Fluid transfer pump

Abstract

Fluid conveying pump (1) comprising: - a pump chamber (2), - a displacement assembly (3) arranged in the pump chamber (2) with a shaft (6) via which the displacement assembly (3) can be driven, the shaft (6) being mounted in a shaft chamber (7), - a first connecting line (4) connected for fluid communication to a first region (2a) of the pump chamber (2), - a second connecting line (5) separate from the first connecting line (4) and connected for fluid communication to a second region (2b) of the pump chamber (2), characterized in that - a control unit (12) for connecting the wave chamber (7) to that connecting line of the first connecting line (4) and the second connecting line (5) which functions as a supply line for supplying fluid to the pump chamber (2), or for connecting the wave chamber (7) to that area of ​​the first area (2a) and the second area (2b) which is a low-pressure area of ​​the pump chamber (2), wherein the control unit (12) has a first valve (8) arranged between the wave chamber (7) and the first connecting line (4) or the first area (2a), which, when an overpressure prevails in the wave chamber (7) compared to the first connecting line (4) or the first area (2a),which releases the connection between the wave chamber (7) and the first connecting line (4) or the first region (2a) in the event of overpressure in the wave chamber (7) relative to the first connecting line (4) or the first region (2a), and which has a second valve (9) arranged between the wave chamber (7) and the second connecting line (5) or the second region (2b), which, when overpressure prevails in the wave chamber (7) relative to the second connecting line (5) or the second region (2b), releases the connection between the wave chamber (7) and the second connecting line (5) or the second region (2b) in the event of overpressure in the wave chamber (7) relative to the second connecting line (5) or the second region (2b), and wherein the displacement assembly (3) is configured to pump fluid in a first pumping direction from the first region (2a) into the second region (2b) and in a second pumping direction from the second region (2b) into the first region (2a).

Description

[0001] The present invention relates to a fluid delivery pump. The fluid delivery pump, in particular, has a pressure relief device to relieve the load on a drive of the fluid delivery pump.

[0002] Fluid transfer pumps are known from the prior art. Such pumps are used to transfer fluids, in particular hydraulic fluids or oils. For this purpose, a displacement assembly is mounted within a pump chamber. This displacement assembly is driven by a shaft. If the fluid transfer pump is operated reversibly, i.e. the pumping direction is not predetermined, sealing the fluid transfer pump is more difficult. If the fluid transfer pump is designed to generate high pressures, the fluid often enters a drive unit of the fluid transfer pump, which is then exposed to high fluid pressures. The fluid transfer pump must therefore be provided with thick walls in order to absorb the high forces and high impulse forces that occur. This makes the fluid transfer pump very heavy. Furthermore, the use of radial shaft seals is not possible in conventional fluid transfer pumps due to the reversible operation and the high pressures that occur.

[0003] AT 500 629 A1 discloses a gear pump with variable delivery volume with two meshing externally toothed gears which are rotatably mounted in a delivery chamber of a pump housing.

[0004] US 2003 / 0 202 887 A1 discloses a motor pump operating with an internal combustion engine, as a booster pump, or in a stand-alone device, having an internal vent for improved pump and motor durability. The pump is operably and sealably connected to a motor and is suitable for connection to a fluid source and a drain means. An internal vent is positioned between an armature stem or bore along an inlet port, reducing pressure in the area of ​​the seal. Alternatively, a valve is positioned between the inlet and outlet ports to selectively allow pumped fluid to pass between the inlet and outlet ports when the outlet port is flow-restricted.

[0005] It is an object of the present invention to provide a fluid conveying pump which, with simple and cost-effective manufacture and assembly, has a safe and reliable reduction of the pressure acting on the drive unit.

[0006] The problem is solved by the features of the independent claim. The subclaims contain preferred developments of the invention.

