Hydraulic system and passenger restraint system

Abstract

The present invention relates to a hydraulic system 1 for a passenger restraint device 3, wherein the hydraulic system 1 has a hydraulic pump 6 and a hydraulic section 5 with a hydraulic accumulator 9, a valve arrangement 8 and a hydraulic cylinder unit 10 with a piston 11. The valve arrangement 8 is connected to the hydraulic pump 6, the hydraulic accumulator 9 and the hydraulic cylinder unit 10. The piston 11 is movable between an open position and a first closed position. The hydraulic pump 6 is designed to apply pressure to the hydraulic cylinder unit 10 so that the piston 11 moves from the first closed position into the open position. The hydraulic accumulator 9 is designed to apply pressure to the hydraulic cylinder unit 10 so that the piston 11 moves from the open position into the first closed position.The valve arrangement 8 can be switched at least into a first switching position and a second switching position, wherein the pressure is applied to the hydraulic cylinder unit 10 by the hydraulic pump 6 in the first switching position with a first pressure stage and wherein the pressure is applied to the hydraulic cylinder unit 10 by the hydraulic pump 6 in the second switching position in a second pressure stage, wherein the second pressure stage is lower than the first pressure stage.

Description

[0001] The present invention relates to a hydraulic system for a passenger restraint device and to a passenger restraint system having at least one passenger restraint device with such a hydraulic system.

[0002] Such passenger restraint devices are used primarily for rides such as roller coasters, simulators, or other amusement devices. In these rides, passengers are sometimes subjected to considerable forces and acceleration. For safety reasons, passenger restraint devices are therefore provided to secure passengers to the passenger seating they are occupying. The passenger restraint device typically features a hydraulically operated restraint bar that can be extended and retracted. When the restraint bar is retracted, the passenger restraint device is closed, securing the passenger in the passenger seating. However, when the restraint bar is extended, the passenger restraint device is open, allowing passengers to enter and exit the passenger seating.

[0003] A hydraulic system is used to open and close the passenger restraint device. Such a hydraulic system typically comprises a hydraulic pump, a hydraulic accumulator, and a hydraulic cylinder unit with a piston. The piston is movably arranged within the hydraulic cylinder unit to adjust the passenger restraint device. To open the passenger restraint device, the piston is pressurized by the hydraulic pump. To close it, however, the piston is pressurized by the hydraulic accumulator.

[0004] Corresponding hydraulic systems are known from the state of the art, for example, from WO 2019 / 229183 A1, and typically feature predefined, for example, lockable, closing positions of the restraint bar. However, due to different sizes or body sizes of passengers, predefined closing positions can lead to insufficient or excessive restraint of passengers. This leads to a lack of safety and discomfort for the passengers.

[0005] Furthermore, DE 10 2020 131 679 A1, DE 10 2020 125 192 A1 and DE 10 2019 216 083 A1 as well as DE 25 18 715 A1 are part of the state of the art.

[0006] A passenger restraint device within the meaning of the present invention is understood to be a restraint device for passengers in 4D cinemas, simulators, VR rides, and amusement rides such as roller coasters or carousels. Therefore, the object of the present invention is to provide an improved hydraulic system that increases the degree of automation of a passenger restraint device, as well as the safety and well-being of passengers.

[0007] The object is achieved with a hydraulic system according to claim 1 and a passenger restraint system according to claim 14. Advantageous further developments are described in the dependent claims.

[0008] The hydraulic system according to the invention for a passenger restraint device has a hydraulic pump and a hydraulic section. The hydraulic section has a hydraulic accumulator, a valve arrangement, and a hydraulic cylinder unit with a piston. The valve arrangement is connected to the hydraulic pump, the hydraulic accumulator, and the hydraulic cylinder unit. The piston is movable between an open position and a first closed position. The hydraulic pump is designed to apply pressure to the hydraulic cylinder unit, so that the piston moves from the first closed position to the open position. The hydraulic accumulator is designed to apply pressure to the hydraulic cylinder unit, so that the piston moves from the open position to the first closed position. The valve arrangement can be switched into at least a first switching position and a second switching position.The hydraulic cylinder unit is pressurized by the hydraulic pump in the first switching position with a first pressure level. The hydraulic cylinder unit is pressurized by the hydraulic pump in the second switching position with a second pressure level, whereby the second pressure level is lower than the first pressure level.

