[0001] The invention relates to a three-way valve comprising: a body and one or more first, second and third ports coupled to one another.

[0002] In known pressure medium operated systems, a commonly encountered problem is that of a so-called return flow. For example, if a double-acting hydraulic cylinder (63/45) is driven back and forth at a 50 l/min output, a flow of about 100 l/min is generated at a return stroke of the cylinder in a line from the cylinder via a directional control valve to a tank. If the directional control valve is a ½ inch valve, or if the cylinder is coupled by a ½" quick connector to a hydraulic system of a tractor, for instance, the rated flow of the directional control valve and the quick connector being about 50 l/min, the amount of oil discharging from the cylinder causes unnecessary energy consumption and slows down the movement.

Brief description

[0003] The valve according to the invention is characterised by what is disclosed in the characterising parts of the independent claims. Other embodiments of the invention are characterised by what is disclosed in the other claims.

[0004] Inventive embodiments are also disclosed in the specification and drawings of this application. The inventive contents of the application may also be defined in ways other than those described in the following claims. The inventive contents may also consist of several separate inventions, particularly if the invention is examined in the light of expressed or implicit sub-tasks or in view of obtained benefits or benefit groups. In such a case, some of the definitions contained in the following claims may be unnecessary in view of the separate inventive ideas. Features of the different embodiments of the invention may be applied to other embodiments within the scope of the basic inventive idea.

[0005] The idea underlying the invention is that when the valve stem of the valve is in its first position, the pressure medium flows, controlled by the valve stem, from the first port to the second port, but not to the third port, but when the valve stem is in its second position, the pressure medium flows, controlled by the valve stem, from the second port to the first and the third port. [0006] The advantage is that the valve alleviates the aforementioned return flow problem or even eliminates it completely, enabling the system to be designed and dimensioned according to the output of the pump. In such a case, the control valves and other components in the system may be dimensioned significantly smaller, their costs thus being lower since not all components have to be dimensioned according to the maximum flow.

Brief description of the figures

[0007] Some embodiments of the invention are explained in closer detail in the accompanying drawings, in which

Figure 1 shows an operating principle of a valve according to the invention,

Figure 2 shows a coupling of the valve according to the invention to a pressure medium system,

Figure 3 shows a second coupling of the valve according to the invention to a pressure medium system,

Figure 4 shows a third coupling of the valve according to the invention to a pressure medium system,

Figures 5a and 5b show a fourth and a fifth coupling of the valve according to the invention to a pressure medium system,

Figures 6a to 6d are schematic sectional side views showing a three-way valve according to the invention,

Figure 7 is a sectional side view showing a second three-way valve according to the invention,

Figure 8 is a schematic sectional side view showing a third three- way valve according to the invention,

Figure 9 is a schematic sectional side view showing a fourth three- way valve according to the invention, and

Figure 10 is a sectional side view showing a fifth three-way valve according to the invention.

[0008] For the sake of clarity, the figures show some embodiments of the invention in a simplified manner. In the figures, like reference numerals identify like elements.

Detailed description

[0009] Figure 1 shows an operating principle of a valve according to the invention. The valve 100, shown in Figure 1 in broken line, is a so-called three-way valve which comprises a first port 1 , a second port 2, and a third port 3. The valve 100 allows a pressure medium to flow through in two directions: a first flow direction A and a second flow direction B. The valve 100 opens the third port 3 only during a flow running in the second flow direction B. The third port 3 is closed during a flow running in the first flow direction A. The valve 100 is constructed such that when the flow or a pressure difference is small or zero, the third port 3 is closed or open. The valve 100 changes its state when the flow direction or the pressure difference changes.

[0010] The ports 1 , 2, 3 may be constructed in a different order, and the number of ports 1 , 2, 3 may be one or more. The valve 100 may comprise a plurality of first, second and/or third ports, enabling a plurality of actuators to be coupled to the same valve. When a plurality of given ports are provided, some of them may be plugged permanently or temporarily in order to achieve a desired operation.

