Hydraulic circuit for providing resilient properties

Abstract

The invention relates to a hydraulic circuit (1) for generating a travel-dependent opposing force, the circuit having a hydraulic working chamber (2) which can be pressurized with hydraulic fluid in order to exert a force on a working piston (3), wherein: the working piston (3) has a second effective surface (4) at which the working piston (3) is acted on by a pressure acting in the hydraulic working chamber (2); a take-off element (5) is fastened to the working piston (3), by means of which take-off element the force generated by the hydraulic fluid in the working chamber (2) can be provided as a travel-dependent opposing force; the hydraulic working chamber (2) has at least one inflow opening (7) and at least one outflow opening (8); a working flow of hydraulic fluid can flow into the working chamber (2) via the inflow opening (7) and the working flow of hydraulic fluid can flow out of the working chamber (2) via the outflow opening; and, in accordance with a position of the working piston (3), a flow resistance of the outflow opening (8) and / or a flow resistance of the inflow opening (7) is controlled such that a pressure occurring in the hydraulic working chamber (2) is controlled travel-dependently in accordance with a position of the working position (3) such that the pressure increases with decreasing size of the working chamber (2).

Description

[0001] Hydraulic circuit to provide spring properties

[0002] The invention relates to a novel hydraulic circuit with which spring properties can be generated. In particular, the circuit makes it possible to dispense with very large mechanical springs for generating large forces and to replace such springs with the described hydraulic circuit.

[0003] Many hydraulic applications require very strong (and therefore large) springs to provide the required spring forces and spring travel. One such application is actuators for adjustable throttle valves. Such actuators typically require relatively large travel distances and, at the same time, very large actuating forces. The volume and weight of such springs are often considered a disadvantage.

[0004] The object of the present invention is to at least partially solve the problems described with reference to the prior art. In particular, a special, novel hydraulic circuit is proposed, the use of which eliminates the need for very large springs in many situations and applications.

[0005] This object is achieved by the invention according to the features of the independent patent claims. Further advantageous embodiments are specified in the dependent claims as well as in the description and, in particular, in the description of the figures. It should be noted that the person skilled in the art can combine the individual features in a technologically expedient manner and thus arrive at further embodiments of the invention.

[0006] What is to be described here is a hydraulic circuit for generating a path-dependent counterforce, comprising a hydraulic working chamber which can be pressurised with hydraulic fluid in order to exert a force on a working piston, wherein the working piston has a second active surface on which a pressure acting in the hydraulic working chamber acts on the working piston, and wherein a removal element is attached to the working piston, with which the force generated by the hydraulic fluid in the working chamber can be provided as a path-dependent counterforce, wherein the hydraulic working chamber has at least one inflow opening and at least one outflow opening, and wherein a working flow of hydraulic fluid can flow into the working chamber via the inflow opening and the working flow of hydraulic fluid can flow out of the working chamber via the outflow opening,wherein, depending on a position of the working piston, a flow resistance of the outflow opening and / or a flow resistance of the inflow opening is controlled in such a way that a pressure occurring in the hydraulic working chamber is controlled in a path-dependent manner depending on a position of the working piston in such a way that the pressure increases when the working chamber is reduced.

[0007] The purpose of the hydraulic circuit described is to generate a displacement-dependent counterforce that can be used for various applications. Possible applications include hydraulic actuators, which often use springs that can be replaced with the hydraulic circuit described here.

[0008] A path-dependent counterforce is generated, for example, by a classic mechanical spring (e.g. a torsion spring), whereby a spring has a spring characteristic curve that describes a relationship between the distance by which the spring is compressed or stretched / pulled apart and the spring force generated by the spring. For conventional springs (e.g. the torsion spring mentioned above), this relationship is linear. This means that, starting from a relaxed form of the spring, the spring force continues to increase linearly when the spring is compressed or stretched / pulled apart. With the hydraulic circuit described here, it is particularly possible to simulate or replace a spring with such a linear spring characteristic curve. The hydraulic circuit described here is particularly suitable for replacing springs that are compressed during use.The properties of a spring that is designed to be subjected to both tensile and compressive loads cannot be replicated with the hydraulic circuit described here. This would require arrangements in which several of the circuits described here interact and / or in which other (e.g., mechanical) means are provided by which a tensile movement can be converted into a compressive movement. Such means could be, for example, levers, deflectors, or other means.

