Hydraulic switch and drill hammer

Abstract

The invention relates to a hydraulic switch (1) comprising a separation chamber (2) which has an inlet opening, a first outlet opening (21) and a second outlet opening (22), wherein the inlet opening is connected to an inlet channel (4) and the first and the second outlet opening (21, 22) are each connected to an outlet channel (51, 52) each of which has a first longitudinal portion (521, 511) and a second longitudinal portion (522, 512), wherein the first longitudinal portion (511, 521) has, proceeding from the outlet opening (21, 22), a cross-sectional area that increases as the length increases, wherein the hydraulic switch (1) furthermore contains a first and a second feedback channel (31, 32), the inputs (311, 321) of which are located in the respective second longitudinal portion (512, 522) of one of the outlet channels (51, 52) and the outputs (312, 322) of which open out at opposite sides of the inlet channel (4). The invention also relates to a drill hammer having such a hydraulic switch.

Description

[0001] The invention relates to a hydraulic switch with a separating chamber having an inlet opening, a first outlet opening, and a second outlet opening, wherein the inlet opening is connected to an inlet channel and the first and second outlet openings are each connected to an outlet channel. Hydraulic switches of this type can be used for the fluid actuation of an oscillating load, which can be, for example, a piston.

[0002] A hydraulic switch of this type is known from US 3,016,066. This known hydraulic switch has a separating chamber with an inlet opening. During operation of the hydraulic switch, a pressure-controlled actuator fluid is supplied to the inlet opening. The actuator fluid exits the separating chamber through one of the two opposing outlet openings. For this purpose, the Coand The effect is exploited, which causes the drive fluid to adhere to one wall of the separating chamber. A pulse applied via a feedback channel directs the drive fluid to the opposite boundary wall of the separating chamber, causing it to exit through the second outlet opening on the opposite side. This switching process can be repeated cyclically. The known hydraulic switch thus operates as an oscillator without any wear-prone mechanical switching elements. The fluid exiting the openings alternately can be used to operate oscillating fluid machines.

[0003] This known hydraulic switch, however, has several shortcomings. For example, the oscillation starts unreliably after standstill or when the volume flow supplied via the inlet opening begins. In some cases, it has been found that the oscillator runs unstably, i.e., the oscillation stops after a certain operating time, so that the drive fluid continuously leaks from a single outlet opening. Finally, the known hydraulic switch has a high pressure drop, which limits its possible applications. DE 15 66 290 A1 discloses a device and a method for mouth rinsing with a liquid.

[0004] Based on the prior art, the invention is therefore based on the objective of providing a hydraulic switch which starts reliably after standstill, runs stably, maximizes frequency and minimizes pressure loss.

[0005] The problem is solved according to the invention by a hydraulic switch according to claim 1 and a piston-driven consumer, for example a hammer drill according to claim 11. Advantageous embodiments of the invention are found in the dependent claims.

[0006] According to the invention, a hydraulic switch is proposed which includes a separating chamber. The separating chamber has an inlet opening on one side. At the inlet opening on the opposite side of the separating chamber, there is at least one first outlet opening and at least one second outlet opening. The separating chamber can have a substantially triangular base, such that the cross-section increases from the inlet opening to the outlet openings. The separating chamber can have a prismatic base shape, such that the boundary surfaces are flat. In other embodiments of the invention, the separating chamber can have a conical cross-section, i.e., the boundary walls are curved.

[0007] When the hydraulic switch is operated, any fluid, such as water, alcohol, glycol, or oil, is supplied to the separating chamber via the inlet. The operating fluid can be supplied to the separating chamber at any flow rate and slightly increased pressure to generate a sufficiently fast fluid jet at the inlet. Due to the Coand -effect: the propellant fluid supplied through the inlet opening adheres to a wall of the separating chamber and leaves the separating chamber through the first or second outlet opening.