[0011] The valve operates on various liquid or gaseous pressure mediums. According to an idea, the pressure medium is a hydraulic liquid.

[0012] For instance when the valve is coupled to a hydraulic system and when oil is flowing in the second flow direction B, the oil is allowed to be discharged from the valve 100 via the second and the third port 2 and 3.

[0013] When the flow direction of the oil changes to the first flow direction A, the oil flows through the first port 1 into the valve 100 but is allowed to be discharged from the valve 100 only via the second port 2. The third port 3 is then closed.

[0014] Figure 1 shows, in broken line, a second embodiment of the second flow direction B wherein the pressure medium enters the valve 100 via the third port 3 and is discharged via the first and the second port 1 , 2 and, also in broken line, a second embodiment of the flow direction A wherein the pressure medium enters the valve 100 via the first port 1 and is only discharged via the port 3.

[0015] Figure 2 shows a coupling of the valve according to the invention to a pressure medium system. The valve 100 may be arranged to alleviate or eliminate the so-called return flow problem in cylinder actuators, for instance. In Figure 2, the valve 100 is arranged in connection with a hydraulic cylinder 18. The valve 100 enables the hydraulic system to be designed and dimensioned according to the output of the pump. It is to be noted that no pump is shown in the figure. In such a case, the control valves and other com- ponents in the system may be dimensioned significantly smaller since they do not have to be dimensioned according to the maximum flow of the system. This enables less expensive components to be used.

[0016] According to an embodiment, the hydraulic cylinder 18 (here- inbelow cylinder) is double-acting and driven back and forth at a 50 l/min output. In such a case, a return flow of about 100 l/min is generated in a line from the cylinder 18 via a directional control valve to a tank at a return stroke. The directional control valve 19 is selected to be a valve whose rated flow is about 50 l/min. When the valve 100 is arranged in the system such that the return flow is parallel with the second flow direction B, the third port 3 is open during the return flow. The third port 3 may be connected for instance to a quick connector whose rated flow is about 50 l/min. This enables a return flow of 100 l/min to be arranged via the first port 1 and the third port 3. This enables a considerable amount of energy and time to be saved because the flow resistance is now lower.

[0017] Figure 3 shows a second coupling of the valve according to the invention to a pressure medium system. The valve 100 may be used as an unloading flow valve in motor drives or it may be coupled to relieve a return flow pressure.

[0018] In an embodiment, a trailer or another corresponding tool of a tractor or a corresponding work machine is provided with a drive used by a hydraulic motor 20. When the work machine moves the tool faster than the speed at which oil is fed to the hydraulic motor 20, the valve 100 allows the oil to enter a so-called unloading flow. When the speed of the work machine slows down sufficiently, the hydraulic motor 20 starts driving again. The valve 100 operates in a similar manner also when the work machine is used for reversing the tool and also when the hydraulic drive is set in reverse. The advantage is that the hydraulic motor 20 does not decelerate as the speed increases and the drive does not have to be deactivated as the speed increases or when reversing.

[0019] The solution shown in Figure 3 comprises two valves 100 and their check valves 21 coupled to the third ports 3, in which case it operates in the above-described manner both when driving forward and while reversing as well. [0020] In another embodiment, the unloading flow is coupled to be operating in one direction only, enabling one check valve 21 and one valve 100 to be omitted.

[0021] Figure 4 shows a third coupling of the valve according to the invention to a pressure medium system. The valve 100 may also be used as a so-called rapid movement valve, in which case pressure medium being discharged from the side of a piston rod 22 of the cylinder 18 becomes directed to the opposite side of the cylinder's piston, i.e. the side of the larger chamber, in addition to the output of the pump. Herein, the third port 3 thus opens up in order to feed the pressure medium via the valve 100 to the first port 1 .

[0022] The advantage is that when desired, the power and rate of travel of the cylinder 18 can be made the same in both directions of the cylinder 18, or that it is possible with a piston rod 22 which is thin with respect to the diameter of the piston to make the movement occurring in a direction of the side of the piston rod 22 of the cylinder, i.e. so-called +(plus)movement, significantly faster than the opposite, i.e. so-called -(minus)movement. Applications of such an embodiment are provided for instance in control or transfer cylinders, or in cylinders which, for instance owing to the risk of buckling, are at least mainly used by pulling and the aim is to make the +movement fast.

