High-pressure cleaning device and method for operating a high-pressure cleaning device

Abstract

The invention relates to a high-pressure cleaning device comprising a high-pressure pump (3) for conveying liquid in a conveying direction (50) and a main line (5) through which liquid can be conveyed by means of the high-pressure pump (3). The main line (5) has a suction chamber (9) upstream of the high-pressure pump (3) and a pressure chamber (10) downstream of the high-pressure pump (3), between which a return line (12) is arranged for fluidic connection. The high-pressure cleaning device (1) comprises a start valve (20) for interrupting a liquid flow through the return line (12) and a check valve (60) which is arranged in the pressure chamber (10) downstream of the return line (12). The high-pressure cleaning device (1) includes an auxiliary valve (40), separate from the start valve (20), for interrupting the fluidic connection between the pressure chamber (10) and the suction chamber (9) through the return line (12), which is biased to a closed state.The high-pressure cleaning device (1) is designed such that the check valve (60) opens at a lower pressure than the auxiliary valve (40).

Description

The invention relates to a high-pressure cleaning device according to the preamble of claim 1 and a method for operating a high-pressure cleaning device according to the preamble of claim 10. The use of a start valve in a high-pressure cleaning unit is described in EP 4 480 592 A1. A return line, in which the start valve is located, is provided to facilitate the starting of the high-pressure pump or the motor driving the high-pressure pump. The high-pressure cleaning unit is designed so that the start valve closes in such a way that no liquid can flow from the pressure chamber into the suction chamber through the return line when the flow rate through the start valve corresponds to at least a starting volume threshold. Below the starting volume threshold, however, liquid flow through the return line is possible. This facilitates the starting of the high-pressure pump or the high-pressure pump motor. Particularly when the main line valve is closed, the high-pressure pump does not have to work against a high pressure in the pressure chamber.During the start-up phase, the high-pressure pump can circulate fluid from the pressure chamber to the suction chamber via the return line without having to work against high back pressure at initially low torque or speed. This allows the pump to reach a speed sufficient to provide adequate torque at the appropriate back pressure before reaching the starting volume threshold and closing the starting valve. Only after the high-pressure pump or motor has reached this speed does it have to work against higher pressure in the pressure chamber. With prior art high-pressure cleaning equipment, it can happen that the starting volume threshold is not reached despite a long start-up phase for the high-pressure pump or its motor, even if the motor has already reached its operating speed. The invention is based on the objective of further developing a generic high-pressure cleaning device in such a way that the desired operating conditions of a high-pressure cleaning device with a starting valve are achieved quickly and reliably. This problem is solved by a high-pressure cleaning device with the features of claim 1. A further object of the invention is to further develop a generic method for operating a high-pressure cleaning device with a starting valve in such a way that the desired operating conditions of the high-pressure cleaning device are achieved quickly and reliably. This problem is solved by a method having the features of claim 10. The high-pressure pump of a high-pressure cleaning device is often filled with air during startup or after running dry. The invention is based on the understanding that this can cause the valves of the high-pressure cleaning device, particularly the differential pressure valves, to exhibit unintended switching behavior. With regard to the start valve, this can result in the start valve failing to close. The required starting volume threshold is never reached because air is unintentionally recirculated through the return lines. To prevent this, the invention provides an additional valve to interrupt the fluidic connection between the pressure chamber and the suction chamber that is possible via the return line. In its closed state, the additional valve is biased in the opposite direction to the flow of liquid in the high-pressure cleaning device.The flow direction is determined primarily by the piping system of the high-pressure cleaning device. The flow direction is the direction in which a fluid, particularly a liquid, flows due to the piping layout and the action of the high-pressure pump. The flow direction can vary in different sections of the piping system. The high-pressure cleaning device includes a check valve located in the pressure chamber downstream of the return line. The check valve prevents fluid flow against the flow direction. The check valve is biased into a closed position opposite to the flow direction. According to the invention, the high-pressure cleaning device is designed such that the check valve opens at a lower pressure, particularly a lower differential pressure, than the auxiliary valve.In particular, the check valve opening pressure required to open the check valve is lower than the auxiliary valve opening pressure required to open the auxiliary valve. Specifically, an auxiliary valve pressure differential between the area upstream of the auxiliary valve and the area downstream of the auxiliary valve, particularly in the return line, is required to open the auxiliary valve. Specifically, a check valve pressure differential between the area upstream of the check valve and the area downstream of the check valve, particularly in the pressure chamber, is required to open the check valve. Specifically, the check valve pressure differential is lower than the auxiliary valve pressure differential. Because the check valve opens at a lower pressure than the auxiliary valve, a lower pressure differential is present when the high-pressure pump starts up.The check valve of the motor driving the high-pressure pump opens due to any air potentially present in the high-pressure pump, while the auxiliary valve remains closed. This prevents air from being pumped in a closed loop through the return line and the auxiliary valve. The air escapes from the high-pressure cleaner