Safety valve for a pneumatically operated tool

Abstract

This invention relates to a pneumatic tool comprising a handle (26), a valve (22), a safety switch lever (18) arranged on the handle (26) for operating the valve (22), and a pressure medium connector (16), wherein the valve (22) comprises a valve body (28) movable between a base position and at least one other position, wherein in the base position the connection between the pressure medium connector (16) and the pressure cylinder (12) of the tool is interrupted, and in the other positions the connection between the pressure medium connector (16) and the pressure cylinder (12) of the tool is established. The pressure cylinder (12) is vented as the valve body (28) moves toward the base position, and the pressure acting on the pressure medium connector (16) causes the valve body (28) to move toward the base position when the safety switch lever (18) is released.

Description

Technical Field

[0001] This invention relates to a pneumatically operated tool. Background Technology

[0002] A device for pneumatic operation of tools and a pneumatic clamp are known from document EP 1163979 A1.

[0003] Pneumatic pliers are known for clamping and locking clamping rings, pins, cable connectors, spring clips, etc. They are particularly useful in the automotive industry, where they are used to lock locking rings during the assembly of hoses, bellows, etc., onto supports, universal joints, etc.

[0004] Pressure medium clamps with spring bands are known from document DE 3742782 A, which have valve-controlled pressure medium fittings and wedge-shaped feed mechanisms. Other clamps of this type are known from documents DE 89 00 250U, DE 195 19543A, DE 295 09 976U and DE 91 11 366 U.

[0005] In tools known from the prior art, pressure is applied to a pressure cylinder by operating a trigger unit. In some cases, the tool or pressure supply includes an electronic regulating unit, which may malfunction and accidentally apply pressure to the trigger unit, closing the tool. Tools according to the prior art lack mechanical safety devices that should be able to interrupt the energy input (pressurized air). If pressure is accidentally applied to the trigger unit, for example due to a software error, the pliers and their jaws close. This can lead to a dangerous situation. Therefore, different standards guarantee against such accidental closure. Since hardware with a simple structure according to common standards is not entirely reliable, the trigger unit must be designed redundantly, especially by utilizing electronically redundant regulating units. Summary of the Invention

[0006] The technical problem to be solved by the present invention is particularly to provide an alternative to the electronic redundancy structure relative to the triggering unit, and to effectively avoid damage to the tool caused by accidental pressure application.

[0007] This invention is based on a pneumatic tool, particularly an electronically regulated pneumatic tool, wherein the applied pressure is monitored electronically. The tool includes a handle, a safety switch lever arranged on the handle for operating a valve, and a pressure medium connector, wherein the valve includes a valve body movable between a base position and at least one other position, wherein in the base position the connection between the pressure medium connector and the tool's pressure cylinder is interrupted, and in the other positions the connection between the pressure medium connector and the tool's pressure cylinder is established.

[0008] The tools described may in particular involve pliers, however, the invention may also be considered for use with other tools.

[0009] As specified, the pressure cylinder releases air as the valve body moves toward the base position, and the pressure acting on the pressure medium connector causes the valve body to move toward the base position when the safety switch lever is released. When the user releases the safety switch lever, for example, by leaving the room, the valve reliably returns to the base position without manual intervention due to the pressure. Simultaneously, the pressure cylinder releases air, thus reliably removing any potentially stuck components, such as fingers or clothing.

[0010] In a particularly advantageous design of the invention, the valve body is constructed as a movable ring (or bushing, collar) on the pressure supply connector pipe, the inner surface of which, together with the outer surface of the pressure supply connector pipe, forms a pressure chamber, wherein the two axial end faces of the pressure chamber are formed by the inner surface of the ring and have different areas, or pressure application surfaces. This allows the desired functionality to be achieved in a robust and compact manner.

[0011] This allows for the simple realization of different pressure application surfaces, especially when the outer diameter of the pressure supply connector pipe on the side open towards the pressure cylinder is larger than the outer diameter of the pressure supply connector pipe on the side open towards the pressure medium connector. Here, for an axially movable shaft ring, the axial projection of the inner end face of the shaft ring corresponds to the pressure application surface.

[0012] In a preferred embodiment of the invention, the pressure supply connector tube may include a first internal bore opening toward a medium connector and a second internal bore opening toward a pressure cylinder, as well as first and second pressure passage holes, particularly radially, wherein the latter communicate with the outer surface of the pressure supply connector tube, respectively. In the base position, the first passage hole leads into the pressure chamber, and the second passage hole is freely open for venting. This allows venting from the pressure cylinder in the base position. In the other positions, both the first and second passage holes lead into the pressure chamber, thereby transmitting pressure from the pressure medium connector through the first pressure passage hole into the pressure chamber, from there through the second pressure passage hole to the second internal bore, and further to the pressure cylinder.

