HYDRAULIC LOCKING DEVICE FOR AN EXOSKELETON JOINT AND EXOSKELETON JOINT

Abstract

A hydraulic locking device for an exoskeleton joint with an extendable and retractable hydraulic cylinder, a tank and a switching valve. The hydraulic cylinder is connected to the tank via a line arrangement and the switching valve is disposed in the line arrangement. The switching valve is switchable between a release position and a blocking position. The hydraulic cylinder is freely movable in the release position of the switching valve, and the switching valve prevents retraction of the hydraulic cylinder in the blocking position. The hydraulic locking device further comprises a housing, and the hydraulic cylinder is a plunger cylinder with a plunger cylinder housing and a plunger piston movably arranged in the plunger cylinder housing, the plunger cylinder being arranged within the housing. Further, an exoskeleton joint having such a hydraulic locking device is disclosed.

Claims

1. A hydraulic locking device for an exoskeleton joint, comprising: a housing; an extendable and retractable hydraulic cylinder; a tank; and a switching valve, wherein the hydraulic cylinder is connected to the tank via a line arrangement and the switching valve is disposed in the line arrangement, wherein the switching valve is configured to be switched between a release position and a blocking position, wherein the hydraulic cylinder is freely movable in the release position of the switching valve and the switching valve prevents retraction of the hydraulic cylinder in the blocking position, wherein the hydraulic cylinder is a plunger cylinder with a plunger cylinder housing and a plunger piston movably disposed in the plunger cylinder housing, wherein the plunger cylinder is disposed within the housing.

2. The hydraulic locking device according to claim 1, wherein the hydraulic locking device has a rotary shaft and a lever, wherein the rotary shaft is rotatably mounted about a first axis of rotation on the housing and the plunger cylinder housing is rotatably mounted about a second axis of rotation on the housing, and the lever comprises a shaft coupling portion and a piston coupling portion, the shaft coupling portion being non-rotatably connected to said rotary shaft, and wherein the piston coupling portion is rotatably connected to the plunger.

3. The hydraulic locking device according to claim 2, wherein the rotary shaft is rotatable between a first end position and a second end position, wherein a dead point position is located between the first end position and the second end position, wherein the plunger is extended in the first end position and enters the dead point position upon rotation of the rotary shaft and extends upon rotation of the rotary shaft from the dead point position to the second end position.

4. The hydraulic locking device according to claim 1, wherein the switching valve has a check valve which is active in the blocking position, the check valve opening in the direction of flow from the tank to the plunger cylinder.

5. The hydraulic locking device according to claim 1, wherein the plunger cylinder has a check valve, the check valve opening in the direction of flow from the tank to the plunger cylinder.

6. The hydraulic locking device according to claim 5, the plunger comprises the check valve.

7. The hydraulic locking device according to claim 1, the plunger piston and the plunger cylinder housing define a plunger chamber, the plunger chamber being connected to the tank via a pressure relief valve.

8. The hydraulic locking device according to claim 1, wherein the housing forms said tank, wherein the plunger cylinder s disposed within the tank.

9. An exoskeleton joint comprising a hydraulic locking device according to claim 1.

10. The exoskeleton joint according to claim 9, wherein the exoskeleton joint has a first receptacle disposed on the housing and a second receptacle movably mounted on the housing via a four-bar linkage.

Description

THE BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a hydraulic circuit diagram of a hydraulic locking device known from the prior art;

[0029] FIG. 2 is a hydraulic circuit diagram of a hydraulic locking device according to the invention in accordance with a first embodiment;

[0030] FIG. 3 is a hydraulic circuit diagram of a hydraulic locking device according to the invention in accordance with a second embodiment;

[0031] FIG. 4 is a hydraulic circuit diagram of a hydraulic locking device according to the invention in accordance with a third embodiment;

[0032] FIG. 5 is a first perspective view of a hydraulic locking device according to the invention;

[0033] FIG. 6 is the hydraulic locking device according to FIG. 5 in a second perspective view;

[0034] FIG. 7 is a partially exposed side view of the hydraulic locking device according to FIG. 5;

[0035] FIG. 8 is another partially exposed side view of the hydraulic locking device according to FIG. 5,

[0036] FIG. 9 is the view according to FIGS. 7 and 8, with the plunger cylinder shown in various positions,

[0037] FIG. 10 is a side view of an exoskeleton joint with a hydraulic locking device according to FIG. 2, and

