DE8702221U1 - Pump with valves controlled by the pumped medium - Google Patents

Description

PATENT ATTORNEYS · ···· ."..··. ·'"·'. 12. Ffib

'I . &iacgr;!; .. . 78 FREIBURG 1. BH. ' ^eWl

f DIPL.-ING. H.SCHMITT j , ; · ; ; ,· · ; ; ; sreikOniostb. ia S/mat

&Lgr; DIPL.ING. W. MAUCHER TELEPHONE: (07 eil 70773

Note: Mr. Erich Becker Glöcklehofweg 13

7812 Bad Krozingen

Pump with valves controlled by the pumped medium

The innovation relates to a pump according to the preamble of claim 1.

A diaphragm pump for generating vacuum is already known with valves controlled by the pressure differences of the pumped medium, both of which are designed as check valves

(DE-AS 11 84 447). Such diaphragm pumps have proven to be good in terms of pumping performance. However, to drive such pumps, a relatively expensive motor with a significantly higher motor output than the actually required drive power , 25 is required in order to ensure that the diaphragm pump starts reliably from any starting position. This is due, among other things, to the following starting situation: If the pump piston or the diaphragm with the associated connecting rod comes to a stop shortly before the top dead center, for example in a diaphragm pump of the type mentioned above that is used to generate compressed air, a pressure is maintained in the compression chamber that is only slightly below the discharge pressure. The two valves controlled by the pressure differences of their gaseous conveying medium (pump inlet and pump outlet valve) remain in this working position.

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point of the pump is closed. If the pump is to start from this position, the maximum torque must be generated by the motor alone during the start-up moment. In a diaphragm pump driven by connecting rods, the required torque in the previously described, unfavourable position of the crank angle can be, for example, 75 \ higher than the average torque required to operate the pump. Accordingly, the electric motor must be designed to be powerful and is

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on the other hand, it results in a correspondingly lower average torque because the pump's power requirement changes significantly over one crank angle revolution and the inertia of the rotating drive parts balances out the peak loads of the pump's drive requirement. However, when starting from an unfavorable crank angle position, these inertia reserves are not available.

For this reason, various solutions have already been found for crankshaft-driven pumps, namely diaphragm pumps, but these are still disadvantageous.

One possible remedy is to equip the pump with a motor that is larger than the required continuous output, so that it can start the pump against the desired discharge pressure even from an unfavorable crank angle position. This solution is, as mentioned, complex.

Furthermore, additional valves, such as an electromagnetically controlled additional vent valve, have already been used to ensure safe starting with a relatively small engine. With the help of such additional, relatively expensive additional valves, the pre-compressed air in the pump delivery chamber can be

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Remove the pumped medium from the pump chamber and thus improve the starting conditions of the pump. However, this not only makes the entire pump unit more expensive, but also more complicated in construction and therefore more susceptible to failure. 5

To avoid the aforementioned disadvantages, a pump with valves controlled by the pressure differences of the gaseous medium has already been created, of which the valve on the system connection side is a check valve.

in valve and at the ^valve remote from the pump a bypass is provided which remains temporarily open outside the closing times when the pump starts up and is closed at least in the operating speed range of the pump during the closing times of the valve remote from the system (DE-OS 30 05 834). Such pumps have proven themselves in a number of applications, but they also have a number of disadvantages, especially in certain areas of application. For example, the valve remote from the system usually has a valve tongue and the The sealing surface assigned to this is set back in the closing direction compared to the undeflected position of this valve tongue. The extent of this set back, the operating speed range of the pump and the natural frequency of the valve tongue should be well coordinated with one another in these previously known pumps. This requires a certain amount of work; furthermore, such pumps are not equally suitable for different purposes. In different areas of application, adjustments may have to be made. Vacuum pumps may require a slightly different design than pressure pumps of the type described above.

The particular task is therefore to develop a pump

3E> according to the preamble of claim 1,

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where an easier start-up with hardly any weight
can be achieved with a minimum of additional effort, without
the pressure conditions in the pump in connection
standing upper or lower pressure vessel system during still-

the pump and the start-up-facilitating
measures noticeably changes. The pump should be
Use as a vacuum or pressure pump largely
be of the same design.

The solution to this problem according to the invention consists in particular in the fact that in a pump according to the preamble of claim 1, a bypass-like leakage point is provided at the pump inlet and at the pump outlet valve, even in the valve closed position, and a bypass-like leakage point is provided at the connection

line for the pressure vessel system a pressure holding valve

This provides the following advantages: The pressure vessel system connected to the pump connection line, e.g. a vacuum vessel, remains closed when the pump is stopped, while

probably the pump inlet and pump outlet valve (

are slightly leaky and during pump operation ·

pressure built up in the pump room or the U

Vacuum during standstill of the pump, if necessary also during

low speed can escape. This then occurs when the ^;

The torque required by the pump is correspondingly small.
Leaving aside any dimensioning issues regarding the bypass-like leaks,
these leaks can be practically eliminated at the pump inlet and the pump outlet in the same, very

be created easily or the pump itself is
without significant changes for the production of
Suitable for both pressure and vacuum.

