Reciprocating piston pump and a method for controlling the reciprocating piston pump

Abstract

The invention relates to a reciprocating piston pump (1, 1') comprising: a pump housing (2) through which a fluid flows; a pump axis (10); and an axially movable pump piston (19) through which fluid flows and which is arranged coaxially with respect to two toroidal coils fixed to the housing, specifically a first toroidal coil (12') and a second toroidal coil (12''), wherein the reciprocating piston pump (1) has two inlet valves, namely a first inlet valve (20') and a second inlet valve (20''), and two outlet valves, specifically a first outlet valve (21') and a second outlet valve (21''), wherein the first inlet valve (20') and the first outlet valve (21') are arranged concentrically with respect to the pump axis (10) within the first toroidal coil (12'), and the second inlet valve (20') and the second outlet valve (21') are arranged concentrically with respect to the pump axis (10) within the second toroidal coil (12''), and the pump piston (19) is guided in a two-part guide sleeve or directly in the pump housing (2) in a two-part displacement chamber.

Description

[0001] Reciprocating piston pump and a method for controlling the reciprocating piston pump

[0002] The invention relates to a reciprocating piston pump with a pump housing through which fluid flows and an axially movable pump piston through which fluid flows and is arranged coaxially with two toroidal coils fixed to the housing.

[0003] The invention also includes a method for controlling a reciprocating piston pump.

[0004] State of the art

[0005] Electric traction drives typically use oil pumps driven by brushless direct current (BLDC) motors. These pumps deliver a flow rate that can be adjusted as needed via the speed control of the BLDC motor, regardless of the vehicle speed. The preferred pump type is a rotating positive displacement pump in the form of annular gear pumps, known as gerotor pumps. The pump consists of a gear set with an inner and outer rotor, as well as a generally two- or three-part pump housing. This simple and proven design nevertheless entails high costs for the motor-pump unit, particularly for the BLDC motor and the required commutation electronics for the motor control, such as the BLDC driver or the B6 bridge circuit.If the commutation electronics are not integrated directly into the motor, but rather into a central transmission control unit or the inverter control board of the electric traction machine, additional costs are incurred for the complex cable harness and connectors.

[0006] While cheaper designs such as brushed DC motors can be easily controlled, they are not wear-free due to the sliding contacts and thus have a significantly reduced service life. Mechanically driven oil pumps, for example, via a transmission intermediate shaft, have the disadvantage that the achievable flow rate depends on the vehicle speed. Thus, under certain operating conditions, such as high torque and low vehicle speed, sufficient cooling oil flow cannot be provided. Furthermore, secondary drives that do not have a mechanical clutch continuously generate drag power.

[0007] Particularly for applications in electric secondary drives, where only very small proportions of active operation and a generally lower cooling oil requirement are required over the entire vehicle service life compared to primary applications, the above-mentioned designs, which are known from the state of the art, do not represent an entirely satisfactory solution, taking into account the cost and efficiency requirements.

[0008] In addition, electromagnetically actuated oscillating piston or diaphragm pumps are already being used in other automotive applications. These pumps, generally designed in-line for direct in-line installation, however, only deliver very low flow rates. They are used as metering pumps for fuel metering for auxiliary heaters and auxiliary heaters, as AdBlue metering pumps, or as fuel metering pumps for exhaust gas thermal management. However, compared to the eDrive oils used in electric drives, they pump significantly lower-viscosity media, such as diesel or AdBlue. Oscillating piston pumps or diaphragm pumps used as metering pumps are generally designed for very low flow rates, and their operation is often audible.

[0009] Impeller or centrifugal pumps are also used as circulation pumps in cooling water circuits. These turbopumps, which operate according to the hydrodynamic principle, require a motor drive and, unlike the positive displacement pumps described above, are not self-priming without additional measures.

[0010] The object of the invention is to propose an improved pump which consists of a cost- and function-optimised electromagnetically actuated reciprocating piston pump with a double-acting pump piston pressurised on both sides and an optional valve for the oil temperature-dependent control of partial volume flows.

[0011] Description of the invention

[0012] The task is solved with a reciprocating piston pump with a fluid-flowing pump housing and an axially movable and fluid-flowing pump piston arranged coaxially to two housing-fixed toroidal coils, wherein inlet valves and outlet valves are arranged concentrically to the pump axis and in the radial direction within the toroidal coils and the pump piston is guided by a two-part guide sleeve or yoke discs arranged directly in the pump housing in a two-part displacement chamber.

[0013] The pump piston integrates the function of a movable armature (armature of the magnetic circuit) and a delivery piston.

[0014] The pump piston is double-acting and can be moved in the axial direction of the reciprocating piston pump.

[0015] Preferably, the pump piston is made of a material with good magnetic conductivity and a high relative permeability, preferably iron (Fe), ferrosilicon (FeSi), or a free-cutting steel (11SMn30). Further advantageously, the first and second bearing bushes are made of a material with good magnetic conductivity and a high relative permeability, preferably iron (Fe), ferrosilicon (FeSi), or a free-cutting steel (11SMn30).

[0016] In an even more advantageous embodiment, the bearing bushes are thick-walled with a wall thickness of 1-3mm.

