Actuating cylinder with output pressure in direct proportion to stroke

Abstract

The invention relates to the technical field of airplane wheel braking, in particular to an actuator cylinder with output pressure in direct proportion to stroke, which comprises a push rod, a nut, a piston, a cylinder body, an oil cup, a sealing ring, a shell, a pressure regulating spring, a small piston, a buffer spring, a spring seat and an exhaust nozzle assembly, the piston is installed in the cylinder, the sealing ring is installed in an installation groove in the lower middle of the outer circle of the piston, the cylinder is connected with the shell in a threaded mode, the cylinder is sleeved with the oil cup, the upper end of the small piston is inserted into an axial hole in the lower end of the piston, and the outer circle face of the small piston is sleeved with the pressure adjusting spring. The spring seat is installed at the bottom of a cavity of the shell, the buffer spring is arranged on the spring seat in a sleeved mode, the moving distance of the small piston is in direct proportion to displacement of the piston and is in inverse proportion to rigidity of the pressure adjusting spring, input pressure is in direct proportion to stroke of the piston in the braking process, and control force is moderate.

Description

Technical Field

[0001] The invention relates to the technical field of wheel brakes, and in particular to an actuator cylinder whose output pressure is proportional to the stroke. Background Art

[0002] As an important brake component, the actuator is used in the helicopter wheel brake system. It is installed under the helicopter pedal and converts the force applied by the pilot to the brake pedal into hydraulic pressure output. The output pressure is transmitted to the brake distribution valve through the system pipeline to control the brake distribution valve to output the brake pressure, so as to achieve ground taxiing, turning and braking of the helicopter. On a general helicopter, it is equipped with a brake distribution valve, four actuators, and four brake pedals, one for the left and right feet of the pilot and co-pilot respectively. The brake distribution valve has four control pressure input ports, which are connected to the output ports of the four actuators through pipelines. The oil output by the actuators enters the four brake control chambers of the brake distribution valve respectively. The brake distribution valve has a system pressure input port and two brake pressure output ports. The two brake pressure output ports of the brake distribution valve are connected to the left and right wheel brake devices respectively. When the helicopter needs to taxi and turn on the ground, the main pilot or co-pilot presses on the left and right brake pedals with different forces, the left and right actuators output different pressures, and the two brake pressure output ports of the brake distribution valve output different brake pressures, so that the left and right wheel speeds are different to achieve turning; when braking is needed, the main pilot or co-pilot presses on the left and right brake pedals with both feet at the same time, and the two brake pressure output ports of the brake distribution valve output the same maximum brake pressure to stop the helicopter.

[0003] When braking the wheel, the pilot steps on the pedal, requiring the actuator to output 6MPa pressure. Pilots reported that the brakes were too hard, the pedal stroke was small, and the foot had not yet extended to the optimal force state, but the actuator had already output very high pressure, making it impossible to step on the pedal, and requiring a lot of control force. Similar products all have this problem. Controlling the output pressure of the actuator under the specified stroke is a technical problem that needs to be solved at present. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides an actuator whose output pressure is proportional to the stroke, so as to solve the problems of too hard brakes and large operating force.