[0013] In another design, the tool also includes a spring that generates a reset force, which pushes the valve body to the base position when the safety switch lever is released. The spring can provide pressure during the valve body reset process, thus allowing the valve to transition to the safer closed base position even at lower pressures (or even when there is no pressure in the system). Here, the spring can be designed to reliably and consistently overcome the additional frictional forces of the valve body, thus providing additional redundancy to the safety valve.

[0014] In other words, this invention specifies that a 3 / 2-way safety valve is directly provided in the triggering unit according to the invention, thereby preventing tools or pliers from closing due to accidental pressure and thus avoiding injury. The safety valve only releases the pressure passage when necessary.

[0015] Furthermore, it is stipulated that the safety valve can be operated purely mechanically. This has several advantages, especially that it does not require additional electronic components, does not occupy a very narrow structural space, and can utilize the gripping force originally used to grip the trigger unit.

[0016] This invention ensures that pressurized air is never interrupted without pressing the safety switch lever. This corresponds to a safer base position. Simultaneously, the tool's pressure cylinder reliably vents air in the base position. If the safety switch lever is pressed, the safety valve adjusts to close the venting and pressure is smoothly delivered to the pliers. Here, the pressure valve should automatically reset to a reliable pressure position without manual intervention, thereby automatically shutting off the tool and venting air. Attached Figure Description

[0017] Other technical features and advantages are illustrated in the following figures. The entire specification, claims, and drawings disclose the features of this application in specific embodiments and combinations. Those skilled in the art can also consider the technical features individually and combine them into other combinations or sub-combinations, thereby adapting the invention as defined in the claims to their needs or specific fields of application.

[0018] In the attached diagram:

[0019] Figure 1 A pneumatic tool constructed as pliers according to a first embodiment of the present invention is shown;

[0020] Figure 2 Showing the position in the base Figure 1 Valve of the tool in the middle;

[0021] Figure 3 Showing other locations Figure 2 The valve;

[0022] Figure 4a and Figure 4b Shown in a wider range Figure 2and Figure 3 The valve;

[0023] Figure 5a and Figure 5b A first longitudinal sectional view of the handle of the pneumatic tool according to the invention is shown; and Figure 6a and Figure 6b A second longitudinal sectional view of the handle of the pneumatic tool according to the present invention is shown. Detailed Implementation

[0024] Figure 1 A pneumatic tool 10, constructed as pliers according to a first embodiment of the present invention, is shown.

[0025] The pliers are designed for installing pipe clamps, hose spring clamps, locking rings, etc. Multiple pistons 14 are arranged in a row or series within the pressure cylinder 12.

[0026] A pressure medium connector 16 is provided at the rear end of the manually operable pneumatic pliers. The pressure medium connector allows the pliers to communicate with a pressure medium, such as compressed air, through a pressure line (not shown). The pressure medium inlet can be opened or the tool 10 can be vented by means of the safety switch lever 18 of the operating valve 22.

[0027] Each piston 14 has a passage through the piston rod to allow a pressurized medium to pass through. A radially outward-pointing discharge port is provided in the region at the front end of the piston rod. Pressurized air can be discharged through these discharge ports. The pressurized air drives the rear piston 14 forward. The passage of pressurized air through the passage in the rear piston rod is repeated in a similar manner or method.

[0028] A so-called wedge piston 24 follows the foremost piston 14 toward the pliers tool 20. A wedge-shaped feed mechanism is arranged on the front side of the wedge piston for operating the pliers head, or pliers tool 20. Driven forward by the wedge piston 24 with the aid of a pressure medium, the two jaws of the pliers tool 20, for example supported on pins, are driven to open in the rear region by the wedge-shaped surface advancing between the two rollers. Simultaneously, the two jaws of the pliers tool 20 are driven to close in the closing direction at the front side, for example, to clamp a hose spring clamp or to press an ear clamp by operating the pliers tool 20.

[0029] In addition, the pneumatic tool includes a handle 26, on which a safety switch lever 18 for operating the valve 22 is arranged. A printed circuit board with an electronic switching unit 38 is also provided in the handle 26, which sends a pressure request signal to the pressure source via a signal line in the pressure line.

