HYDRAULIC FLOW CONTROL

Description

FIELD

[0001] The present invention generally relates to hydraulics and, more particularly, to a hydraulic fluid system.BACKGROUND

[0002] Existing applications that use magneto-rheological (MR) fluid to manipulate the fluid pressure relationship in a hydraulic fluid system are typically limited to applications compatible with certain MR fluid properties. MR fluid has a high weight / density and includes ferromagnetic particles. Various aerospace applications prefers recirculation of hydraulic fluid that is void of any contaminants and provides the relatively low fluid weight. CN 109 941 902 A and EP 148 200 A each respectively discloses a hydraulic fluid system according to the preamble of claim 1.SUMMARY

[0003] According to the invention, there is provided a hydraulic fluid system according to claim 1. Various preferred embodiments are defined in the dependent claims. Both the configuration of such a hydraulic fluid system and the operational characteristics of such a hydraulic fluid system are within the scope of this Summary.

[0004] [deleted]A hydraulic fluid circuit may be fluidly connected with the hydraulic motor. The magneto-rheological fluid (e.g., including ferromagnetic particles) of the MRF brake may be fluidly isolated from this hydraulic fluid circuit. A static or fixed quantity of the magneto-rheological fluid may be contained within the MRF brake. The MRF brake may be configured such that magneto-rheological fluid is not recirculated from outside the MRF brake, into / through the MRF brake, out of the MFB brake, and then back into the MRF brake (e.g., no exiting and re-entering of magneto-rheological fluid from and back into the MRF brake).

[0005] The MRF brake may include a rotor (e.g., rotatable) that is disposed within the magneto-rheological fluid, whereby this rotor may be interconnected with the output of the hydraulic motor. An electrical control signal to the MRF brake (e.g., to a coil) may be used to control the viscosity of the magneto-rheological fluid, which in turn may control a braking torque exerted by the MRF brake on the output of the hydraulic motor.

[0006] The hydraulic motor and MRF brake may be of an integrated configuration. A common housing assembly may contain the hydraulic motor and the MRF brake. The hydraulic motor may be disposed within a motor housing, the MRF brake may be disposed in a brake housing, and a housing may be disposed between and engage each of the motor housing and the brake housing.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic of a hydraulic fluid system that uses a hydraulic motor and separate MRF brake; Figure 1A is an enlarged view of the MRF brake used by the hydraulic fluid system shown in Figure 1; Figure 2 is a schematic of a hydraulic fluid system that uses multiple MRF brakes, in accordance with an embodiment of the invention; and Figure 3 is a schematic of a hydraulic fluid system that uses an integrated hydraulic motor and MRF brake, in accordance with various embodiments. DETAILED DESCRIPTION

[0008] A hydraulic fluid system is illustrated in Figure 1 and is identified by reference numeral 10. The hydraulic fluid system 10 includes a hydraulic motor 30 (e.g., a gear pump), an MRF brake 50, and a controller 70. The hydraulic motor 30 and MRF brake 50 are separate components in the case of the hydraulic fluid system 10, and may be disposed in spaced relation to one another. Generally, the MRF brake 50 may be operated to control a magnitude of a braking torque exerted on the hydraulic motor 30, and the magnitude of this braking torque is adjustable. In the case of the hydraulic fluid system 10, the hydraulic motor 30 may be characterized as an adjustable orifice for the hydraulic fluid system 10 (e.g., fluid pressure from one or more devices fluidly connected with the hydraulic motor 30 drive the hydraulic motor 30 (e.g., a gear pump 30), and the MRF brake 50 would in tum be used to control how the hydraulic motor 30 resists the fluid pressure from each such device). The hydraulic motor 30, MRF brake 50, and controller 70 collectively control the flow of the hydraulic fluid 12 within the hydraulic fluid system 10 and the pressure of the hydraulic fluid 12 within the hydraulic fluid system 10. Representative applications of the hydraulic fluid system 10 include a hydraulic damper (e.g., a shimmy damper for nose wheel steering on an aircraft, as an adjustable orifice to control the "free fall" characteristics of hydraulically-actuated landing gear for aircraft, or any other application that would benefit from having a hydraulic fluid restriction (the combination of the hydraulic motor 30 and MRF brake 50) that can be controlled quickly and in real time.