The features of the second claim result in
not only easy to manufacture and replace; _;

on the intermediate and end cover regarding the '

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Valve sealing surfaces, but the bypass-like leakage points can be easily attached to the valve sealing surfaces and the valve tongue(s) arrive in an undeflected position without any special deformation in the closed position, although a desired, slight leakage is achieved in both valves.

According to an advantageous development of the innovation, the pressure holding valve for the pressure vessel system is located near the assigned pump inlet valve or pump outlet valve, preferably on the pump itself or on its connecting pipe connection. The closer the pressure holding valve is to the pump valves or the pump chamber, the smaller the amount of pumped medium, which escapes when the pump is stopped; accordingly, when the pump starts up, the amount of fluid that must be brought back to the desired pressure or negative pressure in the pump or its immediate surroundings is also small.

Although the invention proposal can also be implemented with a piston pump, the combination according to the invention is particularly advantageous in conjunction with a diaphragm pump, because it enables an oil-free or similar foreign substance-free operation both with regard to the pump with the aid of the diaphragm and with regard to the pump valves ζ 25 with bypass-like leakage points. Under otherwise identical conditions, e.g. with correspondingly small electric drive motors, externally controlled valves that require lubrication can be avoided. In Fort In this design, the membrane is driven in a known manner using a connecting rod. This not only facilitates a simple construction of the pump, but also, among other things, an easy replacement of the membrane, which is a wearing part. In addition, As is known, such connecting rod-driven diaphragm

pumps should be designed so that their dead space remains as small as desired.

A particularly simple, reliable manufacture and reliable operation of the bypass-like leakage points on the pump valves is achieved by the fact that this leakage point(s) is formed by a recess in the valve sealing surface, which protrudes slightly radially over the valve tongue at least at one point, whereby the recess is preferably formed by a notch. This can, for example, easily be attached to the valve sealing point using a chisel of a selectable length with the help of an appropriately dimensioned length. Tests have shown that such a small cross-section

!5 The leak point is, on the one hand, sufficient to allow the pressure built up during operation or the corresponding vacuum to be released when the pump is at a standstill or running slowly , and, on the other hand, the bypass-like leak point thus formed does not lead to a significant deterioration in the pump's performance at operating speed. This is particularly true for pumps with a small flow rate or a low differential pressure between the pump inlet and pump outlet.

Additional training courses are listed in further sub-claims.

A particularly advantageous embodiment of the invention is explained in more detail below in conjunction with the drawing. They show, in different scales, and somewhat schematically

Fig. 1 is a partially sectioned side view of a diaphragm pump and part of its electric drive motor,

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Fig. 2 the upper part of a pump similar to Fig. 1, which is used to generate a vacuum and is connected to a vacuum container,

Fig. 3 the upper part of one of the pumps according to Fig. 2

similar pump that is used to generate pressure and is connected to a pressure vessel,

Fig. 4 a partial view of an intermediate cover and a valve plate in the area of a valve tongue with the end cover omitted

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Fig. 5 a partial section through the valve plate and the intermediate cover according to the section line V-V in Fig. 4

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A diaphragm pump 1 (Fig. 1) has a housing 2, an intermediate cover 3 and a cover 4. The pump diaphragm 5 is clamped between the housing 2 and the intermediate cover 3 and is driven by the drive shaft 8 of an electric motor 9 by means of a piston 6 via an eccentric part 7. The cover 4 contains the suction connection 10 and the pressure connection 11. In the area between the intermediate cover 3 and the cover 4, which is shown more schematically in Fig. 1, a valve plate 12 is clamped in. It has a valve tongue 21 in the area of its inlet valve 13 (Fig. 1 and 2) and another valve tongue 22 in the area of the outlet valve, which can also be clearly seen in Fig. 2, 3 and in particular Fig. 4. These inlet and outlet valves 13 and 14

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of the pump are controlled in a known manner by the pressure differences | of the gaseous pumping medium of the pump | and are designed as check valves. The |

The embodiment according to Fig. 1 and 2 of the pump 1 is designed as a vacuum pump. Its suction connection 10 is connected to a vacuum container 16 via a highly schematically shown connecting line 15a. Instead, it can also be connected to another vacuum vessel system, e.g. to the vacuum part of a piston evaporator.