[0005] The present invention discloses the following technical scheme: an actuator cylinder whose output pressure is proportional to the stroke, comprising a push rod, a nut, a piston, a cylinder, an oil cup, a sealing ring, a shell, a pressure regulating spring, a small piston, a buffer spring, a spring seat and an exhaust nozzle assembly, wherein the push rod is connected to the piston through a threaded connection and is locked by a nut, the radial threaded hole of the push rod is connected to the axial exhaust hole of the piston, the exhaust nozzle assembly is installed in the radial threaded hole of the push rod, the piston is installed in the cylinder, and a sealing ring is installed in a mounting groove at the lower middle part of the outer circle of the piston through a shaft shoulder limiter at the upper part of the piston, and the sealing ring is located between the piston and the cylinder The cylinder is connected to the shell by a threaded connection, the oil cup is sleeved outside the cylinder, the upper and lower end faces of the oil cup are respectively abutted against the boss end face of the cylinder and the end face of the shell, the interior of the small piston is a cavity with an open upper end and a sealed bottom, the upper end of the small piston is inserted into the axial hole at the lower end of the piston, the pressure-adjusting spring is sleeved on the outer cylindrical surface of the small piston, the upper and lower ends of the pressure-adjusting spring are respectively abutted against the lower end face of the piston and the boss end face at the bottom of the small piston, the spring seat is installed at the bottom of the cavity of the shell, the buffer spring is sleeved on the spring seat, the upper and lower ends of the buffer spring are respectively abutted against the boss end face at the bottom of the small piston and the boss end face at the bottom of the spring seat.

[0006] Furthermore, a nozzle assembly is installed in the radial mounting hole at the bottom of the housing; Furthermore, sealing members are provided on both upper and lower sides between the cylinder and the oil cup; Further, the push rod is hinged to the brake pedal; Furthermore, a spherical bearing is installed at the bottom of the housing; Furthermore, the piston is provided with radial exhaust holes near the shaft shoulder, the radial exhaust holes are connected to the inner cavity of the cylinder, oil holes are distributed circumferentially in the middle of the piston, and a radial hole is provided in the middle of the cylinder to communicate with the inner cavity of the oil cup.

[0007] Beneficial effects: Compared with the prior art, the output pressure of the actuator cylinder of the present invention is proportional to the stroke, and the pressure-regulating spring is arranged between the piston and the small piston, in cooperation with the cylinder, oil cup, shell, buffer spring and exhaust nozzle assembly. When the operating force of the brake pedal is transmitted to the piston, the moving distance of the small piston is proportional to the displacement of the piston and inversely proportional to the stiffness of the pressure-regulating spring. When the pedal is pressed to the optimal force state, the displacement of the piston reaches the maximum stroke, and the output pressure of the high-pressure chamber reaches the maximum braking pressure. During the braking process, the input pressure is proportional to the piston stroke, and the operating force is moderate. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the structure of the actuator of the present invention in which the output pressure is proportional to the stroke; Figure 2 It is a schematic diagram of the piston structure of the actuator cylinder in which the output pressure is proportional to the stroke of the present invention; Figure 3It is a schematic diagram of the cylinder structure of the actuator cylinder of the present invention in which the output pressure is proportional to the stroke; Figure 4 It is a schematic diagram of the push rod structure of the actuator cylinder in which the output pressure is proportional to the stroke of the present invention; Figure 5 It is a schematic diagram of the shell structure of the actuator of the present invention in which the output pressure is proportional to the stroke; In the figure: 1-push rod, 2-nut, 3-piston, 4-cylinder, 5-oil cup, 6-sealing ring, 7-housing, 8-pressure regulating spring, 9-small piston, 10-buffer spring, 11-spring seat, 12-spherical bearing, 13-take-in nozzle assembly, 14-exhaust nozzle assembly; 101- radial threaded hole, 301- axial exhaust hole, 302- shoulder, 303- mounting groove, 304- axial hole, 305- oil hole, 306- radial exhaust hole, 401- radial hole, 701- radial mounting hole. DETAILED DESCRIPTION

