TECHNICAL FIELD

[0001] The present disclosure relates to a directional control valve system and in particular to a control section of such a system having tank channels that are fluidly connected in the control section, resulting in a reduction of the pressure drop within the directional control valve system during its operation.

BACKGROUND

[0002] In sectional hydraulic directional valve systems, pressurized oil is directed to one or more hydraulic consumers (e.g. actuator cylinders or hydraulic motors). A sectional directional valve system typically comprises an inlet section that is in turn connected to one or a series of control sections that are stacked next to and connected to each other. Each control section is dedicated to the control of a respective hydraulic consumer. Furthermore, a sectional directional valve system typically comprises an end section connected to the last of the control sections. The return oil from each one of the hydraulic consumers is normally sent back to its dedicated control section, wherefrom it is led through a separate tank channel to a tank.

[0003] In certain applications and load conditions, e.g., those with high return flows, it is important to keep the pressure drop in the return oil flow as low as possible to enable optimized manoeuvring characteristics and reduced energy losses.

SUMMARY

[0004] It is an object of the present disclosure to alleviate at least some of the mentioned drawbacks of the prior art and to provide a directional control valve system that reduces pressure loss in the tank channel for high return flow applications. This and other objects, which will become apparent in the following, are accomplished by a directional control valve system as defined in the accompanying independent claims.

[0005] The term exemplary should in this application be understood as serving as an example, instance or illustration.

[0006] The present disclosure is at least partially based on the realisation that hydraulically joining two parallel return channels allows for a lower return flow through the tank channels. This is beneficial since it reduces the resulting pressure loss of a high return flow from a hydraulic consumer.

[0007] The present disclosure is furthermore based on the realisation that hydraulically joining two adjacent tank channels, instead of replacing them with a single larger diameter tank channel, allows for a modularity of the system as control sections according to the present disclosure may be used together with sections belonging to the prior art, i.e. sections having two separated tank channels that are not connected to each other.

[0008] The proposed arrangement described below will contribute to lowering the pressure losses when the return oil passes through the tank channels in the directional valve system and the at least one control section thereof.

[0009] At least one advantage over the prior art is provided by a directional control valve system for controlling at least one hydraulic consumer having at least one consumer port, the system comprising: an inlet section, at least one control section, and an end section; wherein an inlet port is provided in the inlet section and/or end section; wherein at least one tank port is provided in the inlet section and/or end section; wherein the at least one control section comprises an inlet port channel fluidly connected to the inlet port of the inlet section and/or end section, a first tank channel and a second tank channel fluidly connected to the at least one tank port of the inlet section and/or end section, and a moveable valve member for controlling a flow of hydraulic fluid between the inlet port, the at least one tank port and the consumer port of the hydraulic consumer; wherein the at least one control section further comprises a cross channel passageway fluidly connecting the first tank channel and the second tank channel to each other.

[0010] At least one advantage over the prior art is provided by the cross channel passageway being arranged such that it balances a return flow from the at least one hydraulic consumer between the first tank channel and the second tank channel. The cross channel passageway does this by having a cross section that allows a hydraulic fluid flowing in one of the two tank channels to pass therethrough to the other tank channel and onwards to the tank port, thus balancing the total flow rate between the two tank channels.

[0011] The cross channel passageway is integrally formed with the control section, either by means of the cross channel passageway being cast in one piece with the control section, or by the cross channel passageway being formed by means of a subsequent machining step.

[0012] The cross channel passageway is closed to all but the first and second tank channel, such that it may better balance the flow rate therebetween. This means that there is no hydraulic connection between the cross channel passageway and other parts of the directional control valve system than the first and second tank channel.

[0013] The cross channel passageway is arranged such that it balances a return flow is to be interpreted as meaning that the cross channel passageway is arranged and dimensioned such that it allows a hydraulic fluid flowing in one of the two tank channels to pass therethrough, thus redirecting a portion of the flow from one tank channel to the other. This allows an unbalanced tank channel flow, in which one of the two tank channels has a higher return flow than the other, to be balanced such that the difference therebetween is reduced. By reducing the difference in return flow in the two tank channels, the total pressure loss of the hydraulic fluid is reduced.

[0014] At least one advantage over the prior art is provided by the first tank channel and the second tank channel of the at least one control section being open on both sides for connection to the inlet section, the end section, and/or another control section of the directional control valve system.

[0015] Thus, a modular system is achieved, a plurality of control sections may be arranged in series to form a system having the desired configuration.

