DE3321754C1 - Flow meter - Google Patents

Description

a) a storage space known per se (9; 109; 209) with variable volume, which is delimited by a movable wall (11, 111; 211) , the side of the movable wall facing away from the storage space having a pressure space (29; 129; 229) , which is connected to the side of the flow meter (4) facing away from the storage space, and is additionally loaded with a force exerted by a component (spring 28, 128), and

b) a shut-off valve (10, 110; 210) connected downstream of the storage space and in series with the flow meter, which opens when the movable wall reaches a first position (B) during the outward movement, which corresponds to a larger storage volume, and closes when the movable wall reaches a second position (A), which corresponds to a smaller storage volume, during the inward movement.

2. Flow meter according to claim 1, characterized in that a throttle element (22; 122; 222) connected downstream of the storage space (9; 109; 209) is also in series with the flow meter (4) and the shut-off valve (10; 110; 210) and can be changed from a value of greater throttle resistance to a value of smaller throttle resistance when the movable wall (11; 111; 211) is displaced beyond the first position.

3. Flow meter according to claim 1 · or 2, characterized in that the shut-off valve (10) has a has a constant closing movement causing drive.

4. Flow meter according to claim 2 or 3, characterized in that the throttle element (22; 122) is located between the storage element (9; 109) and the shut-off valve (4).

5. Flow meter according to one of claims 1 to 4, characterized in that the movable wall (11; 111; 211) has a rolling membrane (13; 113) .

6. Flow meter according to one of claims 1 to 5, characterized in that the shut-off valve (10) is a solenoid valve and that an activator (15) is connected to the movable wall (11), the stationary sensor (16, 17), which the first and second position (B, ^ are assigned, excited.

7. Flow meter according to claim 6, characterized in that the sensors (16, 17) are without contact are controllable.

8. Flow meter according to one of claims 1 to 5, characterized in that the closure piece (131) of the check valve (110) is adjustable by an adjusting element (135) which can be held in a closed and an open position by means of a locking device (140) and which is connected to the movable wall (111) via a backlash coupling (13), by means of which the adjusting element is moved from the closing to the opening at the end of the backlash

nungsposition and is traceable back.

9. Flow meter according to claim 8, characterized in that to form the locking device (140) on the adjusting element (135) recesses (143,144) are provided, in which the resiliently mounted locking body (142) engage.

10. Flow meter according to claim 8 or 9, characterized in that the lost motion coupling (134) has two drivers (136, 137) connected to the movable wall (111) which, with the interposition of a spring (138), act on two abutment surfaces (139) acting in opposite directions 139a,} act on the adjusting element (135).

11. Flow meter according to one of claims 2 to 10, characterized in that the adjustable throttle element (23; 123) of the throttle member (22; 122) has a predetermined rest position corresponding to the value of the greater throttle resistance, and with the movable wall (11; 111 ) is connected via a driver (27; 127) , by which the throttle element can be driven into a working position corresponding to the value of the lower throttle resistance when the movable wall is beyond the first position (B) .

12. Flow meter according to one of claims 8 to 11, characterized in that the driver (127) is formed on the actuator (135).

13. Flow meter according to claim 11 or 12, characterized in that the throttle element (22, 122) is a filler body which partially fills an outlet opening (24; 124) of the storage space (9; 109) in the rest position and in the working position from the Exit opening is moved out.

14. Flow meter according to claim 8 and 13, characterized in that the valve seat (132) of the shut-off valve (110) is provided at the outlet opening (124) of the storage space (109) and that the closure piece (131) as a valve plate and the throttle element (123 ) are designed as an associated filler body.

The invention relates to a flow meter with a flow meter, such as an impeller meter, and an additional device increasing the measuring accuracy in the lower measuring range.

It is known that flow meters, such as impeller meters with non-contact scanning, over the largest Part of the measuring range provides very precise results, but with small flow rates per unit of time Measurement errors have to be accepted. At very low flow velocities speaks the diameter is no longer on at all. This can lead to difficulties if due to the Flow measurement a consumption bill is to be created, for example when in district heating systems the heating water consumption or the dependent amount of heat must be determined.

