Fluid conveying system for conveying a fluid to at least one consumer
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- VOLKSWAGEN AG
- Filing Date
- 2011-08-20
- Publication Date
- 2026-06-11
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[0001] The invention relates to a fluid conveying system for conveying a fluid to at least one consumer, in particular a fuel supply for an internal combustion engine of a motor vehicle.
[0002] A high-pressure pump is used to supply fuel to an internal combustion engine with fuel injection. The fuel, pressurized by the high-pressure pump, typically flows into a common rail from which it is injected into the engine's combustion chambers as needed. The generation of this high pressure inevitably creates pressure pulsations, which propagate through the fuel lines in the vehicle, generating unwanted vibrations and noise.
[0003] Publication EP 0 682 177 A1 describes a fuel injection system in which a reduction of the pulsation effect is achieved. The injection pump of this system has a pulsation-reducing device in a return line, in which flowing fuel is directed to a receiving cavity when a bypass valve is open. The pulsation-reducing device includes a damping chamber that is connected to the return line via a small-diameter connection.
[0004] Another damping device for reducing pulsation in radial or axial piston machines operating as pumps or motors is described in German publication DE 197 06 116 C2. The device has a storage element connected to the high-pressure side, which in turn is connected to the cylinder chamber of the machine. To reduce pulsation, a check valve is arranged in a connecting channel between the storage element and the cylinder chamber.
[0005] German patent application DE 101 49 412 C1 describes a device for damping pressure pulsations in the fuel system of an internal combustion engine. The device is part of a high-pressure pump that injects fuel under high pressure into a manifold ("rail"). The fuel, delivered from a fuel tank by a fuel pump, passes to a pressure damper connected in parallel to a delivery chamber of the high-pressure pump. The pressure damper consists of a gas volume generated during operation by gaseous fuel, which is elastically compressed. Pressure surges are further dampened by a passive damping volume and by an elastic hose that forms a low-pressure fuel line.
[0006] German patent application DE 31 46 454 A1 describes an element for damping pressure fluctuations in a fuel delivery system for an internal combustion engine. The damping element, through which the fuel flows and which elastically expands in response to each pressure fluctuation, is arranged in a delivery line leading from a positive displacement pump to the internal combustion engine. The inlet and outlet openings in the damping element are arranged such that the flow direction of the fuel within the damping element is redirected, causing the fuel to back up.
[0007] German patent application DE 10 2010 000 508 A1 describes a pulsation reduction device arranged in parallel with a high-pressure fuel pump. The pulsation reduction device has a main fuel line and two branch sections extending from it, namely a downstream section and an upstream section, which are connected to each other via a connecting line. A check valve is fitted to the upstream section of the connecting line. The check valve moves the fuel from the upstream branch section of the main fuel line to the connecting line when a pressure difference between the fuel pressure on the upstream side of the check valve and the fuel pressure on the downstream side of the valve becomes greater than or equal to a predetermined pressure.
[0008] Publication EP 1 342 912 A2 describes a fuel supply system for an internal combustion engine, comprising a low-pressure system and a high-pressure system. The high-pressure system includes a high-pressure pump, and the low-pressure system a demand-controlled fuel pump. The two pumps are connected via a fuel line. A throttle check valve is located in the fuel line between the fuel pump and the high-pressure pump. This valve has a smaller opening cross-section relative to the fuel line. It is stated that the throttle check valve reduces pressure pulsations in the low-pressure system caused by the fuel pump. Pressure waves propagating from the fuel pump along the fuel line towards the high-pressure pump are dampened in this direction by the small opening cross-section of the throttle check valve.
[0009] The prior art also includes the publications DE 100 10 517 A1 and US 4 118 156 A.
[0010] It has been shown that known devices for pulsation reduction in fuel injection systems are not suitable for effectively suppressing the pressure pulsations caused by the high-pressure fuel pump. These pulsations generate significant noise in the vehicle, presumably due to the pressure pulsations and the resulting resonances.
[0011] This problem is solved by the fluid conveying system according to claim 1 for conveying a fluid (liquid or gas) to at least one consumer.
[0012] Preferred embodiments of the invention are specified in the dependent claims.