[0016] At least one advantage over the prior art is provided by the movable valve member being moveable from (i) a neutral closed position to (ii) a first position opening a flow path between the consumer port and the inlet port channel; and (iii) a second position opening a flow path between the consumer port and the first tank channel or the second tank channel.

[0017] At least one advantage over the prior art is provided by the system being configured for controlling at least one hydraulic consumer having a first and a second consumer port, and the moveable valve member being configured for controlling a flow of hydraulic fluid between the inlet port, the at least one tank port and the consumer ports of the hydraulic consumer.

[0018] At least one advantage over the prior art is provided by the movable valve member being moveable from (i) a neutral closed position to (ii) a first position opening a flow path between the first consumer port and the inlet port channel, and between the second consumer port and the second tank channel; and (iii) a second position opening a flow path between the second consumer port and the inlet port channel, and between the first consumer port and the first tank channel. [0019] At least one advantage over the prior art is provided by the inlet section comprising the first tank channel and the second tank channel, and the first tank channel and the second tank channel being joined in the inlet section.

[0020] At least one advantage over the prior art is provided by the first tank channel and the second tank channel being hydraulically connected to the at least one tank port in the inlet section.

[0021] At least one advantage over the prior art is provided by the end section comprising the first tank channel and the second tank channel, and the first tank channel and the second tank channel being joined in the end section.

[0022] At least one advantage over the prior art is provided by the first tank channel and the second tank channel being hydraulically connected to the tank port in the end section.

[0023] At least one advantage over the prior art is provided by the end section comprising an inlet port channel stop.

[0024] An inlet port channel stop may for example be a channel of a given length that is terminated in a dead end, such that no fluid may pass therethrough.

[0025] At least one advantage over the prior art is provided by the end section and/or the inlet section comprising a tank channel stop for the first tank channel and/or the second tank channel.

[0026] At least one advantage over the prior art is provided by a control section for controlling a hydraulic consumer having at least one consumer port, the control section comprising: an inlet port channel; a first tank channel; a second tank channel; a moveable valve member for controlling a flow of hydraulic fluid, wherein said movable valve member is moveable from (i) a neutral closed position to (ii) a first position opening a flow path between the consumer port and the inlet port channel; and (iii) a second position opening a flow path between the consumer port and the first tank channel or the second tank channel; and a cross channel passageway fluidly connecting the first tank channel and the second tank channel to each other.

[0027] At least one advantage over the prior art is provided by the cross channel passageway being arranged such that it balances a return flow from the hydraulic consumer between the first tank channel and the second tank channel.

[0028] At least one advantage over the prior art is provided by the first tank channel and the second tank channel being open on both sides for connection to an inlet section, an end section, and/or another control section.

[0029] Generally, all terms used in the description are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the [element, device, component, means, step, etc.]” are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] These and other features and advantages of the present disclosure will now be further clarified and described in more detail, with reference to the appended drawings showing different embodiments of a directional control valve system and a control section according to the present disclosure.

[0031] Embodiments of this disclosure will now be described in further detail with reference to the accompanying drawings, in which: [0032] FIG. 1 is a schematic view of a prior art hydraulic circuit design;

[0033] FIG. 2 is a schematic view of a directional control valve system according to a first embodiment of the present disclosure, in which the tank channels are joined inside of each control section;

[0034] FIG. 3 is a schematic view of a directional control valve system according to a second embodiment of the present disclosure;

[0035] FIG. 4 is a perspective view of a directional control valve system according to an embodiment of the present disclosure; and

[0036] FIG. 5 is a schematic view of a control section of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0037] In the following detailed description, some embodiments of the present disclosure will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present disclosure, it will be apparent to one skilled in the art that the present disclosure may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present disclosure.

[0038] Figure 1 is a schematic view of a prior art hydraulic circuit design. The directional control valve system 1 shown herein comprises an inlet section 2 and a bank of three control sections 3 attached to each other in a side to side fashion. The directional control valve system 1 further comprises an end section 4 connected to the last of the three control sections 3. The end section 4 comprises an inlet port channel stop 41 , which acts as a stop and ends the inlet port channel 31 of the control sections 3. The end section further comprises two tank channel stops 47, acting as stops and ending a respective one of the two tank channels 32, 33 of the preceding control section 3.

[0039] The inlet section 2 has an inlet port P for connection to a pump or hydraulic motor and an inlet port channel 21 connected thereto. The inlet section 1 further comprises a tank port T for connection to a tank. The illustrated inlet section 2 has a single tank port T which is hydraulically connected to and divided into a first and a second tank channel 22, 23 inside the inlet section 2.