[0009] In other words, the hydraulic pump opens a restraint bar of the passenger restraint device, and the hydraulic accumulator closes the restraint bar to the first closed position. The opening position of the piston corresponds to the open position of the passenger restraint device, allowing a passenger to get in and out of it. The first closed position of the piston corresponds to the position of the passenger restraint device in which the passenger is securely fastened with the largest possible body circumference. The valve arrangement can switch between two pressure stages by switching between the switching positions, so that the hydraulic cylinder unit is subjected to a higher pressure when the restraint bar is opened than when the restraint bar is closed.

[0010] This advantageously allows the passenger to manually adjust the restraint bar when the hydraulic cylinder unit is subjected to the second pressure stage. However, if the hydraulic cylinder unit is subjected to the first pressure stage, the restraint bar cannot be adjusted by the passenger. The manual adjustability of the restraint bar in the second switching position allows the passenger to adjust the position of the restraint bar according to their height and / or body size, ensuring that the passenger is firmly and securely restrained by the passenger restraint device. This further increases passenger safety.

[0011] Furthermore, the hydraulic accumulator can advantageously be operated at a lower pressure than the pressure of the hydraulic pump required to close the restraint bar. Because the hydraulic cylinder unit is subjected to the higher pressure of the hydraulic pump when the restraint bar is opened, hydraulic fluid is returned to the hydraulic accumulator when the piston is moved to the open position. This recharges the hydraulic accumulator, so that the full accumulator pressure is available for closing the restraint bar.

[0012] The hydraulic pump is preferably designed as a fixed-displacement pump, meaning its output is constant and not regulated. Compared to a variable-displacement pump, whose output can be changed, the manufacturing costs of the hydraulic system can be reduced. To prevent overpressure or damaging pressure peaks in the hydraulic system, a safety pressure relief valve is provided between the hydraulic pump and the hydraulic cylinder unit.

[0013] It is advantageous if the valve arrangement has a first pressure relief valve and a first directional control valve, wherein the first directional control valve blocks a flow path to the first pressure relief valve in the first switching position of the valve arrangement, and wherein the first directional control valve opens the flow path to the first pressure relief valve in the second switching position of the valve arrangement, wherein the first pressure relief valve is designed to set the second pressure stage. By means of the first pressure relief valve, the second pressure stage can advantageously be set such that it is lower than the first pressure stage. The first directional control valve advantageously enables the flow path to the first pressure relief valve to be blocked when the retaining bracket is opened, such that the hydraulic cylinder unit is subjected to the first pressure stage by the hydraulic pump.This prevents hydraulic fluid from flowing through the first pressure relief valve. When the piston is in the open position, the restraint bar can advantageously serve as a grab handle for passengers getting in and out, as it is held in place by the relatively high pressure in the first pressure stage.

[0014] In addition, the valve arrangement preferably has a second directional control valve and a second pressure relief valve, wherein the valve arrangement can be switched into a third switching position. The pressurization of the hydraulic cylinder unit by the hydraulic pump in the third switching position takes place with a third pressure stage in that the second directional control valve, in the third switching position of the valve arrangement, blocks the flow path to the first pressure relief valve and opens it to the second pressure relief valve, wherein the second pressure relief valve is designed to set the third pressure stage. This advantageously makes it possible to switch between the second and third pressure stages when the retaining bracket is closed. In the third pressure stage, the hydraulic system moves the piston from the open position to the first closed position with the aid of the hydraulic accumulator.When the first closed position is reached, the valve assembly switches to the second switching position, thus enabling the second pressure stage, so that the restraint bar of the passenger restraint device can now be manually adjusted. This advantageously further increases the degree of automation and enables an improved position of the restraint bar for secure passenger restraint.

