Valve arrangement

Abstract

 The invention relates to valve arrangement for controlling hydraulic components such as power cylinders, hydraulic engines, which valve arrangement comprises a directional valve (10) with connecting channels (18) and (19) wherein said directional valve is arranged to control the flow direction of a fluid in said channels (18, 19). According the invention a number of first and second dual port shut off valves of the seat type (20a, 30a, 40a, 20b, 30b, 40b) are connected to said channels. These dual port shut off valves are connectable to a hydraulic component for controlling said component. The valve arrangement further comprises a manoeuvring unit (60) for activation of the directional valve (10) and the dual port shut off valves.

Description

Background and Prior Art

[0001] The present invention relates to a valve arrangement for the control of hydraulic components such as power cylinders and motors, especially at working vehicles for forestry, agriculture and constructional works. At said, so called, mobile hydraulics it is usual that the operator is not able to be placed in the immediate proximity to the core components of the hydraulics, whereby a need for remote control occurs. This is normally solved in that the operator actuates a system of valves for the hydraulic components, via a distance bridging manoeuvring device, which e.g. may comprise electrical switches and longer or shorter electric cables, by means of which electro magnets are activated, which magnets actuates the change-over movements of the valves. The valves are normally mounted at a metal block which comprises sophisticated channel systems. The blocks are comparatively difficult to manufacture with a reasonable reliability of service. This known solution is complex and expensive, especially when large block valve units are demanded in small numbers. This technical field is also illustrated in the patent application with No: SE 0302743.

Summary of the invention

[0002] A purpose of the present invention is to provide en enhanced valve arrangement for the control of hydraulic components. It is another purpose to provide a valve arrangement which solves the above described problems and which constitutes a simple, flexible and economical arrangement of valves for the control of hydraulic components and which in addition is very functional and reliable in service.

[0003] These and other purposes are achieved by a valve arrangement of the kind defined in the preamble of claim 1 and which exhibits the special technical features indicated in the characterizing portion of the claim. The valve arrangement according to the invention is intended for controlling hydraulic components such as power cylinders and motors. The valve arrangement comprises a directional valve and a first and a second channel, which channels are connected to the directional valve. Said directional valve is arranged to control the flow direction of a fluid in said channels. The valve arrangement further comprises a number of first and second hydraulic valves arranged in pairs. The first hydraulic valve in each pair is connected to the first channel and arranged to be connected to a first port of a hydraulic component. The second hydraulic valve in each pair is connected to the second channel and arranged to be connected to a second port of the corresponding hydraulic component. Said first and second hydraulic valves are composed of dual port shut off valves of the seat type. At least one hydraulic valve in each pair is arranged sealing in both fluid flow directions. The valve arrangement also comprises a manoeuvring unit for activation of the directional valve and of the first and second hydraulic valves. The invention provides a valve arrangement which is very simple in construction and reliable in service. The valve arrangement further exhibits very high flexibility and versatility. Grace to that any desired number of pairs of hydraulic valves readily may be connected to the first and second channel, it is very easy to adapt the valve arrangement to different applications where the number and type of the hydraulic components to be controlled varies largely. At an arrangement according to the invention, a number of unitary valves of very simple type is used, viz. dual port shut off valves of the seat type, which may be manufactured in large series at a reasonable cost. These dual port shut off valves have only two modes, either open for through flow of fluid or closed for through flow of fluid, at least in one of both flow directions. This in contrast to larger multi port valves, which are always designed as sliding valves. Seat valves may, in contrast to sliding valves, achieve complete sealing against fluid through flow and often provide a better functionality than sliding valves. The advantageous sealing of the dual port shut off valves according to the invention results inter alia in a god load supporting capability of the hydraulic components which are controlled by means of said valves.

[0004] Additional purposes and advantages of the invention will appear from the following description of embodiments and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In the following, some exemplifying embodiments of the invention are described, with reference to the drawings, in which:

Fig 1 is a schematic outline of a valve arrangement according to a first embodiment of the invention, which valve arrangement is illustrated as forming part of a hydraulic system.

Fig. 2 is a schematic outline corresponding to fig. 1 and illustrates a valve arrangement according to second embodiment.

Fig. 3 is a schematic outline which illustrates a manoeuvring unit comprised in a valve arrangement according to the invention.

Fig. 4 is a schematic outline corresponding to fig. 1 nd illustrates a valve arrangement according to third embodiment.

Fig. 5 is a schematic outline corresponding to fig. 1 and illustrates a further valve arrangement.

Fig. 6 is a schematic outline corresponding to fig. 1 and illustrates still a further a valve arrangement.

Description of embodiments

[0006] As an example of the invention the following is described: Fig. 1 illustrates a valve arrangement at which the hydraulic valves characterizing the invention are dual port shut off valves 20, 30 and 40 which, in this particular case, are of a certain type of seat valve which seals completely against fluid through flow in both directions. They are arranged to be changed over by means of electro magnets and they are completely closed by a spring force at an electrically inactivated mode. Fig. 1 further illustrates a directional valve 10 comprising a double 3-port valve, often referred to as a 6/2 valve and an hydraulic component in the form of a power cylinder 50 which is controlled by means of the valve arrangement.

[0007] Fluid is supplied to this directional valve at port 12a and exits the directional valve at port 12b, for being returned to the pressure pump 2 which provides said supply. Normally, this is carried out through a tank 1 and a filter. If said pump is of the non-load-sensing type, then a relief valve is advantageously inserted, which is kept open for fluid through flow by spring force at electrical inactivated mode, but which is closed by means of electrical activation when any component is to be driven. If the pump 2 is of the load sensing type, then a valve 4 which is closed in the electrical inactivated mode is inserted, which valve is opened by electrical activation when any component is to be driven. In order to achieve the intended effect at the later type of pump, with a flow which is well adapted for the components, a flow restriction 5, a signal line connected to the pump and a heavily restricted relief line 7 is normally required in practice. In fig. 4 possible alternative positionings of said auxiliary valves 3 and 4 are shown.