through the check valve and the main line. The high-pressure pump then pumps fluid. The pressure generated by the fluid is then sufficient to open the auxiliary valve. This allows fluid to be pumped in a closed loop via the return line during a start-up phase, as is already possible in the prior art. The high-pressure pump, or the motor driving the high-pressure pump, does not have to work against excessive pressure.Only when the high-pressure pump, and in particular the motor driving the high-pressure pump, has reached a sufficient speed and the flow rate has thereby reached the starting volume threshold, does the starting valve close and the starting phase of the high-pressure cleaner is complete. This allows the desired operating conditions of the high-pressure cleaner to be reached quickly and reliably. Unwanted recirculation of air is thus reliably prevented. The check valve is biased into the closed position by a return force. The auxiliary valve is biased into the closed position by an auxiliary valve force. A fluid, in particular a liquid and / or air, can act on the check valve with a return cross-sectional area, particularly a hydraulically effective one. The return force, the return cross-sectional area, the auxiliary valve force, and the auxiliary valve cross-sectional area are specifically coordinated such that the check valve opens at a lower pressure, particularly a lower differential pressure, and particularly a lower opening pressure than the auxiliary valve.In particular, the check valve restoring force, the check valve cross-sectional area, the auxiliary valve force, and the auxiliary valve cross-sectional area are coordinated so that the check valve pressure differential is smaller than the auxiliary valve pressure differential. This ensures, in a simple way, that the check valve opens at a lower pressure than the auxiliary valve. In particular, the auxiliary valve force is greater than the check valve restoring force. Specifically, the auxiliary valve cross-sectional area is smaller than the check valve cross-sectional area. This makes it easy to ensure that the check valve opens at a lower pressure than the auxiliary valve. In particular, the check valve has a return spring. The return spring provides the return force. Alternatively or additionally, it is provided that the auxiliary valve has an auxiliary valve spring. The auxiliary valve spring provides the auxiliary valve force. The starting valve has a starting valve element. Specifically, the starting valve element is designed separately from an auxiliary valve element of the auxiliary valve. This allows the starting valve and the auxiliary valve to be easily arranged at different locations within the high-pressure cleaner. In particular, the starting valve can be arranged in the main line. Simultaneously, the auxiliary valve can be arranged in the return line. In particular, the start valve is located in the main line downstream of the high-pressure pump. This ensures that the full, undivided flow of fluid reaches the start valve. Since no portion of the flow is diverted from the main line before it reaches the start valve, the valve opens and closes reliably. The parameter that determines the opening and closing of the start valve is reliably reproducible. Because the flow reaching the start valve is undivided, external parameters that influence the amount of flow diverted into the return line are irrelevant. Specifically, the flow rate at the start valve is independent of the nozzle cross-section of any nozzle installed at the discharge port. Therefore, the timing, or engine speed, at which the start valve opens and closes is also reproducible.This means that the pressure against which the high-pressure pump must work during start-up is also reproducible. The placement of the start valve in the main line allows it to operate reliably and consistently. Accordingly, the start valve closes reliably only when the engine has reached a speed within its operating range during start-up. In particular, the start valve element is located entirely within the main line, specifically within the pressure chamber. Specifically, the start valve element is located entirely outside the return line. Specifically, a start valve seat of the start valve is formed at an inlet of the return line. This ensures, in a simple manner, that the full, undivided volume flow of the liquid reaches the start valve before any portion of the volume flow is diverted from the main line. In particular, the auxiliary valve is located in the return line. This allows for a simple interruption of the fluidic connection between the pressure chamber and the suction chamber via the return line. In particular, the auxiliary valve is located downstream of the starting valve. This makes it easy to position the starting valve in the main line. To close the start valve, a pressure differential is required between the area upstream of the start valve and the area downstream of the start valve, particularly the area in the return line downstream of the start valve. Specifically, the pressure differential of the auxiliary valve is smaller than the pressure differential of the start valve. The high-pressure cleaner is designed such that during the start-up phase of the high-pressure pump, and especially the motor driving the high-pressure pump, the auxiliary valve opens before the start valve closes. This ensures that during the start-up phase of the high-pressure cleaner, the high-pressure pump, and especially the motor, can circulate fluid via the return line and does not have to work against the high pressure in the pressure chamber, particularly in the area upstream of the spray nozzle.Specifically, the start valve closes when the fluid flow rate in the pressure chamber exceeds a start flow rate threshold. Specifically, the auxiliary valve opens when the pressure at the auxiliary valve exceeds an opening pressure threshold. The opening pressure threshold is exceeded when the fluid flow rate in the pressure chamber exceeds an opening flow rate threshold. Specifically, the start flow rate threshold is greater than the opening flow rate threshold. This ensures that the auxiliary valve opens during the start-up phase before the start valve closes. According to the inventive method, the high-pressure cleaning device includes an auxiliary valve, separate from the start valve, for interrupting the fluidic connection between the pressure chamber and the suction chamber via the return line. The auxiliary valve is biased in the