NL2013166B1 - Pump element, pump and lubrication system. - Google Patents

Abstract

The invention relates to a pump element 100 for use in a lubrication system 200 for dispensing predetermined charges 112 of a liquid lubricant to lubrication points of industrial equipment. The pump element comprises a dosage chamber 107 for forming said predetermined charges and a first outlet 103 that is arranged in liquid communication with said dosage chamber to dispense said predetermined charges. The pump element further comprises a piston 105 having a pressure relief liquid flow path 108 in which a safety relief valve 110 is disposed. In case the predetermined charge of the liquid lubricant cannot flow out of the first outlet, pressure rising in the dosage chamber is limited by opening of the safety relief valve when the pressure in the dosage chamber reaches a predetermined threshold value. The invention also relates to a pump 1 and a lubrication system comprising the proposed pump element.

Description

Pump element, pump and lubrication system

The invention relates to a pump element for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment such as trucks, mining or construction equipment and agricultural machines. The invention also relates to a pump and a lubrication system, in particular a progressive centralized lubrication system, comprising the pump element according to the invention.

Progressive centralized lubrication systems are being used to lubricate industrial equipment by dispensing small, measured amounts of a lubricant over short, frequent time intervals. Known systems generally are quite complex and bulky due to the number and the dimensions of the components used such as a pump for dispensing predetermined charges of a liquid lubricant. In addition, pumps of known systems generally require both electrical power and pressurized air for being operated.

Especially for mobile industrial equipment such as trucks, mining or construction equipment and agricultural machines, the issues mentioned above regarding the lubrication system and the pump respectively, are considerable disadvantages. At least some of these disadvantages have been overcome by a pump that was developed by the applicant. Figure 1 shows a schematic cross-sectional view of this pump that only requires direct current (DC) electrical power to be operated. Nevertheless, there is a need for further improvements in particular regarding size reduction of the pump.

It is an object of the invention to provide a pump element that enables further size reduction of the pump shown in figure 1. In addition, the pump element according to the invention pre-empts or at least reduces at least one of the other disadvantages mentioned above. It is also an object of the invention to provide a pump that comprises a pump element according to this invention. Furthermore, it is an object of the invention to provide a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment comprising a pump according to this invention.

Aspects of this invention are set out in the accompanying independent and dependent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as appropriate and not merely as explicitly set out in the claims.

According to a first aspect of this invention, there is provided a pump element for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment. The pump element comprises a housing that is provided with an inlet that is configured to allow a flow of a liquid lubricant to be proportioned to flow into the pump element, a first outlet that is configured to dispense a predetermined charge of said flow of the liquid lubricant, a first liquid flow path that is arranged between and in liquid communication with the inlet and the first outlet, and a piston and a first one-way passage arrangement that are disposed in said first liquid flow path thereby defining a dosage chamber for forming the predetermined charge of said flow of the liquid lubricant. The piston is movable between a first position in which the piston allows said flow of the liquid lubricant to flow into the dosage chamber and a second position in which the piston is configured to prevent liquid communication between the inlet and the dosage chamber. Upon moving the piston from the first towards the second position said piston prevents liquid communication between the inlet and the dosage chamber and forces said predetermined charge of the liquid lubricant out of the dosage chamber into the first outlet via the first one-way passage arrangement that is configured to prevent said predetermined charge of the liquid lubricant to flow back from the first outlet into the dosage chamber. The piston comprises a second liquid flow path that is arranged between and in liquid communication with said dosage chamber and a second outlet that is configured to allow said predetermined charge of the liquid lubricant to flow from said dosage chamber out of the pump element, and a second one-way passage arrangement that is disposed in said second liquid flow path, the second one-way passage arrangement being configured to allow liquid communication between said dosage chamber and the second outlet when a pressure in said dosage chamber reaches a predetermined threshold value.

In an embodiment of the pump element according to this invention, the second one-way passage arrangement is a safety relief valve.