[0017] In a further development, the two-part guide sleeve comprises a first bearing bush and a second bearing bush, wherein the first and second bearing bush are made of a magnetically insulating material with low relative permeability (p r~ 1 ), the material preferably being aluminium (AI), (EN AW 6062), stainless steel or brass.

[0018] In a further embodiment, the pump piston is coated on its outer surface, or the first and second bearing bushings are coated on their inner surfaces, with a magnetically insulating coating, preferably Teflon or a chromium nitride coating, wherein the coating further advantageously has a layer thickness of 20 to 100 μm. Even more advantageously, the chromium nitride layer thickness is in the range of 20 to 25 μm, and the PTFE layer thickness is in the range of 25 to 50 μm. The coating must be magnetically insulating, highly wear-resistant, and have good sliding properties / low frictional resistance.

[0019] In an alternative design of the guide bushes designed as bearing bushes, these are designed as metal-polymer plain bearing bushes, which consist of a magnetically conductive steel back and a magnetically insulating plain bearing layer.

[0020] By designing the pump piston with a magnetically insulating coating, it can be guided directly within the yoke discs, namely the first and second yoke discs. During axial movement of the pump piston, the pump piston slides on the inner surfaces of the first and second yoke discs via its outer surface or the coating.

[0021] Alternatively, the inner surface of the yoke discs can include the coating.

[0022] A coating with good sliding properties and high wear resistance is, for example, a thin-walled Teflon coating. This allows the pump piston to be guided directly in the coil body made of plastic, e.g., PPS + 50 GF / MD, or on the pole discs made of steel, e.g., 11 SMnPbßO. A costly thin-walled, magnetically insulating stainless steel or brass sleeve is no longer necessary.

[0023] By using two short guide bushings instead of a continuous thin-walled guide sleeve, the two guide bushings, namely the first and the second guide bushing, can also be designed with greater wall thicknesses (1 -3 mm), which in turn makes production easier and more cost-effective.

[0024] In the previously described embodiments, the basic idea is to apply a magnetically insulating coating to components that move relative to one another, which act as magnetic flux guides. The magnetically insulating coating simultaneously performs the following functions: improving wear and friction properties and minimizing magnetic losses.

[0025] The same principle can be achieved by using metal-polymer plain bearing bushings, which consist of a magnetically conductive steel backing and a magnetically insulating plain bearing layer.

[0026] In a further preferred embodiment, a valve is flanged to the outlet side of the reciprocating piston pump and provides two paths. By using this valve for the demand-based control of partial volume flows, e.g. to the stator and rotor of a wet-running, oil-cooled electric motor, the required pump size can be significantly reduced compared to a fixed distribution of partial volume flows. The energy consumption of the pump during operation is also reduced. A pressure-controlled valve cannot be used advantageously due to the inherent flow rate pulsations and the resulting pressure pulsations. Therefore, the use of a temperature-controlled valve with control via a thermosensitive element, e.g. a thermosensitive spring or a wax capsule, is proposed.

[0027] The described embodiment features a pump housing open to the outside. The coolant / lubricant pump located in the fluid sump provides targeted guidance of the inlet and outlet fluid flows for maximum convective heat dissipation through the operating medium.

[0028] The housing-mounted arrangement of the inlet valves and the guidance of the pressure side by the axially movable pump piston offer functional advantages. This eliminates the risk of air separation in the intake line—since there is no need for repeated deflections at sharp edges—and reduces the risk of suction throttling at higher stroke frequencies.

[0029] The problem is also solved by a method for controlling a reciprocating piston pump, wherein the pump piston is controlled via current profiles with positive and negative current pulses.

[0030] In a further development of the inventive concept, it is provided that hydraulic end position damping is carried out by a path-controlled orifice geometry on the pump piston.

[0031] Electromagnetic damping is advantageously achieved through a current profile of the coil current supply. Furthermore, short-term overload operation is possible.

[0032] A further development of the method according to the invention provides for an active distribution of the flow rate via a thermosensitive element.

[0033] A preferred development of the method uses a coil heater for improved low-temperature starting behavior.

[0034] Instead of a rotating one known from the state of the art

[0035] A cost-effective, oscillating positive displacement pump is used. An electromagnetic linear actuator, controlled by a corresponding current profile, actuates a double-acting piston to displace the fluid. The flow rate is controlled by the frequency and amplitude of the current profile.

[0036] Description of the characters

[0037] Figure 1 shows a hydraulic circuit diagram of an electromagnetically actuated reciprocating piston pump according to the invention.

[0038] Figure 2 shows an isometric view of a first embodiment of the electromagnetically actuated reciprocating piston pump according to the invention.

[0039] Figure 3 shows a front view of the reciprocating piston pump shown in Figure 2.

[0040] Figure 4 shows a first sectional view along the section plane AA of the reciprocating piston pump shown in Figures 2 and 3.

[0041] Figure 5 shows a second sectional view along the section plane BB of the reciprocating piston pump shown in Figures 2 and 3. Figure 6 shows a detailed sectional view along the section plane BB of the electromagnetic drive with integrated pump piston and valves of the reciprocating piston pump shown in Figures 2 to 5.

