Field of the invention

The present invention generally relates to the field of valves for controlling supply of grease.

Background of the invention Lubrication systems are used in various machines and vehicles to supply lubrication to moving mechanical parts. Such lubrication systems normally comprise electrically controlled valves for controlling supply of lubricant towards the points where lubrication is desired (also referred to as lubrication points). Grease is commonly used as lubricant in such lubrication systems. When grease is accumulated in dead spaces of the lubrication system (i.e. spaces without a constant flow of grease) and subjected to high pressures, it tends to separate into its two basic components: oil and soap. Such dead spaces may be present e.g. in the valves for controlling the supply of lubricant, and soap from separated grease may clog the valve, thereby interfering, or even interrupting, the operation of the valve.

US6260664 shows a lubrication valve comprising vents for preventing accumulation of grease residue in the valve, which grease residue may interfere with the closing of the valve. A drawback with such a lubrication valve is that one or more additional venting bodies (or parts) comprising the vents has to be mounted to the existing valve, thereby increasing the number of additional components required in the lubrication valve. Further, such a lubrication valve requires an arrangement for gathering drained grease from the vents, which renders the implementation even more difficult. Summary of the invention

Thus, there is a need for providing alternatives and/or new devices that would overcome, or at least alleviate or mitigate, at least some of the above mentioned drawbacks. It is with respect to the above considerations that the present invention has been made. An object of the present invention is to provide an improved alternative to the above mentioned technique and prior art. More specifically, it is an object of the present invention to provide a valve for controlling supply of grease with a reduced risk of operation failure. These and other objects of the present invention are achieved by means of a valve having the features defined in the independent claim. Preferable embodiments of the invention are characterized by the dependent claims.

Hence, according to an aspect of the present invention, a valve for controlling supply of grease is provided. The valve comprises a housing, in which a chamber is defined, and a closing member movably arranged within the chamber between an open position, in which a main flow of grease is admitted, and a closed position, in which the main flow of grease is blocked. A gap is defined between the circumference of the closing member and an inner wall of the chamber for admitting a flow of grease when the closing member moves between the closed and open positions. Further, at least one passage extends through the closing member and/or in the housing for admitting a flow of grease between opposite sides of the closing member when the closing member moves between the closed and open positions. The valve is adapted such that a flow of grease occurs in the gap when the closing member moves towards one of the closed and open positions, which flow is larger than a flow of grease in the gap occurring when the closing member moves towards the other one of the closed and open positions.

Movement of the closing member (which also may be referred to as a sealing member or closing body) in the chamber causes movement of grease in the chamber. When the closing member moves between the closed and open positions, a flow of grease is induced (or created) in the gap and/or in the passage in a direction opposite to the direction of movement of the closing member, as grease is displaced in front of the moving closing member.

The present invention uses the concept of creating a circulation of grease in the chamber for reducing accumulation of grease in dead spaces. The valve is adapted such that the flow of grease in the gap created when the closing member moves in one direction (i.e. towards one of the closed and open positions) is larger than the flow of grease in the gap occurring when the closing member moves in the opposite direction (i.e. towards the other one of the closed and open positions), which flow even may be zero. For example, the valve may comprise means for reducing (alternatively increasing) the flow of grease in the gap in a first flow direction compared to a flow of grease in the gap in a second direction opposite to the first direction. Hence, the flow of grease in the gap is larger in one direction compared to the opposite direction, which in the following may be referred to as an asymmetric flow. The asymmetric flow in the gap may further create a corresponding

asymmetric flow in the passage. A larger flow in the gap in one direction (such as from one side to an opposite side of the closing member) may imply a correspondingly smaller flow in the passage in the same direction (i.e. from said one side to the opposite side of the closing member). As the size of the flow in the gap, and consequently also in the passage, is direction dependent, circulation of grease in the chamber is facilitated. The grease is forced to circulate through the gap and then through the passage in a certain

circulation direction, instead of merely reciprocating back and forth in the gap and/or the passage. Hence, a repeated movement of the closing member causes the grease to circulate in the chamber (and the passage).