[0009] The take-off element is, for example, a mechanical element connected to the working piston via a rod, from which the spring-like force generated by the hydraulic circuit can be tapped or made available for an intended application.

[0010] The hydraulic fluid used to operate the circuit described here is preferably essentially incompressible. The hydraulic device described is driven by a working flow of hydraulic fluid. The working flow of hydraulic fluid enters the working chamber through the inlet opening and exits the working chamber again via an outlet opening. By displacing the working piston or changing the position of the working piston, the volume of the working chamber can change. This can temporarily result in different volume flows at the inlet opening and the outlet opening. When the working piston is in a certain position, the working flow of hydraulic fluid through the inlet opening and the outlet opening is the same.

[0011] The working flow of hydraulic fluid required to operate the described hydraulic circuit is preferably provided by a hydraulic fluid source to which the inlet opening is connected. The working flow exiting the outlet opening is preferably discharged via a tank connection into a reservoir for "used" hydraulic fluid. Hydraulic fluid is preferably pumped out of such a reservoir using a hydraulic pump and pressurized in order to be made available to the hydraulic circuit described here (and possibly also to other hydraulic circuits in a larger system). Such a hydraulic pump can, for example, form the hydraulic fluid source. In further design variants, the working flow can also be fed to a throttled hydraulic fluid flow. The described hydraulic circuit acts like a hydraulic throttle for the working flow itself.

[0012] The hydraulic working chamber is preferably provided in a housing, which is in particular cylindrical. The working piston is movably mounted in the housing. The housing preferably provides a cylindrical chamber in which the working piston is movably mounted. The working chamber is therefore preferably formed by a part of this cylindrical chamber, which is delimited by the working piston. The working chamber can be enlarged or reduced by a movement of the working piston. The working chamber is delimited in particular by the housing and the working piston. The second active surface on the working piston preferably forms a wall / delimitation of the working chamber. The further walls / delimitations of the working piston are preferably formed by the housing.The term "second active surface" uses the prefix "two" here because, in preferred embodiments of the hydraulic circuit described, there is another first active surface on the working piston, which is arranged opposite the second active surface on the working piston. In these embodiments, explained in more detail below, the working flow preferably flows first past the first active surface and then past the second active surface. However, the first active surface does not have to be present in all embodiments of the hydraulic circuit described here. The prefix "two" therefore does not indicate that a first active surface must also be present. The second active surface can functionally be referred to as an active surface on the working chamber or as an active surface subjected to hydraulic spring force.

[0013] The inflow opening and / or the outflow opening are designed such that their flow resistance for the hydraulic fluid flowing through them, or in particular their flow-through cross section, changes depending on the position of the working piston. Particularly preferably, the inflow opening or the outflow opening are arranged on a housing forming the working chamber or in / on a cylinder chamber such that the working piston is close to this opening (inflow opening or outflow opening) during operation of the hydraulic device. Particularly preferably, the working piston passes over this inflow opening or outflow opening when it changes its position or moves. Particularly preferably, a different interaction of this inflow opening or outflow opening occurs depending on the position of the working piston.Preferably, this interaction achieves or at least supports the influence of the working flow of hydraulic fluid through the inlet opening, the outlet opening and the working chamber.

[0014] The described hydraulic circuit is configured so that the working flow of hydraulic fluid increases or becomes larger when the volume of the working chamber is reduced and the force provided by the hydraulic circuit increases. Particularly when small forces are generated by the hydraulic circuit or tapped at the hydraulic circuit, the (required) working flow of hydraulic fluid is preferably small. These properties of the hydraulic circuit are advantageous because loss or throttling of the supplied, pressurized hydraulic fluid is minimal when the acting forces are small. Thus, the described hydraulic circuit can be used efficiently, particularly when the large forces provided by the hydraulic circuit are only required temporarily.

[0015] It is particularly preferred if a throttle control which is operatively coupled to the working piston is arranged at the inlet opening and is designed such that a working flow flowing into the working chamber increases when the working piston reduces the working chamber.

