Technical field
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The technology proposed herein relates to the prevention of microbiological growth in processing equipment.
Background
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Microbiological growth in processing equipment is a recognized problem. This is particularly the case for food processing equipment, such as in diary processing. The feed that is processed have a high nutrient content and the rate of microbiological growth in the equipment is typically high. Extensive biofilms can form in a few hours. Frequent cleaning is typically required to prevent a drop in quality of the produced product or in the performance of the equipment. For example, microbiological growth may contaminate the produced product, or it may obstruct the flow of the fluid within the equipment. Microbiological growth can further form in hydraulic fluids, leading to a deteriorated performance of the hydraulic system.
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Typically, production must be interrupted for cleaning and chemicals are commonly used, which contributes to a decreased efficiency and increased production costs. Microbiological growth is particularly a problem in equipment that that cannot easily be disassembled for manual cleaning.
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Microbiological growth in hydraulic equipment is also a recognized problem. This is particularly the case if biodegradable hydraulic fluids are used, or if the hydraulic fluid contains water.
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Equipment having reciprocating elements, such as piston pumps, plunge pumps, rotary pistons pumps, and hydraulic cylinders, are typically difficult to clean using chemicals, since they must be operated in the process. Disassembly for manual cleaning may also be difficult. Thus, there is a need for reducing microbiological growth in such equipment.
Object of the proposed technology
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The proposed technology aims at preventing or reducing microbiological growth, such as the formation of biofilms, in equipment having a reciprocating element. A particular object of the proposed technology is to prevent or reduce the formation of biofilms in such equipment employed in food processing or hydraulic applications.
Summary
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In a first aspect of the proposed technology, a system is proposed that comprises: a housing, or container, and an electric power source, or electric power supply. The housing is electrically conductive and arranged to hold, or contain, a fluid, the power source is arranged to supply an electric current, and/or an electric potential, and the housing and the electric power source are operationally coupled in an electric circuit arranged to lead the current from the electric power source through, or via, the housing, and/or to establish the potential over the housing. The electric current, and/or the electric potential, is configured to inhibit, reduce, or prevent, microbiological growth within the housing, or on the housing.
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The system further comprises a reciprocating element. The reciprocating element is located at least partly within the housing. It is understood that the reciprocating element may be arranged to reciprocate relative to the housing. It is further understood that the reciprocating element may be arranged to reciprocate along a reciprocating-element axis, or first axis. It is specified that the housing is arranged to hold, or contain, a fluid. More specifically, the housing and the reciprocating element may be arranged to jointly hold, or contain, the fluid.
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It is understood that the reciprocating element may be electrically conductive. It is further understood that the reciprocating element and the housing may be electrically coupled in an electric network, and that the electric network may form part of the electric circuit. More generally, the reciprocating element may form part of the electric circuit. This means that the housing, electric power source, and reciprocating element are operationally coupled in the electric circuit, and the electric circuit is arranged to lead the current from the electric power source through, or via, the housing and the reciprocating element, and/or to establish the potential over the housing and the reciprocating element. It is further understood that the electric current, and/or the electric potential, may be further configured to inhibit, reduce, or prevent microbiological growth on the reciprocating element.
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The complete reciprocating element may be located within the housing. Worded differently, the housing may enclose the reciprocating element. Alternatively, the reciprocating element may extend from within the housing to outside the housing. Worded differently, the reciprocating element may at least partly be located within the housing, or it may be accessible from outside the housing.
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It is understood that the intention of the system is to prevent microbiological growth in the housing and on the reciprocating element. It is further understood that the housing and the reciprocating element may form part of a food processing equipment or a hydraulic equipment.
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It is further understood that the housing has a portion that is exposed to the fluid, and the electric circuit may be arranged to lead the current from the electric power source through, or via, the portion exposed to the fluid. It is further understood that the current is adapted to inhibit microbiological growth on the housing or on the portion of the housing that is exposed to the fluid. It is specified that the electric circuit is arranged to lead the current through the housing. It is further understood that the portion of the housing may form part of the electric circuit. This means that the current passes through, or via, the portion. The complete housing may form part of the electric circuit, which means that the current passes through the complete housing. It is understood that the current may be evenly or unevenly distributed in the housing.
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Throughout these specifications, if a first element is electrically coupled to a second element, there may be further conductive elements between them, and if a first element is electrically connected to a second element, there are no conductive elements between them.
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The fluid may be susceptible to microbiological growth. The fluid may contain water and/or oil. The fluid may be a liquid in food processing, such as raw milk or raw juice. It is understood that the fluid may contain solid particles. A fluid is here understood to include liquids and gases. The fluid may be a paste, or a minced or pureed product. The fluid may be a hydraulic fluid, or hydraulic liquid. It is understood that a hydraulic fluid is a medium by which power is transferred in a hydraulic machinery. It is further understood that the hydraulic fluid may comprise oil or water, or a combination of both.
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The electric circuit may be coupled to, or connected to, ground. Worded differently, the housing may be electrically coupled to the power source via ground, or the electric circuit may incorporate ground. Ground may be signal ground or earth ground. For example, ground may incorporate an electrically conductive structure connected to and supporting the housing.
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The power source may have a first terminal and a second terminal. The first terminal may supply the current or the potential. The first terminal may be coupled to the housing or the reciprocating element. The second terminal may be coupled to the housing or the reciprocating element via ground. In this context, it is understood that the potential is relative to ground. The power source may be a single-phase power source. This means that it has a single terminal supplying the current or the potential, for example by the first terminal.
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The current may be an alternating current. An alternating current is understood to periodically change direction. The current may have a square waveform. The current may be below 10 mA, below 1 mA, or below 0.1 mA. The current may be greater than 0.01 mA. The current may be in the range 10 mA to 1 mA, 1 mA to 0.1 mA, or 0.1 mA to 0.01 mA. Here, the current is understood as the absolute maximum over a period. It has been found that this current is sufficient for inhibiting microbiological growth. The alternating current may have a frequency below 100 Hz, below 10 Hz, or below 1 Hz. The frequency may be greater than 0.1 Hz. The alternating current may be supplied at a peak voltage below 120 V, in the range 10 V to 100 V, or in the range 20 V to 90 V, or in the range 30 V to 70 V.