Numerous additional devices have therefore already become known to reduce the measurement accuracy in the lower To increase the measuring range. Thus, by generating vibrations, the bearing friction of a rotor of the Reduce the flow meter (DE-OS 3124 683). You can through configurations of the measuring chamber Press down the elevation of the error curve (DE-PS 46 624). You can push an impeller through a nozzle

Let the jet act and give it a high speed (DE-OS 26 16 323). In all cases it can be but only reduce the measurement error in the lower measurement range, but not eliminate the fact that with very small flow velocities of the runner of the flow meter no longer responds

There is also a flow meter known (DE-OS 26 21 278), measured with the pulsating flow rates should be, as they are delivered, for example, by a fuel diaphragm pump in a motor vehicle will. The inlet of the flow meter is with a storage space with variable volume connected, which is bounded by a movable wall in the form of a spring-loaded membrane. the Opposite membrane surface delimits a pressure chamber, which is connected to the outlet of the flow meter is in connection with the storage space, the pulsations can be smoothed, so that the flow meter determines the mean flow rate

The invention is based on the object of specifying a flow meter of the type described above, in which not only the errors in the lower measuring range are reduced, but also very small ones Flow rates are detectable.

This object is achieved according to the invention in that the additional device has:

a) a storage space known per se with variable volume, which is replaced by a movable

'Wall is limited, the side of the movable wall facing away from the storage space Limited pressure space with the side of the flow meter facing away from the storage space is connected, and is additionally loaded with a force exerted by a component (spring 28, 128) is and

b) a shut-off valve downstream of the storage space and in series with the flow meter, that opens when the movable wall moves outward to a first position, which one corresponds to larger storage volume, reaches and closes when the movable wall at the Inward movement reaches a second position, which corresponds to a smaller storage volume

If very small flow rates occur in this embodiment, the shut-off valve is closed. The liquid therefore collects in the storage space until the movable wall then reaches the first position the shut-off valve is opened and the contents of the storage space are passed through the flow meter at once when the movable wall reaches the second position, the shut-off valve closes again. In this mode of operation the flow measurement is problem-free because the liquid flows through at a sufficiently high speed flows through the measuring chamber of the flow meter. The shut-off valve can be in front of or behind the flow meter be arranged.

The force loading the movable wall can be a spring, elastic material, weights, a Floats and the like are generated. She allows the storage space contents after opening the shut-off valve at a predetermined speed via the To send flowmeter.

In a preferred embodiment, it is ensured that a downstream of the memory space Throttle body is also in series with the flow meter and the check valve and of one value larger throttle resistance can be changed when the movable wall is displaced beyond the first position will. The throttle element causes the storage space contents to be released after the shut-off valve has been opened extends over a certain time, so that the start-up and run-down conditions in the flow meter are negligible. However, as soon as a larger flow rate is to be measured, the throttle element becomes automatically disabled so that the normal

ίο measurement is not hindered.

It is favorable if the shut-off valve has a constant closing movement. Since the closing movement is a Problems can be avoided when there is a sudden closing movement because of the After-running of the flow meter occur. Such a closing movement can, for example, by means of a Damping device can be achieved. The shut-off valve can also be used as a cover, namely like a camera, be trained, which closes slowly.

The throttle element is expediently located between the storage space and the shut-off valve. In this way the throttle element can be controlled from the movable wall without the need for seals are.

The side of the movable wall facing away from the storage space delimits one particularly advantageously Pressure chamber which is connected to the side of the flow meter facing away from the storage chamber. To this Way, the specified force only needs to counter the pressure drop at the flow meter after opening the shut-off valve to act so that correspondingly small forces are sufficient.