[0016] In other words: The throttle control opens further when the working piston is moved in such a way that the working space of the hydraulic circuit is reduced and the throttle control closes more when the working piston is moved in such a way that the working space of the hydraulic circuit is increased.

[0017] The throttle control is in particular designed such that it releases an enlarged inflow cross-section at the inflow opening when the working piston is moved such that the working chamber is reduced. In preferred embodiments of the circuit, this is achieved via a notch on the working piston and a specially designed inflow opening. The inflow opening is preferably arranged on a circumferential surface of a cylinder chamber in which the working piston is movably mounted and in which the working chamber is arranged. The inflow opening is preferably arranged in the region of the circumferential surface in which the working piston is located. The working piston preferably sweeps over the inflow opening when it changes its position. Particularly preferably, the throttle control is formed by structures formed on the working piston.Particularly preferably, the effective coupling between the working piston and the throttle control is achieved in that the working piston passes over the inlet opening when it changes its position.

[0018] It is also preferred if the throttle control is designed with a notch which releases a variable inflow cross-section into the working chamber depending on a position of the working piston.

[0019] The notch is particularly preferably formed on the working piston. The notch is particularly preferably brought into overlap with the inflow opening to a different extent or at a different location depending on the position of the working piston. In preferred embodiments, the notch is aligned along or parallel to a direction of movement of the working piston and is elongated. The notch particularly preferably has a different depth along a direction of movement of the working piston. Depending on the position of the working piston, the inflow opening is particularly preferably brought into overlap with a section of the notch which has a different depth. Further preferably, the depth of the notch at the location at which the notch is brought into overlap with the inflow opening also defines an inflow cross-section into the working chamber.

[0020] Furthermore, it is preferred if the outflow opening is provided with a throttle element with a predetermined pressure-volume flow characteristic curve, which is designed such that the volume flow through the outflow opening increases with an increase in pressure.

[0021] A throttle element with a specified pressure-volume flow characteristic determines the pressure loss of the hydraulic fluid when it flows out of the working chamber. The greater the volume flow of hydraulic fluid that flows into the working chamber through the inlet opening and the throttle control, the more hydraulic fluid must also flow out of the working chamber through the outlet opening and the throttle element.

[0022] Due to the predetermined pressure-flow characteristic of the throttle element, a higher pressure is then established in the working chamber. This results in a greater force that must be applied to hold the working piston in a specific position. This is the spring force or spring-like force generated by the hydraulic circuit described.

[0023] In this context, the throttle control is particularly preferably designed such that, for a specific opening width or a specific position of the working piston, it has a pressure-volume flow characteristic curve which specifies a disproportionately increasing pressure loss with an increasing volume flow. This preferably applies to every position of the working piston, wherein the pressure-volume flow characteristic curve is preferably compressed and / or shifted by a displacement of the working piston and a change in the volume of the working chamber. Preferably, a reduction in the size of the working chamber and the corresponding change in the position of the working piston lead to a lowering / compression of the pressure-volume flow characteristic curve of the throttle control. Preferably, an enlargement of the working chamber and the corresponding change in the position of the working piston lead to an increase / stretching of the pressure-volume flow characteristic curve of the throttle control.

[0024] The interaction of the pressure-volume flow characteristic curve of the throttle element and the pressure-volume flow characteristic curve of the throttle control as well as the dependence of the pressure-volume flow characteristic curve of the throttle control on the volume of the working chamber and the position of the working piston preferably produce the dependence of the pressure in the working chamber on the volume of the working chamber and the position of the working piston and thus the spring force or spring-like force caused by the described hydraulic circuit on a take-off element of the described hydraulic circuit.

[0025] It is also preferred if the throttle element at the outlet opening is a spring-loaded check valve.

[0026] The spring characteristic of a check valve spring preferably determines the pressure-volume flow characteristic of the throttle element. In particular, the hydraulic circuit described here amplifies the spring characteristic of the check valve spring of the throttle element such that the travel-dependent characteristic of the spring force or spring-like force on the discharge element generated by the described circuit is proportional to the spring characteristic of the check valve spring.