[0015] Preferably, the hydraulic accumulator is configured to apply a fourth pressure level to the hydraulic cylinder unit, wherein the fourth pressure level is lower than the first pressure level. In other words, the operating pressure of the hydraulic accumulator is lower than the operating pressure of the hydraulic pump. As a result, the hydraulic accumulator is advantageously charged by the fluid displaced from the hydraulic cylinder unit when the piston moves from the closed position to the open position.

[0016] In a further development, the fourth pressure stage of the hydraulic accumulator is lower than the second pressure stage. The pressure difference between the fourth and second pressure stages is so small that the pressure difference can be overcome by the passenger. The passenger pulls the restraint bar toward them, exerting additional pressure on the hydraulic cylinder unit to the already existing fourth pressure stage and against the second pressure stage. The additional pressure and the fourth pressure stage together exceed the second pressure stage set on the first pressure relief valve, allowing manual closing.

[0017] Preferably, the fourth pressure stage is higher than the third pressure stage. The pressure difference between the fourth and third pressure stages is so small that the closing movement of the restraint bar can be adjusted via the third pressure stage.

[0018] The hydraulic cylinder unit is preferably designed as a differential cylinder, and the hydraulic cylinder unit has a hydraulic cylinder housing with an interior space, wherein the piston is movably arranged in the interior of the hydraulic cylinder housing. The piston divides the interior of the hydraulic cylinder housing into a first working chamber and a second working chamber, wherein the first working chamber is connected to the hydraulic accumulator and the second working chamber is connected to the hydraulic pump. As a rule, the differential cylinder has a piston rod on one side of the piston surface. As a result, the entire piston surface acts on one side of the piston, and only the annular surface acts on the rod-side surface. The differential cylinder therefore has two different sized active surfaces. In this case, the rod-side surface faces the second working chamber, and the entire piston surface faces the first working chamber.Due to the larger effective area, the pressure in the hydraulic accumulator can be lowered, which advantageously results in a more compact design. The design as a differential cylinder allows the hydraulic cylinder unit to be more compact.

[0019] The valve arrangement preferably has a third directional control valve between the hydraulic cylinder unit and the hydraulic accumulator, wherein the third directional control valve is switchable between a through position and a blocking position, wherein the third directional control valve blocks the flow path from the hydraulic cylinder unit to the hydraulic accumulator in the blocking position, but opens the flow path from the hydraulic accumulator to the hydraulic cylinder unit. Advantageously, the third directional control valve is switched to the through position when the restraint bar is opened and to the blocking position when it is closed. When the restraint bar is in its final closed position, in which the passenger is secured, the fluid is trapped in the hydraulic device. Thus, the restraint bar cannot open while driving.

[0020] Preferably, the piston is manually movable from the first closed position to a second closed position, wherein the first closed position lies between the open position and the second closed position. The second closed position of the piston is variable and corresponds to the position of the passenger restraint device in which the passenger is securely secured according to their body size. Advantageously, the restraint bar moves automatically from the open position to the first closed position, so that the passenger can manually pull the restraint bar toward them until the restraint bar securely secures the passenger.

[0021] Preferably, the valve arrangement switches to the third switching position when the piston moves from the open position to the first closed position. As a result, the pressure of the hydraulic accumulator is greater than the third pressure level set by the second pressure relief valve, and the hydraulic system advantageously moves the piston automatically from the open position to the first closed position.

[0022] Preferably, the valve arrangement switches to the second switching position when the piston moves from the first closed position to the second closed position. As a result, the pressure of the hydraulic accumulator is lower than the second pressure level set by the first pressure relief valve, so that the piston can only be moved to the second closed position with additional manually applied pressure.

