EP0733179A1 - A passive three-way control valve and a coupling device including said valve - Google Patents

Abstract

A passive three-way control valve includes a first, a second and a third pipe section (11, 12, 13) which are connected to a common distribution chamber (7). A valve flap (14) is pivotally mounted in the distribution chamber (7) so as to be able to seal against a first or a second seat (120, 130) which surrounds the chamber inlet of the second and the third pipe section (12, 13), respectively. The first pipe section (11) forms an outlet port (1) and the second and the third pipe sections (12, 13) form valve inlet ports. The valve flap (14) is adapted to take smoothly a position between the seats (120, 130) in response to the flows through the inlet ports (2, 3). The flap (14) is adapted to seal fully against the seat of the pipe section through which the flow is zero.

Description

A PASSIVE THREE-WAY CONTROL VALVE AND A COUPLING DEVICE

INCLUDING SAID VALVE

The invention relates to a passive three-way control valve of the kind defined in the preamble of the dependent Claim directed to the valve. The invention also relates to a heating and ventilating circuit which includes such a three- way valve and which is of the kind defined in the preamble of the dependent Claim directed to the circuit.

A circuit which occurs frequently in heating and ventilating systems, particularly liquid circuits, is one in which a connection conduit which incorporates a processing unit, such as a heat-exchanger, is connected in series in a circuit, wherein a bypass conduit or shunt extends between the two positions at which the connecting conduit is connected to the circuit. In order to control or regulate the flow of medium through the unit/heat-exchanger, there is required, in principle, a controllable three-way valve means and the application of a fluid drive pressure generated by a main pump.

The flow of medium through the processing unit/heat-exchanger of such an arrangement will vary radically in many operation- al situations. A conventional three-way valve has difficulty in managing the control or adjustment required in the event of such radically varying flows, because it is necessary to design the three-way valve, i.e. select a three-way valve, which is adapted to the largest flow concerned, although the valve will then be too large for the smallest flow, resulting in poor authority.

Coupling devices of the kind concerned normally include a pump incorporated in said circuit and a pump or a drive- pressure means incorporated in the connecting conduit, wherein the three-way valve means may include a conventional three-way valve in the connection between the downstream end connections of the bypass conduit. Alternatively, the three- way valve means may include a check valve in the bypass conduit and a control valve in the connecting conduit.

Three-way valve means are significantly complex and also relatively expensive. Furthermore, conventional three-way valve means have poor valve authority when the primary and secondary sides are of different magnitudes.

An object of the invention is therefore to provide a simple passive three-way control valve which will operate without remote control and power supply and which can be used effectively as a three-way valve means in a circuit of the kind described, for instance. This object is achieved with the valve defined in the independent Claim directed to a three-way valve, and with the coupling device defined in the independent Claim directed to the coupling.

The inventive passive three-way valve provides an important advantage over conventional three-way valves, because when connected in a circuit similar to the inventive coupling device, the valve obtains a function similar to a three-way valve having different valve coefficient values, i.e. pressure losses, depending on the path taken by the water through the valve.

Adjustment to the water mixing temperature at port 1 is accurate and quick, even when the flows in the primary and secondary circuits are of different magnitudes.

Another important characteristic of the invented valve is that the valve will adapt smoothly to the flow in the circuit (secondary side) and to the flow in the connecting conduit (the primary side). The valve is designed so that its port connecting with the primary side will be fully closed when the flow from the primary side is zero. Furthermore, the valve port connecting with the bypass conduit is designed to be fully closed when the flow from the primary side is equally as large as the flow on the secondary side. This closure of the ports in said two positions or states prevents water mixing losses and unintentional heat losses from the heat-exchanger/processing unit as a result of a small flow leaking through the connecting conduit, at least when the flow through said conduit is regulated with the aid of a flow variable pump.

The inventive valve defined in the Claims includes a first, a second and a third pipe section which adjoin one another to form a common flow distribution chamber in which a valve flap is pivotally mounted such as to be brought by an inflow of fluid through the second pipe section to a position adjacent a seat which belongs to the third pipe section, and to be brought by an inflow of fluid through the third pipe section to a position adjacent a seat which belongs to the second pipe section, wherein the outflow passes through the first pipe section. The flap is pivotally mounted in a position that lies adjacent that part of the second and the third pipe section located commonly furthest in the upstream direction, and extends towards the first pipe section so as to take a pivotal position which depends on the relative flows from the second and the third pipe sections.