[0027] In preferred embodiments, the hydraulic circuit has a hydraulic control chamber which can be pressurized with hydraulic fluid and which is arranged opposite the working chamber on the working piston, wherein the working piston has a first active surface on which a pressure acting in the hydraulic control chamber acts on the working piston in opposition to a pressure acting in the working chamber, wherein the control chamber is connectable to a control pressure source and wherein the inflow opening of the working chamber is connected to the control chamber such that hydraulic fluid flowing out of the control chamber flows into the working chamber. Particularly preferably, the control chamber is formed in a housing in which the working chamber of the described circuit is also arranged.Preferably, a housing provides a cylinder chamber in which the working piston is movably mounted, wherein the working piston separates the working chamber and the control chamber from one another in the cylinder chamber. Preferably, a pressure present in the control chamber acts on the working piston in a manner opposite to a pressure in the working chamber. Hydraulically, the control chamber and the working chamber are preferably connected in series. A control pressure source for providing hydraulic fluid to pressurize the control chamber is thereby preferably also used as a hydraulic fluid source for operating the hydraulic circuit formed with the aid of the working chamber for simulating spring properties.

[0028] The throttle control is preferably located between the control chamber and the working chamber. The inflow cross-section of the throttle control provides a transition resistance for hydraulic fluid as it flows from the control chamber into the working chamber. The inflow cross-section preferably increases when the pressure in the control chamber increases. This preferably occurs through a displacement of the working piston, which releases a larger inflow cross-section.

[0029] When the control chamber is subjected to greater pressure from the control pressure source, the working piston moves. As a result of the reduced flow resistance of the throttle control and the throttle element located at the outlet opening of the working chamber, the pressure in the working chamber also increases, creating a force equilibrium that causes a specific position of the working piston and thus also of a take-off element attached to the working piston.

[0030] The design described here offers a unique opportunity to create a compact actuator with a hydraulic spring, capable of generating very high actuating forces within a compact volume. This design behaves as if it contained a very large / strong mechanical spring.

[0031] It is preferred if a second effective surface, at which a pressure acting in the working chamber acts on the working piston, is larger than a first effective surface, at which a pressure acting in the control chamber acts on the working piston.

[0032] It is also preferred if a differential area, by which the first effective area is smaller than the second effective area, on the side of the first effective area of ​​the working piston is connected to the outflow opening of the working chamber.

[0033] Due to a design in which the working chamber is arranged downstream of the control chamber in the direction of hydraulic fluid flow, the pressures in the working chamber are always lower than those in the control chamber (in any stationary operating situation). To ensure the necessary force equilibria on the working piston for the desired operation of the hydraulic circuit, the second effective area is preferably larger than the first effective area. The effective areas (first effective area, second effective area, and / or the differential area) can also be further reduced or increased by the take-off element or a rod that connects the take-off element to the working piston and leads it out of the housing (or out of a cylinder chamber provided in a housing in which the working piston is accommodated).

[0034] Furthermore, the hydraulic circuit preferably has a tank pressure chamber into which the differential surface adjoins, wherein the at least one outflow opening of the working chamber is connected to the tank pressure chamber, so that hydraulic fluid flowing out of the working chamber flows into the tank pressure chamber, wherein the tank pressure chamber further has a tank connection through which hydraulic fluid can be discharged from the tank pressure chamber. The tank pressure chamber is preferably also arranged within the housing or within a cylinder chamber provided with the housing. Preferably, the tank pressure chamber is separated from the control chamber by an extension formed on the working piston. Preferably, the cylinder chamber or the housing has a tapered section into which the extension on the working piston extends. Particularly preferably, the tank pressure chamber is formed in this tapered section of the cylinder chamber or the housing.The pressure applied to the differential surface in the tank pressure chamber is preferably significantly lower than the pressure in the working chamber during operation of the hydraulic circuit.

[0035] In preferred embodiments, the outflow opening and the throttle element are arranged hydraulically between the working chamber and the tank pressure chamber, so that hydraulic fluid escaping from the working chamber and the outflow opening enters the tank pressure chamber.

[0036] Furthermore, it is preferred if the outflow opening is designed with a connecting line in the working piston.

[0037] This enables a particularly compact design of the hydraulic circuit. In other design variants, it is also possible for the throttle element to be located outside the working piston, for example, in a housing that also provides the cylinder chamber in which the working piston is located.