The circulation of grease reduces dead space in the valve, where grease may be accumulated and subjected to high pressure. This reduces the risk of grease separating into oil and soap, which in turn reduces the risk of soap clogging the valve possibly causing operation failure. Further, the present invention is advantageous in that additional venting parts (as used in prior art) for draining accumulated grease from the chamber may not be required. The passage (which also may be referred to as a channel) may be arranged to fluidly connect (i.e. allow a flow of grease between) portions (or

compartments) of the chamber located at opposite sides of the closing member, and may thus be defined in the closing member and/or in the housing.

It will be appreciated that the main flow of grease may be a flow of grease towards a lubrication point (e.g. in a lubrication system), which main flow is controlled by the valve according to the present invention.

In the following, several embodiments will be described for facilitating the above described asymmetric flow in the gap.

According to an embodiment of the present invention, the gap may be at least partially tapered, thereby facilitating flow of grease in the gap in the tapering direction (i.e. the direction in which the gap gets narrower). The tapered shape of the gap may further inhibit flow of grease in the direction opposite to the tapering direction. Hence, the flow of grease in the gap in the tapering direction created when the closing member moves towards one of the closed and open positions is larger (as it is facilitated) compared to the flow of grease in the gap in the direction opposite to the tapering direction created when the closing member moves towards the other one of the closed and open positions.

In the present specification, the term "tapered" is to be widely interpreted and may not just include a continuous narrowing conical shape, but any shape being gradually (or stepwise) narrower in a certain direction.

In an embodiment, the closing member may have an at least partially tapered shape in order to define a tapered gap between the closing member and the inner wall of the chamber. The present embodiment is advantageous in that manufacturing of the valve is facilitated, as the closing member with an at least partially tapered shape may be used together with a housing having a standard cylindrical chamber. Alternatively, or as a complement, at least a portion of the chamber may be tapered in order to define the tapered gap. An alternative (or complementing) way of influencing the flow in the gap is to influence the flow of grease in the passage. In a particular direction of movement of the closing member, a smaller flow in the passage implies a larger flow in the gap, as a constant amount of grease is displaced by the closing member. When the flow of grease is inhibited in the passage, a larger flow is forced through the gap. Hence, the size of the flow in the passage may be direction dependent (asymmetric), thereby also making the flow in the gap direction dependent.

For example, the passage (in the closing member and/or in the housing) may be at least partially tapered, thereby facilitating flow of grease in the passage in the tapering direction (i.e. the direction in which the passage gets narrower). The tapered shape of the passage may further inhibit flow of grease in the direction opposite to the tapering direction.

According to another example, a check valve may be arranged in the passage so as to inhibit flow of grease in one direction in the passage.

Several passages may be defined in the closing member and/or in the housing, wherein merely one may be provided with a check valve for admitting a total flow of grease in the passages being larger in one direction compared to the opposite direction. According to an embodiment of the present invention, an edge may be arranged at the inner wall of the chamber, the edge being adapted to inhibit flow of grease in the gap when the closing member moves towards said other one of the closed and open positions (i.e. in the movement direction of the closing member wherein the flow of grease is reduced in the gap). The edge may be adapted to remove (or scrape off) grease from the closing member in one of the movement directions of the closing member.

In an embodiment of the present invention, the circumference of the closing member and an inner wall of the chamber may be shaped such that the inner wall of the chamber is adapted to guide the closing member towards the closed position. Hence, the size and shape of the gap may be adapted so as to admit a flow of grease in at least one direction while still allowing a guided movement of the closing member towards (and preferably also away from) the closed position.