[0008] Each outlet opening is followed by an outlet channel whose cross-section or cross-sectional area increases with length from the outlet opening. The increase in cross-sectional area can, for example, be linear or quadratic with the length of the first longitudinal section. The outlet channels can also have a polygonal or circular cross-section, as the Coand The effect does not come into play and therefore no longer requires flat surfaces. The diffusely shaped outlet channel serves to convert the previously kinetically converted energy of the incoming jet back into potential energy and slow it down. This increases the pressure again, allowing it to be used for the operation of the consumer.

[0009] When the hydraulic switch is operated, the fluid column of the drive fluid, directed into an outlet opening, is subjected to a switching pulse. This causes the jet of incoming fluid to adhere to the opposite wall of the separating chamber and thus be directed into the opposite outlet opening and the associated outlet channel. As soon as the operated device reaches its end position, the water column is subjected to another switching pulse, so that it is directed back over the opposite wall of the separating chamber into the original outlet opening. This switching process occurs cyclically and can generate an arbitrarily adjustable frequency depending on the selected parameters.

[0010] According to the invention, a first and second feedback channel are available for generating the switching pulse. The inputs of these channels are located in the lower longitudinal section of one of the outlet channels, and their outputs terminate on opposite sides of the inlet channel. Compared to known switches whose feedback channels begin further upstream in the outlet channels, it has been shown that the lower positioning in the lower longitudinal section of the outlet channels results in a stronger switching pulse that can be transmitted with less loss, despite the greater length of the feedback channels. This makes the switching operations of the hydraulic switch more reliable, resulting in more stable operation and fewer interruptions during switching. Comparative tests have shown that extending the feedback channels and positioning them lower in the second longitudinal section of the outlet channels can amplify the switching pulses by up to 30%.

[0011] One possible application for the described hydraulic switch could be, for example, a conventional surface or underground drilling hammer, which can be used, for instance, for drilling hard rock in mining, geothermal energy, or oil and gas exploration. Such a drilling hammer can have a piston / cylinder pairing in which a freely oscillating piston within the cylinder generates impact energy that is transferred to a drill bit and serves to crush the rock. For this purpose, the piston is alternately subjected to a drive fluid from its underside and its upper side, so that the piston is cyclically lifted from a lower end position and then accelerated downwards from the upper end position.Connecting an upper and a lower port of the cylinder to one of the outlet channels of the hydraulic switch ensures that the piston is cyclically supplied with the drive fluid from above and below, causing it to oscillate. Compared to known hydraulic switches, the hydraulic switch according to the invention offers the advantage of stable and reliable operation and reliable start-up of the piston or the connected actuator. Compared to known mechanical switching elements, the hydraulic switch according to the invention offers the advantage of low-wear operation without moving parts. This allows the use of drive fluids that are abrasive due to dispersed particles, such as dirty water or cleaning fluids.

[0012] In some embodiments of the invention, at least one separation edge can be arranged in the wall of the separating chamber, the distance of which from the inlet opening determines the mode of action of the Coand. -effect is influenced. In the hydraulic switch according to the invention, this lies between approximately 40% and approximately 60% of the length of the separating chamber. In this way, the separation edge is arranged further upstream than in known hydraulic switching elements. This feature has the effect that the Coand The effect of the incoming jet is stabilized, causing it to be drawn more strongly against the inner wall of the separating chamber. This stabilizes the flow, allowing the hydraulic switch to operate more reliably and preventing the oscillation from abruptly stopping. The height of the separation edge above the wall of the separating chamber determines the resulting negative pressure.