The valve flap of the inventive valve is arranged so that it can be brought into sealing abutment with respective seats, so as to fully close the third pipe section and the second pipe section respectively. In this regard, the second and the third pipe sections may be directed so that the third pipe section will be fully closed when the flow therethrough is zero. Complete closure of the pipe section can be achieved through the medium of separate closure means arranged to hold the flap in a closed position with a slight holding force. When the flow through the third pipe section is equally as large as the flow exiting through the first pipe section, the flap is intended to fully close the second pipe section. The desired working method can be established securely by providing corresponding means in the valve. These means may include a magnetic strip or the like mounted on the periphery of the flap and functioning to pull the flap into sealing contact with respective seats with a slight force when the flap/magnetic strip is brought to a position in the vicinity of a respective seat.

As an alternative to a magnetic strip, there may be used pre- tensionable spring devices which are released from their tensioned state upon contact and which when the valve flap is activated entrain said flap and hold the flap in sealing abutment with the adjacent seat with a given spring force, said spring arrangement being retensioned as the flap is driven away from its seat.

Another alternative is one in which said means includes a projection, such as a wing, on at least one main surface of the flap. This wing may be adapted to prevent the occurrence of flap-lifting sub-pressures in the passing flow, or may be designed to be driven by the passing flow in a manner to establish a torque or rotary moment which swings the flap towards its closed position. When the valve is appropriately orientated, the flap is able to act on one seat with a slight force under the action of gravity.

Thus in preferred embodiments the inventive valve is able to ensure complete blocking of the third pipe section when the flow therein is zero, and the second pipe section can be fully closed when the flow through the first and the third pipe sections are of equal magnitude.

The inventive coupling device, or circuit means, defined in the Claim directed to the coupling includes a connecting conduit which incorporates a processing unit and which is connected in series in a circuit, wherein a bypass conduit extends between the two locations at which the connecting conduit is connected to the circuit, wherein the circuit includes a pump, and wherein the connecting conduit includes a control valve or a flow regulatable pump, and wherein an inventive passive three-way control valve is connected to the coupling location between the outlet end of the bypass conduit and the circuit and the connecting conduit respec¬ tively.

Further developments of the invention are defined in the following dependent Claims.

The invention will now be described in more detail with reference to exemplifying embodiments thereof and also with reference to the accompanying drawings.

Fig.1 illustrates schematically an inventive coupling device which includes an inventive passive three-way control valve.

Fig. 2 illustrates another inventive coupling device which includes the inventive valve.

Figs. 3, 4 and 5 illustrate the inventive control valve in three different working positions.

Fig. 6 illustrates another embodiment of the valve.

Fig. 7 illustrates an alternative arrangement for holding the sealing flap of the valve in sealing engagement with the valve seat with a slight force.

Fig. 3 illustrates a first embodiment of a passive three-way control valve 10 which can be used, for instance, in coupling devices of the kind illustrated in Figs. 1 and 2, wherein the coupling device according to Fig. 1 is representative of control situations in which the inventive control valve finds favourable use. A primary circuit 20 is comprised of a connecting conduit 21 which incorporates a heat-exchanger 23 and a controllable pump 22. The connecting conduit 21 is in series with a secondary circuit 40 comprised of a circuit conduit 41 which incorporates a pump 42 which may be, but need not be, a regulatable pump, and a heat-exchanger 43, wherein a bypass conduit 30 is arranged parallel with the heat-exchangers 23 and 43. The valve 10 is connected to the junction point between the conduits 21, 41 and the downstream end of the bypass conduit 30, through the medium of valve ports 3, 1 and 2 respectively.

It can be assumed that the heat-exchanger 23 includes a refrigerating or cooling apparatus having a narrow terapera- ture range, i.e. a maximum temperature of 16°C and a minimum temperature of 14°C. Cold is taken from a cold source, which may be comprised, either directly or indirectly, of cold ambient air. The cold source is illustrated with the heat- exchanger 23 and its temperature varies in accordance with the outdoor temperature from +7°C to +14°C. The flow from the primary circuit 21 needed to cool the liquid in the secondary circuit 40 will thus vary radically.

Because the valve 10 includes a flap 14 which can be activat- ed by the flows through the ports 2 and 3, the valve will adapt smoothly to the flow through the valve ports 2 and 3, wherein the pump 22 regulates the flow in the primary circuit for transference of the cold required by the secondary circuit.