[0013] The fluid supply system according to the invention serves to supply fuel to an internal combustion engine of a motor vehicle. In this case, the fluid reservoir is formed by a fuel tank and the quantity of fuel stored therein, the high-pressure pump by a high-pressure pump, the fluid line by a fuel line, and the at least one consumer by a high-pressure injection valve of the internal combustion engine downstream of the high-pressure pump. The high-pressure pump increases the pressure in the fuel and delivers it to the at least one downstream high-pressure injection valve. Thus, the fuel supply system comprises a fuel tank, a high-pressure pump for delivering fuel to at least one downstream high-pressure injection valve of the internal combustion engine, a fuel line leading from the fuel tank to the high-pressure pump, and a check valve in the fuel line leading to the high-pressure pump.In accordance with the invention, a fluid connection for the fuel between the fuel tank and the high-pressure pump is available exclusively via the check valve.
[0014] The check valve is connected in series with the fluid reservoir or fuel tank and the high-pressure pump. This means the check valve interrupts the fluid or fuel line, allowing fluid or fuel to flow only when the check valve is open. A bypass, such as a restrictor, in parallel with the check valve is not provided.
[0015] In contrast to the fuel supply system according to EP 1 342 912 A2, in which a throttle check valve is arranged in the fuel line between the fuel tank and the high-pressure pump, a pressure pulsation according to the present invention cannot dissipate via a bypass towards the low-pressure side. This is because, at the beginning of a pressure pulse, which propagates from the high-pressure pump in the opposite direction to the fuel delivery direction, the check valve very quickly closes the fuel line, preventing the pulsations from propagating into the upstream line. Due to the lack of a bypass, the pressure pulsations caused by the high-pressure pump cannot continue into the low-pressure section of the fuel line.
[0016] The check valve closes depending on the current pressure applied to it.
[0017] With a sufficiently fast response time of the check valve, the closing time is so fast that the pressure fluctuations cannot propagate into the low-pressure section even if the oscillation frequency of the pulsations is relatively high.
[0018] The throttle of the throttle check valve in EP 1 342 912 A2, however, has a twofold negative effect on the transmission of pressure pulsations caused by the high-pressure pump to the low-pressure section: Firstly, during a period of high instantaneous pressure on the high-pressure side of the valve, fuel flows through the throttle to the low-pressure side, thus generating a pressure surge there as well. Secondly, this additional pressure surge increases the pressure on the low-pressure side, shifting the switching point for closing the valve during the pressure pulse to a higher pressure. This results in resonance amplifications in the system. This effect is greater the larger the free cross-section of the throttle.
[0019] In the case of the present invention, without such a bypass (i.e., the fuel delivery path leads exclusively through the check valve), the check valve closes immediately as soon as a predetermined instantaneous pressure is reached on the high-pressure side of the valve and only opens again when the pressure has dropped below this value. Therefore, without fuel being able to reach the high-pressure pump via a bypass to the check valve, the noise and vibrations caused by pressure pulsations in a motor vehicle are reduced or suppressed by the use of the check valve.
[0020] Such noises and vibrations caused by pressure pulsations occur particularly when the high-pressure pump builds up back pressure, especially when less fuel is required in certain driving situations. These noises and vibrations are precisely what the fuel supply system according to the invention suppresses. Thus, pressure resonances within the system are also prevented. Furthermore, EP 1 342 912 A2 assumes that the throttle of the throttle check valve is essential, as it states that the pressure pulsations caused by a low-pressure pump in the low-pressure section of the system are dampened by the small opening cross-section of the throttle check valve.
[0021] According to the present invention, the check valve closes when the instantaneous pressure generated by the pressure pulsations of the high-pressure pump in the part of the fluid line between the check valve and the high-pressure pump is greater than the difference between the pressure P1 in the part of the fluid line between the check valve and the fluid reservoir and any spring pressure P3 that may be present in the check valve: P2,P2',P2''>P1−P3(condition for closing the check valve)
[0022] Accordingly, the check valve according to the present invention opens only when the instantaneous pressure P2, P2', P2'' generated by the pressure pulsations of the high-pressure pump in the part of the fluid line between the check valve and the high-pressure pump is less than the difference between the pressure P1 in the part of the fluid line between the check valve and the fluid reservoir and any spring pressure P3 that may be present in the check valve: (P2,P2',P2'') <P1−P3(Bedingung fu¨r das O¨ffnen des Ru¨ckschlagventils)
[0023] The pressure P1 in the section of the fluid line between the check valve and the fluid reservoir can be generated, for example, by a low-pressure pump. The spring pressure in the check valve can be generated, for example, by a spring force acting on a valve element within the check valve.