In particular, the movable wall has a rolling membrane. This allows a relatively large Stroke, so that a correspondingly large change in volume of the storage space and relatively large Distances between the first and second positions of the movable wall are possible. As a movable wall But there are also pistons that are tightly guided in a cylinder, metal bellows, clamped diaphragms and the like

The shut-off valve can in particular be a solenoid valve. In this case it should be one with the movable wall Be connected to the activator, the stationary sensors, which are assigned to the first and second position, excited For example, the activator is a magnet and the stationary sensors are formed by reed switches. A purely mechanical design consists in that the closing piece of the shut-off valve is secured by an adjusting element This can be adjusted by means of a locking device in a closed and an open position and which is connected to the movable wall via a lost motion coupling, by means of which the actuating element at the end of the backlash from the closing

The combination of the locking device and the lost motion clutch can be moved into the open position and back allows the shut-off valve to be opened during the movement of the movable wall from the first in the second position is open and closed during the movement from the second to the first position keep.

To form the locking device, recesses can be provided on the actuating element, into which are resilient engage the stored locking body. Only when the control element is moved with sufficient force is, the locking bodies are pressed against the force of the associated springs from the recesses Here, the lost motion clutch can be used with two

5 6

have movable wall connected drivers that can be driven.

with the interposition of a spring on two in opposite positions. The letters A, B and Care three positions

Opposite directions acting abutment surfaces of the movable wall 11 illustrates. In the place

act on the actuator. Such a backlash clutch treatment A , the sensor 16 is energized, in the position B is

works quietly and safely. 5 the sensor 17 is energized and in position C the engages

In a preferred embodiment, there is a driver 27 on the head 25a.

ensures that the adjustable throttle element of the throttle- The movable wall 11 is loaded by a spring 28

organs a given throttle constant greater than the value. On the opposite of the storage space 9

Resistance has corresponding rest position, and with side there is a pressure chamber 29, which has a

the movable wall is connected to the outlet connector 3 via a driver

is the one that moves the throttle element into a value smaller than this. This flow meter works as follows:

Ren throttle resistance corresponding working position, the shut-off valve 10 is closed. If now

when the movable wall moves beyond the a very small amount of liquid over the inlet

first position is here, all connecting pieces 2 can flow, the shut-off valve 10 remains closed,

elements must be arranged in the storage space, so 15 The storage space 9 increases, however, because the

that no sealing is required. movable wall 11 upwards against the force of the spring

The driver can be shifted directly on the movable 28. As soon as it reaches position B and

Wall or be formed on the actuator. the sensor 17 responds, opens the shut-off valve and the

With particular advantage, the throttle element is a stored amount of liquid is under the influence

Filler body, which in the rest position has an exit opening 20 of the spring 28 from the storage space 9 via the

tion of the storage space partially fills and pressed in the ar-flow meter 9 to the outlet connection 3. Here

moving position out of the exit opening causes the throttle member 22 such a throttling,

is. This results in a low pressure drop with a large that the flow velocity is sufficient to achieve the

Flow. Make flow meter 4 work satisfactorily,

In a further embodiment, the valve seat of the 25 can on the other hand make the measurement time so long that

Stop valve at the outlet opening of the storage tank start-up and run-out conditions on the measurement result

be provided in space and the closure piece as a valve have no significant influence. When the moveable

tilteller and the throttle member as an associated re wall 11 has again reached the position A and the

Be formed filler body. Throttle body and blocking sensor 16 responds, the blocking valve 10 is so slow

valve therefore form a structural unit. 30 closed that the outlet movement of the impeller

The invention is not impaired below with reference to the flow meter 4 in the drawing. This cycle

preferred exemplary embodiments shown, klus can be repeated several times,

explained in more detail. If, on the other hand, there is a larger inflow,

Fig. 1 is a schematic representation of a first, the movable wall 11 over the position B to in

Embodiment, 35 raised the position C and beyond. Since here-

F i g. 2 is a schematic representation of a second in which driver 27 is effective, the throttle embodiment and element 23 lifted out of the outlet opening 24,

F i g. 3 a schematic representation of a detailed so that the throttling effect is omitted. With such a

th embodiment. The flow meter 4 operates normally and

The in Fi g. 1 shown flowmeter 1 has 40 without significant errors.

an inflow connection 2 and an outflow connection 3. The liquid to be stored depends on the

In between there is an impeller designed as a respective relationship and depending on the type of passage