[0023] Preferably, the first closing position of the piston is adjustable. This advantageously allows the first closing position of the restraint bar to be adapted, for example, to country-specific body characteristics or for children's rides. Rides may also differ in loads, forces, or acceleration values, so a tighter restraint of passengers may be necessary.

[0024] In addition, the hydraulic section has a detection unit and a control unit connected to the detection unit, so that the first closing position of the piston can be adjusted in the control unit and / or the movement of the piston by the hydraulic accumulator from the

[0025] The valve arrangement can be switched from the first closed position to the first open position. This advantageously makes it possible to adjust the first closed position of the piston. The detection unit can, for example, have a piston position sensor and / or a time-out device. The piston position sensor detects the position of the piston in the hydraulic cylinder unit so that, for example, when the first closed position is reached, the valve arrangement switches from the third to the second switching position. The time-out device detects the time required for the piston to be moved to the first closed position and, once the time has elapsed, switches the valve arrangement from the third to the second switching position.

[0026] Preferably, the hydraulic section is a first hydraulic section, and the hydraulic system comprises at least one second hydraulic section identical to the first hydraulic section. Preferably, the first hydraulic section is connected to the second hydraulic section such that the piston of the first hydraulic section is movable independently of a piston of the second hydraulic section, wherein the at least one second hydraulic section is connected to the hydraulic pump. This advantageously allows multiple passenger restraint devices to be operated with only one hydraulic pump. Ideally, all passenger restraint devices in a ride are operated with only one hydraulic pump. This leads to lower manufacturing and assembly costs. To prevent mutual interference between the individual hydraulic sections, each hydraulic section is provided with a check valve.This means, for example, that the restraint bars can be closed independently of one another.

[0027] The hydraulic system expediently has a tank so that hydraulic fluid flowing back from the hydraulic cylinder unit or hydraulic fluid flowing out via the pressure relief valves flows back into the tank. The hydraulic system preferably has a return channel connected to the tank for this purpose.

[0028] Preferably, the first, second, and / or third directional control valve is electrically controllable. This advantageously enables control via an electronic control unit.

[0029] It is also advantageous if the third-way valve can be operated both electrically and manually. In a ride with multiple cars, such as a roller coaster, the cars are usually only supplied with power in the station, for example, via a pantograph. When leaving the station, the car is de-energized, meaning the third-way valve cannot be operated electrically. If the car breaks down on the open track or in the event of a power failure, the third-way valve can be manually operated to open the restraint bar, allowing passengers to exit the car and the ride.

[0030] It is advantageous if the hydraulic system has a check valve between the hydraulic cylinder unit and the hydraulic pump, which blocks the flow path from the hydraulic cylinder unit to the hydraulic pump. In combination with the blocked first directional control valve, the hydraulic fluid is trapped in the hydraulic cylinder unit when the piston is in the open position. Thus, the restraint bar of the passenger restraint device can serve as an entry and / or exit aid, providing support for the passenger.

[0031] A passenger restraint system according to the invention comprises at least one passenger restraint device and a hydraulic system as described above. The passenger restraint system may comprise a plurality of passenger restraint devices that can be actuated via a hydraulic system, with each passenger restraint device then being assigned a hydraulic section.

[0032] The invention is described in more detail below with reference to the embodiments illustrated in the figures. These schematically show: Fig. 1 a hydraulic circuit diagram of a hydraulic system according to the invention; and Fig. 2 a passenger restraint system with a passenger restraint device and the hydraulic system.

[0033] An embodiment of the present invention will now be described with reference to the accompanying figures, wherein like reference numerals designate corresponding or identical elements in the figures.

[0034] Fig. 1 shows a hydraulic circuit diagram of a hydraulic system 1 for a passenger restraint device according to the present invention. Fig. 2 shows a passenger restraint system 2 with the passenger restraint device 3, which has a restraint bar 4 for securing a passenger in a passenger receptacle 5 occupied by him.