[0009] A hydraulic fluid 12 of any appropriate type is directed through a hydraulic fluid input line 14 and into an input port 34 of a motor housing 32 of the hydraulic motor 30. A hydraulic fluid output line 18 extends from an output port 36 of the motor housing 32. The hydraulic fluid input line 14, the hydraulic fluid output line 18, or both, may be interconnected with a hydraulic fluid source, such as an accumulator, and one or more other devices. At least one pressure transducer / sensor 16 may be associated with the hydraulic fluid input line 14, at least one pressure transducer / sensor 20 may be associated with the hydraulic fluid output line 18, or both.

[0010] The hydraulic motor 30 may include an output gear 38 and an idler gear 40. Hydraulic fluid 12 that enters the motor housing 32 simultaneously rotates the output gear 38 and idler gear 40. An output shaft 42 may be interconnected and rotate with the output gear 38. The output shaft 42 may also extend to the MRF brake 50.

[0011] The MRF brake 50 is illustrated in Figure 1 and Figure 1A. The MRF brake 50 includes a brake housing 52. The brake housing 52 may be spaced from the motor housing 32. The hydraulic fluid system 10 may also be configured such that the motor housing 32 and brake housing 52 do not share any common housing section.

[0012] The MRF brake 50 includes a magnetic coil 54, a rotor 56, and a rotor shaft 58. The output shaft 42 of the hydraulic motor 30 may be coupled with the rotor shaft 58 of the MRF brake 50 such that the output shaft 42, rotor shaft 58, and rotor 56 collectively rotate at a common rotational speed (with rotor 56 and rotor shaft 58 being rotatable relative to the brake housing 52). A speed transducer / sensor 62 may be associated with the rotor shaft 58 (e.g., to monitor a rotational speed of the rotor shaft 58).

[0013] At least a portion of at least one of the rotor 56 and rotor shaft 58 may be exposed to a magneto-rheological fluid 60, including with the rotor 56 is disposed in the magneto-rheological fluid 60. A fixed quantity of the magneto-rheological fluid 60 may be contained / retained within the brake housing 52. Stated another way, the magneto-rheological fluid 60 may be incorporated so as to not be recirculated through the brake housing 52 (e.g., the magneto-rheological 60 does not flow from a fluid source (e.g., an accumulator) through one or more input ports of the brake housing 52, and then exit the brake housing 52 through one or more output ports and then back to the fluid source during operation of the MRF brake 50).

[0014] The controller 70 may be operatively interconnected with the MRF brake 50 by an electrical signal control line 84 that extends from the controller 70 to the magnetic coil 54 of the MRF brake 50. Generally, an electrical control signal is sent from the controller 70 to the magnetic coil 54 via the signal line 84. Increasing the current of this electrical control signal increases the viscosity of the magneto-rheological fluid 60 in the MRF brake 50, which increases the braking torque applied by the MRF brake 50 to the output shaft 42 of the hydraulic motor 30. Similarly, decreasing the current of this electrical control signal decreases the viscosity of the magneto-rheological fluid 60 in the MRF brake 50, which decreases the braking torque applied by the MRF brake 50 to the output shaft 42 of the hydraulic motor 30.

[0015] A high pressure signal line 72 may extend from the pressure transducer 16 of the hydraulic motor 30 to the controller 70 (an input to the controller 70). A low pressure signal line 74 may extend from the pressure transducer 20 of the hydraulic motor 30 to the controller 70 (an input to the controller 70). A rotational speed signal line 76 may extend from the speed transducer / sensor 62 to the controller 70.

[0016] The controller 70 may be configured to utilize a pressure control logic. The monitored pressure on the input side of the hydraulic motor 30 (via pressure transducer 16) and the monitored pressure on the output side of the hydraulic motor 30 (via pressure transducer 20) may be used to determine a corresponding differential pressure between the input side and output side of the hydraulic motor 30, and this differential pressure may be used to generate an electrical control signal that provides a corresponding braking torque. A data structure 82 (e.g., a look-up table) in memory 80 (e.g., computer-readable) may correlate a certain differential pressure to a braking torque and an associated current for the electrical control signal. An MRF brake driver 78 of the controller 70 may generate and send an electrical control signal to the coil 54 of the MRF brake 50 (via the electrical control signal line 84) that yields the desired differential pressure (between the input side and output side of the hydraulic motor 30) and a corresponding desired braking torque (via producing a certain viscosity of the magneto-rheological fluid 60 via the current of the electrical control signal).