[0008] When the directional valve in fig. 1 is electrically inactivated, its actuating rod 15 is held in its upper position by a spring force from below, whereby its sealing tap 16a closes port 13a at the same time as tap 17a leaves port 14a open. The tap 16b closes port 13b and tap 17b leaves port 14b open. This in combination with the channels system indicated in fig. 1, which is connected to the directional valve, results in that fluid may flow out from the directional valve in channel 18 and in towards the directional valve in channel 19. When the directional valve 10 is electrically activated, the actuating rod 15 is pushed down by the electro magnet 15a, whereby the tap 17a closes port 14a at the same time as tap 16a opens port 13a. Tap 17b closes port 14b. This results in that fluid may flow out from the directional valve in channel 19 and in towards the directional valve in channel 18.

[0009] The manoeuvring unit 60 fig. 3 shows symbolically three 2-pole electrical switches 61, 62, 63 where the four points at the corners of each of the three symbolizes connection terminals for the three electrical cables that leads to the electro magnets of the valves. The H-formed part at the centre of each switch symbolizes a conducting contact part, which is movable upwards and downwards from a central position of repose. When the operator moves the contact part of the electrical switch 63 upwards and brings this in contact with said connection terminals the valves 40a and 40b are activated to the open position. Simultaneously, the relief valve is activated to closed position and the directional valve 10 remains inactivated, since the diode 65 blocks electrical current to this 10. This results in that fluid is supplied into the directional valve 10 at 12a, through this valve's 10 upper 3-port chamber and out at 14a via channel 18 through valve 40a out to a first port at the piston rod side of the cylinder 50. Through a second port, at the opposite side of the cylinder, the return fluid is delivered through valve 40b, further back through channel 19 into the directional valve 10 at 14b, through its lower 3-port chamber and back to tank 1, via port 12b. Thereby, the working cylinder is moved to retracting piston rod.

[0010] If the operator moves the contact part downwards, then 40a and 40b are activated to open position, the relief valve to closed position and the directional valve 10 to a position with depressed control rod 15. This result in that fluid is supplied into the directional valve 10 at 12a, further out at 13a, over to channel 19, through this and valve 40b, out to the piston side of cylinder 50. The opposite side of the cylinder 50, the piston rode side; delivers return fluid through valve 40a, further through channel 18, back into directional valve 10 at 13b and to tank 1 through 12b. Thereby, the power cylinder 50 moves with extracting piston rod.

[0011] If the operator leaves the contact part rest in the centre, the no valve is activated. Valves 40a, 40b then remains closed, whereby the power cylinder assumes a neutral fixed load supporting sate.

[0012] The manoeuvring unit 60 described at this example, constitutes merely one of several possible solutions for selectively and simultaneously controlling which valve that shall be activated and inactivated. At larger valve arrangement according to the invention, also 3-pole electrical switches, additional diodes, relays and processors may be utilized. At a valve arrangement according to the invention, also single acting power cylinders may be of interest. The piston rod may e.g. be driven out of a cylinder by a fluid via either of the valves 20b, 30b or 40b and flows back the same way when the piston rod is pressed back into the cylinder by an external force, such as the gravity. Corresponding valve, i.e. either of 20a, 30a or 40a may then normally be excluded. It may also be appropriate to let either of said valves to be excluded at simpler types of double acting components, where by one side of the component is directly connected e.g. to channel 18 and its other side to channel 19, via e.g. valve 40b. At such an instance only this valve 40b admits and blocks movement of e.g. a working cylinder.

[0013] The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

Claims

1. Valve arrangement for controlling hydraulic components such as power cylinders, hydraulic engines, which valve arrangement comprises

- a directional valve (10); and

- a first (18) and a second (19) channel, which channels are connected to the directional valve, wherein said directional valve is arranged to control the flow direction of a fluid in said channels (18, 19), characterized in

- a number of first (20a, 30a, 40a) and second (20b, 30b, 40b) hydraulic valves arranged in pair, wherein the first hydraulic valve (20a, 30a, 40a) in each pair is connected to the first channel and arranged to be connected to a first port of a hydraulic component, and the second hydraulic valve (20b _,30b, 40b) in each pair is connected to the second channel (19) and arranged to be connected to a second port of the corresponding hydraulic component;

- that said first and second hydraulic valves are composed of dual port shut off valves of the seat type (20a, 30a, 40a, 20b, 30b, 40b), whereof at least one hydraulic valve in each pair is arranged sealing in both fluid flow directions; and in

- a manoeuvring unit (60) for activation of the directional valve (10) and of the first and second hydraulic valves.

2. Valve arrangement according to claim 1, wherein the manoeuvring unit (60) is arranged such that activation of both the directional valve (10) and at least one of the first and second hydraulic valves (20a, 30a, 40a, 20b, 30b, 40b), is effected in one single moment.

3. Valve arrangement according to any of the preceding claims, wherein the manoeuvring unit (60) comprises electro magnets and electric switches for forming electrical circuits which drives the electro magnets.

4. Valve arrangement according to any of the preceding claims, wherein the directional valve (10) comprises a double 3-port valve, also denominated a 6/2 valve.

5. Valve arrangement according to any of the preceding claims, comprising a relief valve (3).

6. Valve arrangement according to any of the preceding claims, comprising a stop valve (4).

7. Valve arrangement according to any of the preceding claims, wherein the first channel (18) is a pressure channel and the second (19) channel is a return channel.

Drawing