[0038] FIG. 11 is a partial section through the exoskeleton joint shown in FIG. 10.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] FIG. 2 shows a hydraulic circuit diagram of a hydraulic locking device 10 according to the invention for an exoskeleton joint 50 according to a first embodiment. The hydraulic locking device 10 can be used, for example, with an exoskeleton knee joint 50, as exemplified in FIGS. 10 and 11. The hydraulic locking device 10 comprises a hydraulic cylinder configured as a plunger cylinder 12, which is connected to a tank 16 via a line arrangement 14. Further, the hydraulic locking device 10 comprises a housing 18 forming the tank 16. The plunger cylinder 12 is disposed within the housing 18 and thus within the tank 16. Thus, the plunger cylinder 12 is under hydraulic fluid.

[0040] A switching valve 20 is disposed in the line arrangement 14, which can be switched between a release position FS and a blocking position SS. The switching valve 20 comprises a biasing element 23 which biases the switching valve into the release position FS. An actuating device 27 is actuated to switch the switching valve 20 to the blocking position SS. In this embodiment, the actuating device 27 is an electromagnet that is energized via a (not shown) higher-level control system.

[0041] The plunger cylinder 12 comprises a plunger cylinder housing 22 and a plunger piston 24 axially movable within the plunger cylinder housing 22. The plunger piston 24 and the plunger cylinder housing 22 define a variable volume plunger chamber 26.

[0042] If free movement is required, the switching valve 20 is in the release position FS and hydraulic fluid can be sucked from the tank 16 via the line arrangement 14 when the plunger piston 24 is extended. Accordingly, hydraulic fluid is displaced from plunger chamber 26 by an inward movement of plunger piston 24 and is directed into tank 16 via the line arrangement. As soon as the switching valve 20 is switched to the blocking position SS, the connection between the tank 16 and the plunger chamber 26 is blocked. The plunger piston 24 is then fixed in the position relative to the plunger cylinder housing 22, and cannot extend or retract.

[0043] As noted above, the plunger cylinder 12 is disposed entirely within the tank 16 so that any potential leakage from the plunger cylinder 12 is not problematic. Thus, the plunger cylinder 12 can be of simple construction without the need for a high pressure seal between the plunger piston 24 and the plunger cylinder housing 22. A gap seal is sufficient between the plunger piston 24 and the plunger cylinder housing 22. This is because possible leakage-induced movement of the plunger piston 24 despite the switching valve 20 being switched to the blocking position SS is tolerable when the hydraulic locking device 10 is used in an exoskeleton joint 50. The blocking of the movement of the plunger piston 24 serves to support a load, for example during a stance phase. However, this phase is very limited in time, so that some leakage, and thus some movement of the plunger piston 24, over this short period of time is insignificant.

[0044] FIG. 3 shows a hydraulic circuit diagram of a second embodiment of a hydraulic locking device 10 according to the invention. The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in that a check valve 28 is disposed in the plunger piston 24. The check valve 28 is a spring-loaded check valve 28 and it opens against the spring force in the direction of flow from the tank 16 to the plunger chamber 26.

[0045] In the blocking position SS of the switching valve 20, the plunger piston 24 is locked against retraction. However, the plunger piston 24 can continue to extend in the blocking position SS of the switching valve 20, since hydraulic fluid can be sucked into the plunger chamber 26 via the check valve 28. Using the example of the exoskeleton knee joint 50 described in more detail below, this means that the knee can be extended even further when the switching valve 20 is in the blocking position SS. However, bending of the knee is not possible because the plunger piston 24 is locked against retraction in the locking position SS of the switching valve 20.

[0046] The integration of the check valve 28 into the plunger piston 24 results in a particularly compact design of the plunger cylinder 12.

[0047] FIG. 4 shows a hydraulic circuit diagram of a third embodiment of a hydraulic locking device 10 according to the invention. The hydraulic locking device 10 according to the third embodiment differs from the hydraulic locking device 10 according to the second embodiment shown in FIG. 3, firstly, in that the check valve 28 is not disposed in the plunger piston 24, but in the switching valve 20. As shown, the check valve 28 is active in the blocking position SS of the switching valve 20 in the direction of flow from the tank 16 to the plunger chamber 26. The check valve 28 also permits further extension of the plunger piston 24 relative to the plunger cylinder housing 22 in the blocking position SS of the switching valve 20, by drawing hydraulic fluid into the plunger chamber 26 via the line arrangement 14 in that the check valve 28 is opened during an extending movement of the plunger piston 24 from the tank 16. Also in this embodiment, the check valve 28 is a spring-loaded check valve 28 and it opens against the spring force in the direction of flow from the tank 16 to the plunger chamber 26.

