Underwater rotary hydraulic proportional valve

Abstract

According to the technical scheme, the underwater rotary hydraulic proportional valve is characterized in that the underwater rotary hydraulic proportional valve comprises a valve body, a steel sleeve, a shell, a coil, a magnet yoke, a stator iron core, an inner end cover, a sealing ring a, a dustproof screw, a sealing ring b, a rotary transformer, a permanent magnet, a sealing ring c, a valve sleeve, a valve element, a bearing and a sealing ring d, and is characterized in that a plurality of hydraulic oil ports are formed in the valve body; the hydraulic oil port is communicated with the oil port through the multiple valve cavities, the shell is installed at one end of the valve body, a driving cavity is formed in the shell, and the valve element and a rotating shaft of the motor are integrated. The wet-type limited angle torque motor is adopted to drive the rotary valve and the valve element to rotate, a motion conversion device is omitted, the valve element and the valve sleeve rotate relatively, friction force is small, the anti-pollution capacity is high, the axial leakage problem does not exist, a motor shaft of the limited angle torque motor can rotate within a limited angle range, and the advantages of being convenient to control, large in torque density, high in reliability and the like are achieved. And the method is simple and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of electro-hydraulic servo control engineering, and in particular to an underwater rotary hydraulic proportional valve. Background Art

[0002] As the world pays more and more attention to marine resources, the mineral, energy and biological resources in deep-sea areas have attracted many countries and scientific research institutions to develop them. In deep-sea operations, such as deep-sea oil and gas exploitation, mineral collection and observation equipment operation, hydraulic systems play an important role. The system needs to accurately control deep-sea robotic arms, seabed drilling equipment and submersible propulsion and attitude adjustment devices to cope with extreme deep-sea environments.

[0003] Most traditional hydraulic valves are designed for use on land or in shallow sea environments. Their pressure resistance is not enough to cope with the extremely high water pressure in deep sea environments. Ordinary hydraulic valves are prone to valve body deformation, seal failure, valve core sticking and other faults under deep sea pressure and cannot work normally. In addition, although some deep sea hydraulic equipment uses special pressure-resistant casings to enhance pressure adaptability, this design increases the size, weight and cost of the equipment, and brings inconvenience to heat exchange and maintenance. In terms of temperature adaptability, although existing heating devices can control the temperature of hydraulic oil, they consume additional energy and it is difficult to accurately maintain the ideal temperature in a complex deep sea environment.

[0004] Therefore, in order to solve these problems, a new underwater rotary hydraulic proportional valve is proposed to improve the performance and reliability of deep-sea hydraulic systems. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides an underwater rotary hydraulic proportional valve to solve the problems raised in the background technology.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] An underwater rotary hydraulic proportional valve comprises a valve body, a steel sleeve, a shell, a coil, a yoke, a stator core, an inner end cover, a sealing ring a, a dustproof screw, a sealing ring b, a rotary transformer, a permanent magnet, a sealing ring c, a valve sleeve, a valve core, a bearing and a sealing ring d. The valve body is provided with a plurality of hydraulic oil ports, the hydraulic oil ports are connected with the oil ports through a plurality of valve cavities, the shell is installed at one end of the valve body, and a driving cavity is formed inside the shell, the valve core is integrated with a motor shaft and is installed in the valve body, and the valve core can change the connection state between the valve cavities by rotation.

[0008] By adopting the above technical solution and setting the valve core, a close fit between the valve core and the motor is achieved, thereby effectively adjusting the hydraulic connection between the valve chambers. Through the high-precision control of the motor, precise adjustment of the hydraulic flow and pressure can be achieved to meet the needs of complex deep-sea working conditions.

[0009] Preferably, the dustproof screw is tightened under land conditions to prevent dust, and under underwater conditions, the dustproof screw is removed to connect the internal and external pressures, thereby achieving pressure compensation.

[0010] By adopting the above technical solution and setting dustproof screws, the adaptability of the device under different working conditions is ensured, and the reliability of use is improved. In underwater working conditions, the pressure compensation design effectively avoids structural deformation or performance degradation caused by pressure difference.

