Fluid Actuator with Limit Sensors and Fluid Limit Valves

Abstract

A fluid actuator with fluid limit valves (550, 551) and optional adjustable mechanical limits enables the construction of fluid linkages which are able to completely replace mechanical linkages. In a fluid circuit comprising of two or more fluid actuators, the pistons (102) of the fluid actuators can become uncorrelated when fluid leakage occurs. At the piston (102) extension and retraction limits, fluid limit valves (550, 551) open. The open fluid limit valves (550, 551) allow fluid to bypass pistons (102) and/or allow fluid from an external source to compensate the fluid leakage. The fluid bypassing pistons (102) at their extension or retraction limit and/or externally supplied fluid forces the uncorrelated pistons (102) to reach their extension or retraction limit as well. The fluid actuator with optional adjustable mechanical limits have one or more additional pistons (686, 688), which have an adjustable separation from the main piston (102) or end of cylinder. The fluid actuator with fluid limit valves (550, 551) and optional adjustable mechanical limits enables mechanical linkages to be replaced by fluid circuits composed of the fluid actuators.

Description

DRAWINGS—FIGURES

FIG. 1 Isometric view of a Prior Art Fluid Actuator.

FIG. 2 Cross Section view of the Prior Art Fluid Actuator shown in FIG. 1 taken along Cutting Plane A-A.

FIG. 3 Isometric view of the Base Portion of the Prior Art Fluid Actuator shown in FIG. 1

FIG. 4 Cross Section view of the Base Portion of the Prior Art Fluid Actuator shown in FIG. 2 taken along Cutting Plane B-B.

FIG. 5 Isometric view of the Base Portion of the Fluid Actuator with an Integrated Fluid Limit Valve that has No Moving Parts.

FIG. 6 Cross Section view of the Base Portion of the Fluid Actuator with an Integrated Fluid Limit Valve that has No Moving Parts shown in FIG. 5 taken along Cutting Plane C-C.

FIG. 7 Isometric view of the Base Portion of the Fluid Actuator with a Fluid Limit Valve integrated into the Piston.

FIG. 8 Cross Section view of the Base Portion of the Fluid Actuator with a Fluid Limit Valve integrated into the Piston shown in FIG. 7 taken along Cutting Plane D-D.

FIG. 9 Isometric view of the Base Portion of the Fluid Actuator with a Fluid Limit Valve integrated in the End Cap.

FIG. 10 Cross Section view of the Base Portion of the Fluid Actuator with a Fluid Limit Valve integrated in the End Cap shown in FIG. 9 taken along Cutting Plane E-E.

FIG. 11 Isometric view of the Hydro Pneumatic Cylinder with Adjustable Mechanical Limits.

FIG. 12 a Cross Section of Hydraulic Cylinder with Adjustable Mechanical Limits shown in FIG. 11 taken along Cutting Plane F-F

FIG. 12 b Cross Section of Hydro Pneumatic Cylinder with Adjustable Mechanical Limits shown in FIG. 11 taken along Cutting Plane F-F

FIG. 13 a Detailed Side Cross Section of Fluid Limit Valve shown in FIG. 12a, FIG. 12b which is taken along Cutting Plane F-F

FIG. 13 b Detailed Side Cross Section of Fluid Limit Valve with External Fluid Leakage Correction Supply shown in FIG. 12a, FIG. 12b which is taken along Cutting Plane F-F

FIG. 14 Basic fluid linkage utilizing the Fluid Limit Valve With Moving Parts

FIG. 15 Basic fluid linkage utilizing the Fluid Limit Valve Without Moving Parts

FIG. 16 Fluid Actuators with External Mechanical Limit Stops

Claims

1. A fluid actuator comprising a. a cylinder,b. a movable main piston inside said cylinder,c. one or more fluid limit valves that open to allow fluid to bypass said main piston when limit sensors are activated,d. one or more said limit sensors, such that when said main piston is extended to its extension limit and/or when said piston is retracted to its retraction limit, it activates said limit sensors for each extension or retraction limit, and such that said fluid limit valves allow fluid to bypass said main piston to prevent said main piston of said fluid actuator from extending or retracting too hard against the cylinder ends,whereby said main piston of said fluid actuator is prevented from extending or retracting too hard against the cylinder ends, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuator is increased.

