device

Abstract

2. Device for separating gases from fluids, such as air from hydraulic oil, with a container (10) having at least two connection points (12, 14) for the alternating supply and discharge of fluid with a guide device (16) that increases the fluid path for a fluid flow between the connection points (12, 14) and causes a deflection of the direction of the respective fluid flow.

Description

[0001] The invention relates to a device for separating gases from fluids, such as air from hydraulic oil.

[0002] DE 10 2014 117 327 A1 discloses a steering system for a motor vehicle, with a hydraulic cylinder in which a piston movable in the axial direction of the hydraulic cylinder is arranged, wherein the hydraulic cylinder has first and second pressure chambers separated from one another by the piston, and wherein the hydraulic cylinder has a first stroke usable during operation of the steering system; a reversible hydraulic pump connected to the first pressure chamber of the hydraulic cylinder by a first hydraulic line and to the second pressure chamber of the hydraulic cylinder by a second hydraulic line; an oil reservoir for volume compensation of the hydraulic cylinder; and a device for venting the steering system, wherein the hydraulic cylinder has a second stroke located outside the first usable stroke for venting the steering system, wherein the device for venting the steering system is designed to fluidly connect the first pressure chamber of the hydraulic cylinder to the second pressure chamber of the hydraulic cylinder when the piston is positioned within a range of the second stroke of the hydraulic cylinder. The known solution aims to improve a "closed center" steering system so that it can be vented easily and reliably, wherein the device for venting the steering system is active during the filling process of the steering system.For this purpose, the piston of the hydraulic cylinder can be positioned in a specific range for the steering system venting mode, outside the usable stroke of the hydraulic cylinder for the respective steering movement. Only in this position of the piston is the device for venting the steering system released.

[0003] Based on this prior art, the invention is based on the object of improving the known device for separating gases from fluids, such as air from hydraulic oil.

[0004] This object is achieved by a device having the features of patent claim 1 in its entirety. The device according to the invention for separating gases from fluids, such as air from hydraulic oil, comprises a container having at least two connection points for the alternating supply and discharge of fluid, with a guide device that enlarges the fluid path for a fluid flow between the connection points and causes a redirection of the direction of the respective fluid flow. In this way, a permanent, in particular automatic, gas separation from fluids is achieved, which does not, as shown in the cited prior art, only provide for venting of a steering system during the filling process of the steering system. In particular, it is avoided that any air inclusions occurring in the hydraulic oil are no longer simply pushed back and forth during operation of the hydraulic device, but are actively discharged from the hydraulic oil.Accordingly, hydraulic circuits no longer need to be vacuum-filled in advance with great care, which is theoretically impossible because an absolutely vacuum-free space cannot be created in practice.

[0005] Since the guide device not only enlarges the fluid flow path in the reservoir, thus enabling improved gas separation, a partial pressure drop also regularly occurs in the area of ​​the direction reversal due to the deflection, which helps improve the separation of even finely dispersed air bubbles in the hydraulic oil. Furthermore, the flow is calmed and vortex formation occurs, which promotes the formation of air bubbles and thus prevents the further flow of dispersed air.

[0006] The guide device, which serves as a gas separation device, is integrated into the aforementioned container and, together with it, forms a tradable unit, allowing the device as a whole to be retrofitted into existing fluid circuits as a retrofit kit. In this respect, the container with the guide device serving as a gas separation device is a largely standardized component, eliminating the need for complicated adjustments to hydraulic cylinders regarding the free stroke for steering adjustment or venting.

[0007] In a preferred embodiment of the device according to the invention, the guiding or separating device consists of at least two, preferably concentrically arranged, pipe sections, of which an inner pipe section is placed within an outer pipe section and opens with one free end into one connection point and with its other free end into a deflection chamber enclosed by the other pipe section, which is closed in the direction of the other connection point and establishes a fluid-conducting connection between the deflection chamber and the interior of the container via a connection point. Thanks to this concentric arrangement, a reliable spatial separation of the respective upstream and downstream sides is achieved, and the flow deflection and the flow calming via an associated surface jump ensure reliable gas separation from the respective fluid flow passing through the container.