Fig. 2 illustrates a circuit which is alternative to the circuit shown in Fig. 1, and one of normal skill in this art will understand that the control valve 22' is able to control the flow through the conduit 21 provided that the conduit is acted upon by a drive pressure from a main pump, which may be common to many bypasses or shunts. Thus, if desired, the primary circuit 20 may incorporate a pump for applying a drive pressure to the liquid in said circuit, although such a pump need not be flow-regulatable.

Prior to the invention, the coupling device illustrated in Fig. 2 was constructed by mounting a check valve in the bypass conduit, therewith obviating the need for a three-way valve at the connection of the bypass conduit to the conduits 21, 41.

A coupling device corresponding to that shown in Fig. 1 has earlier been constructed by including a conventional control¬ lable three-way valve instead of the valve 10, and by applying a drive pressure in the primary circuit. This drive pressure is normally established with the aid of a simple pump which is not flow-variable.

As will be seen from Fig. 3, the valve 10 is constructed from three pipe sections 11, 12, 13 which are joined together to form a central distribution chamber 7. The pipe sections 11, 12, 13 define the valve ports 1, 2, 3. The ports 2 and 3 are provided at the inlet to the chamber 7 with annular sealing seats 120 and 130 respectively. A flap 14 is pivotally mounted on a pivot shaft 15 located in a region of the distribution chamber 7 in which the pipe sections 12, 13 together form inner corners. The flap 14 can swing freely about its pivot shaft 15 into sealing abutment with the seats 120, 130.

When the valve is orientated in the manner shown in Fig. 3, the flap 14 is driven against the valve seat 120 by the force of gravity.

The flap 14 may conveniently have a small wing-like device 16 on the side thereof proximal to the port 3.

It will be seen from Fig. 3 that the flap 14 has a pivot angle of about 60° between the seats 129, 130, which define an angle of about 75° with the axis direction of respective ports. In the embodiment illustrated in Fig. 3, the pipe sections 11 and 13 are mutually coaxial and extend perpendic¬ ular to the pipe section 12.

The wing 16 on the flap 14 has particular utility when the flap is in the position shown in Fig. 4. In the Fig. 4 illustration, it can be assumed that the flow through the port 2 is zero. Because the flow cross-section decreases in regard of the flow that passes through the ports 3 and 1, there is a tendency for the pressure to drop on the upper side of the flap 14. The wing 16 then functions to establish an eddy current or vortex which counteracts this lifting tendency. The subflow impinging on the wing 16 also exerts a force on the wing 16 which extends at a distance from the pivot shaft 15 and results in a torque which drives the flap 14 against the seat 120.

Fig. 5 illustrates a flow situation in which the flow through the port 3 is zero. The inflow through the port 2 pivots the flap 14 in a clockwise direction; the centripetal force of the flow deflected from the port 2 to the port 1 will thus drive the flap 14 against the seat 130, and when the flap includes the wing-like device 17 said device will be acted upon by a subflow from the port 2 so as to exert a rotary moment of force, or torque, around the pivot shaft 15 and therewith drive the flap 14 into further abutment with the seat 130.

In the embodiment illustrated in Fig. 6, each seat 120, 130 is provided with a magnet 52 on the part thereof which is distal from the pivot shaft 15. The flap 14 includes a ferromagnetic element which coacts with the magnet 52 in each end position of the flap 14. The mutual coaction of the elements 51, 52 serves to hold the flap in sealing abutment with a respective seat with a slight force, even though the flow decreases through those ports in which the flow is not zero. In the aforesaid case, the flap 14 may nevertheless remain in its end position, irrespective of the orientation of the valve.

Fig. 6 can be said to illustrate means for holding the flap in its respective end positions with a weak force, with the aid of a magnetic device. Fig. 7 illustrates a corresponding mechanical device 60 which includes a spring 63 which acts on the end of an lever 65 which is pivotally mounted on a shaft 66 and which has two mutually perpendicular arms 61, 62 on the distal end of the lever relative to the spring 63. The lever 65 is able to pivot between two end positions, of which one is shown in Fig. 7, wherein the arm 61 presses the flap 14 against the seat 120 under the action of the spring 63. When the flap 14 is moved away from the seat 120 by the action of flow through the port 2, the lever 65 is rotated anti-clockwise around the shaft 66 while compressing the spring 63, wherewith the spring 63 is pivoted around its support point until the spring 63 lies in a direction towards the shaft 66. Continued rotation of the lever 65 around the shaft 66 in an anti-clockwise direction causes the spring 63 to expand and to drive the lever 65 further in an anti-clock¬ wise direction until the arm 61 strikes against a shoulder or ledge 64, wherewith the arm 62 is exposed for activation by the flap 14, so as to move the arm clockwise around the shaft 66 beyond the dead-point position of the spring 63, so that the spring 63 will clamp the flap 14 firmly against the seat 120, through the medium of the lever arms 65, 61.

