EP0864752A2

EP0864752A2 - Control valve group for the continuous operation of a pumping element

Info

Publication number: EP0864752A2
Application number: EP98200757A
Authority: EP
Inventors: Giuseppe Rosa
Original assignee: Rosauto Srl
Current assignee: Rosauto Srl
Priority date: 1997-03-12
Filing date: 1998-03-10
Publication date: 1998-09-16
Also published as: ITMI970537A1; IT1290588B1; EP0864752A3

Abstract

A valve control group for the continuous operation of a fluid or liquid pumping element (11,12) by means of a control air feeding (13,14), comprising a first, at least three-way, valve element (16), which is also movable in a discharge position (19), and which normally connects a control air source (13, 14) and an inner control chamber (17) of said pumping element (11, 12). The valve element (16) is driven (in 22, 23, 24) by the air over-fed in said inner control chamber (17) to drive said pumping element. A throttling element (18) is placed between said first valve element (16) and said control air source (13, 14) and is connected to the discharge valve; said throttling element receives continuously an air feeding and, selectively, discharge air through a duct (21) from said first valve element (16). <IMAGE>

Description

The present invention refers to a control valve group for the continuous operation of a pumping element.

In the present art, the pumping element control, as a diaphragm pump or a single-acting cylinder or the like, used to feed a fluid or a liquid, comprises various valve groups which feed the control air therethrough.

In particular, in the diaphragm pumps, there is a need to make a hole in the diaphragm to place big washers or similar elements in order to assemble the diaphragm return elements.

The same need is present in the single-acting cylinders wherein a rod has to be provided in order to attach thereon a spring to return the piston to its initial position.

This return elements or springs of various kind are subject to wear and they can cause improper operation of the pumping element.

Further, the assembly of said return elements in the diaphragm pump or in the single-acting cylinder or in the like, causes an increase in production time and in the related costs.

The presence of these return elements and of the related assembly elements, as washers, causes also the need for a fine tuning of the control valve group, since it is needed a good sealing for the feeding air and for the fluid or liquid to be sucked and then pumped.

The general purpose of the present invention is to solve the mentioned technical problems, and also to overcome the above mentioned disadvantages related to the known art.

Another purpose is to realise a simpler structure both of the pumping elements and of their control valve group in a single, quite inexpensive, practical way and with good sealing properties.

In consideration of said purposes, according to the present invention, it was realised a control valve group for the continuous operation of a pumping element which has the features disclosed in the appended claims.

The structural and operational features of the present invention and its advantages in respect of the known art will be more evident from the following description, referred to the accompanying drawings, which show control valve groups realised according to the invention. In the drawings:

Figure 1 is a perspective, partial section view of a diaphragm pump connected to a control valve group for continuous operation according to the invention, said group is shown in a perspective, very schematic view, the whole apparatus is shown in a first working position;
Figure 2 is a circuit diagram equivalent to that of Figure 1 with a cylinder pumping element instead of the diaphragm pump, in the same position of Figure 1;
Figure 3 is the same perspective view of Figure 1 of a diaphragm pump connected to a control valve group for continuous operation according to the invention, shown in a second working position; and
Figure 4 is a circuit diagram equivalent to that of Figure 2 with a cylinder pumping element instead of the diaphragm pump, in the same position of Figure 3.

With reference to the drawings, numeral 10 indicates the control valve group for the continuous operation of the subject pumping element, said control group, in the illustrated examples, operates a diaphragm pump 11 or alternatively a pumping cylinder 12 respectively.

In figures 2 and 4 a source 13 feeds air through a duct 14, wherein a filter 15 is positioned, toward a first three-way or even alternatively five-way valve element 16.

This first valve element 16 is normally open and usually connects the control air valve 13 and an inner control chamber 17 of the

pump element

11 or 12, as shown in Figures 1 and 2.

Figures 2 and 4 show also that the first valve element 16 is driven by the air which is over-fed and does not operate the

pump element

11 or 12.