closed position in the direction opposite to the conveying direction. The high-pressure cleaning device also includes a check valve located in the pressure chamber downstream of the return line. The check valve serves to prevent fluid flow in the direction opposite to the conveying direction. The check valve is biased in the closed position in the direction opposite to the conveying direction. According to the inventive method, the check valve opens at a lower pressure than the auxiliary valve. This is associated with the advantages described for the high-pressure cleaning device. The method according to the invention can be further developed by adding the optional features described above for the high-pressure cleaning device. This is associated with the respective advantages mentioned above. Exemplary embodiments of the invention are explained below with reference to the drawings. The drawings show: Fig. 1 a schematic representation of a high-pressure cleaning device with a start valve in the main line in an operating state in which the high-pressure pump is not delivering any liquid and the return line is closed not by the start valve but by the auxiliary valve; Fig. 2 a schematic representation of the high-pressure cleaning device from Fig. 1 in an operating state in which the high-pressure pump delivers air through the open check valve in the main line to the outlet opening, while the start valve is open and the auxiliary valve is closed; Fig. 3 a schematic representation of the high-pressure cleaning device from Fig.1 in an operating state in which the high-pressure pump delivers liquid such that the volume flow of the liquid delivered through the start valve is below the start volume threshold, but the pressure of the liquid in the return line is sufficient to open the auxiliary valve, Fig. 4 a schematic representation of the high-pressure cleaning device from Fig. 1 in an operating state in which the high-pressure pump delivers liquid with a volume flow through the start valve above the start volume threshold, so that the start valve closes the return line and the auxiliary valve is closed and Fig.5 A schematic representation of a high-pressure cleaning device in an alternative design with a start valve in the return line in an operating state in which the high-pressure pump delivers liquid with a volume flow through the start valve above the start volume threshold, so that the start valve closes the return line and the auxiliary valve is closed. Fig. 1 shows a schematic representation of a high-pressure cleaning device 1. The high-pressure cleaning device 1 comprises a pump unit 16 and a spray unit 11. The pump unit 16 and the dispensing unit 11 are fluidically connected to each other via a main line 5. In the exemplary embodiment, the dispensing unit 11 comprises a gun (not shown). However, it is also possible for the dispensing unit to comprise a gun and a lance. The high-pressure cleaning device 1 includes a connection 2 for a liquid source. In the exemplary embodiment, the liquid source is an external liquid source. The external liquid source can, for example, be a domestic water supply. However, it is also possible for the liquid source to be an integral part of the high-pressure cleaning device. The high-pressure cleaning device 1 includes a spray nozzle 6. The high-pressure cleaning device 1 includes the main line 5. The main line 5 of the high-pressure cleaning device 1 fluidically connects the port 2 to the spray nozzle 6. The port 2 is located on the pump unit 16. The spray nozzle 6 is located on the spray unit 11. In the exemplary embodiment, the spray nozzle 6 is located on the spray unit 11, which is designed as a gun. However, it can also be provided that the spray nozzle 6 is located on a lance of the spray unit 11, which may be replaceable.The high-pressure cleaning device 1 comprises a high-pressure pump 3. The high-pressure pump 3 is part of the pump unit 18. The high-pressure pump 3 is used to pressurize liquid in the high-pressure cleaning device 1, particularly in the pump unit 18. The liquid is, in particular, water, or more specifically, a mixture of water and an additive. The additive is, in particular, a cleaning agent solution, especially a soap solution. The cleaning agent is, in particular, liquid. The high-pressure pump 3 can pressurize the liquid to a pressure of at least 10 bar, in particular at least 15 bar, in particular at least 30 bar, and in particular at least 100 bar. In particular, the high-pressure pump 3 can pressurize the liquid to a maximum pressure of 600 bar, in particular at most 500 bar. The high-pressure pump 3 comprises at least one piston (not shown).At least one piston can be moved back and forth to generate pressure on the liquid. A high-pressure pump typically comprises three pistons. By means of the high-pressure pump 3, liquid can be pumped through the main line 5 from the connection 2 to the spray opening 6, in particular in a pumping direction 50. The pumping direction 50 is determined by the piping system of the high-pressure cleaning device 1. The pumping direction 50 is the direction in which a fluid, in particular the liquid, flows due to the piping layout and the action of the high-pressure pump 3. The pumping direction 50 can point in different directions in different sections of the piping system. The liquid source supplies liquid to the main line 5. The high-pressure pump 3 is located in the main line 5. The main line 5 has a suction chamber 9 and a pressure chamber 10. The high-pressure pump 3 is located between the suction chamber 9 and the pressure chamber 10 of the main line 5. The main line 5 has the suction chamber 9 between the connection 2 and the high-pressure pump 3. The main line 5 has the pressure chamber 10 between the high-pressure pump 3 and the discharge opening 6. In the exemplary embodiments, the suction chamber 9 is formed by a section of the main line 5 between the connection 2 and the high-pressure pump 3. In the exemplary embodiments, the pressure chamber 10 is formed by a section of the main line 5 between the high-pressure pump 3 and the discharge opening 6. The high-pressure pump 3 pumps liquid from the suction chamber 9 to the pressure chamber 10. The pressure in the pressure chamber 10 is higher than in the suction chamber 9, particularly during operation of the high-pressure pump 3.The suction chamber 9 and the pressure chamber 10 are components of the main line 5. Downstream of the high-pressure pump 3, the pressure in the main line 5 is higher