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Alternatively to the current being an alternating current, the current may be a direct current. A direct current is understood to have a constant direction. The direct current may be a pulsed current. It is understood that no current is supplied between pulses. The pulsed current may have a regular pulse frequency. The pulse frequency may be below 100 Hz, below 10 Hz, or below 1 Hz. The pulse frequency may be greater than 0.1 Hz. The direct current may have a duty cycle in the range 60% to 40%, or about 50%. For example, the current may be supplied with a pulse length of 500 ms with a pulse separation of 500 ms. The pulsed current may be supplied at a peak voltage below 120 V, in the range 10 V to 100 V, or in the range 20 V to 90 V, or in the range 30 V to 70 V.
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The housing may be of metal, such as steel or an aluminium alloy. The housing may form, or enclose, an inner space for holding, or retaining, the fluid. The housing may have a wall forming the inner space for holding the fluid. It is understood that the wall is exposed to the fluid. The wall may be electrically conductive. For example, the wall may be of metal. It is understood that the housing, or wall, may be composed of several components that are connected, or joined, together. The wall may be, or form part of the abovementioned portion of the housing.
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The housing may have, or form, an inlet, or feed nozzle, configured to receive, or introduce, the fluid into the housing. The housing may have, or form, an outlet, or discharge nozzle, configured to discharge, or dispel, the fluid from the housing. More generally, the housing may have a first port configured to introduce the fluid into and/or dispel the fluid from the housing. Additionally, the housing may have a second port configured to introduce the fluid into and/or dispel the fluid from the housing. The inlet and the outlet, or the first port and the second port, may be located at opposite sides, or ends, of the housing. It is understood that the housing may be exposed to the fluid between the inlet and the outlet, or between the first port and the second port.
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The electric circuit may be coupled to, or connected to, the housing at, or via, the inlet and/or at the outlet, or at, or via, the first port and/or the second port. This contributes to inhibit microbiological growth between the inlet and/or the outlet, or between the first port and/or the second port. If the inlet and the outlet, or the first port and the second port, are located at opposite sides of the housing, microbiological growth in the complete housing may thus be inhibited.
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The housing may be a static housing, or stationary housing. It is understood that a static housing does not move in use. The system may further comprise a support structure that fixedly supports the housing. The housing may be electrically connected to, or coupled to, the support structure. The support structure may be electrically coupled to ground. For example, it is specified above that the second terminal of the electric power source may be coupled to the housing via ground, and the second terminal may further be coupled to the housing via the support structure. Alternatively, the housing may be electrically insulated from the support structure, or from ground. This may contribute to an improved control of the electric current in the housing, and in extension to an improved reduction of microbiological growth.
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The system may further comprise a feed pipe connected to the inlet of the housing and arranged to lead the fluid to the inlet. More generally, the system may further comprise a first pipe connected to the first port and arranged to lead the fluid to and/or from the first port. Similarly, the system may further comprise a discharge pipe connected to the outlet of the housing and arranged to lead the fluid from the outlet. More generally, the system may further comprise a second pipe connected to the second port and arranged to lead the fluid to and/or from the second port.
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The feed pipe and/or the discharge pipe, or more generally the first pipe and/or the second pipe, may be electrically conductive. For example, they may be of metal, such as steel or an aluminium alloy. The feed pipe and/or the discharge pipe, or more generally the first pipe and/or the second pipe, may be electrically connected to the housing, for example by directly contacting the housing. It is understood that this may be via the inlet and/or the outlet, or more generally via the first port and/or the second port. The feed pipe and/or the discharge pipe, or more generally the first pipe and/or the second pipe, may form part of the abovementioned electric circuit.
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The electric circuit may be arranged to lead the current through, or via, the feed pipe and/or the discharge pipe, or more generally via the first pipe and/or the second pipe. Worded differently, the electric circuit may be arranged to establish the potential over the housing via the feed pipe and/or the discharge pipe, or more generally via the first pipe and the second pipe. The electric circuit may be arranged to lead the current through and/or to establish the potential over at least a portion of the feed pipe and/or over at least a portion of the discharge pipe, or more generally to lead the current through and/or to establish the potential over at least a portion of the first pipe and/or over at least a portion of the second pipe. This means that there may be parts of the feed pipe and/or discharge pipe, or more generally the first pipe and/or the second pipe, through which the current does not run. The electric circuit may be arranged to lead the current through and/or to establish the potential over the complete feed pipe and/or the complete discharge pipe, or more generally over the complete first pipe and/or the complete second pipe.
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Alternatively to the feed pipe and/or the discharge pipe, or more generally the first pipe and/or the second pipe, being electrically conductive, they may be electrically insulating. For example, they may be of plastic.
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It is specified that the system comprises a reciprocating element that is located at least partly within the housing. More specifically, the reciprocating element may be located at least partly within the inner space.
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The reciprocating element may be a rigid structure. It may further be detached, or unfastened, from the housing. Worded differently, the reciprocating element may be slidably supported by the housing. For example, the reciprocating element may be a piston. It is understood that the reciprocating element is exposed to the fluid within the housing.
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The reciprocating element may be electrically conductive. For example, the reciprocating element may be of metal, such as steel or an aluminium alloy.
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The system may further comprise a shaft arrangement that is connected to the reciprocating element. The shaft arrangement may extend from within the housing to outside the housing. The shaft arrangement may be arranged to drive, or move, the reciprocating element, for example in a reciprocating pump application. Worded differently, the shaft arrangement may be arranged to, or intended to, move the reciprocating element relative to the housing. Alternatively, the shaft arrangement may be arranged to be driven by the reciprocating element, for example in a hydraulic cylinder application. Worded differently, the reciprocating element may be arranged to, or intended to, move the shaft arrangement relative to the housing.
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The reciprocating element and the shaft arrangement may jointly form an articulated structure, for example in a reciprocating pump application. Alternatively, the reciprocating element and the shaft arrangement may jointly form a rigid structure, for example in a hydraulic cylinder application.