Further, a throttling element 18 is positioned between the first valve element 16 and the control air source 13, said throttling is usually connected to a discharge duct 19. In the shown example, the throttling element 18 receives, from a branch duct 20, part of the air feeding from source 13, from duct 14 and, selectively, the discharge air from the first valve element 16, when the same is driven in the discharge position through the duct 21. This driving action stops the air feeding to the inner control chamber 17 of the

pump element

11 or 12.

As an alternative the throttling element 18 can also be fed continuously from a source different from source 13 which feeds the valve element 16.

The throttling element 18 has, preferably, a Venturi arrangement connected to duct 21 for the discharge air from the first valve element 16, when it is driven in the discharge position.

This driving action, as said before, is realised by the air over-fed from duct 14 and it does not operate the

pumping element

11 or 12, when the same reaches the stroke end.

In fact, Figure 2 and 4 show the presence of a duct 22, downstream of the first valve element 16, on which duct a flow control device 23 is positioned. The flow control device 23 connects the inner control chamber 17 of the

pumping element

11 or 12 and the second valve element, indicated with numeral 24.

The second valve element 24 is normally closed and can be selectively connected to the control air source 13 through a further duct 25.

Further, when said second element is driven in said position, through a further duct 26, it drives the first valve element 16 in the discharge position.

The positions both of the first valve element 16 and of the second valve element 24 are defined by the cooperation of an

elastic element

27, 27a and of a

small control cylinder

28, 28a.

The valve element 16 and the

control cylinder

28, 28a can also be operated manually.

Both Figure 1 and Figure 2 show a first working phase of the control valve group for the continuous operation of a fluid or liquid pumping element by means of a control air feeding according to the invention.

It should be noted that the air feeding from source 13 is normally fed to the first valve element 16, the throttling element 18 and the second valve element 24.

In the position shown in this first phase, the first valve element 16 is normally open and the second valve element 24 is normally closed. The feeding air, coming from duct 14, goes through the first valve element 16 and arrives into the inner control chamber 17 of the

pumping element

11 or 12.

In this way the air, in the first example of Figure 1, moves the diaphragm 29 of the diaphragm pump 11 to the stroke end position; in the second example of figure 2 the air pushes a piston 30 of the pumping cylinder 12 to the stroke end position.

At this point, part of the feeding air goes through duct 22 and then, through the flow control device 23, feeds the small cylinder 28a connected to the second valve element 24 and drives its compartment motion.

It should be noted that up to this point the second valve element 24 is closed and that it blocks the connection between the air feeding duct 25 and the first valve element 16, as shown both in Figure 1 and in Figure 2.

As a consequence, the compartment of the second valve element 24 is now in the position shown in Figures 3 and 4. In this way, the second small cylinder 28 is activated and, since it is connected to the first valve element 16, drives its compartment from the normally open position to the one shown in Figures 3 and 4.

The compartment motion of the first valve element 16 closes duct 14 which feeds the air into the control chamber 17 of the

pumping element

11 or 12.

It is clear that in this first phase, during which the feeding air has pushed the diaphragm 29 of the diaphragm pump 11 or the piston 30 of the pumping cylinder 12 to the stroke end position, a pumping action has been realised.

The content of a second chamber 31 of the diaphragm pump 11 or of the pumping cylinder 12, in fluid or liquid form, has been discharged and pumped outside the pump.

This action is performed along arrow 32 through a hole or an outlet duct 33, provided with a single-acting valve 34 and obtained in the body of the pump and of the pumping cylinder.

In this moment the second working phase of the control valve group for the continuous operation of a pumping element of the present invention begins.

The first valve element 16 closes the connection of its compartment with the air feeding duct 14 and connects the pumping element and the discharge duct 21.

In this way, all the air exits from inside chamber 17 of the

pumping element

11 or 12. The throttling element 18, connected to the discharge duct, is already connected to the air feeding from duct 20. This throttling element 18, having the mentioned Venturi arrangement, favours the air discharge from the

pumping element

11 or 12.