than upstream of the high-pressure pump 3 when the high-pressure pump 3 is operating. In the suction chamber 9, the delivery direction 50 runs from the connection 2 towards the high-pressure pump 3. In the pressure chamber 10, the delivery direction 50 runs from the high-pressure pump 3 towards the discharge opening 6. The high-pressure pump 3 is arranged in the pump unit 16. The high-pressure cleaner 1 has a motor 4 to drive the high-pressure pump 3. The motor 4 is arranged in the pump unit 16. The motor 4 can be a brushless DC motor. A brushless DC motor is also referred to as an EC motor. The motor 4 can also be a universal motor. In the exemplary embodiment, the motor 4 is an induction motor. The induction motor in the exemplary embodiment is operated with alternating current. The voltage source can be provided, for example, by the mains voltage. If battery or accumulator operation is provided, the motor can also be a brushless DC motor. In this case, the battery can be integrated into the high-pressure cleaner 1. In particular, the pump unit 18 can then be integrated into the handheld spray unit 11.In this case, the entire high-pressure cleaning device 1 is portable and can be operated by hand. In particular, the pump unit and the spray unit are integrally designed. In particular, the pump unit and the spray unit are arranged in a common housing. In particular, the pump unit and the spray unit are rigidly connected to each other, specifically not via a flexible hose. In particular, the main line 5 is arranged in a single housing. The high-pressure cleaning device 1 includes a main line valve 8. The main line valve 8 is arranged in the main line 5. The main line valve 8 has two valve states: a closed state and an open state. In the open state, the main line valve 8 allows liquid to flow through the main line 5. In the closed state, the main line valve 8 prevents liquid from flowing through the main line 5. In the open state of the main line valve 8, liquid can be sprayed out of the spray opening 6. In the closed state of the main line valve 8, no liquid is sprayed out of the spray opening 6. In the exemplary embodiments, the main line valve 8 is arranged in the spray unit 11. In the exemplary embodiments, the main line valve 8 is arranged between the high-pressure pump 3 and the spray opening 6. In the embodiment shown in Figures 1, 2, 3 to 4, the high-pressure cleaning device 1 includes a shut-off device 7. Such a shut-off device can also be provided in the embodiment shown in Figure 5. It is also possible that the shut-off device 7 is omitted in the embodiment shown in Figures 1, 2, 3 to 4. In the embodiment shown in Figures 1 to 54, the high-pressure cleaning device 1 is designed such that the shut-off device 7, based on the pressure present in the pressure chamber 10, causes the motor 4 to be in the off state when the pressure in the pressure chamber corresponds to at least a certain pressure threshold. Motor 4 has a switch 18. The switch 18 is used to switch motor 4 between the on and off states. The shut-off device 7 has an actuating element 19. The high-pressure cleaning device 1 is designed such that the liquid in the pressure chamber 10 acts on the actuating element 19 of the shut-off device 7 in such a way that the actuating element 19 actuates the switch 18 of motor 4 so that motor 4 is in the off state when the pressure in the pressure chamber 10 is at least equal to the pressure threshold. Figure 1 shows a pressure relief line 36. The pressure relief line 36 connects the pressure chamber 10 fluidically to the suction chamber 9. The pressure relief line 36 allows for a further fluidic connection between the suction chamber 9 and the pressure chamber 10, separate from the fluidic connection between the suction chamber 9 and the pressure chamber 10 via the high-pressure pump 3. The pressure relief line 36 can be closed or open. A pressure relief valve 80 is arranged in the pressure relief line 36. The pressure relief valve 80 is designed to open when the pressure in the pressure chamber 10 is at least equal to the pressure threshold value. The high-pressure cleaning device 1 is designed such that a fluidic connection exists between the pressure chamber 10 and the suction chamber 9 when the pressure in the pressure chamber 10 corresponds to a minimum start pressure value. The start pressure value is lower than the pressure threshold value. In the exemplary embodiment, the high-pressure cleaning device 1 has a return line 12. The return line 12 can fluidly connect the pressure chamber 10 to the suction chamber 9. The return line 12 allows for a further fluidic connection between the suction chamber 9 and the pressure chamber 10, separate from the fluidic connection between the suction chamber 9 and the pressure chamber 10 via the high-pressure pump 3 and separate from the pressure relief line 36. In the return line 12, the flow direction 50 runs from the pressure chamber 10 towards the suction chamber 9. The high-pressure cleaning device 1 includes a start valve 20. The high-pressure cleaning device 1 is designed such that the start valve 20 closes when a start volume threshold of the flow rate through the start valve 20 is reached or exceeded. In particular, when the start volume threshold of the flow rate through the start valve 20 is reached or exceeded, the pressure in the pressure chamber 10 corresponds at least to the start pressure value. When the start valve 20 is closed, no fluid, in particular no liquid, can flow from the pressure chamber 10 into the suction chamber 9 through the return line 12. In the embodiment according to Figures 1, 2, 3 to 4, the start valve 20 is arranged in the main line 5. In the embodiment according to Figure 5, the start valve 20 is arranged in the return line 12. In all embodiments, the start valve 20 is arranged downstream of the high-pressure pump 3. In the embodiment according to Fig. 1, Fig.In Figures 2, 3 to 4, the starting valve 20 is arranged downstream of the high-pressure pump 3 in the main line 5 and / or upstream of the return line 12 in the main line 5. Fluid pumped by the high-pressure pump 3 first encounters the starting valve 20 before it can enter the return line 12. The starting valve 20 is located outside the return line 12. In all embodiments, the starting valve 20 is biased in an open position. The starting valve 20 is biased in the direction opposite to the pumping direction 50. The main line 5 is the line of the high-pressure cleaner 1 in the area between the high-pressure