[0048] Secondly, the third embodiment of the hydraulic locking device 10 according to the invention shown in FIG. 4 differs from the embodiment shown in FIG. 3 in that a branch line 30 branches off from the line arrangement 14 between the switching valve 20 and the plunger chamber 26. As shown, the branch line 30 is disposed within the housing 18 such that the branch line 30 opens into the tank. A pressure relief valve 32 is disposed in the branch line, which is a safety valve and protects the high pressure side of the hydraulic locking device 10 against damage. A maximum permissible pressure is set at the pressure relief valve 32. As soon as the pressure in the plunger chamber 26, and thus also at least in portions of the line arrangement 14, exceeds the maximum permissible pressure set at the pressure relief valve 32, the pressure relief valve 32 opens and the plunger chamber 26 is relieved to the tank 16.

[0049] Of course, a branch line 30 with a pressure relief valve 32 can also be used in the embodiments of the hydraulic locking device 10 shown in FIGS. 2 and 3. Furthermore, it is also conceivable that the pressure relief valve 32 is provided in the plunger piston 24 as an alternative to or in addition to the check valve 28.

[0050] The specific structural design of the hydraulic locking device 10 is explained in more detail below with reference to FIG. 5 to FIG. 9 and FIG. 11. The hydraulic locking device 10 described here corresponds to the embodiment shown in FIG. 3, whereby the following explanations also apply accordingly to the embodiments shown in FIG. 2 and FIG. 4.

[0051] The housing 18 of the hydraulic locking device 10 includes a base body 36 and a cover 38. The base body 36 and the cover 38 form an enclosed space within the housing 18, which forms the tank 16. The switching valve 20 is secured to the exterior of the housing, and a portion of the line arrangement 14 also extends from the exterior of the housing 18 into the interior of the housing 18, see FIG. 5. Further, a first receptacle 52 is disposed adjacent the switching valve 20 on the exterior of the housing 18. The first receptacle 52 serves to fix the exoskeleton joint 50 to the exoskeleton, for example by connecting it to a thigh 54 of the exoskeleton, cf. also FIG. 10.

[0052] FIGS. 7 to 9 show a side view of the hydraulic locking device 10, with the cover 38 removed. As can be seen, the plunger cylinder 12 is disposed inside the housing 18, namely in the tank 16. Thus, the plunger piston 24 can be sealed with respect to the plunger cylinder housing 22 with a simple seal, for example a gap seal. Any leakage from the plunger chamber 26 exits directly into the tank 16, so that no special means for preventing leakage are necessary.

[0053] The hydraulic locking device 10 further includes a rotary shaft 34 extending through the housing 18. Specifically, the rotary shaft 34 extends through the main body 36 and through the cover 38 such that one end of the rotary shaft 34 protrudes from the housing 18 on either side thereof. The rotary shaft 34 is sealed with respect to the housing 18 and the tank 16, respectively, and a relatively simple seal is sufficient since only atmospheric pressure prevails in the tank 16. As shown, a square is provided at each end of the rotary shaft 34 to connect the rotary shaft to further parts in a rotationally fixed manner, cf. FIG. 10. Of course, other possibilities can also be provided here to connect the rotary shaft 34 to the further parts.

[0054] The rotary shaft 34 defines a first axis of rotation D1. The plunger cylinder housing 22 is also rotatably disposed within the housing 18. As shown, the plunger cylinder housing 22 is rotatably mounted about a second axis of rotation D2 on the base body 36 and the cover 38. The second axis of rotation D2 is arranged in parallel to the first axis of rotation D1.

[0055] A lever 40 is disposed within the housing 18 or the tank 16. The lever 40 has a shaft coupling portion 42 at one end thereof and a piston coupling portion 44 at the other end thereof. The shaft coupling portion 42 is non-rotatably connected to the rotary shaft 34, and the piston coupling portion 44 is rotatably connected to the end of the plunger piston 24 protruding from the plunger cylinder housing 22.