[0035] The hydraulic system 1 has a hydraulic pump 6, which in this case is designed as a fixed-displacement pump with a constant delivery rate. The hydraulic pump 6 can also be designed as a controlled variable-displacement pump with a variable delivery rate. The hydraulic system 1 has at least one hydraulic section 5; in this exemplary embodiment, there are three hydraulic sections 5. However, the number is not limited to this. Each hydraulic section 5 has a valve arrangement 8, a hydraulic accumulator 9, and a hydraulic cylinder unit 10 with a piston 11.

[0036] How Fig. 1 can be further removed, the hydraulic system 1 has a tank 22 and a return channel 23 connected to the tank 22. Returning hydraulic fluid flows from the second working chamber 16 of the hydraulic cylinder unit 10 via the return channel 23 back into the tank 22, as will be described in more detail below.

[0037] The three hydraulic sections 5 of the hydraulic system 1 are connected to the hydraulic pump 6 via a supply channel 25 and to the tank 22 via the return channel 23.

[0038] The hydraulic cylinder unit 10 has a hydraulic cylinder housing 12 with an interior space 13 in which the piston 11 is movable. The piston 11 has a piston rod 14, which is connected to the restraint bar 4 of the passenger restraint device 3 in order to open and close the passenger restraint device 3. The hydraulic cylinder unit 10 is designed as a differential cylinder. The piston 11 divides the interior space 13 into a first working chamber 15 and a second working chamber 16. The first working chamber 15 is connected to the hydraulic accumulator 9, and the second working chamber 16 is connected to the hydraulic pump 6.

[0039] The hydraulic pump 6 is designed to pressurize the second working chamber 16 of the hydraulic cylinder unit 10 in order to move the piston 11 from a first closed position to an open position. For this purpose, the second working chamber 16 is connected to the hydraulic pump 6 via a pressure line 28 branching off from the feed channel 25. As shown, a check valve 26 and an adjustable throttle valve 27 can be arranged in the pressure line 28 in order to regulate the inflowing quantity and to prevent backflow to the hydraulic pump 6. This prevents interactions between the hydraulic cylinder units 10 of the respective hydraulic section 5. Due to lines of different lengths between the hydraulic pump 6 and the respective hydraulic cylinder unit 10, pressure losses can occur along the feed channel 25.In order to apply the same pressure to all hydraulic cylinder units 10, the individual hydraulic sections 5 are hydraulically balanced with each other via the adjustable throttle valve 27.

[0040] The hydraulic accumulator 9, on the other hand, is designed to pressurize the first working chamber 15 of the hydraulic cylinder unit 10 in order to move the piston 11 from the open position to the first closed position. The open position of the piston 11 corresponds to the position of the extended restraint bar 4, and the passenger restraint device 3 is open, so that the passenger can enter and exit the passenger compartment 5. The first closed position of the piston 11 corresponds to the position of the restraint bar 4 retracted far enough that the passenger restraint device 3 is closed up to the largest possible body circumference of the passenger. In the open position, the piston 11 is fixed due to the relatively high pressure and can then also be used by the passenger as a grab handle.

[0041] Furthermore, the piston 11 can be manually moved into a second closed position. The first closed position lies between the open position and the second closed position. The second closed position of the piston 11 is variable and corresponds to the position of the passenger restraint device 3, in which the passenger is securely restrained according to their body size.

[0042] In order to move the piston 11 into the second closing position, the passenger pulls the restraint bar 4 from the first closing position towards him until the passenger is securely fixed.

[0043] The valve arrangement 8 can be switched into a first switching position, a second switching position, and a third switching position. For this purpose, the valve arrangement 8 has a first pressure relief valve 17, a first directional control valve 18, a second directional control valve 19, and a second pressure relief valve 20. The first directional control valve 18 and the second directional control valve 19 are arranged in a branch line 29, which branches off between the second working chamber 16 of the hydraulic cylinder unit 10 and the hydraulic pump 6 and is connected to the return channel 23. The first directional control valve 18 is connected to the pressure line 28 and the second directional control valve 19. The second directional control valve 19 is arranged downstream of the first directional control valve 18 and connects the first directional control valve 18 to the return channel 23 either via the first pressure relief valve 17 or via the second pressure relief valve 20 arranged parallel thereto.