pump 3 and the spray nozzle 6, in which the liquid travels the shortest path from the high-pressure pump 3 to the spray nozzle 6. Branch lines from the main line 5, in which liquid may first enter the branch and then flow back, are not part of the main line 5. The high-pressure cleaning device 1 according to Figs. 1, 2, 3 to 4 is designed such that, during operation of the high-pressure cleaning device 1, the liquid flows through the start valve 20 at a flow rate below the start volume threshold without any possibility of branching off from the high-pressure pump 3 to the start valve 20 in the main line 5. In particular, during operation of the high-pressure cleaning device 1, the liquid flows through the start valve 20 regardless of the flow rate without any possibility of branching off from the high-pressure pump 3 to the start valve 20 in the main line 5. The starting valve 20 according to Figs. 1, 2, 3 to 4 has essentially three states. The states of the starting valve 20 are determined by the value of the volume flow rate through the starting valve 20. If the value of the volume flow rate of the liquid through the starting valve 20 is less than a quiescent volume threshold, the starting valve 20 is in a quiescent state. The quiescent state of the starting valve 20 is shown in Figs. 1 and 2. In the quiescent state, the pressure exerted by the liquid on the starting valve 20 is insufficient to move the starting valve 20 into another state. The starting valve 20 has a valve element 27. The valve element 27 is movably mounted in a valve housing of the starting valve. The valve element 27 is biased into the quiescent state position.It can be provided that the valve element 27 closes a valve seat of the main line, thus preventing the flow of liquid through the main line 5 from the valve element 27. In the exemplary embodiment, however, the starting valve 20 has a stop element 17. In the rest position, the valve element 27 rests against the stop element 17. The valve element 27 is biased towards the stop element 17. When the volume flow through the starting valve 20 is less than the quiescent volume threshold, the valve element 27 rests against the stop element 17. In particular, the valve element 27 rests against the stop element 17 when the valve element 27 is in a state unloaded by the liquid. In the exemplary embodiment according to Figs. 1, 2, 3 to 4, the starting valve 20 is designed such that liquid can pass through the starting valve 20 in the rest mode.For this purpose, a gap is provided between the valve element 27 and the valve housing when the valve element 27 is attached to the stop element 17. Fig. 3 shows the start valve 20 in a start mode. In start mode, liquid is pumped through the start valve 20 from the pressure chamber 10 of the main line 5 via the return line 12 back into the suction chamber 9. In start mode, the volume flow rate through the start valve 20 is at least equal to the static volume threshold. The volume flow rate of the liquid through the start valve 20 is less than a start volume threshold in start mode. The start volume threshold is greater than the static volume threshold. In the exemplary embodiment, the start valve 20 is designed such that, even if the volume flow rate through the start valve 20 is below the start volume threshold, it allows liquid to flow from the pressure chamber 10 into the return line 12. The starting valve 20 has a valve seat 35 as shown in Fig. 4. When the valve element 27 rests against the valve seat 35, the flow of liquid from the pressure chamber 10 of the main line 5 into the return line 12 is prevented. In starting mode, the valve element 27 is in a position in which it rests neither against the stop element 17 nor against the valve seat 35. The start valve 20 divides the pressure chamber 10 of the main line 5 into a pump section 14 and a spray section 15. The pump section 14 of the pressure chamber 10 of the main line 5 extends from the high-pressure pump 2 to the start valve 20. The spray section 15 of the pressure chamber 10 of the main line 5 extends from the start valve 20 to the spray opening 6. In the start mode of the start valve 20, fluid can flow through the start valve 20 both from the pump section 14 into the spray section 15 and from the pump section 14 into the return line 12. The volume flow rate, which determines the position of the valve element 27 in the start valve 20, is almost unaffected by the partial diversion of the volume flow into the return line 12 that occurs only after the valve element 27.The size of the volume flow that determines the position of the valve element 27 in the starting valve 20 is almost unaffected by the partial division of the volume flow, which only occurs after the valve element 27, into a portion of the volume flow that flows into the spray section 15 and another portion of the volume flow that flows into the return line. The starting valve 20 has an inlet 23. The inlet 23 of the starting valve 20 is connected to the main line 5. The inlet 23 of the starting valve 20 is connected to the pump section 14 of the pressure chamber 10 of the main line 5. The starting valve 20 has a return outlet 25. The return outlet 25 of the starting valve 20 is connected to the return line 12. The starting valve 20 has a main line outlet 26. The main line outlet 26 is connected to the main line 5. The main line outlet 26 is connected to the spray section 15 of the pressure chamber 10 of the main line 5. The return line 12 has an inlet 13. The valve seat 35 of the starting valve 20 is located at the inlet 13 of the return line 12. The inlet 13 of the return line 12 coincides with the return outlet 25 of the starting valve 20. In the start mode of the start valve 20, fluid can flow from the inlet 23 of the start valve 20 to both the return outlet 25 and the main line outlet 26. Fig. 4 shows the start valve 20 in a closed mode. In the embodiment shown in Figs. 1, 2, 3 to 4, the start valve 20 is designed such that, when the volume flow through the start valve 20 is at least equal to the start volume threshold, it prevents the flow of liquid from the pressure chamber 10 into the return line 12. When the volume flow through the start valve is at least equal to the start volume threshold, the start valve 20 closes the return outlet 25. In the closed mode of the start valve 20, the start valve element 27 rests against the start valve seat 35. The start valve 20 is designed to allow a direct flow of liquid from the pump section 14 to the spray section 15 