2. The fluid actuator of claim 1 further including additional movable pistons inside said cylinder, such that the separation between said additional pistons and said main piston or end of said cylinder can be adjusted by the amount of incompressible fluid between said additional pistons and said main piston or end of said cylinder, such that when said main piston is extended to its extension limit and/or when said main piston is retracted to its retraction limit, a said piston activates limit sensors for each extension or retraction limit, and such that said fluid limit valves allow fluid to bypass said main piston to prevent said main piston of said fluid actuator from extending or retracting too hard against said cylinder ends, whereby the extension and retraction limits of said main piston are adjustable by the amount of fluid between said additional pistons and said main piston or end of said cylinder.

3. The fluid actuator of claim 1 further including a. an additional cylinder,b. a primary movable piston inside said additional cylinder,c. an optional additional movable piston inside said additional cylinder, such that the separation between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder can be adjusted by the amount of incompressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder, and such that when said main piston is extended to its extension limit and/or when said main piston is retracted to its retraction limit, said primary piston inside said additional cylinder is also at its extension limit and/or said primary piston inside said additional cylinder is also at its retraction limit, and such that a said piston inside said additional cylinder activates limit sensors associated with said additional cylinder for each extension or retraction limit, and such that said fluid limit valves allow fluid to bypass said main piston to prevent said main piston from extending or retracting too hard against said cylinder ends,whereby the extension and retraction limits of said main piston are adjustable by the amount of fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder.

4. The fluid actuator of claim 1 further including additional movable pistons inside said cylinder, such that the force between said additional pistons and said main piston or end of said cylinder can be adjusted by the amount of compressible fluid between said additional pistons and said main piston or end of said cylinder, and such that when said main piston approaches its extension limit and/or when said main piston approaches its retraction limit, a said piston activates said limit sensors accordingly to the force applied by said piston and said fluid limit valves open in accordance to the degree which said limit sensors am are activated, andsuch that fluid flowing through said fluid limit valves reduces the extension speed of said main piston approaching its extension limit in accordance to the degree which said limit sensors are activated, andsuch that fluid flowing through said fluid limit valves reduces the retraction speed of said main piston approaching its retraction limit in accordance to the degree which said limit sensors are activated, andsuch that the applied extension force on said main piston approaching its extension limit is reduces in accordance to the degree which said limit sensors are activated,such that the applied retraction force on said main piston approaching its retraction limit is reduces in accordance to the degree which said limit sensors are activated, andsuch that prevent said pistons from extending or retracting too hard against said cylinder ends,whereby the extension and retraction speed as said main piston approaching the extension or retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said additional pistons and said main piston or end of said cylinder, andwhereby the applied extension and retraction force on said main piston approaching extension and retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said additional pistons and said main piston or end of said cylinder.