[0008] Preferably, the inner tube part forms a hollow-cylindrical guide body which passes through the container at one fluid connection point and is secured thereto. Preferably, the outer tube part also forms a hollow-cylindrical sleeve body which has a baffle plate on its closed side facing the other connection point and is closed off by one tube part on its opposite open side and secured to the inner wall of the container and / or to the inner tube part. Preferably, the deflection space is closed off by the inner tube part, with the connection between the deflection space and the interior of the container being provided at the height of the closure in question.While the oil on the respective upstream side still contains a high level of air, the air content in the oil decreases as the flow through the fluid guide device increases toward the respective downstream side, resulting in a significant depletion of gas from the oil. Thus, the separation occurs quasi-continuously and automatically during operation of the device.

[0009] In a further preferred embodiment of the device according to the invention, the container, the fluid connection points and the guide device are arranged concentrically to their respective longitudinal axes, and the guide device, starting from one fluid connection point in the direction of the other fluid connection point, ends approximately centrally or below the center in the container when viewed axially. This results in a structurally simple design of the device, which can therefore be implemented cost-effectively. This is also contributed to if the container is designed to be rotationally symmetrical to its longitudinal axis and, in particular, consists of a container as is usual for diaphragm accumulators, which is assembled from two housing halves in a pressure-tight manner and is regularly manufactured in very large quantities in mass production.

[0010] In a particularly advantageous manner, in both possible fluid flow directions through the container, the guide device interrupts the transport of an otherwise directly guided fluid transport between the fluid connection points with flow calming and flow deflection, so that a high separation rate of gas from the fluid is achieved in both directions.

[0011] In a further preferred embodiment of the device according to the invention, it is provided that, during operation, fluid originating from the fluid connection point other than the relevant upstream side is freed of gas by means of the separating or guiding device, which is deposited in an upper region in the container, that as it passes through the guiding device, fluid increasingly freed of gas is delivered to the fluid connection point serving as the downstream side, and that, during a backflushing process in which a volume flow reversal occurs between the upstream and downstream sides, the gas collected in the container passes into the environment via the other connection point, which can preferably be connected to a storage tank of a hydraulic system, via this storage tank. In this way, an effective discharge of gas collected in the container is achieved during container backflushing.The resulting gas separation from fluid is also referred to in technical terms as defoaming.

[0012] Particularly preferred is the use of a device as described above in a hydraulic brake system, which is preferably continuously vented, with the venting taking place automatically. Even if the hydraulic brake system is not used for a long period of time, effective venting takes place automatically from the start.

[0013] In the following, the device according to the invention for separating gases from fluid is explained in more detail using an exemplary embodiment according to the drawing. In this diagram, not to scale, the Fig. 1 a longitudinal section through the device as a whole; and Fig. 2 in the form of a hydraulic circuit diagram in a highly simplified representation the use of the device according to the Fig. 1 for a hydraulic braking system.

[0014] The Fig. Figure 1 shows the device for separating gases from fluids, such as air from hydraulic oil, comprising a container 10 having at least two connection points 12, 14 for the alternating supply and discharge of fluid. The device further comprises a guide device 16, which enlarges the possible fluid path for a fluid flow between the connection points 12, 14 and causes a redirection of the respective fluid flow, which will be explained in more detail below.

[0015] The guide device 16 consists of two concentrically arranged tube parts 18, 20, of which an inner tube part 18 is placed in an outer tube part 20 with a vertical orientation. The inner tube part 18 opens in the direction of view towards the Fig. 1, with its lower free end 22 into one connection point 12 and with its other upper free end 24 into a deflection chamber 26 which is enclosed by the outer tube part 20, which is closed in the direction of the other connection point 14 and otherwise establishes a fluid-carrying connection between the deflection chamber 26 and the interior 30 of the container 10 via a connection point 28.

[0016] The inner tube part 18 is received with its lower free end 22 in a shoulder-like recess 32 in a connecting body 34, which has an external thread 36 on the outer circumference in its free end region and is welded to the underside of the container 10 at the edge, for example in the form of a circumferential fillet weld 38, which can be applied, for example, by means of EB welding, laser welding, or resistance pressure welding. The use of other welding processes is possible.

[0017] The inner tube part 18 passes through a continuous central or container opening 40 on the underside of the container 10 at a radial distance. Furthermore, the inner tube part 18 is fixed by two snap rings 42, 44 relative to the inside of the outer tube part 20 or relative to the cylindrical inside of the connecting body 34. The connecting body 34 surrounds a hollow cylindrical central channel 46, forming the one connection point 12, which central channel 46 has a constant diameter and essentially merges without a step into a correspondingly designed central channel 48 of the inner tube part 18, which projects beyond the underside of the container 10.