[0013] In some embodiments of the invention, the hydraulic switch can further comprise at least a first drain channel and a second drain channel, wherein the first drain channel originates in the upper longitudinal section and above the feedback channel of the first outlet channel, and the second drain channel originates in the upper longitudinal section and above the feedback channel of the second outlet channel. According to the invention, it is proposed that in this case, the drain channel and the outlet channel enclose a point that is as acute as possible. This point can be between approximately 25° and approximately 50°. The drain channels serve to discharge the drive fluid ejected during the counter-movement of the consumer without affecting the flow exiting the separating chamber.The steeper arrangement of the outlet channels, compared to known hydraulic switches, offers the advantage that the drive fluid exiting the separating chamber reliably follows the outlet channel along its entire length and not through the Coand. The effect is deflected into the drain channel. Thus, the geometry of the outlet channels according to the invention contributes to the reliable operation of the hydraulic switch.

[0014] In some embodiments of the invention, the cross-sectional area of ​​the drain channels can range from approximately 5 mm² to approximately 80 mm². By selecting the cross-sectional area of ​​the drain channels, the maintained pressure, i.e., the ratio of the outlet pressure at the end of the outlet channels to the inlet pressure in the inlet channel, can be influenced within wide limits, allowing the hydraulic switch to be adapted to the requirements of a downstream, hydraulically driven device. The cross-sectional area of ​​the outlet determines the back pressure during the filling of the piston chambers. In some embodiments, the openings can also have different cross-sectional areas if the consumer exhibits asymmetrical pressure losses, for example, due to connecting channels of varying lengths.

[0015] In some embodiments of the invention, an inlet filter can be arranged at the inlet of the first and / or second feedback channel. Such an inlet filter prevents the feedback channel from becoming clogged, for example by dispersed particles, when dirty water is used as the drive fluid. This feature can thus increase the reliability of the hydraulic switch.

[0016] According to the invention, the hydraulic switch comprises a base plate and a cover plate, wherein a plurality of fitting elements are spaced apart between the base plate and the cover plate, such that these spaces between the fitting elements form at least the separating chamber, the inlet channel, the first and second outlet channels, the first and second feedback channels, and at least two drain channels. Such a design of the hydraulic switch has the advantage that the fitting elements can be manufactured separately. This increases the design versatility of the hydraulic switch, so that the geometry of the switch, which influences its performance, can be adjusted within wide limits. In addition, the inner surfaces of the hydraulic switch are prepared for coating or other applications during the manufacturing process prior to final assembly.hardening process accessible so that the inner surface of the separating chamber, the inlet channel, the first and second outlet channels, the first and second feedback channels and / or the optional drain channels can be at least partially hardened and / or coated with a wear-resistant layer.

[0017] In some embodiments of the invention, a wear-resistant layer may comprise a layer of diamond-like carbon with or without metal doping. In other embodiments of the invention, the wear-resistant layer may contain or consist of a carbide or a nitride, for example, titanium nitride and / or hard chromium and / or silicon nitride. The wear-resistant layer may be applied in a manner known per se by plasma spraying, flame spraying, thermal evaporation, magnetron sputtering, or other thin-film processes known per se.

[0018] In some embodiments of the invention, the separating chamber between the first outlet opening and the second outlet opening can be convex. Compared to known embodiments of a hydraulic switch in which the separating chamber between the outlet openings is concave, the geometry according to the invention results in more stable operation and a lower pressure loss at the end of the outlet channels.

[0019] In some embodiments of the invention, the distance between the base plate and the cover plate, and thus the depth of the channels between them, can be varied. The thickness of the fitting elements directly influences the cross-section of the hydraulic switch, so that the relationship between pressure and volume can be adapted within wide limits to the requirements of the device operated by the hydraulic switch. The pressure across the hydraulic switch decreases with increasing channel depth.

[0020] In some embodiments of the invention, the inlet channel can have a width of approximately 2.05 mm. This allows the pressure drop in the inlet channel to be adjusted within wide limits. This dimension also determines the velocity of the incoming jet and thus the stability of the hydraulic switch.

