DE3150117A1 - Flow-rate regulator for liquid and/or gaseous materials - Google Patents

Abstract

The invention relates to a hydrostatic or aerostatic bearing having a device which is connected in the bearing medium supply line to the respective bearing pocket for varying the medium flow as a function of the pressure difference between the input pressure and the output pressure corresponding to the pocket pressure, in the sense of increasing the flow rate when the pressure difference becomes smaller, i.e. when the pocket pressure increases. A housing chamber which is bounded by an elastic membrane is connected on the one hand to the medium input and on the other hand to the medium output and, in between, contains a variable flow resistance which is formed by a central region of the membrane and of the mouth of a housing opening located opposite the membrane. The bending of the membrane determines the magnitude of the flow resistance. The housing opening, whose mouth is a component of the variable resistance, forms the medium output. Arranged on the input side of the housing chamber is a bias resistance, which is fixed or adjustable from the outside, and reduces the input pressure, in front of which the medium input is connected to the membrane side opposite the medium output, so that the central membrane region is subjected to the input pressure on the one side and to the output pressure on the other side, and the outer region of the membrane surrounding the central membrane region is subjected to the input pressure on the one side and to the reduced input pressure on the other side.

Description

Flow regulator for liquid and / or gaseous

Fabrics.

The invention relates to a flow regulator for liquid and or or gaseous substances with a solid or external through which the main stream flows adjustable flow resistance and one through the flow resistance on this prevailing pressure difference acted upon membrane, which depends on this pressure difference a second, changeable, also from the substance to be regulated flow resistance changed so that the flow rate is independent on the pressure difference between inlet and outlet constant or almost constant or is changed in a desired manner.

The flow regulator should be used generally for regulation of flow rates of liquid and / or gaseous substances, in particular of Substances without lubricating properties and or or aggressive substances as well as for regulation the amount of material for the supply of hydrostatic or aerostatic bearings 0 The purpose of the invention is to provide a flow regulator which is small in size and can be built cheaply, works hysteresis-free and wear-free, also at least can regulate slightly soiled substances and its flow depending on the dimensions with increasing differential pressure via the flow regulator alternatively as with known ones Volume control increases slightly, remains constant or almost constant or slightly or falls sharply, the latter property being particularly suitable for the supply of the Storage pockets for hydrostatic or aerostatic storage is advantageous known flow regulators, the differential pressure over a fixed or externally adjustable flow resistance regulated by differential pressure regulator, for which uses a precise piston sliding in a precisely machined bore Such flow regulators and their function are entering studies on throttle valves for hydraulic oil controls on machine tools (2nd part), Author Hans Schlayer from Das Industrieblatt, Vol. 62 (1962) NrO 5, page 275 - 286.

Flow regulator for liquid and / or gaseous substances Next is in "Machine Tools" Volume 2, author Manfred Weck, VDI-Verlag, page 142 - 144 describes the use of a membrane to build a load-dependent throttle, Since this throttle is only used to compensate for different loads from hydrostatic Bearings are used and not to regulate the differential pressure across a Control resistance, the statements made in the above book are related to the Protection of the use of a membrane for differential pressure control within a Flow regulators are not in the way of the known flow regulators described above - subject to hysteresis due to piston friction - the substance to be controlled must be of a minimum have a lubricating effect - the substance must be well filtered - due to the relative large mass of the control piston and the large control travel occur in the event of a sudden change the differential pressure between inlet and outlet and at the start of flow (start-up) Discontinuities (starting jump) - depending on the purity and lubricating effect of the controlled Substance, there is a risk of the control piston seizing up and thus the danger the destruction of the volume regulator and possibly downstream systems - the flow rate of such regulators decreases with falling differential pressure across the regulator due to the spring characteristic of the differential pressure spring - due to the necessary precise production of the bore and the control piston for the differential pressure control such regulators are relatively expensive - and relatively large.

The invention is based on the object of a flow regulator to create, which - works almost hysteresis-free and wear-free - fabrics can regulate without any lubrication effect - at least less susceptible to soiled Substances like previously known flow rate regulators - extremely short settling times and has almost no approach jump Flow regulator for liquid and / or gaseous substances are not due to the insufficient lubricating effect of the substance to be controlled or contaminated substances wear out or through seizure of the piston can fail totally ° one of the pressure difference between inlet and Output almost independent or one that increases in a defined manner with increasing differential pressure or has a sloping flow - cheap to manufacture is to be built small can.

According to the invention, this object is achieved in that the Rege treatment the differential pressure # p12 = P1 - Pl (see Fig. 1) on the amount of substance to be controlled Flow resistance, fixed or externally adjustable (1) (see Fig. 1) an elastic membrane (2) is inserted, which is loose near its edge rests on a membrane carrier (3) (see Fig. 1 and 5) or firmly in the same is clamped (see Fig. 4) and which in the area AR on one side of the Pressure P1 before and on its second side from pressure p2 after the flow resistance (1) is acted upon, so that the membrane in the area AR by the differential pressure ap12 is loaded and flexed elastically.