[0018] The aforementioned connection point 28 in the outer tube part 20 consists of individual passage openings 50 in the form of bores, which penetrate a cylindrical wall of the outer tube part 20 diametrically opposite a longitudinal axis 52 of the device and establish a fluid-carrying connection between the deflection chamber 26 and the interior 30 of the container 10. All passage openings 50, of which the inner ones are partially covered by the inner tube part 18, lie on a common central plane transverse to the longitudinal axis 52 of the container 10 and have one and the same free cross-section.

[0019] Overall, the inner tube part 18 forms a hollow cylindrical guide body that passes through the container 10 at the fluid connection point 12 and is fixedly attached to the container 10. The outer tube part 20, on the other hand, forms a hollow cylindrical sleeve body that has a baffle plate 54 on its closed side facing the other connection point 14. On its opposite open side, the outer tube part 20 is closed by the inner tube part 18 and otherwise fixed at the bottom to the outer wall of the inner tube part 18, for example during the application of a weld seam (not shown).

[0020] In an alternative embodiment, which is also not shown, it is also possible to fix the outer tube part 20 at the bottom to the inner wall 56 of the container 10 in this area, in which case the central opening 40, as seen from the underside of the outer tube part 20, would then be covered in a fluid-tight manner by a weld seam (not shown) engaging in the remaining opening. The flat baffle plate 54 running transversely to the longitudinal axis 52 has the advantage that when a gas-containing fluid flow strikes from the other connection point 14, the separation of gas from the fluid flow is improved, for example because in the area of ​​the baffle plate 54 there is a sharp deflection of the impinging fluid flow, with a separation of gas from the fluid.

[0021] The deflection chamber 26 already mentioned has, according to the illustration, Fig. 1 has a tapered inner cone 58 which, arranged on the inside of the outer tube part 20, tapers conically in the direction of the impact plate 54. Otherwise, the inner cone 58 overlaps the upper free end 24 of the inner tube part 18 like a roof. Furthermore, the outer tube part 20 surrounds the inner tube part 18 with a constant diameter, and the corresponding part of the deflection chamber opens into the connection point 28 in the form of the passage openings, specifically in a region of a stepped, shoulder-like widening 59 of the inner tube part 18, which then comes into direct contact with the inner circumference of the outer tube part 20 with its outer circumference. In this respect, the deflection chamber 26 is therefore delimited by the inner tube part 18 and closed off in the direction of the one connection point 12.Furthermore, the fluid-carrying connection between the aforementioned deflection chamber 26 and the interior 30 of the container is established via the connection point 28 essentially at the height of the corresponding termination between the outer pipe part 20 and the inner pipe part 18.

[0022] Furthermore, the container 10 has, in the direction of view, Fig. 1, at its upper end, a further connecting body 60, which in turn is firmly or fluid-tightly connected to the top or outside of the container 10 via a fillet weld 62 comparable to the fillet weld 38. The further connecting body 60 also has an external connection thread 64 at its free end and is centrally penetrated by a central channel 66, which opens into the interior 30 of the container 10 via a stepped widening 67 and a further circular central opening 68 in the top of the container 10. The container 10, the fluid connection points 12, 14 and the guide device 16 are arranged with their respective center axes concentrically to the longitudinal axis 52 of the device. The guide device 16 opens along its baffle plate 54, starting from one fluid connection point 12 in the direction of the other fluid connection point 14, viewed in the axial direction below a container center 70 into the container 10.This arrangement results in particularly good gas separation performance, whereby the baffle plate 54 can also discharge directly along the vessel center 70 in an alternative embodiment (not shown). The vessel 10 is rotationally symmetrical to its longitudinal axis 52 and consists in particular of a vessel construction as is usual for diaphragm accumulators, consisting of two housing halves 72, 74 which are connected to one another in a pressure-tight manner along the vessel center 70, in particular welded together. Such diaphragm accumulator housings are shown, for example, with fiber winding, in DE 10 2008 062 837 A1. Diaphragm accumulators as such are generally produced in large quantities, so that their use for the guide or separation device in question is particularly cost-effective. Furthermore, the pressure vessel design results in a rigid, high-strength vessel wall construction.