[0030] Figure 2The diagram shows valve 22 in its base position, in which the connection between pressure medium connector 16 and pressure cylinder 12 of tool 10 is interrupted. Valve 22 includes a valve body 28 configured as a shaft ring, which is arranged on pressure supply connector pipe 30 and is available in the base position and at least one other position (see...). Figure 3 Activities between )

[0031] The pressure supply connector pipe 30 has a first internal hole 30a opening toward the pressure medium connector 16 and a second internal hole 30b opening toward the pressure cylinder 12, as well as radial first and second pressure passage holes 32a, 32b. The pressure passage holes 32a, 32b respectively communicate with the outer surface of the first or second internal holes 30a, 30b. Figure 2 In the basic position shown, the first pressure passage hole 32a leads into the pressure chamber 34 of the valve 22, and the second pressure passage hole 32b is freely exposed for venting.

[0032] Therefore, as the valve body 28 moves toward the base position, the pressure cylinder 12 exhausts gas through the second pressure passage hole 32b.

[0033] The inner surface of a valve body 28, movable on the pressure supply connector pipe 30 and configured as a shaft ring, together with the outer surface of the pressure supply connector pipe 30, forms a pressure chamber 34. Two axial end faces 34a and 34b of the pressure chamber 34 are formed by the inner surface of the shaft ring and have different areas. These different areas create different pressures acting in opposite directions, and the resultant force acts towards the end face 34b with the larger area. In other words, in… Figure 2 and Figure 3 The valve body 28 moves towards the base position, acting to the right. Therefore, the pressure applied to the pressure medium connector 16 causes the valve body 28 to move along the base position when the safety switch lever 18 is released. Figure 2 and Figure 3 The valve body 28 moves to the right to its base position without the user or other means applying any other force to it.

[0034] A sealing element 36 is provided on the inner edge of the outer surface of the pressure supply connector pipe 30 on the end faces 30a and 30b of the valve body 28, which seals the pressure chamber 34. In particular, the use of a sealing lip with an X-shaped profile, i.e., an O-ring or a quadrilateral ring, has the advantages of low adhesive friction and dynamic friction.

[0035] When the user releases the safety switch lever 18, for example, due to the user leaving, the valve 22 reliably returns to its base position by pressure without manual intervention (see [link to valve 22]). Figure 2At the same time, the pressure cylinder 12 exhausts air, thereby enabling the smooth and reliable removal of potentially stuck components, such as fingers, clothing, or other objects.

[0036] The different areas are achieved by the different outer diameters of the pressure supply connector pipe 30, and specifically, the outer diameter of the pressure supply connector pipe 30 on the side open toward the pressure cylinder 12 is larger than the outer diameter of the pressure supply connector pipe 30 on the side open toward the pressure medium connector 16. The areas with different outer diameters are separated by steps that are bridged by the shaft ring of the valve body 28.

[0037] Figure 3 The valve 22 is shown in one of the other positions, in which a connection is established between the pressure medium connector 16 and the pressure cylinder 12 of the tool 10. In this other position, both the first and second passage holes 32a and 32b open into the pressure chamber 34. Thus, a pressure connection is established from the pressure medium connector 16 through the pressure chamber 34 to the pressure cylinder 12.

[0038] By operating the safety switch lever 18, the valve 22 is actuated and thus opened, or rather, directed towards... Figure 3 The setting motion, wherein the valve body 28, constructed as a shaft ring, is in accordance with... Figure 3 Move to the left in the view. Keep valve 22 open by holding safety switch lever 18 (see...). Figure 3 If safety switch lever 18 is released at this time, for example due to a finger being stuck, the valve 22 will automatically close due to the continuous pressure (see...). Figure 2 ).

[0039] Because the pressure loading areas are different, a resultant force is formed for closing. The annular surface towards the base position is larger, which results in an automatic closing resultant force. This ensures that valve 22 is always closed under pressure.

[0040] When pressure is applied, valve 22 is therefore monostable, unlike a conventional 3 / 2-way valve which is bistable.

[0041] Figure 4a and Figure 4b Show a wider range Figure 2 and Figure 3 The valve. In Figure 4a and Figure 4b In one embodiment, a spring 36 is provided, which generates a restoring force that pushes the valve body 28 to a base position when the safety switch lever 18 is released, and acts in the same direction as the resultant force generated by the pressure. The spring 36 provides pressure during the valve body 28's reset process, thereby allowing the valve 22 to transition to a safer closed base position even under low or no pressure. However, embodiments without the additional spring 36 are also possible.

[0042] The pressure supply connector 30 is installed in an adapter 40 relative to the pressure supply hose (with integrated signal wiring). The axial front end of the adapter 40 forms a stop for the valve body 38. An O-ring or O-waist 42 for cushioning the stop is provided here.