According to the invention, a bypass-like leakage point 17 is provided on the pump inlet valve 13 and on the pump outlet valve 14, even in the valve closed position (Fig. 1 to 5). Furthermore, the connecting cable 15 a for the A pressure holding valve 18a is arranged in the vacuum container 16 or similar pressure vessel system. In the embodiment, this is designed as a check valve. If the vacuum pump according to Fig. 2 is in operation, it acts via its suction _; connection 10 and the connecting line 15 a vacuum generating on the contents of the vacuum container 16, whereby accordingly the suction strokes of the pump, the pressure holding valve 18 a in the connecting line 15 a opens and closes. If the pump 1 is at a standstill as shown in Fig. 1 and 2, the pressure in the pump chamber 28 and in the

&Lgr; 25 from there to the pressure holding valve 18 a, The vacuum built up during pumping operation is released via the two leak points 17 of the pump valves 13 and 14. The vacuum container 16 or the like is kept closed by the pressure holding valve 18a. In a vacuum pump 1 working against atmospheric pressure, for example, a vacuum builds up in the area between the outlet valve 14, the pump chamber 28 and the inlet valve 13, reaching to the

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Pressure holding valve 18 a ₍ also uniformly at atmospheric pressure. The pressure conditions in the vacuum vessel 16
are therefore not influenced by the intended bypass-like leak points 17 at the pump valves 13 and 14 when the pump is stopped.

If the stationary pump i starts to run in this initial situation, only a comparatively low starting torque can be generated by the electric motor 9 due to the pressure conditions described above and the leak points 17 at the pump valves 13 and 14.

The same applies to the slightly modified version of the same
Principle using diaphragm pump 1 a according to Fig. 3, which is intended for pressure generation and whose connecting line 15 b via a pressure holding valve 18 b to a

Pressure vessel 27 b. Instead of this, another pressure vessel system can be connected to the pressure connection 11 of the pump 1 a. If this runs according to
Fig. 3 as a pressure pump, it delivers in the usual way

e.g. sucked air into the pressure vessel 27, whereby the pressure holding valve 18 b for the pressure vessel 27 opens or closes with corresponding pressure strokes of the diaphragm pump 1 a.
with a corresponding pressure drop during the suction stroke
closes. When the pressure pump 1 a is at a standstill,

the pressure of the pumped medium built up in the pump chamber 28

because of the bypass-like leakage points 17 intended for the pump valves 13 and 14, and escape, for example, against the direction of delivery (see arrows 29) from the area of the pump 1<l and, if applicable, the adjacent section of the connecting line 15 b and, for example, reduce to atmospheric pressure when the pressure pump 1 a sucks in atmospheric pressure. To start the
Pump 1 a is then also, for the reasons already explained in connection with pump i in Fig. 1 and 2,

only a comparatively low starting torque from

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Electric motor 9. The end cover 4 and the intermediate cover 3 each have a substantially flat clamping surface 36 and 35 facing the valve plate 12. In the area of the inlet valve 13, below its valve tongue 21, there is a valve tongue recess 33, which creates space for the valve tongue movement. From this recess 33 for the valve tongue movement and thus from the (open) inlet valve 13, a supply line 31 for the pumped medium leads to the pump chamber 28. The area of the clamping surface 36, on which the valve tongue 21 of the inlet valve

13 and seals, represents the valve sealing surface 19 E of the inlet valve. In the outlet valve 14, the recess 33 for accommodating the valve tongue movement of the associated valve tongue 22 is located in the cover plate 4.

¹ B. The corresponding valve sealing surface 19 A (Fig. 2 and 4) is formed by a corresponding area of the clamping surface 35 of the intermediate cover 3. This valve surface 19 A has, in plan view, analogous to the valve sealing surface 19 E approximately circular ring shape (see Fig. 4) and is covered there by the approximately circular part of the valve tongue 22 of the outlet valve 14 in the closed position. From the pump chamber 28 a discharge line 32 designed as a bore leads into the area of the outlet valve 14, which is covered there in the closed position in the manner already explained in connection with the inlet valve 13. From Fig. 4 it is particularly clear how the pump outlet valve

14 the bypass-like leakage point 17 provided in the form of a notch 25 on the valve surface 19 A there radially laterally the corresponding part of the The cross-sectional profile of this notch-like leakage point 17 is clearly visible in Fig. 5. In Fig. 1, in a more schematic representation, it is clear from the dot-dash line 38 how the conveying medium is safely can escape from pump 1 via the creepage path.

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The same applies to the bypass-like leakage point at the inlet valve 13. In conjunction with the pressure-maintaining valve 18, it is comparatively easy to ensure that when the pump 1 or 1a is at a standstill or at a low speed, the vacuum or pressure built up in it can be reduced, thereby keeping the required starting torque low. These bypass-like leakage points 17, particularly when they are formed by notches 25 that project radially slightly beyond the valve sealing surfaces 19, can operate without being susceptible to failure despite their smaller cross-section (see Fig. 5). The small cross-section and also the necessary deflection around the valve tongue ⁽ cf. valve tongue 22 in Fig. 4 and dash-dotted line 38 in Fig. 1) ensure that during continuous operation of the pump 1 or 1a the leaks 17 do not result in any significant deterioration in the operation of the pump.