[0042] Figure 7 shows an isometric view of a further embodiment of the electromagnetically actuated reciprocating piston pump according to the invention with an integrated valve for the demand-based control of partial volume flows.

[0043] Figure 8 shows a front view of the reciprocating piston pump shown in Figure 7 with an integrated valve for demand-based control of partial volume flows.

[0044] Figure 9 shows a sectional view of the reciprocating piston pump shown in Figure 7 along the section plane AA.

[0045] Figure 10 shows a sectional view of the reciprocating piston pump shown in Figure 7 along the section plane BB.

[0046] Figure 11 shows a sectional view along the section plane CC.

[0047] Figure 12 shows a sectional view along the section plane DD.

[0048] Figure 13 shows an isometric view of the double coil assembly, without the windings of the toroidal coils shown, of an electromagnetically actuated reciprocating piston pump according to the invention according to Figures 2 to 11.

[0049] Figure 14 shows an end view of the double coil assembly shown in Figure 13.

[0050] Figure 15 shows a sectional view along section plane EE of the double coil assembly shown in Figure 13. Figure 16 shows an isometric view of a yoke disc.

[0051] Figure 17 shows a schematic design for connecting the two electromagnetic coils of a double coil pump according to the invention.

[0052] Figure 18 shows a further schematic embodiment for connecting the two electromagnetic coils of a double coil pump according to the invention.

[0053] Figure 19a and Figure 19b show exemplary current profiles for the electrical control of an electromagnetically actuated double coil pump according to the invention.

[0054] Figure 20 shows a first sectional view along section plane AA in Figure 8 of a further embodiment of the electromagnetically actuated reciprocating piston pump according to the invention with two individual coil assemblies.

[0055] Figure 21 shows a second sectional view along section plane BB in Figure 8 of the electromagnetically actuated reciprocating piston pump according to the invention with two individual coil assemblies.

[0056] Figure 22 shows an isometric view of a coil former with integrated yoke disc.

[0057] Figure 23 shows an end view (view A in Figure 22) of a coil former with integrated yoke disc.

[0058] Figure 24 shows an isometric view of an assembly of a single coil assembly of the reciprocating pump embodiment shown in Figures 20 and 21. Figure 25 shows an end view (view A in Figure 24) of the assembly of the single coil assembly.

[0059] Figure 26 shows a sectional view of the coil former shown in Figures 22 and 23 with integrated yoke disc along section plane FF in Figure 23.

[0060] Figure 27 shows a sectional view of the assembly of the single coil assembly shown in Figures 24 and 25 along section plane GG in Figure 25.

[0061] Figure 28 shows a detailed view of the further embodiment in the area between the yoke discs and the pump piston.

[0062] Figure 29 shows a detailed view of the first embodiment in the area between the two-part guide sleeve and the pump piston.

[0063] Figure 1 shows a hydraulic circuit diagram of an electromagnetically actuated reciprocating piston pump 1 with a suction side 7 and a pressure side 8. A pump piston 19 is actuated via a first coil designed as a toroidal coil 12' and a second coil designed as a toroidal coil 12".

[0064] Possible electrical connections of the first toroidal coil 12' and the second toroidal coil 12" are shown in Figure 17 and Figure 18. Exemplary current profiles for controlling the reciprocating piston pump 1 are shown in Figures 19a and 19b.

[0065] In this embodiment, the pump piston 19, which is actuated from both sides, is actuated in two directions by a double-coil solenoid via the alternating electromagnetic force. Figures 2-6 show a first embodiment of the electromagnetically actuated reciprocating piston pump 1 according to the invention. The reciprocating piston pump 1 has a pump axis 10. In the context of the present invention, axial means in the direction of the pump axis 10.

[0066] Figure 2 shows an isometric view of the reciprocating piston pump 1 with a pump housing 2 and a pump cover 3. A plug 4 is installed on the pump cover 3.

[0067] The pump housing 2 has several housing webs 29 on its outer circumference. Pump housings 2 with housing webs 29 are accommodated in a housing cavity (not shown) of a gear housing and held centered therein. The pump housing 2 has parallel channels that form flow channels on the inlet and outlet sides. The pump inlet 5 is located on the suction side 7, while the pump outlet 6 is located on the pressure side 8.

[0068] While the inlet-side channels are formed between the pump housing 2 and the housing webs 29, the outlet channels 9 are closed radially outward, toward the pump housing 2. This ensures effective cooling of the annular coils 12', 12" installed in the pump housing 2 from the outside by the surrounding fluid. A corresponding design of the housing webs 29 enables a defined flow around the annular coils 12', 12".

[0069] There is a pump housing 2 through which oil flows, with wet-running lifting magnets and oil-damped movement of a pump piston.

[0070] In addition to the axial flow illustrated, other designs are conceivable, for example, allowing for a spiral or meandering flow. This ensures effective heat dissipation through convective heat dissipation, while also allowing the implementation of additional functions, such as a coil heating function for low-temperature operation or the possibility of sufficiently precise fluid temperature measurement via resistance measurement on the coil winding.

[0071] In addition, plastic injection-molded components made of, for example, PPS + 50% GF can be used for the housing components, which enables a cost-efficient pump design.

