Multiway valve with a removable exhaust wall

Abstract: A multiway valve for controlling the flow of a pressure medium from at least one delivery port to at least one exhaust port or supply port comprising a valve housing (1) having a substantially cylindrical axial bore (2) with a plurality of annular steps forming inner chambers (4a, 4b and 5a, 5b and 6) for connecting said ports, a spool arrangement for switching the flow of the pressure medium between said ports guided axially movable in said axial bore (2), whereby the spool arrangement including two valve spools (9a, 9b) arranged coaxial in tandem and which are independently axially slidable within the axial bore (2), at least one drive piston (12a, 12b) for axially shifting each valve spool (9a, 9b) upon engagement with a control pressure. A common exhaust chamber (6) is disposed next to the inner ends of both valve spools (9a, 9b) in the centre of the axial bore (6) to provide a connection with the at least one exhaust port (8a, 8b), furthermore, a removable exhaust wall (13) for dividing the exhaust chamber (6) in two parts is disposed in the common exhaust chamber (6) between the inner ends of both valve spools (9a, 9b) to direct the main exhaust air stream from each valve spool (9a, 9b) directly to the at least one exhaust port (8a, 8b).

Description: Field of the invention This invention relates to a multiway valve for controlling the flow of a pressure medium. More particularly, the present invention relates to a multiway valve with a movable inner spool for switching the flow of a pressure medium, e.g. pressed air, between outer ports. Especially, the invention relates to two 3/2-way valves integrated in a 5/2-or 5/3-way valve housing. Background of the invention Such valves are known from DE 44 00 760 C2 and from EP-A-898 103. The disclosed multiway valve comprises a valve housing, wherein an axially extending bore with a plurality of annular steps forming inner chambers is provided, wherein a valve spool arrangement is located, which is able to be moved longitudinally under the action of a control pressure by drive pistons in order to influence the supply of an actuating fluid to two delivery ports. The valve spool arrangement comprises two separate valve spools of which each is associated with one of said two separate delivery ports, and which are arranged coaxial in tandem in the valve bore extending from one end to the other end, same being able to be independently shifted longitudinally upon application of a suitable control pressure on a respective drive piston. It is in this manner that the function of two separate multiway valves is connected together in a single multiway valve housing. The two valve spools arranged in the common valve housing provide a respective 3/2-way valve function, each valve spool having its own exhaust port associated with it, while the two valve spools are preferably provided with a common supply port, which is disposed next to the inner ends of both valve spools in the centre of the axial bore. The known multiway valve described above is designed in a manner that the two valve spools are able to be interchanged so that in place thereof, if required, a conventional single piece valve spool may be employed in order to realise the function of a 5/2- or 5/3-way valve. Furthermore, it is common knowledge for a person skilled in the art to arrange the ports of a multiway valve - or its corresponding chambers inside the valve housing - in a manner that the central port serves to a common exhaust port (or chamber) for two integrated 3/2-way valve functions. In this case the exhaust port is flanked on either side, as considered along the valve bore in the housing, by a respective one of the both delivery ports, which are followed by further one of two supply ports. Hereby, in the common exhaust chamber the exhaust air from one of the two 3/2-valves can affect the other 3/2-valve, so that the other valve generates an undesired output signal. It is the aim of the present invention to provide a multiway valve which in contrast to the prior art provides a reliable separation of different integrated valves, so that in a common housing the respective valve spools can operate independently. Summary of the invention This aim is obtained in a multiway valve of the above-mentioned kind by using the features of the characterising portion of claim 1. Thus the invention basis on a common exhaust chamber which is disposed next to the inner ends of both valve spools in the centre of the axial bore to provide a connection with the at least one exhaust port, working together with a removable exhaust wall for dividing the exhaust chamber in two parts. The exhaust wall is disposed in the common exhaust chamber between the inner ends of both valve spools to direct the main exhaust air stream from each valve spool directly to the at least one exhaust port. So the present invention avoid an undesired output signal using an easy solution for a reliable separation of the both integrated 3/2-way valves. The both spools of the two integrated 3/2-way valves do not influence each other, because the main exhaust stream goes directly to the exhaust port. The exhaust wall forces the exhaust air to go down to the exhaust port instead of reaching an open output on the other valve spool. The exhaust wall does not have to be absolutely air tight. Its main purpose is to guide the main exhaust air stream in the desired direction. Preferably, the removable exhaust wall is shaped like a thin disk. It can be useful that the removable exhaust wall is disposed in a groove moulded on the inner surface of the common exhaust chamber in order to provide a simple solution for fixing the exhaust wall inside the exhaust chamber. The exhaust wall might be removable from the groove through the exhaust port or in another suitable manner. In a further advantageous development of the invention the common exhaust chamber is connected to the exhaust port by two separate exhaust channels. It is also possible to provide two exhaust ports for each exhaust channel. These both channels go into the respective part of the chamber in order to support the guide function of the wall. In a preferred embodiment of the invention the two valve spools of the two 3/2-way valve are interchangeable by a spool arrangement comprising only one single piece valve spool to provide a 5/2- or 5/3-way valve under the condition that the exhaust wall is removed. So it is possible to change the valve function only by changing the spool arrangement. The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the enclosed drawings. Brief description of the drawings Fig.1 is a cross-sectional view of a multiway valve according to the present invention with two 3/2-way valve functions produced by two independently operating valve spools in one valve housing. Fig.2 is a cross-sectional view of a multiway valve according to the present invention after the two valve spools of Fig.1 have been replaced by an single piece valve spool so that a 5/2-way valve function is created. Detailed description of the Drawings The pneumatic multiway valve shown in Fig.1 has a block-shaped oblong valve housing 1. The valve housing 1 has an axial bore 2 with a plurality of annular steps forming inner chambers 3a, 3b and 4a, 4b and 5a, 5b and 6. The chambers 4a and 4b are connected with corresponding outer supply ports 7a and 7b. The chambers 5a and 5b are connected with outer delivery ports (not shown). The central chamber 6 is connected with two parallel outer exhaust ports 8a and 8b. For switching the flow of pressured air between said ports two valve spools 9a and 9b are axially guided in said bore 2. The valve spools 9a and 9b are arranged coaxial in tandem in a manner that they are independently axially slidable within the axial bore 2. So the above described arrangement provides two 312-way valves in one valve housing 1. On two opposite front sides 10a and 10b of the valve housing 1 are disposed caps 11a and 11 b respectively for sealing the axial bore 2. At the two opposite front sides 10a and 10b there is a respective cylindrical control chamber 3a and 3b, which is able to be supplied with a control fluid under a control pressure in order to shift the valve spool 9a and 9b by means of drive pistons 12a and 12b respectively in the axial direction relatively to the bore 2 for switching the fluid flow. The common exhaust chamber 6 is disposed next to the inner ends of both valve spools 9a and 9b. A removable exhaust wall 13 is disposed in the common exhaust chamber 6 between the inner ends of both valve spools 9a and 9b. The exhaust wall 13 divides the exhaust chamber 6 in two parts to direct the main exhaust air stream from each valve spool 9a and 9b directly to the exhaust ports 8a and 8b. The disk-shaped exhaust wall 13 is disposed in a groove 14 moulded on the inner surface of the common exhaust chamber 6. As shown in Fig.2 the two valve spools 9a and 9b are interchangeable by a spool arrangement comprising only one single piece valve spool 15 to provide a 5/2-way valve under the condition that the exhaust wall 13 is removed from the groove 14. The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various way within the scope of protection defined by the appended patent claims.