[0044] In the first switching position of the valve assembly 8, the first directional control valve 18 blocks a flow path from the pressure channel 28 to the first pressure relief valve 17, and the hydraulic cylinder unit 10 is pressurized by the hydraulic pump 6 at a first pressure stage. This causes the piston 11 to move into the open position, and the retaining bar 4 opens.

[0045] In the second switching position of the valve arrangement 8, the first directional control valve 18 opens the flow path through the branch line 29, and the second directional control valve 19 connects the first directional control valve 18 to the first pressure relief valve 17, so that the hydraulic cylinder unit 10 is pressurized by the hydraulic pump 6 at a second pressure level. The first pressure relief valve 17 is designed to adjust the second pressure level. The pressure levels are selected such that the first pressure level of the hydraulic pump 6 is higher than the second pressure level of the first pressure relief valve 17. For example, the first pressure level can be 100 bar and the second pressure level 60 bar.

[0046] In the third switching position of the valve assembly 8, the second directional control valve 19 connects the first directional control valve 18 to the second pressure relief valve 20. In this switching position, the hydraulic cylinder unit 10 is pressurized by the hydraulic pump 6 at a third pressure level. The second pressure relief valve 20 is designed to set the third pressure level, which is lower than the second pressure level. The third pressure level can be 20 bar, for example. Thus, the valve assembly can switch between two different pressure levels when closing the passenger restraint device 3.

[0047] The valve arrangement 8 further comprises a third directional control valve 21, which is arranged between the first working chamber 15 of the hydraulic cylinder unit 10 and the hydraulic accumulator 9. The third directional control valve 21 can be switched between a through position and a blocking position. In the through position, the flow path between the first working chamber 15 and the hydraulic accumulator 9 is open in both directions. In the blocking position, however, the flow path from the first working chamber 15 to the hydraulic accumulator 9 is closed, but the flow path from the hydraulic accumulator 9 to the first working chamber 15 is open.

[0048] The hydraulic accumulator 9 is designed to apply a fourth pressure level to the hydraulic cylinder unit 10. The fourth pressure level is lower than the second pressure level, but higher than the third pressure level. The fourth pressure level can be, for example, 40 bar. When the hydraulic pump 6 applies the first pressure level to the hydraulic cylinder unit 10, so that the piston 11 moves toward the open position, the third directional control valve 21 is switched to the through position, so that the hydraulic fluid flows back into the hydraulic accumulator 9. This charges the hydraulic accumulator 9 to move the piston 11 back from the open position to the first closed position.

[0049] If, however, the piston 11 is in the open position, the valve arrangement 8 is switched to the first position, so that the first directional valve 18 blocks the branch line 29. This applies the first pressure stage to the hydraulic cylinder unit 10. Since the fourth pressure stage of the hydraulic accumulator 9 is significantly lower than the first pressure stage of the hydraulic pump 6, the passenger can support themselves or hold on to the restraint bar 4 of the passenger restraint device 3 and thus use it as an aid for getting in and out. The first pressure stage and fourth pressure stage are selected such that the sum of the fourth pressure stage and the additional pressure that the passenger exerts on the restraint bar 4 and thus on the piston 11 when getting in and out is less than the first pressure stage. As a result, the restraint bar 4 cannot be moved by the passenger contrary to the first pressure stage.

[0050] To move the piston 11 from the open position to the first closed position, the valve assembly 8 switches to the third switching position, so that the third pressure stage is present in the second working chamber 16 of the hydraulic cylinder unit 10. This enables a controlled or specifically adjusted closing movement of the retaining bar 4. When the piston 11 reaches the first closed position, the valve assembly 8 switches to the second switching position, so that the second pressure stage is present in the second working chamber 16.