[0021] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention. This will show Figure 1a shows a hydraulic switch according to a first embodiment not according to the invention with the cover plate removed. Figure 1b shows the hydraulic switch according to the first embodiment in section. Figure 2 shows an embodiment of an input of a feedback channel. Figure 3a shows a hydraulic switch according to a second embodiment according to the invention with the cover plate removed. Figure 3b shows the hydraulic switch according to the second embodiment in section. Figure 3c shows individual parts of the hydraulic switch according to the second embodiment. Figure 4 shows the ratio of volume flow rate to inlet pressure for different inlet channel widths. Figure 5 shows the pressure against the volume flow rate as a function of the milling depth or the distance between the base plate and the cover plate. Figure 6 shows the pressure ratio of a working fluid between the inlet channel and the outlet of the hydraulic switch.Figure 7 shows the influence of the position of the breaking edge on the switching frequency as a function of the input pressure.

[0022] Based on the Figure 1 A first embodiment of a hydraulic switch, not according to the invention, is explained in more detail. The hydraulic switch 1 consists of a piece of material 15 which is provided with milled recesses. The piece of material 15 has a flat front surface which can be closed with a cover plate 11 after the separating chamber and the other components of the hydraulic switch have been manufactured by milling recesses into the block of material 15.

[0023] Naturally, the hydraulic switch 1 can be manufactured not only by milling, but also by an additive manufacturing process, in particular by layered application and subsequent melting of a metallic powder. In other embodiments not according to the invention, the hydraulic switch can be manufactured at least in its raw form by means of a casting process, which can subsequently be further processed by optional machining.

[0024] An optional seal can be inserted between the material block 15 and the cover layer 11 to prevent liquid from escaping from the gap formed between the material block 15 and the cover layer 11.

[0025] The cover layer 11 can be fastened to the material block 15 by screws (not shown). In other embodiments, the cover layer 11 can also be joined by gluing or welding, which can simultaneously create a seal. In still other embodiments, the cover layer 11 can also be joined by one or more clamping elements. The hydraulic switch 1 has a separating chamber 2, which contains a Figure 1aThe separating chamber 2 has an inlet opening as shown above, and at least one first outlet opening 21 and one second outlet opening 22 opposite it. The inlet opening of the separating chamber 2 is connected to an inlet channel 4. The inlet channel 4 has a connector 40 at its end opposite the inlet opening of the separating chamber 2, which may, for example, be provided with a screw thread. When the hydraulic switch is in operation, the connector 40 can be connected to a hose through which a drive fluid can be supplied. The drive fluid may, for example, contain or consist of water, oil, glycol, or alcohol. Abrasive particles may be dispersed in the drive fluid.

[0026] The propellant fluid supplied to the separating chamber via inlet channel 4 settles due to the Coand -effect attaches to a wall 20 of the separation chamber 2 and thereby enters the first or the second outlet opening 21 or 22.

[0027] Each outlet opening is followed by an outlet channel 51 and 52. Each outlet channel has a first longitudinal section 511 and 521. In the first longitudinal section 511 of the first outlet channel 51, the cross-sectional area of ​​the outlet channel increases with length, starting from the first outlet opening 21 of the separating chamber 2. Similarly, the cross-sectional area of ​​the second outlet channel 52 increases in its first longitudinal section 521, starting from the second outlet opening 22 of the separating chamber 2. This increase in cross-sectional area can be linear or quadratic, for example. A second longitudinal section 512 and 522 follows the first longitudinal section 511 and 521, in which the respective outlet channel has a constant or nearly constant cross-sectional area. At the end of the second longitudinal section 512 and 522 of the outlet channels 51 and 52, respectively, there is an outlet opening 61 and 62.When the switch is operated, the drive fluid exits alternately from the outlet openings 61 and 62 and can be supplied to a tool, for example a hammer drill.

[0028] The cross-section of the outlet channels can be polygonal or round. If the separating chamber, the inlet channel, and the outlet channels are produced by milling the material block 15, a square or rectangular cross-section is particularly suitable, as it is easily controllable by the milling depth and width and can be adapted to different applications of the hydraulic switch.