[0038] The invention and the technical context of the invention are explained in more detail below with reference to the figures. The figures show preferred embodiments to which the invention is not limited. It should be noted in particular that the figures, and in particular the proportions depicted in the figures, are only schematic. They show:

[0039] Fig. 1: a mechanical device for generating a path-dependent counterforce; Fig. 2: a mechanical device for generating a manipulated variable depending on a control pressure;

[0040] Fig. 3: a variant of a hydraulic circuit for generating a path-dependent counterforce;

[0041] Fig. 4: a further embodiment of a hydraulic circuit for generating a path-dependent counterforce;

[0042] Fig. 5: a hydraulic circuit for generating a control variable in response to a control pressure; and

[0043] Fig.6: another variant of a hydraulic circuit for

[0044] Generation of a control variable depending on a control pressure.

[0045] Fig. 1 shows a mechanical device in which a spring 14 is used to generate a path-dependent counterforce. The spring force of the spring 14 is provided at a removal element 5. The spring 14 is clamped between a plunger 22 and a housing 23. The removal element 5 is mechanically connected to the plunger 22 and thus to the spring 14 via a rod 6 in such a way that the spring force of the spring 14 acts on the removal element 5. Depending on the force F acting on the removal element 5, the spring 14 is compressed to varying degrees. A spring characteristic curve of the spring 14 provides a relationship between the position of the removal element 5 and the force acting on the removal element 5, which relationship is linear for conventional springs 14.

[0046] Fig. 2 shows a mechanical device for generating a manipulated variable as a function of a control pressure provided by a control pressure source 19. The device according to Fig. 2 is based on the device according to Fig. 1. Here, too, a spring 14 is braced between a housing 23 and a plunger 22. In addition, a control chamber 17 is provided, which can be pressurized with a pressure from a control pressure source 19. The pressure in the control chamber 17 acts on a first active surface 18 on the plunger 22, opposite the spring 14. The pressure in the control chamber 17 thus acts against the spring force of the spring 14. The position of the removal element 5 in the load-free state can be adjusted with a force F = 0 Newton on the removal element 5 via the pressure in the control chamber 17 and the spring characteristic curve of the spring 14.When loaded with a force F <> 0 Newton on the pickup element 5, the volume of hydraulic fluid in the control chamber 17 determines the position of the pickup element 5. Depending on the magnitude of the force F acting on the pickup element 5, corresponding pressures are required in the control chamber 17 to maintain a specific position of the pickup element 5. Depending on the position of the pickup element 5, the spring 14 is compressed to different extents. The spring force of the spring 14 is greater the more the spring 14 is compressed. The pressure required in the control chamber 17 to maintain a specific position of the pickup element 5 therefore also depends on the spring force of the spring 14. The spring force of the spring 14 is superimposed on the force F acting on the pickup element 5.

[0047] Figs. 3 and 4 show the principle described here, with which the properties of a spring 14 can be hydraulically simulated in the device according to Fig. 1. Very large forces can be generated with the hydraulic circuits 1 according to Figs. 3 and 4, which would require very large springs 14 to generate with the purely mechanical structure according to Fig. 1. The hydraulic circuits 1 according to Figs. 3 and 4 require a permanent supply of pressurized hydraulic fluid from a hydraulic fluid source 24, which is discharged into a reservoir (referred to here as tank connection 16). However, this is perfectly acceptable for various applications.

[0048] The hydraulic circuit 1 according to Figs. 3 and 4 each has a working piston 3, which is guided in a housing 23 and defines a working chamber 2 within the housing 23. The working chamber 2 is filled with hydraulic fluid during operation of the hydraulic circuit 1. The working piston 3 forms a second active surface 4, against which hydraulic fluid located in the working chamber 2 presses. The effect of the pressure of the hydraulic fluid in the working chamber 2 on the active surface 4 corresponds to the spring force of the spring 14 according to the mechanical device shown in Fig. 1.

[0049] The hydraulic circuit 1 according to Figs. 3 and 4 is designed such that the pressure of the hydraulic fluid in the working chamber 2 increases as the working piston 3 is moved further downward. This corresponds to the properties that would also be provided by a spring 14 arranged in the working chamber 2 or on the side of the working chamber 2 on the working piston 3 at the second active surface 4. The more such a spring 14 is compressed, the stronger the resulting spring force would be. The hydraulic circuit 1 is accordingly designed such that as the working chamber 2 is reduced in size, the pressure in the working chamber 2 increases.