when the volume flow rate through the start valve 20 is at least equal to the start volume threshold. In particular, in the closed mode, a loss-free flow of liquid from the pump section 14 to the spray section 15 through the start valve 20 is possible. In the closed mode of the start valve 20, the liquid flows directly from the inlet 23 of the start valve 20 to the main line outlet 26 of the start valve 20. In the closed mode of the start valve 20, the liquid pumped by the high-pressure pump 3 flows directly from the pump section 14 to the spray section 15 without passing through the return line 12. The closed mode of the start valve 20 is also referred to as the operating mode. In the embodiment shown in Figures 1, 2, 3 to 4, the starting valve element 27 is arranged entirely within the main line 5, and in particular entirely within the pressure chamber 10. The starting valve element 27 is arranged entirely outside the return line 12. In particular, the starting valve seat 35 is formed at an inlet 13 of the return line 12. In particular, the inlet 13 of the return line 12 is formed by the return outlet 25 of the starting valve 20. In all embodiments, the high-pressure cleaning device 1 includes a check valve 60. The check valve 60 serves to prevent a fluid flow, in particular a liquid flow, in the direction opposite to the conveying direction 50. In a closed state, the check valve 60 is biased in the direction opposite to the conveying direction 50. The check valve 60 is arranged in the pressure chamber 10. The check valve 60 is arranged downstream of the high-pressure pump 3. The check valve 60 is arranged downstream of the return line 12. In the embodiment according to Figs. 1, 2, 3 to 4, the check valve 60 is arranged downstream of the start valve 20. In this embodiment, the check valve 60 is arranged upstream of the shut-off device 7 in the pressure chamber 10. In the embodiment according to Figs. 1, 2, 3 to 4, the check valve 60 is arranged downstream of the start valve 20.The starting valve 20 is located in the main line 5 between the high-pressure pump 3 and the check valve 60. Because the shut-off device 7 is located between the check valve 60 and the main line valve 8, the pressure on the shut-off device 7 can only rise, not fall, as long as the motor 4 is running to drive the high-pressure pump 3 and the main line valve 8 is closed. This also ensures that the pressure on the pressure relief valve 80 can only rise as long as the motor 4 is running to drive the high-pressure pump 3 and the main line valve 8 is closed. This ensures that the pressure in the pressure chamber 10 exceeds the pressure threshold and the shut-off device 7 switches the motor 4 off. It also ensures that the pressure in the pressure chamber 10 exceeds the pressure threshold and the pressure relief valve 80 opens. In the valve housing of the starting valve 20, the starting valve element 27 is movable in a direction of movement 49. The liquid, pumped by the high-pressure pump 3 from the connection 2 to the spray opening 6 through the main line 5, encounters the starting valve 20 in the main line 5 in a flow direction 51, specifically the starting valve element 27 of the starting valve 20. The flow direction 51 is the direction in which the liquid flows into the starting valve 20 through the inlet 23 of the starting valve 20. The direction of movement 49 of the valve element 27 is in the direction of the flow direction 51. The valve element 27 is movable in the flow direction 51 to close the valve seat 35 of the starting valve 20. By moving the valve element 27 in the flow direction 51, the valve seat 35, located at the inlet 13 of the return line 12, can be closed. The starting valve element 27 is biased away from the inlet 13 of the return line 12. The starting valve element 27 is biased against the direction of movement 49. The stop element 17 limits movement of the starting valve element 27 away from the return line 12. The stop element 17 limits movement of the valve element 27 against the flow direction 51. The stop element 17 limits movement of the starting valve element 27 against the direction of movement 49. In all embodiments, the high-pressure cleaning device 1 includes an auxiliary valve 40, which is separate from the starting valve 20. The auxiliary valve 40 serves to interrupt the fluidic connection between the pressure chamber 10 and the suction chamber 9, which is possible due to the return line 12. The auxiliary valve 40 is biased in a closed position in the direction opposite to the conveying direction 50. The high-pressure cleaning device 1 is designed such that the check valve 60 opens at a lower pressure than the auxiliary valve 40. An auxiliary valve opening pressure is required to open the auxiliary valve 40. A check valve opening pressure is required to open the check valve 60. The check valve opening pressure is lower than the auxiliary valve opening pressure. In particular, the check valve opening pressure is 50% to 99%, more specifically 60% to 95%, and more specifically 70% to 90% of the auxiliary valve opening pressure. To open the auxiliary valve 40, a pressure differential is required in all embodiments between the pressure in the area immediately adjacent to the auxiliary valve 40 upstream and the pressure in the area of ​​the return line 12 immediately adjacent to the auxiliary valve 40 downstream. To open the check valve 60, a pressure differential is required between the area in the pressure chamber 10 immediately adjacent to the check valve 60 upstream and the area in the pressure chamber 10 immediately adjacent to the check valve 60 downstream. The pressure differential of the check valve is smaller than the pressure differential of the auxiliary valve. In particular, the pressure differential of the check valve is 50% to 99%, more specifically 60% to 95%, and more specifically 70% to 90% of the pressure differential of the auxiliary valve. To close the starting valve 20, a starting pressure differential is required between the pressure upstream of the starting valve 20 and the pressure downstream of the starting valve 20, in particular the pressure in the return line 12 downstream of the starting valve 20. The auxiliary valve pressure differential is smaller than the starting pressure differential. During the starting phase of the high-pressure pump 3, and in particular of the motor 4, the auxiliary valve 40 opens before the starting valve 20 closes. The check valve 60 is biased into the closed position by a return force. The