[0024] By placing the check valve in the fluid line, it is further advantageously achieved that fuel which is under pressure in the high-pressure area of the fuel system cannot flow out during the assembly of the fuel line.
[0025] Similarly, a check valve can also be advantageously used in other fluid conveying systems, for example in water conveying. In this case, pressure pulsations caused by a high-pressure pump on the outlet side are reduced or suppressed according to the invention by installing a check valve on the low-pressure side of the high-pressure pump, whereby the fluid is routed exclusively through the check valve and not additionally through a bypass.
[0026] In this case, a check valve is defined as a fluid switching element that switches the flow of the fluid between the two switching states 'flow' and 'blocking the flow', i.e., that switches the flow on or off without providing an additional fluid delivery path.
[0027] The check valve is integrated into a housing. This allows the damping effect to be further increased because the oscillating mass of the valve is increased.
[0028] The fluid supply system also includes a low-pressure pump for pumping the fluid from the fluid reservoir. This low-pressure pump can, for example, be a single-piston pump. The low-pressure pump pumps the fluid or fuel, for example, at a pressure of approximately 5 bar, into the fluid line or fuel line and thus to the high-pressure pump. The low-pressure pump therefore creates a pre-pressure at a check valve located in the fluid line, which counteracts the closing of the valve as long as the instantaneous back pressure generated by the high-pressure pump is not higher. Thus, the fluid line is constantly under an elevated static pressure, which can be limited to an upper pre-supply limit pressure, for example, 6.5 bar, for example, by means of a control valve. In a further preferred embodiment of the invention, the low-pressure pump is arranged on or in the fluid reservoir or fuel tank.
[0029] The check valve features a valve element pre-tensioned against a valve seat, opposing the direction of fluid flow from the reservoir to the high-pressure pump. This ensures a rapid response time for the check valve. Furthermore, it reduces the back pressure required to close the valve, thus further reducing pressure pulsations and virtually eliminating them.
[0030] The valve element of the check valve is pre-tensioned by a spring that acts against a delivery pressure generated by the low-pressure pump. This design is simple and can be implemented with low manufacturing costs. The spring acting on the valve element can be a coil spring, and in particular a compression spring or a tension spring. The use of a compression spring is a preferred embodiment. The spring acts on the valve element against the direction of fluid flow through the check valve.
[0031] The check valve can be used in virtually any configuration. Generally, the valve comprises a valve body, which is a hollow element with an interior space. This interior space is connected to both the low-pressure and high-pressure sections of the fluid line. The interior space between the two connection ports of the check valve is divided into two compartments—a low-pressure compartment and a high-pressure compartment—by a valve seat and the valve element that is mounted on the valve seat. The closing mechanism of the check valve can, for example, be a flap, a ball, a cylinder, or another type of closing element.The terms 'low-pressure section', 'low-pressure chamber', 'high-pressure section' and 'high-pressure chamber' each refer to the instantaneous pressure relative to each other, because the upstream pressure downstream of the check valve in the direction of delivery is usually higher than the pressure upstream of the check valve caused by the high-pressure pump.
[0032] The flow cross-sections inside the check valve and in the area of the valve seat, as well as in the connecting ports to the downstream and upstream sections of the fluid line, the geometry of the fluid path within the valve, the spring force, and the mass of the valve element all determine the response time / closing and opening time of the valve. The lower the mass of the valve element and the stronger the spring force, the shorter the response time. Reduced flow cross-sections have the same effect, as they force a higher flow velocity through the valve. A fast response time ensures that the static pressure in the two sections of the fluid line upstream and downstream of the check valve is largely or completely equal.