[0072] The first and second outlet channels 9', 9" are combined in the pump outlet 6. The fluid volume arranged on the pressure side 8 in the area of ​​the pump outlet 6 acts as a damping volume to smooth the inherent flow pulsations.

[0073] On the inlet side, the fluid is guided via axially and radially introduced recesses arranged on the suction side 7 as pump inlet 5 in the pump housing 2 to a first and a second inlet valve 20', 20" of the reciprocating piston pump 1. As can be seen from the sectional views in Figures 4, 5, 6, 9 and 10, the first inlet valve 20' is arranged on the left side of the pump piston 19, viewed in the axial direction of the reciprocating piston pump 1, and the second inlet valve 20" is arranged on the right side of the pump piston 19. This realizes a double-acting operating principle with the pump piston pressurized from both sides, as well as defined flow around and convective heat dissipation of the electromagnetic active parts of the pump, both on the suction and pressure sides, radially inward and radially outward, via the operating medium.

[0074] The electromagnetic active components of the reciprocating piston pump 1 include: two pole cores, two pole disks, two shells, two yoke disks, and the two toroidal coils. The arrangement of these components is described in more detail below using the sectional views. The electromagnetic active components are fixed to the housing and enclosed by the pump housing 2, which is partially open to the outside. This ensures effective heat dissipation through the surrounding fluid.

[0075] This can be additionally supported by the use of a guide device which guides the fluid in a defined radial and axial direction around the outer surface of the pump housing 2 and subsequently to the first and second inlet valves 20', 20". The guide device can be designed as a separate, single-part or multi-part insert or by a special design of the housing webs 29. This means that the housing webs 29 do not necessarily have to run parallel to the pump axis 10, but can be designed in such a way that meandering or thread-shaped flow channels are formed between the pump housing 2 with the housing webs 29 and the receiving cavity in the gear housing.

[0076] Figure 3 shows a top view of the pump housing 2 (view A in Figure 2).

[0077] Figure 4 shows a longitudinal section - section plane AA in Figure 3 - through the electromagnetically actuated reciprocating piston pump 1 according to the invention.

[0078] The reciprocating piston pump 1 is designed with a double coil assembly 25 and has two toroidal coils fixed to the housing, namely a first and a second toroidal coil 12', 12", which are arranged on a common coil body 11. The other soft iron components (electromagnetic active parts) required for the respective electromagnetic circuit, pole core, pole disc, casing, and yoke disc, are identical for the first and second toroidal coils 12', 12", and are arranged axially symmetrically to the axis SA (Fig. 9) relative to the coil body 11.

[0079] Accordingly, the first toroidal coil 12' is assigned a first pole core 14', a first pole disk 15', a first casing 16', and a first yoke disk 17'. The second toroidal coil 12" is assigned a second pole core 14", a second pole disk 15", a second casing 16", and a second yoke disk 17". Figure 5 shows a further longitudinal section - section plane BB in Figure 3 - through the reciprocating piston pump 1 along the pump axis 10. The arrows symbolize the suction and pressure side flow path through the reciprocating piston pump 1. Fluid is sucked in through the two inlet valves, namely the first inlet valve 20' and the second inlet valve 20". The arrows show the inflow of the fluid up to the suction side 7. The flow of the fluid runs through the first and second inlet valves 20' and 20" into the pump chamber, more precisely into the first displacement chamber 24' and the second displacement chamber 24".Via the first outlet valve 21' and the second outlet valve 21" and through the coil body 11, the fluid flows on the pressure side via the first outlet channel 9' and the second outlet channel 9" to the pump outlet 6 on the pressure side 8.

[0080] Figure 6 shows a detailed sectional view of the longitudinal section BB shown in Figure 5. In this illustration, the pump piston 19 is displaced axially to the right, and the second displacement chamber 24" is reduced in volume, thus compressing the fluid therein ("top dead center"). The first displacement chamber 24', on the other hand, shows its maximum capacity ("bottom dead center").

[0081] The pump piston 19 is guided by a two-part guide sleeve consisting of two short bearing bushes, namely a first bearing bush 23' and a second bearing bush 23", made of bearing bronze or other plain bearing materials. This design of the split bearing bush and division into the first and second bearing bushes 23', 23", eliminates the need for a continuous, thin-walled guide sleeve. In addition, the two bearing bushes, namely the first bearing bush 23' and the second bearing bush 23", can be designed with greater wall thicknesses, for example, in the range of 1.5 to 3 mm. The functionally required radial gap S for magnetic insulation between the first yoke disc 17' or the second yoke disc 17" and the pump piston 19 can nevertheless be kept small (diametrical play is preferably in the range 0.03 mm - 0.06 mm), which has a beneficial effect on the magnetic circuit. A cost-intensive thin-walled stainless steel sleeve, iAA drawn stainless steel or brass tube with, to minimize electromagnetic losses, the smallest possible wall thickness - generally less than 0.4mm, ideally 0.2mm - can be omitted.

[0082] Figures 7-10 show a further embodiment of the electromagnetically actuated reciprocating piston pump 1 according to the invention with an integrated valve 30 for controlling two partial volume flows, a first partial volume flow QA and a second partial volume flow QB. The specific design of the reciprocating piston pump 1 allows for the optional use of the valve 30. All other components remain unaffected and have already been described in relation to Figures 2 to 6.