In an embodiment of the pump element according to this invention, the predetermined threshold value is 275 ± 10% bar.

In an embodiment of the pump element according to this invention, the first oneway passage arrangement is a check valve.

In an embodiment of the pump element according to this invention, the first and second liquid flow paths comprise at least one of bores and ducts.

In an embodiment of the pump element according to this invention, the dosage chamber has a predetermined volume in a range of 0.1 to 0.3 cm3.

According to a second aspect of this invention, there is provided a pump for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment, the pump comprising a pump element according to this invention.

In an embodiment of the pump according to this invention, the pump further comprises a cam arrangement that is arranged to engage with the piston of the pump element and to drive said piston between said first and second positions.

In an embodiment of the pump according to this invention, the pump further comprises a storage unit comprising the liquid lubricant to be proportioned, a first liquid communication element that is disposed between the inlet of the pump element and the storage unit and arranged to establish liquid communication between said inlet and storage unit, and a second liquid communication element that is disposed between the second outlet of the pump element and the storage unit and arranged to establish liquid communication between said second outlet and storage unit.

In an embodiment of the pump according to this invention, the first and second liquid communication elements comprise ducts.

In an embodiment of the pump according to this invention, the pump is operable by direct current, DC, electrical power.

According to a third aspect of this invention, there is provided a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment comprising a pump according to this invention.

In an embodiment of the lubrication system according to this invention, the lubrication system is a progressive centralized lubrication system.

In an embodiment of the lubrication system according to this invention, the lubrication system further comprises a third liquid communication duct and a first progressive block, the third liquid communication duct being disposed between the first outlet of the pump element and the first progressive block and arranged to establish liquid communication between said first outlet and first progressive block.

In an embodiment of the lubrication system according to this invention, the third liquid communication element comprises a duct.

Embodiments of the present invention will be described hereinafter, by way of example only, with reference to the accompanying drawings which are schematic in nature and therefore not necessarily drawn to scale. Furthermore, like reference signs in the drawings relate to like elements. On the attached drawing sheets, • figure 1 shows a schematic cross-sectional view of an exemplary embodiment of a pump that was developed by the applicant for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment. Although this pump already solved problems associated with conventional pumps comprised in the state of the art, further improvement was required; • figure 2a shows a schematic cross-section of a first embodiment of a pump element according to the invention. The pump element is shown when in use in a pump for dispensing a predetermined charge of a liquid lubricant. A piston of the pump element is in a first position during a pump cycle, thereby allowing a flow of the liquid lubricant to flow into a dosage chamber of the pump element; • figure 2b shows a schematic cross-section of the first embodiment of the pump element wherein the piston is being moved from the first position towards a second position during the pump cycle, thereby forcing the predetermined charge of the liquid lubricant out of the dosage chamber towards a first outlet of the pump element; • figure 2c shows a schematic cross-section of the first embodiment of the pump element wherein the piston is in the second position during the pump cycle. The dosage chamber is empty and the piston will be moved back towards the first position in which a next flow of the liquid lubricant can flow into the dosage chamber; • figure 2d shows a schematic cross-section of the first embodiment of the pump element when in use in the pump for dispensing a predetermined charge of a liquid lubricant. The piston is being moved from the first towards the second position. The predetermined charge of the liquid lubricant is prevented from flowing out of the dosage chamber towards the first outlet because a first one-way passage arrangement that is arranged between the dosage chamber and the first outlet cannot be opened as the pressure at the first outlet is at least equal to the pressure in the dosage chamber; • figure 2e shows a schematic cross-section of the first embodiment of the pump element in a use situation in which the pressure at the first outlet remains and the piston is still being forced towards the second position. When the pressure in the dosage chamber reaches a predetermined threshold value, a second one-way passage arrangement that is arranged in the piston is being opened, thereby allowing the predetermined charge of the liquid lubricant to flow out of the dosage chamber towards a second outlet via a second liquid flow path; • figure 2f shows a schematic cross-section of the first embodiment of the pump element wherein the piston is in the second position and the dosage chamber is empty. Upon moving the piston back into the first position a next flow of the liquid lubricant is allowed to flow into the dosage chamber. This situation was already shown in figure 2a. • figure 3 shows a schematic cross-sectional view of a first embodiment of a pump according to the invention for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment; • figure 4 shows a schematic layout of a first embodiment of a lubrication system according to the invention for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment. The lubrication system comprises the pump according to the invention as shown in figure 3.