[0051] Since the second pressure level is only slightly higher than the fourth pressure level of the hydraulic accumulator 9, the passenger can exert sufficient pressure on the piston 11 by pulling the restraint bar 4 toward the passenger, so that the sum of the fourth pressure level and the pressure exerted by the passenger is greater than the second pressure level set by the first pressure relief valve 17. Thus, the piston 11 can be manually adjusted to the second closed position.

[0052] The first, second, and third directional control valves 18, 19, 21 can each be electrically controlled. These can be controlled, for example, by an integrated control unit. The third directional control valve 21 can also be manually operated in order to manually open the retaining bracket 4 in the event of a power failure. The first, second, and third directional control valves 18, 19, 21 each have return springs that return the respective directional control valve to the rest position when the respective directional control valve is not electrically actuated and is therefore de-energized. The first directional control valve 18 is preloaded such that the branch line 29 is blocked. The third directional control valve 21 is preloaded in the above-described blocked position so that further closing of the retaining bracket 4 is possible, but opening of the retaining bracket 4 is prevented.

[0053] The hydraulic system 1 further includes a third pressure relief valve 24, which connects the supply channel 25 to the tank 22. The third pressure relief valve 24 is designed to adjust the first pressure level and prevent pressure peaks to prevent damage to the hydraulic system 1. The first pressure level can be 100 bar, for example.

[0054] Although the terms "first," "second," "third," and "fourth" are used herein to distinguish various components, these components are not intended to be limited by these terms. These terms are used only to distinguish the components from one another and do not dictate a specific order. Thus, for example, a first component described above could be referred to as a second component, and vice versa. LIST OF REFERENCE SYMBOLS 1 hydraulic system 2 Passenger restraint system 3 Passenger restraint device 4 restraint bars 5 Passenger accommodation 6 Hydraulic pump 5 Hydraulic section 8 Valve arrangement 9 hydraulic accumulators 10 Hydraulic cylinder unit 11 pistons 12 hydraulic cylinder housings 13 Interior 14 Piston rod 15 first workroom 16 second workroom 17 first pressure relief valve 18 first directional control valve 19 second directional control valve 20 second pressure relief valve 21 third-way valve 22 tanks 23 Return channel 24 third pressure relief valve 25 flow channel 26 Check valve 27 Throttle valve 28 pressure line 29 branch line