[0056] When the rotary shaft 34 rotates about the first axis of rotation D1, the rotary motion is translated into a linear motion of the plunger piston 24 by the rotatable support of the plunger cylinder housing 22 about the second axis of rotation D2 and the lever 40. As shown, the rotary shaft 34 is rotatable between a first end position EP1 (cf. FIG. 7) and a second end position EP2 (cf. FIG. 8). For example, the first end position EP1 may correspond to a fully open position of the exoskeleton joint 50 and the second end position EP2 may correspond to, for example, a fully closed end position EP2 of the exoskeleton joint 50.

[0057] In the first end position EP1 of the rotary shaft 34, the plunger piston 24 is substantially fully extended. Upon rotation of the rotary shaft 34 from the first end position EP1 toward the second end position EP2, the plunger piston 24 retracts and the plunger cylinder housing 22 rotates about the second axis of rotation D2. The plunger piston 24 retracts until a dead point position is reached between the first end position EP1 and the second end position EP2. At this dead point position, the plunger piston 24 is fully retracted although the rotary shaft 34 is not yet in the second end position EP2. Upon further rotation of the rotary shaft 34 about the first axis of rotation D1 from the dead point position toward the second end position EP2, the plunger piston 24 extends again until it is again substantially extended when the rotary shaft 34 is at the second end position EP2. Because of this stroke reversal over the complete movement cycle between the first end position EP1 and the second end position EP2, a particularly compact plunger cylinder 12 can be used. FIG. 9 shows the various positions of the lever 40, the plunger piston 24 and the plunger cylinder housing 22.

[0058] As can be seen from the partial sectional view shown in FIG. 11 (the switching valve 20 is not shown in sectional view), the check valve 28 is disposed in the plunger piston 24. For this purpose, the plunger piston 24 has an axial opening 46 for receiving the check valve 28. One end of the axial opening 46 communicates with the plunger chamber 26, and the other end opens into a bore 48 which passes radially through the plunger piston 24 and communicates with the tank 16. When the switching valve 20 is in the blocking position SS, hydraulic fluid can be sucked through the axial opening 46 into the plunger chamber 26 via the bore 48 and the check valve 28, so that extension of the plunger piston 24 is still possible.

[0059] FIGS. 10 and 11 show an exoskeleton joint 50 with a hydraulic locking device 10 according to the invention. The exoskeleton joint 50 shown is an exoskeleton knee joint. As shown, a thigh 54 of an exoskeleton is received in the first receptacle 52. Further, the exoskeleton knee joint 50 includes a second receptacle 56 that is movably mounted to the housing 18 via a four-bar link 58. A lower leg 60 of the exoskeleton is fixed to the second receptacle 56 in this embodiment.

[0060] The four-bar linkage 58 includes a first leg 62 having one end non-rotatably connected to the rotary shaft 34 and the other end rotatably connected to the second receptacle 56. Further, the four-bar linkage 58 includes a second leg 64 rotatably connected at one end to the housing 18 and rotatably connected at the other end to the second receptacle 56. The four-bar linkage 58 allows the pivot point between the thigh 54 and the lower leg 60 to be offset from the housing 18 and to be optimally selected from an anatomical standpoint.

LIST OF REFERENCE SIGNS

[0061] 10 hydraulic locking device [0062] 12 plunger cylinder [0063] 14 line arrangement [0064] 16 tank [0065] 18 housing [0066] 20 switch valve [0067] 22 plunger cylinder housing [0068] 23 biasing element [0069] 24 plunger piston [0070] 26 plunger chamber [0071] 27 actuating device [0072] 28 check valve [0073] 30 branch line [0074] 32 pressure relief valve [0075] 34 rotary shaft [0076] 36 base body [0077] 38 cover [0078] 40 lever [0079] 42 shaft coupling portion [0080] 44 piston coupling portion [0081] 46 axial opening [0082] 48 bore [0083] 50 exoskeleton joint/exoskeleton knee joint [0084] 52 first receptable [0085] 54 thigh [0086] 56 second receptable [0087] 58 four-bar linkage [0088] 60 lower leg [0089] 62 first leg [0090] 64 second leg [0091] 100 hydraulic locking device [0092] 102 hydraulic cylinder/differential cylinder [0093] 104 line arrangement [0094] 106 accumulator/tank [0095] 108 cylinder housing [0096] 110 piston [0097] 112 piston chamber [0098] 114 rod chamber [0099] 116 first branch [0100] 118 second branch [0101] 120 switching valve [0102] 122 short-circuit line [0103] 124 check valve [0104] D1 first axis of rotation [0105] D2 second axis of rotation [0106] EP1 first end position [0107] EP2 second end position [0108] FS release position [0109] SS blocking position