GB1598997A

GB1598997A - Change-over valve

Info

Publication number: GB1598997A
Application number: GB8720/78A
Authority: GB
Original assignee: PARISIENNE OUTILLAGE; Compagnie Parisienne dOutillage a Air Comprime SA
Current assignee: PARISIENNE OUTILLAGE; Compagnie Parisienne dOutillage a Air Comprime SA
Priority date: 1977-03-09
Filing date: 1978-03-06
Publication date: 1981-09-30
Also published as: IT7821003A0; FR2383378A1; FR2383378B1; IT1093754B; BE864528A; ES467703A1; SE7802658L; DE2809778A1; SE434085B; LU79191A1; NL7802614A

Description

(54) CHANGE-OVER VALVE (71) We, Society Anonyme dite COMPAGNIE PARISENNE D'OUTILLAGE A AIR COMPRIME, a French Body Corporate of, l ibis, rue Roquépine, 75008 PARIS, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the follow ing statement:- The invention relates to a seated change-over valve, which is particularly but not exclusively, intended for use in pneumatic equipment.

The present invention provides a seated change-over valve comprising a body with an inlet port for a fluid under pressure, two outlet ports to be selectively put into communication with the inlet port, and at least one exhaust port to be put into communication with that one of the outlet ports which is not selected to be in communication with the inlet port, and control means movable relative to the body to select one or other of the outlet ports for communication with the inlet port, wherein the control means comprises:: a piston-operated slide member having two extreme positions, each corresponding to selection of a respective one of the outlet ports; first and second valve disks each controlling communication between the inlet port and a respective one of the outlet ports, each of the valve disks being independently slidable along the slide member and being resilently biassed to engage a fixed seat integral with the body to prevent communication between the corresponding outlet port and the inlet port; and first and second shutter means, integral with the piston-operated slide member, each shutter means having a seat for engaging a corresponding one of the valve disks on the same side of the disk as the disk engages the corresponding fixed seat, communication between the corresponding outlet port and the, or one of the, exhaust port(s) being prevented when the seat of the shutter means engages the valve disk:: the arrangement being such that when the slide member is in either one of its extreme positions one of the valve disks is urged by the corresponding shutter member seat away from its fixed seat against the resilient bias, thereby ensuring communication between corresponding outlet port and the inlet port while preventing communication between the said outlet port and the, or one of the, exhaust port(s), and at the same time the other valve disk is not in contact with the other shutter member seat, resulting in it being urged by the resilient bias into contact with the fixed seat thereby ensuring communication between the other outlet port and the, or one of the, exhaust port(s) while preventing communication between the said outlet port and the inlet port;; the arrangement further being such that when the slide means moves from one of its extreme positions to the other, the valve disk that was initially not in contact with its fixed seat comes into contact therewith before the other valve disk is urged away from its fixed seat, thereby ensuring that the inlet port is momentarily prevented from communicating with either of the outlet ports.

Preferably the piston-operated slide member includes two integrally mounted pistons each of which has one face co-operating with a drive chamber that receives a fluid pressure signal to select a corrresponding outlet port, and an oppositely directed face co-operating with a feed-back drive chamber that is arranged to receive fluid under pressure from the outlet port corresponding to the other piston.

The disks may be provided on one face with sealing means having two concentric ridges thereon, the outer one of which co-operates with the corresponding fixed seat to close the associated outlet port under the action of the pressure of the supply fluid on the opposite face of the valve disk, while the inner ridge co-operates with the corresponding shutter seat.

The valve may include two independent exhaust ports, each outlet port being associated with a corresponding one of the exhaust ports.

An embodiment of the invention is described by way of example with reference to the sole figure of the accompanying drawing which is a schematic vertical section through a changeover valve in accordance with the invention, and in one of its operating positions.

In the figure, the reference 7 designates the tubular body of a change-over valve having its ends closed by covers 6. In the mid-portion of its lateral wall the body includes an inlet port 1 for admitting fluid under pressure and leading to an admission chamber 10. On either side of the port 1 there are outlet ports 2 and 4 for the fluid under pressure and exhaust ports 3 and 5 associated with the outlet ports 2 and 4, each of these ports being adjacent a respective outlet chamber 20 or 40 or exhaust chamber 30 or 50.