The flow meter 4, the flow meter in a measuring chamber 5. With a vane knife it is enough, for example

ordet and by contactless scanning using 4% of the maximum flow rate per unit of time

an optical sensor 6 pulses to a counter 7 45 to be able to store. In one embodiment

whose counter reading at this point in time was therefore the change in volume of the storage space

corresponds to the flow rate. 9 a total of 0.2 liters, while the flow meter in the

The flow meter 4 is a Zusatzvorrich- measuring range of 40 to 1000 liters / h normal, that is, device 8 upstream, which worked a storage space 9 and a continuous flow,
downstream electromagnetic shut-off valve 10 50. In the embodiment according to FIG. Rolling diaphragms 13 are formed for corresponding parts. With the plate is about a 100 compared to F i g. 1, increased reference numerals indicate that an activator 15, for example a permanent magnet, is used. A closure piece 131 of the check valve 110 arbunden, the two superposed sensors 16 55 cooperates with a valve seat 132, which the Aus and 17, z. B. reed switch, can excite. These are connected to the passage opening 124. This closure piece is connected via lines 18 and 19 to a switching device 20 in part with the throttle element 123, which is arranged in the connection, which in turn is an electromagnet 21 output opening 124.
of the electromagnetic shut-off valve 10 can excite. In the case of the movable wall 111, the plate 12 is provided with a hydraulic 60 known per se, a molded part 112 with a receiving ring space for the damping device 21a, which replaces the spring 128. The molded part 112 carries a rod slowing closing movement. 133, which via a lost motion clutch 134 with an adjusting

A throttle element 22 has a throttle element 23 connected to an element 13. The lost motion clutch has

NEN in the outlet opening 24 of the storage space 9, two pins 136 and 137 designed as drivers

arranged packing. This is with a rod 65 of the rod 133, which is each on one end of a spring 138

ge 25 provided, which is guided in a bearing 26 and can act on, and opposing Wi-

upper end carries a head 25a which is connected to one of the bearing surfaces 139 and 139a. on the actuator 135, the

the movable wall 11 connected driver 27 with the other end of the spring 138 together.

can work. A locking device 140 has two roller-like locking bodies 141, the axis of which are each loaded by a compression spring 142 and there optionally in a recess 143 or one below it Can grip recess 144 on Stellelemenl35.

With this flow meter, the following mode of operation results: In the idle state, the shut-off valve 110 is closed. When there is a small inflow, the shut-off valve remains closed. However, the movable wall 111 is moved upward. Here, the adjusting element 135 is held in the closed position by the locking device 140. Only when the driver 137 reaches the spring 138 in position B is the actuating element 135 taken upwards, the locking bodies 141 passing from the recess 143 into the recess 144. Here, the head 125a of the rod 125 is slightly raised by the driver 127 on the adjusting element 135, so that the shut-off valve 110 is opened, but the throttle element 122 still maintains the state of high throttle resistance Output. As soon as the position A is reached again, in which the driver 136 acts on the spring 138 from above, the adjusting element 135 moves downwards and the shut-off valve 110 is closed again. This cycle can be repeated several times.

If there is a larger inflow, the movable wall 111 is displaced further upwards via position B , the rod 125 and thus the throttle member 123 being pulled upwards until it is finally lifted completely out of the outlet opening 124 in position C. Now the inflow can reach the flow meter without throttling.

In Fig. 3, in which reference numbers increased by 200 are used for corresponding parts, is the memory space 209 is connected to the inflow connection 202 via a branch line 230, while the outflow connection 203 goes off from the pressure chamber 229. The check valve 110 and the throttle valve 122 are, as in Figure 2, with The between the stopper of the shut-off valve 110 and the movable wall 211 are combined with each other arranged parts, such as lost motion clutch and the like. Are in a similar manner to FIG. 2 trained the movable The wall can also be formed by a sealed piston or by a metal bellows.

The flow meter is particularly suitable for district heating systems in which the water consumption or the heat energy consumption is to be determined over longer periods of time

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Claims (1)

Patent claims: 1. Flow meter with a flow meter, such as an impeller meter, and an additional device increasing the measurement accuracy in the lower measuring range, characterized in that the additional device (8, 108) has: '