[0011] Preferably, five annular grooves a, b, c, d and e with equal widths are provided on the outer wall of the valve sleeve, and the annular grooves are used to realize linear adjustment of controlling the output flow rate. The outer wall of the valve core is provided with a plurality of notches a, b, c, d, e, f, g, h, i, j, k and l in sequence along the axial direction, wherein the notches are symmetrically distributed along the radial direction, and the pressure balance on both sides is realized by the circular through holes.

[0012] By adopting the above technical solution and setting the annular groove a, high-precision flow control and smooth operation of the valve core are achieved. By optimizing the geometric structure design, the interference of hydraulic shock on the movement of the valve core is reduced, and the stability of system operation is improved.

[0013] Preferably, the valve core and the valve sleeve cooperate with each other to form a Y-shaped neutral position function. When the valve core is in the neutral position, the oil port P is closed, and the oil ports T, A and B are connected.

[0014] By adopting the above technical solution and setting the valve sleeve, a clear neutral functional state is provided, which improves the stability of the hydraulic system. The neutral function can maintain pressure balance when there is no input signal in the system, reduce energy consumption and extend the service life of the equipment.

[0015] Preferably, when the valve core is in the middle position, the slot i and the slot j are connected through the key slot a, and the slot k and the slot l are connected through the key slot b, so as to ensure that the oil ports T, A, and B remain connected.

[0016] By adopting the above technical solution and setting the keyway b, the reliability and continuity of oil circuit switching when rotating in different directions are achieved, and the hydraulic shock and flow interruption are avoided during the dynamic switching process.

[0017] Preferably, when the valve core rotates clockwise, slot e and slot f are connected through key slot c, slot g and slot h are connected through key slot d, thereby ensuring that oil port BT remains connected before oil port PA is connected, and when the valve core rotates counterclockwise, slot i and slot j are connected through key slot e, slot k and slot l are connected through key slot f, thereby ensuring that oil port AT remains connected before oil port PB is connected.

[0018] By adopting the above technical solution and setting the slot i, efficient operation of the motor and reliable isolation of the hydraulic system are achieved, and the rotor part of the motor is isolated from the hydraulic environment, which ensures high-speed and high-precision operation while reducing equipment maintenance costs.

[0019] Preferably, the concentrated winding limited torque angle motor consists of a housing, a coil, a yoke, a stator core, a permanent magnet, a valve core and a rotary transformer, the coil is wound around the stator core, the valve core, the yoke and the permanent magnet together constitute a rotor, the valve core rotates synchronously with the motor and is lubricated by bearings to reduce friction.

[0020] By adopting the above technical solution and setting bearings, efficient operation of the motor and reliable isolation of the hydraulic system are achieved. The rotor part of the motor is isolated from the hydraulic environment, which ensures high-speed and high-precision operation while reducing equipment maintenance costs.

[0021] Preferably, the rotary transformer is mounted on the inner end cover and is used to feed back the position signal to the controller, wherein the motor adopts a wet structure, wherein low-pressure oil enters the interior of the motor through the oil return port to achieve pressure compensation, thereby adapting to underwater working conditions.

[0022] By adopting the above technical solution and setting up a rotating transformer, the adaptability of the device in complex underwater environments is further improved. The wet structure design not only effectively alleviates the damage of underwater high pressure to the motor structure, but also significantly improves the reliability and service life of the equipment.

[0023] In summary, the present invention mainly has the following beneficial effects:

[0024] 1. The present invention adopts a limited torque angle motor to directly drive the valve core. The valve core and the motor shaft rotate synchronously, and the two have the same angular velocity. This design converts the control of the flow into a control method of the motor angular displacement, and can adjust the flow through precise motor displacement. This control method is not only simpler and more efficient, but also can achieve more stable flow regulation under various working conditions, improves the response speed and control accuracy of the system, and is particularly suitable for flow control needs in complex dynamic environments.