[0040] The control sections 3 illustrated herein comprises an inlet port channel 31 arranged in hydraulic connection with the inlet port P of the inlet section 2. The control section further comprises a first tank channel 32 and a second tank channel 33 that are connected to the first tank channel 22 and the second tank channel 23 of the inlet section 2, such that they are in hydraulic connection with the tank port T. The control section 3 further comprises a moveable valve member 34 arranged to control a flow of hydraulic fluid between the inlet port channel 31 , the first and the second tank channel 32, 33, and a first and a second consumer port A, B of a hydraulic consumer 5 connected to the control section 3. The two tank channels 32, 33 continue through each one of the three control sections 3, such that they are all in hydraulic connection with the tank port T.

[0041] When activating the movable valve member 34 in the control section 3, the return flow of hydraulic fluid from the hydraulic consumer 5 connected thereto will, depending on activation direction, be directed to either the first consumer port A or to the second consumer port B. Figure 1 illustrates three identical control sections 3, the only difference therebetween being the position of the movable valve member 34. [0042] In the leftmost control section 3, the movable valve member 34 is in a neutral closed position, in which the hydraulic connection between the two consumer ports A, B of the hydraulic consumer 5 on one side and the inlet port P and the tank port T of the inlet section 2 on the other side is cut off. As such, there is no flow of hydraulic fluid through the movable valve member 34 of the leftmost control section 3.

[0043] In the middle control section 3, the movable valve member 34 is in a first position. Here, the movable valve member 34 opens a hydraulic connection between the first consumer port A and the inlet port P of the inlet section 2, and between the second consumer port B and the second tank channel 33. This means that the hydraulic consumer 5, illustrated herein as a linear actuator, retracts and the return flow flows through the second consumer port B, through the movable valve member 34 wherein it is directed to the second tank channel 33, and then out through the tank port T and onwards to the tank. The entire return flow from this hydraulic consumer 5 is led through the second tank channel 33.

[0044] In the rightmost control section 3, the movable valve member 34 is in a second position. Here, the movable valve member 34 opens a hydraulic connection between the second consumer port B and the inlet port P of the inlet section 2, and between the first consumer port A and the first tank channel 32. This means that the hydraulic consumer 5 extends and the return flow flows through the first consumer port A, through the movable valve member 34 wherein it is directed to the first tank channel 32, and then out through the tank port T and onwards to the tank. The entire return flow from this hydraulic consumer 5 is led through the first tank channel 32.

[0045] One problem with the prior art hydraulic circuit design is that when the return flow is high, either due to certain individual hydraulic consumers 5 in the bank of control sections 3 having a high return flow, or due to several control sections 3 all directing their return flows to the same tank channel 32, 33, there may be an unwanted pressure loss in the return channel 32, 33 experiencing the high return flow.

[0046] Referring now to Figure 2, which shows a schematic view of a directional control valve system 1 according to a first embodiment of the present disclosure. Here, the first and the second tank channel 32, 33 are joined by a cross channel passageway 35 inside of each control section 3. Thus, the return flow of hydraulic fluid from the hydraulic consumers 5 is distributed to both tank channels 32, 33. This results in that a portion of the return flow in the tank channel 32, 33 currently experiencing the highest return flow may be redirected to the other tank channel 32, 33, resulting in a lower pressure drop and energy loss therein.

[0047] Alternatively, the present disclosure may be realized by having a cross channel passageway 35 between the two tank channels 32, 33 only in some of the control sections 3 in the directional control system 1 , e.g. those with high return flows.

[0048] The cross channel passageway 35 illustrated in Figure 2 is located adjacent to the points at which the movable valve member 34 is connected to the first and second tank channels 32, 33. In an alternative embodiment, the cross channel passageway is located between the points at which the movable valve member 34 is connected to the first and second tank channels 32, 33.

[0049] Figure 3 illustrates a schematic view of a directional control valve system 1 according to a second embodiment of the present disclosure. Here, the inlet section 2 comprises two tank ports T for connection of the inlet section 2 to one or more tanks. Each tank port T is connected to a respective tank channel 22, 23 in the inlet section 2. These tank channels 22, 23 are then connected to the first and second tank channel 32, 33 of the neighbouring control section 3. Like in the first embodiment, the inlet section 2 comprises an inlet port P for connection to a pump or hydraulic motor. [0050] The control section 3 of the second embodiment comprises a moveable valve member 34 arranged to control a flow of hydraulic fluid between the inlet port channel 31 , the first and the second tank channel 32, 33, and a consumer port A of a hydraulic consumer 5 connected to the control section 3. The two tank channels 32, 33 continue through each one of the three control sections 3, such that they are all in hydraulic connection with the two tank ports T.