Thanks to such Venturi arrangement the throttling element sucks and discharges said air into discharge duct 19, creating a vacuum inside chamber 17 of the

pumping element

11 or 12.

During this second phase, the air suction causes the backward motion of the diaphragm 29 of the diaphragm pump 11 or of the piston 30 of the pumping cylinder 12.

In this way a suction action of the fluid or liquid inside the second chamber 31 of the diaphragm pump 11 or of the pumping cylinder 12 is realised. This happens since the fluid or the liquid enters from outside along arrow 35 through a hole or an inlet duct 36, provided with a single-acting valve 37 and obtained on the body of the pump or of the cylinder, and the air fills the second chamber 31.

The small cylinder 28a, facilitated by the vacuum in the

pumping element

11 or 12, discharges its content through the flow control device 23.

Then, the compartment of the second valve element, pushed by the elastic element 27a, returns to its original position and closes the air flow going from duct 25 to the second small cylinder 28 of the first valve element 16.

In this way, also the first valve element 16 is in the rest position since the compartment is biased by its corresponding elastic element 27. The first valve element 16 is in its normally open position which connects the air feeding duct 14 from the source and the first chamber 17 of the

pumping element

11 or 12.

At this point the full cycle is repeated and the continuous operation is realised. It is possible, thanks to the presence of the flow control device 23 connected to the control inner chamber 17 of the

pumping element

11 or 12, to adjust the time duration of the cycles constituting the continuous operation.

The advantage of this valve group consists in the extreme easiness of production, without any operation on the diaphragm or on the piston of the pumping element.

From the above description, with reference to the Figures, it is evident that by applying a throttling element 18, having a Venturi arrangement, on the first valve element discharge will allow to have a fully pneumatic control also in a diaphragm pump.

By avoiding the realisation of holes in the diaphragm, the purpose mentioned in the description preamble is attained, i.e. the easy, less expensive production of the diaphragm pump.

In the same manner, also a single-acting cylinder or the like can be realised without stems or spring of a certain economic valve related both to production, assembly and maintenance.

Of course, the valve group embodiments, especially the driving part, can be different from the one shown as a non limiting example in the drawings.

The scope of protection of the invention is therefore defined by the appended claims.

Claims

A valve control group for the continuous operation of a fluid or liquid pumping element (11,12) by means of a control air feeding (13,14), characterised by comprising a first, at least three-way, valve element (16), which is also movable in a discharge position (19), and which normally connects a control air source (13, 14) and an inner control chamber (17) of said pumping element (11, 12), said valve element (16) is driven (in 22, 23, 24) by the air over-fed in said inner control chamber (17) to drive said pumping element, a throttling element (18) is placed between said first valve element (16) and said control air source (13, 14) and is connected to the discharge valve, said throttling element receives continuously an air feeding and, selectively, discharge air through a duct (21) from said fist valve element (16).
A valve control group according to claim 1, characterised in that said throttling element (18) is fed continuously by the same control air source (13, 14) which feeds the first valve element (16).
A valve control group according to claim 1, characterised in that said first valve element (16) is driven by means of a flow control device (23) and of a second valve element (24) normally closed, said flow control device (23) is positioned along the duct which connects said inner chamber (17) of said pumping element (11, 12) and said second valve element (24), which can be selectively connected to said control air source (13).
A valve control group according to claim 1, characterised in that said throttling element (18) has a Venturi arrangement connected to said duct (21) for said discharge air coming from said first valve element (16), whereby a vacuum is created inside chamber (17) of the pumping element (11, 12).
A valve control group according to claims 1 or 3, characterised in that said first valve element (16) and second valve element (24) are maintained in their two positions respectively by an elastic element (27, 27a) and by a small control cylinder (28, 28a) connected thereto.
A valve control group according to claim 1, characterised in that said pumping element is a diaphragm pump (11)
A valve control group according to claim 1, characterised in that said pumping element is a single-acting cylinder (12).