[0025] 2. The present invention adopts a rotating shaft valve core design and opens a circular through hole in the notch of the valve core to balance the pressure on both sides of the valve core, thereby effectively compensating for the radial unbalanced force that may be generated when the rotary valve is working. This innovative design significantly reduces the rotational inertia of the moving parts and improves the performance of the valve core under dynamic loads, so that the entire system can respond to load changes more quickly and stably. This design optimizes the movement performance of the valve core, ensures stability and accuracy at high-speed operation, and greatly improves the system's dynamic load bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the underwater rotary hydraulic proportional valve of the present invention;

[0027] Figure 2 This is a front view of the valve core and valve sleeve of the present invention;

[0028] Figure 3 This is a top view of the valve core and valve sleeve of the present invention;

[0029] Figure 4 yes Figure 2 The cross-sectional view at CC in ;

[0030] Figure 5 It is a structural diagram of the valve core of the present invention;

[0031] Figure 6 It is the schematic diagram of the water / seawater medium system;

[0032] Figure 7 It is a structural schematic diagram of the underwater hydraulic servo valve of the present invention;

[0033] Figure 8 It is a schematic diagram of the valve core structure of the present invention.

[0034] Figure numerals: 1, valve body; 2, steel sleeve; 3, housing; 4, coil; 5, yoke; 6, stator core; 7, inner end cover; 8, sealing ring a; 9, dustproof screw; 10, sealing ring b; 11, rotary transformer; 12, permanent magnet; 13, sealing ring c; 14, valve sleeve; 15, valve core; 16, bearing; 17, sealing ring d; 18, notch a; 19, notch b; 20, notch c; 21, notch d; 22. slot e; 23. slot f; 24. slot g; 25. slot h; 26. slot i; 27. slot j; 28. slot k; 29. ​​slot l; 30. annular groove a; 31. annular groove b; 32. annular groove c; 33. annular groove d; 34. annular groove e; 35. keyway a; 36. keyway b; 37. keyway c; 38. keyway d; 39. keyway e; 40. keyway f. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0036] The following examples are used to illustrate the present invention, but they cannot be used to limit the scope of protection of the present invention. The conditions in the examples can be further adjusted according to specific conditions. Simple improvements to the method of the present invention under the premise of the concept of the present invention belong to the scope of protection claimed in the present invention.

[0037] Example 1

[0038] refer to Figure 1-Figure 5 , an underwater rotary hydraulic proportional valve, comprising a valve body 1, a steel sleeve 2, a shell 3, a coil 4, a yoke 5, a stator core 6, an inner end cover 7, a sealing ring a8, a dustproof screw 9, a sealing ring b10, a rotary transformer 11, a permanent magnet 12, a sealing ring c13, a valve sleeve 14, a valve core 15, a bearing 16 and a sealing ring d17, characterized in that the valve body 1 is provided with a plurality of hydraulic oil ports, the hydraulic oil ports are connected with the oil ports through a plurality of valve cavities, the shell 3 is mounted at one end of the valve body 1, and a driving cavity is formed inside the shell 3, the valve core 15 is integrated with the motor shaft and is mounted in the valve body 1, and the valve core 15 can change the valve cavity by rotation The connection state between the two chambers is ensured by setting the valve core 15, which realizes the close cooperation between the valve core 15 and the motor, thereby effectively adjusting the hydraulic connection between the valve chambers. Through the high-precision control of the motor, the precise adjustment of the hydraulic flow and pressure can be realized to meet the needs of complex deep-sea working conditions. The dustproof screw 9 is tightened under land working conditions for dust prevention, and under underwater working conditions, the dustproof screw 9 is removed to connect the internal and external pressures to achieve pressure compensation. By setting the dustproof screw 9, the adaptability of the device under different working conditions is ensured, and the reliability of use is improved. Under underwater working conditions, the pressure compensation design effectively avoids structural deformation or performance degradation caused by pressure difference.