[0007] The object is thus achieved in particular by a fluid delivery pump which has a pump chamber and a displacement assembly arranged in the pump chamber. The displacement assembly can be driven via a shaft. In particular, the displacement assembly is a gear pump device. The pump chamber has a first region and a second region different from the first region. Depending on the pumping direction, the displacement assembly is designed to pump fluid either from the first region to the second region or from the second region to the first region. Furthermore, the fluid delivery pump has a first connecting line and a second connecting line separate from the first connecting line. Both the first connecting line and the second connecting line serve for fluid communication with the pump chamber.The first connecting line serves for fluid communication with the first region of the pump chamber and the second connecting line serves for fluid communication with the second region of the pump chamber. It is provided that the first connecting line and the second connecting line serve, depending on the pumping direction, either as a supply line for supplying fluid to the pump chamber or as a discharge line for discharging fluid from the pump chamber. The first connecting line and the second connecting line therefore advantageously open into the pump chamber on opposite sides of the shaft, i.e. the first region and the second region are arranged on opposite sides of the shaft. The shaft is mounted in a shaft chamber, wherein the shaft chamber is connected to the pump chamber for fluid communication. It is provided that the shaft chamber is connected to the first connecting line and the second connecting line for fluid transmission.Alternatively or additionally, the wave chamber is connected to the first region and the second region of the pump chamber. A fluid pressure in the first connecting line and in the first region is identical, just as a fluid pressure in the second connecting line and in the second region is identical. It is therefore irrelevant whether the respective region of the pump chamber or the associated connecting line is connected to the wave chamber. In any case, a pressure acting within the wave chamber can be reduced in the first connecting line and / or the second connecting line and / or the first region and / or the second region. It is provided that the fluid delivery pump has a control unit. The control unit serves to connect the wave chamber to that connecting line of the first connecting line and the second connecting line which functions as a supply line for supplying fluid to the pump chamber.Alternatively or additionally, the control unit serves to connect the wave chamber with that area of ​​the first area and second area which is a low-pressure area of ​​the pump chamber. As already described, either the first connecting line serves as the supply line and the second connecting line as the discharge line, or the first connecting line serves as the discharge line and the second connecting line as the supply line. Likewise, the first area or the second area can function as the low-pressure area, depending on which area is currently connected to the supply line. By definition, the pressure in the supply line is lower than in the discharge line. The control unit is therefore designed to always connect the wave chamber to the supply line.The control unit thus selectively connects the shaft chamber either to the first connecting line or to the second connecting line, depending on which of these connecting lines serves as the supply line in a current pumping direction. The shaft chamber is thus always kept at the pressure level prevailing in the supply line. This reduces the fluid pressure within the shaft chamber. This relieves the shaft chamber and a drive unit of the fluid feed pump. In particular, no compensation tank is required for this. Rather, the fluid feed pump can form a closed system, whereby pressure equalization is nevertheless possible via the said connection between the shaft chamber and the first connecting line and the second connecting line, wherein the control unit has a first valve, in particular a pressure relief valve or dual-pressure valve, and a second valve, in particular a pressure relief valve or dual-pressure valve.The first valve is arranged between the wave chamber and the first connecting line or the first area. The second valve is arranged between the wave chamber and the second connecting line or the second area. The first valve is designed to open a connection between the wave chamber and the first connecting line or the first area when there is an overpressure in the wave chamber compared to the first connecting line or the first area. The same is designed to open a connection between the wave chamber and the second connecting line or the second area when there is an overpressure in the wave chamber compared to the second connecting line or the second area. The displacer assembly applies a pressure to the wave chamber that is greater than the pressure of the supplied fluid, but at the same time less than the pressure of the discharged fluid.There is therefore always an overpressure compared to the supply line or the first area, so that the first valve only opens the connection when the first connecting line is used as a supply line or the first area as a low-pressure area, while the connection between the second connecting line and the wave chamber is similarly only opened by the second valve when the second connecting line is used as a supply line or the second area as a high-pressure area. This ensures that the wave chamber is always connected to the lower-pressure connecting line from the first connecting line and second connecting line or to the lower-pressure connecting line from the first area and second area. The displacer assembly is set up to pump fluid in a first pumping direction from the first area into the second area. The displacer assembly is set up to pump fluid in a second pumping direction from the second area into the first area.Consequently, the displacer assembly is configured to convey a fluid in the first direction and in the second direction.