[0083] The valve 30 has a valve housing 31 and a valve cover 32.

[0084] Figure 8 shows in a front view the arrangement of the valve 30 on the reciprocating piston pump 1 .

[0085] Figure 9 shows the structure of the valve 30 in a sectional view along the pump axis 10. Viewed radially within the valve housing 31, a cylindrical valve piston 33 is arranged. Between the valve housing 31 and the valve piston, on the outer surface of the valve piston 33, there is a first valve spring 34. This is spiral-shaped. The first valve spring 34 is a thermosensitive spring. Alternatively, a wax element can be used. Within the valve piston 33 there is a second valve spring 35 which acts as a return spring for the valve 30. A first outlet 36 is located in the radial direction on a flange with which the valve 30 is connected to the pump housing 2. A second outlet 37 is arranged axially parallel to the pump axis 10 on the front side of the valve housing 31.

[0086] Figure 10 shows the reciprocating piston pump in a view rotated about its pump axis 10, so that the first outlet 36 can be seen in the top view of the figure. In Figure 11, a section along the plane C - C in Figure 9 was chosen, which lies exactly centrally along the axis SA between the first toroidal coil 12' and the second toroidal coil 12". The housing webs 29 can be seen, which also encompass the first outlet channel 9' and the second outlet channel 9". The pump piston 19 can be seen radially inside the coil body 11. The first and second toroidal coils 12', 12" are contacted via a first groove 28' for a wire feedthrough and a second groove 28" for the wire feedthrough.

[0087] Figure 12 shows a section approximately along the valve seat of the first outlet valve 21'. The first annular coil 12' can be seen radially outside the first bearing bush 23'. The pump piston 19 and the first outlet valve 21' are arranged within the first bearing bush 23'.

[0088] Figures 13-15 show different views of the double coil assembly 25, consisting of the common coil body 11 and integrated yoke discs, namely the first yoke disc 17' and the second yoke disc 17". The windings of the two toroidal coils 12', 12" arranged on the coil body are not shown.

[0089] The double coil assembly 25 is preferably designed as a plastic injection-molded component with overmolded first and second yoke disks 17', 17". The first and second yoke disks 17', 17" are inserted into an injection molding tool as inserts and overmolded with the coil body 11. The clearances functionally required for the oil and wire guide, in particular the centrally located annular groove 27, the recesses for the pump outlet with a first recess 26' and a second recess 26", as well as the grooves with the first groove for the wire feedthrough 28' and the second groove for the wire feedthrough 28", can thus be integrated cost-effectively into the plastic injection-molded component.

[0090] Figure 15 shows a sectional view of the double coil assembly 25 as a plastic injection-molded component with the two overmolded yoke discs, the first yoke disc 17' and the second yoke disc 17", as well as the centrally radially encircling annular groove 27.

[0091] Figure 16 shows an isometric view of an exemplary embodiment of the first yoke disc 17' with integrated grooves 28', 28" and openings 38 required for overmolding, which, for cost reasons, are preferably manufactured as a deep-drawn stamped part with a calibrated inner diameter. The openings 38 are designed as axially extending bores.

[0092] Figure 17 shows a schematic representation of the connection of the two electromagnetic coils, namely the first toroidal coil 12' and the second toroidal coil 12" of the reciprocating piston pump 1 according to the invention. A two-pole electrical connection 40 is connected to the first coil 12' and the second coil 12" via a first freewheeling diode 39' and a second freewheeling diode 39".

[0093] Figure 18 shows a further schematic representation of the connection of the first toroidal coil 12' and the second toroidal coil 12". Voltage is applied to the first toroidal coil 12' and the second toroidal coil 12" via a three-pole connection 41.

[0094] Figures 19a and 19b show two different methods for controlling the pump, which differ primarily in the achievable dynamics (maximum stroke frequency) and the electrical power consumption (energy efficiency).

[0095] The coordinate systems shown are a current i / time t diagram. The current profile is sinusoidal or stepped with a period T 43 and a positive and a negative half-wave 44', 44". In Fig. 19a, a sinusoidal current profile 44' is shown. In Fig. 19b, a stepped profile 45' with several current steps i1, i2, i3.

[0096] The two control methods differ particularly in terms of the achievable stroke frequency and energy efficiency (the electrical energy absorbed by the coil corresponds to the hatched area).

[0097] Figures 20 - 27 show a further embodiment of an embodiment of a reciprocating piston pump T according to the invention. This differs from the previously described embodiments in that a double coil assembly 25 is not formed by a common coil body 11 with the first and second toroidal coils 12' and 12", but rather by two individual coil assemblies 25' which are accommodated in the pump housing 2.

[0098] Only the differences in Figures 20-27 compared to the previously described embodiments of the reciprocating piston pump 1 according to the invention are described. Identical components have the same reference numerals.