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It is specified that the reciprocating element may be electrically conductive. The shaft arrangement may be electrically conductive. For example, the shaft arrangement may be of metal, such as steel or an aluminium alloy. It is understood that the shaft arrangement may be electrically coupled to, or electrically connected to, the reciprocating element. The shaft arrangement may form part of the abovementioned electric circuit. The electric circuit may be arranged to lead the current through, or via, both the housing and the reciprocating element, and/or to establish the potential over the housing and the reciprocating element. More specifically, the electric circuit may be arranged to lead the current through, or via, the housing, the reciprocating element, and the shaft arrangement, and/or to establish the potential over the housing, the reciprocating element, and the shaft arrangement.
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The shaft arrangement may be exposed to the fluid, for example in a hydraulic cylinder application. It is specified that the shaft arrangement may form part of the abovementioned electric circuit. This way, the electric current, and/or the electric potential, is further configured to inhibit, reduce, or prevent microbiological growth on the shaft arrangement.
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The electric circuit may be arranged to lead the current through and/or to establish the potential over at least a portion of the reciprocating element and/or over at least a portion of the shaft arrangement. This means that there may be parts of the reciprocating element and/or shaft arrangement through which the current does not run. The electric circuit may be arranged to lead the current through and/or to establish the potential over the complete the complete reciprocating element and/or over the complete shaft arrangement.
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It is specified that the reciprocating element and the housing may be electrically coupled in an electric network. The electric network may be arranged to distribute the current between the housing and the reciprocating element. For example, the housing and the reciprocating element may be arranged in parallel in the electric network. This means that in the electric network, a first portion of the current is conducted through, or via, the housing and a second portion of the current is conducted through, or via, the reciprocating element. Alternatively, the housing and the reciprocating element may be arranged in series in the electric network. This means that in the electric network, the same current is conducted through the housing and the reciprocating element. It is understood that the reciprocating element, the shaft arrangement, and the housing may be electrically coupled in the electric network.
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The reciprocating element may be electrically coupled to the housing. The reciprocating element may contact the housing in operation. Alternatively, the system may comprise a first internal connector, or first internal connector arrangement, that electrically couples the reciprocating element and the housing. Worded differently, the reciprocating element may be electrically coupled to the housing via the first internal connector. The system may further comprise a second internal connector, or second internal connector arrangement, that electrically couples the shaft arrangement and the housing. Worded differently, the reciprocating element may be electrically coupled to the housing via the second internal connector.
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The first internal connector may be a sliding electrical connector, or electrical sliding joint. The second internal connector may be a rotary electrical connector, or electrical rotary joint, for example in a reciprocating pump application. Alternatively, the second internal connector may be a sliding electrical connector, or electrical sliding joint, for example in a hydraulic cylinder application. Here, rotary electrical connectors are understood to allow a transmission of electrical power or electrical signals from a stationary structure to a rotating structure, and sliding electrical connectors are understood to allow a transmission of electrical power or electrical signals from a stationary structure to a sliding structure.
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The first internal connector and the second internal connector may be spaced apart along the reciprocating element axis, for example in a reciprocating pump application. They may be centred on the reciprocating element axis, for example in hydraulic cylinder applications.
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The first internal connector may comprise an electrically conductive first seal, for example of metal. It is understood that the first seal may electrically couple, or electrically connect, the reciprocating element and the housing. Worded differently, the reciprocating element may be electrically coupled to the housing via the first seal. It is understood that the first seal may be arranged to inhibit, or prevent, a fluid to pass between the reciprocating element and the housing. A fluid is here understood to include liquids and gases. It is further understood that the first seal may be a mechanical seal. The first seal may be attached to, or fixed to, the reciprocating element, for example in piston pump applications and hydraulic-cylinder applications. Alternatively, the first seal may be attached to, or fixed to, the housing, for example in plunger-pump applications and hydraulic-cylinder applications.
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The first internal connector may comprise an electrically conductive linear wear ring or guide ring, linear plain bearing, or linear bushing, for example of metal. It is understood that the wear ring or guide ring may electrically couple, or electrically connect, the reciprocating element and the housing. It is understood that the wear ring or guide ring may be arranged to space the reciprocating element apart from the housing. The wear ring or guide ring may be attached to, or fixed to, the reciprocating element, for example in piston pump applications. Alternatively, the wear ring or guide ring may be attached to, or fixed to, the housing, for example in plunger-pump applications.
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The second internal connector may comprise an electrically conductive second seal, for example of metal. It is understood that the second seal may electrically couple, or electrically connect, the reciprocating element and the housing. Worded differently, the reciprocating element may be electrically coupled to the housing via the second seal. It is understood that the second seal may be arranged to inhibit, or prevent, a fluid to pass between the shaft and the housing. A fluid is here understood to include liquids and gases. It is further understood that the second seal may be a mechanical seal. The second seal may be attached to, or fixed to, the housing, for example in hydraulic-cylinder applications.
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The second internal connector may comprise a bearing, such as a metal rolling element bearing or a metal plain bearing connecting the shaft arrangement and the housing, for example in a reciprocating pump application with a shaft arrangement having a crankshaft. Additionally or alternatively, the second internal connector may comprise a metal brush or carbon brush connecting the shaft arrangement and the housing.
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The second internal connector may comprise an electrically conductive linear wear ring or guide ring, linear plain bearing, or linear bushing, for example of metal. It is understood that the wear ring or guide ring may electrically couple, or electrically connect, the shaft arrangement and the housing. It is understood that the wear ring or guide ring may be arranged space the shaft arrangement apart from the housing. The wear ring or guide ring may be attached to, or fixed to, the housing, for example in hydraulic cylinder applications.
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On a more general level, the reciprocating element, or the reciprocating element and the shaft arrangement, may be coupled to, or connected to the electric circuit via the housing. For example, the abovementioned second portion of the current may pass through, or via, the housing before and/or after passing through, or via, the reciprocating element. The housing may be coupled to, or connected to, the electric circuit via the reciprocating element, or via the reciprocating element and the shaft arrangement. For example, the abovementioned first portion of the current may pass through, or via, the reciprocating element before and/or after passing through, or via, the housing.
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The system may further comprise: a first connector, or first connector arrangement connected to the housing, wherein the housing is electrically coupled to the power source via the first connector. This means that the first connector forms part of the abovementioned electric circuit. The system may further comprise: a second connector, or second connector arrangement connected to the housing, wherein the housing is electrically coupled to the power source via the second connector. This means that the second connector forms part of the abovementioned electric circuit. The abovementioned support structure may constitute, or form, the second connector, and the support structure may be connected to ground.