auxiliary valve 40 is biased into the closed position by an auxiliary valve force. A fluid, in particular a liquid and / or air, can act on the check valve 60 with a return cross-sectional area, in particular a hydraulically effective one. A fluid, in particular a liquid and / or air, can act on the auxiliary valve 20 with an auxiliary valve cross-sectional area, in particular a hydraulically effective one. In particular, the return force, the return cross-sectional area, the auxiliary valve force, and the auxiliary valve cross-sectional area are coordinated such that the check valve 60 opens at a lower pressure, in particular a lower differential pressure, in particular a lower opening pressure, than the auxiliary valve 20.In particular, the check valve restoring force, the check valve cross-sectional area, the auxiliary valve force and the auxiliary valve cross-sectional area are coordinated such that the check valve pressure difference is smaller than the auxiliary valve pressure difference. In all embodiments, the auxiliary valve 40 is arranged in the return line 12. In particular, the auxiliary valve 40 is arranged completely outside the main line 5, especially the pressure chamber 10. The auxiliary valve 40 comprises an auxiliary valve element 41 and an auxiliary valve seat 43. The auxiliary valve element 41 is movable within the auxiliary valve 40. The auxiliary valve element 41 can be used to close the auxiliary valve seat 43. This interrupts the fluidic connection between the pressure chamber 10 and the suction chamber 9 via the return line 12. In particular, the auxiliary valve 40 does not allow air to pass through when closed. The auxiliary valve 40 includes an auxiliary valve spring 42. The auxiliary valve spring 42 biases the auxiliary valve 40 into the closed position. The auxiliary valve spring 42 biases the auxiliary valve element 41 into the auxiliary valve seat 43. The auxiliary valve spring 42 provides the auxiliary valve force. The additional valve element 41 is arranged in the return line 12, in particular completely outside the main line 5, in particular completely outside the pressure chamber 10. In all embodiments, the auxiliary valve 40 is arranged downstream of the starting valve 20. However, it is also possible for the auxiliary valve 40 to be arranged upstream of the starting valve 20. This applies if the starting valve 20 is located in the return line 12. In all embodiments, the check valve 60 comprises a check valve element 61 and a check valve seat 63. The check valve element 61 is movable within the check valve 60. The check valve element 61 can be used to close the check valve seat 63. In particular, the check valve 60 does not allow air to pass through when closed. The check valve 60 includes a check valve spring 62. The check valve spring 62 biases the check valve 60 into the closed position. The check valve spring 62 biases the auxiliary valve element 61 into the check valve seat 63. The check valve spring 62 generates the check valve force. In the exemplary embodiments, the auxiliary valve force is greater than the check valve force. However, it is also possible for the auxiliary valve force and the check valve force to be equal, or for the auxiliary valve force to be less than the check valve force. In the exemplary embodiments, the check valve cross-sectional area is larger than the auxiliary valve cross-sectional area. However, it is also possible for the check valve cross-sectional area and the auxiliary valve cross-sectional area to be the same size, or for the check valve cross-sectional area to be smaller than the auxiliary valve cross-sectional area. The auxiliary valve element 41 and the starting valve element 27 are designed separately from each other. The auxiliary valve element 41 and the starting valve element 27 are arranged spatially separated from each other. Particularly after the motor 4 is switched off by actuating the switch 18 of the shutdown device 7 shown in Figures 1, 2, 3 to 4, following the closing of the main line valve 8, a high pressure prevails in the pressure chamber 10. This pressure is partially reduced by opening the pressure relief valve 80. This pressure reduction opens the start valve 20, allowing a backflow of fluid from the pressure chamber 10, especially from the pump section 14 of the pressure chamber 10, into the suction chamber 9. The start valve 20 is then either in the standby or start mode. When the motor 4 is switched on again, the pump 3 has to operate against a much lower pressure due to the open start valve 20 than if the start valve 20 were not present. Due to the arrangement of the start valve 20 in the main line 5, the flow rate that triggers the switching of the start valve 20 is clearly defined. The check valve 60 opens at a lower pressure than the auxiliary valve 40. If, when the motor 4 is restarted or when it is switched on for the first time after the high-pressure cleaner 1 has been put into operation, there is still air in the high-pressure pump 3, this air can be expelled from the high-pressure cleaner 1 through the main line 5, and in particular through the check valve 60, in all embodiments, thanks to the auxiliary valve 40. Specifically, the air exits through the spray nozzle 6. This situation is illustrated in Fig. 2 as an example for all embodiments. The check valve 60 is open and the auxiliary valve 40 is closed. The air leaves the high-pressure cleaner 1 and, due to the auxiliary valve 40, is not recirculated through the return line 12. The high-pressure pump 3 then delivers liquid. As shown in Fig. 3, the pressure in the return line 12 is then sufficient to open the auxiliary valve 40. However, the pressure in the pressure chamber 10 is not yet sufficient to open the start valve 20. As described, the high-pressure pump 3 can then start without significant back pressure and reach its operating speed. Only then is the pressure, or rather the volume flow of the liquid in the pressure chamber 10, sufficient to close the start valve 20, as shown in Fig. 4. The auxiliary valve 40 then also closes. The high-pressure cleaning device 1 has then reached its desired operating state. The embodiment shown in Fig. 5 differs from the embodiment shown in Figs. 1, 2, 3 to 4 only in that no pressure relief line 36 is provided and that the starting valve 20 is arranged outside the main line 5, in particular outside the pressure chamber 10. Otherwise, the description of the embodiment shown in Figs. 1, 2, 3 to 4 also applies to the embodiment shown in Fig. 5.