[0050] This behavior is achieved by a permanent flow of hydraulic fluid from the hydraulic fluid source 24 flowing into the working chamber 2 via an inlet opening 7 and flowing out of the working chamber 2 again via an outlet opening 8. A throttle control 9 is provided at the inlet opening 7 and is coupled to the working piston 2 in such a way that the inlet cross-section 11 of the inlet opening 7 is enlarged when the working piston 3 moves in such a way that the working chamber 2 is reduced in size. Thus, the amount of hydraulic fluid flowing into the working chamber 2 increases as a result of a reduction in the size of the working chamber 2.

[0051] Fig. 3 shows how such a throttle control 9 can be implemented in concrete terms. The inlet opening 7 is arranged such that it is at least partially covered by the working piston 3. A notch 10 is arranged in the working piston 3, which is connected to the working chamber 2 via a connecting channel 25 and which, depending on the position of the working piston 3, releases a differently sized inlet cross section 11 into the working chamber 2. The further down the working piston 3 is located or the smaller the working chamber 2 is, the larger the released inlet cross section 11 and the more hydraulic fluid can flow through the inlet opening 7 into the working chamber 2.

[0052] This principle is illustrated more generally in Fig. 4. Here, an active coupling 26 between the working piston 3 and the throttle control 9 is shown with a dashed line. This active coupling 26 is designed such that a downward movement of the working piston 3 or a reduction in the size of the working chamber 2 causes an increase in the inflow cross-section 11.

[0053] A throttle element 12 is provided at the outflow opening 8, which in both embodiments according to Figs. 3 and 4 is designed as a spring-loaded check valve 13. The greater the pressure in the working chamber 2 or at the outflow opening 8, the wider the throttle element 12 is opened and the more hydraulic fluid flows from the working chamber 2 via the outflow opening 8 into a tank connection 16. In this way, the throttle element 12 at the outflow opening 8 controls the pressure in the working chamber 2 and ensures that the pressure in the working chamber 2 increases when the volume flow of hydraulic fluid through the working chamber 2 is increased. A volume flow of hydraulic fluid is therefore specified via the throttle control 9 and the throttle element 12 depending on the position of the working piston 3, as a result of which a pressure is established in the working chamber 2 due to the effect of the throttle element 12.

[0054] According to Fig. 4, it is also shown that the inlet opening 7 and the outlet opening 8 can also open into the working chamber 2 together. It is important that the interaction of the throttle control 9 at the inlet opening 7 and the throttle element 12 at the outlet opening 8 determines the dependence of the pressure of the hydraulic fluid in the working chamber 2 on the position of the working piston 3. It is also possible for this pressure to be transmitted to the working chamber 2 via a common inlet channel 27 from the inlet opening 7 and the outlet opening 8 to the working chamber 2. Figs. 5 and 6 now show hydraulic circuits 1 for generating a manipulated variable as a function of a control pressure, which control pressure source 19 provides. The hydraulic circuits 1 according to Figs. 5 and 6 are based on the hydraulic circuits 1 according to Figs. 3 and 4.

[0055] In terms of their operation, the hydraulic circuits 1 according to the device Figs. 5 and 6 provide a functionality corresponding to the mechanical / hydraulic device according to Fig. 2.

[0056] The hydraulic circuits 1 according to Figs. 5 and 6 can generate very large control forces, which would require very large springs 14 with the mechanical / hydraulic setup shown in Fig. 2. The hydraulic circuits 1 according to Figs. 5 and 6 require a permanent inflow of pressurized hydraulic fluid from a hydraulic fluid source 24, which is discharged into a reservoir (referred to here as tank connection 16). In this respect, the hydraulic circuits 1 according to Figs. 5 and 6 are designed correspondingly to the hydraulic circuits 1 according to Figs. 3 and 4 or are conceptually based on these circuits.

[0057] The need for a permanent supply of pressurized hydraulic fluid is absolutely acceptable, especially in these hydraulic circuits 1 according to Figs. 5 and 6. This is especially true because it is possible to combine a control pressure source 19 for providing the control pressure and a hydraulic fluid source 24 for providing a permanent flow of hydraulic fluid for operating the hydraulic circuit 1 and for providing the resilient behavior of the hydraulic circuit 1.