A pistonsperated slide member, generally designated 8, is disposed on the axis of the tubular body 7. It is constitutedbya cylindrical axle 80 connecting two identical parts each of which comprises a cylindrical body 83 or 84 whose end facing the mid-portion constitutes a shutter 85 or 86 and whose other end constitutes a piston 81 or 82.

Each shutter includes an identical internal channel 87 or 88 which provides communication between the outlet chamber 20 or 40 and the associated exhaust chamber 30 or 50 when in the open position.

That face of each of the pistons 81 and 82 which is adjacent to the corresponding cylindrical body 83 or 84 is subject to pressure in a feed-back drive chamber 73 or 74; each of these feed-back drive chambers is connected by ducting 18 or 19 to the outlet chamber which is situated on the opposite side of the change-over valve. The other face of each piston is disposed opposite one of the covers 6 and is subjected to pressure from a drive chamber 71 or 72 connected via a port 12 or 14 to a source of driving fluid.

Two valve disks 6a and 6b are slidably mounted on the cylindrical axle 80, and are free to move from one position in which their inner faces meet a middle stop 70 disposed in the admission chamber 10 and an opposite position in which their outer faces engage a seat 7a or 7b disposed between the admission chamber 10 and the outlet chamber 20 or 40.

Each disk has a seal 9 with two concentric ridges on its outer face opposite the seat, the outer ridge 91 cosperating with the fixed stop constituted by the seat facing it and the inner ridge 92 co-operating with the shutter facing it. Further a sliding seal 93 ensures sealing along the axle 80. A compression spring 61 is interposed between the two disks 6a and 6b.

Also, the change-over valve includes a mechanical locking device. To this end, each cover is provided with a stub axle 26 directed towards the facing piston. Near to its end, this axle has two peripherial ball bearings 27 diametrically opposed to each other and subject to the action of a compression spring 28. The balls 27 are free to slide on an internal cam surface 25 which is symetrical about an inversion point 24.

Operation of the change-over valve is as follows: Assume the valve is put under fluid pressure without any control input while it is in the position which is shown in the figure.

The fluid under pressure arrives in the admission chamber 10 via the port 1 and is applied against the internal face of the disk 6a which is in the closed position by virtue of its ridge 91 being in contact with the seat 7a. Since the disk 6b is open, the fluid can flow towards the outlet chamber 40 which communicates with the outlet port 4 and also supplies the feed-back drive chamber 73 of the slide member 8 via the ducting 18. This, by means of the shutter 86 pressing against the rim 91 of the disk 6b closes the path via the channel 88 to the exhaust chamber 50.

The shutter 85 of the slide member 8 is at a distance from the disk 6a. The fluid in the outlet chamber 20 is thus in communication via the channel 87 with the exhaust chamber 30 which has the effect of depressurising the chamber 20 as well as the port 2, the ducting 19 and the feed-back drive chamber 74.

To change over the valve, a control pulse in the form of a pressurized driving fluid is applied to the drive chamber 71 via the port 12. This causes the slide member 8 to move towards the right bringing the shutters 85 and 86 which are rigidly connected together. The prssure in the chamber 10 acting on the inner face of the disk 6a keeps it sealed, while the disk 6b closes communication between the admission chamber 10 and the outlet chamber 40. Since communication between the admission chamber 10 and the outlet chamber 20 remains closed, a closed transition period is obtained during which there is no outlet path from the admission chamber.

Continuing movement of the shutters then establishes communication between the outlet chamber 40 and the exhaust chamber 50, and then the shutter 85 which has approached the disk 6a while reducing the cross-section of the passage between the outlet chamber 20 and the exhaust chamber 30 closes communication therebetween. After this the shutter 85 is pressed against the ridge 92 of the disk 6a and pushes this disk to end the closed transition period by establishing communication between the admission chamber 10 and the outlet chamber 20.