[0023] Figures 5a and 5b show a fourth and a fifth coupling of the valve according to the invention to a pressure medium system.

[0024] The valve 100 may also be used as a control valve. The valve 100 may be arranged for instance such that when running the pressure medium through the valve 100 in the first flow direction A, only actuators coupled to the second ports 2 are used, whereas when running the pressure medium through the valve 100 in the second flow direction, actuators coupled to the second and the third ports 2 and 3 are used. The actuator may be a motor 20 or a cylinder 18, for example.

[0025] In the embodiment shown in Figure 5a, the actuator controlled in the above-described manner is the right-hand cylinder 18. In Figure 5b, the actuator is the motor 20. The control takes place by means of the directional control valve 19.

[0026] The advantage is that by using one directional control valve and by coupling the valve 100 appropriately to the system, a grip, transfer, etc. function of a separate actuator coupled to the movement of the actual work cylinder in the other direction, for instance, is achieved. [0027] Figures 6a to 6d are schematic sectional side views showing a valve according to the invention. It is to be noted in this connection that the structural details of the valves shown in the following figures are only some examples of feasible embodiments thereof. It is thus clear that the details of the valve in terms of its dimensions and design, for instance, may also be implemented otherwise.

[0028] The valve 100 has a body 4 comprising one or more parts, at least one first 1 , second 2, and third 3 port coupled to one another in a pressure-medium delivery connection through a channel 5 arranged in the body 4 for delivering the pressure medium.

[0029] The valve 100 is also provided with a valve stem 6 arranged to be movable in a stem space 7 formed in said channel 5.

[0030] The channel 5 delivering the pressure medium comprises a stem space 7 connecting the first and the second port 1 , 2, and a side channel 8 coupled to the third port 3 and connecting with the stem space 7 through an opening 9 arranged in a wall of the latter.

[0031] The valve stem 6 is set to change its location between a first and a second position due to the influence of a pressure difference caused by said pressure medium.

[0032] The valve stem 6 comprises a check valve 12 arranged to open when the pressure medium flows in the second flow direction, i.e. from the second port 2 to the first port 1 . The check valve 12 may have a spring member 17 which forces a valve cone 23 against an opening 15 in the valve stem.

[0033] The location of the third port 3 may determine whether or not the third port 3 is open or closed when no flow runs through the valve 100 or when the flow is little. In the following, the operation of the valve 100 shown in Figures 6a to 6d will be discussed.

[0034] When no flow runs through the valve 100 or when the flow is little, the valve 100 and the valve stem 6 in particular are in their position shown in Figure 6a. In such a case, the third port 3 is open, enabling a flow between it and the second port 2. If the third port 3 were placed more to the right, i.e. closer to the first port 1 , it would be closed by the valve stem 6.

[0035] In Figure 6b, the valve 100 is in a state wherein the valve stem 6 is in its first position and the pressure medium is allowed to flow, controlled by the valve stem 6, in the first flow direction A from the first port 1 to the second port 2, the valve stem 6, however, preventing a flow to the third port 3.

[0036] In practice this is implemented such that the valve stem 6 has moved, forced by the pressure medium flowing from the first port 1 , to the left, to an end of the stem space 7. Further, the pressure of the pressure medium has overcome the spring force of the spring member 17, which has resulted in the valve cone 23 having become detached from the opening 15 in the valve stem and the pressure medium being allowed to flow to the second port 2. A wall part 10 of the valve stem instead prevents a flow to the third port 3.

[0037] In Figure 6c, the valve 100 is in a state wherein the valve stem 6 is in its first position and the pressure medium is allowed to flow from the second port 2 to the first 1 and the third port 3.