[0051] Figure 3 illustrates three identical control sections 3, the only difference therebetween being the position of the movable valve member 34. The movable valve member 34 is movable between a neutral position, a first position, and a second position.

[0052] In the first position, shown in the middle control section 3, the movable valve member 34 opens a hydraulic connection between the consumer port A and the tank ports T of the inlet section 2. This means that the hydraulic consumer 5, retracts and the return flow flows through the consumer port A, through the movable valve member 34 wherein it is directed to the second tank channel 33, and then out through the tank ports T and onwards to the tank. The return flow from this hydraulic consumer 5 is led first to the second tank channel 33, after which a portion of the flow is redirected to the first tank channel 32 by means of passage through the cross channel passageway 35. Thus, the return flow is reduced in the second tank channel 33 and the resulting pressure loss is reduced.

[0053] In the second position, shown in the leftmost control section 3, the movable valve member 34 opens a hydraulic connection between the consumer port A and the inlet port P of the inlet section 2. In the neutral position, shown in the rightmost control section 3, the movable valve member 34 cuts off the hydraulic connection between the consumer port A of the hydraulic consumer 5 on one side and the inlet port P and the two tank ports T of the inlet section 2 the other side. As such, there is no flow of hydraulic fluid through the movable valve member 34 of the rightmost control section 3.

[0054] The directional control valve system 1 of the second embodiment further comprises an end section 4 connected to the last of the three control sections 3. The end section 4 comprises an inlet port channel stop 41 , which acts as a stop and ends the inlet port channel 31 of the control sections 3. The end section further comprises a tank channel bridge 43, joining the two tank channels 32, 33 of the preceding control section 3. As such, the flow of hydraulic fluid may be balanced between the two tank channels 32, 33 also by passage through the tank channel bridge 43 of end section 4.

[0055] Figure 4 is a perspective view of a directional control valve system 1 according to an embodiment of the present disclosure. The illustrated embodiment comprises an inlet section 2, two control sections 3, and an end section 4. Each one of the two control sections 3 comprises a cross channel passageway 35 connecting the two tank channels 32, 33 thereof. Here, the cross channel passageway 35 is seen to be integrally formed with the control section 3, and closed to all but the first and second tank channel 32, 33, such that it may better balance the flow rate therebetween. This means that, once the directional control valve system 1 is assembled, there is no hydraulic connection between the cross channel passageway 35 and other parts of the directional control valve system its part of than the first and second tank channel 32, 33.

[0056] Figure 5 is a schematic view of a control section 3 of the present disclosure. The control sections 3 illustrated herein comprises an inlet port channel 31 arranged to be hydraulically connected to a pump or a hydraulic motor, e.g. via an inlet port P of an inlet section 2. The control section 3 further comprises a first tank channel 32 and a second tank channel 33 that arranged to be hydraulically connected to a tank, e.g. via a tank port T of an inlet section 2. The first and the second tank channel 32, 33 are joined and hydraulically connected by a cross channel passageway 35. The control section 3 further comprises a moveable valve member 34 arranged to control a flow of hydraulic fluid between the inlet port channel 31, the first and the second tank channel 32, 33, and consumer ports A, B of a hydraulic consumer 5 that is to be connected to the control section 3. The inlet channel 31 and the two tank channels 32, 33 continue through the control section 3, such that a plurality of control sections 3 may be connected to each other in series, thus forming a bank of control sections 3 that are all in hydraulic connection with one another.

[0057] By having a cross channel passageway 35 connect the two tank channels 32, 33 of the control section 3, the return flow of hydraulic fluid from a hydraulic consumers 5 connected thereto may be distributed to both tank channels 32, 33. This results in that a portion of the return flow in the tank channel 32, 33 currently experiencing the highest return flow may be redirected to the other tank channel 32, 33, resulting in a lower pressure drop and energy loss therein.

[0058] The person skilled in the art realizes that the present disclosure by no means is limited to the embodiments described above. The features of the described embodiments may be combined in different ways, and many modifications and variations are possible within the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word "comprising" does not exclude the presence of other elements or steps than those listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.