[0008] The fluid delivery pump advantageously has at least one pressure equalization groove that extends parallel to the shaft through the displacer assembly. The pressure equalization groove can in particular be introduced into the shaft or into an element of the displacer assembly that is directly coupled to the shaft, for example a gear. The pressure equalization groove also enables self-centering of the displacer assembly within the pump chamber, since the same fluid pressure prevails axially on both sides of the displacer assembly. In particular, it is provided for this purpose that the shaft chamber extends axially on both sides of the displacer assembly, with the same fluid pressure acting in all areas of the shaft chamber due to the pressure equalization groove. In particular, the pressure relief described above creates a pressure imbalance within the shaft chamber, which is compensated for by the pressure equalization groove.The displacement assembly, in particular the gears, can thus be axially centered in the pump chamber so that there is no contact with other components. Radial centering is achieved primarily via bearings, preferably needle bearings, of the shaft. This leads to low-wear operation of the fluid transfer pump and thus a long service life. In addition, the fluid transfer pump is simple and inexpensive to construct. In particular, the components of the fluid transfer pump can be manufactured inexpensively, lightly, small, dynamically, and efficiently. In addition, a radial shaft seal can be integrated under suitable pressure conditions, something that was not reasonably possible with the prior art. In principle, pressure loads and impulse loads on pressurized surfaces within the drive unit are greatly reduced. This generally ensures a longer service life for the fluid transfer pump.

[0009] Finally, it is particularly advantageous that the first valve remains closed in the event of excess pressure in the first connecting line or the first area opposite the wave chamber and / or that the second valve remains closed in the event of excess pressure in the second connecting line or the second area opposite the wave chamber. This prevents the wave chamber from being pressurised through the connection between the first connecting line or first area and the wave chamber and / or the second connecting line or second area and the wave chamber. Rather, said connection between the first connecting line or first area and the wave chamber and the second connecting line and the second area and the wave chamber can therefore be used exclusively for pressure relief. The first valve is therefore particularly advantageously designed as a shuttle valve.The inlets of the shuttle valve are coupled to the wave chamber and the first connecting line or the first area. An outlet of the shuttle valve is also coupled to the first connecting line or the first area. Thus, a connection between the wave chamber and the first connecting line or the first area is only possible if there is an overpressure in the wave chamber compared to the first connecting line or the first area. If, on the other hand, there is an overpressure in the first connecting line or the first area compared to the wave chamber, the connection between the wave chamber and the first connecting line or the first area remains closed by the shuttle valve. The same configuration advantageously applies to the second valve. The second valve is also preferably designed as a shuttle valve, with the inlets of the shuttle valve being connected to the wave chamber and the second connecting line or the second area.The output of the shuttle valve is also coupled to the second connecting line or the second area. The shuttle valve is not preloaded or spring-loaded. This means that the shuttle valve remains in its current position if there is no pressure difference between the wave chamber and the first connecting line or first area, or the second connecting line or second area. A change in the switching state occurs automatically when the overpressure changes.

[0010] The wave chamber is advantageously connected to the first connecting line or the first region via a first throttle valve. Alternatively or additionally, the wave chamber is advantageously connected to the second connecting line or the second region via a second throttle valve. This makes it possible to dampen an equalization of the pressure within the wave chamber and the first connecting line or first region and / or second connecting line or second region. This in particular avoids or at least reduces pulse loads within the fluid feed pump. In the case of the previously described design of the valve as a shuttle valve, it is provided in particular that the throttle valve is coupled to the output of the shuttle valve.

[0011] The displacer assembly preferably applies a fluid pressure of between 70% and 30%, in particular between 60% and 40%, and more particularly 50%, of the output pressure generated by the displacer assembly to the wave chamber. The output pressure acts in the discharge line and thus either in the first connecting line or in the second connecting line. The fluid pressure prevailing in the wave chamber is thus greater than the fluid pressure in the supply line but less than the fluid pressure in the discharge line. By connecting the wave chamber and the first connecting line and / or the second connecting line, in particular in conjunction with the previously described control unit, it is ensured that the wave chamber is always coupled to the lower-pressure side of the first connecting line and the second connecting line for pressure relief.This is achieved by coupling the shaft chamber to the supply side of the fluid transfer pump in order to reduce the fluid pressure within the shaft chamber.