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The first connector and the second connector may be positioned on opposite sides of the housing, or the inner space. The abovementioned inlet and/or outlet may be located between the first connector and the second connector. This contributes to inhibit microbiological growth withing a greater part of the housing.
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The abovementioned first internal connector and/or second internal connector may be located between the first connector and the second connector. This contributes to inhibit microbiological growth over a greater part of the reciprocating element or shaft arrangement.
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It is specified above that the housing may be a static housing. The first connector may be connected to the housing. Similarly, the second connector may be connected to the housing. In this configuration, any of the first connector and the second connector may be a static connector, or a fixed connector. This means that the connector cannot move relative to the housing. For example, the static connector may be a ring lug connector secured to the housing by a screw.
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It is further specified above that the system comprises a reciprocating element that is arranged to reciprocate along a reciprocating-element axis. If both the first connector and the second connector are connected to the housing, the current may then be distributed to the reciprocating element via the abovementioned first internal connector and/or second internal connector. The first connector and the second connector may be spaced apart along the reciprocating-element axis. This contributes to a inhibit microbiological growth over a greater part of the reciprocating element, particularly if the abovementioned first internal connector and second internal connector are present and spaced apart along the reciprocating-element axis.
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It is specified above that the system may comprise a feed pipe and/or a discharge pipe, or a first pipe and/or a second pipe. The first connector may be connected to the feed pipe, or the first pipe. Similarly, the second connector may be connected to the discharge pipe, or the second pipe. This contributes to reduce microbiological growth also in the feed pipe and/or discharge pipe, or in the first pipe and/or the second pipe.
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It is specified that the first connector is connected to the housing, wherein the housing is electrically coupled to the power source via the first connector. Similarly, it is specified that the second connector is connected to the housing, wherein the housing is electrically coupled to the power source via the second connector. Alternatively, the first connector may be connected to the shaft arrangement, wherein the shaft arrangement is electrically coupled to the power source via the first connector. Similarly, the second connector may be connected to the shaft arrangement, wherein the shaft arrangement is electrically coupled to the power source via the second connector. Alternatively, the first connector may connect to the inlet or the outlet, or to the first port or the second port. Similarly, the second connector may connect to the inlet or the outlet, or to the first port or the second port. It is understood that if the first connector is connected to the inlet, or first port, the second connector is connected to the outlet, or second port, and vice versa. It is described above that the system may comprise a feed pipe and a discharge pipe, or a first pipe and a second pipe. Alternatively, the first connector may be connected to the feed pipe, or to the first pipe. Similarly, the second connector may be connected to the discharge pipe, or the second pipe.
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The system may further comprise an electric first wire, and the first connector may be connected to the power source by the first wire. The first wire may be connected to the abovementioned first terminal of the power source. The system may further comprise an electric second wire, and the second connector may be connected to the power source by the second wire. The second wire may be connected to the abovementioned second terminal of the power source. Alternatively, the second connector may be coupled to the power source, or the second terminal of the power source via ground, for example via the abovementioned support structure.
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The housing and the reciprocating element may form part of a positive-displacement pump. Wording the first aspect of the proposed technology differently, the system comprises an electric power source, or electric power supply, and a positive-displacement pump having a housing and a reciprocating element. The housing is electrically conductive and arranged to hold, or contain, a fluid. The power source is arranged to supply an electric current, and/or an electric potential, and the housing and the electric power source are operationally coupled in an electric circuit arranged to lead the current from the electric power source through, or via, the housing, and/or to establish the potential over the housing. The electric current, and/or the electric potential, is configured to inhibit, reduce, or prevent microbiological growth within the housing, or on the housing. More specifically, the fluid may be a liquid.
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It is understood that the system may have any of the features described above. For example, the housing may be a static housing, and the system may comprise a shaft arrangement. It is further understood that the inner space is a compression chamber.
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The positive-displacement pump may be a piston pump or a plunger pump. The reciprocating element is then a piston respective a plunger.
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The shaft arrangement may comprise a connecting rod and a crankshaft, wherein the crank shaft is connected to the piston or plunger via the connecting rod. It is understood that the crankshaft is operationally connected to the piston or plunger via the connecting rod and arranged to reciprocate the piston or plunger at a rotation of the crankshaft. It is further understood that the connecting rod is rotationally connected to the crankshaft and pivotally connected to the piston or plunger. It is further understood that the crankshaft and the connecting rod are arranged to convert a rotation of the crankshaft to a reciprocating linear motion of the piston or plunger inside the housing, or more specifically within the inner space. More specifically, the crankshaft may have, or form, a crank pin, the shaft arrangement may have a rod bearing, and the connecting rod may be connected to the crank pin via the rod bearing. For example, the rod bearing may be a rolling element bearing. The shaft arrangement may comprise a piston pin, or plunger pin, that pivotally connects the connecting rod to the piston or plunger. Worded differently, the connecting rod may be pivotally connected to the piston via the piston pin, or the connecting rod may be pivotally connected to the plunger via the plunger pin. It is understood that the crankshaft has a crankshaft axis and that it is arranged to rotate around the crankshaft axis. It is further understood that the crankshaft axis may be perpendicular to the reciprocating-element axis.
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Alternatively to the crankshaft, the shaft arrangement may comprise a linear rod, or push rod, arranged to reciprocate the piston or plunger at a reciprocating linear motion of the linear rod. It is understood that the linear rod has a linear-rod axis and that it is arranged to reciprocate along the linear-rod axis. The linear rod and the reciprocating element may be coaxial. Worded differently, the linear-rod axis and the rotating-element axis may be colinear and overlapping.
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For example, the linear rod may be configured to be operated by a linear actuator, such as an electromechanical actuator or a hydraulic cylinder. Alternatively, the shaft arrangement may further comprise a swashplate and a rotary shaft, wherein the swashplate operationally connects the linear rod to the rotary shaft and is arranged to reciprocate the linear rod at a rotation of the rotary shaft. It is understood that the rotary shaft has a rotary-shaft axis and that it is arranged to rotate around the rotary-shaft axis. For example, the rotary shaft may be configured to be operated by an electric motor. The rotary shaft may be off-axis relative to the reciprocating element. Worded differently, the linear-rod axis and the rotating-element axis may be parallel and non-overlapping.