[0023] Fluid can flow through the container 10 in both directions, i.e. from the further connection point 14 towards the one connection point 12 and vice versa, i.e. from one connection point 12 towards the further connection point 14. In the former case, the connection point 14 forms the so-called upstream side of the device and the connection point 12 the downstream side. In the case of the reversed upstream flow, i.e. when the direction of the fluid flow is reversed, the one connection point 12 forms the upstream side and the further connection point 14 forms the downstream side. Accordingly, fluid can flow through the container 10 in both possible fluid flow directions, wherein the guide device 16 interrupts an otherwise directly guided fluid transport between the two connection points 12, 14, wherein the aforementioned interruption in transport comprises both flow calming and flow diversion.The flow calming results from the extension of the path or the area jump for the transport of the fluid caused by the connection point 28 and the deflection chamber 26, and a deflection of the fluid flow by preferably 180° as soon as fluid exits the inner tube part 18 and is deflected by the inner cone 58 into the further deflection chamber 26, with another further right-angled deflection as soon as the fluid flow leaves the deflection chamber 26 via the passage openings 50 of the connection point 28 and exits into the comparatively larger interior 30 of the container 10. Comparable deflections occur in the other flow direction, i.e., starting from the connection point 28 in the direction of the deflection chamber 26 of the outer tube part 20 and further in the direction of the central channel 48 of the inner tube part 18.

[0024] During operation of the device, the gas-containing fluid supplied via connection point 14 is freed of gas by means of the guide device 16, so that connection point 14 represents the upstream side of the guide device 16, and connection point 12 the downstream side. The baffle plate 54 already contributes significantly to the accumulation or deposit of gas separated from the fluid on the upper side of the interior 30 of the container 10. Thanks to the guide device 16, the fluid arriving on the downstream side is largely freed of gas at the fluid connection point 12.During a backflushing process, in which the volume flow is reversed between the inflow and outflow sides, such that one connection point 12 now forms the inflow side and the other connection point 14 the outflow side, the gas accumulated in the container interior 30, which may also be present in foam form in conjunction with the fluid, is carried out via the fluid connection 14, and the gas thus discharged can then be separated from the device, which will be explained in more detail below. Starting from the baffle plate 54 of the outer tube part 20, however, there is a continuous gas separation the further the fluid flows downwards toward the connection point 28 with the passage openings 50, and also in the reverse direction.

[0025] The following is the use of the gas separation device after the Fig. 1 in the context of a hydraulic braking system according to Fig. 2. The Fig. 2 has a spring-loaded hydraulic brake cylinder 76, which is fluid-conductingly connected to one connection point 12 via a line 79 via an adjustable throttle or orifice 78. This fluid conduit opens out on the piston side 80 of the brake cylinder 76, which is delimited by a piston-rod unit 82. The spring-loaded piston-rod unit 82, with its rod portion, opens out of the housing of the brake cylinder 76 for the purpose of actuating a conventional mechanical brake. Furthermore, the upper or other connection point 14 of the reservoir 10 is connected via a hydraulic connecting line 83 to a magnetically actuated 3 / 2-way valve 84, which, in one valve position, establishes a pressure-conducting connection between a hydraulic pump 86 and this other connection point 14 of the reservoir 10. The hydraulic pump 86 is supplied with fluid from a storage tank 88.For the supply of the brake cylinder 76, the valve 84 takes its position in the . Fig. 2. A spring-loaded check valve 90 is connected between the hydraulic pump 86 and the valve 84. This check valve opens in the direction of the valve 84 and thus prevents any unwanted backflow of fluid toward the hydraulic pump 86. The corresponding supply circuit 92 is protected in the usual way by a pressure relief valve 94. The respective fluid lines 83, 79 from the valve 84 to the other connection point 14, as well as from the brake cylinder 76 via the throttle 78 to one connection point 12, are connected via a conventional piping that is screwed to the external threads 64 and 36 of the connection point 14 and 12, respectively, in the usual way.