According to an embodiment of the present invention, a first compartment (or space) of the chamber may be defined between a first end of the closing member and the inner wall of the chamber and a second compartment (or space) of the chamber may be defined between a second end of the closing member (e.g. opposite to the first end) and the inner wall of the chamber. Further, an inlet for the main flow of grease to the second compartment of the chamber and an outlet for the main flow of grease from the second

compartment of the chamber are defined in the housing. In other words, the closing member divides the chamber into two compartments. The closing member may thus close the main flow of grease by closing the inlet to and/or outlet from the second compartment.

In an embodiment, the gap and the passage may be adapted to admit flow of grease between the first and second compartments when the closing member moves between the closed and open positions. Hence, when the closing member moves towards the closed position, grease flows through the gap and/or the passage to the first compartment, and when the closing member moves towards the open position, grease flows through the gap and/or the passage to the second compartment, whereby grease is moved (or displaced) between the first and second compartments. Due to the asymmetrical flow in the gap, grease will be forced to circulate through the gap, the first

compartment, the passage and the second compartment (or in the reversed order), as the closing member moves back and forth. According to an embodiment of the present invention, a lubrication system is provided. The lubrication system comprises a valve as defined in any one of the preceding embodiments.

Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following.

Brief description of the drawings

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, in which:

Figures 1 a and 1 b show a valve according to an embodiment of the present invention; Figures 2a and 2b show a valve according to another embodiment of the present invention;

Figures 3a and 3b show a valve according to yet another embodiment of the present invention; and

Figure 4 shows a valve according to yet another embodiment of the present invention.

All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested.

Detailed description of embodiments With reference to Figures 1 a to 3b, three valves for controlling supply of grease according to different embodiments of the present invention will be described. Each valve has a closing member and Figure 1 a, 2a and 3a illustrate when the closing member moves towards a closed position and Figure 1 b, 2b and 3b illustrate when the closing member moves towards an open position.

In order to clearly illustrate the function of each valve, the illustrations are simplified and may not be according to scale, e.g. some dimensions may be exaggerated in order to illustrate certain features. A valve 1 according to a first embodiment of the present invention will be described with reference to Figures 1 a and 1 b.

The valve 1 comprises a housing 100, in which a chamber 105 is defined. The closing member 130 is movably arranged within the chamber 105 and divides the chamber 105 into a first compartment 1 10, defined between a first end 131 of the closing member 130 and an inner wall of the chamber 105, and a second compartment 120 defined between a second end 132 of the closing member 130 and an inner wall of the chamber 105. The second compartment 120 has an inlet 121 and an outlet 122 for admitting a main flow of grease to enter and exit the second compartment 120, respectively.

The closing member 130 is arranged to reciprocate between an open position, in which the main flow of grease is admitted through the inlet 121 and outlet 122 of the second compartment 120, and a closed position, in which the main flow of grease is blocked. For example, the closing member 130 may be adapted to seal (or block) the outlet 122 in order to block the main flow of grease. When the closing member 130 is in the open position, the main flow of grease is admitted towards a lubrication point. The outlet 122 may also be referred to as the valve seat.

A gap 140 is defined between the circumference of the closing member 130 and an inner wall of the chamber 105 for admitting a flow of grease between the first and second compartments 1 10, 120 (i.e. between opposite sides of the closing member 130). The gap 140 may partially or entirely surround the closing member 130. Further, at least one passage 135 is defined in the closing member 130 extending between the first and second compartments 1 10, 120 for admitting a flow of grease there between (i.e. between opposite sides of the closing member 130). The passage may alternatively (or as a complement) be arranged in the housing for admitting a flow of grease between the first and second compartments (not shown). Hence, the passage may extend in the housing from the first compartment to the second compartment. When the closing member 130 moves in the chamber 105, grease is displaced, and a flow of grease is created in the chamber 105. The valve 1 is adapted such that a flow (indicated by arrows 162 in Figure 1 a) of grease occurs in the gap 140 when the closing member 130 moves towards one of the closed and open positions, which flow is larger than a flow (indicated by arrows 165 in Figure 1 b) of grease in the gap 140 occurring when the closing member 130 moves towards the other one of the closed and open positions. Hence, the flow of grease in the gap 140 is larger in one direction compared to the opposite direction, which may be referred to as an asymmetric flow. The asymmetric flow may be obtained by facilitating flow of grease in the gap 140 or in the passage 135 in one direction compared to the opposite direction.