[0029] The inlet 311 of a first feedback channel 31 is located in the lower longitudinal section of the first outlet channel. The end 312 of the first feedback channel 31 is located in the separating chamber 2. In the illustrated embodiment, the end 312 of the first feedback channel 31 is arranged at the end of the inlet channel 4. In other embodiments of the invention, the end 312 can also be arranged further downstream within the separating chamber 2, for example in a region between approximately 5% and approximately 20% of the length of the separating chamber 2 measured in the flow direction.

[0030] Similarly, opposite the second longitudinal section 522 of the second outlet channel 52 is the inlet 321 of a second feedback channel 32. The end 322 of the second feedback channel 32 is also located in the separating chamber 2 opposite the end 312 of the first feedback channel 31.

[0031] When the hydraulic switch is operated, a pressure fluctuation in the outlet channel, caused by the consumer reaching its end position, is introduced as a switching pulse into the respective feedback channel 31 or 32. At its end, 312 or 322 acts on the fluid jet coupled in via the inlet channel 4, causing it to detach from the wall 20 of the separating chamber 2 and be directed into the opposite outlet opening. A pressure peak then arises again in the outlet channel, which is transmitted as a switching pulse via the respective feedback channel 31 or 32 into the separating chamber 2, so that the drive fluid is directed back into the original outlet opening. In this way, a stable oscillation of the supplied drive fluid is created without the use of moving parts, and it exits alternately through the outlet openings 61 and 62.The drive fluid can thus be used to operate one or more hydraulic devices and drive, for example, the oscillating piston of a rotary hammer. In this case, the first outlet opening 61 is connected to the lower end of the cylinder, and the second outlet opening 62 is connected to the upper end of the cylinder, so that the piston inside the cylinder is alternately acted upon from above and below by the drive fluid, causing it to oscillate and exert impact energy on a drilling tool connected to the rotary hammer.

[0032] In the described application, the drive fluid ejected by the drill hammer during the respective counter-movement reaches the first and second outlet channels 51 and 52 via the respective outlet openings 61 and 62 in a backflow. To prevent disruption of the drive fluid flow exiting the hydraulic switch and to empty the opposite filled chamber, each outlet channel has a corresponding drain channel 71 and 72, which carries away the drive fluid ejected from the piston. For this purpose, the first drain channel 71 can be located in the first longitudinal section 511 of the first outlet channel 51. The second drain channel 72 can be located in the first longitudinal section 522 of the second outlet channel 52, with the respective drain channels 71 and 72 and the first longitudinal section 511 or 521 of the respective outlet channels 51 and 52 forming an angle between approximately 25° and approximately 50°.This steeper arrangement of the drain channels, compared to the state of the art, prevents the drive fluid from being discharged directly from the respective outlet opening 21 or 22 into the drain channels 71 or 72 without reaching the outlet openings 61 or 62, and at the same time facilitates the outflow of the used fluid during the counter-movement.

[0033] The milling depth within the material block 15 can be varied arbitrarily in some non-inventive embodiments. As shown below with reference to the Figure 5 As will be explained, the milling depth influences the pressure applied to the outlet openings 61 and 62, so that the hydraulic switch can be adapted to its future use during its manufacture.

[0034] Based on the Figure 2 A further enlarged section of hydraulic switch 1 is shown. Figure 2shows the first outlet channel 51 and part of its first longitudinal section 511 and its second longitudinal section 512. As shown from Figure 2 As can be seen, an inlet filter 35 is located at the inlet 311 of the first feedback channel 31. This filter prevents particles from the drive fluid from entering and clogging the feedback channel 31. This increases the reliability of the hydraulic switch because it reduces the risk of the drive fluid oscillating to stop. The inlet filter 35 can contain a porous material, such as a polymer foam or a metal foam. In other embodiments of the invention, the inlet filter 35 can be, or contain, a braid, a knitted fabric, or a nonwoven or tangled fiber material made of a metal or plastic.