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In the piston pump, it is understood that the housing, or the wall of the housing, may comprise a cylinder block that forms a cylinder in which the piston can reciprocate. This means that the inner space is partly formed by the cylinder block. The housing, or the wall of the housing, may further comprise a cylinder head that is attached and sealed to the cylinder block, and the cylinder block and the cylinder head jointly form, or enclose, the inner space.
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It is specified above that the shaft arrangement may be electrically conductive. It is understood that the components of the shaft arrangement may be electrically coupled to one another. If the shaft arrangement has a crankshaft, the piston pin, connecting rod, rod bearing, and crankshaft may be of metal, such as steel. If the shaft arrangement has a linear rod, the linear rod may be of metal, such as steel. If the shaft arrangement has a swashplate, the linear rod, swash plate, and rotary shaft may be of metal, such as steel. It is understood that the components of the shaft arrangement may be electrically connected. It is specified that shaft arrangement may be electrically coupled, or electrically connected, to the reciprocating element. For example, the piston pin or the linear rod may be electrically connected to the piston. Worded differently, or the connecting rod or the linear rod may be electrically coupled to the piston.
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It is specified above that the first internal connector electrically couples the reciprocating element and the housing. In the piston pump, the first internal connector may be attached to, or fixed to, the reciprocating element. In the plunger pump, the first internal connector may be attached to, or fixed to, the housing. For example, the first internal connector may comprise an electrically conductive first seal and/or wear ring.
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It is specified above that the second internal connector electrically couples the shaft arrangement and the housing. It is further specified that the second internal connector may be a rotary electrical connector. For example, the second internal connector may connect to the crankshaft or the rotary shaft. The second internal connector may comprise a bearing, such as a metal rolling element bearing or a metal plain bearing connecting the crankshaft or rotary shaft and the housing. Additionally or alternatively, the second internal connector may comprise a wear ring or guide ring attached to the crankshaft or rotary shaft, or to the housing, that connects the shaft arrangement and the housing.
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It is specified above that the second internal connector may be a sliding electrical connector. If the shaft arrangement has a linear rod, the second internal connector may connect to the linear rod. The second internal connector may then comprise a bearing, such as metal plain bearing connecting the linear rod and the housing. Additionally or alternatively, the second internal connector may comprise a wear ring or guide ring attached to the linear rod, or to the housing, that connects the shaft arrangement and the housing.
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The first connector may connect to the housing or the shaft arrangement and the second connector may connect to the housing, or vice versa. The first internal connector may be located between the first connector and the second connector, for example relative to, or in a direction along, the reciprocating-element axis. Similarly, the second internal connector may be located between the first connector and the second connector, for example relative to, or in a direction along, the reciprocating-element axis. Preferably, the second connector is coupled to ground.
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Alternatively, the first connector may connect to the inlet or the outlet. Similarly, the second connector may connect to the inlet or the outlet. It is understood that if the first connector is connected to the inlet, the second connector is connected to the outlet, and vice versa. It is described above that the system may comprise a feed pipe and a discharge pipe. The first connector may then be connected to the feed pipe. Similarly, the second connector may then be connected to the discharge pipe. Alternatively, the second connector may be a rotary connecter that is connected to the shaft arrangement, or to the crankshaft of the shaft arrangement. For example, the rotary connector may be a wear ring or guide ring, plain bearing, or bushing, for example of metal.
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The housing and the reciprocating element may form part of a hydraulic cylinder. Wording the first aspect of the proposed technology differently, the system comprises: an electric power source, or electric power supply, and a hydraulic cylinder having a housing and a reciprocating element. The housing is electrically conductive and arranged to hold, or contain, a fluid. The power source is arranged to supply an electric current, and/or an electric potential, and the housing and the electric power source are operationally coupled in an electric circuit arranged to lead the current from the electric power source through, or via, the housing, and/or to establish the potential over the housing. The electric current, and/or the electric potential, is configured to inhibit, reduce, or prevent microbiological growth within the housing, or on the housing. It is understood that the fluid may be a hydraulic fluid.
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The system may have any of the features described above. For example, the housing may be a static housing, and the system may comprise a shaft arrangement.
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It is understood that the reciprocating element is a piston. It is further understood that the housing, or the wall of the housing, may comprise a cylinder barrel that forms a cylinder in which the piston can reciprocate. The piston may divide the inner space formed by the housing in a first chamber and a second chamber. It is understood that the volumes of the first chamber and the second chamber change at a reciprocation of the piston.
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It is specified that the housing may have a first port configured to introduce the fluid into and/or dispel the fluid from the housing. More specifically, first port may be configured to introduce the fluid into and/or dispel the fluid from the first chamber. For example, this may be in a single-acting or a double-acting hydraulic cylinder. It is specified that the housing may additionally have a second port configured to introduce the fluid into and/or dispel the fluid from the housing. More specifically, second port may be configured to introduce the fluid into and/or dispel the fluid from the second chamber. For example, this may be in a double-acting cylinder.
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The shaft arrangement may comprise a rod that is connected to the piston and extends from within the housing to outside the housing, or that is accessible from outside the housing. The piston and the rod may jointly form a rigid structure. The rod may be centred on, or aligned with, the reciprocating-element axis. It is specified above that the shaft arrangement may be electrically conductive. More specifically, the rod may be electrically conductive. For example, the rod may be of metal, such as steel. It is specified that shaft arrangement may be electrically coupled, or electrically connected, to the reciprocating element. More specifically, the rod may be electrically connected to the piston.
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The housing may form an opening through which the rod extends. More specifically, the housing, or the wall of the housing, may further comprise a cylinder head that is attached and sealed to the cylinder barrel. It is understood that the cylinder head may be electrically connected to the cylinder barrel. The cylinder head may form the opening through which the rod extends.
