DE2529207A1 - FLOW CONTROL VALVE - Google Patents

Description

R. 272S

5.6.1975 My / Ht

Attachment to

Patent and

Usage benefit registration

ROBERT BOSCH GMBH, 7 Stuttgart t

Flow valve

The invention relates to a flow dividing valve with an inlet and two outlets and each with a measuring throttle point in each partial flow and with a pressure compensator assigned to both partial flows .

609884/0445

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In a known flow divider valve of this type, measuring throttles are provided with a constant cross section. With these measuring throttles the flow changes proportionally to the square root of the pressure gradient. This quadratic dependency leads to small flows the accuracy of the flow divider valve is poor, while with large flows the pressure losses become large. Above all the ratio of the partial currents to one another is not variable with constant measuring throttles.

The object of the invention is to create a flow divider valve that works precisely with small currents and contributes to their losses large currents are as small as possible.

This is achieved according to the invention in that each measuring throttle point has a throttle member loaded by a biasing force, the flow cross-section of which is greater than that on the throttle member occurring pressure gradient changes according to an exponential function.

In this way, a flow dividing valve is achieved which has a high degree of accuracy over a large range of the flow path and whose losses are relatively low at large currents.

A particularly advantageous embodiment is achieved when the biasing force is adjustable at at least one of the measuring throttle points. This gives a current divider, its divider ratio is variable over a large setting range.

Further particularly advantageous embodiments of the invention result from the remaining subclaims, the description and the drawing.

The drawing gives an embodiment of the subject matter of the invention again, the single figure of which shows a flow divider valve in a simplified representation.

609884/0445

^R -

27 2 he "

In the figure, the flow dividing valve is denoted by 10, the housing 11 of which has an inlet 12 and a first (13) and second outlet 14. A first measuring throttle point 15 is connected in the first partial flow between input 12 and first output 13, and a second, identical measuring throttle point 16 is connected in the second partial flow. ^{A pressure compensator l v} known per se is also assigned to both partial flows. Since both measuring throttle points 15 » 16 are designed to be identical to one another, only the measuring throttle point 15 will be discussed below.

The measuring throttle point 15 has a throttle member 19 which is loaded by a spring 18 and which has a flow cross section 20. the The preload of the spring 18 can be adjusted with a screw 21. The flow cross section 20 is now designed so that its the respective effective value changes over the iiub of the throttle element 19 and thus over the pressure gradient according to an exponential function. The effective cross-section A in each case results from the equation

A = C * e ^s

where C is a constant and s is the respective stroke. Included the respective stroke can be derived from the equation

^s = ^c p 'P ⁺ Λ ^s

determine where Cp is the spring constant and ρ is the pressure drop. It can be set individually for each measuring throttle point 15, 16 by pretensioning the spring 18. This means that you can also write

A = C * e ^(C F 'P ⁺ A ^S)

In general, the flow rate at a throttle point results from the equation

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Q = k * ψ "" ¹

where k is a constant and ρ is the pressure gradient. This orifice equation can also be written in conjunction with the equation for the flow area

Q = k * } $? ' C * e ^(C F * P ⁺ 4'b)

This therefore applies to the ratio of the first partial flow Q ₁ to the second partial flow Q ₂

Q ₁ k ^ / p7 C e- ^(C F 'Pl ⁺ A ^s l> Q ₂ k * ψ ^' C * e ^(C F ' ^p 2 ⁺ As ₂ ) Since the pressure gradient P _{1 is} equal to p " is, also applies

h = _e ⁽ A ^s i - Δ ^S 2 ⁾

The ratio of the first to the second partial flow can therefore be varied within wide limits simply by varying the spring preloads change. The ratio is independent of the respective flow rate and the pressure load on the partial flows. The flow valve works with high accuracy even with small currents.

It is of course possible to make changes to the design shown. As an alternative or in addition to the spring

18 a control line 22 can be provided, via a not The pressure supply shown can - as well as by changing the spring preload - the divider ratio can be varied. A particularly advantageous remote adjustment is possible via an electrohydraulic proportional adjustment. For the Adjustability of the dividing ratio is sufficient if the preload force is already adjustable at a measuring throttle point; is however, if they are adjustable at both measuring throttle points, the setting range is advantageously larger accordingly.

Claims (5)

- 5 - · R. 27 2 y Expectations f 1.j flow divider valve with one input and two outputs and with one measuring throttle point in each partial flow and with a pressure compensator assigned to both partial flows, characterized in that, that each measuring throttle point (15j 16) has a throttle member (19) loaded by a biasing force, its Flow cross-section (20) is above that occurring on the throttle element Pressure gradient changes according to an exponential function. 2. Flow divider valve according to claim 1, characterized in that the biasing force at at least one of the measuring throttle points (15, 16) is adjustable. 3. flow divider valve according to claim 1 or 2, characterized in that that the throttle members (19) have the same flow cross-sections (20) and that the pretensioning forces of springs (18) are the same Spring constant can be applied. ^. Flow dividing valve according to claim 3 »characterized in that the space on the throttle member (19) receiving the spring (18) is connected to a control line (22). 5. Flow dividing valve according to one of claims 1 - H, characterized in that the measuring throttle points (15, 16) and the pressure compensator (17) are arranged in a common housing (11). 6Q988A / 0U5 e e r s e i f e