The design of the pressure holding valves 18 a and 18 b as check valves represents a particularly simple design. In Figures 2 and 3, these pressure holding valves 18 are schematically located approximately in the middle of the connecting line 15. Preferably, however, they are located directly on the pump 1 or 1 a,

( ¹ ^ 25 e.g. on their connecting line connection pieces 26 a or 26 b.

The closer the pressure holding valve 18 a or 18 b is to the

The closer the pump inlet valve 10 or the pump outlet valve 11 is, the faster the pump 1 is ready for operation,

i.e., the shorter the interval between the start of pump 1 and the reaching of the intended negative or positive pressure in line 15.

Because the respective valve sealing surfaces 19 A and

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19 E in the closed position are practically in the undeflected position of the valve tongue 21 or 22, these valve tongues 21, 22 do not need to perform a sharp, especially not a double bend in their closed position _t as This would be the case for sealing surfaces that are opposite to the Level of the valve plate. Achieving a bypass with a simple movement of the valve tongues 21, 22 improves the service life of these valves, which are in any case a replacement part in such pumps.

The formation of the bypass-like leakage points _r with the help of corresponding notches 25 has the following ^ advantages: The cross-sectional area or the desired The amount of permeability per unit of time varies for the leakage points 17 depending on their use and size. It is therefore relatively easy to give the bypass-like leakage points 17 favorable dimensions adapted to the respective requirements, even if the basic pump type is initially designed uniformly. Accordingly, different, favorable modes of operation of the pump 1 can be achieved relatively easily with the help of appropriately adapted notches 25.

/· 25 As already mentioned, the design of the pump 1 according to the invention makes it easier to start up, so that a smaller motor 9 is required. This is not only cheaper to manufacture but also has smaller dimensions, which is advantageous for the entire pump 1. 30

All features described above and/or listed in the claims can be essential to the invention individually or in any combination with one another.

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- Protection claims -

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Claims (8)

Protection claims /■'ν 1 - Pump with pump inlet and pump outlet valves controlled by the pressure differences of their gaseous conveying medium, at least one of which is connected to a connecting line to a pressure vessel system, characterized in that a leak point (17) which is bypass-like even in the valve closed position and a pressure holding valve (18) are provided for this purpose on the pump inlet and pump outlet valve (13, 14) and in the connecting line (15) for the pressure vessel system. 2. Pump according to claim 1, in which the pump inlet and/ _or pump outlet valve is (are) essentially each formed by a valve tongue cooperating with a valve sealing point, expediently forming part of a valve plate, characterized in that the respective valve sealing surface (19) in the closed position is approximately in the undeflected position of the valve tongue (21, 22) and that the respective bypass-like leak point (17) is formed by at least one recess in the valve sealing surface (19), which slightly projects radially beyond the valve tongue at least at one point. /2 3· Pump according to one of claims 1 to 3, characterized in that the pressure holding valve (18 a, 18 b) is designed as a check valve. 4. Pump according to one of claims 1 to 3, characterized in that the pressure holding valve (18) is mounted near the associated pump inlet or pump outlet valve (13 or 14), expediently on the pump (1) or on its connecting line connection piece (26). 5. Pump according to one of claims 1 to 4, characterized in k ^ ■'■ . characterized in that it is designed as a preferably connecting rod-driven diaphragm pump (1, 1 a) and preferably its pump inlet and/or its pump outlet valve (13; 14) is designed as a check valve. 6. Pump according to one of claims 1 to 5, characterized in that it is designed as a vacuum pump (Fig. 2) and is connected with its system connection line (15 a) to a vacuum container (16) or similar vacuum vessel system and that the associated pressure holding valve (18 a) is located on the pump in the immediate vicinity of the suction connection (10). ²⁵ 7. Pump according to one of claims 1 to 5, characterized characterized in that it, designed as a pressure pump (Fig. 3), is connected by its system connection line (15 b) to a pressure vessel (27) or similar pressure vessel system and that the associated pressure holding valve (18 b) is located in the immediate vicinity of the pressure connection (11) on the pump. 8. Pump according to one of claims 1 to 7, characterized in that at least one, preferably all? 35 /3 bypass-like leaks (17) from a | Notch (25) is (are) formed, which expediently I the associated valve tongue (21 and/or 22) radially j at least in one place slightly above. : (H. Schmitt) Patent Attorney IU 16 20 25 30 35