Embodiments of the present invention are described in the following with reference to the accompanying drawings.

Figure 1 shows a schematic cross-sectional view of an exemplary embodiment of a pump 1 that was developed by the applicant for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment such as trucks, mining or construction equipment and agricultural machines.

The pump 1 comprises a storage unit 3 for storing the liquid lubricant to be dispensed. The liquid lubricant can be oil or grease. In relation to the present invention, greases having a National Lubricating Grease Institute (NLGI) consistency number in a range of 0 to 4 are of particular interest. The skilled person will appreciate that common greases have a NLGI consistency number in the range of 1 to 3. Greases having a NLGI consistency number of 0, 1 and 2 are typically used in highly loaded gearing, whereas greases having a NLGI consistency number in the range of 1 to 4 are often used in rolling contact bearings.

The pump 1 also comprises a pump element 20 that is in liquid communication with the storage unit 3 for receiving a flow of the liquid lubricant to be dispensed and a motor unit 4 that is configured to drive the pump element 20.

Furthermore, the pump 1 comprises an exhaust arrangement 6 that is configured to enable a predetermined charge of the liquid lubricant to flow from the pump element 20 back into the storage unit 3 in situations in which the predetermined charge of the liquid lubricant cannot flow out of a first outlet 103 of the pump element 20 towards a transport line of the lubrication system that is in liquid communication with the first outlet 103 and is configured to transport the predetermined charge of the liquid lubricant to a lubrication point, e.g. a bearing point. In an exemplary situation in which pressure builds up in the pump element 20 as a result of obstruction of the first outlet 103, activation of the exhaust arrangement 6 can at least limit and preferably prevent damage to at least one of the pump 1 and the pump element 20. Obstruction of the first outlet 103 may be caused by the presence of a pressure at the first outlet 103 that is at least equal to the pressure in the pump element 20 or by clogging of the first outlet 103.

Compared to pumps known from the prior art, the pump 1 has smaller dimensions and only requires direct current (DC) electrical power to be operated. The latter feature is particularly advantageous for application of the pump 1 in lubrication systems in agricultural machines as these machines generally are not equipped with pressurized air.

Although the pump 1 has smaller dimensions than pumps known from the prior art, further improvement regarding size reduction was required. This can be realized by the pump element 100 according to the invention that will be discussed with reference to figures 2a to 2f.

Figure 2a shows a schematic cross-section of a first embodiment of a pump element 100 according to the invention. The pump element 100 is shown when in use in a pump 1 for dispensing a predetermined charge 112 of a liquid lubricant.

The pump element 100 comprises a housing 101 that is provided with an inlet 102 that is configured to allow a flow of the liquid lubricant to be proportioned, e.g. oil or grease, to flow into the pump element 100 via the inlet 102. A first outlet 103 is configured to dispense a predetermined charge 112 of the liquid lubricant that was received in the pump element 100. A first liquid flow path 104 is arranged between and in liquid communication with the inlet 102 and the first outlet 103. In the first embodiment of the pump element 100 shown in figure 2a, the first liquid flow path 104 is implemented as a longitudinal bore in the housing 101. A piston 105 and a first one-way passage arrangement 106 are disposed in the first liquid flow path 104 thereby defining a dosage chamber 107 for forming the predetermined charge 112 of the flow of the liquid lubricant that entered the pump element 100 via the inlet 102.

In the first embodiment of the pump element 100 shown in figure 2a, the oneway passage arrangement 106 is implemented as a check valve comprising a first valve element 120 that is biased by a first compression spring 121 to be in contact with a first seat element 122.