[0009] like Figures 1 to 5 As shown, an actuator cylinder whose output pressure is proportional to the stroke comprises a push rod 1, a nut 2, a piston 3, a cylinder body 4, an oil cup 5, a sealing ring 6, a housing 7, a pressure regulating spring 8, a small piston 9, a buffer spring 10, a spring seat 11 and an exhaust nozzle assembly 14. The push rod 1 is connected to the piston 3 by threads and is locked by a nut 2. The radial threaded hole 101 of the push rod 1 is connected to the axial exhaust hole 301 of the piston 3. The exhaust nozzle assembly 14 is installed in the radial threaded hole 101 of the push rod 1. The piston 3 is installed in the cylinder body 4. The piston 3 is limited by the shaft shoulder 302 on the upper part of the piston 3. The piston 3 can move axially in the cylinder body 4. A sealing ring 6 is installed in the mounting groove 303 at the lower middle part of the outer circle of the piston 3. The sealing ring 6 is located between the piston 3 and the cylinder body 4. The cylinder body 4 is connected to the housing 7 by threads. The oil cup 5 is sleeved on the outside of the cylinder 4, and the upper and lower end faces of the oil cup 5 are respectively abutted against the boss end face of the cylinder 4 and the end face of the shell 7. The interior of the small piston 9 is a cavity with an open upper end and a sealed bottom. The upper end of the small piston 9 is inserted into the axial hole 304 at the lower end of the piston 3, and the small piston 9 can move linearly in the axial hole 304. A seal is provided between the small piston 9 and the piston 3. The pressure-regulating spring 8 is sleeved on the outer cylindrical surface of the small piston 9, and the upper and lower ends of the pressure-regulating spring 8 are respectively abutted against the lower end face of the piston 3 and the boss end face at the bottom of the small piston 9. The spring seat 11 is installed at the bottom of the cavity of the shell 7. The buffer spring 10 is sleeved on the spring seat 11, and the upper and lower ends of the buffer spring 10 are respectively abutted against the boss end face at the bottom of the small piston 9 and the boss end face at the bottom of the spring seat 11. The buffer spring 10 provides support force for the small piston 9.

[0010] A nozzle assembly 13 is installed in the radial mounting hole 701 at the bottom of the housing 7, and is used to connect the brake system pipeline, so that the oil flows into and out of the actuator cylinder, and transmits the hydraulic pressure to the brake distribution valve; Seals are provided on both the upper and lower sides between the cylinder 4 and the oil cup 5 to prevent oil leakage; The push rod 1 is hinged to the brake pedal, and the push rod 1 receives the force of the pedal and transmits it to the piston 3; The bottom of the housing 7 is provided with a spherical bearing 12, and the actuator is mounted on the machine body using the spherical bearing 12. The piston 3 is provided with a radial exhaust hole 306 near the shaft shoulder 302, and the radial exhaust hole 306 is connected to the inner cavity of the cylinder 4. The middle part of the piston 3 is circumferentially distributed with oil holes 305, and the middle part of the cylinder 4 is provided with a radial hole 401 connected to the inner cavity of the oil cup 5, so that the piston 3 and the cylinder 4 part located below the sealing ring 6 and the position between the inner cavity of the shell 7 and the small piston 9 constitute a high-pressure chamber, and the piston 3 and the cylinder 4 part located above the sealing ring 6 and the inner cavity of the oil cup 5 and the inner cavity of the small piston 9 constitute an oil storage chamber.

[0011] When braking is needed, the pilot steps on the pedal, and the push rod 1 pushes the piston 3 to move downward as a whole for a certain distance, and the high-pressure chamber begins to build up pressure. At the same time, the pressure acts on the lower end surface of the small piston 9. Under the action of pressure, the small piston 9 moves upward, the pressure regulating spring 8 is compressed, and the buffer spring 10 is extended. The moving distance of the small piston 9 is proportional to the displacement of the piston 3 and inversely proportional to the stiffness of the pressure regulating spring 8. When the small piston 9 moves upward, the oil inside the piston 3 flows back to the oil storage chamber through the oil hole 305 in the middle thereof. Continue to step on the pedal. As the displacement of the piston 3 increases, the compression amount of the pressure regulating spring 8 increases, the elastic force increases, and the output pressure of the high-pressure chamber also increases. When the pedal is stepped on to the optimal force application state, the displacement of the piston 3 reaches the maximum stroke, and the output pressure of the high-pressure chamber reaches the highest braking pressure. During the overall downward movement of the piston 3, the volume of the oil storage chamber increases, and the exhaust nozzle assembly 14 installed through the axial exhaust hole 301, the radial exhaust hole 306 of the piston 3 and the radial threaded hole 101 of the push rod 1 inhales air to balance the air pressure, thereby avoiding the formation of vacuum in the oil storage chamber to generate negative pressure. During braking, the output

[11] pressure is proportional to the stroke of piston 3, and the operating force is moderate.