[0038] In practice this is implemented such that the valve stem 6 has moved, forced by the pressure medium flowing from the first port 1 , to the right, to an end of the stem space 7. Consequently, the valve stem 6 has moved away from the front of the third port 3. The valve cone 23 has settled facing a counter member 24 arranged in connection with the first port 1 so as to prevent the valve cone 23 from closing the opening 15 in the valve stem. In this case, the counter member 24 is a pin arranged in the second port 1 , but of course it may also be implemented otherwise.

[0039] According to an idea, the ports 1 to 3 of the valve 100 may be formed by detachable nipples 25. The valve 100 shown in Figures 6a to 6d is implemented according to this idea. In Figure 6c, the first port 1 is formed by a nipple 25 which comprises said counter member 24. In Figure 6d, this nipple 25 forming the first port 1 is replaced by an ordinary double nipple. In such a case, the valve 100 operates as an ordinary three-way valve since the flow from the first port to the second port 2 closes the third port 3, and the flow from the second port 2 to the third port 3 closes the first port 1 . Such an embodiment is particularly useful when the valve 100 is used for instance in controls or as a rapid movement valve in a line on the piston stem side.

[0040] Figure 7 is a schematic sectional side view of a second three-way valve according to the invention.

[0041] Unlike in the previous example, no check valve 12 of the valve stem is provided but the check valve 21 is arranged between the first and the second port 1 , 2, in a check valve channel 13 passing the stem space 7. The valve stem 6 is a simple "mug" which reciprocates in the stem space 7 and whose wall part 10 is provided with at least one flow aperture 16.

[0042] In the situation shown in the figure, the pressure medium may flow from the second port 2 to the third port 3 and via the check valve channel 13 and the check valve 21 to the first port.

[0043] The stem space 7 comprises an enlarged part 1 1 arranged to deliver the pressure medium flow coming from the first port 1 to the second port 2. Said pressure medium flow pushes the valve stem 6 to the right in figure, in which case the valve stem 6 opens up flow access to the enlarged part 1 1 . The pressure medium flows through the flow aperture 16 then residing at the enlarged part 1 1 , into the valve stem 6 and further to the second port 2. At the same time, the wall part 10 of the valve stem closes the third port 3.

[0044] Figure 8 is a schematic sectional side view of a third three- way valve according to the invention. The valve 100 comprises a plurality of first, second and third ports 1 , 2, 3.

[0045] The valve 100 is herein implemented as a so-called cartridge valve. This means that the body 4 of the valve is cylindrical in its external appearance and arrangeable in a casing or drilling provided therefor. Such an actuator into which the valve 100 may thus be integrated may be for instance an end piece of a hydraulic cylinder or a body of a directional control valve. It is to be noted in this connection that other embodiments of the valve described in the present description may also be implemented as a cartridge valve. It is further to be noted that the valve 100 according to Figure 8 may naturally be implemented as a separate component of its own, i.e. in a manner similar to that shown in the other figures. It is yet to be noted that all embodiments of the valve 100 may also be implemented such that a part of another actuator serves as their body 4, which is appropriately provided with a space for the stem 6 and the ports 1 , 2, and 3.

[0046] The valve stem 6 comprises an opening 15 to enable it to move around a flow pipe 14 in a longitudinal direction thereof. In addition, the valve stem 6 comprises a partition wall 26 slidably arranged on an outer surface of the flow pipe 14.

[0047] To the valve stem 6 are coupled two spring members 17 to keep the valve stem 6 in the position shown in Figure 6, in a so-called free state. In such a free state, the third port 3 is open. By placing the third port 3 otherwise it would be able to close it in the free state. [0048] It is to be noted that instead of two spring members, it is possible to use one or even two more spring members.

[0049] The flow pipe 14 is arranged between the first and the second port 1 , 2, and it comprises flow apertures 16 extending through its wall. In addition, the flow pipe has a partition wall 25 dividing the pipe into two parts, a first one being connected to the first port 1 and a second one to the second port 2.

[0050] The pressure medium flow from the first port 1 moves the valve stem 6 to the left in the figure, in which case the third port 3 closes. At the same time, a flow path via the flow apertures 16, passing the partition wall 25, opens up. In such a case, the pressure medium may flow from the first port 1 to the second port 2, but not to the third port 3.