[0026] If the hydraulic pump 86 is switched on, the brake cylinder 76 is actuated and the piston-rod unit 82 extends to actuate the mechanical brake against the effect of an energy storage device in the form of the compression spring 96 shown. Due to the Fig. 2 guide or separating device 16, not shown in detail, the gas separated in the container 10 is collected at its top in the direction of the other connection point 14, which can also take place in the form of a foam. If the valve 84 is now switched and takes up its Fig.2, a fluid connection exists between the interior 30 of the container 10 and a tank 98, which can also be part of the storage tank 88. In this switching position of the valve 84, the brake cylinder 76 is no longer subjected to braking pressure from the hydraulic pump 86 and, due to the action of the compression spring 96, returns to its non-actuated initial position, wherein fluid on the piston side 80 is expelled via the connection point 12 and the guide device 16 in the direction of the other connection point 14. In this case, the gas or foam stored in the container 10 is expelled from the container 10 via the valve 84 in the direction of the tank 98, which carries ambient pressure, so that the gas is permanently separated from the fluid in the tank 98.The brake system is then available for braking again, whereby the quasi-automatic venting can take place even if the brake system has been shut down for a longer period. Accordingly, the gas separation occurs via the separating and guiding ring device 16 in the reservoir 10 as soon as a braking operation is triggered within the scope outlined.

[0027] It is understood that the application of the gas separation device in braking systems is only exemplary and the described gas separation or isolation device can also be used for other hydraulic systems.

Claims

[1] Device for separating gases from fluids, such as air from hydraulic oil, with a container (10) which has at least two connection points (12, 14) for the alternating supply and discharge of fluid with a guide device (16) which enlarges the fluid path for a fluid flow between the connection points (12, 14) and causes a deflection of the direction of the respective fluid flow. [2] Device according to claim 1, characterized byin that the guide device (16) consists of at least two pipe parts (18, 20) which are preferably arranged concentrically to one another, of which an inner pipe part (18) is placed in an outer pipe part (20) and opens with one free end into one connection point and with its other free end into a deflection space (26) which is enclosed by the outer pipe part (20), which is designed to be closed in the direction of the other connection point (14) and which establishes a fluid-conducting connection between the deflection space (26) and the interior (30) of the container (10) via a connection point (28). [3] Device according to claim 1 or 2, characterized by that the inner tube part (18) forms a hollow cylinder-like guide body which passes through the container (10) at one connection point (12) and is fixed to this (12). [4] Device according to one of the preceding claims, characterized bythat the outer tube part (20) forms a hollow cylinder-like sleeve body which has a baffle plate (54) on its closed side facing the other connection point (14) and is closed on its opposite open side by the inner tube part (18) and is fixed to the inner wall of the container (10) and / or to the inner tube part (18). [5] Device according to one of the preceding claims, characterized by that the deflection space (26) is delimited by the inner pipe part (18) and that the connection between the deflection space (26) and the interior (30) of the container (10) is provided at the height of the relevant closure. [6] Device according to one of the preceding claims, characterized bythat the container (10), the fluid connection points (12, 14) and the guide device (16) are arranged concentrically to their respective longitudinal axes, and that the guide device (16), starting from one fluid connection point (12) in the direction of the other fluid connection point (14), ends approximately centrally or below or above a center (70) in the container (10) when viewed in the axial direction. [7] Device according to one of the preceding claims, characterized by that the container (10) is rotationally symmetrical to its longitudinal axis (52) and in particular consists of a container (10) as is usual for diaphragm accumulators, which is composed of two housing halves (72, 74) in a pressure-tight manner. [8] Device according to one of the preceding claims, characterized bythat in both fluid flow directions through the container (10) by means of the guide device (16) a transport interruption of an otherwise directly guided fluid transport between the fluid connection points (12, 14) with flow calming and flow deflection takes place. [9] Device according to one of the preceding claims, characterized bythat during operation, fluid originating from the other fluid connection point (14) than the relevant downstream side is freed of gas by means of the guide device (16), which is deposited in an upper region in the container (10), that as it passes through the guide device (16), fluid increasingly freed of gas is delivered to the one fluid connection point (12) serving as the downstream side, and that during a backflushing process, in which a volume flow reversal takes place between the upstream and downstream sides, the gas collected in the container (10) reaches the environment via the other connection point (14), which can preferably be connected to a storage tank (88, 98) of a hydraulic system. [10] Use of a device according to one of the preceding claims in the context of a hydraulic brake system which is to be vented, and in that the venting to that end takes place automatically.

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