Claims: A multiway valve for controlling the flow of a pressure medium from at least one delivery port to at least one exhaust port or supply port comprising: a valve housing (1) having a substantially cylindrical axial bore (2) with a plurality of annular steps forming inner chambers (4a, 4b and 5a, 5b and 6) for connecting said ports, a spool arrangement for switching the flow of the pressure medium between said ports guided axially movable in said axial bore (2), whereby the spool arrangement includes two valve spools (9a, 9b) arranged coaxial in tandem, which are independently axially slidable within the axial bore (2), at least one drive piston (12a, 12b) for axially shifting each valve spool (9a, 9b) upon engagement with a control pressure, characterized in that a common exhaust chamber (6) is disposed next to the inner ends of both valve spools (9a, 9b) in the centre of the axial bore (6) to provide a connection with the at least one exhaust port (8a, 8b), a removable exhaust wall (13) for dividing the exhaust chamber (6) in two parts is disposed in the common exhaust chamber (6) between the inner ends of both valve spools (9a, 9b) to direct the main exhaust air stream from each valve spool (9a, 9b) directly to the at least one exhaust port (8a, 8b). A multiway valve according to claim 1, characterized in that the removable exhaust wall (13) is shaped like a disk. A multiway valve according to one of the preceding claims, characterized in that the removable exhaust wall (13) is disposed in a groove (14) moulded on the inner surface of the common exhaust chamber (6). A multiway valve according to one of the preceding claims, characterized in that the common exhaust chamber (6) is connected to the at least one exhaust port (8a, 8b) by separate parallel exhaust channels for each valve spool (9a, 9b). A multiway valve according to one of the preceding claims, characterized in that the exhaust wall (13) is removable from the groove (14) through the exhaust port. A multiway valve according to one of the preceding claims, characterized in that said two valve spools (9a, 9b) are interchangeable by a spool arrangement comprising only one single piece valve spool (15) to provide a 5/2- or 5/3-valve under the condition that the exhaust wall (13) is removed. A multiway valve according to one of the preceding claims, characterized in that said at least one delivery port and said at least one exhaust port and said at least one supply port are arranged essentially in one plane at the valve housing (1), so that the valve housing. (1) is suitable in a valve subassembly for mounting on a fluid manifold element.

Inventors: FAGERSTROEM PETER, FAGERSTROEM, PETER, Fagerström, Peter
Applicants: BOSCH REXROTH TEKNIK AB
Application year: 2001
Main classification: F15B13
IPC codes: F16K11, F15B13, F16K27, F16K3, F16K31