[0051] The pressure medium flow from the second port 2 moves the valve stem 6 to the right in the figure, in which case the third port 3 opens up. At the same time, a flow path via the flow apertures 16, passing the partition wall 25, opens up to the first port 1 . The pressure medium may thus flow from the second port 2 to the first port 1 and the third port 3.

[0052] Figure 9 is a schematic sectional side view showing a fourth three-way valve according to the invention. According to an idea, the channel 5 may be not only straight but also asymmetrical. Figure 9 shows such an embodiment of the valve 100. In this embodiment, the spring member 17 forces the valve stem 6 against a point of change in the asymmetrical channel 5. In the situation shown in Figure 9, the pressure medium flow from the second port 2 is allowed from the first port 1 to the second port 2, but not to the third port 3. When the flow direction changes and the force caused by the flow overcomes the spring force of the spring member 17, the pressure medium flow is allowed to flow from the second port 2 to both the first and the third port 1 : to the first port 1 via the flow apertures 16 and to the third port 3 past an end of the valve stem 6.

[0053] It is to be noted in this connection that the spring member 17 is not an essential part of the valve 100 according to the invention: depending on the application, the desired movement of the valve stem 6 may be achieved by means of the pressure of the pressure medium exclusively.

[0054] Figure 10 is a sectional side view showing a fifth three-way valve according to the invention. This is highly similar to the valve shown in Figures 6a to 6d, differing, however, in that the valve stem 6 and the check valve 12 of the valve stem provided therein are arranged to operate reversely. In the state shown in Figure 10, the pressure medium is allowed to flow from the second port 2 to the first and the third port 1 , 3 or, correspondingly, the pressure medium from the third port 3 is allowed to flow to the second and the first port 2, 3. Instead, the pressure medium flow from the first port 1 moves the valve stem 6 to the left in the figure, past the third port 3, in which case the pressure medium is allowed to the third port 3, but not to the second port 2.

[0055] It is to be noted that for instance if the valve shown in Figure 10 were coupled to the arrangement of Figure 2, the port 1 would be coupled to the directional control valve 19, and the port 3 to the cylinder 18, enabling an additional tank line to be arranged from the port 2 to alleviate the return flow.

[0056] In some cases, features disclosed in this application may be used as such, regardless of other features. On the other hand, when necessary, features disclosed in this application may be combined in order to provide different combinations.

[0057] In summary, the valve according to the invention is characterised in that it comprises: a body, one or more first, second and third ports coupled to one another by a channel arranged in the body for delivering a pressure medium, and a valve stem arranged to be movable in said channel, the three-way valve being arranged to allow a pressure medium flow in at least two flow directions so that in a first flow direction the valve stem is in its first position and the pressure medium flows, controlled by the valve stem, from the first port either to the second port or the third port, the valve stem, however, preventing a flow either to the third port or the second port, respectively, and in a second flow direction the valve stem being in its second position and the pressure medium flowing, controlled by the valve stem, from the second port to the first and the third port or from the third port to the first port and the second port, and that the valve stem is set to change its location between the first and the second position due to the influence of a pressure difference caused by said pressure medium.

[0058] The drawings and the related description are only intended to illustrate the idea of the invention. It will be apparent to a person skilled in the art that the invention is not restricted to the above-described embodiments disclosing the invention through some examples, but various modifications and different applications of the invention are feasible within the inventive idea defined in the accompanying claims.

[0059] Reference numerals

1 first port

2 second port

3 third port

4 body

5 channel

6 valve stem

7 stem space

8 side channel

9 opening in stem space wall

10 wall part of valve stem

1 1 enlarged part of stem space

12 check valve of valve stem

13 check valve channel

14 flow pipe

15 opening in valve stem

16 flow aperture

17 spring member

18 cylinder

19 directional control valve

20 motor

21 check valve

22 piston rod

23 valve cone

24 counter member

25 partition wall

26 partition wall of valve stem

100 valve

A first flow direction

B second flow direction