[0033] In principle, the check valve can be installed at any connection point of a fuel line in a fuel supply system. It has proven particularly advantageous to position the check valve as close as possible to the high-pressure pump of the fuel system. Therefore, in a preferred embodiment of the invention, a low-pressure section of the fuel line is arranged upstream of the check valve between the fuel tank and the check valve in the underbody area of the vehicle, extending from the fuel tank to a point near (in the vicinity of) the internal combustion engine. The check valve is therefore preferably located at this point. It is thus particularly advantageous to be positioned in close proximity to the high-pressure pump and therefore to the internal combustion engine.This means that the high-pressure section of the fuel line is short, while the majority of the fuel line, the low-pressure section, extends from the fuel tank to near the internal combustion engine.
[0034] Since pressure pulsations occur exclusively in the high-pressure section of the fuel line between the check valve and the high-pressure pump, and can therefore only generate noise and vibration there, their effect is spatially very limited, thus achieving the desired effect to a particularly large extent. Furthermore, it has been shown that an existing coupling for connecting underbody lines to the engine-side hoses is a suitable location for this. The check valve can therefore be installed at this point during vehicle assembly.
[0035] In a further preferred embodiment of the invention, a fuel filter is arranged in the low-pressure section of the fuel line between the fuel tank and the check valve.
[0036] The following figures serve to further illustrate the invention. They show, in detail: Fig. 1 A schematic side view, partially in section through a fuel supply of a motor vehicle; Fig. 2 schematic representations ( Fig. 2a, Fig. 2b, Fig. 2c, Fig. 2d) of the check valve in a side sectional view; (a) in the fuel line with the high-pressure pump; (b) in a first working stroke with the closing device closed; (c) in a second working stroke with the closing device open and with fuel flowing in; (d) in a third working stroke with the closing device closed again; Fig. 3 A perspective view of a check valve in side view, cut away.
[0037] In the figures, identical reference symbols denote elements with the same function.
[0038] In Fig. Figure 1 shows the fuel supply system with a fuel tank 100 and a fuel pump 200 located in the fuel tank. The fuel tank 100 is preferably located in a rear section of the vehicle. The fuel 110 is in liquid form in the fuel tank 100, up to a level of 115. The fuel pump 200 is a single-piston pump. It is controlled by an engine control unit. It draws the fuel 110 from the reservoir 110 and delivers it at a pressure of up to 6.5 bar via a delivery line 210 to a unit 220, which consists of a fuel filter and a pressure regulating valve. The pressure regulating valve in the unit 220 limits the fuel pressure in the low-pressure section 310 of the fuel line 300 branching off there to a maximum value of 6.5 bar.If the pre-pressure in the discharge line 210 should exceed this value, the pressure regulating valve directs excess fuel 110 back into the fuel tank 100 via the return line 230.
[0039] The fuel line 300 is formed by a low-pressure section 310 and a high-pressure section 320. These two sections 310 and 320 are connected to each other via a check valve 400. The low-pressure section 310 of the fuel line 300 is preferably installed as an underbody line on the vehicle. The check valve 400 is connected to the high-pressure pump 500 close to the engine. Therefore, the check valve 400 is located near the internal combustion engine (not shown), on which the high-pressure pump 500 is mounted. Thus, the low-pressure section 310 of the fuel line 300 extends close to the internal combustion engine. The high-pressure section 320 of the fuel line 300 is relatively short. By spatially limiting the pressure pulsations caused by the high-pressure pump 500 to the high-pressure section 320, noise and vibrations generated by these pressure pulsations are minimized.The fuel 110 must pass through the check valve 400 on the fuel delivery path from the fuel tank 100 to the high-pressure pump 500, as no further delivery path, such as a bypass connected in parallel to the check valve 400, is available.
[0040] The high-pressure pump 500 comprises a pump piston 510, which is driven by the internal combustion engine, for example via a chain drive. The high-pressure pump 500 also has a pressure damper 520 in the form of elastic diaphragms, which deform elastically due to the pulsations generated in the high-pressure pump, thereby dynamically increasing a damping volume 540 and thus damping the pulsation. However, this damping, unlike the pulsation reduction according to the invention, acts passively and is only partially effective. The high-pressure pump 500 directs the fuel 110, which is under high pressure, into a manifold (rail; not shown), from which it is successively directed to the high-pressure injection valves 600.