In the present embodiment, the asymmetric flow is obtained by the gap entrance from the second compartment 120 being wider than the gap entrance from the first compartment 1 10, whereby the flow of grease

(indicated by arrows 162 in Figure 1 a) in the gap 140 created when the closing member 130 moves towards the closed position (i.e. the flow in direction from the second compartment 120 to the first compartment 1 10) is facilitated and the flow of grease (indicated by arrows 165 in Figure 1 a) in the gap 140 created when the closing member 130 moves towards the open position (i.e. the flow in direction from the first compartment 1 10 to the second compartment 120) is inhibited (or restrained). As the total flow of grease between the first and second compartments is the same for both movement directions of the closing member 130, the flow of grease in the passage 135 is consequently larger when the closing member 130 moves towards the open position compared to when the closing member 130 moves towards the closed position (as indicated by arrow 164 and arrow 161 , respectively, in Figures 1 a and 1 b).

For example, the gap 140 may have a tapered section 136, which is tapered (i.e. gets narrower) in direction from the second compartment 120 towards the first compartment 1 10. In order to obtain the tapered section 136 of the gap 140, the closing member 130 may be at least partially tapered towards the second end 131 . Alternatively (or as a complement), the inner walls of the chamber may be inclined in order to define a tapered gap between the circumference of the closing member and the chamber (not shown).

Preferably, the tapered section 136 of the gap 140 may be continuously tapered, such as conically tapered.

A valve 2 according to a second embodiment of the present invention will be described with reference to Figures 2a and 2b. The valve 2 may be equally configured as the valve described with reference to Figures 1 a and 1 b, except that the asymmetric flow is obtained by the passage entrance from the first compartment 210 being wider than the passage entrance from the second compartment 220, whereby flow of grease is facilitated in the passage 235 from the first compartment 210 to the second compartment 220 and inhibited (or restrained) in the opposite direction. For example, the passage 235 may be at least partially tapered (i.e. get narrower) in direction from the first compartment 210 towards the second compartment 220.

When the closing member 230 moves towards the open position, the flow of grease (indicated by arrow 264 in Figure 2b) in the passage 235 is larger compared to the flow of grease (indicated by arrow 261 in Figure 2a) induced when the closing member 230 moves towards the closed position due to the tapered shape of the passage 235. As previously described, in a particular direction of movement of the closing member 230, a smaller flow in the passage 235 implies a larger flow in the gap 240, as a constant amount of grease is to be displaced by the closing member 230. Hence, when the closing member 230 moves towards the open position, the flow of grease (indicated by arrows 265 in Figure 2b) in the gap 240 is smaller compared to the flow of grease induced when the closing member 230 moves towards the closed position (which flow is indicated by arrows 262 in Figure 2a).

A valve 3 according to a third embodiment of the present invention will be described with reference to Figures 3a and 3b. The valve 3 may be equally configured as the valve described with reference to Figures 1 a and 1 b, except that the asymmetric flow is obtained by having a check valve 338 arranged in the passage 336. In the present embodiment, several passages 336, 337 are defined in the closing member 330 connecting the first and second

compartments 310, 320. The check valve 338 is arranged in one of the passages 336 in order to facilitate flow of grease in that passage 336 from the first compartment 310 to the second compartment 320 and inhibit flow of grease in the opposite direction. Alternatively, a single passage may be defined in the closing member, wherein a check valve may be arranged in that passage (not shown).