5. The fluid actuator of claim 1 further including a. an additional cylinder,b. a primary movable piston inside said additional cylinder,c. an optional additional movable piston inside said additional cylinder,such that the force between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder can be adjusted by the amount of compressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder,and such that when said main piston approaches its extension limit and/or when said main piston approaches its retraction limit, said primary piston inside said additional cylinder approaches its extension limit and/or when said primary piston inside said additional cylinder also approaches its retraction limit, andsuch that a said piston inside said additional cylinder activates said limit sensors associated with said additional cylinder accordingly to the force applied by said piston inside said additional cylinder and said fluid limit valves open in accordance to the degree which said limit sensors associated with said additional cylinder are activated, andsuch that when said main piston approaches its extension limit and/or when said main piston approaches to its retraction limit, said primary piston inside said additional cylinder also approaches its extension limit and/or when said primary piston inside said additional cylinder also approaches to its retraction limit, andsuch that a said piston inside said additional cylinder activates limit sensors associated with said additional cylinder accordingly to the force applied by said piston inside said additional cylinder and the said fluid limit valves open in accordance to the degree the limit sensors associated with said additional cylinder are activated, andsuch that fluid flowing through said fluid limit valves reduces the extension speed of said main piston approaching its extension limit in accordance to the degree which said limit sensors associated with said additional cylinder are activated, andsuch that fluid flowing through said fluid limit valves reduces the retraction speed of said main piston approaching its retraction limit in accordance to the degree which said limit sensors associated with said additional cylinder are activated, andsuch that the applied extension force on said main piston approaching its extension limit is reduces in accordance to the degree which said limit sensors associated with said additional cylinder are activated,such that the applied retraction force on said main piston approaching its retraction limit is reduces in accordance to the degree which said limit sensors associated with said additional cylinder are activated, andsuch that prevent said pistons from extending or retracting too hard against said cylinder ends,whereby the extension and retraction speed as said main piston approaching the extension or retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder, andwhereby the applied extension and retraction force on said piston approaching extension and retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder.

6. The fluid actuator of claim 1, 2, 3, and such that when incompressible fluid flows from a fluid source into a fluid actuator and incompressible fluid flows out of the said fluid actuator into another said fluid actuator through fluid conduits for connecting said fluid actuators with possible intermediary fluid control valves and fluid pumps, then said incompressible fluid flows from said fluid source through said fluid limit valves bypassing said pistons of said fluid actuators to compensate for incompressible fluid loss at limit positions of said pistons of fluid actuators, and said pistons of said fluid actuators can be put in the correct relative positions,whereby when two or more said fluid actuators are connected, they will have their piston motion forcibly correlated by the said fluid actuators operating one or more said fluid limit valves to accurately position the said pistons of said fluid actuators, andwhereby incompressible fluid loss is compensated for at limit positions of said pistons of said fluid actuators, and said pistons of said fluid actuators will be put in the correct relative positions, andwhereby the need for immediate incompressible fluid loss maintenance is reduced or eliminated, andwhereby the detected incompressible fluid loss provides an indication of when and where incompressible fluid loss maintenance is required, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

7. The fluid actuator of claim 1, 2, 3, further including an additional fluid inlet into said fluid limit valves, and such that when incompressible fluid flows out of a fluid actuator into another said fluid actuator through fluid conduits for connecting said fluid actuators with possible intermediary fluid control valves and fluid pumps, then incompressible fluid flows into said fluid limit valves from the additional fluid inlet to compensate for incompressible fluid loss at limit positions of said pistons of said fluid actuators, and said pistons of said fluid actuators can be put in the correct relative positions,whereby when two or more said fluid actuators are connected, they will have their piston motion forcibly correlated by the said fluid actuators operating one or more said fluid limit valves to accurately position the said pistons of said fluid actuators, andwhereby a fluid source is not required in the circuit to compensate for incompressible fluid loss, incompressible fluid loss is compensated through the additional fluid inlet of said fluid limit valves,whereby incompressible fluid loss is compensated for at limit positions of said pistons of said fluid actuators, and said pistons of said fluid actuators will be put in the correct relative positions, andwhereby the need for immediate incompressible fluid loss maintenance is reduced or eliminated, andwhereby the detected incompressible fluid loss provides an indication of when and where incompressible fluid loss maintenance is required, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

8. A fluid actuator, comprising a. a cylinder,b. a movable piston inside said cylinder,c. bypass fluid outlets, such that when said piston is extended to its extension limit and/or said piston is retracted to its retraction limit, said piston passes over said bypass fluid outlets allowing fluid to bypass said piston, andsuch that when said piston is extended to its extension limit and/or when said piston is retracted to its retraction limit, it allows fluid to bypass said piston, andsuch that preventing said piston from extending or retracting too hard against said cylinder ends,whereby said piston is prevented from extending or retracting too hard against said cylinder ends, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuator is increased.