[0041] In Fig. Figure 2a shows a schematic diagram of an arrangement with the check valve 400, the low-pressure section 310 and the high-pressure section 320 of the fuel line 300 and with the high-pressure pump 500.
[0042] Fuel flows in the direction designated PF1 from the fuel pump (not shown) to the check valve 400 and from there to the high-pressure pump 500, where it is pressurized and then directed in the direction designated PF3 to the high-pressure injectors (also not shown). The fuel flowing in the low-pressure section 310 of the fuel line 300 is subject to only slight or practically no pressure pulsations (DP1). In contrast, the pressure pulsations (DP2) caused by the high-pressure pump 500, which propagate in the opposite direction to the flow direction PF1 in the direction PF2 towards the check valve 400, are much stronger. These pressure pulsations cause loud noises in the fuel line 300 and in other parts of the vehicle connected to this line.By arranging the check valve 400 in the fuel line 300 such that a low-pressure section 310 and a high-pressure section 320 are formed, the pressure pulsations on the high-pressure side can only continue as far as the check valve 400, but not beyond into the low-pressure section.
[0043] A more detailed explanation of the construction of the 400 check valve will follow, based on... Fig. 3 given. In Fig. Figure 2a shows schematically that the check valve 400 has a closing element formed by a valve element 410 (shown here as a ball) and preferably a compression spring 430 pressing this valve element 410 against a valve seat 420.
[0044] The operation of the 400 check valve in the various operating cycles of the high-pressure pump is shown schematically using the following diagram: Fig. 2b, Fig. 2c and Fig. 2d explained:
[0045] In Fig. Figure 2b shows a first operating cycle, characterized by the fact that the check valve 400 is closed, i.e., the valve element 410 is firmly seated on the valve seat 420, so that fuel 110 cannot flow through the check valve 400. Therefore, the interior 440 of the check valve 400 is not yet filled with fuel 110. To the left of the diagram for the check valve 400, the strong pressure pulsations in the high-pressure section 320 of the fuel line are symbolized by the sine wave shown there. The force pressing from the left against the valve element 410 due to an instantaneous pressure P2 acting on the valve element is symbolized by the arrow PF2 and by its vertical position relative to the depicted sine wave. In this case, the instantaneous pressure P2 in the high-pressure section 320 is greater than its minimum.
[0046] Fuel 110 is pumped by the fuel pump through the low-pressure section 310 towards PF1 at a relatively constant delivery pressure P1 into the check valve 400. In addition, a spring force acts on the valve element 410 in the opposite direction to PF1, resulting in an additional spring pressure P3 exerted on the valve element. Thus, the instantaneous pressure P2 – which is greater than its minimum in the high-pressure section 320 – and the spring pressure P3, generated by the spring force, act on the valve element 410 from the high-pressure section 320, while the pressure P1 from the low-pressure section 310 acts on the valve element 410. The valve element 410 closes when P2+P3>P1.
[0047] This is the case here.
[0048] In Fig. Figure 2c shows a second working stroke, characterized by the fact that the valve element 410 is open, allowing fuel 110 to flow from the low-pressure section 310 into the interior 440. The force pressing against the valve element 410 from the left due to an instantaneous pressure P2' acting on the valve element 410 is symbolized by the arrow PF2 and by its vertical position relative to the depicted sine wave. In this case, the instantaneous pressure P2' in the high-pressure section 320 is minimal.
[0049] Thus, the instantaneous pressure P2' and, in the same direction, the spring pressure P3 generated by spring force act on the valve element 410, originating from the high-pressure section 320, and the pressure P1 acts on the valve element 410 originating from the low-pressure section 310. The valve element 410 opens when P2+P3 <P1.
[0050] This is the case here.
[0051] In Fig. Figure 2d shows a third working cycle, characterized by the fact that the valve element 410 is closed again, so that fuel 110 from the low-pressure section 310 can no longer flow into the interior 440. The force pressing against the valve element 410 from the left due to an instantaneous pressure P2" acting on the valve element is symbolized by the arrow PF2 and by its vertical position relative to the depicted sine wave. In this case, the instantaneous pressure P2" is at its maximum in the high-pressure section 320.