[0039] refer to Figure 1-Figure 5The outer wall of the valve sleeve 14 is provided with five annular grooves a30, b31, c32, d33 and e34 of equal width, and the annular grooves are used to realize linear adjustment of the output flow rate. The outer wall of the valve core 15 is provided with a plurality of notches a18, b19, c20, d21, e22, f23, g24, h25, i26, j27, k28 and l29 in sequence along the axial direction, wherein the notches are symmetrically distributed along the radial direction, and the pressure balance on both sides is realized by the circular through holes. By setting the annular groove a30, high precision of flow control and smooth operation of the valve core 15 are achieved. By optimizing the geometric structure, the interference of hydraulic shock on the movement of the valve core 15 is reduced, and the stability of the system operation is improved. The valve core 15 and the valve sleeve 14 cooperate with each other to form a Y-type neutral position function. When the valve core 15 is in the neutral position, the oil port P is closed, and the oil ports T, A and B are connected. By setting the valve sleeve 14, a clear neutral position function state is provided, which improves the stability of the hydraulic system. The neutral position function can maintain pressure balance when there is no input signal in the system, reduce energy consumption and extend the service life of the equipment.

[0040] refer to Figure 1-Figure 5 When the valve core 15 is in the middle position, the slot i26 and the slot j27 are connected through the key slot a35, and the slot k28 and the slot l29 are connected through the key slot b36 to ensure that the oil ports T, A, and B are connected. By setting the key slot b36, the reliability and continuity of the oil circuit switching when rotating in different directions are achieved. During the dynamic switching process, the hydraulic shock and flow interruption are avoided. When the valve core 15 rotates clockwise, the slot e22 and the slot f23 are connected through the key slot c37, and the slot g24 and the slot h25 are connected through the key slot d38 is turned on, thereby ensuring that before the oil port PA is turned on, the oil port BT remains turned on, and when the valve core 15 rotates counterclockwise, the slot i26 and the slot j27 are turned on through the key slot e39, and the slot k28 and the slot l29 are turned on through the key slot f40, thereby ensuring that before the oil port PB is turned on, the oil port AT remains turned on. By setting the slot i26, the efficient operation of the motor and the reliable isolation of the hydraulic system are achieved, the rotor part of the motor is isolated from the hydraulic environment, ensuring high-speed and high-precision operation while reducing the equipment maintenance cost.

[0041] refer to Figure 1-Figure 5The concentrated winding limited torque angle motor is composed of a housing 3, a coil 4, a yoke 5, a stator core 6, a permanent magnet 12, a valve core 15 and a rotary transformer 11. The coil 4 is wound on the stator core 6. The valve core 15, the yoke 5 and the permanent magnet 12 together constitute a rotor. The valve core 15 rotates synchronously with the motor and is lubricated by a bearing 16 to reduce friction. By setting the bearing 16, efficient operation of the motor and reliable isolation of the hydraulic system are achieved. The rotor part of the motor is isolated from the hydraulic environment, which ensures high speed and high precision operation while reducing equipment maintenance costs. The rotary transformer 11 is installed on the inner end cover 7 to feed back the position signal to the controller. The motor adopts a wet structure, in which low-pressure oil enters the motor through the oil return port to achieve pressure compensation, thereby adapting to underwater working conditions. By setting the rotary transformer 11, the adaptability of the device in complex underwater environments is further improved. The wet structure design not only effectively alleviates the damage of underwater high pressure to the motor structure, but also significantly improves the reliability and service life of the equipment.

[0042] Example 2

[0043] refer to Figure 6 The present invention also provides an underwater rotary hydraulic proportional valve for use in a deep-sea hydraulic system in a water / seawater medium system, and the specific steps are as follows:

[0044] The hydraulic oil extracted from the oil tank (12) first passes through the filter (10), and the filter (10) filters out foreign particles in the oil to prevent the foreign particles from entering the subsequent hydraulic components and protect other components in the system from wear and blockage. The motor (8) provides power for the entire hydraulic system, and the motor (8) drives the hydraulic pump (9) to work;

[0045] When the oil pressure output by the hydraulic pump (9) reaches or exceeds the pressure value set by the relief valve (3), the relief valve (3) opens, and the excess hydraulic oil flows back to the oil tank (12) through the relief valve (3), thereby ensuring that the system pressure is stable within the set range and preventing the system pressure from being too high and damaging the hydraulic components. The oil flows through the check valve (7), which prevents the oil from flowing back. The oil passes through the speed regulating valve (6), and the flow rate entering the servo valve (5) can be adjusted by changing the opening of the speed regulating valve (6).