[0058] The hydraulic circuits 1 according to Figs. 5 and 6 each have a control chamber 17, which corresponds to the control chamber 17 of the device according to Fig. 2. The control chamber 17 is located within the housing 23, in which the working piston 3 is arranged such that the control chamber 17 is delimited by a first active surface 18 formed on the working piston 3, and that a pressure of a hydraulic fluid present in the control chamber 17 acts on the working piston 3 at the first active surface 18. This corresponds to the situation according to Fig. 2.

[0059] The working piston 3 has, on the other side, a second active surface 4, which delimits a working chamber 2. This working chamber 2 is also arranged within the housing 23. In other words, the working piston 3 divides the space available in the housing 23 for hydraulic fluid into the working chamber 2 and the control chamber 17. By displacing the working piston 3, the control chamber 17 is enlarged and the working chamber 2 is reduced, or vice versa. A removal element 5 is attached to the working piston 3 via a rod 6, with which the described hydraulic circuit 1 can be used for control tasks, corresponding to the device according to Fig. 2.

[0060] The control pressure source 19 and the hydraulic fluid source 24 have been combined in the hydraulic circuits 1 according to Figs. 5 and 6. When using the hydraulic circuits 1 according to Figs. 5 and 6, a permanent outflow of hydraulic fluid from the hydraulic fluid source 24 or from the control pressure source 19 into a tank connection 16 occurs, which does not occur in the device according to Fig. 2. However, such a permanent outflow of hydraulic fluid is acceptable or possibly even desirable for many applications because the pressure of a hydraulic fluid flow must be throttled anyway and this hydraulic fluid flow can be used to operate the hydraulic circuit 1 according to Figs. 5 and 6.

[0061] 5 and 6, the control chamber 17 is arranged upstream of the working chamber 2 in the direction of flow of the hydraulic fluid from the hydraulic fluid source 24 or the control pressure source 19 to the tank connection 16. The inlet opening 7 into the working chamber 2 is formed between the control chamber 17 and the working chamber 2. The throttle control 9 at the inlet opening 7 is designed, in particular, with a notch 10 on the working piston 3 such that an inlet cross-section 11 or the quantity of hydraulic fluid that passes from the control chamber 17 into the working chamber 2 increases the further the working piston 3 has been moved in the direction towards the working chamber 2 or the smaller the working chamber 2 is. The outlet opening 8, as in the hydraulic circuits 1 according to FIGS. 3 and 4, is provided with a throttle element 12, which is designed as a spring-loaded check valve 13.

[0062] 5 and 6, the second effective area 4 of the working piston 3, which is directed towards the working chamber 2, is larger than the first effective area 18 of the working piston 3, which is directed towards the control chamber 17. Due to the throttle control 9, a pressure loss of the hydraulic fluid occurs when it flows through the inlet opening 7 or when it passes from the control chamber 17 into the working chamber 2. Due to this fact, it is necessary for the second effective area 4 to be larger than the first effective area 18, because otherwise the pressure acting on the first effective area 18 would generate greater forces than the pressure acting on the second effective area 4, and the resilient properties of the hydraulic circuit 1 would be impaired. For this reason, the hydraulic circuit 1 also has a tank pressure chamber 21, which is delimited by a differential area 20 formed on the working piston 3.The differential area 20 corresponds to the area difference between the first effective area 18 and the second effective area 4. In the tank pressure chamber 21, the pressure of the tank connection 16 is present, which is significantly lower than the pressure in the working chamber 2. For this reason, the pressure applied to the differential area 20 does not affect the ratio of the forces on the working piston 3 necessary for the resilient properties of the hydraulic circuit 1, or not in a disturbing manner.

[0063] In the embodiment shown in Fig. 5, the throttle element 12 is integrated into the working piston 3. For this purpose, a connecting line 15 is formed in the working piston 3, which connects the working chamber 2 and the tank pressure chamber 21 and in which the throttle element 12 is formed. The outflow opening 8 is formed by the connecting line 15. In the embodiment shown in Fig. 6, the throttle element 12 is arranged outside the working piston 3 (e.g., within the housing 23).