In similarity with the previously described embodiment (described with reference to Figures 2a and 2b), the flow in the gap 340 is influenced by influencing the flow of grease in the passages 336, 337. When the closing member 330 moves towards the open position, the flow of grease (indicated by arrows 366, 367 in Figure 3b) in the passages 336, 337 is larger compared to the flow of grease (indicated by arrow 361 in Figure 3a) induced in the passages 336, 337 when the closing member 330 moves towards the closed position, as the check valve 338 opens up by the flow of grease in direction from the first compartment 310 to the second compartment 320 and closes by the flow of grease in the opposite direction. Consequently, when the closing member 330 moves towards the open position, the flow of grease (indicated by arrows 365 in Figure 3b) in the gap 340 is smaller compared to the flow of grease (indicated by arrows 362 in Figure 3a) induced when the closing member 330 moves towards the closed position.

In the above described embodiments, the flow of grease in the gap is larger in direction from the second compartment to the first compartment (which is induced when the closing member moves towards the closed position) compared to the opposite direction (which is induced when the closing member moves towards the open position) in order to create a circulation of grease in the chamber. Hence, a net flow of grease is forced to circulate from the second compartment through the gap to the first compartment and then through the passage back to the second compartment. However, it will be appreciated that the valve alternatively may be arranged such that the flow of grease in the gap is larger in direction from the first compartment to the second compartment compared to the opposite direction. The net flow of grease then circulates in the opposite direction, i.e. from the second compartment through the passage to the first compartment and then through the gap back to the second compartment. The means for inducing the circulation (the tapered gap, the tapered passage and the check valve in the passage) may then be reversely arranged (i.e. being tapered in the opposite direction or having the check valve arranged to inhibit flow in the opposite direction compared to what is described above with reference to Figures 1 a to 3b).

With reference to Figure 4, a valve 4 according to an embodiment of the present invention will be described. The valve 4 may be similarly configured as the valve described with reference to Figures 1 a and 1 b.

The valve 4 comprises a housing (or valve body) 400 adapted to be installed in a lubrication system for controlling a main flow of grease from a lubrication source towards a lubrication point in a machinery. The housing 400

comprises a chamber 405, in which a closing member 430 adapted to admit or block the main flow of grease is arranged. In the present embodiment, the valve 4 is an electrically controlled solenoid valve having a magnet core 402 for controlling the valve 4. The magnet core 402 may be arranged to enclose the closing member 430 in the chamber 405. Further, an isolation ring 401 made of non-magnetic material may be arranged to concentrate magnet flow in the gap between the magnet core 402 and the closing body 430. The isolation ring 402 reduces the risk of short-cutting magnet flow from the magnet core to the housing 400.

The closing member 430 is fitted within the chamber 405 and is movable between a closed position and an open position. Preferably, the closing member 430 is a cylindrical piston and the chamber 405 has a corresponding cylindrical shape, wherein the closing member 430 may reciprocate in the chamber 405.

The closing member 430 divides the chamber 405 into a first compartment 410 defined by a first end 431 of the closing member 430 and the inner wall of the chamber 405 and a second compartment 420 defined by a second end 432 of the closing member 430 and the inner wall of the chamber 405. The main flow of grease enters the second compartment 420 via an inlet 421 and exits the second compartment 420 via an outlet 422. The closing member 430 comprises a protruding portion 434 disposed at the second end 432 of the closing member 430 for blocking (or sealing) the outlet 422, thereby blocking the main flow of grease.

A spring 403 (or any other resilient means) is arranged to force the closing member 430 towards the closed position. The spring 403 may e.g. be arranged between the magnet core 402 and the closing member 430. When the magnet core 402 is activated, the force of the spring 403 is counteracted and the closing member 430 is pulled towards the magnet core 402, whereby the protruding portion 434 is removed from the outlet 422 and the closing member 430 is positioned in its open position. When the magnet core 402 is deactivated, the closing member 430 is pushed back to the closed position by the spring 403.