Together with the raised surfaces or cutting edges (4) (see Fig. 1, 4 and 5) on the diaphragm carrier (3) forms the diaphragm (2) (see Fig. 4 and 5) or a part (9) attached to the membrane (2) (see Fig. 1) one due to the changeable Membrane deflection variable flow resistance (5) which in the direction of flow seen after the flow resistance (1) is arranged and also from the to regulating amount of substance is flowed through. Through the flow resistance (5) from the pressure area P2 one or more outflow openings (6) are arranged separately in the membrane support (3), in which the output pressure p3 prevails, so that in addition to the differential pressure over the Flow resistance (1) (SPn2), which acts on the membrane surface area AR, in the Ag area the diaphragm is loaded by the differential pressure # p13 = P1 - P3 (see Fig. 1 and 2). The differential pressures # p12 act on surface S and # p13 on Ag in the same direction on the diaphragm (2) so that with increasing differential pressure # p12 and or or increasing differential pressure dp13, the deflection of the diaphragm (2) larger, the outflow cross-sections of the flow resistance (5) smaller and the flow resistance (5) gets bigger. With smaller Flow regulator for liquids and / or gaseous substances become differential pressures dp12 and / or dp13 conversely, the outflow cross-sections of the flow resistance (5) are larger, ie the flow resistance (5) is smaller.

By choosing the dimensions, shape and material accordingly the membrane (2), the dimensions and shape of the membrane support (3), in particular the Areas, tO, the membrane thickness of the membrane (2), the modulus of elasticity of the membrane material as well as the diaphragm spring travel up to the stop on the diaphragm carrier (3) is achieved, that when the differential pressure # p13 changes, the flow resistance changes (5) due to the effect of the differential pressure flp13 on the diaphragm deflection is so large that alternatively: - the differential pressure # p23 = P2 - P3 is around the same or almost the same amount as the differential pressure Dp13 changes, also because # p12 = # p13 - # p23 is, # p12 constant or almost constant and thus also the flow is constant or almost constant (see Fig. 6a) - the differential pressure dp23 at increasing differential pressure SP13 increases less than # p13, whereby # p12 increases and therefore the flow also increases with increasing differential pressure # p13 (see Fig. 6b) - correspondingly, the opposite applies to decreasing differential pressure # p13 Effect - the differential pressure # p23 increases with increasing differential pressure # p13 increases like # p13, whereby Sp12 is smaller and therefore the flow rate increases Differential pressure # p13 becomes smaller (see Fig. 6c) - correspondingly applies to falling Differential pressure # p13 has the opposite effect - the differential pressure Sp23 at increasing differential pressure SP13 increases significantly more than # p13, whereby # p12 drops sharply and so does the flow with increasing differential pressure # p13 drops sharply (see Fig. 6d) - correspondingly applies to falling differential pressure # p13 the opposite effect -.

The membrane (2) can be shaped differently (see Fig. 1, 4 and 7a and b) and lie loosely on the membrane carrier (3) or firmly clamped in the same be. Membrane shapes that are favorable for fixed restraint are shown in Figs. 4 and 7a and b. The cheapest membrane design is the flat circular disk.

A particularly simple, space-saving and inexpensive execution Flow regulator For liquid and / or gaseous substances there is an approximate form when the flow resistance (1), as shown in Fig. 4 and 5, as a breakthrough in the membrane (2) or in a body fastened in the membrane (2) is provided, the breakthrough in this body connects the two sides of the membrane (pressure area P1 and P2).

To protect the diaphragm (2) from impermissibly large deflections on the membrane support (3) along the bending line of the membrane (2) at marx. Deflection Support points or supports are provided (see Figure 5).

It is also possible to use a stop (7) (see Fig. 5) to reduce the Springback of the diaphragm (2) when the flow is switched off, i.e. differential pressure JP12 = 0, to a value at which the flow resistance (5) only a little smaller than the minimum required in operation, whichever is specified for the smallest Differential pressure # p23 is. This makes the starting jump very small. If this stop (7) is also, as shown in Fig. 5, on an additional elastic membrane (8) attached, which is acted upon on one side by the pressure Pl is that the stop (7) has moved away from the membrane (2) at pressure P1> O, so it is achieved with appropriate dimensioning that the flow resistance (5) is set to a value when the flow is switched off, i.e. P1 = 0, which is equal to or greater than the maximum flow resistance occurring during operation (5) is. This ensures that no start-up jump occurs or that the flow rate occurs increases from a lower value to the intended value when switched on.

Furthermore, the flow resistance (5) through a gap (see Fig. 4 and 5) for which the flow formula: Q = C x # p23 x h3 (C = constant, Q = flow h = height of the flow gap), i.e. a dependence of the flow Q depends on the third power of the gap height h, a linear dependence on the pressure difference jP23 and also a linear dependence on the material viscosity applies or through an aperture of any shape, e.g. through an annular aperture (see Fig. 1) for which the flow formula: Flow regulators for liquid and / or gaseous substances thus a linear dependence of the flow on the gap height h and a dependence on the square root of the differential pressure # p23, but no dependence on the material viscosity.