Claims

[1] Hydraulic system (1) for a passenger restraint device (3), wherein the hydraulic system (1) comprises a hydraulic pump (6) and a hydraulic section (5) with a hydraulic accumulator (9), a valve arrangement (8) and a hydraulic cylinder unit (10) with a piston (11), wherein the valve arrangement (8) is connected to the hydraulic pump (6), the hydraulic accumulator (9) and the hydraulic cylinder unit (10), wherein the piston (11) is movable between an opening position and a first closing position, wherein the hydraulic pump (6) is designed to pressurise the hydraulic cylinder unit (10) so that the piston (11) moves from the first closed position to the open position, wherein the hydraulic accumulator (9) is designed to apply pressure to the hydraulic cylinder unit (10) so that the piston (11) moves from the opening position to the first closing position, wherein the valve arrangement (8) is switchable into at least a first switching position and a second switching position, wherein the pressure on the hydraulic cylinder unit (10) by the hydraulic pump (6) in the first switching position takes place with a first pressure stage and wherein the pressure on the hydraulic cylinder unit (10) by the hydraulic pump (6) in the second switching position takes place with a second pressure stage, wherein the second pressure stage is lower than the first pressure stage. [2] Hydraulic system (1) according to claim 1, characterized byin that the valve arrangement (8) has a first pressure relief valve (17) and a first directional control valve (18), wherein the first directional control valve (18) blocks a flow path to the first pressure relief valve (17) in the first switching position of the valve arrangement (8), and wherein the first directional control valve (18) opens the flow path to the first pressure relief valve (17) in the second switching position of the valve arrangement (8), wherein the first pressure relief valve (17) is designed to set the second pressure stage. [3] Hydraulic system (1) according to claim 2, characterized byin that the valve arrangement (8) has a second directional control valve (19) and a second pressure relief valve (20), wherein the valve arrangement (8) can be switched into a third switching position, wherein the pressurization of the hydraulic cylinder unit (10) by the hydraulic pump (6) in the third switching position takes place with a third pressure stage in that the second directional control valve (19) in the third switching position blocks the flow path to the first pressure relief valve (17) and opens it to the second pressure relief valve (20), wherein the second pressure relief valve (20) is designed to set the third pressure stage. [4] Hydraulic system (1) according to one of the preceding claims, characterized by that the hydraulic accumulator (9) is designed to apply a fourth pressure stage to the hydraulic cylinder unit (10), wherein the fourth pressure stage is lower than the first pressure stage. [5] Hydraulic system (1) according to claim 4, characterized bythat the fourth pressure stage of the hydraulic accumulator (9) is lower than the second pressure stage, and wherein the third pressure stage is preferably lower than the fourth pressure stage. [6] Hydraulic system (1) according to one of the preceding claims, characterized by in that the hydraulic cylinder unit (10) is designed as a differential cylinder, and the hydraulic cylinder unit (10) has a hydraulic cylinder housing (12) with an interior space (13), wherein the piston (11) is movably arranged in the interior space (13) of the hydraulic cylinder housing (12), and the piston (11) separates the interior space (13) of the hydraulic cylinder housing (12) into a first working space (15) and a second working space (16), wherein the first working space (15) is connected to the hydraulic accumulator (9) and the second working space (16) is connected to the hydraulic pump (6). [7] Hydraulic system (1) according to one of the preceding claims, characterized byin that the valve arrangement (8) has a third directional control valve (21) between the hydraulic cylinder unit (10) and the hydraulic accumulator (9), wherein the third directional control valve (21) is switchable between a through position and a blocking position, wherein the third directional control valve (21) in the blocking position blocks the flow path from the hydraulic cylinder unit (10) to the hydraulic accumulator (9), but releases the flow path from the hydraulic accumulator (9) to the hydraulic cylinder unit (10). [8] Hydraulic system (1) according to one of the preceding claims, characterized by that the piston (11) is manually movable from the first closing position to a second closing position, wherein the first closing position lies between the opening position and the second closing position. [9] Hydraulic system (1) according to one of the preceding claims, characterized bythat when the piston (11) moves from the opening position to the first closing position, the valve arrangement (8) switches to the third switching position. [10] Hydraulic system (1) according to claim 8 or 9, characterized by that when the piston (11) moves from the first closing position to the second closing position, the valve arrangement (8) switches to the second switching position. [11] Hydraulic system (1) according to one of the preceding claims, characterized by that the first closing position of the piston (11) is adjustable. [12] Hydraulic system (1) according to claim 11 characterized by that the hydraulic section (5) has a detection unit and a control unit connected to the detection unit, so that the first closing position of the piston (11) can be set in the control unit and / or the movement of the piston (11) by the hydraulic accumulator (9) from the opening position to the first closing position can be switched off. [13] Hydraulic system (1) according to one of the preceding claims, characterized by in that the hydraulic section (5) is a first hydraulic section (5) and the hydraulic system (1) has at least one second hydraulic section (5) identical to the first hydraulic section (5), wherein the first hydraulic section (5) is connected to the second hydraulic section (5) in such a way that the piston (11) of the first hydraulic section (5) is movable independently of a piston (11) of the second hydraulic section (5), wherein the at least one second hydraulic section (5) is connected to the hydraulic pump (6). [14] Passenger restraint system (2) with at least one passenger restraint device (3) and a hydraulic system (1) according to one of the preceding claims.

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