[0012] In a preferred embodiment, the fluid delivery pump has a drive unit. The drive unit serves to drive the shaft, thereby driving the displacement assembly. The drive unit is particularly advantageously an electric motor. In particular, the electric motor is hydraulically connected to the shaft chamber, so that the same fluid pressure that prevails in the shaft chamber acts on the electric motor. Due to the pressure relief described above, the shaft chamber is relieved of high pressures, so that a reduced pressure prevails in the shaft chamber. This also reduces the pressure acting on the drive unit, so that the drive unit is also relieved of high pressures. This extends the service life of the drive unit, in particular the electric motor. At the same time, the drive unit is simple and cost-effective to manufacture.

[0013] Particularly advantageously, the fluid feed pump comprises a housing element in which the shaft chamber is formed. Provision is made here for an additional chamber to be formed between the drive unit and the housing element. The shaft chamber is connected to the additional chamber for fluid transmission. Furthermore, the additional chamber is connected to the first region and / or the second region for fluid transmission. A connection for fluid transmission between the shaft chamber and the first region and / or the second region is thus enabled via the additional chamber. This in particular relieves the load on the drive unit since fluid pressure in the additional chamber can be at least partially reduced to the first region or the second region. In particular, fluid can enter the additional chamber through leakage.By connecting to the first area and / or second area, negative influences of this leakage, in particular resulting high pressures, on the drive unit can be reduced.

[0014] The first connecting line, the second connecting line, and the shaft chamber are arranged on the same axial side with respect to the shaft in order to open into the pump chamber. Thus, the pump chamber has all connections for the first connecting line, the second connecting line, and the shaft chamber on one axial side. This design enables the previously described fluid pressure to be applied in the shaft chamber, while at the same time making the first connecting line and the second connecting line simple and inexpensive to install. The pressure relief ensures that, despite this design, the fluid pressure within the shaft chamber is not higher than the fluid pressure in the supply line.

[0015] The shaft chamber is advantageously configured to adjoin the pump chamber to form a common free space. Thus, the shaft chamber and pump chamber form a common free space in which the shaft and the displacement assembly are arranged. The shaft and displacement assembly are, in particular, a common assembly. In particular, the shaft serves to drive a gear of the displacement assembly, which is advantageously configured as a gear displacement pump device.

[0016] Finally, it is preferably provided that the displacement assembly is a gear ring pump device. The gear ring pump device has a gear ring and a gear running eccentrically within the gear ring. In this way, a displacement assembly is realized by means of which fluid can be conveyed from the first connecting line or second connecting line acting as the supply line to the second connecting line or first connecting line acting as the discharge line.

[0017] The invention will now be described in more detail using an exemplary embodiment. In the following: Fig. 1 is a schematic illustration of a fluid conveying pump according to a first embodiment of the invention, Fig. 2 is a schematic fluid flow diagram of the fluid feed pump according to the first embodiment of the invention, Fig. 3 is a schematic illustration of the fluid conveying pump according to the first embodiment of the invention in operation with a first pumping direction, Fig. 4 is a schematic illustration of the fluid conveying pump according to the first embodiment of the invention in operation with a second pumping direction, Fig. 5 a schematic illustration of a fluid conveying pump according to a second embodiment of the invention Fig. 6 is a schematic illustration of the fluid conveying pump according to the second embodiment of the invention in operation with a first pumping direction, and Fig. 7 a schematic illustration of the fluid conveying pump according to the second embodiment of the invention in operation with a second pumping direction.