[0035] Based on the Figure 3A second embodiment of the hydraulic switch 1 according to the present invention will be explained in more detail. Identical components of the invention are designated with the same reference numerals, so the following description is limited to the essential differences.

[0036] How Figure 3b As shown, the hydraulic switch according to the second embodiment differs from the one in Figure 1The first embodiment shown differs essentially from the second embodiment by a modified mechanical design. According to the second embodiment, the hydraulic switch comprises a base plate 10 and a cover plate 11, with a plurality of fitting elements 151, 152, 153, 154, and 155 arranged between the base plate and the cover plate. The thickness of these fitting elements, and thus the distance between the base plate and the cover plate 11, is determined by the milling depth of the first embodiment described above. An optional seal can be inserted between the fitting elements and the cover plate 11 or the base plate 10 to prevent unwanted fluid leakage. The fitting elements 151, 152, 153, 154, and 155, the cover plate 11, and the base plate 10 can be connected to one another by positive locking, by material locking, by clamping, or by screwing.

[0037] Figure 3ashows the base plate 10 and the fitting elements 151, 152, 153, 154 and 155 with the cover plate 11 removed. Figure 3c shows a portion of the fitting elements independent of the base plate 10 and with a larger spacing. As can be seen from the Figures 3a and 3cAs can be seen, the fitting elements 151, 152, 153, 154, and 155 are designed such that they can be arranged at intervals on the base plate 10, and these intervals form at least one separating chamber 2, one inlet channel 4, one first and second outlet channel 51 and 52, and one first and second feedback channel 31 and 32. In the illustrated embodiment, the fitting elements 151, 152, 153, 154, and 155 also optionally form first and second discharge channels 71 and 72. The fitting elements 151, 152, 153, 154, and 155 in the respective depicted forms can be manufactured, for example, by machining, by primary forming, or by an additive manufacturing process. The fitting elements 151, 152, 153, 154 and 155 preferably consist of a metal or a plastic, in particular of steel or stainless steel. Advantageous about the in Figure 3The second embodiment shown is particularly advantageous because the inner surfaces of the separating chamber, inlet channel and outlet channels are accessible during the manufacturing process, allowing these surfaces to be provided with an optional coating that adjusts the surface quality to a desired target value in order to achieve the Coand -effect of the drive fluid on the wall 20 of the separating chamber 2. Alternatively or additionally, the coating can be a wear-reducing coating, which increases the service life of the hydraulic switch. Finally, the coating can have friction-reducing properties, so that the pressure loss of the drive fluid as it passes through the hydraulic switch is reduced. Finally, the modular design of the second embodiment of the hydraulic switch allows for easy repair by replacing individual fitting elements 151, 152, 153, 154 and 155.

[0038] The hydraulic switch according to the invention has geometric parameters whose dimensions have a far-reaching impact on performance. According to the invention, relationships have been identified which can be approximated using cubic planes, so that the influence of the geometry on the behavior of the hydraulic switch can be predicted and the hydraulic switch can be optimized for the intended application without having to carry out time-consuming test series.

[0039] Figure 4 The graph shows the expected inlet pressure p at the beginning of the inlet channel on the abscissa and the volume flow rate V of the drive fluid on the ordinate. The expected inlet pressure depends largely on the cross-sectional area at the narrowest point of the inlet channel 4. Shown are pV curves for six different inlet channel widths at constant milling depth.