[0017] The controller 70 could also be configured to utilize a flow control logic. The flow rate through the hydraulic motor 30 may be correlated to a differential pressure between the input side of the hydraulic motor 30 (via pressure transducer 16) and the output side of the hydraulic motor 30 (via pressure transducer 20). The data structure 82 (e.g., a look-up table) in memory 80 may correlate a certain rotational speed of the rotor shaft 58 to a braking torque and an associated current for the electrical control signal. The MRF brake driver 78 of the controller 70 may generate and send an electrical control signal to the coil 54 of the MRF brake 50 (via the control signal line 84) that yields a desired rotational speed of the rotor shaft 58 and a corresponding desired braking torque (via producing a certain viscosity of the magneto-rheological fluid 60 via the current of the electrical control signal).

[0018] A hydraulic fluid system in accordance with various embodiments is illustrated in Figure 2 and is identified by reference numeral 90. The hydraulic fluid system 90 includes four motor / brake sets 92a, 92b, 92c, and 92d. The configuration of each of these motor / brake sets 92a, 92b, 92c, and 92d is at least generally in accordance with the discussion presented above regarding Figures 1 and 1A. The motor / brake sets 92a and 92b are disposed in series with one another, the motor / brake sets 92c and 92d are disposed in series with one another, and the motor / brake sets 92a, 92b are collectively disposed in parallel to the motor / brake sets 92c, 92d. The motor / brake sets 92a, 92b, 92c, and 92d in effect define a hydraulic bridge circuit. The output pressure and flow (magnitude and direction) may be controlled by adjusting the individual currents in the coil 54 of the four MRF brakes 50.

[0019] The hydraulic fluid input line 14' extends to the input port 34 of the hydraulic motor 30 of the motor / brake sets 92a, 92c, while the hydraulic fluid output line 18' extends from the output port 36 of the hydraulic motor 30 of the motor / brake sets 92b, 92d. A hydraulic line 94a extends from the output port 36 of the hydraulic motor 30 for the motor / brake set 92a to the input port 34 of the hydraulic motor 30 for the motor / brake set 92b, and also extends to a hydraulic load 96. A hydraulic line 94b extends from the output port 36 of the hydraulic motor 30 for the motor / brake set 92c to the input port 34 of the hydraulic motor 30 for the motor / brake set 92d, and also extends to the hydraulic load 96 (via an electrical control signal via the corresponding signal line 84).

[0020] In the case of the hydraulic fluid system 90, the pressure in the hydraulic fluid input line 14' may be constant, and the pressure in the hydraulic fluid output line 18' may be constant. The motor / brake sets 92a, 92b, 92c, and 92d in the case of the hydraulic fluid system 90 may be used to control the hydraulic load 96. Representative hydraulic loads 96 include without limitation an aircraft component. The hydraulic load 96 may be a hydraulic actuator (e.g., a wheel brake actuator of an aircraft to control brake torque), a hydraulic (rotary) motor that drives an actuator, a vehicle, or any other device that requires the conversion of hydraulic power (the product of flow and pressure) into another form of mechanical (motive) energy.