The piston 105 is movable between a first position, as shown in figure 2a, in which the piston 105 allows the flow of the liquid lubricant to enter the dosage chamber 107 via the inlet 102, and a second position, as shown in figure 2c, in which the piston 105 prevents liquid communication between the inlet 102 and the dosage chamber 107. Upon moving the piston 105 from the first towards the second position, the piston 105 prevents liquid communication between the inlet 102 and the dosage chamber 107 while forcing the predetermined charge 112 of the liquid lubricant out of the dosage chamber 107 into the first outlet 103 via the check valve 106 that is configured to prevent the predetermined charge 112 of the liquid lubricant to flow back from the first outlet 103 into the dosage chamber 107.

For the envisaged application of the pump element 100 in lubrication systems 200 for trucks, mining or construction equipment and agricultural machines, the dosage chamber 107 has a predetermined volume in a range of 0.1 to 0.3 cm3. However, the skilled person will appreciate that any suitable predetermined volume can be chosen and put into practice.

As shown in figure 2a, the piston 105 comprises a second liquid flow path 110 that is arranged between and in liquid communication with the dosage chamber 107 and a second outlet 109 that is configured to allow the predetermined charge 112 of the liquid lubricant to flow from the dosage chamber 107 out of the pump element 100, and a second one-way passage arrangement 110 that is disposed in the second liquid flow path 108. In the first embodiment of the pump element 100 shown in figure 2a, the second liquid flow path 108 is implemented as a longitudinal bore in the piston 105.

The second one-way passage arrangement 110 is configured to allow liquid communication between the dosage chamber 107 and the second outlet 109 when a pressure in the dosage chamber 107 reaches a predetermined threshold value. In this way, the pump element 100 is provided with an internal exhaust arrangement for at least limiting and preferably preventing damage to at least one of the pump 1 and the pump element 100 in situations in which the predetermined charge 112 of the liquid lubricant cannot flow out of the first outlet 103 of the pump element 100.

For the envisaged application of the pump element 100 in lubrication systems 200 for trucks, mining or construction equipment and agricultural machines, the predetermined threshold value is 275 ± 10% bar. However, the skilled person will appreciate that any suitable threshold value can be chosen and put into practice by appropriately configuring the second one-way passage arrangement 110 that can be a safety relief valve comprising a second valve element 130 that is biased by a second compression spring 131 to be in contact with a second seat element 132 as is shown in figure 2a.

When the piston 105 is moved from the second position, as shown in figure 2c, into the first position, as shown in figure 2a, the flow of the liquid lubricant to be proportioned is sucked into the dosage chamber 107 via the inlet 102. During this so-called return movement of the piston 105 that is indicated by the arrow in figure 2a, liquid communication between the dosage chamber 107 and the first 103 and second 109 outlets is prevented by the closed check valve 106 and the closed safety relief valve 110, respectively. In the context of this patent application, the first position of the piston 105 as shown in figure 2a is indicated as the first position during a pump cycle.

Figure 2b shows a schematic cross-section of the first embodiment of the pump element 100 wherein the piston 105 is being moved from the first position towards the second position during the pump cycle as is indicated by the arrow. During this so-called pressure rising movement of the piston 105, the pressure in the dosage chamber 107 rises due to the force exerted by the piston 105 on the predetermined charge 112 of the liquid lubricant until the check valve 106 opens against the biasing force exerted by the first compression spring 121 on the first valve element 120.

It is noted that if the pressure in the dosage chamber 107 remains below the predetermined threshold value of 275 ± 10% bar during the pressure rising movement of the piston 105, the safety relief valve 110 remains closed. In that case, liquid communication between the dosage chamber 107 and the second outlet 109 is prevented and the predetermined charge 112 of the liquid lubricant flows out of the dosage chamber 107 into the first outlet 103 via the check valve 106 as is indicated in figure 2b by the two arrows that are drawn at the first outlet 103.