Claims

High-pressure cleaning device comprising: - a high-pressure pump (3) for conveying liquid in a conveying direction (50) and - a main line (5) through which liquid can be conveyed by means of the high-pressure pump (3), wherein the main line (5) has a suction chamber (9) upstream of the high-pressure pump (3), wherein the main line (5) has a pressure chamber (10) downstream of the high-pressure pump (3), wherein a return line (12) for fluidic connection between the pressure chamber (10) and the suction chamber (9) is arranged, wherein the high-pressure cleaning device (1) comprises a start valve (20) for preventing a liquid flow through the return line (12), wherein the start valve (20) is biased to an open state against the conveying direction (50), wherein the high-pressure cleaning device (1) comprises a check valve (60) for preventing a liquid flow against the conveying direction (50),wherein the check valve (60) is biased into a closed state against the conveying direction (50), wherein the check valve (60) is arranged in the pressure chamber (10) downstream of the return line (12), characterized in that the high-pressure cleaning device (1) comprises an auxiliary valve (40) designed separately from the start valve (20) for interrupting the fluidic connection between the pressure chamber (10) and the suction chamber (9) through the return line (12), that the auxiliary valve (40) is biased into a closed state against the conveying direction (50), and that the high-pressure cleaning device (1) is designed such that the check valve (60) opens at a lower pressure than the auxiliary valve (40). High-pressure cleaning device according to claim 1, characterized in that the check valve (60) is biased into the closed state of the check valve (60) by a check return force, that the auxiliary valve (40) is biased into the closed state of the auxiliary valve (40) by an auxiliary valve force, that a fluid with a check cross-sectional area can act on the check valve (60), that a fluid with an auxiliary valve cross-sectional area can act on the auxiliary valve (40), and that the check return force, the check cross-sectional area, the auxiliary valve force and the auxiliary valve cross-sectional area are coordinated such that the check valve (60) opens at a lower pressure than the auxiliary valve (40). High-pressure cleaning device according to claim 2, characterized in that the check valve (60) has a check spring (62) which causes the check return force, and / or that the auxiliary valve (40) has an auxiliary valve spring (42) which causes the auxiliary valve force. High-pressure cleaning device according to one of claims 1 to 3, characterized in that the start valve (20) has a start valve element (27), and that the start valve element (27) is designed separately from an additional valve element (41) of the additional valve (40). High-pressure cleaning device according to one of claims 1 to 4, characterized in that the start valve (20) is arranged in the main line (5) downstream of the high-pressure pump (3). High-pressure cleaning device according to claim 5, characterized in that the start valve element (27) is arranged completely in the main line (5), in particular the pressure chamber (10), in particular that the start valve element (27) is arranged completely outside the return line (12), and in particular that a start valve seat (35) of the start valve (20) is formed at an inlet (13) of the return line (12). High-pressure cleaning device according to one of claims 1 to 6, characterized in that the additional valve (40) is arranged in the return line (12). High-pressure cleaning device according to one of claims 1 to 7, characterized in that the auxiliary valve (40) is arranged downstream of the start valve (20). High-pressure cleaning device according to one of claims 1 to 8, characterized in that a starting pressure differential between the area upstream of the starting valve (20) and the area downstream of the starting valve (20), in particular in the return line (12), is required to close the starting valve (20), that an additional valve pressure differential between the area upstream of the additional valve (40) and the area downstream of the additional valve (40), in particular in the return line (12), is required to open the additional valve (40), and that the additional valve pressure differential is smaller than the starting pressure differential. Method for operating a high-pressure cleaning device, wherein the high-pressure cleaning device (1) comprises a high-pressure pump (3) for conveying liquid in a conveying direction (50) and a main line (5) through which liquid can be conveyed by means of the high-pressure pump (3), wherein the main line (5) has a suction chamber (9) upstream of the high-pressure pump (3), wherein the main line (5) has a pressure chamber (10) downstream of the high-pressure pump (3), wherein a return line (12) for fluidic connection between the pressure chamber (10) and the suction chamber (9) is arranged, wherein the high-pressure cleaning device (1) comprises a starting valve (20) for interrupting a liquid flow through the return line (12), wherein the starting valve (20) is biased to an open state against the conveying direction (50),wherein the high-pressure cleaning device (1) comprises a check valve (60) for preventing a fluid flow against the direction of delivery (50), wherein the check valve (60) is biased into a closed state against the direction of delivery (50), wherein the check valve (60) is arranged in the pressure chamber (10) downstream of the return line (12), characterized in that the high-pressure cleaning device (1) comprises an auxiliary valve (40) designed separately from the start valve (20) for interrupting the fluidic connection between the pressure chamber (10) and the suction chamber (9) through the return line (12), that the auxiliary valve (40) is biased into a closed state against the direction of delivery (50), and that the check valve (60) opens at a lower pressure than the auxiliary valve (40).

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