[0099] Figures 20 and 21 show the further embodiment of the reciprocating piston pump T according to the invention in two different longitudinal sections (rotated by 90 degrees)

[0100] The reciprocating piston pump T is designed with two individual coil assemblies 25'. The two individual coil assemblies each have a toroidal coil, namely the first toroidal coil 12' and the second toroidal coil 12", which are each arranged separately on a coil former. This means that the first toroidal coil 12' is arranged on a first coil former 1T and the second toroidal coil 12" is arranged on a second coil former 11". The other soft iron components (electromagnetic active parts) required for the respective electromagnetic circuit, pole core, pole disk, casing, and yoke disk, are identical for the first and second toroidal coils 12', 12".

[0101] The two individual coil assemblies 25' in Figures 20 and 21 are preferably constructed symmetrically (identical parts). For the sake of simplicity, only one of the two individual coil assemblies 25' is shown and described below with reference to Figures 22-27.

[0102] The two pre-assembled individual coil assemblies 25', shown in Figures 24, 25, and 27, are installed symmetrically in the reciprocating piston pump 1' according to the invention, thus enabling cost-effective production. Additional components, such as spacer rings for positioning the coil assembly, can be omitted.

[0103] Figure 22 shows an isometric view of the first coil former 11' with the integrated first yoke disc 17'. The first coil former 11' is preferably designed as a plastic injection-molded component. It is possible to design the first yoke disc 17' as an insert and to overmold it with the first coil former 11' during the injection molding process. However, a multi-part design of the coil former and the yoke disc is also possible.

[0104] Figure 22 further shows the formation of radially extending recesses 26', 26".

[0105] Figure 23 shows an end view (view A in Figure 22) of the first coil former 11' with the integrated first yoke disc 17'. The radially extending recesses 26', 26" as well as the grooves for the wire feedthroughs 28 are visible.

[0106] From the sectional view of Figure 21, it can be seen that the two joined individual coil assemblies 25' form a circumferential annular groove 22 centrally in the area of ​​the opposite first and second yoke discs 17', 17". The collar forming the circumferential annular groove 22 and the radially extending recesses 26', 26" enable advantageous oil guidance and flow through the reciprocating piston pump 1' from radially inside to radially outside.

[0107] Figure 24 shows an isometric view of an assembly of a single coil assembly 25' of the embodiment of the reciprocating piston pump 1' shown in Figures 20 and 21.

[0108] Figure 25 shows an end view of the assembly of the single coil assembly 25'.

[0109] Figure 26 shows a sectional view of the coil former 11' shown in Figures 22 and 23 with integrated yoke disc 17'.

[0110] Figure 27 shows a sectional view of the assembly of the single coil assembly 25' with first coil body 11', first yoke disc 17', first shell 16', first pole disc 15', first pole core 14' and first inlet valve 20'.

[0111] Figure 28 shows a detailed section of the sliding surfaces between the pump piston 19 and the yoke discs 17', 17". In this embodiment, the pump piston 19 is guided axially displaceably directly in the yoke discs 17', 17" without the interposition of a two-part guide sleeve. The axial displaceability is indicated by the double arrow.

[0112] The pump piston 19 and the yoke disks 17', 17" are made of a material with good magnetic conductivity. This material has a high relative permeability. Examples of materials used include iron (Fe), ferrosilicon (FeSi), or free-cutting steel (11 SMn30). The pump piston 19 is provided with a magnetically insulating coating 19b on its outer surface 19a. This coating 19b also exhibits high wear resistance and good sliding properties. Teflon or a chromium nitride coating is advantageously used as the material for the coating. The coating has a layer thickness of 25 to 100 μm in particular. During an axial movement of the pump piston 19, the pump piston 19 slides by means of the coating 19b on its outer surface 19a on the inner surfaces 17a', 17a" of the first and second yoke disks 17', 17".

[0113] As an alternative to this embodiment, the coating 19b can also be applied to the radially opposite side of the guide, namely to the inner circumferential surfaces 17a' and 17a" of the yoke discs.

[0114] In an alternative embodiment (not shown), the pump piston 19 can also be guided directly in the coil body, which is made of plastic, e.g., PPS + 50 GF / MD. In this embodiment, coating the outer surface of the piston with a material with magnetically insulating properties is not necessary.

[0115] Figure 29 shows a detailed section of the sliding surfaces according to the first embodiment, in which the pump piston 19 is guided axially displaceably in the two-part guide sleeve. The two-part guide sleeve is designed as a first and second bearing bush 23' and 23". The axial displaceability is indicated by the double arrow.

[0116] The pump piston 19 and the first and second bearing bushes 23', 23" are made of a material with good magnetic conductivity. This material has a high relative permeability. Examples of materials used include iron (Fe), ferrosilicon (FeSi), or free-cutting steel (11SMn30).

[0117] The first and second bearing bushes 23', 23" are preferably thick-walled, with a wall thickness of 1-3 mm. The pump piston 19 is provided with a magnetically insulating coating 19b on its outer surface 19a. This coating 19b also has high wear resistance and good sliding properties. Teflon is advantageously used as the material for the coating. The coating has a layer thickness of 25 to 100 μm in particular.

[0118] During an axial movement of the pump piston 19, the pump piston 19 slides by means of the coating 19b on its outer surface 19a on the inner surfaces 23a', 23a" of the first and second bearing bush 23', 23".

[0119] As an alternative to this embodiment, the coating 19b can also be applied to the radially opposite side of the guide, namely to the inner circumferential surfaces 23a' and 23a" of the yoke discs.