Figure 2c shows a schematic cross-section of the first embodiment of the pump element 100 wherein the piston 105 is in the second position during the pump cycle. The predetermined charge 112 of the liquid lubricant has been pushed out of the dosage chamber 107 into the first outlet 103 via the check valve 106 as is indicated by the two arrows that are drawn at the first outlet 103.

It is illustrated that when the dosage chamber 107 is empty, the piston 105 is in the second position and the check valve 106 and the safety relief valve 110 are closed. Next, the piston 105 will be moved back from the second position towards the first position as is indicated by the arrow in figure 2f. During this movement of the piston 105, which in fact is the return movement of the piston 105 as has been discussed above in relation to figure 2a, a next flow of the liquid lubricant to be dispensed is sucked into the dosage chamber 107 via the inlet 102.

The situations schematically shown in figures 2a to 2c represent one pump cycle under normal operating conditions comprising the return and a pressure rising movements of the piston 105, respectively.

Figure 2d in fact shows the pressure rising movement of the piston 105 as has been discussed above in relation to figure 2b. During the pressure rising movement of the piston 105, the pressure in the dosage chamber 107 rises. However, contrary to the situation that was schematically illustrated in figure 2b, the check valve 106 does not open against the biasing force exerted by the first compression spring 121 on the first valve element 120 because of a pressure at the first outlet 103 that is at least equal to the pressure in the dosage chamber 107 during the pressure rising movement of the piston 105. As a result, the predetermined charge 112 of the liquid lubricant is prevented from flowing out of the dosage chamber 107 towards the first outlet 103.

In order to at least limit and preferably prevent damage to at least one of the pump 1 and the pump element 100, the safety relief valve 110 is configured to open if the pressure in the dosage chamber 107 reaches the predetermined threshold value during the pressure rising movement of the piston 105. As mentioned above, the predetermined threshold value can be any suitable value depending on the envisaged application of the pump element 100. In the particular applications envisaged in relation to the present invention, a predetermined threshold value of 275 ± 10% bar is chosen and put into practice by appropriately configuring the second compression spring 131 that biases the second valve element 130 to be in contact with the second seat element 132.

Figure 2e schematically shows the situation in which the safety relief valve 110 has been opened against the biasing force exerted by the second compression spring 131 on the second valve element 130. As a result, liquid communication between the dosage chamber 107 and the second outlet 109 is established and the predetermined charge 112 of the liquid lubricant can flow out of the dosage chamber 107 into the second outlet 109 via the safety relief valve 110 as is indicated in figure 2e by the two arrows that are drawn in the second outlet 109 of the piston 105.

Figure 2f shows a schematic cross-section of the first embodiment of the pump element 100 wherein the piston 105 is in the second position, the dosage chamber 107 is empty and the check valve 106 and the safety relief valve 110 are closed. Next, the piston 105 will be moved back from the second position towards the first position as is indicated by the arrow in figure 2f. As already discussed above but repeated here for the sake of completeness, a next flow of the liquid lubricant to be dispensed is sucked into the dosage chamber 107 via the inlet 102 during the return movement of the piston 105. This situation is schematically illustrated in figure 2a.

Figure 3 shows a schematic cross-sectional view of a first embodiment of a pump 1 according to the invention for use in a lubrication system for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment. The pump 1 comprises the pump element 100 shown in figures 2a to 2f. By applying the pump element 100 according to the invention, the pump 1 according to the invention as shown in figure 3 has an internal exhaust arrangement instead of the external exhaust arrangement 6 that is provided in the pump 1 as shown in figure 1. As a result, the pump 1 according to the invention as shown in figure 3 has smaller external dimensions than the pump 1 as shown in figure 1.

In addition, the costs of the pump 1 according to the invention can be reduced as the number of components used is reduced by applying the pump element 100 according to the invention. Furthermore, the pump element 100 according to the invention is constructed such that it enables easier assembly and disassembly, i.e. screwing on and off the pump 1. In this way, costs, e.g. maintenance costs, can also be reduced.