[0052] Thus, the instantaneous pressure P2 and, in the same direction, the spring pressure P3 generated by spring force act on the valve element 410, originating from the high-pressure section 320, and the pressure P1 acts on the valve element 410 originating from the low-pressure section 310. The valve element 410 closes when P2''+P3>P1.
[0053] This is the case here. P2, P2“ > P2'.
[0054] In Fig.Figure 3 shows the structure of the check valve 400 in one possible embodiment, comprising a valve housing 450, a second high-pressure-side connection 460 which is rigidly connected to the valve housing 450, and a first low-pressure-side connection 470, which is designed as a detent element with an axial bore for the passage of fuel. The first connection 470 detent in the low-pressure-side inlet area of the valve housing 450 and is sealed by a seal 475. Above the illustration of the check valve 400, the delivery direction PF1 for the fuel 110 is shown. Therefore, the low-pressure section 310 of the fuel line is connected to the first low-pressure-side connection 470, and the high-pressure section 320 of the fuel line is connected to the second high-pressure-side connection 460.
[0055] The valve housing 450 is provided with an interior 440. A valve seat 420, in the form of a seal with a central opening, is located in the interior 440. The valve seat 420 divides the interior 440 into a low-pressure chamber 444 and a high-pressure chamber 442. A valve element 410, here in the form of a valve tappet with a valve disc 412 and a valve stem 414, can be seated on the valve seat 420 and close the check valve 400. The valve element 410 is further pre-tensioned by a compression spring 430. The compression spring 430 is supported on one side by the rear of the valve seat 420 and on the other side by retaining clips 416 of the valve element 410, thus pressing it against the valve seat 420. Reference symbol list 100 fuel tank 110 Fuel 115 Fuel level 200 fuel pump 210 Discharge line 220 units 230 Return line 300 fuel line 310 Low-pressure section 320 High-pressure section 400 Check valve 410 Valve element 412 Valve plates 414 Valve stem 416 retaining clips 420 Valve seat 430 compression spring 440 Interior of the check valve 442 High-pressure room 444 Low-pressure room 450 valve housings 460 high-pressure side connection nozzle 470 low-pressure side connection nozzle 475 Seal 500 high-pressure pump 510 pump pistons 520 pressure dampers 540 damping volume 600 High-pressure injection valve P1 Delivery pressure in the low-pressure section P2, P2', P2" Instantaneous pressure in the high-pressure section P3 spring pressure PF1 Delivery direction from the fuel pump to the check valve PF2 Direction of pressure pulsations from the high-pressure pump to the check valve PF3 Delivery direction from the high-pressure pump to the high-pressure injectors DP1 Pressure pulsations in the low-pressure section DP2 Pressure pulsations in the high-pressure section
Claims
Fluid conveying system for conveying a fluid (110) to at least one consumer (600), comprising: a) a fluid reservoir (100), b) a high-pressure pump (500) for conveying the fluid (110) in the fluid conveying system, c) a fluid line (300) leading from the fluid reservoir (100) to the high-pressure pump (500), and d) a check valve (400) arranged in the fluid line (300) leading from the fluid reservoir (100) to the high-pressure pump (500), wherein a fluid connection between the fluid reservoir (100) and the high-pressure pump (500) is available exclusively via the check valve (400), wherein the fluid connection has a low-pressure section (310) upstream of the check valve (400) and a high-pressure section (320) downstream of the check valve (400), wherein an interior (440) of a The valve body (450) of the check valve (400) is divided by a valve seat (420) into a low-pressure chamber (444) and a high-pressure chamber (442),wherein the check valve (400) has a valve element (410) as a closing device which is biased in the direction (PF2) of the pressure pulsations (DP2) from the high-pressure pump (500) to the check valve (400) against the direction (PF1) of the delivery of the fluid from the fluid reservoir (100) to the high-pressure pump (500), characterized in that the valve element (410) arranged in the high-pressure chamber (442) is biased by means of a spring arranged in the low-pressure chamber (444), which with its spring pressure (P3) acts against a delivery pressure (P1) generated by a low-pressure pump (200) in the fluid line (300) in the low-pressure section (310), wherein the delivery pressure (P1) opposes the closing of the valve element (410) of the check valve (400) as long as the