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In addition to the rod, the shaft arrangement may comprise an additional rod that is connected to the piston and extends from within the housing to outside the housing, or that is accessible from outside the housing. It is understood that that the rod and the additional rod are connected to the piston on opposite sides of the piston, and that the piston is located between the rod and the additional rod. Worded differently, the rod and the additional rod may extend in opposite directions relative to the piston. The piston, the rod, and the additional rod may jointly form a rigid structure. The additional rod may be centred on, or aligned with, the reciprocating-element axis. The additional rod may be electrically conductive. For example, the additional rod may be of metal, such as steel. The additional rod may be electrically connected to the piston.
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The housing may form an additional opening through which the additional rod extends. More specifically, the housing, or the wall of the housing, may further comprise an additional cylinder head that is attached and sealed to the cylinder barrel. It is understood that the additional cylinder head may be electrically connected to the cylinder barrel. The additional cylinder head may form the additional opening through which the additional rod extends. It is understood that that the cylinder head and the additional cylinder head are located at opposite sides of the cylinder barrel.
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It is specified above that the first internal connector electrically couples the reciprocating element and the housing. It is further specified that the first internal connector may be a sliding electrical connector. It is further specified that the first internal connector may comprise an electrically conductive first seal. For example, the first internal connector may comprise electrically conductive first seal attached to the reciprocating element, as described above. It is further specified that the first internal connector may comprise an electrically conductive wear ring or guide ring attached to the reciprocating element.
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It is specified above that the second internal connector electrically couples the shaft arrangement and the housing. More specifically, the second internal connector may electrically couple the rod and the housing, or the rod and the cylinder head. It is further specified that the second internal connector may be a sliding electrical connector. It is further specified that the second internal connector may comprise an electrically conductive second seal, for example of metal. It is understood that the second seal may be arranged to inhibit a fluid to pass between the rod and the housing, or more specifically between the rod and the cylinder head. It is further specified that the second internal connector may comprise a wear ring or guide ring attached to the housing that connects the shaft arrangement and the housing. More specifically, the wear ring or guide ring may connect the rod and the housing, or the rod and the cylinder head. The second seal and/or the wear ring or guide ring may be attached to the cylinder head.
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The system may further comprise an additional second internal connector, or additional second internal connector arrangement, that electrically couples the shaft arrangement and the housing. The additional second internal connector may comprise any of the features of the second internal connector. More specifically, the additional second internal connector may electrically couple the additional rod and the housing, or the additional rod and the additional cylinder head. The additional second internal connector may be a sliding electrical connector. The additional second internal connector may comprise an electrically conductive additional second seal, for example of metal. It is understood that the additional second seal may be arranged to inhibit a fluid to pass between the additional rod and the housing, or more specifically between the additional rod and the additional cylinder head. The additional second internal connector may comprise an additional wear ring or additional guide ring attached to the housing that connects the shaft arrangement and the housing. More specifically, the additional wear ring or guide ring may connect the additional rod and the housing, or the additional rod and the additional cylinder head. The additional second seal and/or the additional wear ring or guide ring may be attached to the additional cylinder head.
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It is specified above that the first internal connector electrically couples the reciprocating element and the housing. Alternatively, the first internal connector may electrically couple shaft arrangement and the housing as described above for the second internal connector. The second internal connector may then electrically couple shaft arrangement and as described above for the additional second internal connector. The reciprocating element may then have no direct electrical coupling to the housing.
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It is specified that the system may comprise a first connector connected to the housing. For example, the first connector may be connected to the housing at the cylinder head, or to the cylinder head. Alternatively, the first connector may be connected to the shaft arrangement. For example, the first connector may be connected to the rod. It is further specified that the system may comprise a second connector connected to the housing. For example, the second connector may be connected to the housing at the additional cylinder head, or to the additional cylinder head. Alternatively, the second connector may be connected to the shaft arrangement. For example, the second connector may be connected to the additional rod.
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The first internal connector may be located between the first connector and the second connector relative to, or in a direction along, the reciprocating-element axis. It is understood that this is at any position of the piston relative to the housing. The second internal connector may be located between the first connector and the second connector relative to, or in a direction along, the reciprocating-element axis. Similarly, the additional second internal connector may be located between the first connector and the second connector relative to, or in a direction along, the reciprocating-element axis. This contributes inhibit microbiological growth in a greater part of the hydraulic cylinder.
Brief description of the drawings
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A more complete understanding of the abovementioned and other features and advantages of the technology proposed herein will be apparent from the following detailed description of preferred embodiments in conjunction with the appended drawings, wherein:
- Fig. 1 is a schematic cross section of a system with a piston pump,
- Fig. 2 is a schematic cross section of another system with a piston pump,
- Fig. 3 is a schematic cross section of a system with a hydraulic cylinder, and
- Fig. 4 is a is a schematic cross section of another system with a hydraulic cylinder another.
Detailed description
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In the figures and the below description, the same reference numerals are used for the same or related features.
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Fig. 1 shows an embodiment of a system 10 that has an electric power source 14 and a positive-displacement pump 56 in the form of a piston pump 56. The pump 56 has static housing 12 and a reciprocating element 34 in the form of an electrically conductive steel piston 34 that is located inside and slidably supported by the housing 12. The housing 12 is of steel and is electrically conductive. The housing 12 and the piston 34 are arranged to jointly hold a fluid.
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The housing 12 has a steel cylinder block 70 that forms a cylinder in which the piston 34 can reciprocate relative to the housing 12 along a reciprocating-element axis 36. The housing 12 further has a steel cylinder head 72 that is attached and sealed to the cylinder block 70. The cylinder block 70 and the cylinder head 72 jointly form an electrically conductive wall 24 that enclose an inner space 22. This means that the inner space 22 is formed partly by the cylinder block 70 and partly by the cylinder head 72, and in extension by the housing 12. It also means that the wall 24, and in extension a portion of the housing 12, are exposed to the fluid. The inner space 22 is a compression chamber in which the piston 34 can reciprocate and is exposed to the fluid.