Figure 3 further schematically shows that the pump 1 comprises a cam arrangement 140 that is arranged to engage with the piston 105 of the pump element 100 and to drive said piston 105 between the first and second positions described in the foregoing. In this way, no return spring is required for returning the piston 105 from the second to the first position.

The pump 1 according to the invention further comprises a storage unit 3 comprising the liquid lubricant to be proportioned, a first liquid communication element that is disposed between the inlet 102 of the pump element 100 and the storage unit 3 and arranged to establish liquid communication between the inlet 102 and the storage unit 3. The first liquid communication element may comprise a duct. The pump 1 further comprises a second liquid communication element that is disposed between the second outlet 109 of the pump element 100 and the storage unit 3 and is arranged to establish liquid communication between the second outlet 109 and the storage unit 3. The second liquid communication element may comprise a duct. In this way, a return path from the dosage chamber 107 to the storage unit 3 is provided for the predetermined charge 112 of the liquid lubricant that cannot be dispensed via the first outlet 103.

The pump 1 according to the invention is operable by direct current, DC, electrical power. In this way, application of the pump in industrial equipment that generally do not comprise pressurized air is enabled.

Figure 4 shows a schematic layout of a first embodiment of a lubrication system 200 according to the invention for dispensing predetermined charges of a liquid lubricant to lubrication points of industrial equipment. The lubrication system 200 comprises a pump 1 according to the invention comprising two pump elements 100 as shown in figures 2a to 2f.

The first embodiment of the lubrication system 200, which may be a progressive centralized lubrication system, further comprises a third 201 and a fourth 203 liquid communication element and a first 202 and a second 204 progressive block.

The third 201 and fourth 203 liquid communication elements may comprise ducts. The third liquid communication element 201 is disposed between the first outlet 103 of one of the two pump elements 100 and the first progressive block 202 for establishing liquid communication between said first outlet and first progressive block 202, i.e. for providing predetermined charges of the liquid lubricant to the first progressive block. The fourth liquid communication element 203 is disposed between the first outlet of the other one of the two pump elements 100 and the second progressive block 204 for establishing liquid communication between said first outlet and second progressive block 204, i.e. for providing predetermined charges of the liquid lubricant to the second progressive block.

Each progressive block comprises at least one modular divider that is configured for providing at least a part of the predetermined charge of the liquid lubricant to at least one lubrication point that needs to be lubricated.

Accordingly, it has been described that the invention relates to a pump element 100 for use in a lubrication system 200 for dispensing predetermined charges 112 of a liquid lubricant to lubrication points of industrial equipment. The pump element 100 comprises a dosage chamber 107 for forming said predetermined charges 112 of the liquid lubricant and a first outlet 103 that is arranged in liquid communication with said dosage chamber 107 to dispense said predetermined charge 112 of the liquid lubricant. The pump element 100 further comprises a piston 105 having a pressure relief liquid flow path 108 in which a safety relief valve 110 is disposed. In case the predetermined charge 112 of the liquid lubricant cannot flow out of the first outlet 103, pressure rising in the dosage chamber 107 is limited by opening of the safety relief valve 110 when the pressure in the dosage chamber 107 reaches a predetermined threshold value. The invention also relates to a pump 1 and a lubrication system 200, e.g. a progressive centralized lubrication system, comprising the proposed pump element 100.

In the foregoing description of the drawings, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications/additions and/or changes/substitutions may be made thereto without departing from the scope of the invention as summarized in the attached claims.

In particular, combinations of specific features of various aspects of the invention may be made. An aspect of the invention may be further advantageously enhanced by adding a feature that was described in relation to another aspect of the invention.

It is to be understood that the invention is limited by the annexed claims and its technical equivalents only. In this document and in its claims, the verb "to comprise" and its conjugations are used in their non-limiting sense to mean that items following the word are included, without excluding items not specifically mentioned. In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one".