The feed-back drive chamber 74 is then supplied via the ducting 19 from the outlet chamber 20 which locks the valve in the desired end position, thereby making it unnecessary to continue the supply the drive chamber 71.

The reverse movement is obtained according to the same process but starting with a control signal at the port 14 of the drive chamber 72.

The mechanical locking device operates by its balls 27 sliding on the cam 25 against the action of the spring 28. After passing the central inversion point 24 the movement of this device is transmitted to the slide member 8 with which the cam 25 is integrally mounted. This device enables the movement of the slide member 8 to be completed as a function of the last order received and maintains it in the corresponding final position even in the absence of fluid under pressure.

WHAT WE CLAIM IS:

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. to an admission chamber 10. On either side of the port 1 there are outlet ports 2 and 4 for the fluid under pressure and exhaust ports 3 and 5 associated with the outlet ports 2 and 4, each of these ports being adjacent a respective outlet chamber 20 or 40 or exhaust chamber 30 or 50. A pistonsperated slide member, generally designated 8, is disposed on the axis of the tubular body 7. It is constitutedbya cylindrical axle 80 connecting two identical parts each of which comprises a cylindrical body 83 or 84 whose end facing the mid-portion constitutes a shutter 85 or 86 and whose other end constitutes a piston 81 or 82. Each shutter includes an identical internal channel 87 or 88 which provides communication between the outlet chamber 20 or 40 and the associated exhaust chamber 30 or 50 when in the open position. That face of each of the pistons 81 and 82 which is adjacent to the corresponding cylindrical body 83 or 84 is subject to pressure in a feed-back drive chamber 73 or 74; each of these feed-back drive chambers is connected by ducting 18 or 19 to the outlet chamber which is situated on the opposite side of the change-over valve. The other face of each piston is disposed opposite one of the covers 6 and is subjected to pressure from a drive chamber 71 or 72 connected via a port 12 or 14 to a source of driving fluid. Two valve disks 6a and 6b are slidably mounted on the cylindrical axle 80, and are free to move from one position in which their inner faces meet a middle stop 70 disposed in the admission chamber 10 and an opposite position in which their outer faces engage a seat 7a or 7b disposed between the admission chamber 10 and the outlet chamber 20 or 40. Each disk has a seal 9 with two concentric ridges on its outer face opposite the seat, the outer ridge 91 cosperating with the fixed stop constituted by the seat facing it and the inner ridge 92 co-operating with the shutter facing it. Further a sliding seal 93 ensures sealing along the axle 80. A compression spring 61 is interposed between the two disks 6a and 6b. Also, the change-over valve includes a mechanical locking device. To this end, each cover is provided with a stub axle 26 directed towards the facing piston. Near to its end, this axle has two peripherial ball bearings 27 diametrically opposed to each other and subject to the action of a compression spring 28. The balls 27 are free to slide on an internal cam surface 25 which is symetrical about an inversion point 24. Operation of the change-over valve is as follows: Assume the valve is put under fluid pressure without any control input while it is in the position which is shown in the figure. The fluid under pressure arrives in the admission chamber 10 via the port 1 and is applied against the internal face of the disk 6a which is in the closed position by virtue of its ridge 91 being in contact with the seat 7a. Since the disk 6b is open, the fluid can flow towards the outlet chamber 40 which communicates with the outlet port 4 and also supplies the feed-back drive chamber 73 of the slide member 8 via the ducting 18. This, by means of the shutter 86 pressing against the rim 91 of the disk 6b closes the path via the channel 88 to the exhaust chamber 50. The shutter 85 of the slide member 8 is at a distance from the disk 6a. The fluid in the outlet chamber 20 is thus in communication via the channel 87 with the exhaust chamber 30 which has the effect of depressurising the chamber 20 as well as the port 2, the ducting 19 and the feed-back drive chamber 74. To change over the valve, a control pulse in the form of a pressurized driving fluid is applied to the drive chamber 71 via the port 12. This causes the slide member 8 to move towards the right bringing the shutters 85 and 86 which are rigidly connected together. The prssure in the chamber 10 acting on the inner face of the disk 6a keeps it sealed, while the disk 6b closes communication between the admission chamber 10 and the outlet chamber 40. Since communication between the admission chamber 10 and the outlet chamber 20 remains closed, a closed transition period is obtained during which there is no outlet path from the admission chamber. Continuing movement of the shutters then establishes communication between the outlet chamber 40 and the exhaust chamber 50, and then the shutter 85 which has approached the disk 6a while reducing the cross-section of the passage between the outlet chamber 20 and the exhaust chamber 30 closes communication therebetween. After this the shutter 85 is pressed against the ridge 92 of the disk 6a and pushes this disk to end the closed transition period by establishing communication between the admission chamber 10 and the outlet chamber 20. The feed-back drive chamber 74 is then supplied via the ducting 19 from the outlet chamber 20 which locks the valve in the desired end position, thereby making it unnecessary to continue the supply the drive chamber 71. The reverse movement is obtained according to the same process but starting with a control signal at the port 14 of the drive chamber 72. The mechanical locking device operates by its balls 27 sliding on the cam 25 against the action of the spring 28. After passing the central inversion point 24 the movement of this device is transmitted to the slide member 8 with which the cam 25 is integrally mounted. This device enables the movement of the slide member 8 to be completed as a function of the last order received and maintains it in the corresponding final position even in the absence of fluid under pressure. WHAT WE CLAIM IS:

1. A seated change-over valve comprising a body with an inlet port for a fluid under pressure, two outlet ports to be selectively put into communication with the inlet port, and at least one exhaust port to be put into communication with that one of the outlet ports which is not selected to be in communication with the inlet port, and control means movable relative to the body to select one or other of the outlet ports for communication with the inlet port, wherein the control means comprises:: a piston-operated slide member having two extreme positions, each corresponding to selection of a respective one of the outlet ports; first and second valve disks each controlling communication between the inlet port and a respective one of the outlet ports, each of the valve disks being independently slidable along the slide member and being resilently biassed to engage a fixed seat integral with the body to prevent communication between the corresponding outlet port and the inlet port; and first and second shutter means, integral with the piston-operated slide member, each shutter means having a seat for engaging a corresponding one of the valve disks on the same side of the disk as the disk engages the corresponding fixed seat, communication between the corresponding outlet port and the, or one of the, exhaust port(s) being prevented when the seat of the shutter means engages the valve disk:: the arrangement being such that when the slide member is in either one of its extreme positions one of the valve disks is urged by the corresponding shutter member seat away from its fixed seat against the resilient bias, thereby ensuring communication between corresponding outlet port and the inlet port while preventing communication between the said outlet port and the, or one of the, exhaust port(s), and at the same time the other valve disk is not in contact with the other shutter member seat, resulting in it being urged by the resilient bias into contact with the fixed seat thereby ensuring communication between the other outlet port and the, or one of the, exhaust port(s) while preventing communication between the said outlet port and the inlet port;; the arrangement further being such that when the slide means moves from one of its extreme positions to the other, the valve disk that was initially not in contact with its fixed seat comes into contact therewith before the other valve disk is urged away from its fixed seat, thereby ensuring that the inlet port is momentarily prevented from communicating with either of the outlet ports.

2. A valve according to claim 1, wherein the piston-operated slide member includes two integrally mounted pistons each of which has one face co-operating with a drive chamber that receives a fluid pressure signal to select a corresponding outlet port, and an oppositely directed face co-operating with a feed-back drive chamber that is arranged to receive fluid under pressure from the outlet port corresponding to the other piston.

3. A valve according to claim 1 or 2, wherein each valve disk is provided on one face with sealing means having two con-centric ridges thereon, the outer one of which co-operates with the corresponding fixed seat to close the associated outlet port under the action of the pressure of the supply fluid on the opposite face of the valve disk, while the inner ridge co-operates with the corresponding shutter seat.

4. A valve according to any preceding claim, including two independent exhaust ports, each outlet port being associated with a corresponding one of the exhaust ports.

5. A valve according to any preceding claim including a mechanical device for latching the valve in each of its extreme positions.

6. A seated change-over valve substantially as herein described with reference to and as illustrated in the accompanying drawing.