[0018] Fig. 1 schematically shows a fluid delivery pump 1 according to a first embodiment of the invention. The fluid delivery pump 1 comprises a pump chamber 2 in which a displacement assembly 3 is arranged. The displacement assembly 3 comprises a shaft 6. The displacement assembly 3 comprises a gear ring pump device in which a gear runs eccentrically in a gear ring. The shaft 6 serves in particular to drive the gear.

[0019] Furthermore, a first connecting line 4 and a second connecting line 5 are provided. The first connecting line 4 and the second connecting line 5 open into the pump chamber 2 on the same axial side with respect to the shaft 6. The first connecting line 4 and the second connecting line 5 are provided to open into the pump chamber 2 on opposite sides of the shaft 6. The displacer assembly 3 can thus pump fluid from the first connecting line 4 to the second connecting line 5 or vice versa. The first connecting line 4 and the second connecting line 5 can thus function optionally as a supply line or a discharge line. This depends on the pumping direction in which the displacer assembly 3 is operated.

[0020] On the same side of the pump chamber 2 on which the first connecting line 4 and the second connecting line 5 open into the pump chamber 2, there is a shaft chamber 7. The shaft chamber 7 is formed directly adjacent to the pump chamber 2, so that a common empty space is formed by the pump chamber 2 and the shaft chamber 7. The displacer assembly 3 is arranged in the pump chamber 2. The shaft 6 is rotatably mounted in the shaft chamber 7.

[0021] By designing the pump chamber 2 in this way, the displacement assembly 3, on the one hand, ensures that an output pump pressure prevails in the first connecting line 4 or the second connecting line 5, which functions as a discharge line. At the same time, a fluid pressure is introduced into the shaft chamber 7, which is between 70% and 30%, in particular between 60% and 40%, and more particularly 50%, of the output pump pressure. Depending on the output pump pressure, a high fluid pressure is thus present within the shaft chamber 7. In order to reduce this fluid pressure, a pressure equalization is implemented, which is controlled via a control unit 12. The control unit 12 is schematically shown in Fig. 2 shown as a circuit diagram. In Fig. 1 shows an exemplary representation of said control unit 12. Thus, it is provided that the wave chamber 7 is connected to the first connecting line 4 and the second connecting line 5 for fluid transmission. For this purpose, the control unit 12 comprises a first valve 8, which is arranged between the wave chamber 7 and the first connecting line 4. In addition, the control unit 12 comprises a second valve 9, which is arranged between the wave chamber 7 and the second connecting line 5. The first valve 8 allows the connection between the wave chamber 7 and the first connecting line 4 to be released only when there is an overpressure in the wave chamber 7 compared to the first connecting line 4. Likewise, the second valve 9 allows the connection between the wave chamber 7 and the second connecting line 5 to be released only when there is an overpressure between the wave chamber 7 and the second connecting line 5.Particularly advantageously, the first valve 8 and the second valve 9 are designed as shuttle valves. This ensures that the connection between the wave chamber 7 and the first connecting line 4 remains closed when there is excess pressure in the first connecting line 4. Likewise, the connection between the wave chamber 7 and the second connecting line 5 remains closed when there is excess pressure in the second connecting line 5. This ensures that the connections between the wave chamber 7 and the first connecting line 4 and the second connecting line 5 are used only to relieve pressure in the wave chamber 7.

[0022] Throttle valves are particularly advantageously provided in order to couple the wave chamber 7 to the first connecting line 4 and the second connecting line 5. In particular, a first throttle valve 10 is arranged between the wave chamber 7 and the first connecting line 4. A second throttle valve 11 is arranged between the wave chamber 7 and the second connecting line 5. It is particularly advantageous for the first throttle valve 10 to be coupled to an output of the first valve 8 designed as a shuttle valve. The inputs of the first valve 8 designed as a shuttle valve are coupled to the wave chamber 7 and the first connecting line 4. The same applies to the second valve 9 designed as a shuttle valve. Here, too, the inputs are preferably coupled to the wave chamber 7 and the second connecting line 5, while the second throttle valve 11 is coupled to the output.Thus, the use of shuttle valves ensures safe and reliable pressure relief control, reliably connecting only the first connecting line 4 or the second connecting line 5 with a lower fluid pressure than in the shaft chamber 7. In an alternative embodiment, the first throttle valve 10 and the second throttle valve 11 can be omitted.