[0120] The design variants previously described for Figures 28 and 29 have the advantage that the iron content in the magnetic circuit is increased, which leads to a higher power density and minimizes eddy current losses.

[0121] As a further alternative embodiment, the following configuration is also possible. The pump piston 19 is guided axially displaceably in the two-part guide sleeve. The two-part guide sleeve is designed as a first and second bearing bush 23' and 23".

[0122] The pump piston 19 is made of a material with good magnetic conductivity. This material has a high relative permeability. Examples of materials used include iron (Fe), ferrosilicon (FeSi), or free-cutting steel (11 SMn30).

[0123] The two-part guide sleeve in the design of a first and second bearing bush 23', 23" are made of a magnetically insulating material which has a low relative permeability (p r ~ 1 ). Examples of materials used include aluminum (AI), (EN AW 6062), stainless steel, or brass. The pump piston 19 is provided with a magnetically insulating coating 19b on its outer surface 19a. This coating 19b also exhibits high wear resistance and good sliding properties. Teflon is advantageously used as the material for the coating. The coating has a layer thickness of 25 to 100 μm.

[0124] During an axial movement of the pump piston 19, the pump piston 19 slides by means of the coating 19b on its outer surface 19a on the inner surfaces 23a', 23a" of the first and second bearing bush 23', 23".

[0125] As an alternative to this embodiment, the coating 19b can also be applied to the radially opposite side of the guide, namely to the inner circumferential surfaces 23a' and 23a" of the yoke discs.

[0126] Reference symbol

[0127] I , 1 ' reciprocating piston pump

[0128] 2 pump housings

[0129] 3 pump covers

[0130] 4 plugs, electrical connection

[0131] 5 Pump inlet

[0132] 6 Pump outlet

[0133] 7 Suction side

[0134] 8 printed pages

[0135] 9', 9" first exhaust port, second exhaust port

[0136] 10 Pump axis

[0137] II , 11 ', 11“ coil former, first coil former, second coil former

[0138] 12', 12" first toroidal coil, second toroidal coil

[0139] 14', 14“ first pole core, second pole core

[0140] 15', 15“ first pole disc, second pole disc

[0141] 16', 16" first coat, second coat

[0142] 17', 17“ first yoke disc, second yoke disc

[0143] 18', 18" first elastic element, second elastic element

[0144] 19 pump pistons

[0145] 19a outer surface

[0146] 20', 20" first inlet valve, second inlet valve

[0147] 21 21“ first exhaust valve, second exhaust valve

[0148] 22 ring groove

[0149] 23', 23“ first bearing bush, second bearing bush

[0150] 23a', 23a“ inner lateral surfaces

[0151] 24, 24', 24" displacement chamber, first displacement chamber, second displacement chamber

[0152] 25 Double coil assembly

[0153] 25' single coil assembly 26', 26" first recess, second recess

[0154] 27 Ring groove

[0155] 28', 28“ first groove for wire feedthrough, second groove for wire feedthrough

[0156] 29 housing bars

[0157] 30 valve

[0158] 31 valve housing

[0159] 32 valve covers

[0160] 33 valve pistons

[0161] 34 First valve spring,

[0162] 35 Second valve spring,

[0163] 36 First outlet

[0164] 37 Second outlet

[0165] 38 Breakthrough

[0166] 39', 39“ first freewheeling diode, second freewheeling diode

[0167] 40 Electrical connection (2-pin)

[0168] 41 Electrical connection (3-pin)

[0169] 42 working strokes

[0170] 43 Period duration

[0171] 44 first current profile

[0172] 44' first current profile (positive half-wave)

[0173] 44" first current profile (negative half-wave)

[0174] 45 second current profile

[0175] 45' second current profile (positive signal)

[0176] 45" second current profile (negative signal)

[0177] QA First partial volume flow

[0178] QB Second partial volume flow

Claims

Claims 1. Reciprocating piston pump (1, 1') with a pump housing (2) through which fluid flows and a pump axis (10), and an axially movable pump piston (19) through which fluid flows, arranged coaxially to two housing-fixed toroidal coils, namely a first toroidal coil (12') and a second toroidal coil (12"), wherein the reciprocating piston pump (1) has two inlet valves, namely a first inlet valve (20') and a second inlet valve (20"), and two outlet valves, namely a first outlet valve (21') and a second outlet valve (21"), wherein the first inlet valve (20') and the first outlet valve (21') are arranged concentrically to the pump axis (10) radially inside the first toroidal coil (12'), and the second inlet valve (20') and the second outlet valve (21') are arranged concentrically to the pump axis (10) radially inside the second toroidal coil (12"), and the pump piston (19) in a two-part guide sleeve or directly in the pump housing (2) arranged yoke discs (17',17") is guided in a two-part displacement chamber.

2. Reciprocating piston pump (1, 1') according to claim 1, characterized in that the pump piston (19) integrates the function of a movable armature and a delivery piston.

3. Reciprocating piston pump (1, 1') according to claim 1 or 2, characterized in that radially inside the pump housing (2) the first toroidal coil (12') and the second toroidal coil (12") are arranged on a common coil body (11) forming a double coil assembly (25).