The diameter (or cross section) of the closing member 430 is slightly smaller than the diameter (or cross section) of the chamber 405, whereby a narrow gap 440 is defined between the circumference of the closing member 430 and the inner wall of the chamber 405 for admitting a flow of grease there between. The gap 440 may entirely or partially surround the closing member 430. For example, the gap 440 may be confined to a (narrow) channel between the closing member 430 and the inner wall of the chamber 405 and the remaining circumference of the closing member 430 may be arranged in (close) abutment to the inner wall of the chamber 405. However, it is advantageous to have the gap 440 (at least almost) entirely surrounding the closing member 430, as grease then is allowed to flow around the entire closing member 430.

Further, the width of the gap 440 may preferably be adapted such that a flow of grease is admitted in the gap 440 while the inner walls of the chamber 405 still guides the closing member 430 in its movement between the closed and open positions. In the present embodiment, the gap 440 may not be visible in Figure 4, as it is rather narrow. However, the gap 440 is still wide enough to admit a flow of grease between the closing member 430 and the inner wall of the chamber 405. Further, the closing member 430 has a tapered section 436, whereby the gap 440 is partially tapered. The tapered portion of the gap 440 gets narrower in direction from the second compartment 420 to the first compartment 430. For example, the narrowest portion of the gap 440 may have a width in the order of 0.1 mm.

An edge 470 is arranged in the gap 440 at the inner wall of the chamber 405. The edge 470 provides a sharp transition between a wider cross section to a narrower cross section of the chamber 405 (in direction from the first compartment 410 towards the second compartment 420).

The closing member 430 further comprise a passage 435 extending from the first end 431 of the closing member 430 to the second end 432 of the closing member 430, thereby fluidly connecting the first and second compartments 410, 420. Optionally, the spring 403 may be supported, and partially arranged, within the passage 435. For example, the narrowest portion of the passage 435 may have a diameter of around 2 mm.

In the following, operation of the valve 4 will be described. When the closing member 430 moves towards its closed position (i.e. downwards in Figure 4) grease is displaced in the chamber 405 and a flow of grease is induced in the gap 440 in the tapering direction of the gap 440, from the second

compartment 420 to the first compartment 410. As the gap 440 is wider at its entrance from the second chamber 420, flow of grease in direction from the second compartment 420 to the first compartment 410 is facilitated. In addition, a flow of grease is induced in the passage 435 from the second compartment 420 to the first compartment 410. Accordingly, grease is transferred from the second compartment 420 to the first compartment 410 through the gap 440 and the passage 435.

When the closing member 430 moves towards its open position (i.e. upwards in Figure 4) grease is again displaced in the chamber 405. However, as the gap 440 is narrower at its entrance from the first compartment 410 due to the tapered shape of the gap 440, in particular at the edge 470 at the inner wall of the chamber 405, flow of grease from the first compartment 410 to the second compartment 420 in the gap 440 is inhibited (such as completely or partially blocked). The edge 470 removes (or scrapes of) grease from the closing member 430 when it moves towards the closed position. As the same amount of grease is displaced by the closing member 430 when it moves from the closed position to the open position as when it moves from the open position to the closed position, the total flow of grease between the first and second compartments 410, 420 is the same in both directions. However, as the flow in the gap 440 is reduced (inhibited) when the closing member 430 moves towards the open position, the flow of grease induced in the passage 435 from the first compartment 410 to the second compartment 420 is

correspondingly increased.

In conclusion, grease is transported in the gap 440 (i.e. at the circumference of the closing member 430) to the first compartment 410 and then transported through (within) the closing member 430 via the passage 435 back to the second compartment 420. Thus, a circulation of grease is obtained, which reduces dead space in the chamber 405. In particular, accumulation of stagnated grease in the first compartment 410 is reduced, thereby reducing the risk of soap, separated from oil in the grease, to cause mal function of the spring 403.

While specific embodiments have been described, the skilled person will understand that various modifications and alterations are conceivable within the scope as defined in the appended claims.

For example, the embodiments described above may be combined with each other in order to create further embodiments. For example, a tapered gap may be combined with a check valve in the passage and/or a tapered passage etc.