9. The fluid actuator of claim 8, and such that when incompressible fluid flows from a fluid source into a fluid actuator and incompressible fluid flows out of said fluid actuator into another said fluid actuator through fluid conduits for connecting said fluid actuators with possible intermediary fluid control valves and fluid pumps, then incompressible fluid flows from said fluid source through said bypass fluid outlets bypassing said piston to compensate for fluid loss at limit positions of said pistons of said fluid actuators, and said pistons of said fluid actuators can be put in the correct relative positions,whereby when two or more said fluid actuators are connected, they will have their piston motion forcibly correlated by the said fluid actuators operating one or more said fluid limit valves to accurately position the said pistons of said fluid actuators, andwhereby incompressible fluid loss is compensated for at limit positions of said pistons of said fluid actuators, and said pistons of said fluid actuators will be put in the correct relative positions, andwhereby the need for immediate incompressible fluid loss maintenance is reduced or eliminated, andwhereby the detected incompressible fluid loss provides an indication of when and where incompressible fluid loss maintenance is required, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

10. A method of preventing the main piston of a fluid actuator from extending or retracting too hard against the cylinder ends, comprising the steps of: a. forcing the main piston inside the cylinder of said fluid actuator to extend or retract with fluid,b. activating limit sensors of said fluid actuator when said main piston inside said cylinder of said fluid actuator extends to its extension limit or retracts to its retraction limit,c. opening fluid limit valves to allow fluid to bypass said main piston when said limit sensors are activated,d. allowing fluid to bypass said main piston to prevent said main piston of said fluid actuator from extending or retracting too hard against the cylinder ends,whereby said main piston of said fluid actuators are prevented from extending or retracting too hard against said cylinder ends, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

11. The method of claim 10, further providing adjustable said main piston extension and retraction limits, comprising the additional steps of: a. increasing or decreasing the amount of incompressible fluid between said additional pistons and said main piston or end of said cylinder, such that the separation between said main piston and said additional pistons is adjusted,b. activating limit sensors when said main piston is at its extension or retraction limit,whereby the extension and retraction limits of said main piston are adjustable by the amount of fluid between said additional pistons and said main piston or end of said cylinder.

12. The method of claim 10, further providing adjustable said main piston extension and retraction limit, comprising the additional steps of: a. employing an additional cylinder containing a primary movable piston inside said additional cylinder,b. optionally employing an additional movable pistons inside said additional cylinder,c. increasing or decreasing the amount of incompressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder, such that the separation between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder is adjusted,d. extending said main piston to its extension limit and/or retracting said main piston to its retraction limit, causes said primary piston inside said additional cylinder also to extend to its extension limit or retract to its retraction limit,e. activating limit sensors associated with said additional cylinder when said primary piston inside said additional cylinder is at its extension or retraction limit,whereby the mechanical extension and retraction limits of said main piston are adjustable by the amount of fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder.