[0040] Thickness of the fitting pieces. The respective widths of the inlet channel 4 and the outlet channels 71 and 72 for the different measurement curves are summarized in the following table: curve Width b at the inlet channel Width v at the drainage channel A 0,52 3,44 B 3,26 3,77 C 2,71 3,12 D 2,35 4,06 E 2,07 2,81 F 1,87 3,72

[0041] The corresponding plane equation for the width b of the inlet channel 4 enables the determination of the pressure at different volume flows within the investigated measuring range: p V b = 0 , 00422 ⋅ V 2 + 9 , 02262 ⋅ b 2 − 0 , 31560 ⋅ V ⋅ b + 1 , 60487 ⋅ V − 36 , 53840 ⋅ b + 0 , 30664

[0042] This relationship applies to a flow rate of 60 l / min to 140 l / min and to an inlet channel with a width of 1.5 to 4 mm. The deviation has been shown to be less than 5%.

[0043] How Figure 5As shown, a similar relationship can be established for the milling depth t of the entire geometry. The milling depth also primarily determines the cross-sectional area of ​​the inlet channel 4, but it also affects the overall flow cross-section of the hydraulic switch. The ratio of the measured inlet pressures p when the milling depth is doubled from 10 mm (curve A) to 20 mm (curve B) is approximately 0.36. This ratio remains constant over the entire measuring range, which explains why curves A and B are so similar. Figure 5 diverge further and further with increasing volume flow.

[0044] The corresponding equation for the dependence of the inlet pressure p on the milling depth t and the volume flow rate V is: p V t = 0 , 00334 ⋅ V 2 + 0 , 01941 ⋅ t 2 − 0 , 01974 ⋅ V ⋅ t + 0 , 29973 ⋅ V − 0 , 31235 ⋅ t − 0 , 04695

[0045] This equation also applies to a flow rate between 60 l / min and 140 l / min and a milling depth of 5 mm to 30 mm. It has been shown that the deviation of the actual measured values ​​from the predicted values ​​is less than 7%.

[0046] The cross-sectional area of ​​the first and second drainage channels 71 and 72 influences the pressure loss or the actual pressure that can be measured at the outlet openings 61 and 62. This is shown in Figure 6 The inlet pressure is plotted on the abscissa and the average pressure loss on the ordinate. Six curves are shown again for different widths of the outflow channels 71 and 72 and the width b of the inlet channel 4, as follows: curve Width b at the inlet channel Width v at the drainage channel A 2,07 2,81 B 2,71 3,12 C 3,52 3,44 D 1,87 3,72 E 3,26 3,77 F 2,36 4,06

[0047] The relationship between inlet pressure and outlet pressure can be modeled as follows: p in p out V v = 0 , 00026 ⋅ V 2 − 1 , 15189 ⋅ v 2 + 0 , 001194 ⋅ V ⋅ v − 0 , 033860 ⋅ V + 8 , 48938 ⋅ v − 8 , 41896

[0048] This relationship applies to a flow rate of 60 l / min to 140 l / min and to a width of the drainage channels 71 and 72 between 2.5 mm and 4.5 mm. It has been shown that the deviations are less than 10%.

[0049] All described plane equations intersect the origin of the coordinate system, which is physically valid, since no pressure can be expected if there is no volume flow.

[0050] Figure 7This explains the influence of the position of the breaking edge 25 in the wall 20 of the separating chamber 2. The inlet pressure is shown on the abscissa and the switching frequency of the hydraulic switch on the left ordinate for two different positions of the breaking edge. Curve C shows the measured values ​​for a breaking edge located approximately in the middle of the separating chamber 2. Curve D shows the measured values ​​for a breaking edge 25 located, in a manner known per se, at the lower end of the separating chamber 2. The comparative example shows that the arrangement of the breaking edge 25 according to the invention, approximately in the middle of the separating chamber 2, can enable a higher switching frequency and more stable switching operations.

[0051] Furthermore, it shows Figure 7The inlet pressure on the abscissa is plotted against the maximum force generated by the drive fluid at the outlet openings 61 and 62 on the right ordinate. Curve A shows the force curve against the inlet pressure when the separating chamber 2 has a shear edge 25 located approximately in the center of the separating chamber 2. Curve B shows the maximum force curve for a shear edge 25 located at the end of the separating chamber 2 in a manner known per se. At least for an inlet pressure between approximately 25 and approximately 60 bar, the arrangement of the shear edge in the separating chamber according to the invention results in a higher pressure of the drive fluid at the outlet, so that a higher drive power can be transmitted to a drill hammer connected to the hydraulic switch.