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The system 10 further has a support structure (not shown) that fixedly supports the housing 12 relative to the surroundings and electrically insulates the housing 12 relative to ground. The housing 12 has an inlet 26 that can receive the fluid into the housing 12 and an outlet 28 that can discharge the fluid from the housing 12. The inlet 26 and the outlet 28 each has a check valve arranged to control the direction of the flow of the fluid. The system 10 further has a feed pipe 30 connected to the inlet 26 that can lead the fluid to the inlet 26 and a discharge pipe 32 connected to the outlet 28 that can lead the fluid from the outlet 28. The feed pipe 30 and the discharge pipe 32 are of steel and contact the inlet 26 respective the outlet 28. This way, they are electrically conductive and electrically connected to the housing 12. In alternative embodiments, the feed pipe 30 and the discharge pipe 32 are not electrically conductive or electrically connected to the housing 12. For example, they are of plastic or separated from the housing 12 by an electrically insulating element, such as a gasket.
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The system 10 further has a shaft arrangement 38 formed by a crankshaft 62, connecting rod 60, crank pin 64, piston pin 68, and rod bearing (not shown). These components are of steel, electrically conductive, and electrically coupled to one another. The piston pin 68 pivotally connects the connecting rod 60 to the piston 34. This way, the shaft arrangement 38 is electrically connected to the piston 34. The crank pin 64 is formed by the crankshaft 62, and the connecting rod 60 is connected to the crank pin 64 via the rod bearing (not shown). The rod bearing (not shown) is a rolling element bearing that rotationally connects the connecting rod 60 to the crankshaft 62. The crankshaft 62 has a crankshaft axis 102 that is perpendicular to the reciprocating-element axis 36 and around which it can rotate. The crankshaft 62 of the shaft arrangement 38 extends from within the housing 12 to outside the housing 12. This way, the piston 34 and the shaft arrangement 38 jointly forms an articulated structure and the shaft arrangement 38 is arranged to drive the piston 34.
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The system 10 has a linear wear ring of metal that is attached to the piston 34 and constitutes a first internal connector 42 that electrically couples the reciprocating element 34 and the housing 12. The system 10 further has a metal rolling element bearing that connects the crankshaft 62 of the shaft arrangement 38 and the housing 12 and constitutes a second internal connector 44 that electrically couples the shaft arrangement 38 and the housing 12. This way, the first internal connector 42 and the second internal connector 44 are spaced apart along the reciprocating element axis 36. The system 10 further has a seal 58 in the form of a piston seal 58 that is attached positioned between the first internal connector 42 and the compression chamber 22 that prevents the fluid from passing between the piston 34 and the housing 12.
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The system 10 further has a first connector 48 and a second connector 50 in the form of ring lug connectors secured and electrically coupled to the housing 12 by screws. The first connector 48 electrically couples the housing 12 to the electric power source 14 via a first wire 52. The first wire 52 is connected to a first terminal 18 of the electric power source 14. The second connector 50 is positioned on an opposite side of the housing 12 relative to the first connector 48 and electrically couples the housing 12 to the electric power source 14 via a second wire 54. The second wire 54 is connected to a second terminal 20 of the electric power source 14.
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The first terminal 18 of the power source 14 can supply an alternating current with a square waveform. The current is about 0.5 mA, has a frequency below of 1 Hz, and is supplied at a peak voltage of about 50 V. The supplied current contributes to reduce microbiological growth in the positive-displacement pump 56.
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With the power source 14, first wire 52, first connector 48, housing 12, first internal connector 42, reciprocating element 34, shaft arrangement 38, second internal connector 44, second connector 50, and second wire 54 arranged as described above, the housing 12, reciprocating element 34, and the electric power 14 source are operationally coupled in an electric circuit 16 that can establish a first electrical potential over the housing 12 and the reciprocating element 34 and lead the electric current from the electric power source 14 and through the housing 12 and the reciprocating element 34. On a more general level, the piston 34 and the housing 12 are electrically coupled in an electric network 40 that forms part of the electric circuit 16.
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The electric circuit 16 can lead the current from the power source 14 through a portion of the housing 12 and the reciprocating element 34 that are exposed to the hydraulic fluid, thus inhibiting microbiological growth on these parts of the system 10. With the described coupling, the shaft arrangement 38, first internal connector 42, and second internal connector 44 form part of the electric circuit 16.
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In alternative embodiments, the first connector 48 is connected to the feed pipe 30 at the inlet 26, and the second connector 50 is connected to the discharge pipe 32 at the outlet 28. With this coupling, the feed pipe 30 and the discharge pipe 32 form part of the electric circuit 16.
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In an alternative embodiment, the system 10 has no second connector 50. Instead, the second terminal 20 of the power source 14 is connected to ground, the housing 12 is electrically connected to the support structure (not shown), and the support structure is connected to ground. Effectively, this means that the support structure (not shown) has the function of the second connector 50 in the electric circuit 16 and it forms part of the electric circuit 16.
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The system 10 further has an electric motor 100 that is connected to the crankshaft 62 of the shaft arrangement 38 outside the housing 12 and arranged to rotate the crankshaft 62 to operate the pump 56.
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Fig. 2 shows another embodiment of a system 10 that has an electric power source 14 and a positive-displacement pump 56 in the form of a piston pump 56. The system 10 shares the features of the system 10 described in relation to Fig. 1, but it differs in that it has no linear wear ring of metal that constitutes a first internal connector 42. Instead, the first internal connector 42 is the piston seal 58, which is of metal and electrically couples the reciprocating element 34 and the housing 12. The system 10 further differs by the first connector 48 being connected to the feed pipe 30 and the second connector 50 being a rotary connecter in the form of a metal wear ring that is connected to the crank shaft of the shaft arrangement 38.
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Fig. 3 shows an embodiment of a system 10 that has an electric power source 14 and a double-acting hydraulic cylinder 74. The hydraulic cylinder 74 has static housing 12 and a reciprocating element 34 in the form of an electrically conductive steel piston 34 that is located inside and slidably supported by the housing 12. The housing 12 is of steel and is electrically conductive.
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The housing 12 has a steel cylinder barrel 78 that forms a cylinder in which the piston 34 can reciprocate relative to the housing 12 along a reciprocating-element axis 36. The housing 12 further has a cylinder head 90 and an additional cylinder head 98 that are attached, sealed, and electrically connected to the cylinder barrel 78. The piston 34 is located in the cylinder barrel 78. This way, the housing 12 forms an inner space 22 that can hold a hydraulic fluid, and the piston 34 divides the inner space 22 in a first chamber 80 and a second chamber 82.