[0023] The pressure relief provided by the control unit 12 only acts on one side of the shaft chamber 7. The shaft chamber 7 extends on both axial sides of the pump chamber 2 with respect to the shaft, with the control unit 12 being mounted on only one of these axial sides. To avoid only one-sided pressure relief, which would lead to an imbalance of the displacer assembly 3, pressure compensation grooves 16 are provided. These extend parallel to the shaft 6 through the entire pump chamber 2. This ensures that a uniform pressure prevails in the shaft chamber 7, which corresponds to the pressure of the fluid supplied to the fluid feed pump 1. The pressure relief grooves 14 are advantageously evenly distributed around the circumference of the shaft 6. In the exemplary embodiment shown, the pressure relief grooves 14 are incorporated into the gear of the displacer assembly 3 coupled to the shaft 6.

[0024] Through the pressure relief provided by the control unit 12, in addition to the shaft chamber 7, a drive unit 13 of the fluid feed pump 1 is also relieved. The drive unit 13 is, in particular, an electric motor acting on the shaft 6. Furthermore, it is provided that the drive unit 13 is hydraulically connected to the shaft chamber 7. Thus, the pressure relief of the shaft chamber 7 directly acts as a pressure relief of the drive unit 13, so that only the fluid pressure of the input fluid acts on the drive unit 13. Thus, the pressure relief prevents or at least reduces a load on the drive unit 13, in particular on the electric motor.

[0025] The Fig. 3 and Fig. 4 show an example of a fluid flow with different pumping directions of the fluid feed pump 1. Furthermore, Fig. 3 a first pumping direction, in which the first connecting line 4 functions as a supply line and the second connecting line 5 as a discharge line. In this case, a pressure level within the first connecting line 4 is lower than a pressure level within the wave chamber 7. This causes the first valve 8 to open and establish a connection between the wave chamber 7 and the first connecting line 4. At the same time, the second valve 9 remains closed due to the higher pressure within the second connecting line 5 compared to the wave chamber 7. This results in pressure relief to the first connecting line 4.

[0026] Fig. Figure 4 shows a case in which a reversed pumping direction prevails. The first connecting line 4 functions as the discharge line, while the second connecting line 5 functions as the supply line. Thus, the fluid pressure within the second connecting line 5 is lower than in the shaft chamber 7. This causes the second valve 9 to open, while the first valve 8 remains closed. This relieves pressure to the second connecting line 5.

[0027] The control unit 12 ensures safe and reliable pressure relief. The fluid delivery pump 1 can be designed as a closed system and requires no additional components, such as a compensation tank.

[0028] Fig. Figure 5 schematically shows a fluid feed pump 1 according to a second embodiment of the invention. The fluid feed pump 1 has basically the same structure as in the first embodiment, only the control unit 12 and the connections of the shaft chamber 7 are different. This will be explained below.

[0029] The pump chamber 2 has a first region 2a and a second region 2b. The first region 2a is connected to the first connecting line 4, and the second region 2b is connected to the second connecting line 5 for fluid communication. Thus, the same fluid pressure prevails in the first region 2a as in the first connecting line 4, and the same fluid pressure prevails in the second region 2b as in the second connecting line 5. The displacer assembly 3 serves to convey fluid from the first region 2a to the second region 2b or from the second region 2b to the first region 2a.

[0030] The shaft chamber 7, in which the shaft 6 is mounted, is connected to the first region 2a and the second region 2b for fluid communication. Since, as previously described, the same pressures prevail in these regions as in the associated connecting lines, a connection between the shaft chamber 7 and the first region 2a or the second region 2b produces the same effects as in the first embodiment. In particular, pressure relief thus occurs.