[0046] The servo valve (5) can accurately control the flow direction and flow rate of the oil, thereby realizing precise control of the actuator (1). The oil passes through the hydraulically controlled one-way valve (4), and the pressure gauge is used to monitor the pressure of the system in real time;

[0047] If the actuator is a hydraulic cylinder (1), when high-pressure oil enters one chamber of the hydraulic cylinder, it pushes the piston to move, achieving linear motion. By controlling the flow rate and pressure of the oil entering the two chambers of the hydraulic cylinder, the movement speed and direction of the piston can be controlled. If the actuator is a hydraulic motor (1), after the high-pressure oil enters the hydraulic motor, it pushes the rotor of the motor to rotate, achieving rotary motion. Similarly, by controlling the flow rate and pressure of the oil, the speed and direction of the hydraulic motor can be controlled.

[0048] Example 3

[0049] The present invention also provides an underwater hydraulic servo valve, referring to Figure 7 The servo valve structure diagram in the modification case includes a valve core (41), a valve sleeve (42), a valve body (43), a motor shaft (44), a yoke (45), a permanent magnet (46), a stator core (47), a connector (48), a rotary transformer (49), an inner end cover (50), a steel sleeve (51), a coil (52), a housing (53), and a spring return mechanism (54), wherein the valve body (43) is provided with a plurality of hydraulic oil ports, the hydraulic oil ports are connected to the oil ports through a plurality of valve cavities, the housing (53) is installed at one end of the valve body (43), the valve core (41) is connected to the motor shaft and installed in the valve body (43), and the valve core (41) can change the connection state between the valve cavities by rotation;

[0050] refer to Figure 8 , is a schematic diagram of the valve core structure in the modification case. The valve core has two pairs of upper and lower notches 55(a)55(b), 56(a)56(b), which are symmetrically distributed along the radial direction, and a circular through hole is opened in each pair of notches to balance the pressure on both sides. The valve core has pressure equalizing grooves at both ends, combined with a symmetrical geometric structure, so that the valve core is evenly stressed in the radial direction, and the radial unbalanced force of the rotary valve is effectively compensated.

[0051] Working principle: Please refer to Figure 1-Figure 5 As shown, the underwater rotary hydraulic proportional valve of the present invention is based on a limited torque angle motor driving the valve core 15 for precise control. The motor shaft and the valve core 15 rotate synchronously, and the two have the same angular velocity. By rotating the valve core 15, the connection state between the valve chambers is changed, thereby controlling the flow of the hydraulic oil. The valve core 15 cooperates with the valve sleeve 14 to form a Y-type neutral position function. When the valve core 15 is in the neutral position, the oil port P is closed, and the oil ports T, A and B are connected to ensure stable operation of the system.

[0052] Under underwater working conditions, the dustproof screw 9 is removed to realize the connection between the internal and external pressures, thereby achieving the pressure compensation function, thereby adapting to the underwater high-pressure environment. The design of multiple annular grooves and notches is used to achieve precise flow regulation and pressure balance, while reducing the radial unbalanced force of the valve core 15 during operation, significantly improving the stability and dynamic response capability of the valve core 15;

[0053] In addition, the rotary transformer 11 works in conjunction with the motor to feed back the rotation signal of the valve core 15 to the controller, ensuring the stability and reliability of the valve in an underwater environment. The overall design enables the underwater rotary hydraulic proportional valve to have strong anti-pollution capabilities, no axial leakage problems, and can operate stably and reliably under deep-sea high-pressure and low-temperature conditions.