[0021] A hydraulic fluid system in accordance with various embodiments is illustrated in Figure 3 and is identified by reference numeral 100. Generally, a hydraulic motor or gear pump (e.g., hydraulic motor 30) and an MRF brake (e.g., MRF brake 50) are integrated into a common housing assembly 102. This housing assembly 102 includes a gear pump housing 104, a brake housing 120, and a cover plate 122. The brake housing 120 includes components for an MRF brake, and furthermore closes an open end of the gear pump housing 104. The cover plate 122 seals an open end of the brake housing 120. The gear pump includes an output gear 106 and an idler gear 110. An idler gear shaft 112 is associated and rotates with the idler gear 110. A shaft 108 is associated and rotates with each of the output gear 106 (gear pump) and a rotor 126 (MRF brake). Bearings 114 may rotatably support the shaft 108 and the idler gear shaft 112. A seal 116 may be mounted on the shaft 108 adjacent to the brake housing 120 and into which the shaft 108 extends. A magnetic coil 124 may be disposed within the brake housing 120, along with a magneto-rheological fluid 128 in which the rotor 126 is disposed. An electrical control signal to the magnetic coil 124 may be used to control the braking torque exerted by the magneto-rheological fluid 128 on the rotor 126 (and any portion of the shaft 108 that also interfaces with this magneto-rheological fluid 128. Increasing the current of the electrical control signal to the magnetic coil 124 increases the viscosity of the magneto-rheological fluid 128, and thereby the increases the magnitude of the braking torque exerted by the magneto-rheological fluid 128 on the rotor 126. Decreasing the current of the electrical control signal to the magnetic coil 124 decreases the viscosity of the magneto-rheological fluid 128, and thereby decreases the magnitude of the braking torque exerted by the magneto-rheological fluid 128 on the rotor 126.

[0022] Any feature of any other various aspects addressed in this disclosure that is intended to be limited to a "singular" context or the like will be clearly set forth herein by terms such as "only," "single," "limited to," or the like. Merely introducing a feature in accordance with commonly accepted antecedent basis practice does not limit the corresponding feature to the singular. Moreover, any failure to use phrases such as "at least one" also does not limit the corresponding feature to the singular. Use of the phrase "at least substantially", "at least generally," or the like in relation to a particular feature encompasses the corresponding characteristic and insubstantial variations thereof (e.g., indicating that a surface is at least substantially or at least generally flat encompasses the surface actually being flat and insubstantial variations thereof). Finally, a reference of a feature in conjunction with the phrase "in one embodiment" does not limit the use of the feature to a single embodiment.

[0023] The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the appended claims.

Claims

1. A hydraulic fluid system (10), comprising: a hydraulic motor (30) comprising an output; a magneto-rheological fluid "MRF" brake (50) interconnected with said output of said hydraulic motor (30), said MRF brake (50) comprising a magneto-rheological fluid; wherein said hydraulic motor and said MRF brake define a first set; the system characterized by a second hydraulic motor and a second MRF brake operatively interconnected with said second hydraulic motor and that defines a second set, and wherein said first set and said second set are connected in series; a third hydraulic motor and a third MRF brake operatively interconnected with said third hydraulic motor and that defines a third set; and a fourth hydraulic motor and a fourth MRF brake operatively interconnected with said fourth hydraulic motor and that defines a fourth set, wherein said third set and said fourth set are connected in series, and wherein said first set and said second set are collectively connected in parallel with said third set and said fourth set.

2. The hydraulic fluid system of claim 1, wherein said hydraulic motor comprises an idler gear (40) and an output gear (38), and wherein said MRF brake is interconnected with said output gear.

3. The hydraulic fluid system of claim 1 or 2, further comprising: a hydraulic fluid circuit fluidly connected with said hydraulic motor (30), wherein said magneto-rheological fluid of said MRF brake is fluidly isolated from said hydraulic fluid circuit.

4. The hydraulic fluid system of any preceding claim, wherein said MRF brake comprises a magnetic coil (54), wherein said MRF brake comprises an electrical control signal input to said magnetic coil, and optionally wherein an amount of current flowing through said magnetic coil of said MRF brake corresponds with a viscosity of said magneto-rheological fluid of said MRF brake.

5. The hydraulic fluid system of any preceding claim, wherein said MRF brake comprises a controller, wherein an input to said controller is selected from the group consisting of a differential pressure of said hydraulic motor and an operational speed of said hydraulic motor.

6. The hydraulic fluid system of any preceding claim, wherein said MRF brake comprises a rotatable rotor (56) disposed within said magneto-rheological fluid.

7. The hydraulic fluid system of any preceding claim, wherein said hydraulic motor comprises a motor housing (32) and said MRF brake comprises a brake housing (52), and wherein said motor housing is completely separate from said brake housing.

8. The hydraulic fluid system of any preceding claim, further comprising a common hydraulic load fluidly connected with each of said hydraulic motor, said second hydraulic motor, said third hydraulic motor, and said fourth hydraulic motor.

9. The hydraulic fluid system of claim 8, wherein said common hydraulic load is an aircraft component.