[0012] When the brakes need to be released, the pilot releases the pedal, the pressure-adjusting spring 8 releases its elastic force to push the piston 3 upward and the small piston 9 downward, the piston 3 moves up to the limit position, the high-pressure chamber of the actuator and the oil storage chamber are connected through the radial hole 401 of the cylinder 4, and the pressure in the high-pressure chamber drops to zero; during the overall upward movement of the piston 3, the volume of the oil storage chamber decreases, and the pressure is balanced by connecting the piston 3 to the atmosphere through the axial exhaust hole 301, the radial exhaust hole 306 and the exhaust nozzle assembly 14, thereby avoiding pressure in the oil storage chamber.

[0013] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An actuator cylinder whose output pressure is proportional to the stroke, comprising a push rod (1), a nut (2), a piston (3), a cylinder (4), an oil cup (5), a sealing ring (6), a housing (7), a pressure regulating spring (8), a small piston (9), a buffer spring (10), a spring seat (11) and an exhaust nozzle assembly (14), characterized in that: The push rod (1) and the piston (3) are connected by threads and locked by a nut (2). The radial threaded hole (101) of the push rod (1) is connected to the axial exhaust hole (301) of the piston (3). The exhaust nozzle assembly (14) is installed in the radial threaded hole (101) of the push rod (1). The piston (3) is installed in the cylinder (4) and is limited by the shaft shoulder (302) on the upper part of the piston (3). A sealing ring (6) is installed in the installation groove (303) at the lower middle part of the outer circle of the piston (3). The sealing ring (6) is located between the piston (3) and the cylinder (4). The cylinder (4) is connected to the housing (7) by threads. The oil cup (5) is sleeved on the outside of the cylinder (4). The oil cup (5) The upper and lower end surfaces are respectively in contact with the boss end surface of the cylinder (4) and the end surface of the shell (7); the interior of the small piston (9) is a cavity with an open upper end and a sealed bottom; the upper end of the small piston (9) is inserted into the axial hole (304) at the lower end of the piston (3); the pressure regulating spring (8) is sleeved on the outer cylindrical surface of the small piston (9); the upper and lower ends of the pressure regulating spring (8) are respectively in contact with the lower end surface of the piston (3) and the boss end surface at the bottom of the small piston (9); the spring seat (11) is installed at the bottom of the cavity of the shell (7); the buffer spring (10) is sleeved on the spring seat (11); the upper and lower ends of the buffer spring (10) are respectively in contact with the boss end surface at the bottom of the small piston (9) and the boss end surface at the bottom of the spring seat (11).

2. The actuator with output pressure proportional to stroke according to claim 1, characterized in that: A nozzle assembly (13) is installed in the radial mounting hole (701) at the bottom of the housing (7).

3. The actuator with output pressure proportional to stroke according to claim 1, characterized in that: Seals are provided on both upper and lower sides between the cylinder (4) and the oil cup (5).

4. The actuator with output pressure proportional to stroke according to claim 1, characterized in that: The push rod (1) is hinged to the brake pedal.

5. The actuator with output pressure proportional to stroke according to claim 1, characterized in that: A spherical bearing (12) is installed at the bottom of the housing (7).

6. The actuator with output pressure proportional to stroke according to claim 1, characterized in that: The piston (3) is provided with a radial exhaust hole (306) near the shaft shoulder (302), the middle part of the piston (3) is provided with oil holes (305) distributed around the circumference, and the middle part of the cylinder (4) is provided with a radial hole (401).

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