Fig. 8 illustrates another mechanical arrangement whose driving force is based on the force of gravity and which includes a lever arm 71 which is preferably located external¬ ly of the valve and which terminates at right angles to the pivot shaft 15, for instance. A weight 72 is conveniently mounted on the outer end of the lever arm 71. The lever arm is intended to lie essentially in a vertical plane when the flap 14 is in an intermediate position between the seats 120, 130. The position of the lever arm/arm is preferably selected to generate the same flap-abutment force against both seats.

The lever arm and the weight can be omitted in a variant of the embodiment illustrated in Fig. 8 when the two seats 120, 130 are each caused to lie on a respective side of a vertical plane passing through the pivot shaft 15. The force of gravity acting on the centre of gravity of the flap will thereby drive the flap into contact with respective seats. The purpose of the various devices for holding the flap in sealing contact with respective seats is to prevent the flap from unintentionally leaving its seat through which the flow is zero and therewith unintentionally establishing a flow through this seat due to unintentional limitation of the flow through the other seat.

In the case of the Fig. 8 embodiment, the lever arm 71 is preferably mounted outside the valve so as to indicate the position of the flap and therewith provide an indication of the working state of the valve.

Claims

1. A passive three-way control valve including a first, a second and a third pipe section (1, 2, 3) which are connected to a common distribution chamber (7), characterized by a valve flap (14) which is movably mounted in the distribution chamber (7) so as to be able to seal against a first or a second seat (120, 130) which surrounds the chamber inlets of respective second and the third pipe section (12, 13), wherein the first pipe section (11) forms an outlet port (1) and the second and the third pipe sections (12, 13) form valve inlet ports; and in that the valve flap (14) is adapted to smoothly adopt a position between the seats (120, 130) in response to the flows through the inlet ports (2, 3) , wherein the flap (14) is intended to seal fully against the seat of the pipe section through which the flow is zero.

2. A valve according to Claim 1, characterized in that the second and the third pipe sections (12, 13) are directed to enable the flow passing through the valve to drive the flap into sealing abutment with a respective seat (120, 130) behind which the flow is zero.

3. A valve according to Claim 1, characterized in that the valve is adapted to be orientated so that the flap will be driven gravitationally against one of the seats with a weak force.

4. A valve according to any one of Claims 1-3, character- ized by holding devices (51, 52; 60; 70) which function to hold the flap (14) in sealing contact with either of its seats (120, 130) with a slight force.

5. A valve according to any one of Claims 1-4, character- ized in that the flow through the valve is intended to be deflected by the flap (14), whereby the flap (14) is driven against the seat of the port that has the smallest flow.

6. A valve according to any one of Claims 1-5, character¬ ized in that the flap carries a wing-like device (16) which functions to reduce any subpressure that tends to arise as a result of a higher liquid speed on said flat surface.

7. A valve according to any one of Claims 1-6, character¬ ized in that the flap (14) is pivotally mounted in the chamber (7) such as to swing smoothly to a flow-dependent angular position between the seats.

8. A liquid circuit coupling device including a connecting conduit which incorporates a processing unit, such as a heat- exchanger, and which is connected in series to a circuit which includes a heat-exchange device and a pump, wherein a bypass conduit extends between the two mutual connections of the connecting conduit and the circuit conduit, characterized in that a passive three-way control valve according to any one of Claims 1-7 is mounted in the downstream connection of the bypass conduit (30) to the circuit conduit and the connecting conduit, wherein the outlet port (1) of the three- way valve (10) is connected to the circuit conduit; and in that the connecting conduit includes means (22, 22') for regulating the flow to one inlet port (3) of the three-way valve (10).

9. A coupling device according to Claim 7, characterized in that the control device (22) is a flow-regulatable pump.

10. A coupling device according to Claim 7, characterized in that the control device is a control valve (22') incorpo¬ rated in the connecting conduit, wherein the drive pressure acting on the liquid through the connecting conduit is obtained from a main pump.