4. Reciprocating piston pump (1, 1') according to claim 1 or 2, characterized in that two individual coil assemblies (25') are arranged radially inside the pump housing (2), each individual coil assembly having a toroidal coil and a separate coil body.

5. Reciprocating piston pump (1 , T) according to claim 3 or 4, characterized in that the double coil assembly (25) or the single coil assemblies (25') of the Further, as electromagnetic active parts, a first yoke disc (17') assigned to the first toroidal coil (12') and a second yoke disc (17") assigned to the second toroidal coil (12").

6. Reciprocating piston pump (1, T) according to claim 5, characterized in that the first and second yoke discs (17', 17") are made of a material with good magnetic conductivity and a high relative permeability, the material preferably being iron (Fe), ferrosilicon (FeSi) or a free-cutting steel (11 SMn30).

7. Reciprocating piston pump (1, T) according to claim 5, characterized in that the first and second yoke discs (17', 17") are connected to the common coil body (11) or the associated separate coil bodies (11', 11") in an injection molding process by overmolding.

8. Reciprocating piston pump (1) according to claim 5, characterized in that the first and second yoke discs (17', 17") and the common coil body (11) or the associated separate coil bodies (11', 11") and the yoke discs (11', 11') are designed in several parts.

9. Reciprocating piston pump (1, T) according to one of the preceding claims, characterized in that a first pole core (14'), a first pole disc (15'), a first jacket (16') are assigned to the first toroidal coil (12') as further housing-fixed electromagnetic active parts, and a second pole core (14'), a second pole disc (15'), a second jacket (16') are assigned to the second toroidal coil (12").

10. Reciprocating piston pump (1, T) according to one of the preceding claims, characterized in that the first and the second toroidal coil (12', 12") with associated electromagnetic active parts, in particular the first and second yoke discs (17', 17") are designed identically and are arranged axially symmetrically on the coil body (11) or that the individual coil assemblies (25') are constructed symmetrically.

11. Reciprocating piston pump (1, T) according to one of the preceding claims, characterized in that the pump piston (19) is made of a material with good magnetic conductivity and a high relative permeability, the material preferably being iron (Fe), ferrosilicon (FeSi) or a free-cutting steel (11 SMn30).

12. Reciprocating piston pump (1, T) according to claim 1, characterized in that the two-part guide sleeve consists of a first bearing bush (23') and a second bearing bush (23"), wherein the first and second bearing bush (23', 23") are made of a material with good magnetic conductivity and a high relative permeability, wherein the material is preferably iron (Fe), ferrosilicon (FeSi) or a free-cutting steel (11 SMn30), and wherein further advantageously the bearing bushes (23', 23") are thick-walled with a wall thickness of 1 - 3 mm.

13. Reciprocating piston pump (1, T) according to claim 1, characterized in that the two-part guide sleeve consists of a first bearing bush (23') and a second bearing bush (23"), wherein the first and second bearing bush (23', 23") are made of a magnetically insulating material with low relative permeability (p r~ 1 ), the material preferably being aluminium (AI), (EN AW 6062), stainless steel or brass.

14. Reciprocating piston pump (1, T) according to one of the preceding claims, characterized in that the pump piston (19) on its outer surface (19a) or the first and second bearing bush (23', 23") on their inner surfaces (23a', 23a") are designed with a magnetically insulating coating (19b), preferably Teflon or chromium nitride, wherein the coating further advantageously comprises a layer thickness of 20 to 100 pm.

15. Reciprocating piston pump (1, 1') according to one of the preceding claims, characterized in that a valve (30) is arranged on the outlet side of the reciprocating piston pump (1, 1 ') and provides two paths for the volume flow of the fluid.

16. Reciprocating piston pump (1, T) according to one of the preceding claims, characterized in that the inlet-side flow on the suction side is guided by means of a guide device which guides the fluid in a defined radial and axial direction around the outer surface of the pump housing (2) and subsequently to the first and second inlet valve (20', 20").

17. Method for controlling a reciprocating piston pump (1, T) according to the preceding claims, characterized in that the control of the pump piston (19) is carried out via current profiles (44, 45) with positive and negative current pulses.

18. Method for controlling a reciprocating piston pump (1, T) according to claim 17, characterized in that hydraulic end position damping is carried out by a path-controlled orifice geometry on the pump piston (19).

19. Method for controlling a reciprocating piston pump (1, T) according to claim 17, characterized in that electromagnetic damping is carried out by a current profile (44, 45) of the current supply to the first and second toroidal coils (12', 12").

20. Method for controlling a reciprocating piston pump (1, T) according to claim 17, characterized in that a short-term overload operation is possible.

21. Method for controlling a reciprocating piston pump (1, T) according to claim 17, characterized in that an active distribution of the flow rate takes place via a thermosensitive element.

22. Method for controlling a reciprocating piston pump (1, T) according to claim 17, characterized in that a coil heater is used for improved low-temperature starting behavior.

23. Method for controlling a reciprocating piston pump (1, 1') according to claim 17, characterized in that a fluid sump temperature measurement is carried out via a voltage drop at the first toroidal coil (12') and / or the second toroidal coil (12").

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