instantaneous back pressure (P2) generated by the high-pressure pump (500) P2', P2") is not higher than the delivery pressure (P1), so that the generated delivery pressure (P1) in the check valve (400) and the instantaneous back pressure (P2, P2',P2”) causes the low-pressure section (310) to close or open relative to the high-pressure section (320) depending on the instantaneous back pressure (P2, P2', P2”) acting in the high-pressure section (320). Fluid conveying system according to claim 1, characterized in that the spring is a coil spring or a tension spring or a compression spring (430). Fluid conveying system according to claim 2, characterized in that the compression spring (430) is supported on the one hand on a rear side of the valve seat (420) and on the other hand on retaining clips (416) of the valve element (410) and presses the valve element (410) against the valve seat (420). Fluid conveying system according to claim 1, characterized in that the check valve (400) closes immediately when an instantaneous back pressure (P2, P2', P2") generated by the pressure pulsations of the high-pressure pump (500) in the high-pressure section (320) between the check valve (400) and the high-pressure pump (500) is greater than the difference between the delivery pressure (P1) in the low-pressure section (320) between the check valve (400) and the fluid reservoir (100) and the spring pressure (P3) present in the check valve (400) due to the pre-tensioned spring, wherein the check valve (400) opens only when the instantaneous back pressure (P2, P2') generated by the pressure pulsations of the high-pressure pump (400) is greater than the difference between the delivery pressure (P1) in the low-pressure section (320) between the check valve (400) and the fluid reservoir (100) and the spring pressure (P3) present in the check valve (400) due to the pre-tensioned springP2'') in the high-pressure section (320) between the check valve (400) and the high-pressure pump (500) is smaller than the difference between the delivery pressure (P1) in the low-pressure section (320) between the check valve (400) and the fluid reservoir (100) and the spring pressure (P3) in the check valve (400) due to the pre-tensioned spring. Fluid conveying system according to claim 1, characterized in that the valve element (410) closes in a first working cycle when, originating from the high-pressure section (320), the instantaneous back pressure (P2, P2', P2'') and, in the same direction, the spring pressure (P3) generated by the spring force of the spring are greater than the delivery pressure (P1) acting on the valve element (410) originating from the low-pressure section (310), wherein the valve element (410) opens in a second working cycle when, originating from the high-pressure section (320), the instantaneous back pressure (P2') and, in the same direction, the spring pressure (P3) generated by the spring force of the spring are less than the delivery pressure (P1) acting on the valve element (410) originating from the low-pressure section (310), wherein the valve element (410) is closed again in a third working cycle.if the instantaneous back pressure (P2) originating from the high-pressure section (320) and the spring pressure (P3) generated by the spring force of the spring in the same direction are greater than the delivery pressure (P1) acting on the valve element (410) originating from the low-pressure section (310). Fluid supply system for supplying a fluid (110) to at least one consumer (600) according to claim 1, characterized in that the fluid supply system serves to supply fuel to an internal combustion engine of a motor vehicle, that the fluid reservoir is formed by a fuel tank (100), that the high-pressure pump is formed by a high-pressure pump (500) for supplying fuel (110), that the fluid line is formed by a fuel line, and that the at least one consumer is formed by a downstream high-pressure injection valve (600) of the internal combustion engine, wherein the high-pressure pump (500) supplies the fuel (110) to the at least one downstream high-pressure injection valve (600). Fluid conveying system for conveying a fluid (110) to at least one consumer (600) according to claim 1, characterized in that the low-pressure pump (200) is arranged on or in the fluid reservoir (100). Fluid conveying system for conveying a fluid (110) to at least one consumer (600) according to claim 1, characterized in that a low-pressure section (310) of the fuel line (300) is arranged between the fuel tank (100) and the check valve (400) in the underbody area of the motor vehicle and extends from the fuel tank (100) to the internal combustion engine area.