The advantages achieved with this invention are that - due to the hysteresis-free differential pressure regulator, low differential pressures Sp12 and so that larger cross-sections can be selected for the flow resistance (1), as with known flow regulators subject to hysteresis, which increases the risk of clogging the flow resistance (1) - is reduced - the regulator is practically wear-free is and gaseous and liquid substances are regulated without any lubricating effect can - at least slightly polluted substances can be regulated.

- in the version with stop (7) and diaphragm (8) no approach jump occurs and due to the low membrane mass of the membrane (2) and small control paths minimum settling times occur in the event of a sudden change in the differential pressure pi3 - depending on the definition of the dimensions and shape as well as the material of the membrane (1), the membrane carrier (3) with flow resistance (5) flow regulator are created can, which with increasing differential pressure flp13 a) constant or almost constant (Characteristic curve see Fig. 6a) b) rising (characteristic curve see Fig. 6b) c) falling or show a steeply decreasing flow rate (characteristic curve see Fig. 6c and d) accordingly the opposite effect applies to falling differential pressure flp13 - when used of these flow rate regulators, especially with increasing differential pressure flp13 falling or sharply falling flow to regulate the amount of substance for hydro- or aerostatic storage pockets, with the same stiffness and load capacity, a substantial reduction in pump pressures and amounts of substance, in the case of aerostatic Storage bags a significant reduction in air consumption - that is, a reduction the required energy and investment Flow rate controller for liquid and or gaseous substances tion expenditure is achieved, - such Flow regulators are inexpensive to manufacture - and can be built small.

A simplification of the calculation of such flow regulators results if not from the load on the diaphragm (2) shown in Fig. 2, but rather assumed the identical load on the diaphragm (2) shown in Fig. 3 will.

Claims (7)

Flow rate regulator for liquid and / or gaseous substances Claims: # Flow regulator for liquid and / or gaseous substances with a fixed or externally adjustable flow resistance (1) and a through the differential pressure flp1,2 prevailing at the flow resistance (1) Control device with a flow resistance through which the substance to be controlled flows (5) to control this differential pressure # p12, characterized by the following features: lol The control device for the differential pressure JP12 consists of a membrane carrier (3) with at least one drainage opening (6) and a 1.2 on the membrane support (3) overlying or attached to the membrane carrier, in the area AR of the differential pressure # p12 and elastic membrane loaded by differential pressure # p13 in the area Ao, where 1e3 is seen in the direction of flow after the flow resistance (1) and in front of the drainage opening or openings (6) between the membrane (2) and the membrane support (3) the variable due to the variable differential pressures Sp12 and # p13 Diaphragm deflection variable flow resistance (5) is located. 2. The flow resistance (5) is at least near the location of the greatest Deflection of the membrane (2) and is determined by the membrane support (3) or attached to the diaphragm (2) or through to the diaphragm (2) and to the diaphragm support (3) Parts with raised surfaces or cutting edges surrounding the drainage opening (6) (4 and 9) formed. 3. The dimensions and shapes of the flow regulator and the Flow regulator parts, in particular the size of the effective area A0 of the differential pressure # p13, the spring constant of the diaphragm deflection of the diaphragm (2) under load by the differential pressure # p13, the size of the flow resistance (5) as a function of the deflection of the membrane (2) and the size of the flow resistance (1) are determined so that by the load on the membrane (2) due to the load the area Ao with the differential pressure Sp13 changes the flow resistance (5) becomes that the differential pressure # p12 and thus the flow Q with a variable differential pressure jP13 - constant or almost constant (see Fig. 6 curve a) or Flow regulator for liquid and / or gaseous substances - with increasing differential pressure SP13 becomes smaller and increases with decreasing differential pressure # p13 (see Fig. 6 Curve c) or - with increasing differential pressure # p13 much smaller and with smaller increasing differential pressure # p13 much larger (see Fig. 6 curve d) or - with larger increasing differential pressure # p13 and decreasing differential pressure # p13 becomes smaller (see Fig. 6 curve b). 4. In the diaphragm (2) there is a flow resistance (1) forming breakthrough which connects the pressure spaces pi and P2 to one another or it is a part in the membrane with a flow resistance (1) forming Breakthrough, which connects the pressure spaces pi and p2 with each other, attached. 5. The membrane support (3) has impermissible membrane deflections preventive support points or surfaces for the membrane (2) (see Fig. 5). 6.1 mm diaphragm carrier (3) is a spring back of the diaphragm (2) limiting stop (7) attached (see Fig. 5). 6.2 The stop (7) limiting the diaphragm resilience is on a fastened on one side by the pressure p1 loaded membrane (8). 7.1 The membrane is a flat or curved plate (see Fig. 1 and 5) or 7.2 the diaphragm is radially corrugated (see Figure 4) or 7.3 the diaphragm is axially corrugated (see Fig. 7 a) or 7.4 the membrane is diagonally corrugated (see Fig, 7 b). 8, The flow regulator is used to regulate the amount of substance for used to supply hydro- and aerostatic bearings.