpendicularly to the longitudinal center line (50) has an inner width (b1, b2, b3) in a direction perpendicular to its inner height (h1, h2, h3), wherein the inner height (h2) of the intermediate flow cross section (20) is greater than the inner width (b2) of the intermediate flow cross section (20), Characterized in that the connecting pipe (4) has a tangential plane (T), which extends perpendicularly to the bending plane (K), and the tangential plane is tangential to the inlet opening (10) at a first contact point (P1) and tangential to the outlet opening (30) at a second contact point (P2), the first contact point (P1) and the second contact point (P2) having a point spacing (s), each flow cross section (13, 23, 33) of the connecting pipe (4) having a plane spacing relative to the tangential plane (T) measured perpendicularly to the tangential plane (T), and the largest plane spacing (d) of all plane spacings of the flow cross section (13, 23, 33) relative to the tangential plane (T) is at least 25% of the point spacing (s).

2. The connecting pipe according to claim 1, characterized in that: The inner height (h2) of the intermediate flow cross section (20) is at least 120% of the inner width (b2) of the intermediate flow cross section (20).

3. The connecting pipe according to claim 1, characterized in that: The central flow cross section (20) of the connecting pipe (4) has an egg-shaped shape.

4. The connecting pipe according to claim 1, characterized in that: The central flow cross section (20) of the connecting pipe (4) has an elliptical shape.

5. The connecting pipe according to claim 1, characterized in that: The area of ​​the flow cross section (13, 23, 33) of the connecting pipe (4) increases along the longitudinal center line (50) in the direction from the inlet opening (10) to the outlet opening (30).

6. The connecting pipe according to claim 1, characterized in that: The area of ​​the flow cross section (13, 23, 33) of the connecting pipe (4) increases continuously along the longitudinal center line (50) in the direction from the inlet opening (10) to the outlet opening (30).

7. The connecting pipe according to claim 1, characterized in that: The inner width (b2) of the intermediate flow cross section (20) is 90% to 110% of the inner width (b1) of the flow cross section (13) at the inlet opening (10).

8. The connecting pipe according to claim 1, characterized in that: The inner width (b2) of the intermediate flow cross section (20) is 60% to 80% of the inner width (b3) of the flow cross section (33) of the outlet opening (30).

9. The connecting pipe according to claim 1, characterized in that: The inner height (h2) of the intermediate flow cross section (20) is at least 110% of the inner height (h1) of the flow cross section (13) of the inlet opening (10).

10. The connecting pipe according to claim 1, characterized in that: The inner height (h2) of the intermediate flow cross section (20) is at least 130% of the inner height (h1) of the flow cross section (13) of the inlet opening (10).

11. The connecting pipe according to claim 1, characterized in that: The inner height (h2) of the intermediate flow cross section (20) is at least 150% of the inner height (h1) of the flow cross section (13) of the inlet opening (10).

12. The connecting pipe according to claim 1, characterized in that: The inner height (h2) of the intermediate flow cross section (20) is 90% to 110% of the inner height (h3) of the flow cross section (33) of the outlet opening (30).

13. The connecting pipe according to claim 1, characterized in that: The inner height (h2) of the intermediate flow cross section (20) is less than 100% of the inner height (h3) of the flow cross section (33) of the outlet opening (30).

14. The connecting pipe according to claim 1, characterized in that: The flow cross section (13) of the inlet opening (10) of the connecting pipe (4) is circular.

15. The connecting pipe according to claim 1, characterized in that: The largest plane spacing (d) of all plane spacings of the flow cross sections (13, 23, 33) relative to the tangential plane (T) is at least 30% of the point spacing (s).

16. The connecting pipe according to claim 1, characterized in that: The connecting piece (4) has a radius of curvature (r1) on the more strongly curved side of the connecting piece (4) in the bending plane (K) at the central flow cross section (20), which is less than 50% of the point spacing (s).

17. The connecting pipe according to claim 1, characterized in that: The connecting pipe (4) has no grid bars for preventing intervention.

18. The connecting pipe according to claim 1, characterized in that: The discharge opening (30) has a discharge edge (31), and the discharge edge (31) has at least one projection (32) in the direction of the longitudinal center line (50).

19. The connecting pipe according to claim 18, characterized in that: The projection (32) has a projection height (v), and the projection height (v) is at least 20% of the inner width (b3) of the flow cross section (33) of the outlet opening (30) of the connecting pipe (4).

20. The connecting pipe according to claim 18, characterized in that The discharge edge (31) has a plurality of projections (32), and the discharge edge (31) is wavy due to the plurality of projections (32).

21. The connecting pipe according to claim 1, characterized in that: The structural element (3) is a collecting bag.

22. The connecting pipe according to claim 1, characterized in that: The air flow in the connecting pipe (4) is deflected by at least 80° in the bending plane (K).

23. The connecting pipe according to claim 1, characterized in that The inner height (h2) of the intermediate flow cross section (20) is at least 140% of the inner width (b2) of the intermediate flow cross section (20).

24. The connecting pipe according to claim 1, characterized in that The inner height (h2) of the intermediate flow cross section (20) is at least 160% of the inner width (b2) of the intermediate flow cross section (20).

25. The connecting pipe according to claim 1, characterized in that The inner height (h2) of the intermediate flow cross section (20) is 95% to 105% of the inner height (h3) of the flow cross section (33) of the outlet opening (30).

26. The connecting pipe according to claim 1, characterized in that The largest plane spacing (d) of all plane spacings of the flow cross sections (13, 23, 33) relative to the tangential plane (T) is at least 35% of the point spacing (s).

27. The connecting pipe according to claim 1, characterized in that The connecting piece (4) has in the bending plane (K) at the central flow cross section (20) on the more strongly curved side of the connecting piece (4) a radius of curvature (r1) which is less than 40% of the point spacing (s).

28. The connecting pipe according to claim 1, characterized in that The connecting piece (4) has a radius of curvature (r1) on the more strongly curved side of the connecting piece (4) in the bending plane (K) at the central flow cross section (20), which is less than 30% of the point spacing (s).

29. The connecting pipe according to claim 18, characterized in that The projection (32) has a projection height (v), and the projection height (v) is at least 30% of the inner width (b3) of the flow cross section (33) of the outlet opening (30) of the connecting pipe (4).

30. The connecting pipe according to claim 18, characterized in that The projection (32) has a projection height (v), and the projection height (v) is at least 40% of the inner width (b3) of the flow cross section (33) of the outlet opening (30) of the connecting pipe (4).

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