13. A method of claim 10, further including a means of reducing said main piston extension and retraction speed and applied extension and retraction force on said main piston approaching extension and retraction limits, comprising the steps of: a. increasing or decreasing the amount of compressible fluid between said additional pistons and said main piston or end of said cylinder, such that the force between said additional pistons and said main piston or end of said cylinder is adjusted,b. extending said main piston towards its extension limit and/or retracting said main piston towards its retraction limit, causes a said piston to activate said limit sensors accordingly to the force applied by said piston,c. opening said fluid limit valves in accordance to the degree that said limit sensors are activated,d. bypassing fluid though said fluid limit valves in accordance to the degree said fluid limit valves are open,e. reducing the extension speed of said main piston approaching its extension limit in accordance to the amount of fluid bypassing through said fluid limit valves,f. reducing the retraction speed of said main piston approaching its retraction limit in accordance to the amount of fluid bypassing through said fluid limit valves,g. reducing the applied extension force on said main piston approaching its extension limit in accordance to the degree that said limit sensors are activated,h. reducing the applied retraction force on said main piston approaching its retraction limit in accordance to the degree that said limit sensors are activated,i. preventing said pistons from extending or retracting too hard against said cylinder ends,whereby the extension and retraction speed as said main piston approaching the extension or retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said additional pistons and said main piston or end of said cylinder, andwhereby the applied extension and retraction force on said main piston approaching extension and retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said additional pistons and said main piston or end of said cylinder.

14. A method of claim 10, further including a means of reducing said main piston extension and retraction speed and applied extension and retraction force on said main piston approaching extension and retraction limits, comprising the steps of: a. employing an additional cylinder containing a primary movable piston inside said additional cylinder,b. optionally employing an additional movable pistons inside said additional cylinder,c. increasing or decreasing the amount of incompressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder, such that the force between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder is adjusted,d. extending said main piston towards its extension limit and/or retracting said main piston towards its retraction limit, causes said primary piston inside said additional cylinder also to extend towards its extension limit or retract towards to its retraction limit,e. extending said primary piston inside said additional cylinder towards its extension limit and/or retracting said primary piston inside said additional cylinder towards its retraction limit, causes a said piston inside said additional cylinder to activate said limit sensors associated with said additional cylinder accordingly to the force applied by said piston,f. opening said fluid limit valves in accordance to the degree that said limit sensors associated with said additional cylinder are activated,g. bypassing fluid though said fluid limit valves in accordance to the degree said fluid limit valves are open,h. reducing the extension speed of said main piston approaching its extension limit in accordance to the amount of fluid bypassing through said fluid limit valves,i. reducing the retraction speed of said main piston approaching its retraction limit in accordance to the amount of fluid bypassing through said fluid limit valves,j. reducing the applied extension force on said main piston approaching its extension limit in accordance to the degree that said limit sensors associated with said additional cylinder are activated,k. reducing the applied retraction force on said main piston approaching its retraction limit in accordance to the degree that said limit sensors associated with said additional cylinder are activated,l. preventing said pistons from extending or retracting too hard against said cylinder ends,whereby the extension and retraction speed as said main piston approaching the extension or retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder, andwhereby the applied extension and retraction force on said piston approaching extension and retraction limits is reduced by an adjustable amount according to the amount of compressible fluid between said primary piston inside said additional cylinder and the one end of said additional cylinder or said optional piston inside said additional cylinder.

15. A method of preventing the piston of a fluid actuator from extending or retracting too hard against the cylinder ends, comprising the steps of: a. locating fluid bypass outlets near the extension and retraction limits of said piston, such that said piston approaching its extension limit passes over extension limiting fluid bypass outlets shortly before reaching its extension limit and/or said piston approaching its retraction limit passes over retraction limiting fluid bypass outlets shortly before reaching its retraction limit,b. forcing said piston inside the cylinder of said fluid actuator to extend or retract with fluid,c. extending said piston passed extension limiting fluid bypass outlets or retracting said piston passed retraction limiting fluid bypass outlets,d. allowing fluid to bypass said piston by flowing through bypass outlets to prevent said piston from extending or retracting too hard against the cylinder endswhereby said piston of said fluid actuators are prevented from extending or retracting too hard against said cylinder ends, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