[0031] In Fig. 5, the drive unit 13 is schematically represented by its housing. The housing of the drive unit 13 interacts with a housing part 14 of the fluid feed pump 1, wherein the housing part 14 delimits the shaft chamber 7 and the pump chamber 2. In particular, the shaft chamber 7 extends through the housing part 14. The shaft chamber 7 is thus hydraulically connected to the drive unit 13. In particular, an additional chamber 15 is formed by the drive unit 13 and the housing element 14. The additional chamber 15 is connected to the shaft chamber 7 for fluid communication. Furthermore, the additional chamber 15 is connected to the first region 2a and the second region 2b of the pump chamber 2 for fluid communication. In particular, a control unit 12 is provided for this purpose, which is designed analogously to the first exemplary embodiment.

[0032] As in the first exemplary embodiment, a first valve 8 and a second valve 9 are present. The first valve 8 allows the connection between the additional chamber 15 and the first region 2a to be released when there is an overpressure in the additional chamber 15 compared to the first region 2a. Likewise, the second valve 9 allows the connection between the additional chamber 15 and the second region 2b to be released when there is an overpressure between the additional chamber 15 and the second region 2b. Since the additional chamber 15 is hydraulically connected to the shaft chamber 7 and the first region 2a is hydraulically connected to the first connecting line 4 and the second region 2b is hydraulically connected to the second connecting line 5, an operation analogous to the first exemplary embodiment is achieved. In particular, a control unit 12 is formed as in the first exemplary embodiment. Particularly advantageously, the first valve 8 and the second valve 9 are designed as a shuttle valve, analogous to the first exemplary embodiment.Throttle valves can also be present analogous to the first embodiment.

[0033] The Fig. 6 and Fig. 7 each show an example of a fluid flow with different pumping directions of the fluid feed pump 1. Fig. 6 a pumping direction in which the first connecting line 4 functions as a supply line and the second connecting line 5 as a discharge line. In this case, a pressure level within the first region 2a is lower than a pressure level within the second region 2b. The wave chamber 7 is pressurized with a pressure which corresponds in particular to the average between the pressure in the first region 2a and the second region 2b. Thus, a fluid pressure prevailing in the additional chamber 15, which is identical to the fluid pressure within the wave chamber 7, is greater than the fluid pressure within the first region 2a but lower than the fluid pressure within the second region 2b. This causes the first valve 8 to open and establish a connection between the additional chamber 15 and the first region 2a. At the same time, the second valve 9 remains closed. This results in pressure relief to the first region 2a.

[0034] Fig.Figure 7 shows a case in which a reversed pumping direction prevails. Here, the first connecting line 4 functions as the discharge line, while the second connecting line 5 functions as the supply line. Thus, the fluid pressure within the second region 2b is lower than in the additional chamber 15. As a result, the second valve 9 opens, while the first valve 8 remains closed. This results in pressure relief to the second region 2b.

[0035] This provides safe and reliable pressure relief. In both the first and second embodiments, pressure relief is achieved according to the same principle, by reducing the pressure to the supply line or the low-pressure region of the pump chamber connected to the supply line. This ensures that the drive unit 13 is relieved of high pressures, since only the pressure of the supplied fluid can act on the drive unit 13. List of reference symbols 1 fluid pump 2 pump chamber 3 Displacer assembly 4 first connecting cable 5 second connection cable 6 Wave 7 Wave chamber 8 first valve 9 second valve 10 first throttle valve 11 second throttle valve 12 Control unit 13 Drive unit 14 Housing part 15 Additional Chamber 16 Pressure equalization groove