[0052] Naturally, the invention is not limited to the embodiments shown. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Where the claims and the foregoing description define "first" and "second" embodiments, this designation serves to distinguish between two similar embodiments without establishing any hierarchy.

Claims

1. Hydraulic switch (1) comprising a separation chamber (2) which has an inlet opening, a first outlet opening (21) and a second outlet opening (22), the inlet opening being connected to an inlet channel (4) and the first and second outlet openings (21, 22) being each connected to an outlet channel (51, 52) which each have a first longitudinal portion (521, 511) and a second longitudinal portion (522, 512), the first longitudinal portion (511, 521) having, proceeding from the outlet opening (21, 22), a cross-sectional area that increases as the length increases, and the second longitudinal portion (512, 522) having a constant cross-sectional area, the hydraulic switch (1) further containing a first and a second feedback channel (31, 32), the inputs (311, 321) of which are located in the respective second longitudinal portion (512, 522) of one of the outlet channels (51, 52) and the outputs (312, 322) of which open out at opposite sides of the inlet channel (4), the hydraulic switch containing a base plate (10) and a cover plate (11), characterized in that a plurality of fitting members (15, 151, 152, 153, 154, 155) are inserted at a distance from one another between the base plate (10) and the cover plate (11) so that these distances form at least the separation chamber (2), the inlet channel (4), the first and second outlet channels (51, 52), the first and second feedback channels (31, 32) and optional drainage channels (71, 72).

2. Hydraulic switch according to claim 1, characterized in that at least one tear-off edge (25) is arranged in the wall (20) of the separation chamber (2), the distance of which from the inlet opening can be varied and is between approximately 40% and approximately 60% of the length of the separation chamber (2) in the hydraulic switch.

3. Hydraulic switch according to claim 1 or 2, further containing a first drainage channel (71) which proceeds in the first longitudinal portion (511) of the first outlet channel (51) and a second drainage channel (72) which proceeds in the first longitudinal portion (522) of the second outlet channel (51), wherein the drainage channel (71, 72) and the first longitudinal portion (511, 521) of the respective outlet channel (51, 52) form an angle between approximately 25° and approximately 50°.

4. Hydraulic switch according to claim 3, characterized in that the cross-section of the drainage channels (71, 72) is between approximately 5 mm2 and approximately 80 mm2.

5. Hydraulic switch according to any one of claims 1 to 4, characterized in that an input filter (35) is arranged at the input (311, 321) of the first and / or second feedback channel (31, 32).

6. Hydraulic switch according to claim 1, characterized in that the distance between the base plate (10) and the cover plate (11) is between approximately 5 mm and approximately 30 mm and can be adjusted according to the desired volume flow.

7. Hydraulic switch according to any one of claims 1 to 6, characterized in that the inner surfaces of the separation chamber (20), the inlet channel (4), the first and second outlet channels (51, 52), the first and second feedback channels (31, 32) and / or the optional drainage channels (71, 72) are at least partially hardened and / or coated with a wear protection layer.

8. Hydraulic switch according to any one of claims 1 to 7, characterized in that the separation chamber (2) is convexly shaped between the first outlet opening (21) and the second outlet opening (22).

9. Hydraulic switch according to any one of claims 1 to 8, characterized in that the inlet channel (4) has a width of approximately 2.05 mm or can be varied depending on the desired inflow velocity.

10. Hydraulic switch according to claim 7, characterized in that the wear protection layer contains and / or consists of DLC and / or TiN and / or Cr and / or SiN.

11. Piston-driven consumer, for example a drill hammer, having an impact mechanism and a hydraulic switch (1) according to any one of claims 1 to 10.

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