16. A method of claim 15 further including a means of detecting and correcting fluid loss at certain positions of said pistons when two or more said fluid actuators are connected, comprising the steps of: a. forcing the main piston of a said fluid actuator to extend or retract with incompressible fluid from a fluid source,b. extending or retracting said main piston forces incompressible fluid out of said fluid actuator into another said fluid actuator through fluid conduits for connecting said fluid actuators with possible intermediary fluid control valves and fluid pumps,c. extending said piston passed extension limiting fluid bypass outlets or retracting said piston passed retraction limiting fluid bypass outlets,d. allowing incompressible fluid from said fluid source to bypass said main piston of said fluid actuator to compensate for fluid loss, such that said main pistons of all said fluid actuators put in the correct relative positions,whereby when two or more said fluid actuators are connected, they will have their pistons motion forcibly correlated by the said fluid actuators operating one or more said fluid limit valves to accurately position the said pistons, andwhereby incompressible fluid loss is compensated for at certain positions of said pistons, and said pistons will be put in the correct relative positions, andwhereby the need for immediate incompressible fluid loss maintenance is reduced or eliminated, andwhereby the detected incompressible fluid loss provides an indication of when and where fluid loss maintenance is required, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

17. A method of claim 10, 11, 12 further including a means of detecting and correcting fluid loss at certain positions of said pistons when two or more said fluid actuators are connected, comprising the steps of: a. forcing the main piston of a said fluid actuator to extend or retract with incompressible fluid from a fluid source,b. extending or retracting said main piston forces incompressible fluid out of said fluid actuator into another said fluid actuator through fluid conduits for connecting said fluid actuators with possible intermediary fluid control valves and fluid pumps,c. activating limit sensors of said fluid actuator when said main piston of said fluid actuator extends to its extension limit or retracts to its retraction limit,d. opening fluid limit valves of said fluid actuator to allow fluid to bypass said main piston of said actuator when said limit sensors of said fluid actuator are activated,e. allowing incompressible fluid from said fluid source to bypass said main piston of said fluid actuator to compensate for fluid loss, such that said main pistons of all said fluid actuators put in the correct relative positions,whereby when two or more said fluid actuators are connected, they will have their pistons motion forcibly correlated by the said fluid actuators operating one or more said fluid limit valves to accurately position the said pistons, andwhereby incompressible fluid loss is compensated for at certain positions of said pistons, and said pistons will be put in the correct relative positions, andwhereby the need for immediate incompressible fluid loss maintenance is reduced or eliminated, andwhereby the detected incompressible fluid loss provides an indication of when and where fluid loss maintenance is required, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.

18. A method of claim 10, 11, 12 further including a means of detecting and correcting fluid loss at certain positions of said pistons when two or more said fluid actuators are connected, comprising the steps of: a. employing a source of incompressible fluid connected to a fluid inlet added into said fluid limit valvesb. extending or retraction said main piston of a said fluid actuator,c. extending or retracting said main piston forces incompressible fluid out of said fluid actuator into another said fluid actuator through fluid conduits for connecting said fluid actuators with possible intermediary fluid control valves and fluid pumps,d. activating limit sensors of said fluid actuator when said main piston of said fluid actuator extends to its extension limit or retracts to its retraction limit,e. opening fluid limit valves of said actuator when said limit sensors of said fluid actuator are activated,f. allowing incompressible fluid from the source of incompressible fluid connected to a fluid inlet added into said fluid limit valves to compensate for incompressible fluid loss, such that said main pistons of all said fluid actuators put in the correct relative positions,whereby a fluid source is not required in the circuit to compensate for incompressible fluid loss, incompressible fluid loss is compensated through the additional fluid inlet of said fluid limit valves,whereby when two or more said fluid actuators are connected, they will have their pistons motion forcibly correlated by the said fluid actuators operating one or more said fluid limit valves to accurately position the said pistons, andwhereby incompressible fluid loss is compensated for at certain positions of said pistons, and said pistons will be put in the correct relative positions, andwhereby the need for immediate incompressible fluid loss maintenance is reduced or eliminated, andwhereby the detected incompressible fluid loss provides an indication of when and where fluid loss maintenance is required, andwhereby the need for maintenance is reduced and the lifetime of said fluid actuators is increased.