[0054] Although the embodiments of the present invention have been shown and described, it is understandable to those skilled in the art that, unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "including" or "comprising" and the like used in the present invention mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words "connect" or "connected" and the like are not limited to physical or mechanical connections, but may also include electrical connections, whether direct or indirect. "Up", "down", "left", "right", etc. are only used to indicate relative position relationships. When the absolute position of the described object changes, the relative position relationship may also change accordingly.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0056] In the final constructed system or device, the servo valves, proportional valves and reversing valves operating based on this specific principle should all be included in the comprehensive protection mechanism design.

Claims

1. An underwater rotary hydraulic proportional valve, comprising a valve body (1), a steel sleeve (2), a housing (3), a coil (4), a yoke (5), a stator core (6), an inner end cover (7), a sealing ring a (8), a dustproof screw (9), a sealing ring b (10), a rotary transformer (11), a permanent magnet (12), a sealing ring c (13), a valve sleeve (14), a valve core (15), a bearing (16) and a sealing ring d (17), characterized in that: The valve body (1) is provided with a plurality of hydraulic oil ports, the hydraulic oil ports being connected to the oil ports through a plurality of valve chambers. The housing (3) is mounted on one end of the valve body (1), and a drive chamber is formed inside the housing (3). The valve core (15) is integrated with the motor shaft and is mounted inside the valve body (1). The valve core (15) can change the connection state between the valve chambers by rotating.

2. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: The dustproof screw (9) is tightened under land conditions to prevent dust, while under underwater conditions, the dustproof screw (9) is removed to connect the internal and external pressures, thereby achieving pressure compensation.

3. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: The outer wall of the valve sleeve (14) is provided with five annular grooves a (30), annular groove b (31), annular groove c (32), annular groove d (33), and annular groove e (34) of equal width, wherein the annular grooves are used to realize linear regulation of output flow control, and the outer wall of the valve core (15) is provided with a plurality of notches a (18), notches b (19), notches c (20), notches d (21), notches e (22), notches f (23), notches g (24), notches h (25), notches i (26), notches j (27), notches k (28), and notches l (29) in sequence along the axial direction, wherein the notches are symmetrically distributed along the radial direction, and pressure balance on both sides is realized by the circular through holes.

4. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: The valve core (15) and the valve sleeve (14) cooperate with each other to form a Y-shaped neutral position function. When the valve core (15) is in the neutral position, the oil port P is closed, and the oil ports T, A and B are connected.

5. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: When the valve core (15) is in the middle position, the slot i (26) and the slot j (27) are connected through the key slot a (35), and the slot k (28) and the slot l (29) are connected through the key slot b (36), so as to ensure that the oil ports T, A, and B are connected.

6. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: When the valve core (15) rotates clockwise, the slot e (22) and the slot f (23) are connected via the key slot c (37), and the slot g (24) and the slot h (25) are connected via the key slot d (38), thereby ensuring that the oil port BT remains connected before the oil port PA is connected, and when the valve core (15) rotates counterclockwise, the slot i (26) and the slot j (27) are connected via the key slot e (39), and the slot k (28) and the slot l (29) are connected via the key slot f (40), thereby ensuring that the oil port AT remains connected before the oil port PB is connected.

7. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: The concentrated winding limited torque angle motor is composed of a housing (3), a coil (4), a yoke (5), a stator core (6), a permanent magnet (12), a valve core (15) and a rotary transformer (11). The coil (4) is wound on the stator core (6). The valve core (15), the yoke (5) and the permanent magnet (12) together constitute a rotor. The valve core (15) rotates synchronously with the motor and is lubricated by a bearing (16) to reduce friction.

8. The underwater rotary hydraulic proportional valve according to claim 1, characterized in that: The rotary transformer (11) is mounted on the inner end cover (7) and is used to feed back the position signal to the controller, wherein the motor adopts a wet structure, wherein low-pressure oil enters the motor through the oil return port to achieve pressure compensation, thereby adapting to underwater working conditions. Based on this working principle, the modified and extended rotary hydraulic servo valve and rotary hydraulic reversing valve are also within the scope of the rights.

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