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The system 10 further has a support structure (not shown) that fixedly supports the housing 12 relative to the surroundings and electrically insulates the housing relative to ground. The housing 12 has a first port 26 that can introduce and dispel the hydraulic fluid from the first chamber 80, and a second port 28 that can introduce and dispel the hydraulic fluid from the second chamber 82. The system 10 further has a first pipe 30 connected to the first port 26 that can lead the fluid to and from the first port 26 and a second pipe 32 connected to the second port 28 that can lead the fluid to and from the second port 28. The first pipe 30 and the second pipe 32 are of plastic and electrically insulating.
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The system 10 further has a shaft arrangement 38 in the form of a rod 84 and an additional rod 92 that are connected to the piston 34 and extend from within the housing 12 to outside the housing 12. The rod 84 and the additional rod 92 are of steel and electrically conductive, and they are electrically connected to the piston 34. The piston 34, rod 84, and additional rod 92 jointly form a rigid structure. The piston 34, rod 84, and additional rod 92 are centred on and aligned with the reciprocating-element axis 36. The cylinder head 90 of the housing 12 forms an opening 86 through which the rod 84 extends, and the additional cylinder head 98 of the housing 12 forms an additional opening 94 through which the additional rod 92 extends.
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The system 10 has a sliding electrical connector in the form a wear ring attached to the piston 34 that forms a first internal connector 42 that electrically couples the piston 34 and the housing 12. The system 10 further has first seals 58 attached to the piston 34 on either side of the first internal connector 42 that prevent the hydraulic fluid from passing between piston 34 and the cylinder barrel 78 of the housing 12. The first seals 58 are electrically insulating. In an alternative embodiment they are of metal and form part of the first internal connector 42.
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The system 10 further has sliding electrical connectors in the form of a guide rings supported by the cylinder head 90 respective the additional cylinder head 98. The wear rings constitute a second internal connector 44 and an additional second internal connector 46 that contact and electrically couple the rod 84 respective the additional rod 92 to the housing 12. A second seal 88 is supported by the cylinder head 90 that prevents the hydraulic fluid from escaping between the cylinder head 90 and the rod 84, and an additional second seal 96 is supported by the additional cylinder head 98 that prevents the hydraulic fluid from escaping between the additional cylinder head 98 and the additional rod 92. The second seal 88 and the additional second seal 96 are electrically insulating. In an alternative embodiment they are of metal and form part of the second internal connector 44 respective the additional second internal connector 46.
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The system 10 further has a first connector 48 and a second connector 50 in the form of ring lug connectors secured and electrically coupled to the housing 12 by screws. The first connector 48 electrically couples the housing 12 to the electric power source 14 via a first wire 52. The first wire 52 is connected to a first terminal 18 of the electric power source 14. The second connector 50 is positioned on an opposite side of the housing 12 relative to the first connector 48 and electrically couples the housing 12 to the electric power source 14 via a second wire 54. The second wire 54 is connected to a second terminal 20 of the electric power source 14. The first connector 48 and the second connector 50 are spaced apart along the reciprocating-element axis 36.
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The first terminal 18 of the power source 14 can supply an alternating current with a square waveform. The current is about 0.5 mA, has a frequency below of 1 Hz, and is supplied at a peak voltage of about 50 V. The supplied current contributes to reduce microbiological growth in hydraulic cylinder 74.
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With the power source 14, first wire 52, first connector 48, housing 12, first internal connector 42, reciprocating element 34, shaft arrangement 38, second internal connector 44, additional second internal connector 46, second connector 50, and second wire 54 arranged as described above, the housing 12 and the electric power source 14 are operationally coupled in an electric circuit 16 that can establish a first electrical potential over the housing 12 and the reciprocating element 34 and lead the electric current from the electric power source 14 through the housing 12 and the reciprocating element 34. On a more general level, the piston 34 and the housing 12 are electrically coupled in an electric network 40 that forms part of the electric circuit 16.
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The electric circuit 16 can lead the current from the power source 14 through a portion of the housing 12 that is exposed to the hydraulic fluid, and through the reciprocating element 34 that is exposed to the hydraulic fluid, thus inhibiting microbiological growth on these parts of the system 10. With the described coupling, the shaft arrangement 38, first internal connector 42, second internal connector 44, and additional second internal connector 46 form part of the electric circuit 16.
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Fig. 4 shows another embodiment of a system 10 that has an electric power source 14 and a double-acting hydraulic piston 34. The system 10 shares the features of the system 10 described in relation to Fig. 3, but it differs in that the first connector 48 is connected to the cylinder head 90 and second connector 50 is connected to the additional rod 92. This way, the first internal connector 42, the second internal connector 44, and the additional second internal connector 46 are located between the first connector 48 and the second connector 50 along the reciprocating-element axis 36. In alternative embodiments, the second terminal 20 is connected to ground and the rod 84 and the additional rod 92 are connected to ground.
Item list
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- 10
- system
- 12
- housing
- 14
- electric power source
- 16
- electric circuit
- 18
- first terminal
- 20
- second terminal
- 22
- inner space
- 24
- wall
- 26
- inlet or first port
- 28
- outlet or second port
- 30
- feed pipe or first pipe
- 32
- discharge pipe or second pipe
- 34
- reciprocating element or piston
- 36
- reciprocating-element axis
- 38
- shaft arrangement
- 40
- electric network
- 42
- first internal connector
- 44
- second internal connector
- 46
- additional second internal connector
- 48
- first connector
- 50
- second connector
- 52
- first wire
- 54
- second wire
- 56
- positive displacement reciprocating piston pump
- 58
- seal or first seal
- 60
- connecting rod
- 62
- crankshaft
- 64
- crank pin
- 68
- piston pin
- 70
- cylinder block
- 72
- cylinder head
- 74
- hydraulic cylinder
- 78
- cylinder barrel
- 80
- first chamber
- 82
- second chamber
- 84
- rod
- 86
- opening
- 88
- second seal
- 90
- cylinder head
- 92
- additional rod
- 94
- additional opening
- 96
- additional second seal
- 98
- additional cylinder head
- 100
- electric motor
- 102
- crankshaft axis