[0043] Figure 5a and Figure 5b A first longitudinal section of the handle 26 of the pneumatic tool according to the invention is shown. The valve body 28 is provided with a ramp 44, on which a protrusion 46 connected to a safety switch lever 18 slides via an adapting ramp. The safety switch lever 18 is pivotally connected to the handle 26 via a hinge arranged at the rear end of the handle 26.

[0044] When gripping handle 26, the user moves safety switch lever 18 from the closed position (see...). Figure 5a Pivot inward to the open position (see) Figure 5b ), and the valve body 28 moves to the open position via the protrusion 46 and the ramp 44.

[0045] Figure 6a and Figure 6b A second longitudinal section of the handle 26 of the pneumatic tool according to the invention is shown. An angled switch boss 48, fastened to the valve body 28, operates a safety switch 50 arranged in the handle 26. This safety switch must be closed so that an electronic switch unit 38, arranged in the handle 26, can send a pressure request signal to a pressure source via a signal line in the pressure line. When the valve body 28 moves toward the open position, the switch boss 48 operates the safety switch 50 and closes its contacts, thereby satisfying the necessary condition for triggering the pressure request signal in the logic of the electronic switch unit 38. The switch boss 48 thus establishes a mechanical connection between the valve body 28 and the electromechanical safety switch 50, which allows the electronic switch unit 38 to monitor the valve 22.

[0046] List of reference numerals

[0047] 10 tools

[0048] 12 pressure cylinders

[0049] 14 Pistons

[0050] 16 Pressure Medium Connector

[0051] 18 Safety switch rod

[0052] 20 Pliers

[0053] 22 valves

[0054] 24 Wedge-shaped piston

[0055] 26 handles

[0056] 28 Valve body

[0057] 30 Connector Pipe

[0058] 32a, 32b Pressure passage holes

[0059] 34 Pressure Chamber

[0060] 36 Springs

[0061] 38 Switching Units

[0062] 40 accessories

[0063] 42 O-ring

[0064] 44 bevel

[0065] 46. ​​Protrusion

[0066] 48 Switch boss

[0067] 50 Safety Switch

Claims

1. A pneumatic tool, the tool comprising a handle (26), a valve (22), a safety switch lever (18) disposed on the handle (26) for operating the valve (22), and a pressure medium connector (16), wherein, The valve (22) includes a valve body (28) movable between a base position and at least one other position, wherein, in the base position, the connection between the pressure medium connector (16) and the pressure cylinder (12) of the tool is interrupted, and in the other positions, the connection between the pressure medium connector (16) and the pressure cylinder (12) of the tool is established. Its features are, The pressure cylinder (12) exhausts air as the valve body (28) moves toward the base position, and the pressure acting on the pressure medium connector (16) causes the valve body (28) to move toward the base position when the safety switch lever (18) is released. The valve body (28) is a movable ring on the pressure supply connector pipe (30), the inner surface of which, together with the outer surface of the pressure supply connector pipe (30), forms a pressure chamber (34). The pressure supply connector pipe (30) includes a first internal hole (30a) opening toward the pressure cylinder (12) and an opening toward the pressure... The medium connector (16) has an open second internal hole (30b) and first and second pressure passage holes (32a, 32b), which respectively connect the first internal hole and the second internal hole (30a, 30b) to the outer surface of the pressure supply connector pipe (30). In the basic position, the first pressure passage hole leads into the pressure chamber (34), and the second pressure passage hole is freely exposed for venting. In the other positions, both the first and second pressure passage holes (32a, 32b) lead into the pressure chamber (34).

2. The pneumatic tool according to claim 1, Its features are, The valve body (28) is constructed as a movable shaft ring on the pressure supply connector pipe (30), the inner surface of which together with the outer surface of the pressure supply connector pipe (30) forms a pressure chamber (34), wherein the two axial end faces (34a, 34b) of the pressure chamber (34) are formed by the inner surface of the shaft ring and have different areas.

3. The pneumatic tool according to claim 1, Its features are, The valve body (28) is a movable shaft on the pressure supply connector pipe (30), the inner surface of which together with the outer surface of the pressure supply connector pipe (30) forms a pressure chamber (34), wherein the outer diameter of the pressure supply connector pipe (30) on the side open toward the pressure cylinder (12) is greater than the outer diameter of the pressure supply connector pipe (30) on the side open toward the pressure medium connector (16).

4. The pneumatic tool according to claim 1, Its features , The pneumatic tool has a spring that generates a restoring force, which moves the valve body (28) to the base position when the safety switch lever (18) is released.

5. The pneumatic tool according to claim 1, Its features , The pneumatic tool has an electrical or electronic switching unit (38) which includes an electromechanical safety switch (50) mechanically connected to a valve body (28).

Images