Claims (15)

A pump element (100) for use in a lubrication system (200) for delivering predetermined charges (112) of a liquid lubricant to lubrication points of industrial equipment, the pump element (100) comprising a housing (101) provided from an inlet (102) configured to allow a stream of a liquid lubricant to be metered to flow into the pump element (100); a first outlet (103) configured to deliver a predetermined charge (112) of said flow of the liquid lubricant; a first liquid flow path (104) arranged between and in liquid communication with the inlet (102) and the first outlet (103); and a piston (105) and a first one-way passage device (106) disposed in said first liquid flow path (104) thereby defining a metering chamber (107) for forming the predetermined charge (112) of said flow of the liquid lubricant, the piston (105) being movable between a first position in which the piston (105) allows said flow of the liquid lubricant to flow into the metering chamber (107) and a second position in which the piston (105) is configured to prevent communication between the inlet (102) and the metering chamber (107), wherein when moving the piston (105) from the first to the second position, said piston (105) fluid communication between the inlet (102) and the metering chamber (107) and pushes said predetermined charge of the liquid lubricant from the metering chamber (107) into the first outlet (103) via the first one-way passage device (106) configured urinated to prevent said predetermined charge (112) of the liquid lubricant from flowing back from the first outlet (103) into the metering chamber (107); said piston (105) comprising a second liquid flow path (108) arranged between and in fluid communication with said dosing chamber (107) and a second outlet (109) configured to allow said predetermined charge (112) of the liquid lubricant from said metering chamber (107) can flow out of the pump element (100); and a second one-way passage device (110) disposed in said second liquid flow path (108), the second one-way passage device (108) configured to allow liquid communication between said metering chamber (107) and the second outlet (109) when a pressure in said metering chamber (107) reaches a predetermined threshold value. The pump element (100) according to claim 1, wherein the second one-way passage device (110) is a safety valve. The pump element (100) according to claim 1 or 2, wherein the predetermined threshold value is 275 ± 10% bar. The pump element (100) according to any of the preceding claims, wherein the first one-way passage device (106) is a non-return valve. The pump element (100) according to any of the preceding claims, wherein the first (104) and second (108) liquid flow paths comprise at least one of boreholes and conduits. The pump element (100) according to any of the preceding claims, wherein the dosing chamber (107) has a predetermined volume in a range of 0.1 to 0.3 cm 3 A pump (1) for use in a lubrication system (200) for delivering predetermined charges (112) of a liquid lubricant to lubrication points of industrial equipment, the pump (1) comprising a pump element (100) according to one of the preceding claims. The pump (1) according to claim 7, further comprising a cam device (7) arranged to communicate with the piston (105) of the pump element (100) and to drive said piston (105) between the said first and second positions. The pump (1) according to claim 7 or 8, further comprising a storage unit (3) comprising the liquid lubricant to be dosed; a first fluid communication element disposed between the inlet (102) of the pump element (100) and the storage unit (3) and arranged to establish fluid communication between said inlet (102) and the storage unit (3); and a second fluid communication element disposed between the second outlet (109) of the pump element (100) and the storage unit (3) and arranged to establish fluid communication between said second outlet (109) and the storage unit ( 3). The pump (1) according to claim 9, wherein the first and second liquid communication elements comprise lines. The pump (1) according to any of claims 7 to 10, wherein the pump (1) is drivable by electrically direct current. A lubrication system (200) for delivering predetermined charges (112) of a liquid lubricant to lubrication points of industrial equipment comprising a pump (1) according to any of claims 7 to 11. The lubrication system (200) according to claim 12, wherein said lubrication system (200) is a progressively centralized lubrication system. The lubrication system (200) of claim 13, further comprising a third fluid communication element (201) and a first progressive block (202), wherein the third fluid communication element (201) is disposed between the first outlet (103) of the pump element (100) and the first progressive block (202) and arranged to establish fluid communication between said first outlet (103) and first progressive block (202). The lubrication system (200) of claim 14, wherein the third fluid communication element comprises a conduit.