Claims

[1] Fluid conveying pump (1) comprising: - a pump chamber (2), - a displacement assembly (3) arranged in the pump chamber (2) with a shaft (6) via which the displacement assembly (3) can be driven, the shaft (6) being mounted in a shaft chamber (7), - a first connecting line (4) connected for fluid communication to a first region (2a) of the pump chamber (2), - a second connecting line (5) separate from the first connecting line (4) and connected for fluid communication to a second region (2b) of the pump chamber (2), characterized by , that - a control unit (12) for connecting the wave chamber (7) to that connecting line of the first connecting line (4) and the second connecting line (5) which functions as a supply line for supplying fluid to the pump chamber (2), or for connecting the wave chamber (7) to that area of ​​the first area (2a) and the second area (2b) which is a low-pressure area of ​​the pump chamber (2), wherein the control unit (12) has a first valve (8) arranged between the wave chamber (7) and the first connecting line (4) or the first area (2a), which, when an overpressure prevails in the wave chamber (7) compared to the first connecting line (4) or the first area (2a),which releases the connection between the wave chamber (7) and the first connecting line (4) or the first region (2a) in the event of overpressure in the wave chamber (7) relative to the first connecting line (4) or the first region (2a), and which has a second valve (9) arranged between the wave chamber (7) and the second connecting line (5) or the second region (2b), which, when overpressure prevails in the wave chamber (7) relative to the second connecting line (5) or the second region (2b), releases the connection between the wave chamber (7) and the second connecting line (5) or the second region (2b) in the event of overpressure in the wave chamber (7) relative to the second connecting line (5) or the second region (2b), and wherein the displacement assembly (3) is configured to pump fluid in a first pumping direction from the first region (2a) into the second region (2b) and in a second pumping direction from the second region (2b) into the first region (2a). [2] Fluid feed pump (1) according to claim 1, characterized by at least one pressure compensation groove (16) extending parallel to the shaft (6), which is in particular introduced into the shaft (6) or into an element of the displacer assembly (3). [3] Fluid feed pump (1) according to claim 1, characterized by that the first valve (8) remains closed in the event of overpressure in the first connecting line (4) or the first area (2a) relative to the shaft chamber (7) and / or that the second valve (9) remains closed in the event of overpressure in the second connecting line (5) or the second area (2b) relative to the shaft chamber (7). [4] Fluid feed pump (1) according to one of the preceding claims, characterized by that the shaft chamber (7) is connected to the first connecting line (4) or the first region (2a) via a first throttle valve (10) and / or to the second connecting line (5) or the second region (2b) via a second throttle valve (11). [5] Fluid feed pump (1) according to one of the preceding claims, characterized by that a fluid pressure can be introduced into the shaft chamber (7) by the displacer assembly (3), which is between 70% and 30% of the output pressure generated by the displacer assembly (3) in the first connecting line (4) or second connecting line (5). [6] Fluid feed pump (1) according to one of the preceding claims, characterized by that a fluid pressure can be introduced into the shaft chamber (7) by the displacer assembly (3), which fluid pressure is between 60% and 40% of the output pressure generated by the displacer assembly (3) in the first connecting line (4) or second connecting line (5). [7] Fluid feed pump (1) according to one of the preceding claims, characterized bythat a fluid pressure can be introduced into the shaft chamber (7) by the displacer assembly (3) which amounts to 50% of the output pressure generated by the displacer assembly (3) in the first connecting line (4) or second connecting line (5). [8] Fluid feed pump (1) according to one of the preceding claims, characterized by a drive unit (13) for driving the shaft (6), wherein the drive unit (13) is hydraulically connected to the shaft chamber (7) so that pressure relief of the drive unit (13) can be effected by the control unit (12), and wherein the drive unit (13) is an electric motor. [9] Fluid feed pump (1) according to claim 8 characterized bya housing element (14) in which the shaft chamber (7) is formed, wherein an additional chamber (15) is formed between the drive unit (13) and the housing element (14), wherein the shaft chamber (7) is connected to the additional chamber (15) for fluid transmission, and wherein the additional chamber (15) is connected to the first region (2a) and / or the second region (2b) for fluid transmission. [10] Fluid feed pump (1) according to one of the preceding claims, characterized by that the first connecting line (4), the second connecting line (5) and the shaft chamber (7) open into the pump chamber (2) on the same axial side with respect to the shaft (6). [11] Fluid feed pump (1) according to one of the preceding claims, characterized by that the shaft chamber (7) is formed adjacent to the pump chamber (2) to form a common free space. [12] Fluid feed pump (1) according to one of the preceding claims, characterized bythat the displacement assembly (3) has a gear ring pump device with a gear ring and a gear running eccentrically in the gear ring.

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