[0064] List of reference symbols

[0065] Hydraulic circuit Working chamber Working piston Second effective area Removal element Rod Inlet opening Outlet opening Throttle control Notch

[0066] Inlet cross-section throttle element spring-loaded check valve mechanical spring connecting line tank connection control chamber first effective area control pressure source differential area tank pressure chamber

[0067] Piston housing hydraulic fluid source connecting channel active coupling inlet line

Claims

Patent claims 1. A hydraulic circuit (1) for generating a path-dependent counterforce, comprising a hydraulic working chamber (2) which can be pressurized with hydraulic fluid in order to exert a force on a working piston (3), wherein the working piston (3) has a second active surface (4) on which a pressure acting in the hydraulic working chamber (2) acts on the working piston (3), and wherein a take-off element (5) is attached to the working piston (3), with which the force generated by the hydraulic fluid in the working chamber (2) can be provided as a path-dependent counterforce, wherein the hydraulic working chamber (2) has at least one inflow opening (7) and at least one outflow opening (8), and wherein a working flow of hydraulic fluid can flow into the working chamber (2) via the inflow opening (7) and the working flow of hydraulic fluid can flow out of the working chamber (2) via the outflow opening,wherein, depending on a position of the working piston (3), a flow resistance of the outflow opening (8) and / or a flow resistance of the inflow opening (7) is controlled such that a pressure occurring in the hydraulic working chamber (2) is controlled in a path-dependent manner depending on a position of the working piston (3) such that the pressure increases when the working chamber (2) is reduced in size.

2. Hydraulic circuit (1) according to claim 1, wherein a throttle control (9) which is operatively coupled to the working piston (3) is arranged at the inflow opening (7), which throttle control is designed such that a working flow flowing into the working chamber (2) increases when the working piston (3) reduces the size of the working chamber (2).

3. Hydraulic circuit (1) according to claim 1 or 2, wherein the throttle control (9) is designed with a notch (10) which releases a variable inflow cross-section (11) into the working chamber (2) depending on a position of the working piston (3).

4. Hydraulic circuit (1) according to one of the preceding claims, wherein the outflow opening (8) is provided with a throttle element (12) with a predetermined pressure-volume flow characteristic curve, which is arranged such that with an increase in pressure the volume flow through the outflow opening (8) increases.

5. Hydraulic circuit (1) according to claim 4, wherein the throttle element (12) at the outflow opening (8) is a spring-loaded check valve (13).

6. Hydraulic circuit (1) according to one of the preceding claims, comprising a hydraulic control chamber (17) which can be pressurized with hydraulic fluid and which is arranged on the working piston (3) opposite the working chamber (2), wherein the working piston (3) has a first active surface (18) on which a pressure acting in the hydraulic control chamber (17) acts on the working piston (3) in the opposite direction to a pressure acting in the working chamber (2), wherein the control chamber (17) can be connected to a control pressure source (19) and wherein the inflow opening (7) of the working chamber (2) is connected to the control chamber (17), so that hydraulic fluid flowing out of the control chamber (17) flows into the working chamber (2).

7. Hydraulic circuit (1) according to claim 6, wherein a second effective surface (4), at which a pressure acting in the working chamber (2) acts on the working piston (3), is larger than a first effective surface (18), at which a pressure acting in the control chamber (17) acts on the working piston (3).

8. Hydraulic circuit (1) according to claim 7, wherein a differential area (20) by which the first effective area (18) is smaller than the second effective area (4) on the side of the first effective area (18) of the working piston (3) is connected to the outflow opening (8) of the working chamber (2).

9. Hydraulic circuit (1) according to claim 8, comprising a tank pressure chamber (21) which adjoins the differential surface (20), wherein the at least one outflow opening (8) of the working chamber (2) is connected to the tank pressure chamber (21) so that hydraulic fluid flowing out of the working chamber (2) flows into the tank pressure chamber (21), wherein the tank pressure chamber (21) further comprises a tank connection (16) at which hydraulic fluid can be discharged from the tank pressure chamber (21).

10. Hydraulic circuit (1) according to one of claims 6 to 9, wherein the outflow opening (8) is designed with a connecting line (15) in the working piston (3).

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